WorldWideScience

Sample records for plastic material behavior

  1. Mechanical behavior of plastic materials for automobile cockpit module

    Science.gov (United States)

    Woo, Changsu.; Park, Hyunsung.; Jo, Jinho.

    2013-12-01

    Engineering plastics are used in instrument panels, interior trims, and other vehicle applications, and the thermo-mechanical behaviors of plastic materials are strongly influenced by many environmental factors such as temperature, sunlight, and rain. As the material properties change, the mechanical parts create unexpected noise. In this study, the dynamic mechanical property changes of plastics used in automobiles are measured to investigate the effect of temperature. Visco-elastic properties such as the glass transition temperature and storage modulus and loss factors under temperature and frequency sweeps were measured. The data results were compared with the original ones before aging to analyze the behavioral changes. It was found that as the temperature increased, the storage modulus decreased and the loss factor increased slightly.

  2. Material characterization and finite element modelling of cyclic plasticity behavior for 304 stainless steel using a crystal plasticity model

    OpenAIRE

    Lu, Jiawa; Sun, Wei; Becker, Adib A.

    2016-01-01

    Low cycle fatigue tests were carried out for a 304 stainless steel at room temperature. A series of experimental characterisations, including SEM, TEM, and XRD were conducted for the 304 stainless steel to facilitate the understanding of the mechanical responses and microstructural behaviour of the material under cyclic loading including nanostructure, crystal structure and the fractured surface. The crystal plasticity finite element method (CPFEM) is a powerful tool for studying the microstr...

  3. Deformation mechanisms of plasticized starch materials.

    Science.gov (United States)

    Mikus, P-Y; Alix, S; Soulestin, J; Lacrampe, M F; Krawczak, P; Coqueret, X; Dole, P

    2014-12-19

    The aim of this paper is to understand the influence of plasticizer and plasticizer amount on the mechanical and deformation behaviors of plasticized starch. Glycerol, sorbitol and mannitol have been used as plasticizers. After extrusion of the various samples, dynamic mechanical analyses and video-controlled tensile tests have been performed. It was found that the nature of plasticizer, its amount as well as the aging of the material has an impact on the involved deformation mechanism. The variations of volume deformation could be explained by an antiplasticization effect (low plasticizer amount), a phase-separation phenomenon (excess of plasticizer) and/or by the retrogradation of starch.

  4. Two phase modeling of the influence of plastic strain on the magnetic and magnetostrictive behaviors of ferromagnetic materials

    Science.gov (United States)

    Hubert, Olivier; Lazreg, Said

    2017-02-01

    A growing interest of automotive industry in the use of high performance steels is observed. These materials are obtained thanks to complex manufacturing processes whose parameters fluctuations lead to strong variations of microstructure and mechanical properties. The on-line magnetic non-destructive monitoring is a relevant response to this problem but it requires fast models sensitive to different parameters of the forming process. The plastic deformation is one of these important parameters. Indeed, ferromagnetic materials are known to be sensitive to stress application and especially to plastic strains. In this paper, a macroscopic approach using the kinematic hardening is proposed to model this behavior, considering a plastic strained material as a two phase system. Relationship between kinematic hardening and residual stress is defined in this framework. Since stress fields are multiaxial, an uniaxial equivalent stress is calculated and introduced inside the so-called magneto-mechanical multidomain modeling to represent the effect of plastic strain. The modeling approach is complemented by many experiments involving magnetic and magnetostrictive measurements. They are carried out with or without applied stress, using a dual-phase steel deformed at different levels. The main interest of this material is that the mechanically hard phase, soft phase and the kinematic hardening can be clearly identified thanks to simple experiments. It is shown how this model can be extended to single phase materials.

  5. Shielding behaviors of some polymer and plastic materials for gamma-rays

    Science.gov (United States)

    Mann, Kulwinder Singh; Rani, Asha; Heer, Manmohan Singh

    2015-01-01

    Gamma-rays interaction parameters with six polymer and plastic materials have been computed and investigated for their shielding behaviours in the experimental energy range 10-1400 keV. Low mass-density and ability to transform into thin-sheets of H-containing plastic and polymer materials generate the curiosity for present study. Gamma Ray Interaction Coefficients (GRIC)-toolkit: a computer program designed in MS-Excel, 2007 for the investigation. The toolkit has the capability to compute different parameters linked to shielding properties of the sample-material such that; mass attenuation coefficients (μ/ρ), mass energy absorption coefficients (μen/ρ), equivalent atomic number (Zeq), KERMA (kinetic energy released per unit mass). Polyvinyl Chloride (PVC) seems to be the best shield for gamma radiations in energy range 10-110 keV. The interaction parameters for selected samples have been computed and provided in the extended energy range 0.015-15 MeV.

  6. Finite deformation analysis of continuum structures with time dependent anisotropic elastic plastic material behavior (LWBR/AWBA Development Program)

    Energy Technology Data Exchange (ETDEWEB)

    Hutula, D.N.

    1980-03-01

    A finite element procedure is presented for finite deformation analysis of continuum structures with time-dependent anisotropic elastic-plastic material behavior. An updated Lagrangian formulation is used to describe the kinematics of deformation. Anisotropic constitutive relations are referred, at each material point, to a set of three mutually orthogonal axes which rotate as a unit with an angular velocity equal to the spin at the point. The time-history of the solution is generated by using a linear incremental procedure with residual force correction, along with an automatic time step control algorithm which chooses time step sizes to control the accuracy and numerical stability of the solution.

  7. Laser cutting plastic materials

    Energy Technology Data Exchange (ETDEWEB)

    Van Cleave, R.A.

    1980-08-01

    A 1000-watt CO/sub 2/ laser has been demonstrated as a reliable production machine tool for cutting of plastics, high strength reinforced composites, and other nonmetals. More than 40 different plastics have been laser cut, and the results are tabulated. Applications for laser cutting described include fiberglass-reinforced laminates, Kevlar/epoxy composites, fiberglass-reinforced phenolics, nylon/epoxy laminates, ceramics, and disposable tooling made from acrylic.

  8. Computational materials science: Nanoscale plasticity

    DEFF Research Database (Denmark)

    Jacobsen, Karsten Wedel; Schiøtz, Jakob

    2002-01-01

    How does plastic deformation of polycrystalline materials with grain sizes less than 100 nm look at the atomic scale? A large-scale molecular dynamics simulation of nanocrystalline alluminium reveals some surprising behaviour.......How does plastic deformation of polycrystalline materials with grain sizes less than 100 nm look at the atomic scale? A large-scale molecular dynamics simulation of nanocrystalline alluminium reveals some surprising behaviour....

  9. Lecture notes on Elasto-plastic materials

    DEFF Research Database (Denmark)

    Hededal, Ole

    2007-01-01

    Brief introduction to material modelling within the framework of rate independent elasto-plastic constitutive modelling......Brief introduction to material modelling within the framework of rate independent elasto-plastic constitutive modelling...

  10. Plastic Recycling Experiments in Materials Education

    Science.gov (United States)

    Liu, Ping; Waskom, Tommy L.

    1996-01-01

    The objective of this project was to introduce a series of plastic recycling experiments to students in materials-related courses such as materials science, material technology and materials testing. With the plastic recycling experiments, students not only can learn the fundamentals of plastic processing and properties as in conventional materials courses, but also can be exposed to the issue of materials life cycle and the impact on society and environment.

  11. Plasticity in Ultra Fine Grained Materials

    Energy Technology Data Exchange (ETDEWEB)

    Koslowski, Marisol [Purdue Univ., West Lafayette, IN (United States)

    2015-04-15

    Understanding the mechanisms of deformation of nanocrystalline (nc) materials is critical to the design of micro and nano devices and to develop materials with superior fracture strength and wear resistance for applications in new energy technologies. In this project we focused on understanding the following plastic deformation processes described in detail in the following sections: 1. Plastic strain recovery (Section 1). 2. Effect of microstructural variability on the yield stress of nc metals (Section 2). 3. The role of partial and extended full dislocations in plastic deformation of nc metals (Section 3).

  12. Plasticity of pressure-sensitive materials

    CERN Document Server

    Ochsner, Andreas

    2014-01-01

    Classical plasticity theory of metals is independent of the hydrostatic pressure. However, if the metal contains voids or pores or if the structure is composed of cells, this classical assumption is no more valid and the influence of the hydrostatic pressure must be incorporated in the constitutive description. Looking at the microlevel, metal plasticity is connected with the uniform planes of atoms organized with long-range order. Planes may slip past each other along their close-packed directions. The result is a permanent change of shape within the crystal and plastic deformation. The presence of dislocations increases the likelihood of planes slipping. Nowadays, the theory of pressure sensitive plasticity is successfully applied to many other important classes of materials (polymers, concrete, bones etc.) even if the phenomena on the micro-level are different to classical plasticity of metals. The theoretical background of this phenomenological approach based on observations on the macro-level is describe...

  13. The molecular interfacial structure and plasticizer migration behavior of "green" plasticized poly(vinyl chloride).

    Science.gov (United States)

    Zhang, Xiaoxian; Li, Yaoxin; Hankett, Jeanne M; Chen, Zhan

    2015-02-14

    Tributyl acetyl citrate (TBAC), a widely-used "green" plasticizer, has been extensively applied in products for daily use. In this paper, a variety of analytical tools including sum frequency generation vibrational spectroscopy (SFG), coherent anti-Stokes Raman spectroscopy (CARS), contact angle goniometry (CA), and Fourier transform infrared spectroscopy (FTIR) were applied together to investigate the molecular structures of TBAC plasticized poly(vinyl chloride) (PVC) and the migration behavior of TBAC from PVC-TBAC mixtures into water. We comprehensively examine the effects of oxygen and argon plasma treatments on the surface structures of PVC-TBAC thin films containing various bulk percentages of plasticizers and the leaching behavior of TBAC into water. It was found that TBAC is a relatively stable PVC plasticizer compared to traditional non-covalent plasticizers but is also surface active. Oxygen plasma treatment increased the hydrophilicity of TBAC-PVC surfaces, but did not enhance TBAC leaching. However, argon plasma treatment greatly enhanced the leaching of TBAC molecules from PVC plastics to water. Based on our observations, we believe that oxygen plasma treatment could be applied to TBAC plasticized PVC products to enhance surface hydrophilicity for improving the biocompatibility and antibacterial properties of PVC products. The structural information obtained in this study will ultimately facilitate a molecular level understanding of plasticized polymers, aiding in the design of PVC materials with improved properties.

  14. Aktau Plastics Plant Explosives Material Report

    Energy Technology Data Exchange (ETDEWEB)

    CASE JR.,ROGER S.

    1999-12-01

    The U.S. Department of Energy (DOE) has been cooperating with the Republic of Kazakhstanin Combined Threat Reduction (CTR) activities at the BN350 reactor located at the Mangyshlak Atomic Energy Complex (MAEC) in the city of Aktau, Kazakhstan since 1994. DOE contract personnel have been stationed at this facility for the last two years and DOE representatives regularly visit this location to oversee the continuing cooperative activities. Continued future cooperation is planned. A Russian news report in September 1999 indicated that 75 metric tons of organic peroxides stored at the Plastics Plant near Aktau were in danger of exploding and killing or injuring nearby residents. To ensure the health and safety of the personnel at the BN350 site, the DOE conducted a study to investigate the potential danger to the BN350 site posed by these materials at the Plastics Plant. The study conclusion was that while the organic peroxides do have hazards associated with them, the BN350 site is a safe distance from the Plastics Plant. Further, because the Plastics Plant and MAEC have cooperative fire-fighting agreements,and the Plastics Plant had exhausted its reserve of fire-fighting foam, there was the possibility of the Plastics Plant depleting the store of fire-fighting foam at the BN350 site. Subsequently, the DOE decided to purchase fire-fighting foam for the Plastics Plant to ensure the availability of free-fighting foam at the BN350 site.

  15. Plastic materials currently used in Mongolia

    Institute of Scientific and Technical Information of China (English)

    Ruvjir Shagdarsuren; Nachin Baasanjav; Sosor Baatarjav

    2007-01-01

    The first skin-flap procedures were performed in Mongolia by a team of Chinese doctors ( Chenod, Chen)who treated children with burn injuries in the 1950s. The field of plastic surgery was further developed through assistance from the former Soviet Union and is now widely practiced by a number of surgeons around the country.In recent years, the fast evolving field of plastic surgery in Mongolia has created a need for clear and consistent system for the classification of various plastic materials. A team of Mongolian surgeons at the National Hospital for Traumatology, Orthopedics, Rehabilitation and Teaching Research have completed a research programme aimed at adopting a leading classification system that can facilitate effective communication between plastic surgeons. This requires the chosen system to be in line with modern trends in plastic surgery and the established international norms.As a result of extensive research and analysis, they have developed a customized version of Vasiliev's classification that focuses on formulating general principles of the description of plastic materials based on their functional characteristics. The main reason for this selection is its similarity with existing Mongolian standards as well as its principles that contain important implications for surgery.

  16. Micromechanical study of plasticity of granular materials

    NARCIS (Netherlands)

    Kruyt, N.P.

    2010-01-01

    Plastic deformation of granular materials is investigated from the micromechanical viewpoint, in which the assembly of particles and interparticle contacts is considered as a mechanical structure. This is done in three ways. Firstly, by investigating the degree of redundancy of the system by compari

  17. Mechanical behavior of emerging materials

    Directory of Open Access Journals (Sweden)

    Challapalli Suryanarayana

    2012-11-01

    Full Text Available Nanocrystalline and glassy materials, especially the bulk metallic glasses are of relatively recent origin and exhibit high strength, but lack sufficient plasticity. A clear understanding of the mechanical behavior of these novel materials is essential before these can be seriously considered for structural applications. A great deal of research has been conducted over the past couple of decades and a vast amount of data has been generated. Here, results on strength, ductility, and deformation behavior of these novel materials have been reviewed. Recent results have been highlighted and problems, wherever they exist, have been pointed out. New directions for enhancing the understanding of the mechanical behavior of these interesting materials have been suggested.

  18. Waste Plastic Converting into Hydrocarbon Fuel Materials

    Energy Technology Data Exchange (ETDEWEB)

    Sarker, Moinuddin; Mamunor Rashid, Mohammad; Molla, Mohammad

    2010-09-15

    The increased demand and high prices for energy sources are driving efforts to convert organic compounds into useful hydrocarbon fuels. Although much of this work has focused on biomass, there are strong benefits to deriving fuels from waste plastic material. Natural State Research Inc. (NSR) has invented a simple and economically viable process to decompose the hydrocarbon polymers of waste plastic into the shorter chain hydrocarbon of liquid fuel (patent pending). The method and principle of the production / process will be discussed. Initial tests with several widely used polymers indicate a high potential for commercialization.

  19. External insulation with cellular plastic materials

    DEFF Research Database (Denmark)

    Sørensen, Lars Schiøtt; Nielsen, Anker

    2014-01-01

    External thermal insulation composite systems (ETICS) can be used as extra insulation of existing buildings. The system can be made of cellular plastic materials or mineral wool. There is a European Technical guideline, ETAG 004, that describe the tests that shall be conducted on such systems....... This paper gives a comparison of systems with mineral wool and cellular plastic, based on experience from practice and literature. It is important to look at the details in the system and at long time stability of the properties such as thermal insulation, moisture and fire. Investigation of fire properties...... insulation....

  20. Theory of Lattice Strain for Materials Undergoing Plastic Deformation

    Science.gov (United States)

    Karato, S.

    2008-12-01

    Radial x-ray diffraction is used to probe physical properties of materials including elastic and plastic properties. The theory used behind such an practice is the one developed by Singh (1993) in which the relation between lattice strain and elastic constants and macroscopic stress is derived. In this theory, the variation of inferred stress with the crystallographic planes, (hkl), is due to the elastic anisotropy. However, recent experimental studies showed that in many cases, the variation of stress with (hkl) far exceeds the value expected from this theory. I have developed a modified theory to rectify this problem with Singh's theory. In Singh's theory, the stress distribution in a polycrystalline material is treated only either unrelaxed or relaxed state. The role of plastic deformation is included only to the extent that plastic flow influences this stress state. Such an assumption corresponds to a Voigt model behavior, which is not an appropriate model at high temperatures where continuing plastic flow occurs with concurrent microscopic equilibrium, elastic deformation. This is a Maxwell model type behavior, and my model provides a stress analysis in a Maxwell material with anisotropic and non-linear power-law rheology. In this theory, the lattice strain corresponding to an imposed macroscopic strain-rate is calculated by three steps: (i) conversion of macroscopic strain-rate to macroscopic stress, (ii) conversion of macroscopic stress to microscopic stress at individual grains, and (iii) calculation of microscopic strain due to microscopic stress. The first step involves anisotropy in macroscopic viscosity that depends on anisotropy in crystal plasticity and lattice-preferred orientation. The second step involves anisotropic crystal plasticity and finally the third step involves elastic crystal anisotropy. In most cases, the influence of LPO is weak and in such a case, the lattice strain depends on (hkl) due to the anisotropy in both elastic and plastic

  1. Modeling plasticity of materials with nanostructure

    Science.gov (United States)

    Kudinova, N. R.

    2017-02-01

    A new approach to modeling of the plasticity of materials with the particle size in the range from 3 to 20 nm (nanostructure) has been proposed. It is based on classical thermodynamic approach employing the surface tension of nanoparticles. Its main advantage is the minimum number of physical parameters in use. In the context of the proposed model, we calculated the dependence of the melting temperature on the nanoparticle size which is consistent with experimental data. The volume density of the surface energy of nanoparticles was also determined. This energy is assumed to be a significant part of the internal energy during deformation Yield point was interpreted as the result of changes of grains surface energy during the deformation. The obtained yield point dependence on the grain size was related to the Hall–Petch law, and this resulted in confirmation of the hypothesis on the crucial role of surface tension forces in the initial stage of plastic deformation of nanomaterials.

  2. Mechanoelectrochemical behavior and plasticity of magnesium alloys

    Energy Technology Data Exchange (ETDEWEB)

    Eliezer, A.; Gutman, E.M.; Abramov, E.; Aghion, E. [Ben-Gurion Univ. of the Negev, Beersheba (Israel). Dept. of Materials Engineering

    1998-12-31

    The mechanical properties and mechanoelectrochemical effect (the effect of mechanical deformation on the surface electrochemical reactions) were investigated for some Mg-based alloys supposing that aluminum alloying influences them. A simple method of testing mechanoelectrochemical behavior of metals was developed. Potentiostatic polarization measurements on stressed electrode were carried out in chloride electrolyte. The correlation between the mechanoelectrochemical behavior and strain hardening stages is observed during plastic deformation. Maximum mechanoelectrochemical effect is achieved under intense strain hardening in the initial portion of this stage. The experimental observations are explained theoretically. (orig.) 9 refs.

  3. Fully plastic crack opening analyses of complex-cracked pipes for Ramberg-Osgood materials

    Energy Technology Data Exchange (ETDEWEB)

    Jeong, Jae Uk; Choi, Jae Boong [Sungkyunkwan University, Suwon (Korea, Republic of); Huh, Nam Su [Seoul National University, Seoul (Korea, Republic of); Kim, Yun Jae [Korea University, Seoul (Korea, Republic of)

    2016-04-15

    The plastic influence functions for calculating fully plastic Crack opening displacement (COD) of complex-cracked pipes were newly proposed based on systematic 3-dimensional (3-D) elastic-plastic Finite element (FE) analyses using Ramberg-Osgood (R-O) relation, where global bending moment, axial tension and internal pressure are considered separately as a loading condition. Then, crack opening analyses were performed based on GE/EPRI concept by using the new plastic influence functions for complex-cracked pipes made of SA376 TP304 stainless steel, and the predicted CODs were compared with FE results based on deformation plasticity theory of tensile material behavior. From the comparison, the confidence of the proposed fully plastic crack opening solutions for complex-cracked pipes was gained. Therefore, the proposed engineering scheme for COD estimation using the new plastic influence functions can be utilized to estimate leak rate of a complex-cracked pipe for R-O material.

  4. Effect of Austempering on Plastic Behavior of Some Austempered Ductile Iron Alloys

    OpenAIRE

    Olofsson, Jakob; Larsson, Dan; Svensson, Ingvar L

    2011-01-01

    A numerical description relating microstructure to elastic and plastic deformation behavior would make it possible to simulate the mechanical behavior of complex cast components with tailored material properties. Limited work and data have however been published regarding the connection between microstructure and plastic behavior of austempered ductile irons (ADI). In the current work the effects of austempering temperature and austempering time on the strength coefficient and the strain hard...

  5. Numerical Simulation of the Mechanical Properties and Failure of Heterogeneous Elasto-Plastic Materials

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A general numerical approach was developed to simulate the mechanical properties and the failure of heterogeneous elasto-plastic materials using statistical distributions of the material properties. An appropriate elastic-plastic constitutive relation is used to describe the material behavior and failure in each element, with a two-parameter Weibull distribution used to produce the initial heterogeneous material property variations. An adaptive incremental load-step is applied so that only one or a few elements (or integration points) change their status (i.e., from elastic to plastic, or from plastic to strain failure) within one load step. A failed element is then assigned a very small modulus to simulate the failure rather than removing it from the model, which keeps the continuity of the geometric mesh. The numerical results show that the model is suitable for simulating the effective mechanical properties and failure of heterogeneous materials with local elasto-plastic constitutive relations.

  6. Plasticizers effect on native biodegradable package materials

    Science.gov (United States)

    Cozar, Onuc; Cioica, Nicolae; Coţa, Constantin; Nagy, Elena Mihaela; Fechete, Radu

    2017-01-01

    Changes in intensity of some IR and Raman bands suggest the plasticizing - antiplasticizing effects of water and glycerol contents and a small increase of amorphous/crystalline ratio, too. The nuclear magnetic relaxation data show that the amorphous/crystalline ratio depends on amylose/amylopectin mobility and also by the place of their polymer chain segments. Thus the distributions of spin-spin (T2) relaxation times and the shift toward higher values of some T2 characteristic peaks show that the increasing of water and glycerol content in the starch package materials lead to the more mobile amylose and amylopectin polymer chain segments and the prevalence of amorphous regions in the prepared native corn starch samples.

  7. Elastic, plastic, and fracture mechanisms in graphene materials.

    Science.gov (United States)

    Daniels, Colin; Horning, Andrew; Phillips, Anthony; Massote, Daniel V P; Liang, Liangbo; Bullard, Zachary; Sumpter, Bobby G; Meunier, Vincent

    2015-09-23

    In both research and industry, materials will be exposed to stresses, be it during fabrication, normal use, or mechanical failure. The response to external stress will have an important impact on properties, especially when atomic details govern the functionalities of the materials. This review aims at summarizing current research involving the responses of graphene and graphene materials to applied stress at the nanoscale, and to categorize them by stress-strain behavior. In particular, we consider the reversible functionalization of graphene and graphene materials by way of elastic deformation and strain engineering, the plastic deformation of graphene oxide and the emergence of such in normally brittle graphene, the formation of defects as a response to stress under high temperature annealing or irradiation conditions, and the properties that affect how, and mechanisms by which, pristine, defective, and polycrystalline graphene fail catastrophically during fracture. Overall we find that there is significant potential for the use of existing knowledge, especially that of strain engineering, as well as potential for additional research into the fracture mechanics of polycrystalline graphene and device functionalization by way of controllable plastic deformation of graphene.

  8. Damage evolution of metallic materials during high temperature plastic deformation

    Institute of Scientific and Technical Information of China (English)

    汪凌云; 刘雪峰; 汤爱涛; 黄光杰

    2002-01-01

    The damage evolution of high temperature plastic deformation of metallic materials was studied by use of continuum damage mechanics (CDM) theory. Based on thermodynamics, on a damage variable D and Zener-Hollomon parameter Z, and on the effective stress concept, a damage evolution model of high temperature plastic deformation was derived and was used to analyze the damage evolution of 1420 Al-Li alloy during high temperature plastic deformation. The model that is verified by tests can also be applied to the materials that are loaded prorata or out of proportion during high temperature plastic deformation. It extends the applied scope of damage mechanics.

  9. Model for charge/discharge-rate-dependent plastic flow in amorphous battery materials

    Science.gov (United States)

    Khosrownejad, S. M.; Curtin, W. A.

    2016-09-01

    Plastic flow is an important mechanism for relaxing stresses that develop due to swelling/shrinkage during charging/discharging of battery materials. Amorphous high-storage-capacity Li-Si has lower flow stresses than crystalline materials but there is evidence that the plastic flow stress depends on the conditions of charging and discharging, indicating important non-equilibrium aspects to the flow behavior. Here, a mechanistically-based constitutive model for rate-dependent plastic flow in amorphous materials, such as LixSi alloys, during charging and discharging is developed based on two physical concepts: (i) excess energy is stored in the material during electrochemical charging and discharging due to the inability of the amorphous material to fully relax during the charging/discharging process and (ii) this excess energy reduces the barriers for plastic flow processes and thus reduces the applied stresses necessary to cause plastic flow. The plastic flow stress is thus a competition between the time scales of charging/discharging and the time scales of glassy relaxation. The two concepts, as well as other aspects of the model, are validated using molecular simulations on a model Li-Si system. The model is applied to examine the plastic flow behavior of typical specimen geometries due to combined charging/discharging and stress history, and the results generally rationalize experimental observations.

  10. VISCO-ELASTIC (PLASTIC) EFFECTS AND FAILURE BEHAVIOR OF PUR FOAMED PLASTICS

    Institute of Scientific and Technical Information of China (English)

    1998-01-01

    The viscous effects and failure behavior of PUR foamed plastics are investigated by the cycling loading and preloading experiments. On the basis of static and dynamic compressive experiments, the SEM analysis is given for the PUR foamed plastics specimens which have been tested and the deformation as well as failure mechanisms are determined at the same time. In addition, the relaxation characteristics and the failure criterion of foamed plastics are discussed adequately.

  11. Hysteretic behavior modeling of elastoplastic materials

    Directory of Open Access Journals (Sweden)

    Šumarac Dragoslav

    2008-01-01

    Full Text Available In the present paper the Preisach model of hysteresis is applied to model cyclic behavior of elasto-plastic material. Rate of loading and viscous effects will not be considered. The problem of axial loading of rectangular cross section and cyclic bending of rectangular tube (box will be studied in details. Hysteretic stress-strain loop for prescribed history of stress change is plotted for material modeled by series connection of three unite element. Also moment-curvature hysteretic loop is obtained for a prescribed curvature change of rectangular tube (box. One chapter of the paper is devoted to results obtained by FEM using Finite Element Code ABAQUS. All obtained results clearly show advantages of the Preisach model for describing cyclic behavior of elasto-plastic material.

  12. Photoconversion of gasified organic materials into biologically-degradable plastics

    Science.gov (United States)

    Weaver, Paul F.; Maness, Pin-Ching

    1993-01-01

    A process is described for converting organic materials (such as biomass wastes) into a bioplastic suitable for use as a biodegradable plastic. In a preferred embodiment the process involves thermally gasifying the organic material into primarily carbon monoxide and hydrogen, followed by photosynthetic bacterial assimilation of the gases into cell material. The process is ideally suited for waste recycling and for production of useful biodegradable plastic polymer.

  13. Photoconversion of gasified organic materials into biologically-degradable plastics

    Energy Technology Data Exchange (ETDEWEB)

    Weaver, P.F.; Pinching Maness.

    1993-10-05

    A process is described for converting organic materials (such as biomass wastes) into a bioplastic suitable for use as a biodegradable plastic. In a preferred embodiment the process involves thermally gasifying the organic material into primarily carbon monoxide and hydrogen, followed by photosynthetic bacterial assimilation of the gases into cell material. The process is ideally suited for waste recycling and for production of useful biodegradable plastic polymer. 3 figures.

  14. Plastic evolution behavior of H340LAD_Z steel by an optical method

    Science.gov (United States)

    Guo, Nan; Liang, Jin; Yu, Qiang; Qian, Boxing

    2017-02-01

    An optical method based on digital image correlation (DIC) technology was proposed to measure the plastic evolution of the high-strength low alloy steel H340LAD_Z. The basic principle of DIC technology is introduced, and then, the use of a 3D deformation measurement system and electronic universal testing machine to dynamically measure plastic evolution during the tensile yield stage is described. Through the full-field full-process measurement of plastic deformation during the yield stage in the 0°, 45° and 90° loading directions, the plastic evolution law was revealed. The results demonstrate that the proposed 3D DIC method can accurately reveal the starting and ending times for plastic evolution. The specimens in the three directions exhibit different plastic evolution behaviors, although they have similar yield strengths and yield times. The specimens in the 45° and 90° loading directions began to enter plastic deformation from bottom to top and the plastic area was maintained in a constant deformed state, while the evolution behavior in the 0° direction transited from both sides to the middle and plastic deformation was uneven. It is important to study plastic evolution of a metal sheet to determine the material properties and to provide an accurate basis for finite element modeling.

  15. Plastic evolution behavior of H340LAD-Z steel by an optical method

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Nan; Liang, Jin; Yu, Qiang; Qian, Boxing

    2017-02-01

    An optical method based on digital image correlation (DIC) technology was proposed to measure the plastic evolution of the high-strength low alloy steel H340LAD-Z. The basic principle of DIC technology is introduced, and then, the use of a 3D deformation measurement system and electronic universal testing machine to dynamically measure plastic evolution during the tensile yield stage is described. Through the full-field full-process measurement of plastic deformation during the yield stage in the 0°, 45° and 90° loading directions, the plastic evolution law was revealed. The results demonstrate that the proposed 3D DIC method can accurately reveal the starting and ending times for plastic evolution. The specimens in the three directions exhibit different plastic evolution behaviors, although they have similar yield strengths and yield times. The specimens in the 45° and 90° loading directions began to enter plastic deformation from bottom to top and the plastic area was maintained in a constant deformed state, while the evolution behavior in the 0° direction transited from both sides to the middle and plastic deformation was uneven. It is important to study plastic evolution of a metal sheet to determine the material properties and to provide an accurate basis for finite element modeling.

  16. Stress Wave Propagation in Viscoelastic-Plastic Rock-Like Materials

    Directory of Open Access Journals (Sweden)

    Liu Lang

    2016-05-01

    Full Text Available Rock-like materials are composites that can be regarded as a mixture composed of elastic, plastic, and viscous components. They exhibit viscoelastic-plastic behavior under a high-strain-rate loading according to element model theory. This paper presents an analytical solution for stress wave propagation in viscoelastic-plastic rock-like materials under a high-strain-rate loading and verifies the solution through an experimental test. A constitutive equation of viscoelastic-plastic rock-like materials was first established, and then kinematic and kinetic equations were then solved to derive the analytic solution for stress wave propagation in viscoelastic-plastic rock-like materials. An experimental test using the SHPB (Split Hopkinson Pressure Bar for a concrete specimen was conducted to obtain a stress-strain curve under a high-strain-rate loading. Inverse analysis based on differential evolution was conducted to estimate undetermined variables for constitutive equations. Finally, the relationship between the attenuation factor and the strain rate in viscoelastic-plastic rock-like materials was investigated. According to the results, the frequency of the stress wave, viscosity coefficient, modulus of elasticity, and density play dominant roles in the attenuation of the stress wave. The attenuation decreases with increasing strain rate, demonstrating strongly strain-dependent attenuation in viscoelastic-plastic rock-like materials.

  17. Thermal image analysis of plastic deformation and fracture behavior by a thermo-video measurement system

    Science.gov (United States)

    Ohbuchi, Yoshifumi; Sakamoto, Hidetoshi; Nagatomo, Nobuaki

    2016-12-01

    The visualization of the plastic region and the measurement of its size are necessary and indispensable to evaluate the deformation and fracture behavior of a material. In order to evaluate the plastic deformation and fracture behavior in a structural member with some flaws, the authors paid attention to the surface temperature which is generated by plastic strain energy. The visualization of the plastic deformation was developed by analyzing the relationship between the extension of the plastic deformation range and the surface temperature distribution, which was obtained by an infrared thermo-video system. Furthermore, FEM elasto-plastic analysis was carried out with the experiment, and the effectiveness of this non-contact measurement system of the plastic deformation and fracture process by a thermography system was discussed. The evaluation method using an infrared imaging device proposed in this research has a feature which does not exist in the current evaluation method, i.e. the heat distribution on the surface of the material has been measured widely by noncontact at 2D at high speed. The new measuring technique proposed here can measure the macroscopic plastic deformation distribution on the material surface widely and precisely as a 2D image, and at high speed, by calculation from the heat generation and the heat propagation distribution.

  18. Associated computational plasticity schemes for nonassociated frictional materials

    DEFF Research Database (Denmark)

    Krabbenhoft, K.; Karim, M. R.; Lyamin, A. V.;

    2012-01-01

    A new methodology for computational plasticity of nonassociated frictional materials is presented. The new approach is inspired by the micromechanical origins of friction and results in a set of governing equations similar to those of standard associated plasticity. As such, procedures previously...

  19. Research on application of plastic materials in cars

    Institute of Scientific and Technical Information of China (English)

    Jin Jianwei; Ma Fangwu; Liu Qiang; Wu Tiannan; Dong Ningning; Zhao Fuguan; Ma Mingtu; Guo Yihui

    2012-01-01

    This paper gives analysis of application status and prospect of plastic materials from the aspects of applied ma- terial amount comparison, development of new materials & new technologies, lightweight, design conception of new components, recyclability, simplification and diversity of materials, standardization of material specification and pres- ents corresponding conclusions and suggestions.

  20. Elasto-plastic constitutive modeling for granular materials

    Institute of Scientific and Technical Information of China (English)

    彭芳乐; 李建中

    2004-01-01

    Based on the modified plastic strain energy approach, an elasto-plastic constitutive modeling for sand was proposed. The hardening function between the modified plastic strain energy and a stress parameter was presented, which was independent of stress history and stress paths. The proposed model was related to an isotropically work-hardening and softening, non-associated and elasto-plastic material description. It is shown that the constitutive modeling, the inherent and stress system-induced cross-anisotropic elasticity is also considered. The constitutive model is capable of simulating the effects on the deformation characteristics of stress history and stress path, pressure level and anisotropic strength.

  1. Stress Dependence of Transformation Plastic Behavior

    Institute of Scientific and Technical Information of China (English)

    Tatsuo Inoue

    2004-01-01

    Transformation plasticity is known to play an important role in the course of heat treatment processes, and so affect the results of heat treatment simulations, which means that the transformation plasticity coefficient is necessary to be identifies. The authors developed a new method by use of four-point bending system of a beam to identify transformation plasticity coefficient taking advantage of its easiness and high accuracy compared with other conventional methods like tension test, etc., and identified the coefficient for four kinds of steels; plane carbon steel, Cr-steel, Cr-Mo steel and bearing steel. In this paper, further experimental data are presented for the steels if the coefficient Kp during pearlite transformation depend on the applied stress. Obtained results reveals that the stress dependence of Kp is rather trivial except for uncertain tendency detected in plane carbon steel. The relation between the Kp and carbon content included is

  2. The notion of a plastic material spin in atomistic simulations

    Science.gov (United States)

    Dickel, D.; Tenev, T. G.; Gullett, P.; Horstemeyer, M. F.

    2016-12-01

    A kinematic algorithm is proposed to extend existing constructions of strain tensors from atomistic data to decouple elastic and plastic contributions to the strain. Elastic and plastic deformation and ultimately the plastic spin, useful quantities in continuum mechanics and finite element simulations, are computed from the full, discrete deformation gradient and an algorithm for the local elastic deformation gradient. This elastic deformation gradient algorithm identifies a crystal type using bond angle analysis (Ackland and Jones 2006 Phys. Rev. B 73 054104) and further exploits the relationship between bond angles to determine the local deformation from an ideal crystal lattice. Full definitions of plastic deformation follow directly using a multiplicative decomposition of the deformation gradient. The results of molecular dynamics simulations of copper in simple shear and torsion are presented to demonstrate the ability of these new discrete measures to describe plastic material spin in atomistic simulation and to compare them with continuum theory.

  3. PLASTIC MATERIALS IN EUROPEAN AGRICULTURE: ACTUAL USE AND PERSPECTIVES

    Directory of Open Access Journals (Sweden)

    Giacomo Scarascia-Mugnozza

    2012-06-01

    Full Text Available The world consumption of plastics in agriculture amounts yearly to 6.5 million tons. In addition to conventional polymers used in agriculture for greenhouses and mulches such as PE, PVC, EVA, photo-selective and luminescent polymers have been used, in order to improve the quality of crops. For the same reason plastic nets are used mainly in countries with tropical and Mediterranean climates. For an environmentally friendly agricultural activity, an alternative strategy can be represented by bio-based agricultural raw materials. For low environmental impact applications, biodegradable materials for agricultural films are nowadays produced. An overview of the main methods for the disposal and recycling of plastic materials are presented with the results of mechanical and radiometric tests on recycled plastics. The strategies to reduce the burden of plastics in agriculture are: a correct procedure for the collection, disposal and recycling of post-consumption plastics; the increase of lifetime duration and performance; and the introduction and promotion of bio-based materials.

  4. Radiation degradation of plastic insulating materials

    Science.gov (United States)

    Bartoníček, B.; Hnát, V.; Janovský, I.; Pejša, R.

    1995-02-01

    Several types of polymeric compounds, used as insulating and sheathing materials of cables, were subjected to accelerated thermal and radiation ageing and to LOCA test. The stability of materials was evaluated via their mechanical properties, namely strain at break.

  5. Spallation products induced by energetic neutrons in plastic detector material

    CERN Document Server

    Grabisch, K; Enge, W; Scherzer, R

    1977-01-01

    Cellulose nitrate plastic detector sheets were irradiated with secondary neutrons of the 22 GeV/c proton beam at the CERN accelerator. He, Li and Be particles which are produced in nuclear interactions of the neutrons with the target elements C, N and O of the plastic detector material are measured. Preliminary angle and range distributions and isotropic abundances of the secondary particles are discussed. (6 refs).

  6. [Carbon fiber-reinforced plastics as implant materials].

    Science.gov (United States)

    Bader, R; Steinhauser, E; Rechl, H; Siebels, W; Mittelmeier, W; Gradinger, R

    2003-01-01

    Carbon fiber-reinforced plastics have been used clinically as an implant material for different applications for over 20 years.A review of technical basics of the composite materials (carbon fibers and matrix systems), fields of application,advantages (e.g., postoperative visualization without distortion in computed and magnetic resonance tomography), and disadvantages with use as an implant material is given. The question of the biocompatibility of carbon fiber-reinforced plastics is discussed on the basis of experimental and clinical studies. Selected implant systems made of carbon composite materials for treatments in orthopedic surgery such as joint replacement, tumor surgery, and spinal operations are presented and assessed. Present applications for carbon fiber reinforced plastics are seen in the field of spinal surgery, both as cages for interbody fusion and vertebral body replacement.

  7. Particulate Filled Composite Plastic Materials from Recycled Glass Fibre Reinforced Plastics

    Directory of Open Access Journals (Sweden)

    Aare ARUNIIT

    2011-09-01

    Full Text Available Glass fibre reinforced plastic (GFRP scrap consisted of acrylic plastic with glass fibre reinforcement in polyester resin matrix was used in our experiments. The multi-functional DS-series disintegrator mills were used for mechanical processing of GFRP scrap. Preceding from the results characterization of the milled powder particles size, shape and other properties the numerical algorithm for modelling of the density of the new filler material was developed. The main goal of the current study is to develop new particulate filled composite plastic material from recycled GFRP scrap. With recovered plastic powder material the higher filler content in polyester resin matrix can be achieved. The new composite is modelled on basis of the properties of new material. Such an approach requires tests of the new material. The considered target characteristics of the new material are the tensile strength, elongation at break and the cost. The multicriteria optimization problem has been formulated and solved by use of physical programming techniques and Pareto optimality concept. The designed new composites were manufactured in different mixing ratios of powder and binder agent. The strength and stiffness properties of new composite material were tested. http://dx.doi.org/10.5755/j01.ms.17.3.593

  8. A plastic micropump constructed with conventional techniques and materials

    NARCIS (Netherlands)

    Bohm, Sebastian; Olthuis, Wouter; Bergveld, P.

    1999-01-01

    A plastic micropump which can be produced using conventional production techniques and materials is presented. By applying well-known techniques and materials, economic fabrication of micropumps for various applications is feasible even at low production volumes. The micropump is capable of pumping

  9. Energetic materials: crystallization, characterization and insensitive plastic bonded explosives

    NARCIS (Netherlands)

    Heijden, A.E.D.M. van der; Creyghton, Y.L.M.; Marino, E.; Bouma, R.H.B.; Scholtes, G.J.H.G.; Duvalois, W.; Roelands, C.P.M.

    2008-01-01

    The product quality of energetic materials is predominantly determined by the crystallization process applied to produce these materials. It has been demonstrated in the past that the higher the product quality of the solid energetic ingredients, the less sensitive a plastic bonded explosive contain

  10. Energetic materials: crystallization, characterization and insensitive plastic bonded explosives

    NARCIS (Netherlands)

    Heijden, A.E.D.M. van der; Creyghton, Y.L.M.; Marino, E.; Bouma, R.H.B.; Scholtes, G.J.H.G.; Duvalois, W.; Roelands, C.P.M.

    2008-01-01

    The product quality of energetic materials is predominantly determined by the crystallization process applied to produce these materials. It has been demonstrated in the past that the higher the product quality of the solid energetic ingredients, the less sensitive a plastic bonded explosive

  11. Single crystal plasticity by modeling dislocation density rate behavior

    Energy Technology Data Exchange (ETDEWEB)

    Hansen, Benjamin L [Los Alamos National Laboratory; Bronkhorst, Curt [Los Alamos National Laboratory; Beyerlein, Irene [Los Alamos National Laboratory; Cerreta, E. K. [Los Alamos National Laboratory; Dennis-Koller, Darcie [Los Alamos National Laboratory

    2010-12-23

    The goal of this work is to formulate a constitutive model for the deformation of metals over a wide range of strain rates. Damage and failure of materials frequently occurs at a variety of deformation rates within the same sample. The present state of the art in single crystal constitutive models relies on thermally-activated models which are believed to become less reliable for problems exceeding strain rates of 10{sup 4} s{sup -1}. This talk presents work in which we extend the applicability of the single crystal model to the strain rate region where dislocation drag is believed to dominate. The elastic model includes effects from volumetric change and pressure sensitive moduli. The plastic model transitions from the low-rate thermally-activated regime to the high-rate drag dominated regime. The direct use of dislocation density as a state parameter gives a measurable physical mechanism to strain hardening. Dislocation densities are separated according to type and given a systematic set of interactions rates adaptable by type. The form of the constitutive model is motivated by previously published dislocation dynamics work which articulated important behaviors unique to high-rate response in fcc systems. The proposed material model incorporates thermal coupling. The hardening model tracks the varying dislocation population with respect to each slip plane and computes the slip resistance based on those values. Comparisons can be made between the responses of single crystals and polycrystals at a variety of strain rates. The material model is fit to copper.

  12. Fracture of anisotropic materials with plastic strain-gradient effects

    DEFF Research Database (Denmark)

    Legarth, Brian Nyvang

    2013-01-01

    parameter is adopted. The fracture process along the fiber-matrix interface is modeled using a recently proposed cohesive law extension having an additional material length parameter. Due to the fiber-matrix fracture a sudden stress-drop is seen in the macroscopic stress-strain response which defines......A unit cell is adopted to numerically analyze the effect of plastic anisotropy on frac-ture evolution in a micro-reinforced fiber-composite. The matrix material exhibit size-effects and an anisotropic strain-gradient plasticity model accounting for such size-effects through a mate-rial length scale...... the failure strain of the composite. The effect of the two material length parameters on the failure strain of the composite is studied. For small values of the material length scale parameter conventional predictions are obtained. Larger values of the material length scale parameter result in corresponding...

  13. Plastic raw materials in Neolithic pottery production

    Directory of Open Access Journals (Sweden)

    Alexander A. Bobrinsky

    2012-12-01

    Full Text Available The paper is dedicated to the investigation of various natural silts as the most ancient type of raw material used in pottery production. The authors describe the specific features of the composition of plain and mountain silts, and discover the same features in ancient ceramics from different regions in Russia. It can be concluded that silts were the earliest raw material used, a tradition that faded away during the evolution of pottery production.

  14. Bending behavior of lapped plastic ehv cables

    Energy Technology Data Exchange (ETDEWEB)

    Morgan, G H; Muller, A C

    1980-01-01

    One of the factors delaying the development of lapped polymeric cables has been their reputed poor bending characteristics. Complementary programs were begun at BNL several years ago to mathematically model the bending of synthetic tape cables and to develop novel plastic tapes designed to have moduli more favorable to bending. A series of bend tests was recently completed to evaluate the bending performance of several tapes developed for use in experimental superconducting cables. The program is discussed and the results of the bend tests are summarized.

  15. A PVC-foam material model based on a thermodynamically elasto-plastic-damage framework exhibiting failure and crushing

    NARCIS (Netherlands)

    Gielen, A.W.J.

    2008-01-01

    A well known foam for naval sandwiches is PVC (polyvinyl chloride) foam. This foam exhibits elasto-damage behavior under tension and elasto-plastic behavior under compression. A proper material model is required for the prediction of the failure and post-failure behavior of these sandwiches during (

  16. Becoming a mother-circuit plasticity underlying maternal behavior.

    Science.gov (United States)

    Elyada, Yishai M; Mizrahi, Adi

    2015-12-01

    The transition to motherhood is a dramatic event during the lifetime of many animals. In mammals, motherhood is accompanied by hormonal changes in the brain that start during pregnancy, followed by experience dependent plasticity after parturition. Together, these changes prime the nervous system of the mother for efficient nurturing of her offspring. Recent work has described how neural circuits are modified during the transition to motherhood. Here we discuss changes in the auditory cortex during motherhood as a model for maternal plasticity in sensory systems. We compare classical plasticity paradigms with changes that arise naturally in mothers, highlighting current efforts to establish a mechanistic understanding of plasticity and its different components in the context of maternal behavior.

  17. Plastic plus stainless-steel fibers make resilient, impermeable material

    Science.gov (United States)

    Smirra, J. R.

    1965-01-01

    Plastic material combined with stainless-steel fibers and molded under heat and pressure into a desired configuration is both soft enough to deform under a load and resilient enough to return to its original shape when the load is removed.

  18. Experimental investigation and numerical simulation of plastic flow behavior during forward-backward-radial extrusion process

    OpenAIRE

    A. Farhoumand; R. Ebrahimi

    2016-01-01

    Finite element method was employed to investigate the effect of process parameters of plastic deformation behavior in Forward-Backward-Radial Extrusion (FBRE) process. The result of an axisymmetric model shows that the friction between die components and the sample has a substantial effect on the material flow behavior. Although strain heterogeneity index (SHI) slightly decreases with an increase in friction, large portion of the sample experiences significant strain heterogeneity. Increasing...

  19. Materials Behavior Research Laboratory

    Data.gov (United States)

    Federal Laboratory Consortium — The purpose is to evaluate mechanical properties of materials including metals, intermetallics, metal-matrix composites, and ceramic-matrix composites under typical...

  20. Stress, stress hormones, and the behavioral neurobiology of brain plasticity

    NARCIS (Netherlands)

    Bohus, B; Luiten, PGM; Beldhuis, HJA; vanderZee, EA; Roozendaal, B; Douma, B; Ishikawa, K; McGaugh, JL; Sakata, H

    1996-01-01

    Efforts have long been directed toward studying stress-induced alterations via stress hormones on brain excitability and synaptic plasticity as inferred from combined behavioral, electrophysiological, and immunohistochemical cellular/molecular observations. Kindling of the brain in the rat serves as

  1. Energy dissipation and contour integral characterizing fracture behavior of incremental plasticity

    Institute of Scientific and Technical Information of China (English)

    Qi-Lin He; Lin-Zhi Wu; Ming Li; Hong-Bo Chen

    2011-01-01

    Jep-integral is derived for characterizing the fracture behavior of elastic-plastic materials. The Jep-integral differs from Rice's J-integral in that the free energy density rather than the stress working density is employed to define energy-momentum tensor. The Jep-integral is proved to be path-dependent regardless of incremental plasticity and deformation plasticity. The Jep-integral possesses clearly clear physical meaning: (1) the value Jeptjp evaluated on the infinitely small contour surrounding the crack tip represents the crack tip energy dissipation; (2) when the global steadystate crack growth condition is approached, the value of Jepfar-ss calculated along the boundary contour equals to the sum of crack tip dissipation and bulk dissipation of plastic zone. The theoretical results are verified by simulating mode I crack problems.

  2. The impact of synapsins on synaptic plasticity and cognitive behaviors

    Institute of Scientific and Technical Information of China (English)

    Lin ZHANG; Zhong-Xin ZHAO

    2006-01-01

    Synapsins are a family of phosphoproteins specifically associated with the cytoplasmic surface of the synaptic vesicle membrane, appearing to regulate neurotransmitter release, the formation and maintenance of synaptic contacts.They could induce the change of the synaptic plasticity to regulate various adaptation reactions, and change the cognitive behaviors. So we presume that if some cognitive behavior are damaged, synapsins would be changed as well. This gives us a new recognition of better diagnosis and therapy of cognitive disorder desease.

  3. Chronic alcohol alters rewarded behaviors and striatal plasticity

    OpenAIRE

    DePoy, Lauren; Daut, Rachel; Wright, Tara; Camp, Marguerite; Crowley, Nicole; Noronha, Bianca; Lovinger, David; Holmes, Andrew

    2014-01-01

    Chronic intermittent ethanol (CIE) alters neural functions and behaviors mediated by the dorsolateral striatum (DLS) and prefrontal cortex. Here, we examined the effects of prolonged (16-bout) CIE on DLS plasticity and DLS-mediated behaviors. Ex vivo electrophysiological recordings revealed loss in efficacy of DLS synaptically induced activation and absent long-term depression after CIE. CIE increased two-bottle choice drinking and impaired Pavlovian-to-instrumental transfer but not discrimin...

  4. [Mutual relations between plastic materials and bacteria (author's transl)].

    Science.gov (United States)

    Toepfer, C T; Kanz, E

    1976-12-01

    The complex problems of microbiological degradation of synthetic plastics and a fairly wide variety of 62 testing materials, belonging to 14 major groups of plastics, are described. Adaequate and reliable testing techniques had to be devised. Drawing on the experiences of H. Braun, 1930, and of Bushnell and Haas, 1941, as to the metabolism of bacteria and the utilization of certain hydrocarbons by microorganisms, and previous research work by A. Schwartz in Berlin, 1959-60, on microbial corrosion of plastics, methods of laboratory testing were developed. The bacteriological technique was based on selection of aerobic microorganisms, which were, by starvation, adapted to use the plastic materials as their only carbon source; foreign carbon sources had to be strictly eliminated; emphasis was laid on proper, double control cultures. The test organisms involved included P. aeruginosa and fluorescens strains, also a certain species of Candida, and mixtures of soil, sewage and garbage organisms grown on exposed plastic surfaces. By means of series of passages the selective adaptation and conservation of these organisms was continued up to 4 1/2 years. An anaerobic adaptation method for Desulfovibrio desulfuricans was developed and used successfully. After preliminary experimentation (Soil burial, sewage and garbage exposure tests) in the laboratory as well as in the open, a large scale Field testing programme under realistic and to some extent extreme conditions was implemented: Nine different plastic materials comprising eight plain high polymer plastics and for comparison one synthetic Cellulose derivate, together with glass control samples, were exposed in twelve different sewage, garbage, and soil media over a period of 3 months to 2 years, and subsequently examined. On the basis of the bacteriological results obtained from the adaptation series the test materials were classified into three categories, corresponding to the stimulation of bacterial growth: Group one

  5. Standard Guide for Testing Materials for Aerospace Plastic Transparent Enclosures

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2008-01-01

    1.1 This guide is intended to summarize the standard test methods available on individual and composite materials utilized in fabrication of aerospace plastic transparent enclosures. As such, it is intended to specifically include transparent thermoplastics, transparent elastomers, and reinforced plastics, whether thermoplastic or thermosetting. 1.2 This guide is intended as an aid in the search for test methods pertinent to Aerospace Plastic Transparent Enclosures. It should be understood that all methods listed may not apply to all enclosures. 1.3 The standards included refer to the properties or aspects listed in Table 1. The properties or aspects are listed in alphabetical order and the descriptions used are intended to facilitate the search. 1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limi...

  6. Experimental investigations and numerical simulations of notch effect in cellular plastic materials

    Science.gov (United States)

    Marsavina, L.; Linul, E.; Voiconi, T.; Negru, R.

    2016-04-01

    Cellular plastics are light weight structures with many applications in civil, aeronautical, automotive and mechanical engineering. Properties of cellular materials depend on the properties of the solid material, on the shape and dimensions of the cellular structure and on the relative density of the cellular material. Most of cellular plastic materials are crushing in compression and have a brittle behavior in tension. The effect of notches represents an important issue in such materials, taking into account that for packing applications for example, notches/holes should be introduced in the cellular material. This paper investigates the effect of notches in compression for three different densities 100, 145 and 300 kg/m3 polyurethane (PUR) foams. Experimental investigations were performed on rectangular blocks of 100×100×25 mm with 16, 28 and 40 mm central holes. The mechanism of damage was monitored with an IR camera FLIR A40M. Purpose of the numerical simulations was to calibrate a material model, based on compression test for un-notched specimens using the CRUSHABLE FOAM models implemented in ABAQUS SIMULIA. Then the material models were used to simulate the experimental tests on notched blocks. Good agreement was obtained for the load - displacement curves obtained experimentally and from simulation. Also the plastic deformation patterns observed experimentally by IR thermograpghy were obtained numerically using the CRUSHABLE FOAM material model.

  7. Healing behavior of preexisting hydrogen micropores in aluminum alloys during plastic deformation

    Energy Technology Data Exchange (ETDEWEB)

    Toda, H., E-mail: toda@pse.tut.ac.jp [Department of Production Systems Engineering, Toyohashi University of Technology, Toyohashi, Aichi 441-8580 (Japan); Minami, K. [Department of Production Systems Engineering, Toyohashi University of Technology, Toyohashi, Aichi 441-8580 (Japan); Koyama, K.; Ichitani, K. [Furukawa-Sky Aluminum Corp., 1351, Uwanodai, Fukaya, Saitama 366-8511 (Japan); Kobayashi, M. [Department of Production Systems Engineering, Toyohashi University of Technology, Toyohashi, Aichi 441-8580 (Japan); Uesugi, K.; Suzuki, Y. [Japan Synchrotron Radiation Research Institute, Mikazuki-cho, Sayo-gun, Hyogo 679-5198 (Japan)

    2009-09-15

    Synchrotron X-ray microtomography was used to observe the shrinkage and annihilation behaviors of hydrogen micropores in three dimensions during hot and cold plastic deformation of an Al-Mg alloy. Whether complete healing of micropores is achieved after plastic deformation was examined by exposing the material to a high temperature after plastic deformation. Although micropores generally show a pattern of shrinking and closing, closer inspection of a single specimen revealed a variety of geometrically variable behaviors. It is noteworthy that some of the micropores are reinitiated in positions identical to those before their annihilation, even after an 8-22% macroscopic strain has been further applied after annihilation. We attribute local variations such as these to significant local strain variation, which we measured in a series of tomographic volumes by tracking the microstructural features.

  8. Neural plasticity and behavior - sixty years of conceptual advances.

    Science.gov (United States)

    Sweatt, J David

    2016-10-01

    This brief review summarizes 60 years of conceptual advances that have demonstrated a role for active changes in neuronal connectivity as a controller of behavior and behavioral change. Seminal studies in the first phase of the six-decade span of this review firmly established the cellular basis of behavior - a concept that we take for granted now, but which was an open question at the time. Hebbian plasticity, including long-term potentiation and long-term depression, was then discovered as being important for local circuit refinement in the context of memory formation and behavioral change and stabilization in the mammalian central nervous system. Direct demonstration of plasticity of neuronal circuit function in vivo, for example, hippocampal neurons forming place cell firing patterns, extended this concept. However, additional neurophysiologic and computational studies demonstrated that circuit development and stabilization additionally relies on non-Hebbian, homoeostatic, forms of plasticity, such as synaptic scaling and control of membrane intrinsic properties. Activity-dependent neurodevelopment was found to be associated with cell-wide adjustments in post-synaptic receptor density, and found to occur in conjunction with synaptic pruning. Pioneering cellular neurophysiologic studies demonstrated the critical roles of transmembrane signal transduction, NMDA receptor regulation, regulation of neural membrane biophysical properties, and back-propagating action potential in critical time-dependent coincidence detection in behavior-modifying circuits. Concerning the molecular mechanisms underlying these processes, regulation of gene transcription was found to serve as a bridge between experience and behavioral change, closing the 'nature versus nurture' divide. Both active DNA (de)methylation and regulation of chromatin structure have been validated as crucial regulators of gene transcription during learning. The discovery of protein synthesis dependence on the

  9. Effect of Austempering on Plastic Behavior of Some Austempered Ductile Iron Alloys

    Science.gov (United States)

    Olofsson, Jakob; Larsson, Dan; Svensson, Ingvar L.

    2011-12-01

    A numerical description relating microstructure to elastic and plastic deformation behavior would make it possible to simulate the mechanical behavior of complex cast components with tailored material properties. Limited work and data, however, have been published regarding the connection between microstructure and plastic behavior of austempered ductile irons (ADIs). In the current work, the effects of austempering temperature and austempering time on the strength coefficient and the strain hardening exponent of the Hollomon equation were investigated for two ADI alloys. The results show that the plastic behavior is highly dependent on the combination of austempering temperature and austempering time. It was found that as the austempering temperature increases, both the strength coefficient and the strain hardening exponent initially decrease, but after reaching a minimum at the critical austempering temperature, they show a plateau or an increase. The effect of the austempering time on the plastic behavior depends on the austempering temperature. At low austempering temperatures, the strength coefficient and the strain hardening exponent decrease with increased austempering time, whereas at higher austempering temperatures, they show little time dependence. These relations are explained by the microstructural transformations that take place during the austempering heat treatment.

  10. Automobile materials competition: energy implications of fiber-reinforced plastics

    Energy Technology Data Exchange (ETDEWEB)

    Cummings-Saxton, J.

    1981-10-01

    The embodied energy, structural weight, and transportation energy (fuel requirement) characteristics of steel, fiber-reinforced plastics, and aluminum were assessed to determine the overall energy savings of materials substitution in automobiles. In body panels, a 1.0-lb steel component with an associated 0.5 lb in secondary weight is structurally equivalent to a 0.6-lb fiber-reinforced plastic component with 0.3 lb in associated secondary weight or a 0.5-lb aluminum component with 0.25 lb of secondary weight. (Secondary weight refers to the combined weight of the vehicle's support structure, engine, braking system, and drive train, all of which can be reduced in response to a decrease in total vehicle weight.) The life cycle transportation energy requirements of structurally equivalent body panels (including their associated secondary weights) are 174.4 x 10/sup 3/ Btu for steel, 104.6 x 10/sup 3/ Btu for fiber-reinforced plastics, and 87.2 x 10/sup 3/ Btu for aluminum. The embodied energy requirements are 37.2 x 10/sup 3/ Btu for steel, 22.1 x 10/sup 3/ Btu for fiber-reinforced plastics, and 87.1 x 10/sup 3/ Btu for aluminum. These results can be combined to yield total energy requirements of 211.6 x 10/sup 3/ Btu for steel, 126.7 x 10/sup 3/ Btu for fiber-reinforced plastics, and 174.3 x 10/sup 3/ Btu for aluminum. Fiber-reinforced plastics offer the greatest improvements over steel in both embodied and total energy requirements. Aluminum achieves the greatest savings in transportation energy.

  11. Strength of anisotropic wood and synthetic materials. [plywood, laminated wood plastics, glass fiber reinforced plastics, polymeric film, and natural wood

    Science.gov (United States)

    Ashkenazi, Y. K.

    1981-01-01

    The possibility of using general formulas for determining the strength of different anisotropic materials is considered, and theoretical formulas are applied and confirmed by results of tests on various nonmetallic materials. Data are cited on the strength of wood, plywood, laminated wood plastics, fiber glass-reinforced plastics and directed polymer films.

  12. Influence of Inclusion Shape on Thermoelasto-Plastic Optimun Design of Ceramic Metal Functionally Graded Materials

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A nonlinear finite element method is applied to observe how inclusion shape influence the thermal response of a ceramic-metal functionally graded material (FGM).The elastic and plastic behaviors of the layers which are two-phase isotropic composites consisting of randomly oriented elastic spheroidal inclusions and a ductile matrix are predicted by a mean field method.The prediction results show that inclusion shape has remarkable influence on the overall behavior of the composite.The consequences of the thermal response analysis of the FGM are that the response is dependent on inclusion shape and its composition profile cooperatively and that the plastic behavior of each layer should be taken into account in optimum design of a ceramic-metal FGM.

  13. Viscoelastic behavior of rubbery materials

    CERN Document Server

    Roland, C M

    2011-01-01

    The gigantic size of polymer molecules makes them viscoelastic - their behavior changes depending on how fast and for how long the material is used. This book looks at the latest discoveries in the field from a fundamental molecular perspective, in order to guide the development of better and new applications for soft materials.

  14. A numerical model for the thermo-elasto-plastic behaviour of a material

    Science.gov (United States)

    Ray, Sujit K.; Utki, Senol

    1989-01-01

    This paper presents a numerical model for the thermo-elasto-plastic behavior of an isotropic material. The model is based on the assumption that the yielding of the material obeys von Mises distortion energy theory and the material exhibits isotropic strain hardening. This unique model can be used both for isothermal and non-isothermal cases. The original formulation for the non-isothermal three-dimensional case has been specialized for plane stress conditions and the equations for the computation of warping and thickness change are provided. The finite element implementation of this model is also outlined.

  15. Plastic packaging materials and environmental problems. Plastic hosozai to kankyo mondai

    Energy Technology Data Exchange (ETDEWEB)

    Uemura, T. (Sekisui Plastics Co. Ltd., Osaka (Japan))

    1992-05-01

    This paper describes the recent trends in the environmental problems created from used plastic packaging materials. The 23 wards of the city of Tokyo produce refuses daily of 12,000 tons (1990), with plastics accounting for 15% by volume. Discussions to deal with plastic refuses that are bulky and standing out began as early as in 1971 when the disposal study meeting was inaugurated. As a result, wastes from polyvinyl chloride sheet for agricultural green houses had 40% recovered and recycled out of 100,000 tons generated annually, and styrofoam wastes at 10% of 150,000 tons. The wastes disposal law and the recycling law were established in 1991 aiming at reducing volume of wastes, promoting re-utilization, and assuring appropriate disposal methods and facilities. The Wastes Re-utilization Association was organized to handle styrofoam wastes that are attracting strong attention recently, the association having begun its activities with a good start. It is expected that styrofoam wastes will be molten thermally and regenerated into the same styrofoam products. Styrofoam could be more energy saving and resource saving material than paper cups. 6 refs., 10 figs., 5 tabs.

  16. Training-induced behavioral and brain plasticity in inhibitory control

    OpenAIRE

    Lucas eSpierer; Camille eChavan; Aurelie Lynn Manuel

    2013-01-01

    Deficits in inhibitory control, the ability to suppress ongoing or planned motor or cognitive processes, contribute to many psychiatric and neurological disorders. The rehabilitation of inhibition-related disorders may therefore benefit from neuroplasticity-based training protocols aiming at normalizing inhibitory control proficiency and the underlying brain networks. Current literature on training-induced behavioral and brain plasticity in inhibitory control suggests that improvements may fo...

  17. Continuum mechanical and computational aspects of material behavior

    Energy Technology Data Exchange (ETDEWEB)

    Fried, Eliot; Gurtin, Morton E.

    2000-02-10

    The focus of the work is the application of continuum mechanics to materials science, specifically to the macroscopic characterization of material behavior at small length scales. The long-term goals are a continuum-mechanical framework for the study of materials that provides a basis for general theories and leads to boundary-value problems of physical relevance, and computational methods appropriate to these problems supplemented by physically meaningful regularizations to aid in their solution. Specific studies include the following: the development of a theory of polycrystalline plasticity that incorporates free energy associated with lattice mismatch between grains; the development of a theory of geometrically necessary dislocations within the context of finite-strain plasticity; the development of a gradient theory for single-crystal plasticity with geometrically necessary dislocations; simulations of dynamical fracture using a theory that allows for the kinking and branching of cracks; computation of segregation and compaction in flowing granular materials.

  18. Pyrolysis of plastic packaging waste: A comparison of plastic residuals from material recovery facilities with simulated plastic waste.

    Science.gov (United States)

    Adrados, A; de Marco, I; Caballero, B M; López, A; Laresgoiti, M F; Torres, A

    2012-05-01

    Pyrolysis may be an alternative for the reclamation of rejected streams of waste from sorting plants where packing and packaging plastic waste is separated and classified. These rejected streams consist of many different materials (e.g., polyethylene (PE), polypropylene (PP), polystyrene (PS), polyvinyl chloride (PVC), polyethylene terephthalate (PET), acrylonitrile butadiene styrene (ABS), aluminum, tetra-brik, and film) for which an attempt at complete separation is not technically possible or economically viable, and they are typically sent to landfills or incinerators. For this study, a simulated plastic mixture and a real waste sample from a sorting plant were pyrolyzed using a non-stirred semi-batch reactor. Red mud, a byproduct of the aluminum industry, was used as a catalyst. Despite the fact that the samples had a similar volume of material, there were noteworthy differences in the pyrolysis yields. The real waste sample resulted, after pyrolysis, in higher gas and solid yields and consequently produced less liquid. There were also significant differences noted in the compositions of the compared pyrolysis products.

  19. The relation between severe plastic deformation microstructure and corrosion behavior of AZ31 magnesium alloy

    Energy Technology Data Exchange (ETDEWEB)

    Ben Hamu, G. [Department of Materials Engineering, Ben-Gurion University of the Negev, Beer-Sheva 84105 (Israel); Eliezer, D. [Department of Materials Engineering, Ben-Gurion University of the Negev, Beer-Sheva 84105 (Israel); Institute of Materials Science and Engineering, TU Clausthal (Germany)], E-mail: deliezer@bgu.ac.il; Wagner, L. [Institute of Materials Science and Engineering, TU Clausthal (Germany)

    2009-01-22

    The quest for ever, higher performance in structural applications has resulted in the outgoing development of new or improved materials with novel crystallographic textures, microstructures, and compositions. However, commercial applicability of such materials depends heavily on the development of economical and robust manufacturing methods. Due to the promise of excellent properties, such as superplasticity, high strength, good ductility, enhanced high cycle fatigue life, and good corrosion resistance, interest has grown in nanostructure bulk materials. Those materials are defined most often as materials exhibiting nanocrystalline grain structures and particle sizes below 100 nm in at least one dimension. In recent years, bulk nanostructure materials processed by methods of severe plastic deformation (SPD) such as equal channel angular extrusion (ECAE) have attracted the growing interest of specialists in materials science. The main object of this research is to compare the microstructural changing and corrosion behavior of magnesium alloy AZ31 after extrusion and severe plastic deformation by ECAE process. The ECAE process can produce intense and uniform deformation by simple shear and provides a convenient procedure for introducing an ultra fine grain size into a material. The samples were prepared by using hot extrusion methods. Hardness and AC and DC polarization tests were carried out on the extruded rods, and the microstructure was examined using optical, electron microscopy (SEM, TEM) and EDS. The results showed that the severe plastic deformation process affected both the microstructure and the corrosion behavior of AZ31 Mg alloy. These results can be explained by the effects of the process on microstructure of AZ31 Mg alloy such as grain size and dislocation density caused by the change in recrystallization behavior.

  20. Viscous-elastic-plastic behavior of bone using Berkovich nanoindentation

    Science.gov (United States)

    Olesiak, Sara E.; Oyen, Michelle L.; Ferguson, Virginia L.

    2010-05-01

    A series viscous-elastic-plastic (VEP) indentation model was expanded to include analysis of the common trapezoidal testing condition, consisting of constant loading—and unloading—rates with an intervening creep hold period. This full VEP model was applied to analyze nanoindentation test of three polymers and five different types of bone. The full VEP solution allows for direct determination of the viscous term as calculated from the creep hold, while the elastic and plastic material parameters were determined from a non-linear curve-fit of the unloading displacement-time data. Additionally, the use of the trapezoidal loading procedure permitted analysis of the unloading load-displacement data with traditional Oliver-Pharr analysis; the material properties from this analysis compared well with those obtained with VEP analysis. Using the full VEP solution and fitted material constants the loading and creep hold displacement-time curves were simulated and matched well to both polymer and bone experimental data. The full VEP solution shows great promise in for obtaining material parameters for many viscoelastic materials such as hydrated bone, polymers, and other biological tissues.

  1. Extraction of stearate salts from plastic materials used in pharmaceutical applications.

    Science.gov (United States)

    Jenke, Dennis

    2010-01-01

    Plastic materials are widely used in medical items such as solution containers, infusion sets, transfer tubing, devices, processing equipment and systems, filters, and the like. Components in medical items can leach out of such items when they are contacted by a therapeutic product or product-related solution. Stearic acid and stearate salts are commonly present in medical and food packaging, either as plastic additives, processing aids, or contaminants, and their leaching from plastics is well documented. With a pK(a) in the range of 5.1 to 5.6 and limited aqueous solubility (log P(o/w) greater than 8), the leaching of stearic acid (and its related metal salts) into pharmaceutical products is expected to be strongly dependent on the product's pH and polarity. In order to establish and understand the leaching behavior of stearate-containing materials, three compounds (stearic acid, calcium stearate, and zinc stearate) and four polymeric materials containing these compounds were contacted with aqueous buffers in the pH range of 2.5 to 11. The leached levels of calcium, zinc, stearate, palmitate, and total organic carbon (TOC) were measured in the resulting solutions and are reported. For materials containing only stearic acid or salts themselves, the extraction of these entities is pH-dependent. At low pH, the cation counter-ions of the stearate salts are extracted from the plastic materials by a process that can loosely be termed ion exchange. At intermediate pH, little or no extraction of the stearates occurs. At high pH, the stearates are extracted from the materials to a very limited extent due to the solubility of the acid and/or salts in the extraction medium.

  2. Experimental Study on Elastic-Plastic Behavior of SRC Columns with High Strength Steel

    OpenAIRE

    2006-01-01

    The demand to use high strength and high performance material because of large span and high rise of building in recent years. As to use of high-strength steel in composite steel and reinforced concrete structures, it remains to be clarified whether the ductile behavior can be ensured, especially when the high-strength steel is used in combination with High-strength concrete. This paper describes the test results on the elasto-plastic behavior of SRC column using high strength steel, and disc...

  3. Formulation and computational aspects of plasticity and damage models with application to quasi-brittle materials

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Z.; Schreyer, H.L. [New Mexico Engineering Research Institute, Albuquerque, NM (United States)

    1995-09-01

    The response of underground structures and transportation facilities under various external loadings and environments is critical for human safety as well as environmental protection. Since quasi-brittle materials such as concrete and rock are commonly used for underground construction, the constitutive modeling of these engineering materials, including post-limit behaviors, is one of the most important aspects in safety assessment. From experimental, theoretical, and computational points of view, this report considers the constitutive modeling of quasi-brittle materials in general and concentrates on concrete in particular. Based on the internal variable theory of thermodynamics, the general formulations of plasticity and damage models are given to simulate two distinct modes of microstructural changes, inelastic flow and degradation of material strength and stiffness, that identify the phenomenological nonlinear behaviors of quasi-brittle materials. The computational aspects of plasticity and damage models are explored with respect to their effects on structural analyses. Specific constitutive models are then developed in a systematic manner according to the degree of completeness. A comprehensive literature survey is made to provide the up-to-date information on prediction of structural failures, which can serve as a reference for future research.

  4. Interactions between six psychotherapeutic drugs and plastic containers. Influence of plastic material and infusion solutions.

    Science.gov (United States)

    Airaudo, C B; Gayte-Sorbier, A; Bianchi, C; Verdier, M

    1993-06-01

    The interactions of chlorpromazine, clomipramine, maprotiline and viloxazine hydrochlorides, and of clorazepate dipotassium salt and diazepam with polyvinyl chloride (PVC) and Stedim 6 infusion bags were studied. Stedim 6, is anew multilayer film whose inner layer is made of polyethylene. The drugs were in 5% dextrose and 0.9% sodium chloride isotonic solutions and the influence of these was also considered. The remaining concentrations of each drug were determined at regular time intervals in a 24-h period, by a spectrofluorometric method for chlorpromazine hydrochloride and by ultraviolet spectrophotometric methods for the other drugs. No binding was observed for viloxazine and maprotiline hydrochlorides whatever the infusion solution and the plastic container. A slight retention in PVC bags, but not in Stedim 6 ones, was noted for clomipramine hydrochloride and clorazepate dipotassium salt. This was more marked in the sodium chloride solution than in the dextrose one. Diazepam and chlorpromazine hydrochloride were bound both in PVC and Stedim 6 bags, but more in the former and more again in the sodium chloride solution than in the dextrose one. The results were explained in terms of the degree of crystallinity of the plastic material and the degree of lipophilicity of the drugs. Practical consequences are discussed.

  5. On Aerobic Exercise and Behavioral and Neural Plasticity

    Directory of Open Access Journals (Sweden)

    Caitlin Peplinski

    2012-11-01

    Full Text Available Aerobic exercise promotes rapid and profound alterations in the brain. Depending upon the pattern and duration of exercise, these changes in the brain may extend beyond traditional motor areas to regions and structures normally linked to learning, cognition, and emotion. Exercise-induced alterations may include changes in blood flow, hormone and growth factor release, receptor expression, angiogenesis, apoptosis, neurogenesis, and synaptogenesis. Together, we believe that these changes underlie elevations of mood and prompt the heightened behavioral plasticity commonly observed following adoption of a chronic exercise regimen. In the following paper, we will explore both the psychological and psychobiological literatures relating to exercise effects on brain in both human and non-human animals and will attempt to link plastic changes in these neural structures to modifications in learned behavior and emotional expression. In addition, we will explore the therapeutic potential of exercise given recent reports that aerobic exercise may serve as a neuroprotectant and can also slow cognitive decline during normal and pathological aging.

  6. Elastic-plastic characterization of a cast stainless steep pipe elbow material

    Energy Technology Data Exchange (ETDEWEB)

    Joyce, J.A. [Naval Academy, Annapolis, MD (United States); Hackett, E.M.; Roe, C. [David W. Taylor Naval Ship Research and Development Center, Annapolis, MD (United States)

    1992-01-01

    Tests conducted in Japan as part of the High Level Vibration Test (HLVT) program for reactor piping systems revealed fatigue crack growth in a cast stainless steel pipe elbow. The material tested was equivalent to ASME SA-351CF8M. The David Taylor Research Center (DTRC) was tasked to developed the appropriate material property data to characterize cyclic deformation, cyclic elastic-plastic crack growth and ductile tearing resistance in the pipe elbow material. It was found that the cast stainless steel was very resistant to ductile crack extension. J-R curves essentially followed a blunting behavior to very high J levels. Low cycle fatigue crack growth rate data obtained on this material using a cyclic J integral approach was consistent with the high cycle fatigue crack growth rate and with a standard textbook correlation equation typical for this type of material. Evaluation of crack closure effects was essential to accurately determine the crack driving force for cyclic elastic- plastic crack growth in this material. SEM examination of several of the cyclic J test fracture surfaces indicated that fatigue was the primary mode of fracture with ductile crack extension intervening only during the last few cycles of loading.

  7. Determining biodegradability of plastic materials under controlled and natural composting environments.

    Science.gov (United States)

    Mohee, R; Unmar, G

    2007-01-01

    With the advent of recently promulgated Government regulations on plastics in Mauritius, a study was initiated to examine the biodegradability of two different types of plastic, namely Willow Ridge Plastics - PDQ-H additive (Plastic A) and Ecosafe Plastic - TDPA additive (Plastic B) under controlled and natural composting environments. The results obtained from the controlled composting environment showed that the cumulative carbon dioxide evolution for Plastic A was much higher than that for Plastic B. Plastic A therefore showed a higher level of biodegradation in terms of CO2 evolution than Plastic B. However, from the regression analysis, it was found that the level of CO2 varying with time fitted the sigmoid type curves with very high correlation coefficients (R2 values: 0.9928, 0.9921 and 0.9816, for reference material, inoculum and Plastic A, respectively). The corresponding F-values obtained from the ANOVA analysis together with significance levels of pbiodegradability experiment were significant. The other experiment was undertaken to observe any physical change of Plastics A and B as compared to a reference plastic, namely, compostable plastic bag (Mater-Bi product-Plastic C), when exposed to a natural composting environment. Thermophilic temperatures were obtained for about 3-5 days of composting and the moisture content was in the range of 60-80% throughout the degradation process. It was observed that after 55 days of composting, Plastic C degraded completely while Plastic A and Plastic B did not undergo any significant degradation. It can be concluded that naturally based plastic made of starch would degrade completely in a time frame of 60 days, whereas plastics with biodegradable additive would require a longer time.

  8. The Cyclic Deformation Behavior of Severe Plastic Deformation (SPD Metals and the Influential Factors

    Directory of Open Access Journals (Sweden)

    Charles C. F. Kwan

    2012-02-01

    Full Text Available A deeper understanding of the mechanical behavior of ultra-fine (UF and nanocrystalline (NC grained metals is necessary with the growing interest in using UF and NC grained metals for structural applications. The cyclic deformation response and behavior of UF and NC grained metals is one aspect that has been gaining momentum as a major research topic for the past ten years. Severe Plastic Deformation (SPD materials are often in the spotlight for cyclic deformation studies as they are usually in the form of bulk work pieces and have UF and NC grains. Some well known techniques in the category of SPD processing are High Pressure Torsion (HPT, Equal Channel Angular Pressing (ECAP, and Accumulative Roll-Bonding (ARB. In this report, the literature on the cyclic deformation response and behavior of SPDed metals will be reviewed. The cyclic response of such materials is found to range from cyclic hardening to cyclic softening depending on various factors. Specifically, for SPDed UF grained metals, their behavior has often been associated with the observation of grain coarsening during cycling. Consequently, the many factors that affect the cyclic deformation response of SPDed metals can be summarized into three major aspects: (1 the microstructure stability; (2 the limitation of the cyclic lifespan; and lastly (3 the imposed plastic strain amplitude.

  9. Yield Functions and Plastic Potentials for BCC Metals and Possibly Other Materials

    Energy Technology Data Exchange (ETDEWEB)

    Christensen, R M

    2005-09-29

    Yield functions and plastic potentials are expressed in terms of the invariants of the stress tensor for polycrystalline metals and other isotropic materials. The plastic volume change data of Richmond is used to evaluate the embedded materials properties for some bcc metals and one polymer. A general form for the plastic potential is found that is intended to represent and cover a wide range of materials types.

  10. Composite Behavior of Lath Martensite Steels Induced by Plastic Strain, a New Paradigm for the Elastic-Plastic Response of Martensitic Steels

    Science.gov (United States)

    Ungár, Tamás; Harjo, Stefanus; Kawasaki, Takuro; Tomota, Yo; Ribárik, Gábor; Shi, Zengmin

    2017-01-01

    Based on high-resolution neutron diffraction experiments, we will show that in lath martensite steels, the initially homogeneous dislocation structure, i.e., homogeneous on the length scale of grain size, is disrupted by plastic deformation, which, in turn, produces a composite on the length scale of martensite lath packets. The diffraction patterns of plastically strained martensitic steel reveal characteristically asymmetric peak profiles in the same way as has been observed in materials with heterogeneous dislocation structures. The quasi homogeneous lath structure, formed by quenching, is disrupted by plastic deformation producing a composite structure. Lath packets oriented favorably or unfavorably for dislocation glide become soft or hard. Two lath packet types develop by work softening or work hardening in which the dislocation densities become smaller or larger compared to the initial average dislocation density. The decomposition into soft and hard lath packets is accompanied by load redistribution and the formation of long-range internal stresses between the two lath packet types. The composite behavior of plastically deformed lath martensite opens a new way to understand the elastic-plastic response in this class of materials.

  11. Behavioral Response to Plastic Bag Legislation in Botswana

    OpenAIRE

    2010-01-01

    This paper investigates the use of charges and standards in dealing with a common externality, plastic litter from shopping bags in Botswana. The country passed a plastic bag tax (effective 2007) to curb the plastic bag demand. Interestingly, the legislation did not force retailers to charge for plastic bags, which they did voluntarily at different prices. We assessed the environmental effectiveness and efficiency of the plastic bag legislation by analyzing consumers’ sensitivity to the impro...

  12. Modeling high temperature materials behavior for structural analysis

    CERN Document Server

    Naumenko, Konstantin

    2016-01-01

    This monograph presents approaches to characterize inelastic behavior of materials and structures at high temperature. Starting from experimental observations, it discusses basic features of inelastic phenomena including creep, plasticity, relaxation, low cycle and thermal fatigue. The authors formulate constitutive equations to describe the inelastic response for the given states of stress and microstructure. They introduce evolution equations to capture hardening, recovery, softening, ageing and damage processes. Principles of continuum mechanics and thermodynamics are presented to provide a framework for the modeling materials behavior with the aim of structural analysis of high-temperature engineering components.

  13. ASSESSMENT OF PLASTIC FLOWS AND STOCKS IN SERBIA USING MATERIAL FLOW ANALYSIS

    Directory of Open Access Journals (Sweden)

    Goran Vujić

    2010-01-01

    Full Text Available Material flow analysis (MFA was used to assess the amounts of plastic materials flows and stocks that are annually produced, consumed, imported, exported, collected, recycled, and disposed in the landfills in Serbia. The analysis revealed that approximatelly 269,000 tons of plastic materials are directly disposed in uncontrolled landfills in Serbia without any preatretment, and that siginificant amounts of these materials have already accumulated in the landfills. The substantial amounts of landfilled plastics represent not only a loss of valuable recourses, but also pose a seriuos treath to the environment and human health, and if the trend of direct plastic landfilling is continued, Serbia will face with grave consecequnces.

  14. Excised Abdominoplasty Material as a Systematic Plastic Surgical Training Model

    Directory of Open Access Journals (Sweden)

    M. Erol Demirseren

    2012-01-01

    Full Text Available Achieving a level of technical skill and confidence in surgical operations is the main goal of plastic surgical training. Operating rooms were accepted as the practical teaching venues of the traditional apprenticeship model. However, increased patient population, time, and ethical and legal considerations made preoperation room practical work a must for plastic surgical training. There are several plastic surgical teaching models and simulators which are very useful in preoperation room practical training and the evaluation of plastic surgery residents. The full thickness skin with its vascular network excised in abdominoplasty procedures is an easily obtainable real human tissue which could be used as a training model in plastic surgery.

  15. The industrial metabolism of plastics : analysis of material flows, energy consumption and CO2 emissions in the lifecycle of plastics

    NARCIS (Netherlands)

    Joosten, Ludovicus Antonius Josephus

    2001-01-01

    This thesis deals with the question: Which are promising options for decreasing material consumption, energy consumption and CO2 emissions in the lifecycle of plastics? The research described in this thesis mainly focuses on measures that change the material system, i.e. measures that change the

  16. The industrial metabolism of plastics : analysis of material flows, energy consumption and CO2 emissions in the lifecycle of plastics

    NARCIS (Netherlands)

    Joosten, Ludovicus Antonius Josephus

    2002-01-01

    This thesis deals with the question: Which are promising options for decreasing material consumption, energy consumption and CO2 emissions in the lifecycle of plastics? The research described in this thesis mainly focuses on measures that change the material system, i.e. measures that change the pat

  17. Finite Element Modeling to Simulate the Elasto-Plastic Behavior of Polycrystalline in 718

    Science.gov (United States)

    Bonifaz, E. A.

    2013-01-01

    A 3D strain gradient plasticity finite element model was developed to simulate the elasto-plastic behavior of polycrystalline IN 718 alloys. The proposed model constructed in the basis of the so-called Kocks-Mecking model is used to determine the influence of microstructure attributes on the inelastic stress-strain distribution. Representative Volume Elements (RVEs) of different edge size but similar grain morphology and affordable computational meshes were tested to investigate the link between micro and macro variables of deformation and stress. The virtual specimens subjected to continuous monotonic straining loading conditions were constrained with random periodic boundary conditions. The difference in crystallographic orientation (which evolves in the process of straining) and the incompatibility of deformation between neighboring grains were accounted by the introduction of averaged Taylor factors and the evolution of geometrically necessary dislocation density. The effect of plastic deformation gradients imposed by the microstructure is clearly observed. Results demonstrate a strong dependence of flow stress and plastic strain on phase type and grain size. A main strategy for constitutive modeling of individual bulk grains is presented. The influence of the grain size on the aggregate response, in terms of local stress variations and aggregate elastic moduli was analyzed. It was observed that the elastic modulus in the bulk material is not dependent on grain size.

  18. Behavioral plasticity through the modulation of switch neurons.

    Science.gov (United States)

    Vassiliades, Vassilis; Christodoulou, Chris

    2016-02-01

    A central question in artificial intelligence is how to design agents capable of switching between different behaviors in response to environmental changes. Taking inspiration from neuroscience, we address this problem by utilizing artificial neural networks (NNs) as agent controllers, and mechanisms such as neuromodulation and synaptic gating. The novel aspect of this work is the introduction of a type of artificial neuron we call "switch neuron". A switch neuron regulates the flow of information in NNs by selectively gating all but one of its incoming synaptic connections, effectively allowing only one signal to propagate forward. The allowed connection is determined by the switch neuron's level of modulatory activation which is affected by modulatory signals, such as signals that encode some information about the reward received by the agent. An important aspect of the switch neuron is that it can be used in appropriate "switch modules" in order to modulate other switch neurons. As we show, the introduction of the switch modules enables the creation of sequences of gating events. This is achieved through the design of a modulatory pathway capable of exploring in a principled manner all permutations of the connections arriving on the switch neurons. We test the model by presenting appropriate architectures in nonstationary binary association problems and T-maze tasks. The results show that for all tasks, the switch neuron architectures generate optimal adaptive behaviors, providing evidence that the switch neuron model could be a valuable tool in simulations where behavioral plasticity is required.

  19. Classification of plastic materials by imaging laser-induced ablation plumes

    Science.gov (United States)

    Negre, Erwan; Motto-Ros, Vincent; Pelascini, Frederic; Yu, Jin

    2016-08-01

    A method of rapid classification and identification of plastic materials has been studied in this work. Such method is based on fast spectroscopic imagery of laser-induced ablation plume on plastics to be analyzed. More specifically, a classification schema has been developed first according to the nature of the CC bonds which characterize the polymer matrix. Our results show that the spatial distribution and the evolution of the molecular species in the ablation plume, such as C2 and CN, exhibit clear different behaviors for polymers without any native CC bond, with CC single bonds or with CC double bonds respectively. Therefore the morphological parameters of the populations of the molecular species extracted from the time-resolved spectroscopic images of the plumes provide efficient indicators to classify the polymers characterized by the above mentioned different kinds of CC bonds. When dealing with different polymers with the same kind of CC bond, CC single bond for instance, other indicators should be introduced to provide the further discrimination. Such indicators can be for example a specific native molecular bond other than CC bonds, CN for example, the total emission intensity of which may exhibit specific time evolution. The robustness of the developed classification schema has been then studied with respect to two of the most frequently used additives in plastics fabrication, graphite and titanium. Our results show a negligible influence of these additives in the morphology of the populations of the molecular species when such additives are mixed into the polymer matrix with the percentages usually used in plastics productions, which demonstrates the validity of the developed classification schema for plastics.

  20. Marine fungi: Degraders of poly-3-hydroxyalkanoate based plastic materials

    Directory of Open Access Journals (Sweden)

    Matavulj Milan

    2009-01-01

    Full Text Available The search for new biosynthetic and biodegradable materials to save nonrenewable resources and reduce global pollution problems is an urgent task. Recently, materials like thermoplastic poly-3-hydroxyalkanoates (PHA, have been found synthesized by bacteria as storage materials. The major PHAs synthesized are poly-b-hydroxybutyrate (PHB, poly-b-hydroxyvalerate (PHV and their copolymers. They are already commercially produced and used as BIOPOLTM (ICI, England. Their complete degradability by bacteria has already been shown. Today, oceans and estuaries serve as major landfills, and since fungi are an important part of the degrading microbiota, in order to prove their participation in the degradation process, a simple degradation test suitable for fungi and marine conditions had to be developed. Several solid media based on artificial sea water, differing in the content of non-alkanoate organics and supplemented with 0.1% PHA (or BIOPOLTM as a main source of carbon have been tested. The testing principle consists of clearing the turbid medium in test tube or plates caused by suspended granules of PHA. All media tested supported the growth of fungi. For the discrete and transparent clearing of zones, a mineral medium with 0.01% peptone, 0.01% yeast extract, and 0.1% PHB or BIOPOLTM was finally chosen where the fine and evenly distributed turbidity is accomplished by a specific procedure. This method allows the investigation of degradability of PHA-based plastic materials as well as screening for fungal ability to depolymerise pure PHA homopolymers. Using this medium, 32 strains of marine yeasts and 102 strains of marine mycelial fungi belonging to different systematic and ecological groups were tested for their ability to degrade PHAs. Only about 4% of the strains were able to degrade BIOPOLTM and about 6% depolymerised pure PHB homopolymer. This is in sharp contrast to the results of our previous experiments with 143 strains of terrestrial fungi

  1. Study on Plastic Coated Overburnt Brick Aggregate as an Alternative Material for Bituminous Road Construction

    OpenAIRE

    Dipankar Sarkar; Manish Pal; Sarkar, Ashoke K.

    2016-01-01

    There are different places in India where natural stone aggregates are not available for constructional work. Plastic coated OBBA can solve the problem of shortage of stone aggregate to some extent. The engineers are always encouraged to use locally available materials. The present investigation is carried out to evaluate the plastic coated OBBA as an alternative material for bituminous road construction. Shredded waste plastics are mixed with OBBA in different percentages as 0.38, 0.42, 0.46...

  2. New absorbent acoustic materials from plastic bottle remnants

    Directory of Open Access Journals (Sweden)

    del Rey, R.

    2011-12-01

    Full Text Available In the building acoustics field usually fibrous materials are used as sound absorbing materials. Nowadays polyester fiber is one of the most used but the pure chip of polyester has a problem. Polyester is obtained of petroleum and its price was increasing last years. This paper, presents an alternative polyester wool which obtained by PET treatment (recycle of plastic bottle’s. Absorption coefficient values at normal incidence measured in reverberation chamber were compared (new wool obtained by PET method and materials obtained from pure chip of polyester.Furthermore, this paper propound a empiric model that describe the acoustic performance of this new wool. The results have been good. The pure fiber has been replaced by recycle fiber in its manufacture process.

    En el ámbito de acústica de la edificación es común el uso de materiales fibrosos como materiales absorbentes acústicos. Uno de estos materiales cada vez más utilizado es la lana de poliéster. Un problema que presenta el chip virgen de poliéster es que se obtiene del petróleo, cuyo precio no hace más que incrementarse en los últimos años. En este trabajo se presenta una lana de poliéster alternativa, obtenida mediante el tratamiento del PET, a través del conveniente ciclo de reciclado de botellas de plástico. Se comparan valores del coeficiente de absorción; en incidencia normal y en cámara reverberante de los materiales elaborados a partir de chip virgen y de las nuevas lanas obtenidas del PET. Además, se propone un modelo empírico de comportamiento acústico de estas nuevas lanas. Los resultados obtenidos han sido favorables, la fibra virgen ya ha sido sustituida por fibra reciclada en su proceso de fabricación.

  3. Effect of Changing Table Tennis Ball Material from Celluloid to Plastic on the Post-Collision Ball Trajectory

    Directory of Open Access Journals (Sweden)

    Inaba Yuki

    2017-01-01

    Full Text Available The official material used in table tennis balls was changed from celluloid to plastic, a material free of celluloid, in 2014. The purpose of this study was to understand the differences and similarities in the two types of ball materials by comparing their behavior upon collision with a table. The behavior of the balls before and after collision with a table, at various initial speeds ranging from 15 to 115 km/h, was captured using high-speed cameras. Velocities and spin rates before collision and velocities after collision were computed to calculate the coefficients of restitution and friction. Based on the computed variables, the post-collision trajectories of both balls were calculated by integrating the equation of motion of the ball for simulated service, smash and drive conditions with respect to time. The coefficients of restitution were higher for the plastic balls than the celluloid ones when the initial vertical velocities were higher. The coefficients of friction were higher for plastic balls when the initial horizontal contact point velocities were slower. Because of the differences in the material characteristics, the plastic ball trajectories of services with backspin and drives with great topspin were expected to be different from those of celluloid balls. Since the extent of differences between the two ball types varied depending on the initial conditions, testing at various initial conditions was suggested for comparing and understanding the characteristics of the balls.

  4. An exploration of plastic deformation dependence of cell viability and adhesion in metallic implant materials.

    Science.gov (United States)

    Uzer, B; Toker, S M; Cingoz, A; Bagci-Onder, T; Gerstein, G; Maier, H J; Canadinc, D

    2016-07-01

    The relationship between cell viability and adhesion behavior, and micro-deformation mechanisms was investigated on austenitic 316L stainless steel samples, which were subjected to different amounts of plastic strains (5%, 15%, 25%, 35% and 60%) to promote a variety in the slip and twin activities in the microstructure. Confocal laser scanning microscopy (CLSM) and field emission scanning electron microscopy (FESEM) revealed that cells most favored the samples with the largest plastic deformation, such that they spread more and formed significant filopodial extensions. Specifically, brain tumor cells seeded on the 35% deformed samples exhibited the best adhesion performance, where a significant slip activity was prevalent, accompanied by considerable slip-twin interactions. Furthermore, maximum viability was exhibited by the cells seeded on the 60% deformed samples, which were particularly designed in a specific geometry that could endure greater strain values. Overall, the current findings open a new venue for the production of metallic implants with enhanced biocompatibility, such that the adhesion and viability of the cells surrounding an implant can be optimized by tailoring the surface relief of the material, which is dictated by the micro-deformation mechanism activities facilitated by plastic deformation imposed by machining.

  5. Crystallinity in starch plastics: consequences for material properties

    NARCIS (Netherlands)

    Vliegenthart, J.F.G.; Soest, J.J.G. van

    1997-01-01

    The processing of starches with biodegradable additives has made biodegradable plastics suitable for a number of applications. Starch plastics are partially crystalline as a result of residual crystallinity and the recrystallization of amylose and amylopectin. Such crystallinity is a key determinant

  6. The Portuguese plastic carrier bag tax: The effects on consumers' behavior.

    Science.gov (United States)

    Martinho, Graça; Balaia, Natacha; Pires, Ana

    2017-03-01

    Marine litter from lightweight plastic bags is a global problem that must be solved. A plastic bag tax was implemented in February 2015 to reduce the consumption of plastic grocery bags in Portugal and in turn reduce the potential contribution to marine litter. This study analyzes the effect of the plastic bag tax on consumer behavior to learn how it was received and determine the perceived effectiveness of the tax 4months after its implementation. In addition, the study assessed how proximity to coastal areas could influence behaviors and opinions. The results showed a 74% reduction of plastic bag consumption with a simultaneously 61% increase of reusable plastic bags after the tax was implemented. Because plastic bags were then reused for shopping instead of garbage bags, however, the consumption of garbage bags increased by 12%. Although reduction was achieved, the tax had no effect on the perception of marine litter or the impact of plastic bags on environment and health. The majority of respondents agree with the tax but view it as an extra revenue to the State. The distance to the coast had no meaningful influence on consumer behavior or on the perception of the tax. Although the tax was able to promote the reduction of plastics, the role of hypermarkets and supermarkets in providing alternatives through the distribution of reusable plastic bags was determinant to ensuring the reduction.

  7. Training-induced behavioral and brain plasticity in inhibitory control

    Directory of Open Access Journals (Sweden)

    Lucas eSpierer

    2013-08-01

    Full Text Available Deficits in inhibitory control, the ability to suppress ongoing or planned motor or cognitive processes, contribute to many psychiatric and neurological disorders. The rehabilitation of inhibition-related disorders may therefore benefit from neuroplasticity-based training protocols aiming at normalizing inhibitory control proficiency and the underlying brain networks. Current literature on training-induced behavioral and brain plasticity in inhibitory control suggests that improvements may follow either from the development of automatic forms of inhibition or from the strengthening of top-down, controlled inhibition. Automatic inhibition develops in conditions of consistent and repeated associations between inhibition-triggering stimuli and stopping goals. Once established, the stop signals directly elicit inhibition, thereby bypassing slow, top-down executive control and accelerating stopping processes. In contrast, training regimens involving varying stimulus-response associations or frequent inhibition failures prevent the development of automatic inhibition and thus strengthen top-down inhibitory processes rather than bottom-up ones. We discuss these findings in terms of developing optimal inhibitory control training regimens for rehabilitation purposes.

  8. Material length scales in gradient-dependent plasticity/damage and size effects: Theory and computation

    Science.gov (United States)

    Abu Al-Rub, Rashid Kamel

    Structural materials display a strong size-dependence when deformed non-uniformly into the inelastic range: smaller is stronger. This effect has important implications for an increasing number of applications in structural failure, electronics, functional coatings, composites, micro-electro-mechanical systems (MEMS), nanostructured materials, micro/nanometer fabrication technologies, etc. The mechanical behavior of these applications cannot be characterized by classical (local) continuum theories because they incorporate no, 'material length scales' and consequently predict no size effects. On the other hand, it is still not possible to perform quantum and atomistic simulations on realistic time and structures. It is therefore necessary to develop a scale-dependent continuum theory bridging the gap between the classical continuum theories and the atomistic simulations in order to be able to design the size-dependent structures of modern technology. Nonlocal rate-dependent and gradient-dependent theories of plasticity and damage are developed in this work for this purpose. We adopt a multi-scale, hierarchical thermodynamic consistent framework to construct the material constitutive relations for the scale-dependent plasticity/damage behavior. Material length scales are implicitly and explicitly introduced into the governing equations through material rate-dependency (viscosity) and coefficients of spatial higher-order gradients of one or more material state variables, respectively. The proposed framework is implemented into the commercially well-known finite element software ABAQUS. The finite element simulations of material instability problems converge to meaningful results upon further refinement of the finite element mesh, since the width of the fracture process zone (shear band) is determined by the intrinsic material length scale; while the classical continuum theories fail to address this problem. It is also shown that the proposed theory is successful for

  9. Characteristics of materials and thermal treatments applied to gearwheels obtained by plastic deformation

    Science.gov (United States)

    Bostan, I.; Dulgheru, V.; Trifan, N.

    2016-08-01

    A variety of materials are used in the manufacture of gearwheels. These materials satisfy various working conditions for gears. Such gears are made of metallic materials - ferrous, non-ferrous and from plastic materials. Among ferrous materials the following are used: irons; cast, forged and rolled steels; among non-ferrous materials the following are used: bronze, aluminium alloys, brass, etc., and of plastics the following are used: textolite, polyamide, polyacetal. In the practice of exploitation and in the process of special research it was established that the permissible load, according to teeth contact resistance, is generally determined by the hardness of the material. The highest hardness and respectively, the smallest sizes and reduced mass of the transmission can be obtained in the manufacture of steel gears via thermal treatment. It is obvious that by plastic deformation at cold it cannot be obtained gearwheels with complicated configuration as deformed plastic metal will form cracks caused by low plasticity. To improve processability by plastic deformation the mouldings for gearwheels are heated. With increasing the heating temperature, plasticity increases and resistance to deformation decreases.

  10. 75 FR 16514 - Bayer Material Science, LLC, Formally Known as Sheffield Plastics, Including On-Site Leased...

    Science.gov (United States)

    2010-04-01

    ... Employment and Training Administration Bayer Material Science, LLC, Formally Known as Sheffield Plastics... Material Science, LLC, formally known as Sheffield Plastics, including on-site leased workers from... that Bayer Material Science, LLC was formally known as Sheffield Plastics. Some workers separated...

  11. Study on Plastic Coated Overburnt Brick Aggregate as an Alternative Material for Bituminous Road Construction

    Directory of Open Access Journals (Sweden)

    Dipankar Sarkar

    2016-01-01

    Full Text Available There are different places in India where natural stone aggregates are not available for constructional work. Plastic coated OBBA can solve the problem of shortage of stone aggregate to some extent. The engineers are always encouraged to use locally available materials. The present investigation is carried out to evaluate the plastic coated OBBA as an alternative material for bituminous road construction. Shredded waste plastics are mixed with OBBA in different percentages as 0.38, 0.42, 0.46, 0.50, 0.54, and 0.60 of the weight of brick aggregates. Marshall Method of mix design is carried out to find the optimum bitumen content of such bituminous concrete mix prepared by plastic coated OBBA. Bulk density, Marshall Stability, flow, Marshall Quotient, ITS, TSR, stripping, fatigue life, and deformations have been determined accordingly. Marshall Stability value of 0.54 percent of plastic mix is comparatively higher than the other mixes except 0.60 percent of plastic mix. Test results are within the prescribed limit for 0.54 percent of plastic mix. There is a significant reduction in rutting characteristics of the same plastic mix. The fatigue life of the mix is also significantly higher. Thus plastic coated OBBA is found suitable in construction of bituminous concrete road.

  12. Plastic film materials for dosimetry of very large absorbed doses

    DEFF Research Database (Denmark)

    McLaughlin, W.L.; Miller, Arne; Abdel-Rahim, F.

    1985-01-01

    Most plastic films have limited response ranges for dosimetry because of radiation-induced brittleness, degradation, or saturation of the signal used for analysis (e.g. spectrophotometry) at high doses. There are, however, a few types of thin plastic films showing linearity of response even up...... to doses as high as 2 × 106 Gy (200 Mrad) without severe loss of mechanical properties. Among many candidate film types tested, those showing such resistance to radiation damage and continued response at such high doses are polyethylene terephthalate, high-density polyethylene, dyed polyvinylchloride...

  13. Behavioral plasticity is not signiifcantly associated withhead volume ina wild Chestnut Thrush (Turdus rubrocanus) population

    Institute of Scientific and Technical Information of China (English)

    Qingshan Zhao; Yuehua Sun

    2016-01-01

    Background: The drivers of intraspeciifc variation in behavioral plasticity are poorly known. A widely held hypothesis is that brain size is positively correlated with behavioral plasticity. Methods: A total of 71 Chestnut Thrushes (Turdus rubrocanus) were caught in the wild population. We quantiifed behavior plasticity of activity of individuals measured in the same cage across two contexts (common and with a novel object stimulation), using a random regression analysis. We then investigated whether head volume (a proxy for brain size) was associated with behavioral plasticity in activity level using Spearman rank-order correlation. Results: We found no signiifcant evidence that activity plasticity was associated with relative head volume. There was no sex difference in head volume or in variance in head volume. Conclusions: We speculate that the absence of an association between brain volume and activity behavior plasticity may result from the inaccuracy of using external skull measurements to estimate brain size, or from a particular part of the brain being responsible for plasticity in activity level.

  14. Radiological properties of plastics and TLD materials its application in radiation dosimetry

    Science.gov (United States)

    Jabaseelan Samuel, E. James; Srinivasan, K.; Poopathi, V.

    2017-05-01

    In the current study, we evaluated the tissue equivalency of nine different commonly used thermoluminescence compounds and six plastic materials over the photon energy range of 15 KeV to 20 MeV. Our result confirmed that the ratio of number of electrons per gram, electron density of the entire TLD compounds and plastic materials to ICRU-44 soft tissue was lesser than unity, except in the case of polypropylene plastics. The effective atomic number ratio of all the plastic materials was also <1 excluding Poly-vinyl-chloride, and for TLD lithium borate material, it was <1 others which showed the deviation with respect to photon energy. Mass attenuation coefficient (µ/ϼ), mass absorption coefficient (µen/ρ) was calculated and the results are discussed in this paper.

  15. Compendium of information on identification and testing of materials for plastic solar thermal collectors

    Energy Technology Data Exchange (ETDEWEB)

    McGinniss, V.D.; Sliemers, F.A.; Landstrom, D.K.; Talbert, S.G.

    1980-07-31

    This report is intended to organize and summarize prior and current literature concerning the weathering, aging, durability, degradation, and testing methodologies as applied to materials for plastic solar thermal collectors. Topics covered include (1) rate of aging of polymeric materials; (2) environmental factors affecting performance; (3) evaluation and prediction of service life; (4) measurement of physical and chemical properties; (5) discussion of evaluation techniques and specific instrumentation; (6) degradation reactions and mechanisms; (7) weathering of specific polymeric materials; and (8) exposure testing methodology. Major emphasis has been placed on defining the current state of the art in plastics degradation and on identifying information that can be utilized in applying appropriate and effective aging tests for use in projecting service life of plastic solar thermal collectors. This information will also be of value where polymeric components are utilized in the construction of conventional solar collectors or any application where plastic degradation and weathering are prime factors in material selection.

  16. Application of x-ray stress measurement to practical materials for plastic work

    Energy Technology Data Exchange (ETDEWEB)

    Sekiguchi, Haruo; Kiriyama, Sadao

    1987-09-01

    X-ray diffraction stress measurement is achieved commonly from calculating elastic strain of crystal lattice. Therefore, the accuracy of the measurement is apt to be influenced from plastic zone or preferred orientation of surface layer for the measurement of practical materials with strong plastic work. It was found that the Two-Axis Oscillation Method was suitable to improve the accuracy of measurement on those materials. This papar discussed on the mechanism of residual stress mode during the process of plastic work, and described the application results on the plastic worked materials, such as spring steel surface treated by shot peening, titanium alloy with preferred orientation and mechanically worked surface of SUS 304 materials.

  17. Evaluation Of Gas Diffusion Through Plastic Materials Used In Experimental And Sampling Equipment

    DEFF Research Database (Denmark)

    Kjeldsen, Peter

    1993-01-01

    Plastic materials are often used in experimental and sampling equipment. Plastics are not gas tight, since gases are able to diffuse through the walls of tubing and containers made of plastic. Methods for calculating the significance of gas diffusion through the walls of containers and the walls....... Calculations show that diffusion of oxygen through plastic tubing and reactors into anoxic water can be a serious problem for a series of plastic materials. Comparison of the method for turbulent and laminar flow in tubings shows that the difference is insignificant for most cases. Calculations show also...... that the use of silicone rubber in experimental and sampling equipment to be used for anoxic water is, for most cases, prohibited by oxygen diffusion....

  18. Plastic Fibre Reinforced Soil Blocks as a Sustainable Building Material

    Science.gov (United States)

    Prasad, C. K. Subramania; Nambiar, E. K. Kunhanandan; Abraham, Benny Mathews

    2012-10-01

    Solid waste management, especially the huge quantity of waste plastics, is one of the major environmental concerns nowadays. Their employability in block making in the form of fibres, as one of the methods of waste management, can be investigated through a fundamental research. This paper highlights the salient observations from a systematic investigation on the effect of embedded fibre from plastic waste on the performance of stabilised mud blocks. Stabilisation of the soil was done by adding cement, lime and their combination. Plastic fibre in chopped form from carry bags and mineral water bottles were added (0.1% & 0.2% by weight of soil) as reinforcement. The blocks were tested for density, and compressive strength, and observed failure patterns were analysed. Blocks with 0.1% of plastic fibres showed an increase in strength of about 3 to 10%. From the observations of failure pattern it can be concluded that benefits of fibre reinforcement includes both improved ductility in comparison with raw blocks and inhibition of crack propogation after its initial formation.

  19. The usage of plastic waste as a secondary raw material for the modification of sandcrete properties

    Science.gov (United States)

    Klovas, A.; Daukšys, M.; Venčkauskas, L.

    2015-03-01

    Recently the usage of various industry wastes as a secondary raw material tends to increase its relevancy. One of possible options to decrease the amount of waste is to use them to produce new products or materials. The operation of various secondary raw materials (tire rubber, tire cord, ground glass shards, ground ceramic waste products) during the concrete mixture preparation allows to change its as well as cured concrete properties. Recently polymer and steel fibers are used for concrete reinforcement. This study analyses the usage possibility of plastic shavings for the reinforcement of concrete. The technological properties of cement slurry (sand, fraction of 0/4 and 10 kg/m3, 15 kg/m3 and 20 kg/m3 of plastic shavings) as well as mechanical, physical and porosity properties of cured sandcrete were established during the experimental research. The geometric characteristics of mill-shredded plastic shavings were established. Experimental results revealed that the usage of plastic shavings decreased slurry slump and density. The minor decrease of cured sandcrete density (~2200 kg/m3) was noticed with the addition of plastic shavings within the limits of 10 - 20 kg/m3. The flexural strength of cured sandcrete increased from 36 % to 57 % compared with reference specimen (without plastic shavings). The dependence of flexural force and deflection was obtained. Study revealed that the residual strength after crack opening is bigger with the usage of plastic shavings as a secondary raw material compared with reference specimen.

  20. Modeling the Collisional-Plastic Stress Transition for Bin Discharge of Granular Material

    Science.gov (United States)

    Pannala, Sreekanth; Daw, C. Stuart; Finney, Charles E. A.; Benyahia, Sofiane; Syamlal, Madhava; O'Brien, Thomas J.

    2009-06-01

    We propose a heuristic model for the transition between collisional and frictional/plastic stresses in the flow of granular material. Our approach is based on a physically motivated, nonlinear `blending' function that produces a weighted average of the limiting stresses, depending on the local void fraction in the flow field. Previously published stress models are utilized to describe the behavior in the collisional (Lun et al., 1984) and quasi-static limits (Schaeffer, 1987 and Syamlal et al.., 1993). Sigmoidal and hyperbolic tangent functions are used to mimic the observed smooth yet rapid transition between the collisional and plastic stress zones. We implement our stress transition model in an open-source multiphase flow solver, MFIX (Multiphase Flow with Interphase eXchanges, www.mfix.org) and demonstrate its application to a standard bin discharge problem. The model's effectiveness is illustrated by comparing computational predictions to the experimentally derived Beverloo correlation. With the correct choice of function parameters, the model predicts bin discharge rates within the error margins of the Beverloo correlation and is more accurate than one of the alternative granular stress models proposed in the literature. Although a second granular stress model in the literature is also reasonably consistent with the Beverloo correlation, we propose that our alternative blending function is likely to be more adaptable to situations with more complex solids properties (e.g., `sticky' solids).

  1. Modeling the Collisional-Plastic Stress Transition for Bin Discharge of Granular Material

    Energy Technology Data Exchange (ETDEWEB)

    Pannala, Sreekanth [ORNL; Daw, C Stuart [ORNL; FINNEY, Charles E A [ORNL; Benyahia, S. [National Energy Technology Laboratory (NETL); Syamlal, M. [National Energy Technology Laboratory (NETL); O' Brien, T. J. [National Energy Technology Laboratory (NETL)

    2009-01-01

    We propose a heuristic model for the transition between collisional and frictional/plastic stresses in the flow of granular material. Our approach is based on a physically motivated, nonlinear blending function that produces a weighted average of the limiting stresses, depending on the local void fraction in the flow field. Previously published stress models are utilized to describe the behavior in the collisional (Lun et al., 1984) and quasi-static limits (Schaeffer, 1987 and Syamlal et al., 1993). Sigmoidal and hyperbolic tangent functions are used to mimic the observed smooth yet rapid transition between the collisional and plastic stress zones. We implement our stress transition model in an opensource multiphase flow solver, MFIX (Multiphase Flow with Interphase eXchanges, www.mfix.org) and demonstrate its application to a standard bin discharge problem. The model s effectiveness is illustrated by comparing computational predictions to the experimentally derived Beverloo correlation. With the correct choice of function parameters, the model predicts bin discharge rates within the error margins of the Beverloo correlation and is more accurate than one of the alternative granular stress models proposed in the literature. Although a second granular stress model in the literature is also reasonably consistent with the Beverloo correlation, we propose that our alternative blending function is likely to be more adaptable to situations with more complex solids properties (e.g., sticky solids).

  2. Optically stimulated luminescence of common plastic materials for accident dose reconstruction

    Energy Technology Data Exchange (ETDEWEB)

    Chang, I.; Lee, J. I.; Kim, J. L. [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Chung, K. S. [Gyeongsang National Univ., Jinju (Korea, Republic of)

    2014-05-15

    Optically stimulate luminescence(OSL) has many applications in a variety of radiation dosimetry fields, including personal dosimetry, environmental radiation level monitor, retrospective dosimetry for dating, and reconstruction of radiation doses from radiation accident. In the reconstruction of radiation doses from radiation accident, OSL technique has been used to estimate the doses exposed to public area through analysis of housewares or house construing materials. Recently, many efforts have been carried out for dose reconstruction using personal electronic devices such as mobile phones and USB memory chips. Some of natural minerals such as quartz and feldspar have OSL properties. Quartz is the second most abundant mineral in continental crust of the Earth. In some of common plastics, inorganic fillers (quartz, alumina etc.) are added to make strengthen of their properties depends on applications areas. The aim of this research is to explore a possibility of use of the common plastic materials for dose reconstruction in radiation accident case. In this research the OSL dose response-curve and fading characteristics of the common plastics were tested and evaluated. Finally, we expect this work contribute to elevate the possibility of the dose reconstruction. The general conclusion of this work is that the possibility of dose reconstruction using common plastic materials is showed using the OSL characteristics of the materials. However, the tested common plastic materials have relatively low sensitivities. Further work is required to establish a database of OSL properties of common plastic materials for emergency dose reconstruction by using housewares.

  3. Multiscale Modeling of Structurally-Graded Materials Using Discrete Dislocation Plasticity Models and Continuum Crystal Plasticity Models

    Science.gov (United States)

    Saether, Erik; Hochhalter, Jacob D.; Glaessgen, Edward H.

    2012-01-01

    A multiscale modeling methodology that combines the predictive capability of discrete dislocation plasticity and the computational efficiency of continuum crystal plasticity is developed. Single crystal configurations of different grain sizes modeled with periodic boundary conditions are analyzed using discrete dislocation plasticity (DD) to obtain grain size-dependent stress-strain predictions. These relationships are mapped into crystal plasticity parameters to develop a multiscale DD/CP model for continuum level simulations. A polycrystal model of a structurally-graded microstructure is developed, analyzed and used as a benchmark for comparison between the multiscale DD/CP model and the DD predictions. The multiscale DD/CP model follows the DD predictions closely up to an initial peak stress and then follows a strain hardening path that is parallel but somewhat offset from the DD predictions. The difference is believed to be from a combination of the strain rate in the DD simulation and the inability of the DD/CP model to represent non-monotonic material response.

  4. Deformation and fatigue behavior of SSME turbopump blade materials

    Science.gov (United States)

    Milligan, Walter W.; Antolovich, Stephen D.

    1987-01-01

    Directionally solidified and single crystal superalloys which are intended for use as turbopump blade materials are anisotropic both elastically and plastically. Therefore, isotropic constitutive models must be modified. Several models which are now being developed are based on metallurgical theories of deformation in these types of alloys. However, these theories have not been fully justified, and the temperature and strain regimes over which they may be valid are poorly defined. The objective of this work is to study the deformation behavior of the alloys, in order to determine the validity of these models and to thereby support the ongoing research efforts in solid mechanics.

  5. BIOFILTERS IN WASTEWATER TREATMENT AFTER RECYCLED PLASTIC MATERIALS

    Directory of Open Access Journals (Sweden)

    Irena Kania-Surowiec

    2014-10-01

    Full Text Available In this paper the possibility of using biological deposits in wastewater treatment of recycled plastics were presented. There are many aspects of this issue that should be considered to be able to use information technology solutions in the industry. This includes, inter alia, specify the types of laboratory tests based on the analysis of changes in the fluid during the wastewater treatment process, knowledge and selection factors for proper growth of biofilm in the deposit and to develop the right concept and a prototype for a particular processing plant, plastic processing plant. It is possible to determine the parameters that will increase the efficiency of sewage treatment while minimizing the financial effort on the part of the Company. Selection methods of wastewater treatment is also associated with the environmental strategy of the country at the enterprise level specified in the Environmental Policy. This is an additional argument for the use of biological methods in the treatment of industrial waste water.

  6. Plastic film materials for dosimetry of very large absorbed doses

    DEFF Research Database (Denmark)

    McLaughlin, W.L.; Miller, Arne; Abdel-Rahim, F.

    1985-01-01

    of the polyhalostyrenes have essentially rate-independent and moderately temperature-dependent responses to such large doses of ionizing radiation. While radiation-induced optical absorption in the ultraviolet for polystyrene is unstable following irradiation, thus leading to an intrinsic low-intensity rate dependence......Most plastic films have limited response ranges for dosimetry because of radiation-induced brittleness, degradation, or saturation of the signal used for analysis (e.g. spectrophotometry) at high doses. There are, however, a few types of thin plastic films showing linearity of response even up...... to doses as high as 2 × 106 Gy (200 Mrad) without severe loss of mechanical properties. Among many candidate film types tested, those showing such resistance to radiation damage and continued response at such high doses are polyethylene terephthalate, high-density polyethylene, dyed polyvinylchloride...

  7. A model for plasticity kinetics and its role in simulating the dynamic behavior of Fe at high strain rates

    Energy Technology Data Exchange (ETDEWEB)

    Colvin, J D; Minich, R W; Kalantar, D H

    2007-03-29

    The recent diagnostic capability of the Omega laser to study solid-solid phase transitions at pressures greater than 10 GPa and at strain rates exceeding 10{sup 7} s{sup -1} has also provided valuable information on the dynamic elastic-plastic behavior of materials. We have found, for example, that plasticity kinetics modifies the effective loading and thermodynamic paths of the material. In this paper we derive a kinetics equation for the time-dependent plastic response of the material to dynamic loading, and describe the model's implementation in a radiation-hydrodynamics computer code. This model for plasticity kinetics incorporates the Gilman model for dislocation multiplication and saturation. We discuss the application of this model to the simulation of experimental velocity interferometry data for experiments on Omega in which Fe was shock compressed to pressures beyond the {alpha}-to-{var_epsilon} phase transition pressure. The kinetics model is shown to fit the data reasonably well in this high strain rate regime and further allows quantification of the relative contributions of dislocation multiplication and drag. The sensitivity of the observed signatures to the kinetics model parameters is presented.

  8. Multi-scale modeling and experimental study of twin inception and propagation in hexagonal close-packed materials using a crystal plasticity finite element approach; part II: Local behavior

    Science.gov (United States)

    Abdolvand, Hamidreza; Daymond, Mark R.

    2013-03-01

    In-situ tensile tests are performed on Zircaloy-2 samples with various grain sizes to study twin inception and propagation. Orientation maps of some areas at the surface are measured before and after deformation, using the Electron BackScattered Diffraction (EBSD) technique. Strain fields of the same areas are determined using the digital image correlation technique and are compared with results from Crystal Plasticity Finite Element (CPFE) simulations. Different assumptions are made within the CPFE code to simulate twin propagation. It is observed that the predictions of different models does not really change from one model to another when statistical information on the twins is compared, yet local predictions for each grain, i.e. twin direction, twin variant selection, and twin inception site, do change. Also, it is shown that the twin Schmid factor can vary drastically within grains and that for those grains with a low tendency for twinning this variation may make them susceptible to twinning.

  9. Modeling the time-dependent flexural response of wood-plastic composite materials

    Science.gov (United States)

    Hamel, Scott E.

    Wood-plastic composites (WPCs) are moisture sensitive bimodal anisotropic nonlinear viscoelastic materials, with time and temperature having the greatest effect on mechanical behavior. As WPC producers seek to manufacture structural bending members, such as beams and joists, it is important that the material's time and temperature-dependent mechanical behavior be understood and characterized. The complicated time-dependent behavior means that WPC bending deflections cannot be adequately predicted for even practical design purposes using simple linear-elastic models. Instead, mechanics-based models that incorporate the observed time-dependent and nonlinear responses are necessary. This dissertation presents an experimental and modeling program used to test and characterize the axial and shear behaviors of seven different WPC products (primarily polyethylene and polypropylene) subjected to both quasi-static and creep loading at multiple temperatures. These data were used to develop a mechanics based model that can predict bending deflections of complex sections at any time or temperature. Additionally, a practical design method and standardized test procedures were created for use in typical long-term bending situations. A mechanical model for WPCs must combine time-dependent material characterization with a tool that can simulate mode dependence, temperature dependence, changing neutral axis location, and nonlinear axial stress distributions that vary over the length of a member and evolve with time. Finite-element (FE) modeling was chosen as the most practical way to satisfy these requirements. The model developed in this study uses an FE model with a custom-designed material model. Bending deflection predictions from the model were compared to experimental testing and the model showed some success despite the difficulties created by the material variability. The practical method created for designing WPC structural bending members utilizes four material constants

  10. Innovative use of wood-plastic-composites (WPC) as a core material in the sandwich injection molding process

    Science.gov (United States)

    Moritzer, Elmar; Martin, Yannick

    2016-03-01

    The demand for materials based on renewable raw materials has risen steadily in recent years. With society's increasing interest for climate protection and sustainability, natural-based materials such as wood-plastic-composites (WPC) have gained market share thanks to their positive reputation. Due to advantages over unreinforced plastics such as cost reduction and weight savings it is possible to use WPC in a wide area of application. Additionally, an increase in mechanical properties such as rigidity and strength is achieved by the fibers compared to unreinforced polymers. The combination of plastic and wood combines the positive properties of both components in an innovative material. Despite the many positive properties of wood-plastic-composite, there are also negative characteristics that prevent the use of WPC in many product areas, such as automotive interiors. In particular, increased water intake, which may result in swelling of near-surface particles, increased odor emissions, poor surface textures and distortion of the components are unacceptable for many applications. The sandwich injection molding process can improve this situation by eliminating the negative properties of WPC by enclosing it with a pure polymer. In this case, a layered structure of skin and core material is produced, wherein the core component is completely enclosed by the skin component. The suitability of WPC as the core component in the sandwich injection molding has not yet been investigated. In this study the possibilities and limitations of the use of WPC are presented. The consideration of different fiber types, fiber contents, skin materials and its effect on the filling behavior are the focus of the presented analysis.

  11. Charges for plastic bags : Motivational and behavioral effects

    NARCIS (Netherlands)

    Jakovcevic, Adriana; Steg, Linda; Mazzeo, Nadia; Caballero, Romina; Franco, Paul; Putrino, Natalia; Favara, Jesica

    2014-01-01

    Two field studies tested the effects of a charge for single-use plastic bags recently implemented in Buenos Aires City, Argentina. Study 1 showed a greater increase in consumers' own bag use after the charge was introduced in supermarkets where the policy was introduced, in comparison to control sup

  12. Polarimetric scattering behavior of materials at terahertz frequencies

    Science.gov (United States)

    DiGiovanni, David Anthony

    Terahertz spectroscopic techniques have long been used to characterize the electromagnetic behavior of materials for use in radar, astronomy, and remote sensing applications. Spectroscopic information is valuable, but additional information about materials is present in the polarization of the scattered radiation. This thesis has investigated the polarimetric scattering behavior of various rough dielectric and metallic materials from 100 GHz to 1.55 THz. Common building materials and terrain, such as sand, gravel, soil, concrete, and roofing shingles, were studied. In order to obtain a better understanding of basic rough surface scattering phenomenology in this region of the spectrum, roughened metal and plastic samples were studied as well. The scattering behavior of these materials was studied as a function of incident angle, roughness, frequency, and polarization. Theoretical scattering models were used to compare measured results to theoretical predictions. Good agreement was observed between scattering measurements and theoretical predictions based on the small perturbation theory for the roughened metal surfaces. However, a substantial disagreement was observed for the rough dielectric surfaces and is discussed.

  13. An experimental study of plastic deformation of materials

    DEFF Research Database (Denmark)

    Knudsen, Tine

    in the investigated hot deformed samples (lnZ= 27.5 to 32) in general are cell block structures, and that the alignment of the cell block boundaries at low strain depends on the grain orientation, often in the same manner as in cold deformation. Part II investigates the energy stored in the dislocation structure...... after cold deformation by calorimetry and by analysis of the dislocation structure. The stored energy measured by calorimetry is found to be larger than that determined from the dislocation structure by a factor between 1.9 and 2.7, and this factor decreases with the plastic strain. Part III aimed...

  14. Severe plastic deformation using friction stir processing, and the characterization of microstructure and mechanical behavior using neutron diffraction

    Science.gov (United States)

    Woo, Wanchuck

    Friction-stir welding (FSW) is a solid-state joining process, which utilizes a cylindrical rotating tool consisting of a concentric threaded tool pin and tool shoulder. The strong metallurgical bonding during the FSW is accomplished through: (1) the severe plastic deformation caused by the rotation of the tool pin that plunges into the material and travels along the joining line; and (2) the frictional heat generated mainly from the pressing tool shoulder. Recently, a number of variations of the FSW have been applied to modify the microstructure, for example, grain refinements and homogenization of precipitate particles, namely friction-stir processing (FSP). Applications of the FSP/FSW are widespread for the transportation industries. The microstructure and mechanical behavior of light-weight materials subjected to the FSW/FSP are being studied extensively. However, separating the effect of the frictional heat and severe plastic deformation on the residual stress and texture has been a standing problem for the fundamental understanding of FSW/FSP. The fundamental issues are: (i) the heat- and plastic-deformation-induced internal stresses that may be detrimental to the integrity and performance of components; (ii) the frictional heating that causes a microstructural softening due to the dissolution or growth of the precipitates in precipitation-hardenable Al alloys during the process; and (iii) the crystallographic texture can be significantly altered from the original texture, which could affect the physical and mechanical properties. The understanding of the influences of the de-convoluted sources (e.g. frictional heat, severe plastic deformation, or their combination) on the residual stress, microstructural softening, and texture variations during FSW can be used for a physicsvi based optimization of the processing parameters and new tool designs. Furthermore, the analyses and characterization of the natural aging behavior and the aging kinetics can be

  15. The Effects of Weathering on Mechanical Properties of Glass Fiber Reinforced Plastics (Grp) Materials

    OpenAIRE

    Abdullah, H.; S. Al Araimi and R. A. Siddiqui

    2012-01-01

    Glass fiber reinforced plastics composite is extensively used as a structural material for pools, oil pipes and tanks because it has good corrosion resistance properties.  The effects of weathering on the mechanical properties of glass fiber reinforced plastics (GRP) in the Sultanate of Oman have been studied.  The tensile and three point bend specimens were exposed to outdoor conditions (open atmosphere) in sunlight and tested for various intervals of time.  It was observed th...

  16. Molecular dynamics simulation of the plastic behavior anisotropy of shock-compressed monocrystal nickel

    Science.gov (United States)

    Chen, Ya-Zhou; Zhou, Liu-Cheng; He, Wei-Feng; Sun, Yu; Li, Ying-Hong; Jiao, Yang; Luo, Si-Hai

    2017-01-01

    Molecular dynamics simulations were used to study the plastic behavior of monocrystalline nickel under shock compression along the [100] and [110] orientations. The shock Hugoniot relation, local stress curve, and process of microstructure development were determined. Results showed the apparent anisotropic behavior of monocrystalline nickel under shock compression. The separation of elastic and plastic waves was also obvious. Plastic deformation was more severely altered along the [110] direction than the [100] direction. The main microstructure phase transformed from face-centered cubic to body-centered cubic and generated a large-scale and low-density stacking fault along the family of { 111 } crystal planes under shock compression along the [100] direction. By contrast, the main mechanism of plastic deformation in the [110] direction was the nucleation of the hexagonal, close-packed phase, which generated a high density of stacking faults along the [110] and [1̅10] directions.

  17. Finite element analysis of 3D elastic-plastic frictional contact problem for Cosserat materials

    Science.gov (United States)

    Zhang, S.; Xie, Z. Q.; Chen, B. S.; Zhang, H. W.

    2013-06-01

    The objective of this paper is to develop a finite element model for 3D elastic-plastic frictional contact problem of Cosserat materials. Because 3D elastic-plastic frictional contact problems belong to the unspecified boundary problems with nonlinearities in both material and geometric forms, a large number of calculations are needed to obtain numerical results with high accuracy. Based on the parametric variational principle and the corresponding quadratic programming method for numerical simulation of frictional contact problems, a finite element model is developed for 3D elastic-plastic frictional contact analysis of Cosserat materials. The problems are finally reduced to linear complementarity problems (LCP). Numerical examples show the feasibility and importance of the developed model for analyzing the contact problems of structures with materials which have micro-polar characteristics.

  18. Steady State Crack Propagation in Layered Material Systems Displaying Visco-plastic Behaviour

    DEFF Research Database (Denmark)

    Nielsen, Kim Lau

    2012-01-01

    The steady state fracture toughness of elastic visco-plastic materials is studied numerically, using both a conventional and a higher order model. Focus is on the combined effect of strain hardening, strain gradient hardening and strain rate hardening on cracking in layered material systems...

  19. Activin receptor signaling regulates cocaine-primed behavioral and morphological plasticity.

    Science.gov (United States)

    Gancarz, Amy M; Wang, Zi-Jun; Schroeder, Gabrielle L; Damez-Werno, Diane; Braunscheidel, Kevin M; Mueller, Lauren E; Humby, Monica S; Caccamise, Aaron; Martin, Jennifer A; Dietz, Karen C; Neve, Rachael L; Dietz, David M

    2015-07-01

    Activin receptor signaling, including the transcription factor Smad3, was upregulated in the rat nucleus accumbens (NAc) shell following withdrawal from cocaine. Direct genetic and pharmacological manipulations of this pathway bidirectionally altered cocaine seeking while governing morphological plasticity in NAc neurons. Thus, Activin/Smad3 signaling is induced following withdrawal from cocaine, and such regulation may be a key molecular mechanism underlying behavioral and cellular plasticity in the brain following cocaine self-administration.

  20. Structural Transformations in Metallic Materials During Plastic Deformation

    Science.gov (United States)

    Zasimchuk, E.; Turchak, T.; Baskova, A.; Chausov, N.; Hutsaylyuk, V.

    2017-03-01

    In this paper, the structure formation during the plastic deformation of polycrystalline nickel and aluminum based alloy 2024-T3 is investigated. The possibility of the relaxation and synergetic structure formation is examined. It is shown the deformation softening to be due to the crystallization of the amorphous structure of hydrodynamics flow channels (synergetic structure) HC as micrograins and their subsequent growth. The possible mechanism of micrograins' growth is proposed. The deformation processes change the phase composition of the multiphase alloy 2024-T3. It is shown by the quantitative analysis of the structures which were deformed in different regimes of the alloy samples. A method for increasing of the fatigue life through a dynamic pre-deformation is suggested.

  1. Structural Transformations in Metallic Materials During Plastic Deformation

    Science.gov (United States)

    Zasimchuk, E.; Turchak, T.; Baskova, A.; Chausov, N.; Hutsaylyuk, V.

    2017-02-01

    In this paper, the structure formation during the plastic deformation of polycrystalline nickel and aluminum based alloy 2024-T3 is investigated. The possibility of the relaxation and synergetic structure formation is examined. It is shown the deformation softening to be due to the crystallization of the amorphous structure of hydrodynamics flow channels (synergetic structure) HC as micrograins and their subsequent growth. The possible mechanism of micrograins' growth is proposed. The deformation processes change the phase composition of the multiphase alloy 2024-T3. It is shown by the quantitative analysis of the structures which were deformed in different regimes of the alloy samples. A method for increasing of the fatigue life through a dynamic pre-deformation is suggested.

  2. Thermal expansion behavior of co-extruded wood-plastic composites with glass-fiber reinforced shells

    Directory of Open Access Journals (Sweden)

    Runzhou Huang

    2012-11-01

    Full Text Available Coextruded wood-plastic composites (WPCs with glass-fiber (GF filled shells were manufactured, and their thermal expansion behavior was studied. A three-dimensional finite element model (FEM considering differential properties of both shell and core layers was developed to predict the linear coefficient of thermal expansion (LCTE of the material. It was shown that the LCTE values varied with composite structure and composition (i.e., core-shell thicknesses and materials. The use of GF-filled shells helped lower overall composite LCTE values. The imbalance of shell and core LCTE, and their moduli led to complex stress fields within a given composite system. The FEM predicted a trend of LCTE change with varying composite structures, which was in good agreement with the experimental data. This study provides for the first time a finite element modeling technique to optimize raw material composition and composite structure for optimizing thermal expansion behavior of co-extruded WPCs.

  3. Membrane behavior of clay liner materials

    Science.gov (United States)

    Kang, Jong Beom

    Membrane behavior represents the ability of porous media to restrict the migration of solutes, leading to the existence of chemico-osmosis, or the flow of liquid in response to a chemical concentration gradient. Membrane behavior is an important consideration with respect to clay soils with small pores and interactive electric diffuse double layers associated with individual particles, such as bentonite. The results of recent studies indicate the existence of membrane behavior in bentonite-based hydraulic barriers used in waste containment applications. Thus, measurement of the existence and magnitude of membrane behavior in such clay soils is becoming increasingly important. Accordingly, this research focused on evaluating the existence and magnitude of membrane behavior for three clay-based materials that typically are considered for use as liners for waste containment applications, such as landfills. The three clay-based liner materials included a commercially available geosynthetic clay liner (GCL) consisting of sodium bentonite sandwiched between two geotextiles, a compacted natural clay known locally as Nelson Farm Clay, and compacted NFC amended with 5% (dry wt.) of a sodium bentonite. The study also included the development and evaluation of a new flexible-wall cell for clay membrane testing that was used subsequently to measure the membrane behaviors of the three clay liner materials. The consolidation behavior of the GCL under isotropic states of stress also was evaluated as a preliminary step in the determination of the membrane behavior of the GCL under different effective consolidation stresses.

  4. Mechanisms of plastic deformation for powder materials in cold working

    Institute of Scientific and Technical Information of China (English)

    张连洪; 李双义

    2003-01-01

    To deal with the discontinuity of particulate media and subsequent uncertainty of stress, based on the probability theory for mechanics of particulate media, Mohr-Coulomb yield criterion of particulate media, and the theory of crystal deformation, we put forward the statistical mechanisms of deformation of powder materials in cold working and mechanism of texture development of the high temperature superconducting wire/tape. A new yield criterion of powder materials is proposed.

  5. Modeling shock responses of plastic bonded explosives using material point method

    Science.gov (United States)

    Shang, Hailin; Zhao, Feng; Fu, Hua

    2017-01-01

    Shock responses of plastic bonded explosives are modeled using material point method as implemented in the Uintah Computational Framework. Two-dimensional simulation model was established based on the micrograph of PBX9501. Shock loading for the explosive was performed by a piston moving at a constant velocity. Unreactive simulation results indicate that under shock loading serious plastic strain appears on the boundary of HMX grains. Simultaneously, the plastic strain energy transforms to thermal energy, causing the temperature to rise rapidly on grain boundary areas. The influence of shock strength on the responses of explosive was also investigated by increasing the piston velocity. And the results show that with increasing shock strength, the distribution of plastic strain and temperature does not have significant changes, but their values increase obviously. Namely, the higher the shock strength is, the higher the temperature rise will be.

  6. Analysis of linear elasticity and non-linearity due to plasticity and material damage in woven and biaxial braided composites

    Science.gov (United States)

    Goyal, Deepak

    Textile composites have a wide variety of applications in the aerospace, sports, automobile, marine and medical industries. Due to the availability of a variety of textile architectures and numerous parameters associated with each, optimal design through extensive experimental testing is not practical. Predictive tools are needed to perform virtual experiments of various options. The focus of this research is to develop a better understanding of linear elastic response, plasticity and material damage induced nonlinear behavior and mechanics of load flow in textile composites. Textile composites exhibit multiple scales of complexity. The various textile behaviors are analyzed using a two-scale finite element modeling. A framework to allow use of a wide variety of damage initiation and growth models is proposed. Plasticity induced non-linear behavior of 2x2 braided composites is investigated using a modeling approach based on Hill's yield function for orthotropic materials. The mechanics of load flow in textile composites is demonstrated using special non-standard postprocessing techniques that not only highlight the important details, but also transform the extensive amount of output data into comprehensible modes of behavior. The investigations show that the damage models differ from each other in terms of amount of degradation as well as the properties to be degraded under a particular failure mode. When compared with experimental data, predictions of some models match well for glass/epoxy composite whereas other's match well for carbon/epoxy composites. However, all the models predicted very similar response when damage factors were made similar, which shows that the magnitude of damage factors are very important. Full 3D as well as equivalent tape laminate predictions lie within the range of the experimental data for a wide variety of braided composites with different material systems, which validated the plasticity analysis. Conclusions about the effect of

  7. Phase field crystal study of deformation and plasticity in nanocrystalline materials.

    Science.gov (United States)

    Stefanovic, Peter; Haataja, Mikko; Provatas, Nikolas

    2009-10-01

    We introduce a modified phase field crystal (MPFC) technique that self-consistently incorporates rapid strain relaxation alongside the usual plastic deformation and multiple crystal orientations featured by the traditional phase field crystal (PFC) technique. Our MPFC formalism can be used to study a host of important phase transformation phenomena in material processing that require rapid strain relaxation. We apply the MPFC model to study elastic and plastic deformations in nanocrystalline materials, focusing on the "reverse" Hall-Petch effect. Finally, we introduce a multigrid algorithm for efficient numerical simulations of the MPFC model.

  8. Validation of the material point method and plasticity with Taylor impact tests

    CERN Document Server

    Banerjee, Biswajit

    2012-01-01

    Taylor impacts tests were originally devised to determine the dynamic yield strength of materials at moderate strain rates. More recently, such tests have been used extensively to validate numerical codes for the simulation of plastic deformation. In this work, we use the material point method to simulate a number of Taylor impact tests to compare different Johnson-Cook, Mechanical Threshold Stress, and Steinberg-Guinan-Cochran plasticity models and the vob Mises and Gurson-Tvergaard-Needleman yield conditions. In addition to room temperature Taylor tests, high temperature tests have been performed and compared with experimental data.

  9. Experimental investigation and numerical simulation of plastic flow behavior during forward-backward-radial extrusion process

    Directory of Open Access Journals (Sweden)

    A. Farhoumand

    2016-12-01

    Full Text Available Finite element method was employed to investigate the effect of process parameters of plastic deformation behavior in Forward-Backward-Radial Extrusion (FBRE process. The result of an axisymmetric model shows that the friction between die components and the sample has a substantial effect on the material flow behavior. Although strain heterogeneity index (SHI slightly decreases with an increase in friction, large portion of the sample experiences significant strain heterogeneity. Increasing the friction factor also localizes the strain heterogeneity effect in the backward section, and spread the effect in the forward section. Decreasing the friction in the FBRE process can reduce the amount of the strain heterogeneity in the product while decreases the required punch force substantially. Furthermore, an increase in gap thickness increases the deformation in the area close to the lower punch at the expense of the area in the vicinity of the upper punch. The numerical simulation has a good agreement with the experimental results which confirms the accuracy of the proposed finite element model.

  10. Influence of plasticizer content on the transition of electromechanical behavior of PVC gel actuator.

    Science.gov (United States)

    Ali, Mohammad; Ueki, Takamitsu; Tsurumi, Daijiro; Hirai, Toshihiro

    2011-06-21

    The actuation performance of plasticized poly(vinyl chloride) (PVC) gel actuators in an electric field depends on their chemical composition and electrical and mechanical properties. The influence of plasticizer (dibutyl adipate) content on electromechanical behavior of PVC gels was investigated by impedance spectroscopy and space charge measurement. By plasticizing the PVC, the dielectric constant and space charge density of PVC gel were drastically increased at 1:2 w/w ratio of PVC to plasticizer. To apply the results obtained from the impedance spectroscopy and space charge measurement, electrostatic adhesive forces generated between the PVC gel and the anode were measured. The electrostatic adhesive force at the anode was also dramatically increased at the same plasticizer content. All of the results indicated a transition of electromechanical behavior of PVC gel in the electric field, which was considered to originate from the orientation of polarized plasticizer molecules and dipole rotation of PVC chains. By using the electrostatic adhesive force of PVC gel derived from the electromechanical transition, a new electroactive actuator can be developed for novel applications.

  11. From waste plastics to industrial raw materials: A life cycle assessment of mechanical plastic recycling practice based on a real-world case study.

    Science.gov (United States)

    Gu, Fu; Guo, Jianfeng; Zhang, Wujie; Summers, Peter A; Hall, Philip

    2017-12-01

    Mechanical recycling of waste plastics is an environmental solution to the problem of waste plastic disposal, and has already become a common practice in industry. However, limited information can be found on either the industralised plastic recycling or the recycled materials, despite the use of recycled plastics has already extended to automobile production. This study investigates the life cycle environmental impacts of mechanical plastic recycling practice of a plastic recycling company in China. Waste plastics from various sources, such as agricultural wastes, plastic product manufacturers, collected solid plastic wastes and parts dismantled from waste electric and electronic equipments, are processed in three routes with products end up in different markets. The results of life cycle assessments show that the extrusion process has the largest environmental impacts, followed by the use of fillers and additives. Compared to production of virgin plastics and composites, the mechanical recycling is proved to be a superior alternative in most environmental aspects. Substituting virgin plastic composites with recycled plastic composites has achieved the highest environmental benefits, as virgin composite production has an impact almost 4 times higher that of the recycled composite production in each ReCiPe endpoint damage factor. Sensitivity analysis shows that the coverage of collecting network contribute affect little to overall environmental impact, and centralisation plays an important role in reducing overall environmental impacts. Among the fillers and additives, impact modifiers account for the most significant contributions to the environmental impacts of recycled composites. This study provides necessary information about the existing industrialised plastic recycling practice, and recommendations are given. Research implications are presented with the purpose to achieve higher substitution rate and lower environmental impact. Copyright © 2017 Elsevier B

  12. Study of an athermal quasi static plastic deformation in a 2D granular material

    Science.gov (United States)

    Zhang, Jie; Zheng, Jie

    2016-11-01

    In crystalline materials, the plasticity has been well understood in terms of dynamics of dislocation, i.e. flow defects in the crystals where the flow defects can be directly visualized under a microscope. In a contrast, the plasticity in amorphous materials, i.e. glass, is still poorly understood due to the disordered nature of the materials. In this talk, I will discuss the recent results we have obtained in our ongoing research of the plasticity of a 2D glass in the athermal quasi static limit where the 2D glass is made of bi-disperse granular disks with very low friction. Starting from a densely packed homogeneous and isotropic initial state, we apply pure shear deformation to the system. For a sufficiently small strain, the response of the system is linear and elastic like; when the strain is large enough, the plasticity of the system gradually develops and eventually the shear bands are fully developed. In this study, we are particularly interested in how to relate the local plastic deformation to the macroscopic response of the system and also in the development of the shear bands.

  13. Feasibility Study of Sensor Aided Impact Acoustic Sorting of Plastic Materials from End-of-Life Vehicles (ELVs

    Directory of Open Access Journals (Sweden)

    Jiu Huang

    2015-12-01

    Full Text Available The purpose of this feasibility research was to study a novel sensor based separation method for recycling of plastic materials from end-of-life vehicles (ELVs by using eigen-frequency response of impact acoustic emission. In this research three kinds of commonly used plastics, polypropylene (PP, acrylonitrile-butadiene-styrene (ABS, and styrene-maleic-anhydride (SMA sampled from end-of-life vehicles, were researched. Almost all the crushed plastic scraps had a flake structure, theoretically their impact response behaviors were determined by their diameters and thicknesses. The equivalent diameters of the scraps were characterized by fine sieving and their thicknesses were measured online by a 3D laser triangulation sensor above the conveying path. Following this the scraps were free dropped one-by-one to impact with an impact passive body on which impact acoustic emission (AE signals were generated and acquired by an acoustic pickup sensor. Thirdly, the AE signals which carried eigen-frequency response features were processed and characterized. Results demonstrated that the scraps with diameters < 8 mm were too weak for the actual devices to process; the scraps with diameter from 8–13 mm still generated quite a lot of AE signals of inadequate intensity. Finally the general characterization and recognition yields were 64.6%, 61.7%, and 63.9% of PP, ABS, and SMA in mass, respectively of tested materials.

  14. TG-MS study of the thermo-oxidative behavior of plastic automobile shredder residues.

    Science.gov (United States)

    Guo, Qingjie; Zhang, Xuan; Li, Chao; Liu, Xinmin; Li, Jinhui

    2012-03-30

    Automobile shredder residues (ASR) are materials that are rejected in the metal recovery process for end-of-life vehicles (ELV). These residues are composed of such materials as plastics, foams, glasses, rubbers, textiles, remaining metals and soils. ASR disposal is a difficult task, due to increasingly restrictive re-use policies. The pyrolytic reuse of ASR is one important option for energy recovery. The gas release behavior of pyrolyzed ASR was measured using a TG-MS apparatus, and this thermo-oxidative process was observed under different N(2)/O(2) volume ratios. The final weight/initial residue weight ratio for pyrolyzed ASR decreased from 43.4% to 10.1% with increasing oxygen concentrations. The production rates of hydrogen, methane and carbon dioxide also varied with different N(2)/O(2) volume ratios. The maximum emission of hydrogen and methane occurred when the thermo-oxidative atmosphere was entirely N(2). Temperature had a positive impact on hydrogen production, and the methane emission ratio reached a peak at the second shoulder of the devolatilization stage during which stage organic polymers were emitted. A peculiar characteristic of ASR is its content of nitrogen. The effects of ASR nitrogen content on N(2)O and NO(X) emissions were investigated in detail. NH(3) was the dominant nitrogen species that was released during ASR pyrolysis. N(2)O is highly temperature-sensitive and decomposes to N(2) at temperatures greater than 900°C.

  15. Chemistry with Inexpensive Materials: Spray Bottles and Plastic Bags.

    Science.gov (United States)

    Zoltewicz, Susan

    1993-01-01

    Presents eight chemistry activities that are interesting and involve simple, easily available materials. Topics include mystery writing, valentine hearts, flame tests, evaporation race, buoyancy versus mass, determination of relative masses of gases, mole sample container, and cold and hot packs. (DDR)

  16. Mathematical model predicts the elastic behavior of composite materials

    Directory of Open Access Journals (Sweden)

    Zoroastro de Miranda Boari

    2005-03-01

    Full Text Available Several studies have found that the non-uniform distribution of reinforcing elements in a composite material can markedly influence its characteristics of elastic and plastic deformation and that a composite's overall response is influenced by the physical and geometrical properties of its reinforcing phases. The finite element method, Eshelby's method and dislocation mechanisms are usually employed in formulating a composite's constitutive response. This paper discusses a composite material containing SiC particles in an aluminum matrix. The purpose of this study was to find the correlation between a composite material's particle distribution and its resistance, and to come up with a mathematical model to predict the material's elastic behavior. The proposed formulation was applied to establish the thermal stress field in the aluminum-SiC composite resulting from its fabrication process, whereby the mixture is prepared at 600 °C and the composite material is used at room temperature. The analytical results, which are presented as stress probabilities, were obtained from the mathematical model proposed herein. These results were compared with the numerical ones obtained by the FEM method. A comparison of the results of the two methods, analytical and numerical, reveals very similar average thermal stress values. It is also shown that Maxwell-Boltzmann's distribution law can be applied to identify the correlation between the material's particle distribution and its resistance, using Eshelby's thermal stresses.

  17. Implicit integration of plasticity models for granular materials

    DEFF Research Database (Denmark)

    Ahadi, A.; Krenk, Steen

    2003-01-01

    A stress integration algorithm for granular materials based on fully implicit integration with explicit updating is presented. In the implicit method the solution makes use of the gradient to the potential surface at the final stress state which is unknown. The final stress and hardening parameters...... are determined solving the non-linear equations iteratively so that the stress increment fulfills the consistency condition. The integration algorithm is applicable for models depending on all the three stress invariants and it is applied to a characteristic state model for granular material. Since tensile...... of the integration algorithm are illustrated by simulating both drained and undrained triaxial tests on sand. The algorithm is developed in a standard format which can be implemented in several general purpose finite element codes. It has been implemented as an ABAQUS subroutine, and a traditional geotechnical...

  18. PLASTICITY OF SELECTED METALLIC MATERIALS IN DYNAMIC DEFORMATION CONDITIONS

    OpenAIRE

    2014-01-01

    Characteristics of a modernized flywheel machine has been presented in the paper. The laboratory stand enables to perform dynamic tensile tests and impact bending with a linear velocity of the enforcing element in the range of 5÷40 m/s. A new data acquisition system, based on the tensometric sensors, allows for significant qualitative improvement of registered signals. Some preliminary dynamic forming tests were performed for the selected group of metallic materials. Subsequent microstruct...

  19. Crash simulation of hybrid structures considering the stress and strain rate dependent material behavior of thermoplastic materials

    Science.gov (United States)

    Hopmann, Ch.; Schöngart, M.; Weber, M.; Klein, J.

    2015-05-01

    Thermoplastic materials are more and more used as a light weight replacement for metal, especially in the automotive industry. Since these materials do not provide the mechanical properties, which are required to manufacture supporting elements like an auto body or a cross bearer, plastics are combined with metals in so called hybrid structures. Normally, the plastics components are joined to the metal structures using different technologies like welding or screwing. Very often, the hybrid structures are made of flat metal parts, which are stiffened by a reinforcement structure made of thermoplastic materials. The loads on these structures are very often impulsive, for example in the crash situation of an automobile. Due to the large stiffness variation of metal and thermoplastic materials, complex states of stress and very high local strain rates occur in the contact zone under impact conditions. Since the mechanical behavior of thermoplastic materials is highly dependent on these types of load, the crash failure of metal plastic hybrid parts is very complex. The problem is that the normally used strain rate dependent elastic/plastic material models are not capable to simulate the mechanical behavior of thermoplastic materials depended on the state of stress. As part of a research project, a method to simulate the mechanical behavior of hybrid structures under impact conditions is developed at the IKV. For this purpose, a specimen for the measurement of mechanical properties dependet on the state of stress and a method for the strain rate depended characterization of thermoplastic materials were developed. In the second step impact testing is performed. A hybrid structure made from a metal sheet and a reinforcement structure of a Polybutylenterephthalat Polycarbonate blend is tested under impact conditions. The measured stress and strain rate depended material data are used to simulate the mechanical behavior of the hybrid structure under highly dynamic load with

  20. Pyrolysis of municipal plastic wastes: Influence of raw material composition.

    Science.gov (United States)

    López, A; de Marco, I; Caballero, B M; Laresgoiti, M F; Adrados, A

    2010-04-01

    The objective of this work is the study of pyrolysis as a feedstock recycling process, for valorizing the rejected streams that come from industrial plants, where packing and packaging wastes are classified and separated for their subsequent mechanical recycling. Four real samples collected from an industrial plant at four different times of the year, have been pyrolysed under nitrogen in a 3.5dm(3) autoclave at 500 degrees C for 30min. Pyrolysis liquids are a complex mixture of organic compounds containing valuable chemicals as styrene, ethyl-benzene, toluene, etc. Pyrolysis solids are composed of the inorganic material contained in the raw materials, as well as of some char formed in the pyrolysis process, and pyrolysis gases are mainly composed of hydrocarbons together with some CO and CO(2), and have very high gross calorific values (GCV). It has been proved by the authors that the composition of the raw material (paper, film, and metals contents) plays a significant role in the characteristics of pyrolysis products. High paper content yields water in the pyrolysis liquids, and CO and CO(2) in the gases, high PE film content gives rise to high viscosity liquids, and high metals content yields more aromatics in the liquid products, which may be attributed to the metals catalytic effect.

  1. Experimental and computational analysis of micromotions of an uncemented femoral knee implant using elastic and plastic bone material models.

    Science.gov (United States)

    Berahmani, Sanaz; Janssen, Dennis; Verdonschot, Nico

    2017-08-16

    It is essential to calculate micromotions at the bone-implant interface of an uncemented femoral total knee replacement (TKR) using a reliable computational model. In the current study, experimental measurements of micromotions were compared with predicted micromotions by Finite Element Analysis (FEA) using two bone material models: linear elastic and post-yield material behavior, while an actual range of interference fit was simulated. The primary aim was to investigate whether a plasticity model is essential in order to calculate realistic micromotions. Additionally, experimental bone damage at the interface was compared with the FEA simulated range. TKR surgical cuts were applied to five cadaveric femora and micro- and clinical CT- scans of these un-implanted specimens were made to extract geometrical and material properties, respectively. Micromotions at the interface were measured using digital image correlation. Cadaver-specific FEA models were created based on the experimental set-up. The average experimental micromotion of all specimens was 53.1±42.3µm (mean±standard deviation (SD)), which was significantly higher than the micromotions predicted by both models, using either the plastic or elastic material model (26.5±23.9µm and 10.1±10.1µm, respectively; p-valuematerial models). The difference between the two material models was also significant (p-value<0.001). The predicted damage had a magnitude and distribution which was comparable to the experimental bone damage. We conclude that, although the plastic model could not fully predict the micro motions, it is more suitable for pre-clinical assessment of a press-fit TKR implant than using an elastic bone model. Copyright © 2017 Elsevier Ltd. All rights reserved.

  2. Failure Orientation in Stretch Forming and Its Correlation with a Polycrystal Plasticity-Based Material Model for a Collection of Highly Formable Sheet Steels

    Science.gov (United States)

    An, Yuguo; Boterman, Romke; Atzema, Eisso; Abspoel, Michael; Scholting, Marc

    2016-07-01

    Robust design optimization techniques have been developed in recent years within the automotive industry with the aim of reducing scrap rates and improving process stability in sheet metal forming. These new techniques are able to take process variations and other sources of material scatter into account. Among the many material variables and inputs used, the yield criterion is an important aspect and this is used to describe the plastic behavior of sheet metals. To achieve a reliable output in an optimization study, the yield criterion selected must be representative of material response and scatter. However, simple material models that deviate from real material behavior are often used due to a lack of material data, which is usually a requirement when using more complex models. In the present research, a polycrystal plasticity-based CTFP model has been evaluated in stretch forming for a collection of highly formable sheet steel materials. The results demonstrate that the CTFP model can capture the yielding character and also detect the minor deviations presented by different coils. The stretching factor derived from the CTFP model, as opposed to the work hardening and ductility, has a dominant effect on failure for a collection of materials with similar mechanical properties. Results also indicate that plastic deformation causes texture evolution and, consequently, an evolving yield locus. Such changes in the yield locus during deformation have an effect on stretching and friction calibration in FE simulations.

  3. PLASTICITY OF SELECTED METALLIC MATERIALS IN DYNAMIC DEFORMATION CONDITIONS

    Directory of Open Access Journals (Sweden)

    Jacek PAWLICKI

    2014-06-01

    Full Text Available Characteristics of a modernized flywheel machine has been presented in the paper. The laboratory stand enables to perform dynamic tensile tests and impact bending with a linear velocity of the enforcing element in the range of 5÷40 m/s. A new data acquisition system, based on the tensometric sensors, allows for significant qualitative improvement of registered signals. Some preliminary dynamic forming tests were performed for the selected group of metallic materials. Subsequent microstructural examinations and identification of the fracture type enabled to describe a correlation between strain rate, strain and microstructure.

  4. Theoretical Development of an Orthotropic Elasto-Plastic Generalized Composite Material Model

    Science.gov (United States)

    Goldberg, Robert K.; Carney, Kelly S.; DuBois, Paul; Hoffarth, Canio; Harrington, Joseph; Subramanian, Rajan; Blankenhorn, Gunther

    2014-01-01

    The need for accurate material models to simulate the deformation, damage and failure of polymer matrix composites is becoming critical as these materials are gaining increased usage in the aerospace and automotive industries. While there are several composite material models currently available within LS-DYNA (Registered), there are several features that have been identified that could improve the predictive capability of a composite model. To address these needs, a combined plasticity and damage model suitable for use with both solid and shell elements is being developed and is being implemented into LS-DYNA as MAT_213. A key feature of the improved material model is the use of tabulated stress-strain data in a variety of coordinate directions to fully define the stress-strain response of the material. To date, the model development efforts have focused on creating the plasticity portion of the model. The Tsai-Wu composite failure model has been generalized and extended to a strain-hardening based orthotropic material model with a non-associative flow rule. The coefficients of the yield function, and the stresses to be used in both the yield function and the flow rule, are computed based on the input stress-strain curves using the effective plastic strain as the tracking variable. The coefficients in the flow rule are computed based on the obtained stress-strain data. The developed material model is suitable for implementation within LS-DYNA for use in analyzing the nonlinear response of polymer composites.

  5. Study on Impact Acoustic—Visual Sensor-Based Sorting of ELV Plastic Materials

    Science.gov (United States)

    Huang, Jiu; Tian, Chuyuan; Ren, Jingwei; Bian, Zhengfu

    2017-01-01

    This paper concentrates on a study of a novel multi-sensor aided method by using acoustic and visual sensors for detection, recognition and separation of End-of Life vehicles’ (ELVs) plastic materials, in order to optimize the recycling rate of automotive shredder residues (ASRs). Sensor-based sorting technologies have been utilized for material recycling for the last two decades. One of the problems still remaining results from black and dark dyed plastics which are very difficult to recognize using visual sensors. In this paper a new multi-sensor technology for black plastic recognition and sorting by using impact resonant acoustic emissions (AEs) and laser triangulation scanning was introduced. A pilot sorting system which consists of a 3-dimensional visual sensor and an acoustic sensor was also established; two kinds commonly used vehicle plastics, polypropylene (PP) and acrylonitrile-butadiene-styrene (ABS) and two kinds of modified vehicle plastics, polypropylene/ethylene-propylene-diene-monomer (PP-EPDM) and acrylonitrile-butadiene-styrene/polycarbonate (ABS-PC) were tested. In this study the geometrical features of tested plastic scraps were measured by the visual sensor, and their corresponding impact acoustic emission (AE) signals were acquired by the acoustic sensor. The signal processing and feature extraction of visual data as well as acoustic signals were realized by virtual instruments. Impact acoustic features were recognized by using FFT based power spectral density analysis. The results shows that the characteristics of the tested PP and ABS plastics were totally different, but similar to their respective modified materials. The probability of scrap material recognition rate, i.e., the theoretical sorting efficiency between PP and PP-EPDM, could reach about 50%, and between ABS and ABS-PC it could reach about 75% with diameters ranging from 14 mm to 23 mm, and with exclusion of abnormal impacts, the actual separation rates were 39.2% for PP, 41

  6. Rapid discrimination of plastic packaging materials using MIR spectroscopy coupled with independent components analysis (ICA)

    Energy Technology Data Exchange (ETDEWEB)

    Kassouf, Amine, E-mail: amine.kassouf@agroparistech.fr [ER004 “Lebanese Food Packaging”, Faculty of Sciences II, Lebanese University, 90656 Jdeideth El Matn, Fanar (Lebanon); INRA, UMR1145 Ingénierie Procédés Aliments, 1 Avenue des Olympiades, 91300 Massy (France); AgroParisTech, UMR1145 Ingénierie Procédés Aliments, 16 rue Claude Bernard, 75005 Paris (France); Maalouly, Jacqueline, E-mail: j_maalouly@hotmail.com [ER004 “Lebanese Food Packaging”, Faculty of Sciences II, Lebanese University, 90656 Jdeideth El Matn, Fanar (Lebanon); Rutledge, Douglas N., E-mail: douglas.rutledge@agroparistech.fr [INRA, UMR1145 Ingénierie Procédés Aliments, 1 Avenue des Olympiades, 91300 Massy (France); AgroParisTech, UMR1145 Ingénierie Procédés Aliments, 16 rue Claude Bernard, 75005 Paris (France); Chebib, Hanna, E-mail: hchebib@hotmail.com [ER004 “Lebanese Food Packaging”, Faculty of Sciences II, Lebanese University, 90656 Jdeideth El Matn, Fanar (Lebanon); Ducruet, Violette, E-mail: violette.ducruet@agroparistech.fr [INRA, UMR1145 Ingénierie Procédés Aliments, 1 Avenue des Olympiades, 91300 Massy (France); AgroParisTech, UMR1145 Ingénierie Procédés Aliments, 16 rue Claude Bernard, 75005 Paris (France)

    2014-11-15

    Highlights: • An innovative technique, MIR-ICA, was applied to plastic packaging separation. • This study was carried out on PE, PP, PS, PET and PLA plastic packaging materials. • ICA was applied to discriminate plastics and 100% separation rates were obtained. • Analyses performed on two spectrometers proved the reproducibility of the method. • MIR-ICA is a simple and fast technique allowing plastic identification/classification. - Abstract: Plastic packaging wastes increased considerably in recent decades, raising a major and serious public concern on political, economical and environmental levels. Dealing with this kind of problems is generally done by landfilling and energy recovery. However, these two methods are becoming more and more expensive, hazardous to the public health and the environment. Therefore, recycling is gaining worldwide consideration as a solution to decrease the growing volume of plastic packaging wastes and simultaneously reduce the consumption of oil required to produce virgin resin. Nevertheless, a major shortage is encountered in recycling which is related to the sorting of plastic wastes. In this paper, a feasibility study was performed in order to test the potential of an innovative approach combining mid infrared (MIR) spectroscopy with independent components analysis (ICA), as a simple and fast approach which could achieve high separation rates. This approach (MIR-ICA) gave 100% discrimination rates in the separation of all studied plastics: polyethylene terephthalate (PET), polyethylene (PE), polypropylene (PP), polystyrene (PS) and polylactide (PLA). In addition, some more specific discriminations were obtained separating plastic materials belonging to the same polymer family e.g. high density polyethylene (HDPE) from low density polyethylene (LDPE). High discrimination rates were obtained despite the heterogeneity among samples especially differences in colors, thicknesses and surface textures. The reproducibility of

  7. Mechanical and time-dependent behavior of wood-plastic composites subjected to tension and compression

    Science.gov (United States)

    Scott E. Hamel; John C. Hermanson; Steven M. Cramer

    2012-01-01

    The thermoplastics within wood—plastic composites (WPCs) are known to experience significant time-dependent deformation or creep. In some formulations, creep deformation can be twice as much as the initial quasi-static strain in as little as 4 days. While extensive work has been done on the creep behavior of pure polymers, little information is available on the...

  8. PARAMETRIC VARIATIONAL PRINCIPLE BASED ELASTIC-PLASTIC ANALYSIS OF HETEROGENEOUS MATERIALS WITH VORONOI FINITE ELEMENT METHOD

    Institute of Scientific and Technical Information of China (English)

    ZHANG Hong-wu; WANG Hui

    2006-01-01

    The Voronoi cell finite element method (VCFEM) is adopted to overcome the limitations of the classic displacement based finite element method in the numerical simulation of heterogeneous materials. The parametric variational principle and quadratic programming method are developed for elastic-plastic Voronoi finite element analysis of two-dimensional problems. Finite element formulations are derived and a standard quadratic programming model is deduced from the elastic-plastic equations. Influence of microscopic heterogeneities on the overall mechanical response of heterogeneous materials is studied in detail. The overall properties of heterogeneous materials depend mostly on the size, shape and distribution of the material phases of the microstructure. Numerical examples are presented to demonstrate the validity and effectiveness of the method developed.

  9. Sensory and motor components of reproductive behavior : pathways and plasticity

    NARCIS (Netherlands)

    Holstege, Gert; Van der Horst, Veronique G.J.M.

    Reproductive behavior in most mammalian species consists of a highly stereotyped pattern of movements, is elicited by specific sensory stimuli and is sex steroid dependent. The present paper describes a concept of the pathways in the midbrain, brainstem and spinal cord which control the receptive

  10. Plastic phase change material and articles made therefrom

    Science.gov (United States)

    Abhari, Ramin

    2016-04-19

    The present invention generally relates to a method for manufacturing phase change material (PCM) pellets. The method includes providing a melt composition, including paraffin and a polymer. The paraffin has a melt point of between about 10.degree. C. and about 50.degree. C., and more preferably between about 18.degree. C. and about 28.degree. C. In one embodiment, the melt composition includes various additives, such as a flame retardant. The method further includes forming the melt composition into PCM pellets. The method further may include the step of cooling the melt to increase the melt viscosity before pelletizing. Further, PCM compounds are provided having an organic PCM and a polymer. Methods are provided to convert the PCM compounds into various form-stable PCMs. A method of coating the PCMs is included to provide PCMs with substantially no paraffin seepage and with ignition resistance properties.

  11. Plastic phase change material and articles made therefrom

    Energy Technology Data Exchange (ETDEWEB)

    Abhari, Ramin

    2016-04-19

    The present invention generally relates to a method for manufacturing phase change material (PCM) pellets. The method includes providing a melt composition, including paraffin and a polymer. The paraffin has a melt point of between about 10.degree. C. and about 50.degree. C., and more preferably between about 18.degree. C. and about 28.degree. C. In one embodiment, the melt composition includes various additives, such as a flame retardant. The method further includes forming the melt composition into PCM pellets. The method further may include the step of cooling the melt to increase the melt viscosity before pelletizing. Further, PCM compounds are provided having an organic PCM and a polymer. Methods are provided to convert the PCM compounds into various form-stable PCMs. A method of coating the PCMs is included to provide PCMs with substantially no paraffin seepage and with ignition resistance properties.

  12. DEVELOPMENT OF PLASTICITY MODEL USING NON ASSOCIATED FLOW RULE FOR HCP MATERIALS INCLUDING ZIRCONIUM FOR NUCLEAR APPLICATIONS

    Energy Technology Data Exchange (ETDEWEB)

    Michael V. Glazoff; Jeong-Whan Yoon

    2013-08-01

    In this report (prepared in collaboration with Prof. Jeong Whan Yoon, Deakin University, Melbourne, Australia) a research effort was made to develop a non associated flow rule for zirconium. Since Zr is a hexagonally close packed (hcp) material, it is impossible to describe its plastic response under arbitrary loading conditions with any associated flow rule (e.g. von Mises). As a result of strong tension compression asymmetry of the yield stress and anisotropy, zirconium displays plastic behavior that requires a more sophisticated approach. Consequently, a new general asymmetric yield function has been developed which accommodates mathematically the four directional anisotropies along 0 degrees, 45 degrees, 90 degrees, and biaxial, under tension and compression. Stress anisotropy has been completely decoupled from the r value by using non associated flow plasticity, where yield function and plastic potential have been treated separately to take care of stress and r value directionalities, respectively. This theoretical development has been verified using Zr alloys at room temperature as an example as these materials have very strong SD (Strength Differential) effect. The proposed yield function reasonably well models the evolution of yield surfaces for a zirconium clock rolled plate during in plane and through thickness compression. It has been found that this function can predict both tension and compression asymmetry mathematically without any numerical tolerance and shows the significant improvement compared to any reported functions. Finally, in the end of the report, a program of further research is outlined aimed at constructing tensorial relationships for the temperature and fluence dependent creep surfaces for Zr, Zircaloy 2, and Zircaloy 4.

  13. Characterization of a new plastic scintillation material and comparison with liquid BC-501A scintillator

    OpenAIRE

    Poleshchuk, Oleksii

    2015-01-01

    In this work the capability of various scintillation materials to discriminate gamma rays and neutrons were studied. Also such basic properties of scintillators as light emission spectrum and light output were determined. The studied materials were BC-501A liquid scintillator and a plastic scintillator provided by CEA. An experimental setup consisting of detector shielding, analog and digital electronics and data acquisition system was built to study the neutron-gamma discrimination propertie...

  14. Roles of texture and latent hardening on plastic anisotropy of face-centered-cubic materials during multi-axial loading

    Science.gov (United States)

    Pham, M. S.; Creuziger, A.; Iadicola, M.; Rollett, A. D.

    2017-02-01

    This study investigates the joint impact of preferred texture and latent hardening on the plastic anisotropy of face centered cubic (FCC) materials. The main result is that both aspects have significant impact on the anisotropy, but the two can either counteract each other or synergistically reinforce each other to maximize anisotropy. Preferred texture results in significant anisotropy in plastic yielding. However, the latent hardening significantly alters the texture-induced anisotropy. In addition, one latent hardening type can cancel out the anisotropy of another type. Consequently, if all dislocation-based latent hardening types are included at the same level as the self-hardening, the result might not reveal the complexity of plastic anisotropy. The present study of the synergistic influence of detailed latent hardening and texture presented helps provide new insights into the complex anisotropic behavior of FCC materials during multi-axial forming. the stress at which the material initially yields is not a function of material orientation with respect to the frame of the test (i.e., isotropic yielding); there exists a multi-axial yield locus that is described by a single value of stress that corresponds to yield in uniaxial tension (i.e., stress equivalency); on hardening, the multi-axial yield locus expands by the same amount in every direction in the π-plane, which is the plane that has its normal parallel to [111] in the deviatoric stress space (i.e., isotropic hardening); there is an associated flow rule, i.e., the strain increment is normal to the yield locus.

  15. Prediction and classification of the degradation state of plastic materials used in modern and contemporary art

    Science.gov (United States)

    Manfredi, M.; Barberis, E.; Marengo, E.

    2017-01-01

    Today, artworks partially or completely made of plastic materials can be found in almost all international museums and collections. The deterioration of these objects is now becoming evident mainly because these synthetic materials are not designed for a long life and the characterization of their state of conservation can help curators and conservators. In this research we investigated the applicability of a portable attenuated total reflection (ATR) infrared spectrometer for the non-invasive characterization and for monitoring the degradation of plastics used in modern and contemporary art. Several polypropylene and polycarbonate samples were artificially aged in solar box, simulating about 200 years of museum light exposure, and they were monitored with the portable ATR, creating an infrared library of the conservation state of plastics. Through the use of chemometric techniques like principal component analysis-linear discriminant analysis and partial least square—discriminant analysis, we built a robust degradation model of each material that can be used to predict and classify the degradation state of artworks and to identify the priority of intervention in the museum collections. Portable ATR coupled to multivariate statistics can be employed for taking care of plastic artworks as it is non-invasive, the analysis is very fast and it can be performed directly in situ.

  16. Plastic deformation behavior of Fe–Co–B–Si–Nb–Cr bulk metallic glasses under nanoindentation

    Energy Technology Data Exchange (ETDEWEB)

    Kim, J.T.; Hong, S.H.; Lee, C.H. [HMC, Faculty of Nanotechnology and Advanced Materials Engineering, Sejong University, 98 Gunja-dong, Gwangjin-gu, Seoul 143-747 (Korea, Republic of); Park, J.M., E-mail: jinman_park@hotmail.com [Materials Research Center, Samsung Advanced Institute of Technology (SAIT), San 14-1, Nongseo-dong, Giheung-gu, Yongin-si, Gyeonggi-do 446-712 (Korea, Republic of); Kim, T.W.; Lee, W.H. [HMC, Faculty of Nanotechnology and Advanced Materials Engineering, Sejong University, 98 Gunja-dong, Gwangjin-gu, Seoul 143-747 (Korea, Republic of); Yim, H.I. [Department of Physics, Sookmyung Women’s University, Hyochangwongil 52, Yongsan-ku, Seoul 140-742 (Korea, Republic of); Kim, K.B., E-mail: kbkim@sejong.ac.kr [HMC, Faculty of Nanotechnology and Advanced Materials Engineering, Sejong University, 98 Gunja-dong, Gwangjin-gu, Seoul 143-747 (Korea, Republic of)

    2014-02-25

    Highlights: • Additional Cr modulation of atomic structure of Fe-Co-B-Si-Nb BMGs. • An amount of free volume characterized by a combination of nanoindentation and AFM. • Free volume determined by height measurement of AFM after nanoindentation. -- Abstract: In this work, we investigate the effect of Cr addition on thermal properties and indentation behavior of Fe{sub 52}Co{sub 20−x}B{sub 20}Si{sub 4}Nb{sub 4}Cr{sub x} alloys with x = 0, 1, 3 and 5 at.%, respectively. Among all studied alloys, the Fe{sub 52}Co{sub 17}B{sub 20}Si{sub 4}Nb{sub 4}Cr{sub 3} bulk metallic glass (BMG) exhibits the highest thermal stability with large supercooled liquid region of 40 K and the pronounced plastic deformation features which is serrated flow (pop-in event) and significant pile-up of materials around indents. This demonstrates that the appropriate addition of Cr in Fe-based BMG can induce the internal atomic structure modulation and promote the mechanical softening, which are discussed in terms of free volume concept.

  17. Effect of plastic deformation on the acoustoelastic response of some materials

    Science.gov (United States)

    Daami, T.; Touratier, M.; Castex, L.

    1987-12-01

    Acoustoelastic birefringence is measured with the acoustic polarimeter by transmitting ultrasonic shear waves at two perpendicular polarizations through the thickness of several uniaxial test specimens. The results are available for the following materials: SAE 1010 and SAE 4118 steel, pure titanium, 2024 aluminum and 60-40 brass, but are only presented here for SAE 4118 steel and pure titanium. The uniaxial test specimens have been subjected to plastic deformation followed by complete unloading. It is shown that the assumption that the plastic flow leading to the residual-stress state does not change the acoustic response of the material, does not hold for all materials and that further characterization development is required for general quantitative residual-stress determination.

  18. The use of plasticizing additives based on recycled raw materials in the petrochemical rubber mixtures

    Directory of Open Access Journals (Sweden)

    Z. S. Shashok

    2016-01-01

    Full Text Available At present, the development of alternative products for elastomers based on recycling petrochemical raw materials is a new trend of the rubber industry progress. Petrochemical raw materials include spent lubricants and motor oils are among such recycling products. In this context, the influence of the products of recycling waste engine oil (DVCH and RA in comparison with industrial oil (I-20 on the technological properties of filled elastomeric compositions was investigated. The elastomeric compositions were based on poly isoprene and divinyl rubbers. The plasticizing components were manufactured by IOOO “DVCH-Menedzhment”. They are mixture of hydro-carbons, C16–C20 and differ from each other in the content of linear and branched paraffin. Plastic-elastic properties of rubber compounds on the shear disk viscometer MV2000 in accordance with GOST 10722–76 was carried out. Kinetics of vulcanization on the rheometer ODR2000 according to GOST 12535–84 was defined. It is shown that the introduction of RA test plasticizing component provides a significant effect on Mooney viscosity, as compared to elastomeric compositions containing a plasticizer and I-20 and plasticizing additive DVCH. It revealed that the administration of all components in the studied plasticizing elastomer compositions based on a combination poly isoprene and divinyl rubbers has no significant effect on the rate of relaxation of stress of rubber compounds. It is found that elastomeric compositions containing as additives investigated processing waste oil products (DVCH and RA are characterized by a slightly smaller value of time to reach an optimal degree of vulcanization.

  19. Behaviour and Environment - A Behavioral Study of no Use of Plastic Bags' Intention

    Directory of Open Access Journals (Sweden)

    Eliane Bragança de Matos

    2013-06-01

    Full Text Available The perception of the environmental impact of current consumption patterns and the increasing centrality of this discourse in international environmentalism’s mainstream bring new perspectives and arguments concerning the consumerism of contemporary Western societies. From this perspective, the central question of this project was: “What is the intention of not using plastic bags?” Using as a theoretical reference the Planned Behavior Theory, which seeks to understand and predict human behavior in a general way from a reduced set of antecedent variables, we developed an intersectional survey consisting of 226 interviews. Data were processed by equations modeling and treated in Amos 16.0 software. The measurement model considered the mental constructions forming TCP. It was possible to identify as a major contribution of this study that the perceived behavioral control is the most influential factor on the intended not use of plastic bags, hindering the adoption of the behavior of not using plastic bags. Perhaps the fact that it is a settled habit, which involves several routine actions, such as the habit of going to the grocery store and have to plan in advance to take the alternative shopping bag or cart for packaging purchased products, or to count on ecological alternatives offered by commercial establishments, is a major and determining impediment for behavioral change.

  20. Corrosion resistance of plastic materials and method for improvement on quality. Plastic zairyo no taishokusei to hinshitsu kojo taisaku

    Energy Technology Data Exchange (ETDEWEB)

    Li, W. (Tokyo Institute of Technology, Tokyo (Japan). Faculty of Engineering)

    1991-09-20

    The plastic materials are described mainly in corrosiveness as follows: Definition of corrosion for the high-molecular materials. Obtainment of stress relaxation curve, by utilizing the photoelasticity, of the polyvinyl chloride resin to be evaluated in corrosiveness. Corrosion morphology (observation result by the optical microscope) in case that the PP (polypropylene resin) reformed by SBS (styrene butadiene styrene) is corroded by HNO{sub 3} or H{sub 2}SO{sub 4}, and chemical reaction to mainly cause that corrosion. Utilization of differential scanning calorimetry to set the PP and that reformed by NBR (nitrile butadiene rubber) in welding temperature. Dyeing of NBR-reformed phenol resin by OsO{sub 4} and observation on the thus dyed structure (where there exist both the contents). Observational investigation, by applying the AE (acoustic emission) technology, on the heightening in toughness due to reforming the phenol resin by NBR and degradation due to the corrosion of NBR-reformed phenol resin. 10 refs., 15 figs.

  1. Contrasting glass and plastic material requirements for reflective and refractive CPV solar systems

    Science.gov (United States)

    Horne, Steve; Krevor, David

    2012-10-01

    Concentrator PhotoVoltaic (CPV) solar energy systems concentrate the sun 500 - 1,000 times or more, in order to take economic advantage of the most advanced and efficient solar cells. The two prevalent system architectures use either reflective glass optics - such as based on a Cassegrain telescope design - or a refractive plastic system - either an acrylic or silicone-on-glass Fresnel lens - for concentration. Both systems have their advantages in areas of performance and durability. Both system designs manufacture their optics by low-cost processes that are unavailable to the other material system. These contrasts are reviewed. The refractive system embodies a simpler optical concept, requiring a single Fresnel lens rather than two concentrating mirrors. However, the reflective, glass system uses the greater design sophistication to provide a greater acceptance angle, which yields tolerance benefits in both manufacture and installation; and also provides faster optics without suffering the spectral aberrations of the refractive systems. Both glass and plastics are low-cost commodity materials. The long-term durability of optical glass is more firmly established than for optical plastics. And light transmission through optical plastics is attenuated by absorbance in both the UV and IR regions, in regions where such light is harvested by efficient multi-junction solar cells.

  2. Energy and raw material saving through recycling of plastics materials extracted from urban waste. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Michaux, J.

    The study is divided into 3 parts: Technical feasibility study, economic feasibility study, study of a factory handling 2,400 tons/year of plastics waste, and technico-economic feasibility study and market research, with an analysis of energy savings.

  3. Elastic-plastic behavior of a semicircular frame being pressed against a rigid plane

    Institute of Scientific and Technical Information of China (English)

    X. W. Zhang; J. L. Yang; T. X. Yu

    2008-01-01

    As a simplified structural model, a semicircular frame is used to study the crashworthiness behavior of an aircraft fuselage. The quasi-static large elastic-plastic deformation of a semicircular frame in the process of its being pressed against a rigid ground is analyzed. First, based on the linear elastic assumption, the quasi-static large deformation contact process of the frame can be divided into three phases, i.e., point contact, line contact and post-buckling. By means of a shooting method, the relations between the displacement and contact force as well as the distribution of bending moment in the three phases are obtained. Then, by assuming an elastic, perfectly-plastic moment-curvature relationship for the semi-circular frame, the contact process is analyzed in detail to reveal the plastic collapse mechanism, the traveling of plastic hinge and the force-displacement relationship. In order to verify the analysis, a preliminary experiment was conducted, in which two types of half rings with clamped ends were pressed by a rigid plate. In addition, a numerical simulation is also conducted by employing ABAQUS to analyze both rectangular cross-sectional beam and I-beam. Finally, the theoretical predictions are compared with the experimental results and numerical solutions, showing that the elastic-plastic analysis can predict the contact process very well.

  4. Why New Spinal Cord Plasticity Does Not Disrupt Old Motor Behaviors.

    Science.gov (United States)

    Chen, Yi; Chen, Lu; Wang, Yu; Chen, Xiang Yang; Wolpaw, Jonathan R

    2017-08-23

    When new motor learning changes the spinal cord, old behaviors are not impaired; their key features are preserved by additional compensatory plasticity. To explore the mechanisms responsible for this compensatory plasticity, we transected the spinal dorsal ascending tract before or after female rats acquired a new behavior-operantly conditioned increase or decrease in the right soleus H-reflex-and examined an old behavior-locomotion. Neither spinal dorsal ascending tract transection nor H-reflex conditioning alone impaired locomotion. Nevertheless, when spinal dorsal ascending tract transection and H-reflex conditioning were combined, the rats developed a limp and a tilted posture that correlated in direction and magnitude with the H-reflex change. When the right H-reflex was increased by conditioning, the right step lasted longer than the left and the right hip was higher than the left; when the right H-reflex was decreased by conditioning, the opposite occurred. These results indicate that ascending sensory input guides the compensatory plasticity that normally prevents the plasticity underlying H-reflex change from impairing locomotion. They support the concept of the state of the spinal cord as a negotiated equilibrium that reflects the concurrent influences of all the behaviors in an individual's repertoire; and they support the new therapeutic strategies this concept introduces.SIGNIFICANCE STATEMENT The spinal cord provides a reliable final common pathway for motor behaviors throughout life. Until recently, its reliability was explained by the assumption that it is hardwired; but it is now clear that the spinal cord changes continually as new behaviors are acquired. Nevertheless, old behaviors are preserved. This study shows that their preservation depends on sensory feedback from the spinal cord to the brain: if feedback is removed, the acquisition of a new behavior may disrupt an old behavior. In sum, when a new behavior changes the spinal cord, sensory

  5. Water equivalence of some plastic-water phantom materials for clinical proton beam dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Al-Sulaiti, L., E-mail: l.al-sulaiti@surrey.ac.uk [Physics Department, University of Surrey, Guildford (United Kingdom); Radiation Dosimetry Team, National Physical Laboratory, Teddington (United Kingdom); Shipley, D.; Thomas, R. [Radiation Dosimetry Team, National Physical Laboratory, Teddington (United Kingdom); Owen, P. [Physics Department, University of Surrey, Guildford (United Kingdom); Radiation Dosimetry Team, National Physical Laboratory, Teddington (United Kingdom); Kacperek, A. [Douglas Cyclotron, Clatterbridge Centre for Oncology, Wirral (United Kingdom); Regan, P.H. [Physics Department, University of Surrey, Guildford (United Kingdom); Palmans, H. [Radiation Dosimetry Team, National Physical Laboratory, Teddington (United Kingdom)

    2012-07-15

    Plastic-water phantom materials are not exactly water equivalent since they have a different elemental composition and different interaction cross sections for protons than water. Several studies of the water equivalence of plastic-water phantom materials have been reported for photon and electron beams, but none for clinical proton beams. In proton beams, the difference between non-elastic nuclear interactions in plastic-water phantom materials compared to those in water should be considered. In this work, the water equivalence of Plastic Water{sup Registered-Sign} (PW){sup 1}, Plastic Water{sup Registered-Sign} Diagnostic Therapy (PWDT){sup 1} and solid water (WT1){sup 2} phantoms was studied for clinical proton energies of 60 MeV and 200 MeV. This was done by evaluating the fluence correction factor at equivalent depths; first with respect to water and then with respect to graphite by experiment and Monte Carlo (MC) simulations using FLUKA. MC simulations showed that the fluence correction with respect to water was less than 0.5% up to the entire penetration depth of the protons at 60 MeV and less than 1% at 200 MeV up to 20 cm depth for PWDT, PW and WT1. With respect to graphite the fluence correction was about 0.5% for 60 MeV and about 4% for 200 MeV. The experimental results for modulated and un-modulated 60 MeV proton beams showed good agreement with the MC simulated fluence correction factors with respect to graphite deviating less than 1% from unity for the three plastic-water phantoms. - Highlights: Black-Right-Pointing-Pointer We study plastic-water in clinical proton beams by experiment and Monte Carlo. Black-Right-Pointing-Pointer We obtain fluence correction factors for water and graphite. Black-Right-Pointing-Pointer The correction factor for water was close to 1 at 60 MeV and <0.990 at 200 MeV. Black-Right-Pointing-Pointer The correction factor for graphite was {approx}0.5% at 60 MeV and up to 4% at 200 MeV.

  6. Atomic-scale analysis of plastic deformation in thin-film forms of electronic materials

    Science.gov (United States)

    Kolluri, Kedarnath

    Nanometer-scale-thick films of metals and semiconductor heterostructures are used increasingly in modern technologies, from microelectronics to various areas of nanofabrication. Processing of such ultrathin-film materials generates structural defects, including voids and cracks, and may induce structural transformations. Furthermore, the mechanical behavior of these small-volume structures is very different from that of bulk materials. Improvement of the reliability, functionality, and performance of nano-scale devices requires a fundamental understanding of the atomistic mechanisms that govern the thin-film response to mechanical loading in order to establish links between the films' structural evolution and their mechanical behavior. Toward this end, a significant part of this study is focused on the analysis of atomic-scale mechanisms of plastic deformation in freestanding, ultrathin films of face-centered cubic (fcc) copper (Cu) that are subjected to biaxial tensile strain. The analysis is based on large-scale molecular-dynamics simulations. Elementary mechanisms of dislocation nucleation are studied and several problems involving the structural evolution of the thin films due to the glide of and interactions between dislocations are addressed. These problems include void nucleation, martensitic transformation, and the role of stacking faults in facilitating dislocation depletion in ultrathin films and other small-volume structures of fcc metals. Void nucleation is analyzed as a mechanism of strain relaxation in Cu thin films. The glide of multiple dislocations causes shearing of atomic planes and leads to formation of surface pits, while vacancies are generated due to the glide motion of jogged dislocations. Coalescence of vacancy clusters with surface pits leads to formation of voids. In addition, the phase transformation of fcc Cu films to hexagonal-close packed (hcp) ones is studied. The resulting martensite phase nucleates at the film's free surface and

  7. Rapid discrimination of plastic packaging materials using MIR spectroscopy coupled with independent components analysis (ICA).

    Science.gov (United States)

    Kassouf, Amine; Maalouly, Jacqueline; Rutledge, Douglas N; Chebib, Hanna; Ducruet, Violette

    2014-11-01

    Plastic packaging wastes increased considerably in recent decades, raising a major and serious public concern on political, economical and environmental levels. Dealing with this kind of problems is generally done by landfilling and energy recovery. However, these two methods are becoming more and more expensive, hazardous to the public health and the environment. Therefore, recycling is gaining worldwide consideration as a solution to decrease the growing volume of plastic packaging wastes and simultaneously reduce the consumption of oil required to produce virgin resin. Nevertheless, a major shortage is encountered in recycling which is related to the sorting of plastic wastes. In this paper, a feasibility study was performed in order to test the potential of an innovative approach combining mid infrared (MIR) spectroscopy with independent components analysis (ICA), as a simple and fast approach which could achieve high separation rates. This approach (MIR-ICA) gave 100% discrimination rates in the separation of all studied plastics: polyethylene terephthalate (PET), polyethylene (PE), polypropylene (PP), polystyrene (PS) and polylactide (PLA). In addition, some more specific discriminations were obtained separating plastic materials belonging to the same polymer family e.g. high density polyethylene (HDPE) from low density polyethylene (LDPE). High discrimination rates were obtained despite the heterogeneity among samples especially differences in colors, thicknesses and surface textures. The reproducibility of the proposed approach was also tested using two spectrometers with considerable differences in their sensitivities. Discrimination rates were not affected proving that the developed approach could be extrapolated to different spectrometers. MIR combined with ICA is a promising tool for plastic waste separation that can help improve performance in this field; however further technological improvements and developments are required before it can be applied

  8. Feasibility Study of Sensor Aided Impact Acoustic Sorting of Plastic Materials from End-of-Life Vehicles (ELVs)

    OpenAIRE

    Jiu Huang; Zhengfu Bian; Shaogang Lei

    2015-01-01

    The purpose of this feasibility research was to study a novel sensor based separation method for recycling of plastic materials from end-of-life vehicles (ELVs) by using eigen-frequency response of impact acoustic emission. In this research three kinds of commonly used plastics, polypropylene (PP), acrylonitrile-butadiene-styrene (ABS), and styrene-maleic-anhydride (SMA) sampled from end-of-life vehicles, were researched. Almost all the crushed plastic scraps had a flake structure, theoretica...

  9. Earthquake statistics inferred from plastic events in soft-glassy materials

    CERN Document Server

    Benzi, Roberto; Trampert, Jeannot

    2016-01-01

    We propose a new approach for generating synthetic earthquake catalogues based on the physics of soft glasses. The continuum approach produces yield-stress materials based on Lattice-Boltzmann simulations. We show that, if the material is stimulated below yield stress, plastic events occur, which have strong similarities with seismic events. Based on a suitable definition of displacement in the continuum, we show that the plastic events obey a Gutenberg-Richter law with exponents similar to those for real earthquakes. We further find that average acceleration, energy release, stress drop and recurrence times scale with the same exponent. The approach is fully self-consistent and all quantities can be calculated at all scales without the need of ad hoc friction or statistical laws. We therefore suggest that our approach may lead to new insight into understanding of the physics connecting the micro and macro scale of earthquakes.

  10. WATER RESISTANCE OF WOOD - PLASTIC COMPOSITES MADE FROM WASTE MATERIALS RESULTED IN THE FURNITURE MANUFACTURING PROCESS

    OpenAIRE

    Camelia COŞEREANU; Dumitru LICA; Ioan CURTU; Mariana-Domnica STANCIU

    2014-01-01

    The purpose of this paper is to present innovative wood-plastic composites made from waste materials such as ABS (acrylonitrile butadiene styrene) and wood shavings resulted in the furniture manufacturing process. From previous investigations (with regard to physical integrity and compactness of the panels), only mixtures ranging from a ratio of 100% ABS: 0% shavings to 80% ABS: 20% shavings were selected for water resistance testing. Swelling in thickness and water absorption for...

  11. Migration of nanoparticles from plastic packaging materials containing carbon black into foodstuffs.

    Science.gov (United States)

    Bott, Johannes; Störmer, Angela; Franz, Roland

    2014-01-01

    Carbon black was investigated to assess and quantify the possibility that nanoparticles might migrate out of plastic materials used in the food packaging industry. Two types of carbon black were incorporated in low-density polyethylene (LDPE) and polystyrene (PS) at 2.5% and 5.0% loading (w/w), and then subjected to migration studies. The samples were exposed to different food simulants according to European Union Plastics Regulation 10/2011, simulating long-term storage with aqueous and fatty foodstuffs. Asymmetric flow field-flow fractionation (AF4) coupled to a multi-angle laser light-scattering (MALLS) detector was used to separate, characterise and quantify the potential release of nanoparticles. The AF4 method was successful in differentiating carbon black from other matrix components, such as extracted polymer chains, in the migration solution. At a detection limit of 12 µg kg⁻¹, carbon black did not migrate from the packaging material into food simulants. The experimental findings are in agreement with theoretical considerations based on migration modelling. From both the experimental findings and theoretical considerations, it can be concluded that carbon black does not migrate into food once it is incorporated into a plastics food contact material.

  12. ANALYSIS OF BIODEGRABILITY OF DEGRADABLE/BIODEGRADABLE PLASTIC MATERIAL IN CONTROLLED COMPOSTING ENVIRONMENT

    Directory of Open Access Journals (Sweden)

    Dana Adamcová

    2016-09-01

    Full Text Available We have obtained eight degradable/biodegradable materials based on starch (certified compostable, sample 4–7, HDPE mixed with totally degradable plastic additive (TDPA, sample 2 and polyethylene with the addition of pro-oxidant additive (d2w, sample 1. Composition of sample 3 has not been reported. The materials have been tested as to the rate and character of their degradability/biodegradability in controlled composting conditions. Experiment explored also the effect of degradation/biodegradation of plastic bags on compost quality. The material of the original samples was subjected to assessment using the Nicolet 6700 FT-IR spectrometer, the outcome thereof was obtaining infrared spectra of the samples. For further specification the original samples were tested using the thermogravimetrical analysis. The texture of the foils at different stages of degradation is presented in the Scanning Electron Microscope (SEM photographs. Plastic bags certified as compostable have degraded in laboratory conditions and their degradation had no impact on the quality and features of compost. Selected samples (4, 6 showed significant erosion on surface when subjected to the SEM analysis. Samples labeled (by their producers as 100% degradable (samples 1, 2, 3 did not show any visual signs of degradation and the process of degradation had no impact on the quality and features of compost. Only one of the samples (sample 1 showed certain erosion of surface when submitted for the SEM analysis.

  13. Development of methods for predicting large crack growth in elastic-plastic work-hardening materials in fully plastic conditions

    Science.gov (United States)

    Ford, Hugh; Turner, C. E.; Fenner, R. T.; Curr, R. M.; Ivankovic, A.

    1995-01-01

    The objects of the first, exploratory, stage of the project were listed as: (1) to make a detailed and critical review of the Boundary Element method as already published and with regard to elastic-plastic fracture mechanics, to assess its potential for handling present concepts in two-dimensional and three-dimensional cases. To this was subsequently added the Finite Volume method and certain aspects of the Finite Element method for comparative purposes; (2) to assess the further steps needed to apply the methods so far developed to the general field, covering a practical range of geometries, work hardening materials, and composites: to consider their application under higher temperature conditions; (3) to re-assess the present stage of development of the energy dissipation rate, crack tip opening angle and J-integral models in relation to the possibilities of producing a unified technology with the previous two items; and (4) to report on the feasibility and promise of this combined approach and, if appropriate, make recommendations for the second stage aimed at developing a generalized crack growth technology for its application to real-life problems.

  14. Selected Plastics Wear Resistance to Bonded Abrasive Particles Compared to Some Ferrous Materials

    Directory of Open Access Journals (Sweden)

    Milan Brožek

    2015-01-01

    Full Text Available Plastics are macromolecular materials without we cannot imagine any branch of human activity with. Plastics have unique properties, often very different from metals. At the choice of the concrete plastic for the concrete application it is necessary to evaluate its mechanical, physical, chemical and technological properties. In last years producers offer also plastics for production of parts exposed to different types of wear. In the contribution the results of wear resistance studying of 10 types of plastics (PTFE, PVC, POM-C, PC, PETP, PEEK, PA66, PP, PA6E and PE-UHMW of one producer are published and compared with test results of four different Fe alloys (grey iron, structural steel, cast steel wear resistant and high-speed steel. The laboratory tests were carried out using the pin-on-disk machine with abrasive cloth (according to ČSN 01 5084, when the abrasive clothes of three different grits (240, 120 and 60 were used. It corresponds to the average abrasive grain sizes of 44.5 µm, 115.5 µm and 275 µm. During the test the test sample was pressed to the abrasive cloth by the pressure of 0.1 MPa. The wear intensity was assessed by the volume, weight and length losses of tested samples. The technical-economical evaluation was the part of the carried out tests. It was univocally proved that at the intensive abrasive wear using the abrasive cloth the best results shows the High-Speed Steel HSS Poldi Radeco 19 810 according to ČSN 41 9810, although its price is relatively high. Other tested Fe alloys, namely grey iron according to ČSN 42 2415, structural steel 11 373 according to ČSN 41 1373 and wear resistant cast steel VPH 6 showed also very favourable properties at the material low price. In comparison with Fe alloys the wear of all plastics was considerably higher and the plastics were considerably more expensive.

  15. Water plasticization of extruded material made from meat and bone meal and sodium caseinate.

    Science.gov (United States)

    Garcia, Rafael A; Onwulata, Charles I; Ashby, Richard D

    2004-06-16

    Meat and bone meal (MBM) is a high protein agricultural commodity that currently has few applications other than as an animal feed. Unmodified MBM has poor functional properties, due to its low solubility. Our results from pilot plant trials demonstrate that MBM can be extrusion-processed along with sodium caseinate to produce a useful plastic material. We developed this material for use as a dog chew toy. For this application, elastic modulus (stiffness) is a key characteristic. Our results detail the relationship between ambient relative humidity and equilibrium moisture content (MC) in the material. The influence of MC on the glass transition temperature and elastic modulus reflects the plasticization of this material by water. On the basis of a comparison to a commercially available dog chew, the range of stiffness achievable with our material, 0.25-2.50 GPa, encompasses the values appropriate for a dog chew. Our results show that a particular desired stiffness can be maintained by applying an edible moisture barrier to the surface of the material.

  16. Biodegradability of biodegradable/degradable plastic materials under aerobic and anaerobic conditions.

    Science.gov (United States)

    Mohee, R; Unmar, G D; Mudhoo, A; Khadoo, P

    2008-01-01

    A study was conducted on two types of plastic materials, Mater-Bi Novamont (MB) and Environmental Product Inc. (EPI), to assess their biodegradability under aerobic and anaerobic conditions. For aerobic conditions, organic fractions of municipal solid wastes were composted. For the anaerobic process, anaerobic inoculum from a wastewater treatment plant was used. Cellulose filter papers (CFP) were used as a positive control for both mediums. The composting process was monitored in terms of temperature, moisture and volatile solids and the biodegradation of the samples were monitored in terms of mass loss. Monitoring results showed a biodegradation of 27.1% on a dry basis for MB plastic within a period of 72 days of composting. Biodegradability under an anaerobic environment was monitored in terms of biogas production. A cumulative methane gas production of 245 ml was obtained for MB, which showed good degradation as compared to CFP (246.8 ml). However, EPI plastic showed a cumulative methane value of 7.6 ml for a period of 32 days, which was close to the blank (4.0 ml). The EPI plastic did not biodegrade under either condition. The cumulative carbon dioxide evolution after 32 days was as follows: CFP 4.406 cm3, MB 2.198 cm3 and EPI 1.328 cm3. The cumulative level of CO2 varying with time fitted sigmoid type curves with R2 values of 0.996, 0.996 and 0.995 for CFP, MB and EPI, respectively.

  17. [The application of the nanostructured bioplastic material for the plastic reconstruction of perforations in the nasal septum].

    Science.gov (United States)

    Grigor'eva, M V; Akimov, A V; Bagautdinov, A A

    2014-01-01

    The objective of the present work was to estimate the effectiveness of the application of the nanostructured bioplastic material for the plastic reconstruction of perforations in the nasal septum. A total of 80 patients were recruited for the study. Half of them underwent plastic reconstruction of perforations in the nasal septum with the application of the nanostructured bioplastic material. Forty patients were treated using no biotransplants. The functional state of nasal cavity mucosa was evaluated before and after surgery. It is concluded that the nanostructured bioplastic material used in the present study ensures efficacious reconstruction of nasal septum integrity after plastic correction of septal perforations.

  18. Analysis of the elastic-plastic indentation properties of materials with varying ratio of hardness to Young's modulus

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The elastic-plastic indentation properties of materials with varying ratio of hardness to Young's modulus (H/E) were analyzed with the finite element method. And the indentation stress fields of materials with varying ratio H/E on the surface were studied by the experiment. The results show that the penetration depth, contact radius, plastic pileup and the degree of elastic recovery depend strongly on the ratio H/E. Moreover, graphs were established to describe the relationship between the elastic-plastic indentation parameters and H/E. The established graphs can be used to predict the H/E of materials when compared with experimental data.

  19. Measurement and material modeling of biaxial work-hardening behavior for pure titanium sheet

    Science.gov (United States)

    Sumita, Takeshi; Kuwabara, Toshihiko

    2013-12-01

    Biaxial tensile tests of a commercial pure titanium sheet (JIS ♯1) were performed using a servo-controlled multiaxial tube expansion testing machine developed by one of the authors [Kuwabara, T. and Sugawara, F., Multiaxial tube expansion test method for measurement of sheet metal deformation behavior under biaxial tension for a large strain range, Int. J. Plasticity, 45 (2013), 103-118]. Tubular specimens with an inner diameter of 54 mm were fabricated by roller bending and TIG welding the as-received test material with a thickness of 0.5 mm. Several linear stress paths in the first quadrant of the stress space were applied to the tubular specimens to measure the contours of plastic work and the directions of the plastic strain rates for an equivalent plastic strain range of 0.05 ≤ ɛ0p ≤ 0.30. It was found that the shapes of the work contours significantly changed with an increase in ɛ0p and that the Yld2000-2d yield function could reproduce the differential work hardening behavior of the test material by changing the material parameters and the exponent as functions of ɛ0p.

  20. Nutrient mediation of behavioral plasticity and resource allocation in a xylem-feeding leafhopper.

    Science.gov (United States)

    Brodbeck, Brent V; Andersen, Peter C; Mizell, Russell F

    2011-01-01

    Phenotypic plasticity may be critical for nutrient-limited organisms that allocate ingested nutrients to the competing demands of reproduction and survivorship. Leafhoppers that feed on xylem fluid allow assessment of plasticity in response to the constant selective pressure of nutritional inadequacy. We examined feeding behavior (host selection and consumption rates) and nutrient allocation (fecundity, change in body mass and composition) of the xylem fluid-feeding leafhopper Homalodisca vitripennis (Hemiptera:Cicadellidae) on ten genotypes of related Prunus germplasm when adults first seasonally appear, and later during population peaks, to examine the effects of genotypes and season on plasticity of life history and behavioral traits. Behavior and resource allocation to life history traits were both mediated by xylem nutrients, although nutrients impacting behavior differed from those mediating life history. Host selection and consumption varied with genotype between June and July, yet behavior consistently reflected concentrations of dietary glutamine. Resource allocations also increased linearly with nutrient concentrations, but were best correlated to ingested essential amino acids rather than glutamine. Body mass and composition were highly correlated to dietary essential amino acids in June; 6 weeks later, fecundity was instead proportional to essential amino acids. The discrepancy in nutrients which impact behavior versus those mediating life history may explain the weak preference-performance linkage documented for many insects. The demarcation in allocating resources to biomass in June to fecundity in July suggests increased allocation to reproduction during periods of nutrient stress as predicted by the theory of optimal resource allocation; other contributing biotic and abiotic factors are also discussed.

  1. Hardening in Two-Phase Materials. II. Plastic Strain and Mean Stress Hardening Rate

    DEFF Research Database (Denmark)

    Lilholt, Hans

    1977-01-01

    The strain parameters which are relevant in a tensile experiment, are analysed and related to the geometry of deformation and to the mean stress of two-phase materials. The hardening rate of the mean stress with respect to plastic strain is found to be useful in comparison between experiments and...... and theories, and it allows theories to be probed over a range of strains. Previous experiments on the fibre-reinforced material of copper-tungsten are analysed in relation to the geometry of deformation....

  2. Multiaxial mechanical behavior of biological materials.

    Science.gov (United States)

    Sacks, Michael S; Sun, Wei

    2003-01-01

    For native and engineered biological tissues, there exist many physiological, surgical, and medical device applications where multiaxial material characterization and modeling is required. Because biological tissues and many biocompatible elastomers are incompressible, planar biaxial testing allows for a two-dimensional (2-D) stress-state that can be used to fully characterize their three-dimensional (3-D) mechanical properties. Biological tissues exhibit complex mechanical behaviors not easily accounted for in classic elastomeric constitutive models. Accounting for these behaviors by careful experimental evaluation and formulation of constitutive models continues to be a challenging area in biomechanical modeling and simulation. The focus of this review is to describe the application of multiaxial testing techniques to soft tissues and their relation to modern biomechanical constitutive theories.

  3. Influence Of The Plastic Material Behaviour On The Prediction Of Forming Limits

    Science.gov (United States)

    Vegter, H.; ten Horn, C. H. L. J.; van den Boogaard, A. H.

    2007-05-01

    Prediction of the onset of necking is of large importance in reliability of forming simulation in present automotive industry. Advanced material models require accurate descriptions of the plastic material behaviour including the effect of strain rate. The usual approach for identifying the forming limits in industry is the comparison of a calculated strain map (major against minor strain) with a measured forming limit curve. This approach does not take into account the influence of strain path changes. Prediction of forming limit curves with classical material models can already demonstrate that the forming limits are influenced by this strain path change effect. Including the effect of strain rate on the plastic material behaviour has a strong influence in prediction of onset of instability. Neglecting this effect leads to underestimation of forming capacity of the material in stretch forming parts in particular. The shape of the yield locus will influence the predicted forming limit curves in the region from plane strain to bi-axial. Damage controlled failure will become more important using (advanced) high strength steels. This will affect the stress strain curve at high deformation grades. The work hardening is not only controlled by dislocation interaction, but also by void growth and possible presence of micro-cracks at the interface between the hard en soft phases.

  4. Thermal behavior and kinetic study for catalytic co-pyrolysis of biomass with plastics.

    Science.gov (United States)

    Zhang, Xuesong; Lei, Hanwu; Zhu, Lei; Zhu, Xiaolu; Qian, Moriko; Yadavalli, Gayatri; Wu, Joan; Chen, Shulin

    2016-11-01

    The present study aims to investigate the thermal decomposition behaviors and kinetics of biomass (cellulose/Douglas fir sawdust) and plastics (LDPE) in a non-catalytic and catalytic co-pyrolysis over ZSM-5 catalyst by using a thermogravimetric analyzer (TGA). It was found that there was a positive synergistic interaction between biomass and plastics according to the difference of weight loss (ΔW), which could decrease the formation of solid residue at the end of the experiment. The first order reaction model well fitted for both non-catalytic and catalytic co-pyrolysis of biomass with plastics. The activation energy (E) of Cellulose-LDPE-Catalyst and DF-LDPE-Catalyst are only 89.51 and 54.51kJ/mol, respectively. The kinetics analysis showed that adding catalyst doesn't change the decomposition mechanism. As a result, the kinetic study on catalytic co-pyrolysis of biomass with plastics was suggested that the catalytic co-pyrolysis is a promising technique that can significantly reduce the energy input.

  5. Marketing and materiality in the popular music transmedia of Gorillaz’ Plastic Beach

    Directory of Open Access Journals (Sweden)

    Alex JEFFERY

    2017-07-01

    Full Text Available The entertainment complexes of narrative transmedia contain few instances based in popular music. However, those that exist provide intriguing case studies, highly distinct from those based in film and television. The most fully realized of these, Gorillaz’ Plastic Beach (2010, is rich in visual media typical of popular music culture, including sleeve art, animated music videos. The tangible materiality foregrounded in these visuals stems from the main ecological theme of the album: the disposability of plastic waste. Using methods of analysis of the original texts, and a survey of the networked fan practices that respond to them, the essay theorizes that the material and haptic invitation in these visuals is at odds with the diminishing presence of physical consumables within popular music culture. It then argues that fans enter into this gap with their own creative practices, making and playing with hand-made or customized objects inspired by Plastic Beach, activating unexploited, marketing potential within the album. Although current applications of this research are limited due to the low frequency of popular music transmedia case studies, it points the way forward to theoretically more successful marketing strategies in the future.

  6. The Effects of Weathering on Mechanical Properties of Glass Fiber Reinforced Plastics (Grp Materials

    Directory of Open Access Journals (Sweden)

    H. Abdullah

    2012-08-01

    Full Text Available Glass fiber reinforced plastics composite is extensively used as a structural material for pools, oil pipes and tanks because it has good corrosion resistance properties.  The effects of weathering on the mechanical properties of glass fiber reinforced plastics (GRP in the Sultanate of Oman have been studied.  The tensile and three point bend specimens were exposed to outdoor conditions (open atmosphere in sunlight and tested for various intervals of time.  It was observed that as the exposure time to sunlight, ultraviolet radiation and dust increases the mechanical properties of GRP materials decrease.  The effects of relative humidity (%RH on the mechanical properties were also studied. It was found that as the relative humidity increased in the atmosphere during the exposure time, the tensile strength, flexural strength and modulus of elasticity are lowered. This work has revealed that the decrease in the mechanical properties of GRP under weathering conditions is subjected to atmospheric conditions such as humidity, temperature, ultraviolet radiation and pollutant.Key Words: Weathering, Glass-Fiber Reinforced Plastics, Degradation

  7. Role of NMDA Receptors in Dopamine Neurons for Plasticity and Addictive Behaviors

    Science.gov (United States)

    Zweifel, Larry S.; Argilli, Emanuela; Bonci, Antonello; Palmiter, Richard D.

    2008-01-01

    Summary A single exposure to drugs of abuse produces an NMDA receptor (NMDAR)-dependent long-term potentiation (LTP) of AMPA receptor (AMPAR) currents in DA neurons; however, the importance of LTP for various aspects of drug addiction is unclear. To test the role of NMDAR-dependent plasticity in addictive behavior, we genetically inactivated functional NMDAR signaling exclusively in DA neurons (KO mice). Inactivation of NMDARs results in increased AMPAR-mediated transmission that is indistinguishable from the increases associated with a single cocaine exposure, yet locomotor responses to multiple drugs of abuse were unaltered in the KO mice. The initial phase of locomotor sensitization to cocaine is intact; however, the delayed sensitization that occurs with prolonged cocaine withdrawal did not occur. Conditioned behavioral responses for cocaine-testing environment were also absent in the KO mice. These findings provide evidence for a role of NMDAR signaling in DA neurons for specific behavioral modifications associated with drug seeking behaviors. PMID:18701073

  8. HOW DO DEGRADABLE/BIODEGRADABLE PLASTIC MATERIALS DECOMPOSE IN HOME COMPOSTING ENVIRONMENT?

    Directory of Open Access Journals (Sweden)

    Magdalena Vaverková

    2014-10-01

    Full Text Available This paper provides information about biodegradability of polymeric (biodegradable/degradable materials advertised as 100%-degradable or certified as compostable, which may be a part of biodegradable waste, in home composting conditions. It describes an experiment that took place in home wooden compost bins and contained 9 samples that are commonly available in retail chains in the Czech Republic and Poland. The experiment lasted for the period of 12 weeks. Based on the results thereof it can be concluded that polyethylene samples with additive (samples 2, 4, 7 have not decomposed, their color has not changed and that no degradation or physical changes have occurred. Samples 1, 3 and 5 certified as compostable have not decomposed. Sample 6 exhibited the highest decomposition rate. Samples 8, 9 (tableware exhibited high degree of decomposition. The main conclusion from this study is that degradable/biodegradable plastics or plastics certified as compostable are not suitable for home composting.

  9. Characteristics of wood-fiber plastic composites made of recycled materials.

    Science.gov (United States)

    Ashori, Alireza; Nourbakhsh, Amir

    2009-04-01

    This study investigates the feasibility of using recycled high density polyethylene (rHDPE), polypropylene (rPP) and old newspaper (rONP) fiber to manufacture experimental composite panels. The panels were made through air-forming and hot press. The effects of the fiber and coupling agent concentration on tensile, flexural, internal bond properties and water absorption and thickness swelling of wood-fiber plastic composites were studied. The use of maleated polypropylene as coupling agent improved the compatibility between the fiber and both plastic matrices and mechanical properties of the resultant composites compared well with those of non-coupled ones. Based on the findings in this work, it appears that recycled materials can be used to manufacture value-added panels without having any significant adverse influence on board properties. It was also found that composites with rHDPE provided moderately superior properties, compared with rPP samples.

  10. Numerical modelling of reinforced concrete beams with fracture-plastic material

    Directory of Open Access Journals (Sweden)

    O. Sucharda

    2014-10-01

    Full Text Available This paper describes the use of models of fracture-plastic materials for reinforced concrete in numerical modelling of beams made from reinforced concrete. The purpose of the paper is to use of a model of concrete for modelling of a behaviour of reinforced concrete beams which have been tested at the University of Toronto within re-examination of classic concrete beam tests. The original tests were performed by Bresler- Scordelis. A stochastic modelling based on LHS (Latin Hypercube Sampling has been performed for the reinforced concrete beam. An objective of the modelling is to evaluate the total bearing capacity of the reinforced concrete beams depending on distribution of input data. The beams from the studied set have longitudinal reinforcement only. The beams do not have any shear reinforcement. The software used for the fracture-plastic model of the reinforced concrete is the ATENA.

  11. WATER RESISTANCE OF WOOD - PLASTIC COMPOSITES MADE FROM WASTE MATERIALS RESULTED IN THE FURNITURE MANUFACTURING PROCESS

    Directory of Open Access Journals (Sweden)

    Camelia COŞEREANU

    2014-12-01

    Full Text Available The purpose of this paper is to present innovative wood-plastic composites made from waste materials such as ABS (acrylonitrile butadiene styrene and wood shavings resulted in the furniture manufacturing process. From previous investigations (with regard to physical integrity and compactness of the panels, only mixtures ranging from a ratio of 100% ABS: 0% shavings to 80% ABS: 20% shavings were selected for water resistance testing. Swelling in thickness and water absorption for 2h and 24h were determined for the proposed wood-plastic composites. The results have shown that only a participation of up to 10% of wood shavings in the tested panels conducted to a good performance

  12. GREEN PLASTIC: A NEW PLASTIC FOR PACKAGING

    OpenAIRE

    Mr. Pankaj Kumar*, Sonia

    2016-01-01

    This paper gives a brief idea about a new type of plastic called as bio-plastic or green plastic. Plastic is used as a packaging material for various products, but this plastic is made up of non renewable raw materials. There are various disadvantages of using conventional plastic like littering, CO2 production, non-degradable in nature etc. To overcome these problems a new type of plastic is discovered called bio-plastic or green plastic. Bio-plastic is made from renewable resources and also...

  13. Associating Specific Materials with Topological Insulation Behavior

    Science.gov (United States)

    Zhang, Xiuwen

    2014-03-01

    The first-principles (a) total-energy/stability calculations combined with (b) electronic structure calculations of band inversion, spin-polarization and topological invariants (Z2) has led to the design and prediction of specific materials that are topological insulators in this study. We classify bulk materials into four types of band-inversion behaviors (TI-1, TI-2, BI-3, BI-4), based on the number of band inversions and their distributions on various time reversal invariant k points. Depending on the inversion type in bulk, the corresponding surface states have different protections e.g., protected by time reversal symmetry (in TI-1 materials), spatial symmetry (in TI-2), or not protected (in BI-3, BI-4). Subject 1 Discovery of new TI by screening materials for a Z2 metric: Such high-throughput search in the framework of Inverse Design methodology predicts a few previously undocumented materials that are TI-1 in their ground state crystal structure. We also predict dozens of materials that are TI-1 however in structures that are not ground states (e.g. perovskite structure of II-Bi-O3). Subject 2 Design Principle to increase the gap of TI-1 materials: In HgTe-like cubic topological materials, the insulating gap is zero since the spin-orbit splitting is positive and so a 4-fold half-filled p-like band is near the Fermi level. By design of hybridization of d-orbitals into the p-like bands, one can create negative spin-orbit splitting and so a finite insulating gap. Subject 3 Unconventional spin textures of TI surface states: Despite the fact that one of our predicted TI-1 KBaBi has inversion symmetry in the bulk-a fact that that would preclude bulk spin polarization-we find a Dresselhaus-like spin texture with non-helical spin texture. This originates from the local spin polarization, anchored on the atomic sites with inversion asymmetric point groups, that is compensated due to global inversion symmetry in bulk. In collaboration with: Jun-Wei Luo, Qihang Liu

  14. Cocaine activates Rac1 to control structural and behavioral plasticity in caudate putamen.

    Science.gov (United States)

    Li, Juan; Zhang, Lei; Chen, Zhenzhong; Xie, Minjuan; Huang, Lu; Xue, Jinhua; Liu, Yutong; Liu, Nuyun; Guo, Fukun; Zheng, Yi; Kong, Jiming; Zhang, Lin; Zhang, Lu

    2015-03-01

    Repeated exposure to cocaine was previously found to cause sensitized behavioral responses and structural remodeling on medium spiny neurons of the nucleus accumbens (NAc) and caudate putamen (CPu). Rac1 has emerged as a key integrator of environmental cues that regulates dendritic cytoskeletons. In this study, we investigated the role of Rac1 in cocaine-induced dendritic and behavioral plasticity in the CPu. We found that Rac1 activation was reduced in the NAc but increased in the CPu following repeated cocaine treatment. Inhibition of Rac1 activity by a Rac1-specific inhibitor NSC23766, overexpression of a dominant negative mutant of Rac1 (T17N-Rac1) or local knockout of Rac1 attenuated the cocaine-induced increase in dendrites and spine density in the CPu, whereas overexpression of a constitutively active Rac1 exert the opposite effect. Moreover, NSC23766 reversed the increased number of asymmetric spine synapses in the CPu following chronic cocaine exposure. Downregulation of Rac1 activity likewise attenuates behavioral reward responses to cocaine exposure, with activation of Rac1 producing the opposite effect. Thus, Rac1 signaling is differentially regulated in the NAc and CPu after repeated cocaine treatment, and induction of Rac1 activation in the CPu is important for cocaine exposure-induced dendritic remodeling and behavioral plasticity.

  15. PLASTIC DEFORMATION BEHAVIOR OF ELECTROFORMED COPPER LINER OF SHAPED CHARGE AT DIFFERENT STRAIN RATES

    Institute of Scientific and Technical Information of China (English)

    H.Y. Gao; W.H. Tian; A.L. Fan; Q. Sun

    2003-01-01

    The paper deals with different plastic deformation behavior of electroformed copperliner of shaped charge, deformed at high strain rate (about 1×107 s-1) and normalstrain rate (4×10-4 s-1). The crystallographic orientation distribution of grains inrecovered slugs which had undergone high-strain-rate plastic deformation during ex-plosive detonation was investigated by electron backscattering Kikuchi pattern tech-nique. Cellular structures formed by tangled dislocations and sub-grain boundariesconsisting of dislocation arrays were detected in the recovered slugs. Some twins andslip dislocations were observed in specimen deformed at normal strain rate. It wasfound that dynamic recovery and recrystallization take place during high-strain-ratedeformation due to the temperature rising, whereas the conventional slip mechanismoperates during deformation at normal strain rate.

  16. PLASTIC DEFORMATION BEHAVIOR OF ELECTROFORMED COPPER LINER OF SHAPED CHARGE AT DIFFERENT STRAIN RATES

    Institute of Scientific and Technical Information of China (English)

    H.Y.Gao; Q.Sun

    2003-01-01

    The paper deals with different plastic deformation behavior of electroformed copper liner of shaped charge,depormed at high strain rate(about 1×107s-1) and normal strain rate (4×10-4s-1).The crystallographic orientation distribution of grains in recovered slugs which had undergone high-strain-rate plastic deformation during ex-plosive detonation was investigated by electron backscattering Kikuchi pattern tech-nique.Cellualar structures formed by tangled disocations and sub-grain boundaries consisting of dislocation arrays were detected in the recovered slugs.Some twins and slip dislocations were observed in specimen deformed at normal strain rate.It was found that dynamic recovery and recrystallization take place during high-strain-rate deformation due to the temperature rising,whereas the conventional slip mechanism operates during deformation at normal strain rate.

  17. Behavioral plasticity, behavioral syndromes and animal personality in crustacean decapods: An imperfect map is better than no map

    Institute of Scientific and Technical Information of China (English)

    Francesca GHERARDI; Laura AQUILONI; Elena TRICARICO

    2012-01-01

    Despite their key role as model organisms in many behavioral studies,crustacean decapods have been only slightly touched upon by the recent surge of scientific interest in animal personality.Only seven articles investigated the issue in a handful of species among hermit crabs,crabs,and crayfish.Obviously,a limited number of publications does not mean that personality is rare in decapods.On the contrary,few studies might be the result of a form of reluctance by behavioral ecologists to deal with such a phenomenon in these and other invertebrates.This reluctance contrasts with the enthusiasm shown in tackling the behavioral plasticity issue.Here we discuss the possible theoretical and methodological difficulties raised by applying the animal personality perspective to decapods and analyze implications of personality studies for their ecology,conservation,and welfare.By highlighting gaps in knowledge and directions of future research,our intention is to increase scientific emphasis on the issue.

  18. Molecular surface structural changes of plasticized PVC materials after plasma treatment.

    Science.gov (United States)

    Zhang, Xiaoxian; Zhang, Chi; Hankett, Jeanne M; Chen, Zhan

    2013-03-26

    In this research, a variety of analytical techniques including sum frequency generation vibrational spectroscopy (SFG), coherent anti-Stokes Raman spectroscopy (CARS), and X-ray photoelectron spectroscopy (XPS) have been employed to investigate the surface and bulk structures of phthalate plasticized poly(vinyl chloride) (PVC) at the molecular level. Two types of phthalate molecules with different chain lengths, diethyl phthalate (DEP) and dibutyl phthalate (DBP), mixed with PVC in various weight ratios were examined to verify their different surface and bulk behaviors. The effects of oxygen and argon plasma treatment on PVC/DBP and PVC/DEP hybrid films were investigated on both the surface and bulk of films using SFG and CARS to evaluate the different plasticizer migration processes. Without plasma treatment, SFG results indicated that more plasticizers segregate to the surface at higher plasticizer bulk concentrations. SFG studies also demonstrated the presence of phthalates on the surface even at very low bulk concentration (5 wt %). Additionally, the results gathered from SFG, CARS, and XPS experiments suggested that the PVC/DEP system was unstable, and DEP molecules could leach out from the PVC under low vacuum after several minutes. In contrast, the PVC/DBP system was more stable; the migration process of DBP out of PVC could be effectively suppressed after oxygen plasma treatment. XPS results indicated the increase of C═O/C-O groups and decrease of C-Cl functionalities on the polymer surface after oxygen plasma treatment. The XPS results also suggested that exposure to argon plasma induced chemical bond breaking and formation of cross-linking or unsaturated groups with chain scission on the surface. Finally, our results indicate the potential risk of using DEP molecules in PVC since DEP can easily leach out from the polymeric bulk.

  19. Methods for an investigation of the effect of material components on the mechanical characteristics of glass-fiber-reinforced plastics

    Science.gov (United States)

    Willax, H. O.

    1980-01-01

    The materials used in the production of glass reinforced plastics are discussed. Specific emphasis is given to matrix polyester materials, the reinforcing glass materials, and aspects of specimen preparation. Various methods of investigation are described, giving attention to optical impregnation and wetting measurements and the gravimetric determination of the angle of contact. Deformation measurements and approaches utilizing a piezoelectric device are also considered.

  20. Repeated research of biodegradability of plastics materials in real composting conditions

    Directory of Open Access Journals (Sweden)

    Dana Adamcová

    2013-01-01

    Full Text Available The aim of this paper was to verify information obtained by repeated research provide in 2011 and 2012 in real composting conditions and check information about biodegradability of plastics bags in real composting conditions. In both cases samples were placed into frames and inserted into one clamp within the compost pile to investigate the biodegradation. The plastics bags were obtained from chain stores in the Czech Republic and Poland. The shopping bags were made of HDPE with the TDPA additive (sample 2, PP with an addition of pro-oxidants (d2w (sample 1, 3 and materials certified as compostable (starch, polycaprolactone (sample 4, 5, 6, 7. Control sample (cellulose filtering paper, sample 8 was to check the potential of biological decomposition in the tested environment. At the end of the 15-week experimental period it was found that the polyethylene samples with the additive (sample 1, 2, 3 had not been decomposed, their colour had not changed and that no degradation neither physical changes had occurred (did not biodegrade. Samples certified as compostable (sample 4, 5, 6, 7 were decomposed. The results at the municipal compost facility demonstrate that the compostable plastics biodegrade and polyethylene samples with the additive did not biodegrade in compost.

  1. Greenhouse gas emissions from the treatment of household plastic containers and packaging: replacement with biomass-based materials.

    Science.gov (United States)

    Yano, Junya; Hirai, Yasuhiro; Sakai, Shin-ichi; Tsubota, Jun

    2014-04-01

    The purpose of this study was to quantify the life-cycle greenhouse gas (GHG) emissions reduction that could be achieved by replacement of fossil-derived materials with biodegradable, biomass-based materials for household plastic containers and packaging, considering a variety of their treatment options. The biomass-based materials were 100% polylactide or a combination of polybutylene succinate adipate and polylactide. A scenario analysis was conducted considering alternative recycling methods. Five scenarios were considered: two for existing fossil-derived materials (the current approach in Japan) and the three for biomass-based materials. Production and waste disposal of 1 m(3) of plastic containers and packaging from households was defined as the functional unit. The results showed that replacement of fossil-derived materials with biomass-based materials could reduce life-cycle GHG emissions by 14-20%. Source separation and recycling should be promoted. When the separate collection ratio reached 100%, replacement with biomass-based materials could potentially reduce GHG emissions by 31.9%. Food containers are a priority for replacement, because they alone could reduce GHG emissions by 10%. A recycling system for biomass-based plastics must be carefully designed, considering aspects such as the transition period from fossil-derived plastics to biomass-based plastics.

  2. Computational material design for Q&P steels with plastic instability theory

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, Guang; Choi, Kyoo Sil; Hu, Xiaohua; Sun, Xin

    2017-07-17

    In this paper, the deformation limits of Quenching and Partitioning (Q&P) steels are examined with the plastic instability theory. For this purpose, the constituent phase properties of various Q&P steels were first experimentally obtained, and used to estimate the overall tensile stress-strain curves based on the simple rule of mixture (ROM) with the iso-strain and iso-stress assumptions. Plastic instability theory was then applied to the obtained overall stress-strain curves in order to estimate the deformation limits of the Q&P steels. A parametric study was also performed to examine the effects of various material parameters on the deformation limits of Q&P steels. Computational material design was subsequently carried out based on the information obtained from the parametric study. The results show that the plastic instability theory with iso-stress-based stress-strain curve may be used to provide the lower bound estimate of the uniform elongation (UE) for the various Q&P steels considered. The results also indicate that higher austenite stability/volume fractions, less strength difference between the primary phases, higher hardening exponents of the constituent phases are generally beneficial for the performance improvement of Q&P steels, and that various material parameters may be concurrently adjusted in a cohesive way in order to improve the performance of Q&P steel. The information from this study may be used to devise new heat treatment parameters and alloying elements to produce Q&P steels with the improved performance.

  3. The importance of material structure in the laser cutting of glass fiber reinforced plastic composites

    Energy Technology Data Exchange (ETDEWEB)

    Caprino, G. (Univ. di Napoli (Italy). Dipt. di Ingegneria dei Materiali e della Produzione); Tagliaferri, V. (Univ. di Salerno (Italy). Istituto di Ingegneria Meccanica); Covelli, L. (IMU-Consiglio Nazionale delle Ricerche, Milano (Italy))

    1995-01-01

    A previously proposed micromechanical formula, aiming to predict the vaporization energy Q[sub v] of composite materials as a function of fiber and matrix properties and fiber volume ratio, was assessed. The experimental data, obtained on glass fiber reinforced plastic panels with different fiber contents cut by a medium power CO[sub 2] cw laser, were treated according to a procedure previously suggested, in order to evaluate Q[sub v]. An excellent agreement was found between experimental and theoretical Q[sub v] values. Theory was then used to predict the response to laser cutting of a composite material with a fiber content varying along the thickness. The theoretical predictions indicated that, in this case, the interpretation of the experimental results may be misleading, bringing to errors in the evaluation of the material thermal properties, or in the prediction of the kerf depth. Some experimental data were obtained, confirming the theoretical findings.

  4. Behavioral plasticity mediates asymmetric competition between invasive wasps and native ants.

    Science.gov (United States)

    Grangier, Julien; Lester, Philip J

    2012-03-01

    One of the most successful invasive species is the common wasp, Vespula vulgaris. We recently reported how foragers of this species have adopted previously unknown interference behavior when competing for food with native ants. Picking their opponents up in their mandibles, flying backward and dropping them some distance away from the disputed resource, wasps were shown to efficiently deal with a yet aggressive competitor and to modulate this behavior according to circumstances. Here we further discuss the nature and functioning of this unusual strategy. We first highlight the questions this interaction raises regarding the competitive advantages offered by asymmetries in body size and flight ability. Then, we argue that this study system illustrates the important role of behavioral plasticity in biological invasions; not only in the success of invaders but also in the ability of native species to coexist with these invaders.

  5. Use of Advanced Plastic Materials in Nigeria: Performance Assessment of Expanded Polystyrene Building Technology System

    Directory of Open Access Journals (Sweden)

    Anthony Nkem Ede (PhD

    2016-08-01

    Full Text Available The provision of affordable residential houses for the masses in the developing nations has been a mirage over the years and the future does not portend good as the cost of adopting conventional concrete material technologies is escalating while so many environmental issues like climate change are being raised in the recent times.To circumvent this poor housing provision trend, some innovative construction materials and technologies are being introduced to facilitate unique modular designs, reduction of labour, decline in the depletion of exhaustible materials,savings of time and fund. One of such materials is the expanded polystyrene. The introduction of advanced plastic materials and in particular the expanded polystyrene building technologies in the Nigerian constructionindustry will be a very useful and brilliant initiative that will aid the reduction of cost of construction and facilitate access to affordable houses for the masses.This researchaims at studying the applications of this innovative plastic material in the Nigerian building industry with special regard to the performance perception by the clients and the end users. A building estate where expanded polystyrene building technology has been predominantly used in Abuja is considered as a case study. Questionnaires were distributed among clients and residents of the building estate and statistical tools were used to analyse the data collected. Great satisfaction verified among the clients and residents and the high ranking performance confirmed for recyclability, reliability, versatility and moisture resistance of EPS building products all herald a great future for the applications of this advanced building products in the Nigerian building industry.

  6. A discrete thermodynamic approach for modeling anisotropic coupled plasticity-damage behavior in geomaterials

    Science.gov (United States)

    Zhu, Qi-zhi; Shao, Jian-fu; Kondo, Djimedo

    2008-04-01

    In the present Note, we present a discrete thermodynamic approach for modeling coupled anisotropic plastic flow and damage evolution in geomaterials. The basic idea is to extend the widely-used isotropic coupled elastoplastic damage formulation to the case with induced anisotropy using a discrete approach. The total plastic strain is considered as the consequence of frictional sliding in weak sliding planes randomly distributed in the elastic solid matrix. The effective elastic tensor of damaged material is determined using damage variable associated with each family of weak sliding planes. An example of application is shown for a typical semi-brittle rock. To cite this article: Q.-Z. Zhu et al., C. R. Mecanique 336 (2008).

  7. A J integral based method to measure fracture resistance and cohesive laws in materials exhibiting large scale plasticity

    DEFF Research Database (Denmark)

    Sørensen, Bent F.; Goutianos, Stergios

    2014-01-01

    A method is developed to extract the fracture resistance and mode I cohesive law of nonlinear elastic-plastic materials using a Double Cantilever Beam (DCB) sandwich specimen loaded with pure bending moments. The method is based on the J integral which is valid for materials having a non-linear s......A method is developed to extract the fracture resistance and mode I cohesive law of nonlinear elastic-plastic materials using a Double Cantilever Beam (DCB) sandwich specimen loaded with pure bending moments. The method is based on the J integral which is valid for materials having a non...

  8. Short-Term Plasticity of a Thalamocortical Pathway Dynamically Modulated by Behavioral State

    Science.gov (United States)

    Castro-Alamancos, Manuel A.; Connors, Barry W.

    1996-04-01

    The neocortex receives information about the environment and the rest of the brain through pathways from the thalamus. These pathways have frequency-dependent properties that can strongly influence their effect on the neocortex. In 1943 Morison and Dempsey described "augmenting responses," a form of short-term plasticity in some thalamocortical pathways that is triggered by 8- to 15-hertz activation. Results from anesthetized rats showed that the augmenting response is initiated by pyramidal cells in layer V. The augmenting response was also observed in awake, unrestrained animals and was found to be dynamically modulated by their behavioral state.

  9. Uterotrophic and Hershberger assays for endocrine disruption properties of plastic food contact materials polypropylene (PP) and polyethylene terephthalate (PET).

    Science.gov (United States)

    Chung, Bu Young; Kyung, Minji; Lim, Seong Kwang; Choi, Seul Min; Lim, Duck Soo; Kwack, Seung Jun; Kim, Hyung Sik; Lee, Byung-Mu

    2013-01-01

    Plasticizers or plastic materials such as phthalates, bisphenol-A (BPA), and styrene are widely used in the plastic industry and are suspected endocrine-disrupting chemicals (EDC). Although plastic materials such as polypropylene (PP) and polyethylene terephthalate (PET) are not EDC and are considered to be safe, their potential properties as EDC have not been fully investigated. In this study, plastic samples eluted from plastic food containers (PP or PET) were investigated in Sprague-Dawley rats using Hershberger and uterotrophic assays. In the Hershberger assay, 6-wk-old castrated male rats were orally treated for 10 consecutive days with plastic effluent at 3 different doses (5 ml/kg) or vehicle control (corn oil, 1 ml/100 g) to determine the presence of both anti-androgenic and androgenic effects. Testosterone (0.4 mg/ml/kg) was subcutaneously administered for androgenic evaluation as a positive control, whereas testosterone (0.4 mg/ml/kg) and flutamide (3 mg/kg/day) were administered to a positive control group for anti-androgenic evaluation. The presence of any anti-androgenic or androgenic activities of plastic effluent was not detected. Sex accessory tissues such as ventral prostate or seminal vesicle showed no significant differences in weight between treated and control groups. For the uterotrophic assay, immature female rats were treated with plastic effluent at three different doses (5 ml/kg), with vehicle control (corn oil, 1 ml/100 g), or with ethinyl estradiol (3 μg/kg/d) for 3 d. There were no significant differences between test and control groups in vagina or uterine weight. Data suggest that effluents from plastic food containers do not appear to produce significant adverse effects according to Hershberger and uterotrophic assays.

  10. Insights into the Transcriptional Architecture of Behavioral Plasticity in the Honey Bee Apis mellifera

    KAUST Repository

    Khamis, Abdullah M.

    2015-06-15

    Honey bee colonies exhibit an age-related division of labor, with worker bees performing discrete sets of behaviors throughout their lifespan. These behavioral states are associated with distinct brain transcriptomic states, yet little is known about the regulatory mechanisms governing them. We used CAGEscan (a variant of the Cap Analysis of Gene Expression technique) for the first time to characterize the promoter regions of differentially expressed brain genes during two behavioral states (brood care (aka “nursing”) and foraging) and identified transcription factors (TFs) that may govern their expression. More than half of the differentially expressed TFs were associated with motifs enriched in the promoter regions of differentially expressed genes (DEGs), suggesting they are regulators of behavioral state. Strikingly, five TFs (nf-kb, egr, pax6, hairy, and clockwork orange) were predicted to co-regulate nearly half of the genes that were upregulated in foragers. Finally, differences in alternative TSS usage between nurses and foragers were detected upstream of 646 genes, whose functional analysis revealed enrichment for Gene Ontology terms associated with neural function and plasticity. This demonstrates for the first time that alternative TSSs are associated with stable differences in behavior, suggesting they may play a role in organizing behavioral state.

  11. Effects of acceleration rate on Rayleigh-Taylor instability in elastic-plastic materials

    Science.gov (United States)

    Banerjee, Arindam; Polavarapu, Rinosh

    2016-11-01

    The effect of acceleration rate in the elastic-plastic transition stage of Rayleigh-Taylor instability in an accelerated non-Newtonian material is investigated experimentally using a rotating wheel experiment. A non-Newtonian material (mayonnaise) was accelerated at different rates by varying the angular acceleration of a rotating wheel and growth patterns of single mode perturbations with different combinations of amplitude and wavelength were analyzed. Experiments were run at two different acceleration rates to compare with experiments presented in prior years at APS DFD meetings and the peak amplitude responses are captured using a high-speed camera. Similar to the instability acceleration, the elastic-plastic transition acceleration is found to be increasing with increase in acceleration rate for a given amplitude and wavelength. The experimental results will be compared to various analytical strength models and prior experimental studies using Newtonian fluids. Authors acknowledge funding support from Los Alamos National Lab subcontract(370333) and DOE-SSAA Grant (DE-NA0001975).

  12. WOOD - PLASTIC COMPOSITES FROM WASTE MATERIALS RESULTED IN THE FURNITURE MANUFACTURING PROCESS

    Directory of Open Access Journals (Sweden)

    Camelia COŞEREANU

    2014-06-01

    Full Text Available The paper presents the application of waste materials resulted in the furniture manufacturing process as components for wood-plastic composites. The composites are produced from industrial byproducts, such as shavings and ABS (acrylonitrile butadiene styrene, without coupling agent. The two components are derived from industrial processes of furniture manufacturing: the first one consists of wood residues resulted from planing machine as planer shavings, and the second one from ABS edge banding operation. A wide array of mixtures varying from 100% ABS to 50% ABS: 50% shavings were used to produce eight variants of boards. Density was determined for each board and the method for the determination of ABS particle size distribution by oscillating screen method using sieve apertures up to 4mm was also applied, in order to establish the particle fractions and the distribution of their sizes. Based on ABS properties, several technologies of manufacturing wood-plastic composites from the waste materials were tested and one of them was selected. The results of the first stage analysis, when the physical integrity and the compactness of the panels’ structures were tested, have shown that a maximum proportion of 30% of wood shavings is accepted in the mixture. On the other hand, the low density of the boards and their porous structure recommend further investigations for thermal and sound insulation applications

  13. Pseudomonas aeruginosa biofilm growth inhibition on medical plastic materials by immobilized esterases and acylase.

    Science.gov (United States)

    Kisch, Johannes Martin; Utpatel, Christian; Hilterhaus, Lutz; Streit, Wolfgang R; Liese, Andreas

    2014-09-01

    Biofilms are matrix-encapsulated cell aggregates that cause problems in technical and health-related areas; for example, 65 % of all human infections are biofilm associated. This is mainly due to their ameliorated resistance against antimicrobials and immune systems. Pseudomonas aeruginosa, a biofilm-forming organism, is commonly responsible for nosocomial infections. Biofilm development is partly mediated by signal molecules, such as acyl-homoserine lactones (AHLs) in Gram-negative bacteria. We applied horse liver esterase, porcine kidney acylase, and porcine liver esterase; these can hydrolyze AHLs, thereby inhibiting biofilm formation. As biofilm infections are often related to foreign material introduced into the human body, we immobilized the enzymes on medical plastic materials. Biofilm formation was quantified by Crystal Violet staining and confocal laser scanning microscopy, revealing up to 97 % (on silicone), 54 % (on polyvinyl chloride), and 77 % (on polyurethane) reduced biomass after 68 h growth.

  14. Homogenization-based continuum plasticity-damage model for ductile failure of materials containing heterogeneities

    Science.gov (United States)

    Ghosh, Somnath; Bai, Jie; Paquet, Daniel

    2009-07-01

    This paper develops an accurate and computationally efficient homogenization-based continuum plasticity-damage (HCPD) model for macroscopic analysis of ductile failure in porous ductile materials containing brittle inclusions. Example of these materials are cast alloys such as aluminum and metal matrix composites. The overall framework of the HCPD model follows the structure of the anisotropic Gurson-Tvergaard-Needleman (GTN) type elasto-plasticity model for porous ductile materials. The HCPD model is assumed to be orthotropic in an evolving material principal coordinate system throughout the deformation history. The GTN model parameters are calibrated from homogenization of evolving variables in representative volume elements (RVE) of the microstructure containing inclusions and voids. Micromechanical analyses for this purpose are conducted by the locally enriched Voronoi cell finite element model (LE-VCFEM) [Hu, C., Ghosh, S., 2008. Locally enhanced Voronoi cell finite element model (LE-VCFEM) for simulating evolving fracture in ductile microstructures containing inclusions. Int. J. Numer. Methods Eng. 76(12), 1955-1992]. The model also introduces a novel void nucleation criterion from micromechanical damage evolution due to combined inclusion and matrix cracking. The paper discusses methods for estimating RVE length scales in microstructures with non-uniform dispersions, as well as macroscopic characteristic length scales for non-local constitutive models. Comparison of results from the anisotropic HCPD model with homogenized micromechanics shows excellent agreement. The HCPD model has a huge efficiency advantage over micromechanics models. Hence, it is a very effective tool in predicting macroscopic damage in structures with direct reference to microstructural composition.

  15. Mechanical behavior of fiber/matrix interfaces in CFRP sheets subjected to plastic deformation

    Directory of Open Access Journals (Sweden)

    Kamiya Ryuta

    2016-01-01

    Full Text Available The use of Carbon Fiber Reinforced Plastic (CFRP is increasing markedly, partially in the aviation industry, but it has been considered that CFRP sheets cannot be formed by press-forming techniques owing to the low ductility of CFRP. Since the mechanical characteristics of CFRP are dominated by the microscale structure, it is possible to improve its formability by optimizing the material structure. Therefore, to improve the formability, the interaction between the carbon fibers and the matrix must be clarified. In this study, microscale analyses were conducted by a finite-element model with cohesive zone elements.

  16. Nonlinear constitutive behavior of ferroelectric materials

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The ferroelectric specimen is considered as an aggregation of many randomly oriented domains. According to this mechanism,a multi-domain mechanical model is developed in this paper. Each domain is represented by one element. The applied stress and electric field are taken to be the stress and electric field in the formula of the driving force of domain switching for each element in the specimen. It means that the macroscopic switching criterion is used for calculating the volume fraction of domain switching for each element. By using the hardening relation between the driving force of domain switching and the volume fraction of domain switching calibrated,the volume fraction of domain switching for each element is calculated. Substituting the stress and electric field and the volume fraction of domain switching into the constitutive equation of ferroelectric material,one can easily get the strain and electric displacement for each element. The macroscopic behavior of the ferroelectric specimen is then directly calculated by volume averaging. Mean-while,the nonlinear finite element analysis for the ferroelectric specimen is carried out. In the finite element simulation,the volume fraction of domain switching for each element is calculated by using the same method mentioned above. The in-teraction between different elements is taken into account in the finite element simulation and the local stress and electric field for each element is obtained. The macroscopic behavior of the specimen is then calculated by volume averaging. The computation results involve the electric butterfly shaped curves of axial strain versus the axial electric field and the hysteresis loops of electric displacement versus the electric field for ferroelectric specimens under the uniaxial coupled stress and electric field loading. The present theoretical prediction agrees reasonably with the experimental results.

  17. Studying the mechanical behavior of a plastic, shock-resisting, antitank landmine.

    Science.gov (United States)

    Kirkpatrick Alberts, W C; Waxier, Roger; Sabatier, James M

    2006-12-01

    Modal behavior in landmines has recently become a topic of interest for acoustic landmine detection. It is well known that landmines exhibit mechanical resonance behavior that enhances the soil velocity over a buried landmine. Recent experimental work by Zagrai et al. [A. Zagrai, D. Donskoy, and A. Ekimov, J. Acoust. Soc. Am. 118 (6), 3619-3628 (2005)] demonstrates the existence of structural modes in several landmines. The work reported herein parallels the work of Zagrai et al. in studying the structural modes of the pressure plate of a plastic, cylindrically symmetric, antitank landmine. The pressure plate is considered to act as an elastically supported thin elastic plate. An observed perturbation of the first symmetric mode of the pressure plate is caused by the landmine's shock-resisting mechanism. This is validated by a lumped element model for the first symmetric mode coupled to the shock-resisting mechanism.

  18. A new bounding-surface plasticity model for cyclic behaviors of saturated clay

    Science.gov (United States)

    Hu, Cun; Liu, Haixiao

    2015-05-01

    A new combined isotropic-kinematic hardening rule is proposed based on the concept of the generalized homological center and the generalization of Masing's rule. The key point of the new hardening rule is that the unloading event can be treated as if it were virgin loading through taking the stress reversal point as the new generalized homological center of the bounding surface. Therefore, a new simple bounding-surface plasticity model with three important features for the cyclic behaviors of saturated clay is developed. Firstly, according to the movement of the generalized homological center, the model can harden not only isotropically but also kinematically to account for the anisotropy and memory the particular loading events. Secondly, the continuous cyclic loading is divided into the first loading, unloading and reloading processes and they are treated differently when calculating the hardening modulus to describe the soil responses accurately. The third feature is taking the generalized homological center as the mapping origin in the mapping rule to reflect the plastic flow in the unloading event. The behaviors of saturated clay for the monotonic and cyclic stress-controlled and strain-controlled triaxial tests are simulated by the model. The prediction results show an encouraging agreement with the experimental data.

  19. A Study of Hardening Behavior Based on a Finite-Deformation Gradient Crystal-Plasticity Model

    CERN Document Server

    Pouriayevali, Habib

    2016-01-01

    A systematic study on the different roles of the governing components of a well-defined finite-deformation gradient crystal-plasticity model proposed by (Gurtin, 2008b) is carried out, in order to visualize the capability of the model in the prediction of a wide range of hardening behaviors as well as rate-dependent, scale-variation and Bauschinger-like responses in a single crystal. A function of accumulation rates of dislocations is employed and viewed as a measure of formation of short-range interactions which impede dislocation movements within a crystal. The model is first represented in the reference configuration for the purpose of numerical implementation, and then implemented in the FEM software ABAQUS via a user-defined subroutine (UEL). Our simulation results reveal that the dissipative gradient-strengthening is also identified as a source of isotropic-hardening behavior, which represents the effect of cold work introduced by (Gurtin and Ohno, 2011). Moreover, plastic flows in predefined slip syste...

  20. Sexual and seasonal plasticity in the emission of social electric signals. Behavioral approach and neural bases.

    Science.gov (United States)

    Silva, Ana; Quintana, Laura; Perrone, Rossana; Sierra, Felipe

    2008-01-01

    Behavior in electric fish includes modulations of a stereotyped electric organ discharge (EOD) in addition to locomotor displays. Gymnotiformes can modulate the EOD rate to produce signals that participate in different behaviors. We studied the reproductive behavior of Brachyhypopomus pinnicaudatus both in the wild and laboratory settings. During the breeding season, fish produce sexually dimorphic social electric signals (SES): males emit three types of chirps (distinguished by their duration and internal structure), and accelerations, whereas females interrupt their EOD. Since these SES imply EOD frequency modulations, the pacemaker nucleus (PN) is involved in their generation and constitutes the main target organ to explore seasonal and sexual plasticity of the CNS. The PN has two types of neurons, pacemakers and relays, which receive modulatory inputs from pre-pacemaker structures. These neurons show an anisotropic rostro-caudal and dorso-ventral distribution that is paralleled by different field potential waveforms in distinct portions of the PN. In vivo glutamate injections in different areas of the PN provoke different kinds of EOD rate modulations. Ventral injections produce chirp-like responses in breeding males and EOD interruptions in breeding females, whereas dorsal injections provoke EOD frequency rises in both sexes. In the non-breeding season, males and females respond with interruptions when stimulated ventrally and frequency rises when injected dorsally. Our results show that changes of glutamate effects in the PN could explain the seasonal and sexual differences in the generation of SES. By means of behavioral recordings both in the wild and in laboratory settings, and by electrophysiological and pharmacological experiments, we have identified sexual and seasonal plasticity of the CNS and explored its underlying mechanisms.

  1. Suppressing effect of goethite on PCDD/F and HCB emissions from plastic materials incineration.

    Science.gov (United States)

    Jin, Guang-Zhu; Lee, Se-Jin; Kang, Jung-Ho; Chang, Yoon-Seok; Chang, Yoon-Young

    2008-02-01

    Polyethylene (PE) and polyvinyl chloride (PVC) are the leading plastics in total production in the world. The incineration of plastic-based materials forms many chlorinated compounds, such as polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs). In this study the addition of goethite (alpha-FeOOH) was investigated to determine its suppressing effect on the emission of PCDD/Fs and hexachlorobenzene (HCB) during the combustion of wastes containing PE and PVC. Goethite was being considered since it acts as a dioxin-suppressing catalyst during incineration. Results showed that incorporation of goethite greatly reduced the generation of PCDD/Fs and HCB in the exhaust gas and fly ash. The concentration of PCDD/Fs in flue gas decreased by 45% for lab-scale and 52% for small incinerator combustion experiments, where the goethite ratios in feed samples were 0.54% and 0.34%, respectively. Under the same conditions, the concentration of HCB in flue gas decreased by 88% and 62%, respectively. The present study showed a possible mechanism of the suppressing effect of the goethite for PCDD/F formation. It is likely that iron chlorides react with particulate carbon to form organo-chlorine compounds and promote PCDD/F formation in the gas phase. XRD analysis of combustion ash revealed that the goethite was partially dehydrated and converted to alpha-Fe(2)O(3) and Fe(3)O(4) but no iron chlorides formation. Therefore the goethite impregnated plastics can contribute the reduction of PCDD/Fs and HCB in the exhaust gas during incineration of MSW.

  2. Phthalates and food-contact materials: enforcing the 2008 European Union plastics legislation.

    Science.gov (United States)

    Petersen, J H; Jensen, L K

    2010-11-01

    The migration of phthalates into foodstuffs from food-contact materials (FCM) is a well-known source of food contamination. In 2005, the European Food Safety Authority finalized its risk assessment for several of the classical phthalate plasticizers. In their risk management procedure the European Commission transformed the tolerable daily intakes established by the Authority into legislative limits for phthalates in both plastic and food simulants, while taking exposure from other sources into consideration. These limits have been into force since 1 July 2008. A detailed interpretation of the regulation of these substances was agreed upon in the European network of FCM reference laboratories. This paper reports results from a Danish control campaign of samples collected by official food inspectors and analysed by a newly validated analytical method run under accreditation. Samples were from FCM producers, FCM importers and importers of packed foodstuffs from third-party countries. Products containing phthalates above the current limits were found in several categories of FCM: conveyor belts (six of six), lids from packed foodstuffs in glasses (eight of 28), tubes for liquid foodstuffs (four of five) and gloves (five of 14). More than 20% of the samples analysed contained dibutylphthalate (DBP) or di-(2-ethylhexyl)phthalate (DEHP) above the compositional limits of 0.05% and 0.1%, respectively. Analysis of residual phthalates in metal lid gaskets instead of analysis of phthalates in the food when controlling foodstuffs packed outside the European Union proved to be an efficient and simple control method. All findings of phthalates were associated with the use of plasticized polyvinylchloride (PVC).

  3. Evaluation of the water-equivalence of plastic materials in low- and high-energy clinical proton beams.

    Science.gov (United States)

    Lourenço, A; Shipley, D; Wellock, N; Thomas, R; Bouchard, H; Kacperek, A; Fracchiolla, F; Lorentini, S; Schwarz, M; MacDougall, N; Royle, G; Palmans, H

    2017-05-21

    The aim of this work was to evaluate the water-equivalence of new trial plastics designed specifically for light-ion beam dosimetry as well as commercially available plastics in clinical proton beams. The water-equivalence of materials was tested by computing a plastic-to-water conversion factor, [Formula: see text]. Trial materials were characterized experimentally in 60 MeV and 226 MeV un-modulated proton beams and the results were compared with Monte Carlo simulations using the FLUKA code. For the high-energy beam, a comparison between the trial plastics and various commercial plastics was also performed using FLUKA and Geant4 Monte Carlo codes. Experimental information was obtained from laterally integrated depth-dose ionization chamber measurements in water, with and without plastic slabs with variable thicknesses in front of the water phantom. Fluence correction factors, [Formula: see text], between water and various materials were also derived using the Monte Carlo method. For the 60 MeV proton beam, [Formula: see text] and [Formula: see text] factors were within 1% from unity for all trial plastics. For the 226 MeV proton beam, experimental [Formula: see text] values deviated from unity by a maximum of about 1% for the three trial plastics and experimental results showed no advantage regarding which of the plastics was the most equivalent to water. Different magnitudes of corrections were found between Geant4 and FLUKA for the various materials due mainly to the use of different nonelastic nuclear data. Nevertheless, for the 226 MeV proton beam, [Formula: see text] correction factors were within 2% from unity for all the materials. Considering the results from the two Monte Carlo codes, PMMA and trial plastic #3 had the smallest [Formula: see text] values, where maximum deviations from unity were 1%, however, PMMA range differed by 16% from that of water. Overall, [Formula: see text] factors were deviating more from unity than [Formula: see text] factors

  4. Prediction of anisotropic material behavior based on multiresolution continuum mechanics in consideration of a characteristic length scale

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Dock Jin; Choi, Jae Boong; Kim, Moon Ki [Sungkyunkwan Univ., Suwon (Korea, Republic of); Chang, Yoon Suk [Kyunghee Univ., Suwon (Korea, Republic of)

    2012-09-15

    New advanced materials have received more attention from many scientists and engineers because of their outstanding chemical, electrical, thermal, optical, and mechanical properties. Since the design of advanced material by experiments requires high cost and time, numerical approaches have always been of great interest. In this paper, finite element analysis of anisotropic material behavior has been carried out based on a multiresolution continuum theory. Gurson Tvergaard Needleman (GTN) damage model has been applied as a constitutive model at macroscale. Effects of plastic anisotropy on deformation behavior are assessed using Hill's 48 yield function for anisotropic material and von Mises yield function for isotropic material, respectively. The material parameters for both isotropic and anisotropic damage models have systematically been determined from microstructure through unit cell modeling. The newly proposed linear approximation of local velocity gradient resolved the underdetermined problem of the previous homogenization process. Anisotropic material behaviors of a tensile specimen have been investigated by the proposed multiresolution continuum theory.

  5. Influence of Niobium on the Beginning of the Plastic Flow of Material during Cold Deformation

    Directory of Open Access Journals (Sweden)

    Stoja Rešković

    2013-01-01

    Full Text Available Investigations were conducted on low-carbon steel and the steel with same chemical composition with addition of microalloying element niobium. While tensile testing was carried out, the thermographic measurement was tacking place simultaneously. A specific behavior of niobium microalloyed steel was noticed. Test results have shown that, in the elastic deformation region, thermoelastic effect occurs, which is more pronounced in niobium microalloyed steel. Start of plastic flow in steel which is not microalloyed with niobium begins later in comparison to the microalloyed steel, and it is conducted so that, at the point of maximum stress, deformation zone is formed within which stresses grow. In steel microalloyed with niobium after proportionality limit, comes the occurrence of the localized increase in temperature and the occurrence of Lüders band, which propagate along the sample forming a deformation zone.

  6. Influence of niobium on the beginning of the plastic flow of material during cold deformation.

    Science.gov (United States)

    Rešković, Stoja; Jandrlić, Ivan

    2013-01-01

    Investigations were conducted on low-carbon steel and the steel with same chemical composition with addition of microalloying element niobium. While tensile testing was carried out, the thermographic measurement was tacking place simultaneously. A specific behavior of niobium microalloyed steel was noticed. Test results have shown that, in the elastic deformation region, thermoelastic effect occurs, which is more pronounced in niobium microalloyed steel. Start of plastic flow in steel which is not microalloyed with niobium begins later in comparison to the microalloyed steel, and it is conducted so that, at the point of maximum stress, deformation zone is formed within which stresses grow. In steel microalloyed with niobium after proportionality limit, comes the occurrence of the localized increase in temperature and the occurrence of Lüders band, which propagate along the sample forming a deformation zone.

  7. Use of recycled plastics in concrete: A critical review.

    Science.gov (United States)

    Gu, Lei; Ozbakkaloglu, Togay

    2016-05-01

    Plastics have become an essential part of our modern lifestyle, and the global plastic production has increased immensely during the past 50years. This has contributed greatly to the production of plastic-related waste. Reuse of waste and recycled plastic materials in concrete mix as an environmental friendly construction material has drawn attention of researchers in recent times, and a large number of studies reporting the behavior of concrete containing waste and recycled plastic materials have been published. This paper summarizes the current published literature until 2015, discussing the material properties and recycling methods of plastic and the influence of plastic materials on the properties of concrete. To provide a comprehensive review, a total of 84 studies were considered, and they were classified into sub categories based on whether they dealt with concrete containing plastic aggregates or plastic fibers. Furthermore, the morphology of concrete containing plastic materials is described in this paper to explain the influence of plastic aggregates and plastic fibers on the properties of concrete. The properties of concretes containing virgin plastic materials were also reviewed to establish their similarities and differences with concrete containing recycled plastics.

  8. A Dissipation Gap Method for full-field measurement-based identification of elasto-plastic material parameters

    KAUST Repository

    Blaysat, Benoît

    2012-05-18

    Using enriched data such as displacement fields obtained from digital image correlation is a pathway to the local identification of material parameters. Up to now, most of the identification techniques for nonlinear models are based on Finite Element Updating Methods. This article explains how an appropriate use of the Dissipation Gap Method can help in this context and be an interesting alternative to these classical techniques. The Dissipation Gap Methods rely on the concept of error in dissipation that has been used mainly for the verification of finite element simulations. We provide here an original application of these founding developments to the identification of material parameters for nonlinear behaviors. The proposed technique and especially the main technical keypoint of building the admissible fields are described in detail. The approach is then illustrated through the identification of heterogeneous isotropic elasto-plastic properties. The basic numerical features highlighted through these simple examples demonstrate this approach to be a promising tool for nonlinear identification. © 2012 John Wiley & Sons, Ltd.

  9. GPA-14, a Gα(i) subunit mediates dopaminergic behavioral plasticity in C. elegans.

    Science.gov (United States)

    Mersha, Mahlet; Formisano, Rosaria; McDonald, Rochelle; Pandey, Pratima; Tavernarakis, Nektarios; Harbinder, Singh

    2013-04-22

    Precise levels of specific neurotransmitters are required for appropriate neuronal functioning. The neurotransmitter dopamine is implicated in modulating behaviors, such as cognition, reward and memory. In the nematode Caenorhabditis elegans, the release of dopamine during behavioral plasticity is in part modulated through an acid-sensing ion channel expressed in its eight dopaminergic neurons. A D2-like C. elegans dopamine receptor DOP-2 co-expresses along with a Gα(i) subunit (GPA-14) in the anterior deirid (ADE) pair of dopaminergic neurons. In follow-up experiments to our recently reported in vitro physical interaction between DOP-2 and GPA-14, we have behaviorally characterized worms carrying deletion mutations in gpa-14 and/or dop-2. We found both mutants to display behavioral abnormalities in habituation as well as associative learning, and exogenous supply of dopamine was able to revert the observed behavioral deficits. The behavioral phenotypes of dop-2 and gpa-14 loss-of-function mutants were found to be remarkably similar, and we did not observe any cumulative defects in their double mutants. Our results provide genetic and phenotypic support to our earlier in vitro results where we had shown that the DOP-2 dopamine receptor and the GPA-14 Gα(i) subunit physically interact with each other. Results from behavioral experiments presented here together with our previous in-vitro work suggests that the DOP-2 functions as a dopamine auto-receptor to modulate two types of learning, anterior touch habituation and chemosensory associative conditioning, through a G-protein complex that comprises GPA-14 as its Gα subunit.

  10. GPA-14, a Gαi subunit mediates dopaminergic behavioral plasticity in C. elegans

    Science.gov (United States)

    2013-01-01

    Background Precise levels of specific neurotransmitters are required for appropriate neuronal functioning. The neurotransmitter dopamine is implicated in modulating behaviors, such as cognition, reward and memory. In the nematode Caenorhabditis elegans, the release of dopamine during behavioral plasticity is in part modulated through an acid-sensing ion channel expressed in its eight dopaminergic neurons. A D2-like C. elegans dopamine receptor DOP-2 co-expresses along with a Gαi subunit (GPA-14) in the anterior deirid (ADE) pair of dopaminergic neurons. Findings In follow-up experiments to our recently reported in vitro physical interaction between DOP-2 and GPA-14, we have behaviorally characterized worms carrying deletion mutations in gpa-14 and/or dop-2. We found both mutants to display behavioral abnormalities in habituation as well as associative learning, and exogenous supply of dopamine was able to revert the observed behavioral deficits. The behavioral phenotypes of dop-2 and gpa-14 loss-of-function mutants were found to be remarkably similar, and we did not observe any cumulative defects in their double mutants. Conclusion Our results provide genetic and phenotypic support to our earlier in vitro results where we had shown that the DOP-2 dopamine receptor and the GPA-14 Gαi subunit physically interact with each other. Results from behavioral experiments presented here together with our previous in-vitro work suggests that the DOP-2 functions as a dopamine auto-receptor to modulate two types of learning, anterior touch habituation and chemosensory associative conditioning, through a G-protein complex that comprises GPA-14 as its Gα subunit. PMID:23607404

  11. SOME ASPECTS REGARDING THE DEGREE OF CONSERVATION OF THE CREAM PACKAED IN PLASTIC MATERIALS

    Directory of Open Access Journals (Sweden)

    Ioana Rebenciuc

    2010-01-01

    Full Text Available The prolongation of the product shelf life is directly influenced by the quality of the relation established between thepacking method, package and product. In this situation, the package properties play a primary role in ensuring theprotection and preservation function. This paper’s purpose is to present and analyze cream and types of plastic foodpackage, in relation with the food product; plastic food package still being the most used for the packaging of diaryproducts.The cream packagings have been tested specifically: white polypropylene packagings and coloured sealingends as well. The security of food stuff packaging materials is based on the insurance of the fact that while coming intocontact with food, the unsafe chemical substances do not migrate into it. The substance quantity limit that can betransmitted to product must be determined and limited at a level that will not cause any changes in food stuff. Initiallyanalyses on the product as well as on the package have been made. Then, analyses at 7 day- intervals during a month ofstorage have been made.

  12. CATALYTIC CONVERSION OF MUNICIPAL WASTE PLASTIC INTO GASOLINE-RANGE PRODUCTS OVER MESOPOROUS MATERIALS

    Institute of Scientific and Technical Information of China (English)

    Jorge Norberto Beltramini

    2006-01-01

    In the last 20 years, it has become apparent that waste produced from plastics was becoming an environmental problem because of their low biodegradability. Though several methods have been proposed for recycling waste plastics, it is generally accepted that material recovery is not a long-term solution to the present problem, and that energy or chemical recovery is a more attractive alternative, including cracking into the monomer constituents, combustion to produce energy, and thermal or catalytic conversion to produce useful intermediate chemicals.This paper is a contribution in the area of the last option for energy recovery. There have been a number of publications reporting the use of molecular sieves and amorphous silica-alumina catalysts for the cracking of polymers into a range of hydrocarbons. The research work reported here demonstrates the ability of mesoporous catalysts in cracking polyethylene into gasoline range products.It was found that for mesoporous MCM-41 catalysts, its cracking activity increases with its crystallinity, displaying higher activity with smaller pore diameters. The hydrocarbon product distribution strongly indicates a carbenium ion cracking mechanism. The product distribution was also compared with those obtained from thermal cracking tests.

  13. Formation of nanocrystalline surface layers in various metallic materials by near surface severe plastic deformation

    Directory of Open Access Journals (Sweden)

    Masahide Sato, Nobuhiro Tsuji, Yoritoshi Minamino and Yuichiro Koizumi

    2004-01-01

    Full Text Available The surface of the various kinds of metallic materials sheets were severely deformed by wire-brushing at ambient temperature to achieve nanocrystalline surface layer. The surface layers of the metallic materials developed by the near surface severe plastic deformation (NS-SPD were characterized by means of TEM. Nearly equiaxed nanocrystals with grain sizes ranging from 30 to 200 nm were observed in the near surface regions of all the severely scratched metallic materials, which are Ti-added ultra-low carbon interstitial free steel, austenitic stainless steel (SUS304, 99.99 wt.%Al, commercial purity aluminum (A1050 and A1100, Al–Mg alloy (A5083, Al-4 wt.%Cu alloy, OFHC-Cu (C1020, Cu–Zn alloy (C2600 and Pb-1.5%Sn alloy. In case of the 1050-H24 aluminum, the depth of the surface nanocrystalline layer was about 15 μm. It was clarified that wire-brushing is an effective way of NS-SPD, and surface nanocrystallization can be easily achieved in most of metallic materials.

  14. Pyrolysis of municipal plastic wastes II: Influence of raw material composition under catalytic conditions.

    Science.gov (United States)

    López, A; de Marco, I; Caballero, B M; Laresgoiti, M F; Adrados, A; Torres, A

    2011-01-01

    In this work, the results obtained in catalytic pyrolysis of three plastic waste streams which are the rejects of an industrial packing wastes sorting plant are presented. The samples have been pyrolysed in a 3.5 dm(3) reactor under semi-batch conditions at 440 °C for 30 min in nitrogen atmosphere. Commercial ZSM-5 zeolite has been used as catalyst in liquid phase contact. In every case, high HHV gases and liquids which can be useful as fuels or source of chemicals are obtained. A solid fraction composed of the inorganic material contained in the raw materials and some char formed in the pyrolysis process is also obtained. The zeolite has shown to be very effective to produce liquids with great aromatics content and C3-C4 fraction rich gases, even though the raw material was mainly composed of polyolefins. The characteristics of the pyrolysis products as well as the effect of the catalyst vary depending on the composition of the raw material. When paper rich samples are pyrolysed, ZSM-5 zeolite increases water production and reduces CO and CO(2) generation. If stepwise pyrolysis is applied to such sample, the aqueous liquid phase can be separated from the organic liquid fraction in a first low temperature step.

  15. Synaptic plasticity in a recurrent neural network for versatile and adaptive behaviors of a walking robot

    Directory of Open Access Journals (Sweden)

    Eduard eGrinke

    2015-10-01

    Full Text Available Walking animals, like insects, with little neural computing can effectively perform complex behaviors. They can walk around their environment, escape from corners/deadlocks, and avoid or climb over obstacles. While performing all these behaviors, they can also adapt their movements to deal with an unknown situation. As a consequence, they successfully navigate through their complex environment. The versatile and adaptive abilities are the result of an integration of several ingredients embedded in their sensorimotor loop. Biological studies reveal that the ingredients include neural dynamics, plasticity, sensory feedback, and biomechanics. Generating such versatile and adaptive behaviors for a walking robot is a challenging task. In this study, we present a bio-inspired approach to solve this task. Specifically, the approach combines neural mechanisms with plasticity, sensory feedback, and biomechanics. The neural mechanisms consist of adaptive neural sensory processing and modular neural locomotion control. The sensory processing is based on a small recurrent network consisting of two fully connected neurons. Online correlation-based learning with synaptic scaling is applied to adequately change the connections of the network. By doing so, we can effectively exploit neural dynamics (i.e., hysteresis effects and single attractors in the network to generate different turning angles with short-term memory for a biomechanical walking robot. The turning information is transmitted as descending steering signals to the locomotion control which translates the signals into motor actions. As a result, the robot can walk around and adapt its turning angle for avoiding obstacles in different situations as well as escaping from sharp corners or deadlocks. Using backbone joint control embedded in the locomotion control allows the robot to climb over small obstacles. Consequently, it can successfully explore and navigate in complex environments.

  16. Chronic alcohol exposure alters behavioral and synaptic plasticity of the rodent prefrontal cortex.

    Directory of Open Access Journals (Sweden)

    Sven Kroener

    Full Text Available In the present study, we used a mouse model of chronic intermittent ethanol (CIE exposure to examine how CIE alters the plasticity of the medial prefrontal cortex (mPFC. In acute slices obtained either immediately or 1-week after the last episode of alcohol exposure, voltage-clamp recording of excitatory post-synaptic currents (EPSCs in mPFC layer V pyramidal neurons revealed that CIE exposure resulted in an increase in the NMDA/AMPA current ratio. This increase appeared to result from a selective increase in the NMDA component of the EPSC. Consistent with this, Western blot analysis of the postsynaptic density fraction showed that while there was no change in expression of the AMPA GluR1 subunit, NMDA NR1 and NRB subunits were significantly increased in CIE exposed mice when examined immediately after the last episode of alcohol exposure. Unexpectedly, this increase in NR1 and NR2B was no longer observed after 1-week of withdrawal in spite of a persistent increase in synaptic NMDA currents. Analysis of spines on the basal dendrites of layer V neurons revealed that while the total density of spines was not altered, there was a selective increase in the density of mushroom-type spines following CIE exposure. Examination of NMDA-receptor mediated spike-timing-dependent plasticity (STDP showed that CIE exposure was associated with altered expression of long-term potentiation (LTP. Lastly, behavioral studies using an attentional set-shifting task that depends upon the mPFC for optimal performance revealed deficits in cognitive flexibility in CIE exposed mice when tested up to 1-week after the last episode of alcohol exposure. Taken together, these observations are consistent with those in human alcoholics showing protracted deficits in executive function, and suggest these deficits may be associated with alterations in synaptic plasticity in the mPFC.

  17. SURFACE EFFECT ON NANOSIZED VOID GROWTH IN A RIGID-PERFECTLY PLASTIC MATERIAL

    Institute of Scientific and Technical Information of China (English)

    Tong Hui; Yiheng Chen

    2008-01-01

    The influence of the surface effect on the nanosized spherical void growth in a rigid-perfectly plastic material is analyzed and the mechanism of the nanosized void growth with high triaxiality is given. Based on the Rice and Tracey model for a macro void growth, the present model is proposed to account for the nanosized void growth under a uniform remote strain rate field with consideration on the surface effect. It is concluded that the surface effect yields an evident resistant influence on the nanosized void growth. That is, this influence decays as the void radius increases. With high triaxiality, the nanosized void growth is divided into two stages:the initial stage and the mature stage. At the first stage, the void grows slowly and the influence of surface effect is relatively weak, whereas at the second stage, the influene is significant and the void grows drastically.

  18. The Role of GluK4 in Synaptic Plasticity and Affective Behavior in Mice

    Science.gov (United States)

    Catches, Justin Samuel

    Kainate receptors (KARs) are glutamate-gated ion channels that signal through both ionotropic and metabotropic pathways (Contractor et al., 2011). Combinations of five KAR subunits (GluK1-5) form tetrameric receptors with GluK1, GluK2, and GluK3 able to form functional homomeric channels. The high-affinity subunits, GluK4 and GluK5, do not form homomeric channels but modify the properties of heteromeric receptors. Expression of the GluK4 receptor subunit in the forebrain is restricted to the CA3 region of the hippocampus and dentate gyrus regions where KARs modulate synaptic plasticity. In this study, ablation of Grik4, which encodes GluK4, in mice reduced KAR synaptic currents and altered activation properties of postsynaptic receptors but left two forms of presynaptic short-term plasticity intact. Disruption of both Grik4 and Grik5 caused complete loss of the postsynaptic ionotropic KAR current and impaired presynaptic frequency facilitation. Additionally, KAR surface expression was altered at pre- and postsynaptic sites at the MF synapse. Despite the loss of ionotropic signaling, KAR-mediated inhibition of the slow afterhyperpolarization current, which is dependent on metabotropic signaling, was intact in CA3 neurons. Long-term potentiation at the MF-CA3 synapse was reduced, likely through a loss of KAR modulation of excitability of the presynaptic MF axons. Genetic variants in the human GRIK4 gene alter the susceptibility for affective disorders (Bloss and Hunter, 2010). We found that ablation of Grik4 in mice resulted in reduced anxiety and an antidepressant-like phenotype. In the elevated zero-maze, a test for anxiety and risk taking behavior, and in two anxiogenic tests, marble-burying and novelty-induced suppression of feeding, anxiety-like behavior was consistently reduced in knockout animals. In the forced swim, a test of learned helplessness used to determine depression-like behavior, knockout mice demonstrated significantly less immobility suggesting

  19. An exact solution for the history-dependent material and delamination behavior of laminated plates subjected to cylindrical bending

    Energy Technology Data Exchange (ETDEWEB)

    Williams, Todd O [Los Alamos National Laboratory

    2009-01-01

    The exact solution for the history-dependent behavior of laminated plates subjected to cylindrical bending is presented. The solution represents the extension of Pagano's solution to consider arbitrary types of constitutive behaviors for the individual lamina as well as arbitrary types of cohesive zones models for delamination behavior. Examples of the possible types of material behavior are plasticity, viscoelasticity, viscoplasticity, and damaging. Examples of possible CZMs that can be considered are linear, nonlinear hardening, as well as nonlinear with softening. The resulting solution is intended as a benchmark solution for considering the predictive capabilities of different plate theories. Initial results are presented for several types of history-dependent material behaviors. It is shown that the plate response in the presence of history-dependent behaviors can differ dramatically from the elastic response. These results have strong implications for what constitutes an appropriate plate theory for modeling such behaviors.

  20. Greenhouse gas emissions from the treatment of household plastic containers and packaging: replacement with biomass-based materials.

    OpenAIRE

    Yano, Junya; Hirai, Yasuhiro; Sakai, Shin-ichi; Tsubota, Jun

    2014-01-01

    The purpose of this study was to quantify the life-cycle greenhouse gas (GHG) emissions reduction that could be achieved by replacement of fossil-derived materials with biodegradable, biomass-based materials for household plastic containers and packaging, considering a variety of their treatment options. The biomass-based materials were 100% polylactide or a combination of polybutylene succinate adipate and polylactide. A scenario analysis was conducted considering alternative recycling metho...

  1. Life Cycle Assessment of Common Plastic Packaging for Reducing Environmental Impact and Material Consumption

    Directory of Open Access Journals (Sweden)

    Visvaldas Varžinskas

    2009-12-01

    the Faculty of Design and Technologies, Kaunas University of Technology, together with packaging and environmental protection specialists of the University, and in cooperation with the Department of Printed Publications and Packaging of the Ukrainian Print Academy. The present paper analyses certain basic findings of the study on the possibilities of improving the ecological level of packaging within the framework of the project. It is stated that appropriate investigation of packaging, its production and application has to be performed in order to prove that the packaging was produced in compliance with preventive and other principles; this investigation is related to a wide variety of package testing, some of which has not yet got methodology acknowledged at a sufficient level (the EU or groups of countries. Therefore, one of the research directions in the above mentioned project, discussed in the present paper, is related to developing a single system, recognized throughout the EU, which would enable researchers to perform the required tests confirming the packaging quality compliance with the environmental requirements. The paper analyzes the EU prevention regulations for reducing the amount of raw material and the system of checking the realization of the requirements based on identification of critical areas, aimed at reaching the lowest possible package weight and/or volume, consequently, the minimum waste amount, without increasing the amount of faulty products and product waste. The paper presents the findings of the research obtained in assessing the life cycle, when applying the Ecoindicator'99 qualitative analysis, concerning the impact of common plastic packages and processes on the environment during manufacturing, usage and disposal. Compression test results of common type plastic packaging construction are presented, which allow us to assess the impact of the package shape and construction upon the packaging reliability and minimization of its mass.

  2. Strategies to improve the mechanical properties of starch-based materials: plasticization and natural fibers reinforcement

    Directory of Open Access Journals (Sweden)

    A. Lopez-Gil

    2014-01-01

    Full Text Available Biodegradable polymers are starting to be introduced as raw materials in the food-packaging market. Nevertheless, their price is very high. Starch, a fully biodegradable and bioderived polymer is a very interesting alternative due to its very low price. However, the use of starch as the polymer matrix for the production of rigid food packaging, such as trays, is limited due to its poor mechanical properties, high hidrophilicity and high density. This work presents two strategies to overcome the poor mechanical properties of starch. First, the plasticization of starch with several amounts of glycerol to produce thermoplastic starch (TPS and second, the production of biocomposites by reinforcing TPS with promising fibers, such as barley straw and grape waste. The mechanical properties obtained are compared with the values predicted by models used in the field of composites; law of mixtures, Kerner-Nielsen and Halpin-Tsai. To evaluate if the materials developed are suitable for the production of food-packaging trays, the TPS-based materials with better mechanical properties were compared with commercial grades of oil-based polymers, polypropylene (PP and polyethylene-terphthalate (PET, and a biodegradable polymer, polylactic acid (PLA.

  3. Measurement of the Specific Heat of Plastic Waste/Fly Ash Composite Material Using Differential Scanning Calorimetry

    Science.gov (United States)

    Fujino, J.; Honda, T.

    2009-06-01

    Plastic waste/fly ash composite, which is made mostly from plastic waste and fly ash, is one of the materials developed for the purpose of recycling. Currently, the composite is used for cable troughs shielding underground lines. However, there exists little information concerning the thermophysical properties of the composite. Thermophysical properties and the structure of the composite must be determined to estimate the heat transfer in the composite and create the different proportions of the composite material. This article deals with measurements of the specific heat of the plastic waste/fly ash composite and its components using a differential scanning calorimeter. The composite sample, which ranged from 10 mg to 19 mg in mass, was cut from a cable trough. The standard reference material is synthetic sapphire disks of 19.6 mg and 29.6 mg in mass. The specific heat of the plastic waste/fly ash composite increases from 1.25 kJ · kg-1 · K-1 to 1.59 kJ · kg-1 · K-1 at temperatures from 305 K to 360 K. The uncertainty for the specific heat data of the composite is estimated to be about 4 %. In addition, the specific heat value depends heavily on the content of the plastic waste.

  4. Altering strength and plastic deformation behavior via alloying and laminated structure in nanocrystalline metals

    Energy Technology Data Exchange (ETDEWEB)

    Gu, C. [State Key Laboratory for Mechanical Behavior of Material, Xi' an Jiaotong University, Xi' an 710049 (China); Wang, F., E-mail: wangfei@mail.xjtu.edu.cn [State Key Laboratory for Strength and Vibration of Mechanical Structures, Xi' an Jiaotong University, Xi' an 710049 (China); Huang, P., E-mail: huangping@mail.xjtu.edu.cn [State Key Laboratory for Mechanical Behavior of Material, Xi' an Jiaotong University, Xi' an 710049 (China); Lu, T.J. [State Key Laboratory for Strength and Vibration of Mechanical Structures, Xi' an Jiaotong University, Xi' an 710049 (China); MOE Key Laboratory for Multifunctional Materials and Structures, Xi' an Jiaotong University, Xi' an 710049 (China); Xu, K.W. [State Key Laboratory for Mechanical Behavior of Material, Xi' an Jiaotong University, Xi' an 710049 (China)

    2015-07-29

    Nanoindentation and electron microscope techniques have been performed on sputtering deposited monolayered nanocrystalline CuNb and multilayered CuNb/Cu thin films. Microstructural features, hardness and surface morphologies of residual indentation have been evaluated to identify the effects of alloying and laminated structure on strength and plastic deformation behavior of nanocrystalline metals. By altering the content of Nb in CuNb alloy and adding crystalline Cu layers into CuNb alloy, the volume fraction of amorphous phase in CuNb alloy and interface structures changed dramatically, resulting in various trends that are related to hardness, indentation induced pileup and shear banding deformation. Based on the experimental results, the dominant deformation mechanisms of the CuNb and CuNb/Cu thin films with various Nb contents were proposed and extended to be discussed.

  5. A coupled damage-plasticity model for the cyclic behavior of shear-loaded interfaces

    Science.gov (United States)

    Carrara, P.; De Lorenzis, L.

    2015-12-01

    The present work proposes a novel thermodynamically consistent model for the behavior of interfaces under shear (i.e. mode-II) cyclic loading conditions. The interface behavior is defined coupling damage and plasticity. The admissible states' domain is formulated restricting the tangential interface stress to non-negative values, which makes the model suitable e.g. for interfaces with thin adherends. Linear softening is assumed so as to reproduce, under monotonic conditions, a bilinear mode-II interface law. Two damage variables govern respectively the loss of strength and of stiffness of the interface. The proposed model needs the evaluation of only four independent parameters, i.e. three defining the monotonic mode-II interface law, and one ruling the fatigue behavior. This limited number of parameters and their clear physical meaning facilitate experimental calibration. Model predictions are compared with experimental results on fiber reinforced polymer sheets externally bonded to concrete involving different load histories, and an excellent agreement is obtained.

  6. Omega-3 fatty acid deficiency during brain maturation reduces neuronal and behavioral plasticity in adulthood.

    Directory of Open Access Journals (Sweden)

    Harsharan Singh Bhatia

    Full Text Available Omega-3-fatty acid DHA is a structural component of brain plasma membranes, thereby crucial for neuronal signaling; however, the brain is inefficient at synthesizing DHA. We have asked how levels of dietary n-3 fatty acids during brain growth would affect brain function and plasticity during adult life. Pregnant rats and their male offspring were fed an n-3 adequate diet or n-3 deficient diets for 15 weeks. Results showed that the n-3 deficiency increased parameters of anxiety-like behavior using open field and elevated plus maze tests in the male offspring. Behavioral changes were accompanied by a level reduction in the anxiolytic-related neuropeptide Y-1 receptor, and an increase in the anxiogenic-related glucocorticoid receptor in the cognitive related frontal cortex, hypothalamus and hippocampus. The n-3 deficiency reduced brain levels of docosahexaenoic acid (DHA and increased the ratio n-6/n-3 assessed by gas chromatography. The n-3 deficiency reduced the levels of BDNF and signaling through the BDNF receptor TrkB, in proportion to brain DHA levels, and reduced the activation of the BDNF-related signaling molecule CREB in selected brain regions. The n-3 deficiency also disrupted the insulin signaling pathways as evidenced by changes in insulin receptor (IR and insulin receptor substrate (IRS. DHA deficiency during brain maturation reduces plasticity and compromises brain function in adulthood. Adequate levels of dietary DHA seem crucial for building long-term neuronal resilience for optimal brain performance and aiding in the battle against neurological disorders.

  7. Influence of reaction parameters on brown coal-polyolefinic plastic co-pyrolysis behavior

    Energy Technology Data Exchange (ETDEWEB)

    Sharypov, V.I.; Beregovtsova, N.G.; Kuznetsov, B.N. [Institute of Chemistry and Chemical Technology SB RAS, K.Marx Str. 42, 660049 Krasnoyarsk (Russian Federation); Cebolla, V.L. [Instituto de Carboquimica, CSIC, Miguel Luesma, 4, 50015 Zaragoza (Spain); Collura, S.; Finqueneisel, G.; Zimny, T.; Weber, J.V. [Laboratoire de Chimie et Applications, Universite de Metz, rue V.Demange, 57500 Saint-Avold (France)

    2007-03-15

    Co-processing of polyolefinic polymers with Kansk-Achinsk (Russia) brown coal was investigated by thermogravimetry (TG) and autoclave pyrolysis under argon and hydrogen pressure in catalytic conditions (or not). Gas chromatography-mass spectrometry (GC-MS) and high performance thin layer chromatography (HPTLC) were used to analyze the distillate products. Some synergistic effects indicate chemical interaction between the products of thermal decomposition of coal and plastic. In co-pyrolysis under H{sub 2} a significant increasing of coal conversion degree as a function of polymer amount in feedstock was found. Simultaneously the coal promoted formation of distillate products from polymers. Some alkyl aromatic and O-containing substances were detected in co-pyrolysis fraction boiling in the range 180-350 C, indicating interactions between coal and plastic. Iron containing ore materials, modified by mechanochemical treatment, demonstrated a catalytic activity in hydropyrolysis process. In catalytic conditions, increases of the mixtures conversion degree by 9-13 wt.%, of distillate fraction yields by 1.2-1.6 times and a decrease of olefins and polycyclic components were observed. (author)

  8. Identifying Structure-Property Relationships Through DREAM.3D Representative Volume Elements and DAMASK Crystal Plasticity Simulations: An Integrated Computational Materials Engineering Approach

    Science.gov (United States)

    Diehl, Martin; Groeber, Michael; Haase, Christian; Molodov, Dmitri A.; Roters, Franz; Raabe, Dierk

    2017-03-01

    Predicting, understanding, and controlling the mechanical behavior is the most important task when designing structural materials. Modern alloy systems—in which multiple deformation mechanisms, phases, and defects are introduced to overcome the inverse strength-ductility relationship—give raise to multiple possibilities for modifying the deformation behavior, rendering traditional, exclusively experimentally-based alloy development workflows inappropriate. For fast and efficient alloy design, it is therefore desirable to predict the mechanical performance of candidate alloys by simulation studies to replace time- and resource-consuming mechanical tests. Simulation tools suitable for this task need to correctly predict the mechanical behavior in dependence of alloy composition, microstructure, texture, phase fractions, and processing history. Here, an integrated computational materials engineering approach based on the open source software packages DREAM.3D and DAMASK (Düsseldorf Advanced Materials Simulation Kit) that enables such virtual material development is presented. More specific, our approach consists of the following three steps: (1) acquire statistical quantities that describe a microstructure, (2) build a representative volume element based on these quantities employing DREAM.3D, and (3) evaluate the representative volume using a predictive crystal plasticity material model provided by DAMASK. Exemplarily, these steps are here conducted for a high-manganese steel.

  9. Identifying Structure-Property Relationships Through DREAM.3D Representative Volume Elements and DAMASK Crystal Plasticity Simulations: An Integrated Computational Materials Engineering Approach

    Science.gov (United States)

    Diehl, Martin; Groeber, Michael; Haase, Christian; Molodov, Dmitri A.; Roters, Franz; Raabe, Dierk

    2017-05-01

    Predicting, understanding, and controlling the mechanical behavior is the most important task when designing structural materials. Modern alloy systems—in which multiple deformation mechanisms, phases, and defects are introduced to overcome the inverse strength-ductility relationship—give raise to multiple possibilities for modifying the deformation behavior, rendering traditional, exclusively experimentally-based alloy development workflows inappropriate. For fast and efficient alloy design, it is therefore desirable to predict the mechanical performance of candidate alloys by simulation studies to replace time- and resource-consuming mechanical tests. Simulation tools suitable for this task need to correctly predict the mechanical behavior in dependence of alloy composition, microstructure, texture, phase fractions, and processing history. Here, an integrated computational materials engineering approach based on the open source software packages DREAM.3D and DAMASK (Düsseldorf Advanced Materials Simulation Kit) that enables such virtual material development is presented. More specific, our approach consists of the following three steps: (1) acquire statistical quantities that describe a microstructure, (2) build a representative volume element based on these quantities employing DREAM.3D, and (3) evaluate the representative volume using a predictive crystal plasticity material model provided by DAMASK. Exemplarily, these steps are here conducted for a high-manganese steel.

  10. Modeling the triaxial behavior of riverbed and blasted quarried rockfill materials using hardening soil model

    Institute of Scientific and Technical Information of China (English)

    N.P. Honkanadavar; K.G. Sharma

    2016-01-01

    Riverbed modeled rockfill material from Noa Dehing dam project, Arunachal Pradesh, India and blasted quarried modeled rockfill material from Kol dam project, Himachal Pradesh, India were considered for this research. Riverbed rockfill material is rounded to sub-rounded and quarried rockfill material is angular to sub-angular in shape. Prototype rockfill materials were modeled into maximum particle size (dmax) of 4.75 mm, 10 mm, 19 mm, 25 mm, 50 mm and 80 mm for testing in the laboratory. Consolidated drained triaxial tests were conducted on modeled rockfill materials with a specimen size of 381 mm in diameter and 813 mm in height to study the stressestrainevolume change behavior for both rockfill materials. Index properties, i.e. uncompacted void content (UVC) and uniaxial compressive strength (UCS), were determined for both rockfill materials in association with material parameters. An elasto-plastic hardening soil (HS) constitutive model was used to predict the behavior of modeled rockfill materials. Comparing the predicted and observed stressestrainevolume change behavior, it is found that both observed and predicted behaviors match closely. The procedures were developed to predict the shear strength and elastic parameters of rockfill materials using the index properties, i.e. UCS, UVC and relative density (RD), and predictions were made satisfactorily. Comparing the predicted and experi-mentally determined shear strengths and elastic parameters, it is observed that both values match closely. Then these procedures were used to predict the elastic and shear strength parameters of large-size prototype rockfill materials. Correlations were also developed between index properties and ma-terial strength parameters (dilatancy angle, j, and initial void ratio, einit, required for HS model) of modeled rockfill materials and the same correlations were used to predict the strength parameters for the prototype rockfill materials. Using the predicted material parameters

  11. Non-Hertzian behavior in binary collisions of plastic balls derived from impact acoustics.

    Science.gov (United States)

    Riner, Joshua; Petculescu, Andi

    2010-07-01

    This paper presents slight deviations from Hertz's impact law, inferred from acoustic signatures of polypropylene ball collisions. An impact acoustics model is used to fit the acoustic data. The model is built upon a generalized relationship between impact force (F) and deformation (xi) of the form F=kappaxi(alpha). Agreement with experiment is reached when alpha and kappa differ from Hertz's values by -6.25% and +1%, respectively. The difference is ascribable to non-idealities such as slight material inhomogeneities, impact-point asymmetry, plasticity etc. Also, the collision energy released as sound, which is usually dismissed as negligible, is derived from data fitting. The acoustic-to-incident energy ratio, dependent on impact duration, is constrained to be on the order of 100 ppm.

  12. Behavioral plasticity, behavioral syndromes and animal personality in crustacean decapods: An imperfect map is better than no map

    Directory of Open Access Journals (Sweden)

    Francesca GHERARDI, Laura AQUILONI, Elena TRICARICO

    2012-08-01

    Full Text Available Despite their key role as model organisms in many behavioral studies, crustacean decapods have been only slightly touched upon by the recent surge of scientific interest in animal personality. Only seven articles investigated the issue in a handful of species among hermit crabs, crabs, and crayfish. Obviously, a limited number of publications does not mean that personality is rare in decapods. On the contrary, few studies might be the result of a form of reluctance by behavioral ecologists to deal with such a phenomenon in these and other invertebrates. This reluctance contrasts with the enthusiasm shown in tackling the beha­vioral plasticity issue. Here we discuss the possible theoretical and methodological difficulties raised by applying the animal personality perspective to decapods and analyze implications of personality studies for their ecology, conservation, and welfare. By highlighting gaps in knowledge and directions of future research, our intention is to increase scientific emphasis on the issue [Current Zoology 58 (4: 567–579, 2012].

  13. Features of energy impact on a billet material when cutting with outstripping plastic deformation

    Directory of Open Access Journals (Sweden)

    V. M. Yaroslavtsev

    2014-01-01

    Full Text Available In the last decades the so-called combined machining methods based on parallel, serial or parallelserial combination of different types of energy impacts on the billet are designed and developed. Combination of two or more sources of external energy in one method of machining can be directed to the solution of different technological tasks, such as: improvement of a basic method to enhance technicaland-economic and technological indicators of machining, expansion of technological capabilities of the method, increase of reliability and stability of technological process to produce details, etc. Besides, the combined methods of machining are considered as one of the means, which enables reducing the number of operations in technological process, allows the growth of workforce productivity.When developing the combined technologies, one of the main scientific tasks is to define the general regularities of interaction and mutual influence of the energy fluxes brought to the zone of machining. The result of such mutual influence becomes apparent from the forming technological parameters of machining and determines the most rational operating conditions of technological process.In the context of conducted in BMSTU researches on the combined cutting method with outstripping plastic deformation (OPD the mutual influence of the energetic components of machining has been quantitatively assessed. The paper shows a direct relationship between the rational ratio of the two types of the mechanical energy brought in the machining zone, the machining conditions, and the optimum operating conditions.The paper offers a physical model of chip formation when machining with OPD. The essence of model is that specific works spent on material deformation of a cut-off layer are quantitatively compared at usual cutting and at cutting with OPD. It is experimentally confirmed that the final strain-deformed material states of a cut-off layer, essentially, coincide in both

  14. Polycarbonate as an Elasto-Plastic Material Model for Simulation of the Microstructure Hot Imprint Process

    Directory of Open Access Journals (Sweden)

    Rokas Šakalys

    2013-08-01

    Full Text Available The thermal imprint process of polymer micro-patterning is widely applied in areas such as manufacturing of optical parts, solar energy, bio-mechanical devices and chemical chips. Polycarbonate (PC, as an amorphous polymer, is often used in thermoforming processes because of its good replication characteristics. In order to obtain replicas of the best quality, the imprint parameters (e.g., pressure, temperature, time, etc. must be determined. Therefore finite element model of the hot imprint process of lamellar periodical microstructure into PC has been created using COMSOL Multiphysics. The mathematical model of the hot imprint process includes three steps: heating, imprinting and demolding. The material properties of amorphous PC strongly depend on the imprint temperature and loading pressure. Polycarbonate was modelled as an elasto-plastic material, since it was analyzed below the glass transition temperature. The hot imprint model was solved using the heat transfer and the solid stress-strain application modes with thermal contact problem between the mold and polycarbonate. It was used for the evaluation of temperature and stress distributions in the polycarbonate during the hot imprint process. The quality of the replica, by means of lands filling ratio, was determined as well.

  15. Polycarbonate as an elasto-plastic material model for simulation of the microstructure hot imprint process.

    Science.gov (United States)

    Narijauskaitė, Birutė; Palevičius, Arvydas; Gaidys, Rimvydas; Janušas, Giedrius; Sakalys, Rokas

    2013-08-22

    The thermal imprint process of polymer micro-patterning is widely applied in areas such as manufacturing of optical parts, solar energy, bio-mechanical devices and chemical chips. Polycarbonate (PC), as an amorphous polymer, is often used in thermoforming processes because of its good replication characteristics. In order to obtain replicas of the best quality, the imprint parameters (e.g., pressure, temperature, time, etc.) must be determined. Therefore finite element model of the hot imprint process of lamellar periodical microstructure into PC has been created using COMSOL Multiphysics. The mathematical model of the hot imprint process includes three steps: heating, imprinting and demolding. The material properties of amorphous PC strongly depend on the imprint temperature and loading pressure. Polycarbonate was modelled as an elasto-plastic material, since it was analyzed below the glass transition temperature. The hot imprint model was solved using the heat transfer and the solid stress-strain application modes with thermal contact problem between the mold and polycarbonate. It was used for the evaluation of temperature and stress distributions in the polycarbonate during the hot imprint process. The quality of the replica, by means of lands filling ratio, was determined as well.

  16. Characterization of Elastic-plastic Material Properties for IMC Layer of ENEPIG by Using Reverse Algorithm

    Science.gov (United States)

    Kim, Jong-Min; Lee, Hyun-Boo; Chang, Yoon-Suk; Choi, Jae-Boong; Kim, Young-Jin; Ji, Kum-Young

    2010-05-01

    Recently, the reliability assurance of lead-free solder to prevent environmental contamination is quite important issue for chip-scale packaging. Although lots of efforts have been devoted to the solder undergone drop, shear and creep loads, there was a little research on IMC due primarily to its thickness restriction and geometric irregularity. However, the IMC is known as the weakest layer governing failures of the solder joint. The present work is to characterize realistic material properties of the IMC for ENEPIG process. Lee's modified reverse algorithm was adopted to determine elastic-plastic stress-strain curve and so forth, after examining several methods, which requires inherently elastic data. In this context, a series of nano-indentation tests as well as corresponding simulations were carried out by changing indentation depths from 200 to 400 nm and strain rates from 0.05 to 0.10 1/s. It would be conclude that effect of strain rate is relatively small and IMC layer should be more than 5 times of indentation depth when using the recommended method, which are applicable to generate realistic material properties for further diverse structural integrity simulations.

  17. Finite element implementation of the Hoek-Brown material model with general strain softening behavior

    DEFF Research Database (Denmark)

    Sørensen, Emil Smed; Clausen, Johan Christian; Damkilde, Lars

    2015-01-01

    A numerical implementation of the Hoek–Brown criterion is presented, which is capable of modeling different post-failure behaviors observed in jointed rock mass. This is done by making the material parameters a function of the accumulated plastic strain. The implementation is for use in finite...... element calculations, and is based on the return mapping framework. The updated stress state together with the consistent constitutive matrix is found in principal stress space based on the principles of boundary planes. The implementation is verified through the simulation of a tunnel excavation...

  18. Effects of nanoparticle zinc oxide on spatial cognition and synaptic plasticity in mice with depressive-like behaviors

    Directory of Open Access Journals (Sweden)

    Xie Yongling

    2012-02-01

    Full Text Available Abstract Background Nanomaterials, as a new kind of materials, have been greatly applied in different fields due to their special properties. With the industrialization of nanostructured materials and increasing public exposure, the biosafety and potential influences on central nervous system (CNS have received more attention. Nanosized zinc oxide (nanoZnO was suggested to up-regulate neuronal excitability and to induce glutamate release in vitro. Therefore, we hypothesized nanoparticles of nanoZnO may lead to changes in balance of neurotransmitter or neuronal excitability of CNS. This study was to investigate if there were effects of nanoZnO on animal model of depression. Methods Male Swiss mice were given lipopolysaccharides (LPS, 100 μg/kg, 100 μg/ml, every other day, 8 times, i.p. from weaning to induce depressive-like behaviors. NanoZnO (5.6 mg/kg, 5.6 mg/ml, every other day, 8 times, i.p. was given as the interaction. The mouse model was characterized using the methods of open field test, tail suspension test and forced swim test. Furthermore, the spatial memory was evaluated using Morris water maze (MWM and the synaptic plasticity was assessed by measuring the long-term potentiation (LTP in the perforant pathway (PP to dentate gyrus (DG in vivo. Results Results indicated that model mice showed disrupted spatial memory and LTP after LPS injections and the behavioral and electrophysiological improvements after nanoZnO treatment. Conclusion Data suggested that nanoZnO may play some roles in CNS of mental disorders, which could provide some useful direction on the new drug exploring and clinical researches.

  19. Optimization of the Production Mixture of Selected Raw Material for Plastic Production: A Case Study of Louis Carter Plastic Manufacturing Industry

    Directory of Open Access Journals (Sweden)

    Okolie Paul Chukwulozie

    2015-11-01

    Full Text Available Statistical experiment design and analysis tools for the production have being developed specifically for the purpose of optimizing mixes, such as plastic products, in which the final product properties depend on the relative proportions of the components rather than their absolute amounts. Although mixture methods have been used in industries to develop products such as gasoline, metal alloys, detergents and foods, they have seen little application in the plastic industry. This paper describes an analysis in which a statistical mixture design tool called response surface design optimization tool was used to optimize the six mixture components of 25mm waste pipe, in order to obtain the optimal mixture ratio and their corresponding product yield. The results obtained show an optimal mixture ratio of PVC (45442.820, Stabilizer (1514.760, Calcium carbonate (0.0, Steric acid (151.480, Titanium (12.120, and Pigment (1.4079 for 25mm waste pipe. The optimal yield and composite desirability for 25mm waste pipe are 51990kg and 0.99990. The objective of the study from the result above was to reduce the wastage of raw materials, so as to increase the profitability of the final products. In addition, the model in use is recommended to the case company for effective utilisation of their various raw material mixes so as to obtain various optimal solutions of their raw materials mix and their various production yields.

  20. Identification and quantification of oligomers as potential migrants in plastics food contact materials with a focus in polycondensates - A review

    NARCIS (Netherlands)

    Hoppe, M.; de Voogt, P.; Franz, R.

    2016-01-01

    Background: Over the last years the variety of food and beverage packaging has increased with the development of new plastic materials and (co)polymer modifications. Oligomers which are always present in polymers evoke attention as potential migrants, from a qualitatively and quantitatively viewpoin

  1. Micro and nanopatterning of functional materials on flexible plastic substrates via site-selective surface modification using oxygen plasma

    NARCIS (Netherlands)

    George, A.; Stawski, T.M.; Unnikrishnan, S.; Veldhuis, S.A.; Elshof, J.E. ten

    2012-01-01

    A simple and cost effective methodology for large area micro and nanopatterning of a wide range of functional materials on flexible substrates is presented. A hydrophobic-hydrophilic chemical contrast was patterned on surfaces of various flexible plastic substrates using molds and shadow masks with

  2. Micro and nanopatterning of functional materials on flexible plastic substrates via site-selective surface modification using oxygen plasma

    NARCIS (Netherlands)

    George, A.; Stawski, T.M.; Unnikrishnan, S.; Veldhuis, S.A.; Elshof, J.E. ten

    2012-01-01

    A simple and cost effective methodology for large area micro and nanopatterning of a wide range of functional materials on flexible substrates is presented. A hydrophobic-hydrophilic chemical contrast was patterned on surfaces of various flexible plastic substrates using molds and shadow masks with

  3. Micro- and nanopatterning of functional materials on flexible plastic substrates via site-selective surface modification using oxygen plasma

    NARCIS (Netherlands)

    George, A.; Stawski, T.M.; Unnikrishnan, S.; Veldhuis, S.A.; Elshof, ten J.E.

    2012-01-01

    A simple and cost effective methodology for large area micro and nanopatterning of a wide range of functional materials on flexible substrates is presented. A hydrophobic-hydrophilic chemical contrast was patterned on surfaces of various flexible plastic substrates using molds and shadow masks with

  4. A new numerical method for determining collapse load-carrying capacity of structure made of elasto-plastic material

    Institute of Scientific and Technical Information of China (English)

    钟志鹏; 任大龙; 万水

    2014-01-01

    Determination of collapse load-carrying capacity of elasto-plastic material is very important in designing structure. The problem is commonly solved by elasto-plastic finite element method (FEM). In order to deal with material nonlinear problem involving strain softening problem effectively, a new numerical method-damped Newton method was proposed. The iterative schemes are discussed in detail for pure equilibrium models. In the equilibrium model, the plasticity criterion and the compatibility of the strains are verified, and the strain increment and plastic factor are treated as independent unknowns. To avoid the stiffness matrix being singularity or condition of matrix being ill, a damping factor α was introduced to adjust the value of plastic consistent parameter automatically during the iterations. According to the algorithm, the nonlinear finite element program was complied and its numerical example was calculated. The numerical results indicate that this method converges very fast for both small load steps and large load steps. Compared with those results obtained by analysis and experiment, the predicted ultimate bearing capacity from the proposed method is identical.

  5. Nicotine Modifies Corticostriatal Plasticity and Amphetamine Rewarding Behaviors in Mice123

    Science.gov (United States)

    Storey, Granville P.; Heimbigner, Lauren; Walwyn, Wendy M.; Bamford, Nigel S.

    2016-01-01

    Abstract Corticostriatal signaling participates in sensitized responses to drugs of abuse, where short-term increases in dopamine availability provoke persistent, yet reversible, changes in glutamate release. Prior studies in mice show that amphetamine withdrawal promotes a chronic presynaptic depression in glutamate release, whereas an amphetamine challenge reverses this depression by potentiating corticostriatal activity in direct pathway medium spiny neurons. This synaptic plasticity promotes corticostriatal activity and locomotor sensitization through upstream changes in the activity of tonically active cholinergic interneurons (ChIs). We used a model of operant drug-taking behaviors, in which mice self-administered amphetamine through an in-dwelling catheter. Mice acquired amphetamine self-administration under fixed and increasing schedules of reinforcement. Following a period of abstinence, we determined whether nicotinic acetylcholine receptors modified drug-seeking behavior and associated alterations in ChI firing and corticostriatal activity. Mice responding to conditioned reinforcement showed reduced ChI and corticostriatal activity ex vivo, which paradoxically increased following an amphetamine challenge. Nicotine, in a concentration that increases Ca2+ influx and desensitizes α4β2*-type nicotinic receptors, reduced amphetamine-seeking behaviors following abstinence and amphetamine-induced locomotor sensitization. Nicotine blocked the depression of ChI firing and corticostriatal activity and the potentiating response to an amphetamine challenge. Together, these results demonstrate that nicotine reduces reward-associated behaviors following repeated amphetamine and modifies the changes in ChIs firing and corticostriatal activity. By returning glutamatergic activity in amphetamine self-administering mice to a more stable and normalized state, nicotine limits the depression of striatal activity in withdrawal and the increase in activity following

  6. Nicotine Modifies Corticostriatal Plasticity and Amphetamine Rewarding Behaviors in Mice(1,2,3).

    Science.gov (United States)

    Storey, Granville P; Gonzalez-Fernandez, Gabriel; Bamford, Ian J; Hur, Matthew; McKinley, Jonathan W; Heimbigner, Lauren; Minasyan, Ani; Walwyn, Wendy M; Bamford, Nigel S

    2016-01-01

    Corticostriatal signaling participates in sensitized responses to drugs of abuse, where short-term increases in dopamine availability provoke persistent, yet reversible, changes in glutamate release. Prior studies in mice show that amphetamine withdrawal promotes a chronic presynaptic depression in glutamate release, whereas an amphetamine challenge reverses this depression by potentiating corticostriatal activity in direct pathway medium spiny neurons. This synaptic plasticity promotes corticostriatal activity and locomotor sensitization through upstream changes in the activity of tonically active cholinergic interneurons (ChIs). We used a model of operant drug-taking behaviors, in which mice self-administered amphetamine through an in-dwelling catheter. Mice acquired amphetamine self-administration under fixed and increasing schedules of reinforcement. Following a period of abstinence, we determined whether nicotinic acetylcholine receptors modified drug-seeking behavior and associated alterations in ChI firing and corticostriatal activity. Mice responding to conditioned reinforcement showed reduced ChI and corticostriatal activity ex vivo, which paradoxically increased following an amphetamine challenge. Nicotine, in a concentration that increases Ca(2+) influx and desensitizes α4β2*-type nicotinic receptors, reduced amphetamine-seeking behaviors following abstinence and amphetamine-induced locomotor sensitization. Nicotine blocked the depression of ChI firing and corticostriatal activity and the potentiating response to an amphetamine challenge. Together, these results demonstrate that nicotine reduces reward-associated behaviors following repeated amphetamine and modifies the changes in ChIs firing and corticostriatal activity. By returning glutamatergic activity in amphetamine self-administering mice to a more stable and normalized state, nicotine limits the depression of striatal activity in withdrawal and the increase in activity following abstinence and

  7. Reactive oxygen species mediate visceral pain-related amygdala plasticity and behaviors.

    Science.gov (United States)

    Ji, Guangchen; Li, Zhen; Neugebauer, Volker

    2015-05-01

    Accumulating evidence suggests an important contribution of reactive oxygen species (ROS) to pain and neuropsychiatric disorders, but their role in pain-related plasticity in the brain is largely unknown. Neuroplasticity in the central nucleus of the amygdala (CeA) correlates positively with pain behaviors in different models. Little is known, however, about mechanisms of visceral pain-related amygdala changes. The electrophysiological and behavioral studies reported here addressed the role of ROS in the CeA in a visceral pain model induced by intracolonic zymosan. Vocalizations to colorectal distension and anxiety-like behavior increased after intracolonic zymosan and were inhibited by intra-CeA application of a ROS scavenger (tempol, a superoxide dismutase mimetic). Tempol also induced a place preference in zymosan-treated rats but not in controls. Single-unit recordings of CeA neurons in anesthetized rats showed increases of background activity and responses to visceral stimuli after intracolonic zymosan. Intra-CeA application of tempol inhibited the increased activity but had no effect under normal conditions. Whole-cell patch-clamp recordings of CeA neurons in brain slices from zymosan-treated rats showed that tempol decreased neuronal excitability and excitatory synaptic transmission of presumed nociceptive inputs from the brainstem (parabrachial area) through a combination of presynaptic and postsynaptic actions. Tempol had no effect in brain slices from sham controls. The results suggest that ROS contribute to visceral pain-related hyperactivity of amygdala neurons and amygdala-dependent behaviors through a mechanism that involves increased excitatory transmission and excitability of CeA neurons.

  8. Synaptic plasticity in a recurrent neural network for versatile and adaptive behaviors of a walking robot.

    Science.gov (United States)

    Grinke, Eduard; Tetzlaff, Christian; Wörgötter, Florentin; Manoonpong, Poramate

    2015-01-01

    Walking animals, like insects, with little neural computing can effectively perform complex behaviors. For example, they can walk around their environment, escape from corners/deadlocks, and avoid or climb over obstacles. While performing all these behaviors, they can also adapt their movements to deal with an unknown situation. As a consequence, they successfully navigate through their complex environment. The versatile and adaptive abilities are the result of an integration of several ingredients embedded in their sensorimotor loop. Biological studies reveal that the ingredients include neural dynamics, plasticity, sensory feedback, and biomechanics. Generating such versatile and adaptive behaviors for a many degrees-of-freedom (DOFs) walking robot is a challenging task. Thus, in this study, we present a bio-inspired approach to solve this task. Specifically, the approach combines neural mechanisms with plasticity, exteroceptive sensory feedback, and biomechanics. The neural mechanisms consist of adaptive neural sensory processing and modular neural locomotion control. The sensory processing is based on a small recurrent neural network consisting of two fully connected neurons. Online correlation-based learning with synaptic scaling is applied to adequately change the connections of the network. By doing so, we can effectively exploit neural dynamics (i.e., hysteresis effects and single attractors) in the network to generate different turning angles with short-term memory for a walking robot. The turning information is transmitted as descending steering signals to the neural locomotion control which translates the signals into motor actions. As a result, the robot can walk around and adapt its turning angle for avoiding obstacles in different situations. The adaptation also enables the robot to effectively escape from sharp corners or deadlocks. Using backbone joint control embedded in the the locomotion control allows the robot to climb over small obstacles

  9. Stress and the Adolescent Brain: Plasticity of Reproductive Behaviors in Female

    Directory of Open Access Journals (Sweden)

    Farideh Zafari Zangeneh

    2009-03-01

    Full Text Available Early life events influence life-long patterns of emotionality and stress responsiveness and alter the rate of brain and body aging.  Much research attention has focused on the programming effects of the hypothalamus pituitary axis (HPA in early life and on understanding HPA function in response to stressors in adulthood. In comparison, there has been relatively little research on adolescence, a time of significant brain development particularly in the frontal lobe and a time which is of great importance for mental and physical health. The hippocampus, amygdala, and prefrontal cortex undergo stress-induced structural remodeling, which alters behavioral and physiological responses. During adolescence, HPA function is characterized by a prolonged activation in response to stressors compared to adulthood, which may render ongoing development of the brain vulnerable. Stress reactivity is markedly influenced by both the pubertal maturation and the experience of the individual. The frequency of the pulses is increased in chronic stress, since the neuroendocrine system is such a good candidate for mediators of many diseases linked to chronic stress. The activity of HPA axis  in life time of female,  sex maturity, pregnancy or lactation is a plasticity of the diurnal rhythm of pulse amplitude; chronic stress can change this program for   formation disorder in behavioral and physiological responses.

  10. Modeling activity-dependent plasticity in BCM spiking neural networks with application to human behavior recognition.

    Science.gov (United States)

    Meng, Yan; Jin, Yaochu; Yin, Jun

    2011-12-01

    Spiking neural networks (SNNs) are considered to be computationally more powerful than conventional NNs. However, the capability of SNNs in solving complex real-world problems remains to be demonstrated. In this paper, we propose a substantial extension of the Bienenstock, Cooper, and Munro (BCM) SNN model, in which the plasticity parameters are regulated by a gene regulatory network (GRN). Meanwhile, the dynamics of the GRN is dependent on the activation levels of the BCM neurons. We term the whole model "GRN-BCM." To demonstrate its computational power, we first compare the GRN-BCM with a standard BCM, a hidden Markov model, and a reservoir computing model on a complex time series classification problem. Simulation results indicate that the GRN-BCM significantly outperforms the compared models. The GRN-BCM is then applied to two widely used datasets for human behavior recognition. Comparative results on the two datasets suggest that the GRN-BCM is very promising for human behavior recognition, although the current experiments are still limited to the scenarios in which only one object is moving in the considered video sequences.

  11. The Activation Energy Of Ignition Calculation For Materials Based On Plastics

    OpenAIRE

    Rantuch Peter; Wachter Igor; Martinka Jozef; Kuracina Marcel

    2015-01-01

    This article deals with the activation energy of ignition calculation of plastics. Two types of polyamide 6 and one type of polypropylene and polyurethane were selected as samples. The samples were tested under isothermal conditions at several temperatures while times to ignition were observed. From the obtained data, activation energy relating to the moment of ignition was calculated for each plastics. The values for individual plastics were different. The highest activation energies (129.5 ...

  12. Enhancement of extinction learning attenuates ethanol-seeking behavior and alters plasticity in the prefrontal cortex.

    Science.gov (United States)

    Gass, Justin T; Trantham-Davidson, Heather; Kassab, Amanda S; Glen, William B; Olive, M Foster; Chandler, L Judson

    2014-05-28

    Addiction is a chronic relapsing disorder in which relapse is often initiated by exposure to drug-related cues. The present study examined the effects of mGluR5 activation on extinction of ethanol-cue-maintained responding, relapse-like behavior, and neuronal plasticity. Rats were trained to self-administer ethanol and then exposed to extinction training during which they were administered either vehicle or the mGluR5 positive allosteric modulator 3-cyano-N-(1,3-diphenyl-1H-pyrazol-5-yl) or CDPPB. CDPPB treatment reduced active lever responding during extinction, decreased the total number of extinction sessions required to meet criteria, and attenuated cue-induced reinstatement of ethanol seeking. CDPPB facilitation of extinction was blocked by the local infusion of the mGluR5 antagonist 3-((2-methyl-4-thiazolyl)ethynyl) pyridine into the infralimbic (IfL) cortex, but had no effect when infused into the prelimbic (PrL) cortex. Analysis of dendritic spines revealed alterations in structural plasticity, whereas electrophysiological recordings demonstrated differential alterations in glutamatergic neurotransmission in the PrL and IfL cortex. Extinction was associated with increased amplitude of evoked synaptic PrL and IfL NMDA currents but reduced amplitude of PrL AMPA currents. Treatment with CDPPB prevented the extinction-induced enhancement of NMDA currents in PrL without affecting NMDA currents in the IfL. Whereas CDPPB treatment did not alter the amplitude of PrL or IfL AMPA currents, it did promote the expression of IfL calcium-permeable GluR2-lacking receptors in both abstinence- and extinction-trained rats, but had no effect in ethanol-naive rats. These results confirm changes in the PrL and IfL cortex in glutamatergic neurotransmission during extinction learning and demonstrate that manipulation of mGluR5 facilitates extinction of ethanol cues in association with neuronal plasticity.

  13. Cytotoxicity, Biocompatibility, and Biomineralization of the New High-plasticity MTA Material.

    Science.gov (United States)

    Cintra, Luciano Tavares Angelo; Benetti, Francine; de Azevedo Queiroz, Índia Olinta; de Araújo Lopes, Juliana Maria; Penha de Oliveira, Sandra Helena; Sivieri Araújo, Gustavo; Gomes-Filho, João Eduardo

    2017-05-01

    Mineral trioxide aggregate (MTA) has excellent biological properties, but its handling properties have been criticized for both ProRoot MTA (Tulsa Dental Products, Tulsa, OK) and white MTA-Angelus (MTA-Ang; Angelus Indústria de Produtos Odontológicos S/A, Londrina, PR, Brazil). Angelus MTA HP (high plasticity) (Angelus Indústria de Produtos Odontológicos S/A) has been introduced recently. Considering the importance of biological properties of materials that will be in contact with the tissues, this study evaluated the cytotoxicity, biocompatibility, and biomineralization of MTA HP compared with white MTA-Ang. L929 fibroblast cell lines were cultured, and cell viability was assessed at 6, 24, 48, and 72 hours using the alamar Blue assay (Thermo Fisher Scientific, Waltham, MA). A subcutaneous implant test was performed with polyethylene tubes containing 1 of the materials or empty tubes (control) using 20 Wistar rats. After 7 and 30 days of implantation, the tubes with surrounding tissues were removed for analysis using hematoxylin-eosin or von Kossa stain or they remained unstained for observation under polarized light. The results were statistically analyzed (P MTA HP was observed after 24, 48, and 72 hours compared with the control (P MTA HP exhibited a higher viability compared with white MTA-Ang (P  .05). At 30 days, mild inflammation and a thin fibrous capsule were observed in all groups (P > .05). All materials had structures positive for von Kossa and birefringent to polarized light. MTA HP showed biocompatibility and biomineralization similar to MTA-Ang. In addition, MTA HP showed increased fibroblast cell viability compared with white MTA-Ang after a longer period. Copyright © 2017 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  14. Heterogeneities in local plastic flow behavior in a dissimilar weld between low-alloy steel and stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Mas, Fanny [Université Grenoble Alpes, SIMAP, 38000 Grenoble (France); CNRS, SIMAP, 38000 Grenoble (France); Martin, Guilhem, E-mail: guilhem.martin@simap.grenoble-inp.fr [Université Grenoble Alpes, SIMAP, 38000 Grenoble (France); CNRS, SIMAP, 38000 Grenoble (France); Lhuissier, Pierre; Bréchet, Yves; Tassin, Catherine [Université Grenoble Alpes, SIMAP, 38000 Grenoble (France); CNRS, SIMAP, 38000 Grenoble (France); Roch, François [Areva NP, Tour Areva, 92084 Paris La Défense (France); Todeschini, Patrick [EDF R& D, Avenue des Renardières, 77250 Moret-sur-Loing (France); Simar, Aude [Institute of Mechanics, Materials and Civil Engineering (iMMC), Université catholique de Louvain, 1348 Louvain-la-Neuve (Belgium)

    2016-06-14

    In dissimilar welds between low-alloy steel and stainless steel, the post-weld heat-treatment results in a high variety of microstructures coexisting around the fusion line, due to carbon diffusion and carbides dissolution/precipitation. The local constitutive laws in the vicinity of the fusion zone were identified by micro tensile specimens for the sub-millimeter sized zones, equivalent bulk materials representing the decarburized layer using both wet H{sub 2} atmosphere and diffusion couple, and nano-indentation for the carburized regions (i.e. the martensitic band and the austenitic region). The decarburized zone presents only 50% of the yield strength of the low-alloy steel heat affected zone and a ductility doubled. The carburized zones have a yield strength 3–5 times higher than that of the low-alloy steel heat affected zone and have almost no strain hardening capacity. These properties result in heterogeneous plastic deformation happening over only millimeters when the weld is loaded perpendicularly to the weld line, affecting its overall behavior. The constitutive laws experimentally identified were introduced as inputs into a finite elements model of the transverse tensile test performed on the whole dissimilar weld. A good agreement between experiments and simulations was achieved on the global stress-strain curve. The model also well predicts the local strain field measured by microscale DIC. A large out-of-plane deformation due to the hard carburized regions has also been identified.

  15. Microstructure Evolution and Mechanical Behavior of a Hot-Rolled High-Manganese Dual-Phase Transformation-Induced Plasticity/Twinning-Induced Plasticity Steel

    Science.gov (United States)

    Fu, Liming; Shan, Mokun; Zhang, Daoda; Wang, Huanrong; Wang, Wei; Shan, Aidang

    2017-05-01

    The microstructures and deformation behavior were studied in a high-temperature annealed high-manganese dual-phase (28 vol pct δ-ferrite and 72 vol pct γ-austenite) transformation-induced plasticity/twinning-induced plasticity (TRIP/TWIP) steel. The results showed that the steel exhibits a special Lüders-like yielding phenomenon at room temperature (RT) and 348 K (75 °C), while it shows continuous yielding at 423 K, 573 K and 673 K (150 °C, 300 °C and 400 °C) deformation. A significant TRIP effect takes place during Lüders-like deformation at RT and 348 K (75 °C) temperatures. Semiquantitative analysis of the TRIP effect on the Lüders-like yield phenomenon proves that a softening effect of the strain energy consumption of strain-induced transformation is mainly responsible for this Lüders-like phenomenon. The TWIP mechanism dominates the 423 K (150 °C) deformation process, while the dislocation glide controls the plasticity at 573 K (300 °C) deformation. The delta-ferrite, as a hard phase in annealed dual-phase steel, greatly affects the mechanical stability of austenite due to the heterogeneous strain distribution between the two phases during deformation. A delta-ferrite-aided TRIP effect, i.e., martensite transformation induced by localized strain concentration of the hard delta-ferrite, is proposed to explain this kind of Lüders-like phenomenon. Moreover, the tensile curve at RT exhibits an upward curved behavior in the middle deformation stage, which is principally attributed to the deformation twinning of austenite retained after Lüders-like deformation. The combination of the TRIP effect during Lüders-like deformation and the subsequent TWIP effect greatly enhances the ductility in this annealed high-manganese dual-phase TRIP/TWIP steel.

  16. Microstructure Evolution and Mechanical Behavior of a Hot-Rolled High-Manganese Dual-Phase Transformation-Induced Plasticity/Twinning-Induced Plasticity Steel

    Science.gov (United States)

    Fu, Liming; Shan, Mokun; Zhang, Daoda; Wang, Huanrong; Wang, Wei; Shan, Aidang

    2017-02-01

    The microstructures and deformation behavior were studied in a high-temperature annealed high-manganese dual-phase (28 vol pct δ-ferrite and 72 vol pct γ-austenite) transformation-induced plasticity/twinning-induced plasticity (TRIP/TWIP) steel. The results showed that the steel exhibits a special Lüders-like yielding phenomenon at room temperature (RT) and 348 K (75 °C), while it shows continuous yielding at 423 K, 573 K and 673 K (150 °C, 300 °C and 400 °C) deformation. A significant TRIP effect takes place during Lüders-like deformation at RT and 348 K (75 °C) temperatures. Semiquantitative analysis of the TRIP effect on the Lüders-like yield phenomenon proves that a softening effect of the strain energy consumption of strain-induced transformation is mainly responsible for this Lüders-like phenomenon. The TWIP mechanism dominates the 423 K (150 °C) deformation process, while the dislocation glide controls the plasticity at 573 K (300 °C) deformation. The delta-ferrite, as a hard phase in annealed dual-phase steel, greatly affects the mechanical stability of austenite due to the heterogeneous strain distribution between the two phases during deformation. A delta-ferrite-aided TRIP effect, i.e., martensite transformation induced by localized strain concentration of the hard delta-ferrite, is proposed to explain this kind of Lüders-like phenomenon. Moreover, the tensile curve at RT exhibits an upward curved behavior in the middle deformation stage, which is principally attributed to the deformation twinning of austenite retained after Lüders-like deformation. The combination of the TRIP effect during Lüders-like deformation and the subsequent TWIP effect greatly enhances the ductility in this annealed high-manganese dual-phase TRIP/TWIP steel.

  17. Modeling of plastic zones before the crack's peak of given structure constructional materials

    Directory of Open Access Journals (Sweden)

    Т.І. Матченко

    2005-01-01

    Full Text Available  The basic kinds of deformation in plastic zones near top of a crack are determined.Zones are determined, in which the sliding in crystals ,between grains sliding and plastic deformation of a continuous body is typical.

  18. Quality and safety aspects of reusable plastic food packaging materials: influence of reuse on intrinsic properties.

    Science.gov (United States)

    Jetten, J; de, Kruijf N

    2002-01-01

    The aim of the project was to develop a comprehensive package of quality assurance criteria for use by the industry and by regulatory authorities to ensure the quality and safety-in-use (sensory, microbiological and chemical safety) of reused plastics for food packaging. The paper describes the investigations into potential adulteration effects by reuse on the intrinsic properties of plastics in more detail. The plastic articles investigated were bottles of polyethylene terephthalate (PET) or polycarbonate (PC) and vending cups of polypropylene (PP). The influence of repeated use on the migration of plastic constituents, degradation products of plastic additives, barrier properties and surface characteristics were investigated. The overall conclusion was that the investigated intrinsic properties of the refillable articles were not significantly influenced by repeated use. Only the hydrophobicity of the refillable PC and PP articles seemed to be influenced by repeated washing. PC bottles washed 15 times were significantly less hydrophobic than unwashed bottles.

  19. Plastic Strain Induced Damage Evolution and Martensitic Transformation in Ductile Materials at Cryogenic Temperatures

    CERN Document Server

    Garion, C

    2002-01-01

    The Fe-Cr-Ni stainless steels are well known for their ductile behaviour at cryogenic temperatures. This implies development and evolution of plastic strain fields in the stainless steel components subjected to thermo-mechanical loads at low temperatures. The evolution of plastic strain fields is usually associated with two phenomena: ductile damage and strain induced martensitic transformation. Ductile damage is described by the kinetic law of damage evolution. Here, the assumption of isotropic distribution of damage (microcracks and microvoids) in the Representative Volume Element (RVE) is made. Formation of the plastic strain induced martensite (irreversible process) leads to the presence of quasi-rigid inclusions of martensite in the austenitic matrix. The amount of martensite platelets in the RVE depends on the intensity of the plastic strain fields and on the temperature. The evolution of the volume fraction of martensite is governed by a kinetic law based on the accumulated plastic strain. Both of thes...

  20. Nonminimum Phase Behavior of Laser Material Processing

    NARCIS (Netherlands)

    Römer, G.R.B.E.; Weerkamp, N.P.; Meijer, J.; Postma, S.

    2001-01-01

    Optical sensors are increasingly applied in laser material processing to monitor and control the lasermaterial interaction zone. Dynamic models, relating the sensor signals (e.g. as temperature or molten area) to the process inputs (e.g. laser power or beam velocity), provide the basis for the desig

  1. Micromechanical Behavior of Frictional Geologic Materials

    Science.gov (United States)

    1988-11-01

    ranging from a suspension of particles to multicontacted particles forming a material with continuous force-deformation characteristics, i.e., a...Vol. 14, No. 4, pp. 25-38 (1974). 15. Biarez, J., "Contribution a l’Etude des Proprietes Mecaniques des Sols et des Materiaux Pulverulents," These de

  2. Dynamic High-Pressure Behavior of Hierarchical Heterogeneous Geological Materials

    Science.gov (United States)

    2016-04-01

    pressure -density Hugoniot plots for simulations using the ‘mix 5’ option, as will be presented later. The volume weighted option for mixed cells (refered...AFRL-AFOSR-VA-TR-2016-0150 Dynamic High- Pressure Behavior of Geological Materials Naresh Thadhani GEORGIA TECH RESEARCH CORPORATION Final Report 04...31-12-2015 4.  TITLE AND SUBTITLE Dynamic High- Pressure Behavior of Hierarchical Heterogeneous Geological Materials 5a.  CONTRACT NUMBER 5b.  GRANT

  3. Plastic analysis of the crack problem in two-dimensional decagonal Al-Ni-Co quasicrystalline materials of point group 10,(10)

    Institute of Scientific and Technical Information of China (English)

    Li Wu; Fan Tian You

    2011-01-01

    The fundamental plastic nature of the quasicrystalline materials remains an open problem due to its essential complicacy. By developing the proposed generalized cohesive force model, the plastic deformation of crack in point group 10,10 decagonal quasicrystals is analysed strictly and systematically. The crack tip opening displacement (CTOD) and the size of the plastic zone around the crack tip are determined exactly. The quantity of the crack tip opening displacement can be used as a parameter of nonlinear fracture mechanics of quasicrystalline material. In addition, the present work may provide a way for the plastic analysis of quasicrystals.

  4. Numerical simulation of mechanical behavior of composite materials

    CERN Document Server

    Oller, Sergio

    2014-01-01

    An original mechanical formulation to treat nonlinear orthotropic behavior of composite materials is presented in this book. It also examines different formulations that allow us to evaluate the behavior of composite materials through the composition of its components, obtaining a new composite material. Also two multiple scale homogenization methods are given, one based on the analytical study of the cells (Ad-hoc homogenization), and other one, more general based on the finite element procedure applied on the macro scale (upper-scale) and in the micro scale (sub-scale). A very general formulation to simulate the mechanical behavior for traditional composite structures (plywood, reinforced concrete, masonry, etc.), as well as the new composite materials reinforced with long and short fibers, nanotubes, etc., are also shown in this work. Typical phenomena occurring in composite materials are also described in this work, including fiber-matrix debounding, local buckling of fibers and its coupling with the over...

  5. Sex Role Socialization Via Teachers' Behavior and Sexually Stereotyped Materials.

    Science.gov (United States)

    Snodgrass, Sara E.; And Others

    Research has shown that children's differentiation of gender-appropriate behavior is not directly affected by their teacher's gender. However, the teacher's behavior in relation to the material being taught may convey the sex-appropriateness or -inappropriateness to the child. To examine the effects of student gender and sexual stereotype of the…

  6. Fair Verbal Behavior: A Protocol Materials Unit for Teachers.

    Science.gov (United States)

    Mullis, Ina V. S.

    This protocol materials unit, based on the interaction component of instruction, is designed to help prospective teachers better understand verbal behaviors as related to fair (positive feedback) and unfair (negative feedback) responses. Fair verbal behavior is defined as following a standard of equal treatment toward all students and as free from…

  7. A strategy to modulate the electrophoretic behavior in plastic microchips using sodium polystyrene sulfonate.

    Science.gov (United States)

    Guo, Jinxiu; Chen, Yu; Zhao, Lizhi; Sun, Ping; Li, Hongli; Zhou, Lei; Wang, Xiayan; Pu, Qiaosheng

    2016-12-16

    Plastic microchips have been broadly used as disposable microfluidic devices, but the poorly defined surface properties limit their application. Herein, we proved that an anionic polymer could be used as the background electrolyte (BGE) to provide a strong and stable cathodic electroosmotic flow (EOF) and modulate the electrophoretic behavior for efficient separation in relative thicker microchannels (∼75μm id). A cathodic EOF of ∼3.3×10(-4)cm(2)V(-1)s(-1) was maintained using sodium polystyrene sulfonate (PSSNa) with a molecular weight of 5×10(5) as the BGE, which ensured fluorescein isothiocyanate labeled biogenic amines (BAs) appeared ahead of other components in the electropherograms obtained with microchips of cyclic olefin copolymer. Four selected BAs appeared within 50s and theoretical plate numbers of 8.0×10(5)/m were achieved. The role of PSSNa was evaluated with streaming potential, dynamic light scattering, contact angle and atomic force microscopy. Its functionalities as surface modifier, viscosity regulator and pseudostationary phase were also confirmed. The proposed electrophoretic method was applied in the fast determination of BAs in fish meat samples.

  8. Odor experiences during preimaginal stages cause behavioral and neural plasticity in adult honeybees

    Directory of Open Access Journals (Sweden)

    Gabriela eRamirez

    2016-06-01

    Full Text Available In eusocial insects, experiences acquired during the development have long-term consequences on mature behavior. In the honeybee that suffers profound changes associated with metamorphosis, the effect of odor experiences at larval instars on the subsequent physiological and behavioral response is still unclear. To address the impact of preimaginal experiences on the adult honeybee, colonies containing larvae were fed scented food. The effect of the preimaginal experiences with the food odor was assessed in learning performance, memory retention and generalization in 3-5- and 17-19-day-old bees, in the regulation of their expression of synaptic-related genes and in theperception and morphology of their antennae. Three-5 day old bees that experienced 1-hexanol (1-HEX as food scent responded more to the presentation of the odor during the 1-HEX conditioning than control bees (i.e. bees reared in colonies fed unscented food. Higher levels of PER to 1-HEX in this group also extent to HEXA, the most perceptually similar odor to the experienced one that we tested. These results were not observed for the group tested at older ages. In the brain of young adults, larval experiences triggered similar levels of neurexins and neuroligins expression, two proteins that have been involved in synaptic formation after associative learning. At the sensory periphery, the experience did not alter the number of the olfactory sensilla placoidea, but did reduce the electrical response of the antennae to the experienced and novel odor. Our study provides a new insight into the effects of preimaginal experiences in the honeybee and the mechanisms underlying olfactory plasticity at larval stage of holometabolous insects.

  9. Odor Experiences during Preimaginal Stages Cause Behavioral and Neural Plasticity in Adult Honeybees

    Science.gov (United States)

    Ramírez, Gabriela; Fagundez, Carol; Grosso, Juan P.; Argibay, Pablo; Arenas, Andrés; Farina, Walter M.

    2016-01-01

    In eusocial insects, experiences acquired during the development have long-term consequences on mature behavior. In the honeybee that suffers profound changes associated with metamorphosis, the effect of odor experiences at larval instars on the subsequent physiological and behavioral response is still unclear. To address the impact of preimaginal experiences on the adult honeybee, colonies containing larvae were fed scented food. The effect of the preimaginal experiences with the food odor was assessed in learning performance, memory retention and generalization in 3–5- and 17–19 day-old bees, in the regulation of their expression of synaptic-related genes and in the perception and morphology of their antennae. Three-five day old bees that experienced 1-hexanol (1-HEX) as food scent responded more to the presentation of the odor during the 1-HEX conditioning than control bees (i.e., bees reared in colonies fed unscented food). Higher levels of proboscis extension response (PER) to 1-HEX in this group also extended to HEXA, the most perceptually similar odor to the experienced one that we tested. These results were not observed for the group tested at older ages. In the brain of young adults, larval experiences triggered similar levels of neurexins (NRXs) and neuroligins (Nlgs) expression, two proteins that have been involved in synaptic formation after associative learning. At the sensory periphery, the experience did not alter the number of the olfactory sensilla placoidea, but did reduce the electrical response of the antennae to the experienced and novel odor. Our study provides a new insight into the effects of preimaginal experiences in the honeybee and the mechanisms underlying olfactory plasticity at larval stage of holometabolous insects. PMID:27375445

  10. Description of the M-integral in an elastic plastic material

    Science.gov (United States)

    Tao, Huiyu; Gao, Cheng; Xu, Jinyong; Tang, Yan; Cai, Dayong; Huang, Ranran

    2017-01-01

    By use of finite element analysis method of elastic-plasticity, a calculation of M-integral for 7075 aluminum alloy plate containing different configuration defects was conducted. The effect of plastic energy on path independence of the M-integral is discussed, The variation of M-integral of the holes before and after coalescence under tension loading is studied. Analysis result indicates that M-integral will be path dependent when the plastic zone is passed through by the selected integration contours. There is a jump of the M-integral when coalescence of the holes in a plate occurs. The value of the M-integral is always configuration dependent.

  11. The Activation Energy Of Ignition Calculation For Materials Based On Plastics

    Science.gov (United States)

    Rantuch, Peter; Wachter, Igor; Martinka, Jozef; Kuracina, Marcel

    2015-06-01

    This article deals with the activation energy of ignition calculation of plastics. Two types of polyamide 6 and one type of polypropylene and polyurethane were selected as samples. The samples were tested under isothermal conditions at several temperatures while times to ignition were observed. From the obtained data, activation energy relating to the moment of ignition was calculated for each plastics. The values for individual plastics were different. The highest activation energies (129.5 kJ.mol-1 and 106.2 kJ.mol-1) were achieved by polyamides 6, while the lowest was determined for a sample of polyurethane.

  12. The Activation Energy Of Ignition Calculation For Materials Based On Plastics

    Directory of Open Access Journals (Sweden)

    Rantuch Peter

    2015-06-01

    Full Text Available This article deals with the activation energy of ignition calculation of plastics. Two types of polyamide 6 and one type of polypropylene and polyurethane were selected as samples. The samples were tested under isothermal conditions at several temperatures while times to ignition were observed. From the obtained data, activation energy relating to the moment of ignition was calculated for each plastics. The values for individual plastics were different. The highest activation energies (129.5 kJ.mol−1 and 106.2 kJ.mol−1 were achieved by polyamides 6, while the lowest was determined for a sample of polyurethane.

  13. A sophisticated simulation for the fracture behavior of concrete material using XFEM

    Science.gov (United States)

    Zhai, Changhai; Wang, Xiaomin; Kong, Jingchang; Li, Shuang; Xie, Lili

    2017-07-01

    The development of a powerful numerical model to simulate the fracture behavior of concrete material has long been one of the dominant research areas in earthquake engineering. A reliable model should be able to adequately represent the discontinuous characteristics of cracks and simulate various failure behaviors under complicated loading conditions. In this paper, a numerical formulation, which incorporates a sophisticated rigid-plastic interface constitutive model coupling cohesion softening, contact, friction and shear dilatation into the XFEM, is proposed to describe various crack behaviors of concrete material. An effective numerical integration scheme for accurately assembling the contribution to the weak form on both sides of the discontinuity is introduced. The effectiveness of the proposed method has been assessed by simulating several well-known experimental tests. It is concluded that the numerical method can successfully capture the crack paths and accurately predict the fracture behavior of concrete structures. The infl uence of mode-II parameters on the mixed-mode fracture behavior is further investigated to better determine these parameters.

  14. Tunable plasticity in amorphous silicon carbide films.

    Science.gov (United States)

    Matsuda, Yusuke; Kim, Namjun; King, Sean W; Bielefeld, Jeff; Stebbins, Jonathan F; Dauskardt, Reinhold H

    2013-08-28

    Plasticity plays a crucial role in the mechanical behavior of engineering materials. For instance, energy dissipation during plastic deformation is vital to the sufficient fracture resistance of engineering materials. Thus, the lack of plasticity in brittle hybrid organic-inorganic glasses (hybrid glasses) often results in a low fracture resistance and has been a significant challenge for their integration and applications. Here, we demonstrate that hydrogenated amorphous silicon carbide films, a class of hybrid glasses, can exhibit a plasticity that is even tunable by controlling their molecular structure and thereby leads to an increased and adjustable fracture resistance in the films. We decouple the plasticity contribution from the fracture resistance of the films by estimating the "work-of-fracture" using a mean-field approach, which provides some insight into a potential connection between the onset of plasticity in the films and the well-known rigidity percolation threshold.

  15. Alteration of Cingulate Long-Term Plasticity and Behavioral Sensitization to Inflammation by Environmental Enrichment

    Science.gov (United States)

    Shum, Fanny W. F.; Wu, Long-Jun; Zhao, Ming-Gao; Toyoda, Hiroki; Xu, Hui; Ren, Ming; Pinaud, Raphael; Ko, Shanelle W.; Lee, Yong-Seok; Kaang, Bong-Kiun; Zhuo, Min

    2007-01-01

    Exposure to an enriched environment (EE) has been shown to induce cortical plasticity. Considerable amount of research is focused on the effects of EE in the hippocampus; however, effects of EE on other brain regions and the mechanisms involved are not well known. To investigate this, we induced cortical plasticity by placing mice in an EE for one…

  16. Evaluation of plastic materials for range shifting, range compensation, and solid-phantom dosimetry for carbon-ion beams

    CERN Document Server

    Kanematsu, Nobuyuki; Ogata, Risa

    2012-01-01

    Purpose: Beam range control is the essence of radiotherapy with heavy charged particles. In conventional broad-beam delivery, fine range adjustment is achieved by insertion of range shifting and compensating materials. Ideally, such material should be water equivalent as well as that for dosimetry. In this study, we evaluated dosimetric water equivalency of four common plastics, HDPE, PMMA, PET, and POM, by uniformity of effective densities for carbon-ion-beam interactions. Methods: Using the Bethe formula for stopping, the Gottschalk formula for multiple scattering, and the Sihver formula for nuclear interactions, we calculated the effective densities of the plastics for these interactions. We tested HDPE, PMMA, and POM in carbon-ion-beam experiment and measured attenuations of carbon ions, which were compared with empirical linear-attenuation-model calculations. Results: The theoretical calculations resulted in reduced multiple scattering and increased nuclear interactions for HDPE compared to water, which ...

  17. Highly plastic behavior and fluidization of gouge; implications for fault and landslide mechanics and for the generation of mud volcanoes

    Science.gov (United States)

    Shimamoto, Toshihiko; Aoki, Kazuhiro; Seshimo, Kazuyoshi; Hu, Wei; Ma, Shengli; Yao, Lu; Xiong, Ran; Xiao, Yinke

    2016-04-01

    We address an issue on "how low gouge friction can be with an increasing amount of pore fluid" (an unexplored problem in fault mechanics), as studied with a rotary-shear low to high-velocity friction apparatus in Beijing using host specimens of Ti-Al-V alloy with a Teflon sleeve. A friction experiment was conducted on about 1 mm-thick, smectite-rich gouge from Shionohira fault zone, Fukushima, Japan, with 80 wt% of initial pore water, at a normal stress of 1 MPa, and with velocity steps of 17 times ranging in 0.21 microns/s to 2.1 m/s. Friction coefficients at slow rates were initially 0.003 to 0.005 with abundant water, but the coefficients increased to about 0.2 owing to the loss of water during the drained tests. Gouge was squeezed out slowly from host-specimen/Teflon interface as very thin paper-like flakes during a part of the run, indicating highly plastic behavior of gouge. The initial friction was by far the lowest ever reported! A dry high-velocity friction experiment on the same gouge (normal stress 2 MPa, velocity 2.1 m/s) revealed fluidization of gouge due to vaporized water released during decomposition of clay minerals. Friction coefficient increased to its peak (~ 0.8), followed by nearly exponential decay to a steady-state value of ~ 0.2. Then the friction coefficient began to decrease almost linearly with displacement down to ca. 0.07, deviating from an exponential decay. The gouge was lost almost instantly in less than one second, terminating the run. Temperature, measured at the sliding surface, began to decrease at the onset of the nearly linear weakening, strongly suggesting dehydration of clays (endothermic reactions). We interpret the results that steam pressure increased in gouge till a limit to cause a small explosion of gouge. Gouge can fluidize! A series of low to intermediate-velocity experiments on slip-zone materials from Kualiangzi landslide, Sichuan, China, demonstrated that the initial friction coefficient was less than 0.1 with a

  18. The effect of inclination angle on the plastic deformation behavior of bicrystalline silver nanowires with Σ3 asymmetric tilt grain boundaries

    Science.gov (United States)

    Yuan, Lin; Jing, Peng; Shan, Debin; Guo, Bin

    2017-01-01

    Atomistic simulations were used to investigate the plastic deformation behavior of bicrystalline silver nanowires with Σ3 asymmetric tilt grain boundaries at 0.1 K. The calculated grain boundary energies of Σ3 asymmetric tilt grain boundaries corresponded well with the energies measured in experiments and predicted by the theoretical description. The Σ3 asymmetric tilt grain boundaries with low inclination angles were composed of a replication of twin boundary segments separated by small ledges. The results demonstrated that the combination effect of Schmid factor and non-Schmid factors could explain dislocations emission into grain 1 only in models with low inclination angles (Ф nanocrystalline materials and provide insights into the synthesis of nanocrystalline materials with superior strength and ductility.

  19. Environmental risk and influence of chemicals from plastic materials on children’s health – the challenge also for paediatricians

    OpenAIRE

    Zbigniew Rudkowski

    2013-01-01

    Chemicals artificially synthesized and leaching into a common environment are a toxicological risk particularly in prenatal period and in early childhood. The risk exists due to the contact with xenogenic substances from maternal breast milk and other food, polluted air and water, plastic materials, cosmetics. All endocrine and neurological disruptors (EDC) pass across placenta, then can cause hormonal, neurological or metabolic disorders mainly due to estrogenic actio...

  20. Evaluation of plastic materials for range shifting, range compensation, and solid-phantom dosimetry in carbon-ion radiotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Kanematsu, Nobuyuki; Koba, Yusuke; Ogata, Risa [Research Center for Charged Particle Therapy, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555 (Japan)

    2013-04-15

    Purpose: Beam range control is the essence of radiotherapy with heavy charged particles. In conventional broad-beam delivery, fine range adjustment is achieved by insertion of range shifting and compensating materials. In dosimetry, solid phantoms are often used for convenience. These materials should ideally be equivalent to water. In this study, the authors evaluated dosimetric water equivalence of four common plastics, high-density polyethylene (HDPE), polymethyl methacrylate (PMMA), polyethylene terephthalate (PET), and polyoxymethylene (POM). Methods: Using the Bethe formula for energy loss, the Gottschalk formula for multiple scattering, and the Sihver formula for nuclear interactions, the authors calculated the effective densities of the plastics for these interactions. The authors experimentally measured variation of the Bragg peak of carbon-ion beams by insertion of HDPE, PMMA, and POM, which were compared with analytical model calculations. Results: The theoretical calculation resulted in slightly reduced multiple scattering and severely increased nuclear interactions for HDPE, compared to water and the other plastics. The increase in attenuation of carbon ions for 20-cm range shift was experimentally measured to be 8.9% for HDPE, 2.5% for PMMA, and 0.0% for POM while PET was theoretically estimated to be in between PMMA and POM. The agreement between the measurements and the calculations was about 1% or better. Conclusions: For carbon-ion beams, POM was dosimetrically indistinguishable from water and the best of the plastics examined in this study. The poorest was HDPE, which would reduce the Bragg peak by 0.45% per cm range shift, although with marginal superiority for reduced multiple scattering. Between the two clear plastics, PET would be superior to PMMA in dosimetric water equivalence.

  1. Low temperature creep plasticity

    Directory of Open Access Journals (Sweden)

    Michael E. Kassner

    2014-07-01

    Full Text Available The creep behavior of crystalline materials at low temperatures (T < 0.3Tm is discussed. In particular, the phenomenological relationships that describe primary creep are reviewed and analyzed. A discussion of the activation energy for creep at T < 0.3Tm is discussed in terms of the context of higher temperature activation energy. The basic mechanism(s of low temperature creep plasticity are discussed, as well.

  2. Experimental Studies on the Bonding Strength and Fracture Behavior of Incompatible Materials Bonded by Mechanical Adhesion in Multilayer Rotational Molding

    Directory of Open Access Journals (Sweden)

    Martin Löhner

    2016-01-01

    Full Text Available Rotational molding is a plastic processing method that allows for the production of seamless, hollow parts. Defined shaping of the polymeric material only takes place on the outer surface where contact to the tooling is given. The inner surface forms by surface tension effects. By sequential adding of materials, complex multilayer build-up is possible. Besides pure, single materials, filled, or multiphase systems can be processed as well. In this work, possibilities to generate bonding between supposedly incompatible materials by adding a mix-material interlayer are investigated. Interlock mechanisms on a microscale dimension occur and result in mechanical bonding between the used materials, polyethylene (PE and thermoplastic polyurethane (TPE-U. The bonding strength between the materials was investigated to reveal the correlations between processing parameters, resulting layer build-up, and bonding strength. The failure behavior was analyzed and inferences to the influence of the varied parameters were drawn.

  3. Plasticized Effect of Plasticizers on CPE Waterproofing Materials%增塑剂对氯化聚乙烯防水卷材增塑效果的研究

    Institute of Scientific and Technical Information of China (English)

    王新星; 苑会林; 李明昆

    2012-01-01

    分析了几种增塑剂[邻苯二甲酸二丁酯(DBP)、邻苯二甲酸二辛酯(DOP)、邻苯二甲酸二异癸酯(DIDP)、癸二酸二辛酯(DOS)、偏苯三甲酸三辛酯(TOTM)以及氯化石蜡等]对氯化聚乙烯(CPE)防水卷材的增塑机理.在保持其他条件不变的前提下,选取增塑剂的份数为25份,并在此基础上从力学性能、耐温性能、流变性能以及微观结构四个方面比较各种增塑剂与CPE树脂的相容性,从而比较它们的增塑效果.结果表明:DSC以及电镜结果显示邻苯类增塑剂效果明显优于其他类型增塑剂;其中DOP为主增塑剂的体系综合性能最好;DOS作为主增塑剂时具有良好的耐低温析出性;DIDP作为主增塑剂时具有耐高温析出性;氯化石蜡可作为辅助增塑剂;以上增塑剂可根据各自特点复配使用.%The plasticizing mechanism of several plasticizers (DBP, DOP, DIDP, DOS, TOTM and chlorinated paraffin wax, etc,) to the chlorinated polyethylene (CPE) waterproofing materials was studied. Keeping other conditions under the same basis, the test selected the number of copies of plasticizer as 25. On this basis test compared the compatibility of these plasticizers and the CPE resin from mechanical properties, heat resistance, rheological properties and microstructure of the four aspects, inorder to compare the difference of plasticizing effect. DSC and SEM showed that the plastic effect of phthalic acid ester plasticizer was much better than other types of plasticizer, and the plastic effect of DOP was the best. When DOS was as the main plasticizer it can provide the material better low temperature resistance ability. If DIDP was as the main plasticizer it can provide the material better high temperature resistance ability. Chlorinated paraffin wax cannot be used as main plasticizer but as auxiliary plasticizer. These plasticizers can be used together according to their characteristics.

  4. Impact of global warming at the range margins: phenotypic plasticity and behavioral thermoregulation will buffer an endemic amphibian.

    Science.gov (United States)

    Ruiz-Aravena, Manuel; Gonzalez-Mendez, Avia; Estay, Sergio A; Gaitán-Espitia, Juan D; Barria-Oyarzo, Ismael; Bartheld, José L; Bacigalupe, Leonardo D

    2014-12-01

    When dispersal is not an option to evade warming temperatures, compensation through behavior, plasticity, or evolutionary adaptation is essential to prevent extinction. In this work, we evaluated whether there is physiological plasticity in the thermal performance curve (TPC) of maximum jumping speed in individuals acclimated to current and projected temperatures and whether there is an opportunity for behavioral thermoregulation in the desert landscape where inhabits the northernmost population of the endemic frog Pleurodema thaul. Our results indicate that individuals acclimated to 20°C and 25°C increased the breath of their TPCs by shifting their upper limits with respect to when they were acclimated at 10°C. In addition, even when dispersal is not possible for this population, the landscape is heterogeneous enough to offer opportunities for behavioral thermoregulation. In particular, under current climatic conditions, behavioral thermoregulation is not compulsory as available operative temperatures are encompassed within the population TPC limits. However, for severe projected temperatures under climate change, behavioral thermoregulation will be required in the sunny patches. In overall, our results suggest that this population of Pleurodema thaul will be able to endure the worst projected scenario of climate warming as it has not only the physiological capacities but also the environmental opportunities to regulate its body temperature behaviorally.

  5. Metaplasticity and Behavior: How Training and Inflammation Affect Plastic Potential within the Spinal Cord and Recovery after Injury

    Directory of Open Access Journals (Sweden)

    James W Grau

    2014-09-01

    Full Text Available Research has shown that spinal circuits have the capacity to adapt in response to training, nociceptive stimulation and peripheral inflammation. These changes in neural function are mediated by physiological and neurochemical systems analogous to those that support plasticity within the hippocampus (e.g., long-term potentiation and the NMDA receptor. As observed in the hippocampus, engaging spinal circuits can have a lasting impact on plastic potential, enabling or inhibiting the capacity to learn. These effects are related to the concept of metaplasticity. Behavioral paradigms are described that induce metaplastic effects within the spinal cord. Uncontrollable/unpredictable stimulation, and peripheral inflammation, induce a form of maladaptive plasticity that inhibits spinal learning. Conversely, exposure to controllable or predictable stimulation engages a form of adaptive plasticity that counters these maladaptive effects and enables learning. Adaptive plasticity is tied to an up-regulation of brain derived neurotrophic factor (BDNF. Maladaptive plasticity is linked to processes that involve kappa opioids, the metabotropic glutamate (mGlu receptor, glia, and the cytokine tumor necrosis factor (TNF. Uncontrollable nociceptive stimulation also impairs recovery after a spinal contusion injury and fosters the development of pain (allodynia. These adverse effects are related to an up-regulation of TNF and a down-regulation of BDNF and its receptor (TrkB. In the absence of injury, brain systems quell the sensitization of spinal circuits through descending serotonergic fibers and the serotonin 1A (5HT 1A receptor. This protective effect is blocked by surgical anesthesia. Disconnected from the brain, intracellular Cl- concentrations increase (due to a down-regulation of the cotransporter KCC2, which causes GABA to have an excitatory effect. It is suggested that BDNF has a restorative effect because it up-regulates KCC2 and re-establishes GABA

  6. TrkB/BDNF-dependent striatal plasticity and behavior in a genetic model of epilepsy: modulation by valproic acid.

    Science.gov (United States)

    Ghiglieri, Veronica; Sgobio, Carmelo; Patassini, Stefano; Bagetta, Vincenza; Fejtova, Anna; Giampà, Carmela; Marinucci, Silvia; Heyden, Alexandra; Gundelfinger, Eckart D; Fusco, Francesca R; Calabresi, Paolo; Picconi, Barbara

    2010-06-01

    In mice lacking the central domain of the presynaptic scaffold Bassoon the occurrence of repeated cortical seizures induces cell-type-specific plasticity changes resulting in a general enhancement of the feedforward inhibition within the striatal microcircuit. Early antiepileptic treatment with valproic acid (VPA) reduces epileptic attacks, inhibits the emergence of pathological form of plasticity in fast-spiking (FS) interneurons and restores physiological striatal synaptic plasticity in medium spiny (MS) neurons. Brain-derived neurotrophic factor (BDNF) is a key factor for the induction and maintenance of synaptic plasticity and it is also implicated in the mechanisms underlying epilepsy-induced adaptive changes. In this study, we explore the possibility that the TrkB/BDNF system is involved in the striatal modifications associated with the Bassoon gene (Bsn) mutation. In epileptic mice abnormal striatum-dependent learning was paralleled by higher TrkB levels and an altered distribution of BDNF. Accordingly, subchronic intrastriatal administration of k252a, an inhibitor of TrkB receptor tyrosine kinase activity, reversed behavioral alterations in Bsn mutant mice. In addition, in vitro manipulations of the TrkB/BDNF complex by k252a, prevented the emergence of pathological plasticity in FS interneurons. Chronic treatment with VPA, by reducing seizures, was able to rebalance TrkB to control levels favoring a physiological redistribution of BDNF between MS neurons and FS interneurons with a concomitant recovery of striatal plasticity. Our results provide the first indication that BDNF is involved in determining the striatal alterations occurring in the early-onset epileptic syndrome associated with the absence of presynaptic protein Bassoon.

  7. Metaplasticity and behavior: how training and inflammation affect plastic potential within the spinal cord and recovery after injury

    Science.gov (United States)

    Grau, James W.; Huie, J. Russell; Lee, Kuan H.; Hoy, Kevin C.; Huang, Yung-Jen; Turtle, Joel D.; Strain, Misty M.; Baumbauer, Kyle M.; Miranda, Rajesh M.; Hook, Michelle A.; Ferguson, Adam R.; Garraway, Sandra M.

    2014-01-01

    Research has shown that spinal circuits have the capacity to adapt in response to training, nociceptive stimulation and peripheral inflammation. These changes in neural function are mediated by physiological and neurochemical systems analogous to those that support plasticity within the hippocampus (e.g., long-term potentiation and the NMDA receptor). As observed in the hippocampus, engaging spinal circuits can have a lasting impact on plastic potential, enabling or inhibiting the capacity to learn. These effects are related to the concept of metaplasticity. Behavioral paradigms are described that induce metaplastic effects within the spinal cord. Uncontrollable/unpredictable stimulation, and peripheral inflammation, induce a form of maladaptive plasticity that inhibits spinal learning. Conversely, exposure to controllable or predictable stimulation engages a form of adaptive plasticity that counters these maladaptive effects and enables learning. Adaptive plasticity is tied to an up-regulation of brain derived neurotrophic factor (BDNF). Maladaptive plasticity is linked to processes that involve kappa opioids, the metabotropic glutamate (mGlu) receptor, glia, and the cytokine tumor necrosis factor (TNF). Uncontrollable nociceptive stimulation also impairs recovery after a spinal contusion injury and fosters the development of pain (allodynia). These adverse effects are related to an up-regulation of TNF and a down-regulation of BDNF and its receptor (TrkB). In the absence of injury, brain systems quell the sensitization of spinal circuits through descending serotonergic fibers and the serotonin 1A (5HT 1A) receptor. This protective effect is blocked by surgical anesthesia. Disconnected from the brain, intracellular Cl- concentrations increase (due to a down-regulation of the cotransporter KCC2), which causes GABA to have an excitatory effect. It is suggested that BDNF has a restorative effect because it up-regulates KCC2 and re-establishes GABA-mediated inhibition

  8. Environmental risk and influence of chemicals from plastic materials on children’s health – the challenge also for paediatricians

    Directory of Open Access Journals (Sweden)

    Zbigniew Rudkowski

    2013-03-01

    Full Text Available Chemicals artificially synthesized and leaching into a common environment are a toxicological risk particularly in prenatal period and in early childhood. The risk exists due to the contact with xenogenic substances from maternal breast milk and other food, polluted air and water, plastic materials, cosmetics. All endocrine and neurological disruptors (EDC pass across placenta, then can cause hormonal, neurological or metabolic disorders mainly due to estrogenic action. Bisphenol A is one of endocrine disruptors leaching from polychlorobiphenyl plastic (PCB, present commonly in baby polycarbonate bottles. Phtalates like DEHP, DOP, DINP, DIDP, DIPB, DBP or BBP are used as plasticizers making plastics softer and more flexible. Flame retardants f, ex, PBDE (polybrominated diphenyleter are added to polyurethane foams, and HBCD (hexabromocyclododecane is a compound of polystyrene electric insulation. Perfluorinated compounds (PFC are some hundreds substancies and mostly used is PFOS (Perfluoroacetate sulphonate and PFOA (perfluoroacetic acid repelling water, grease and dirt; they are used as impregnating and cleaning agents, and PTFE (polytetrafluoroethylen known as Teflon or Goretex. The toxicity of xenogens for experimental animals is confirmed., but a harmful effect on humans is still discussed what is based only on epidemiological but not experimental studies. Epidemiological studies link human EDC exposure with hormonal, neurological and behavioural distorders f.ex. early maturation of girls, obesity, metabolic syndrome, and type 2 diabetes, and likely weakening of postvaccinal immunity. The awareness on environmental risks is essential for rationale behaviour diminishing the exposition and also being an important element of contemporary health promotion

  9. [The emergency plastic reconstruction of the tympanic membrane defects of post-traumatic and iatrogenic etiology with the application of the nanostructured bioplastic material].

    Science.gov (United States)

    Zabirov, R A; Kar'kaeva, S M; Shchetinin, V N; Akimov, A V

    2014-01-01

    The objective of the present study was to estimate the effectiveness of the application of the nanostructured bioplastic material for the plastic reconstruction of tympanic defects of post-traumatic and iatrogenic etiology. The authors report the results of the emergency plastic reconstruction of tympanic defects of post-traumatic and iatrogenic nature with the application of the nanostructured bioplastic material (giamatrix). The analysis of the results of the study prfovidd definitive evidence of the effectiveness of plastic reconstruction of tympanic defects with the application of the nanostructured bioplastic material.

  10. Tribological Behavior of Journal Bearing Material under Different Lubricants

    Directory of Open Access Journals (Sweden)

    S. Baskar

    2014-06-01

    Full Text Available The friction and wear behavior of journal bearing material has been investigated using pin on disc wear tester with three different lubricating oils i.e. synthetic lubricating oil (SAE20W40, chemically modified rapeseed oil (CMRO, chemically modified rapeseed oil with Nano CuO. Wear tests were carried out at maximum load of 200 N and sliding speeds of 2 – 10 m/s. The results showed that the friction and wear behavior of the journal bearing material have changed according to the sliding conditions and lubricating oils. The journal bearing material has a lower friction coefficient for CMRO with Nano CuO than other two oils. Higher wear of journal bearing material was observed in SAE 20W40 and CMRO. Worn surfaces of the journal bearing material with three lubricating oils were examined using scanning electron microscope (SEM and wear mechanisms were discussed.

  11. Determination of the strain rate dependent thermal softening behavior of thermoplastic materials for crash simulations

    Science.gov (United States)

    Hopmann, Christian; Klein, Jan; Schöngart, Maximilian

    2016-03-01

    Thermoplastic materials are increasingly used as a light weight replacement for metal, especially in automotive applications. Typical examples are frontends and bumpers. The loads on these structures are very often impulsive, for example in a crash situation. A high rate of loading causes a high strain rate in the material which has a major impact on the mechanical behavior of thermoplastic materials. The stiffness as well as the rigidity of polymers increases to higher strain rates. The increase of the mechanical properties is superimposed at higher rates of loading by another effect which works reducing on stiffness and rigidity, the increase of temperature caused by plastic deformation. The mechanical behavior of thermoplastic materials is influenced by temperature opposing to strain rate. The stiffness and rigidity are decreased to higher values of temperature. The effect of thermal softening on thermoplastic materials is investigated at IKV. For this purpose high-speed tensile tests are performed on a blend, consisting of Polybutylenterephthalate (PBT) and Polycarbonate (PC). In preliminary investigations the effects of strain rate on the thermomechanical behavior of thermoplastic materials was studied by different authors. Tensile impact as well as split Hopkinson pressure bar (SHPB) tests were conducted in combination with high-speed temperature measurement, though, the authors struggled especially with temperature measurement. This paper presents an approach which uses high-speed strain measurement to transpire the link between strain, strain rate and thermal softening as well as the interdependency between strain hardening and thermal softening. The results show a superimposition of strain hardening and thermal softening, which is consistent to preliminary investigations. The advantage of the presented research is that the results can be used to calibrate damage and material models to perform mechanical simulations using Finite Element Analysis.

  12. Adaptive behavior of neighboring neurons during adaptation-induced plasticity of orientation tuning in V1

    Directory of Open Access Journals (Sweden)

    Shumikhina Svetlana

    2009-12-01

    Full Text Available Abstract Background Sensory neurons display transient changes of their response properties following prolonged exposure to an appropriate stimulus (adaptation. In adult cat primary visual cortex, orientation-selective neurons shift their preferred orientation after being adapted to a non-preferred orientation. The direction of those shifts, towards (attractive or away (repulsive from the adapter depends mostly on adaptation duration. How the adaptive behavior of a neuron is related to that of its neighbors remains unclear. Results Here we show that in most cases (75%, cells shift their preferred orientation in the same direction as their neighbors. We also found that cells shifting preferred orientation differently from their neighbors (25% display three interesting properties: (i larger variance of absolute shift amplitude, (ii wider tuning bandwidth and (iii larger range of preferred orientations among the cluster of cells. Several response properties of V1 neurons depend on their location within the cortical orientation map. Our results suggest that recording sites with both attractive and repulsive shifts following adaptation may be located in close proximity to iso-orientation domain boundaries or pinwheel centers. Indeed, those regions have a more diverse orientation distribution of local inputs that could account for the three properties above. On the other hand, sites with all cells shifting their preferred orientation in the same direction could be located within iso-orientation domains. Conclusions Our results suggest that the direction and amplitude of orientation preference shifts in V1 depend on location within the orientation map. This anisotropy of adaptation-induced plasticity, comparable to that of the visual cortex itself, could have important implications for our understanding of visual adaptation at the psychophysical level.

  13. Microstructural evolution and deformation behavior of twinning-induced plasticity (TWIP) steel during wire drawing

    Energy Technology Data Exchange (ETDEWEB)

    Hwang, Joong-Ki [Graduate Institute of Ferrous Technology, POSTECH, Pohang 790-784 (Korea, Republic of); Steel Products Research Group, Technical Research Laboratories, POSCO, Pohang 790-785 (Korea, Republic of); Yi, Il-Cheol [Graduate Institute of Ferrous Technology, POSTECH, Pohang 790-784 (Korea, Republic of); Son, Il-Heon; Yoo, Jang-Yong [Steel Products Research Group, Technical Research Laboratories, POSCO, Pohang 790-785 (Korea, Republic of); Kim, Byoungkoo [Materials Technology Development Team, DHIC, Changwon 642-792 (Korea, Republic of); Zargaran, A. [Graduate Institute of Ferrous Technology, POSTECH, Pohang 790-784 (Korea, Republic of); Kim, Nack J., E-mail: njkim@postech.ac.kr [Graduate Institute of Ferrous Technology, POSTECH, Pohang 790-784 (Korea, Republic of)

    2015-09-17

    The effect of wire drawing on the microstructural evolution and deformation behavior of Fe–Mn–Al–C twinning-induced plasticity (TWIP) steel has been investigated. The inhomogeneities of the stress state, texture, microstructure, and mechanical properties were clarified over the cross section of drawn wire with the aid of numerical simulation, Schmid factor analysis, and electron backscatter diffraction (EBSD) techniques. The analysis of texture in drawn wire shows that a mixture of <111> and <100> fiber texture was developed with strain; however, the distribution of <111> and <100> fibers was inhomogeneous along the radial direction of wire due to uneven strain distribution and different stress state along the radial direction. It has also been shown that the morphology, volume fraction, and variant system of twins as well as twinning rate were dependent on the imposed stress state. The surface area was subjected to larger strain and more complex stress state involving compression, shear, and tension than the center area, resulting in a larger twin volume fraction and more twin variants in the former than in the latter at all the strain levels. While the surface area was saturated with twins at an early stage of drawing, the center area was not saturated with twins even at fracture, implying that the fracture of wire were initiated at the surface area because of the exhaustion of ductility due to twinning. Based on these results, it is suggested that imposing a uniform strain distribution along the radial direction of wire by the control of processing conditions such as die angle and amount of reduction per pass is necessary to increase the drawing limit of TWIP steel.

  14. Mechanical Properties and Fracture Behavior of Cu-Co-Be Alloy after Plastic Deformation and Heat Treatment

    Institute of Scientific and Technical Information of China (English)

    Yan-jun ZHOU; Ke-xing SONG; Jian-dong XING; Zhou LI; Xiu-hua GUO

    2016-01-01

    Mechanical properties and fracture behavior of Cu-0.84Co-0.23Be alloy after plastic deformation and heat treatment were comparatively investigated.Severe plastic deformation by hot extrusion and cold drawing was adopted to induce large plastic strain of Cu-0.84Co-0.23Be alloy.The tensile strength and elongation are up to 476.6 MPa and 1 8%,respectively.The fractured surface consists of deep dimples and micro-voids.Due to the formation of su-persaturated solid solution on the Cu matrix by solution treatment at 950 ℃ for 1 h,the tensile strength decreased to 271.9 MPa,while the elongation increased to 42%.The fracture morphology is parabolic dimple.Furthermore,the tensile strength increased significantly to 580.2 MPa after aging at 480 ℃ for 4 h.During the aging process,a large number of precipitates formed and distributed on the Cu matrix.The fracture feature of aged specimens with low elongation (4.6%)exhibits an obvious brittle intergranular fracture.It is confirmed that the mechanical properties and fracture behavior are dominated by the microstructure characteristics of Cu-0.84Co-0.23Be alloy after plastic de-formation and heat treatment.In addition,the fracture behavior at 450 ℃ of aged Cu-0.84Co-0.23Be alloy was also studied.The tensile strength and elongation are 383.6 MPa and 11.2%,respectively.The fractured morphologies are mainly candy-shaped with partial parabolic dimples and equiaxed dimples.The fracture mode is multi-mixed mechanism that brittle intergranular fracture plays a dominant role and ductile fracture is secondary.

  15. A Visco-plastic Model of Magnetorheological Materials%磁流变材料的粘塑性模型

    Institute of Scientific and Technical Information of China (English)

    司鹄; 彭向和

    2001-01-01

    Magnetorheological materials are a class of smart materials whose reological properties may be rapidly varied by application of magnetic field. By a simple mechanical mold, a visco-plastic model for the materials is developed. It is shown that the model can describe the variation of the mechanical properties for the Magnetorheological materials in the different magnetic field. The result is shown that the model can characterize the mechanical properties of Magnetorheological Materials in plastic and viscous variation.%在外加磁场作用下,磁流变材料的力学性质可迅速发生变化甚至发生相变固化,材料的性能依赖于外加磁场的强度。作者基于一个简单的机械模型,发展了磁流变体的粘塑性本构描述,预言了磁流变流体的力学行为随磁场强度的变化,较好地描述材料在不同磁场强度下应力随应变而变化。结果表明所提出的模型能描述MR材料的塑性变形、粘性变形等内在的力学响应特性。

  16. Dynamic behavior of oscillatory plastic flow in a smectic liquid crystal

    Science.gov (United States)

    Herke, Richard A.; Clark, 1., Noel A.; Handschy, Mark A.

    1997-09-01

    Dynamic surface force measurements are used to study the response of a smectic-A liquid crystal under layer-normal stress. The smectic A is confined in a spherical wedge between crossed cylindrical surfaces having a minimum gap spacing of 0.5-4 μm. The force transmitted between the surfaces by the liquid crystal is measured vs surface spacing using a capacitance micrometer-based surface force apparatus. Above a threshold stress plastic flow results, consisting of individual layers being excluded or included. Each layer flow event has an intriguing dynamical structure, beginning with an enhanced drift rate, which can last for many minutes, accelerating to a rapid separation change of ~1 or 2 s duration wherein the bulk of the relaxation occurs, and tapering off to a background drift rate over a period of a 100 s or more. The single-layer nature of the observed jumps in liquid crystal thickness indicates that they are topological in origin, i.e., slippage events in the phase of the smectic-A order parameter that must necessarily involve edge or screw dislocations. A model based on the Glaberson-Clem-Oswald-Kléman helical instability in screw dislocations is the only one found to explain the data, the layering events arising from a cascade of these helical instabilities sweeping radially outward through the smectic-A sample. The slow precursor acceleration is due to the nucleation of a few helices in the thin central portion of the sample. As time goes on, the force relieved is transferred to the rest of the sample, pushing larger and larger amounts of the area into the unstable regime, and a type of chain reaction occurs whereby the bulk of a layer is removed. In the end only the material at the edge of the droplet, where the thickness is largest, is left to slowly continue to nucleate, producing a long-term tail.

  17. Spinal Plasticity and Behavior: BDNF-Induced Neuromodulation in Uninjured and Injured Spinal Cord

    Directory of Open Access Journals (Sweden)

    Sandra M. Garraway

    2016-01-01

    Full Text Available Brain-derived neurotrophic factor (BDNF is a member of the neurotrophic factor family of signaling molecules. Since its discovery over three decades ago, BDNF has been identified as an important regulator of neuronal development, synaptic transmission, and cellular and synaptic plasticity and has been shown to function in the formation and maintenance of certain forms of memory. Neural plasticity that underlies learning and memory in the hippocampus shares distinct characteristics with spinal cord nociceptive plasticity. Research examining the role BDNF plays in spinal nociception and pain overwhelmingly suggests that BDNF promotes pronociceptive effects. BDNF induces synaptic facilitation and engages central sensitization-like mechanisms. Also, peripheral injury-induced neuropathic pain is often accompanied with increased spinal expression of BDNF. Research has extended to examine how spinal cord injury (SCI influences BDNF plasticity and the effects BDNF has on sensory and motor functions after SCI. Functional recovery and adaptive plasticity after SCI are typically associated with upregulation of BDNF. Although neuropathic pain is a common consequence of SCI, the relation between BDNF and pain after SCI remains elusive. This article reviews recent literature and discusses the diverse actions of BDNF. We also highlight similarities and differences in BDNF-induced nociceptive plasticity in naïve and SCI conditions.

  18. Recent advances in high performance poly(lactide): From ``green'' plasticization to super-tough materials via (reactive) compounding

    Science.gov (United States)

    Kfoury, Georgio; Raquez, Jean-Marie; Hassouna, Fatima; Odent, Jérémy; Toniazzo, Valérie; Ruch, David; Dubois, Philippe

    2013-12-01

    Due to its origin from renewable resources, its biodegradability, and recently, its industrial implementation at low costs, poly(lactide) (PLA) is considered as one of the most promising ecological, bio-sourced and biodegradable plastic materials to potentially and increasingly replace traditional petroleum derived polymers in many commodity and engineering applications. Beside its relatively high rigidity (high tensile strength and modulus compared with many common thermoplastics such as poly(ethylene terephthalate) (PET), high impact poly(styrene) (HIPS) and poly(propylene) (PP)), PLA suffers from an inherent brittleness, which can limit its applications especially where mechanical toughness such as plastic deformation at high impact rates or elongation is required. Therefore, the curve plotting stiffness vs. impact resistance and ductility must be shifted to higher values for PLA-based materials, while being preferably fully bio-based and biodegradable upon the application. This review aims to establish a state of the art focused on the recent progresses and preferably economically viable strategies developed in the literature for significantly improve the mechanical performances of PLA. A particular attention is given to plasticization as well as to impact resistance modification of PLA in the case of (reactive) blending PLA-based systems.

  19. Recent advances in high performance poly(lactide): from "green" plasticization to super-tough materials via (reactive) compounding.

    Science.gov (United States)

    Kfoury, Georgio; Raquez, Jean-Marie; Hassouna, Fatima; Odent, Jérémy; Toniazzo, Valérie; Ruch, David; Dubois, Philippe

    2013-01-01

    Due to its origin from renewable resources, its biodegradability, and recently, its industrial implementation at low costs, poly(lactide) (PLA) is considered as one of the most promising ecological, bio-sourced and biodegradable plastic materials to potentially and increasingly replace traditional petroleum derived polymers in many commodity and engineering applications. Beside its relatively high rigidity [high tensile strength and modulus compared with many common thermoplastics such as poly(ethylene terephthalate) (PET), high impact poly(styrene) (HIPS) and poly(propylene) (PP)], PLA suffers from an inherent brittleness, which can limit its applications especially where mechanical toughness such as plastic deformation at high impact rates or elongation is required. Therefore, the curve plotting stiffness vs. impact resistance and ductility must be shifted to higher values for PLA-based materials, while being preferably fully bio-based and biodegradable upon the application. This review aims to establish a state of the art focused on the recent progresses and preferably economically viable strategies developed in the literature for significantly improve the mechanical performances of PLA. A particular attention is given to plasticization as well as to impact resistance modification of PLA in the case of (reactive) blending PLA-based systems.

  20. Recent advances in high performance poly(lactide: From green plasticization to super-tough materials via (reactive compounding

    Directory of Open Access Journals (Sweden)

    Georgio eKfoury

    2013-12-01

    Full Text Available Due to its origin from renewable resources, its biodegradability, and recently, its industrial implementation at low costs, poly(lactide (PLA is considered as one of the most promising ecological, bio-sourced and biodegradable plastic materials to potentially and increasingly replace traditional petroleum derived polymers in many commodity and engineering applications. Beside its relatively high rigidity (high tensile strength and modulus compared with many common thermoplastics such as poly(ethylene terephthalate (PET, high impact poly(styrene (HIPS and poly(propylene (PP, PLA suffers from an inherent brittleness, which can limit its applications especially where mechanical toughness such as plastic deformation at high impact rates or elongation is required. Therefore, the curve plotting stiffness vs. impact resistance and ductility must be shifted to higher values for PLA-based materials, while being preferably fully bio-based and biodegradable upon the application.This review aims to establish a state of the art focused on the recent progresses and preferably economically viable strategies developed in the literature for significantly improve the mechanical performances of PLA. A particular attention is given to plasticization as well as to impact resistance modification of PLA in the case of (reactive blending PLA-based systems.

  1. Tribological Behavior of Journal Bearing Material under Different Lubricants

    OpenAIRE

    2014-01-01

    The friction and wear behavior of journal bearing material has been investigated using pin on disc wear tester with three different lubricating oils i.e. synthetic lubricating oil (SAE20W40), chemically modified rapeseed oil (CMRO), chemically modified rapeseed oil with Nano CuO. Wear tests were carried out at maximum load of 200 N and sliding speeds of 2 – 10 m/s. The results showed that the friction and wear behavior of the journal bearing material have changed according to the sliding cond...

  2. Sustainable Materials Management (SMM) Web Academy Webinar: Let’s WRAP (Wrap Recycling Action Program): Best Practices to Boost Plastic Film Recycling in Your Community

    Science.gov (United States)

    This is a webinar page for the Sustainable Management of Materials (SMM) Web Academy webinar titled Let’s WRAP (Wrap Recycling Action Program): Best Practices to Boost Plastic Film Recycling in Your Community

  3. Mechanisms of Plastic and Fracture Instabilities for Alloy Development of Fusion Materials. Final Project Report for period July 15, 1998 - July 14, 2003

    Energy Technology Data Exchange (ETDEWEB)

    Ghoniem, N. M.

    2003-07-14

    The main objective of this research was to develop new computational tools for the simulation and analysis of plasticity and fracture mechanisms of fusion materials, and to assist in planning and assessment of corresponding radiation experiments.

  4. Quality and safety aspects of reusable plastic food packaging materials : influence of reuse on intrinsic properties

    NARCIS (Netherlands)

    Jetten, J.; Kruijf, N. de

    2002-01-01

    The aim of the project was to develop a comprehensive package of quality assurance criteria for use by the industry and by regulatory authorities to ensure the quality and safety-in-use (sensory, microbiological and chemical safety) of reused plastics for food packaging. The paper describes the

  5. Effect of Plastic Spin on Localization Predictions for a Porous Ductile Material

    NARCIS (Netherlands)

    Tvergaard, Viggo; Giessen, Erik van der

    1991-01-01

    Various constitutive frameworks for macroscopic large strain elastoplasticity have recently identified the plastic spin as one of the key concepts in the description of anisotropic hardening. These theories involve a particular corotational stress rate that differs from the Jaumann stress rate by te

  6. Quality and safety aspects of reusable plastic food packaging materials : influence of reuse on intrinsic properties

    NARCIS (Netherlands)

    Jetten, J.; Kruijf, N. de

    2002-01-01

    The aim of the project was to develop a comprehensive package of quality assurance criteria for use by the industry and by regulatory authorities to ensure the quality and safety-in-use (sensory, microbiological and chemical safety) of reused plastics for food packaging. The paper describes the inve

  7. Literature review of the lifetime of DOE materials: Aging of plastic bonded explosives and the explosives and polymers contained therein

    Energy Technology Data Exchange (ETDEWEB)

    Burgess, C.E.; Woodyard, J.D. [West Texas A and M Univ., Canyon, TX (United States); Rainwater, K.A. [Texas Tech Univ., Lubbock, TX (United States); Lightfoot, J.M. [Pantex Plant, Amarillo, TX (United States); Richardson, B.R. [Engineered Carbons, Inc., Borger, TX (United States)

    1998-09-01

    There are concerns about the lifetime of the nation`s stockpile of high explosives (HEs) and their components. The DOE`s Core Surveillance and Enhanced Surveillance programs specifically target degradation of HE, binders, and plastic-bonded explosives (PBXs) for determination of component lifetimes and handling procedures. The principal goal of this project is to identify the decomposition mechanisms of HEs, plasticizers, and plastic polymer binders resulting from exposure to ionizing radiation, heat, and humidity. The primary HEs of concern are 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) and 1,3,5,7-tetranitro-1,3,5,7-tetraazocyclooctane (HMX). Hexahydro-1,3,5-triazine (RDX) is closely related to these two compounds and is also included in the literature review. Both Kel-F 800 and Estane are polymers of interest. A stabilizer, Irganox 1010, and an energetic plasticizer that is a blend of acetaldehyde 2,2-dinitropropyl acetal, are also of interest, but the focus of this report will be on the explosives and polymers. This presents a literature review that provides background on the synthesis, degradation, and techniques to analyze TATB, HMX, RDX, Kel-F 800, Estane, and the PBXs of these compounds. As there are many factors that can influence degradation of materials, the degradation discussion will be divided into sections based on each factor and how it might affect the degradation mechanism. The factors reviewed that influence the degradation of these materials are exposure to heat, UV- and {gamma}-irradiation, and the chemistry of these compounds. The report presents a recently compiled accounting of the available literature. 80 refs., 7 figs.

  8. Plastic Bridge

    Institute of Scientific and Technical Information of China (English)

    履之

    1994-01-01

    Already ubiquitous in homes and cars, plastic is now appearing inbridges. An academic-industrial consortium based at the University ofCalifornia in San Diego is launching a three-year research program aimed atdeveloping the world’s first plastic highway bridge, a 450-foot span madeentirely from glass-,carbon,and polymer-fiber-reinforced composite mate-rials, the stuff of military aircraft. It will cross Interstate 5 to connect thetwo sides of the school’s campus.

  9. Inactivation of BRD7 results in impaired cognitive behavior and reduced synaptic plasticity of the medial prefrontal cortex.

    Science.gov (United States)

    Xu, Yang; Cao, Wenyu; Zhou, Ming; Li, Changqi; Luo, Yanwei; Wang, Heran; Zhao, Ran; Jiang, Shihe; Yang, Jing; Liu, Yukun; Wang, Xinye; Li, Xiayu; Xiong, Wei; Ma, Jian; Peng, Shuping; Zeng, Zhaoyang; Li, Xiaoling; Tan, Ming; Li, Guiyuan

    2015-06-01

    BRD7 is a bromodomain-containing protein (BCP), and recent evidence implicates the role of BCPs in the initiation and development of neurodevelopmental disorders. However, few studies have investigated the biological functions of BRD7 in the central nervous system. In our study, BRD7 was found to be widely expressed in various regions of the mouse brain, including the medial prefrontal cortex (mPFC), caudate putamen (CPu), hippocampus (Hip), midbrain (Mb), cerebellum (Cb), and mainly co-localized with neuron but not with glia. Using a BRD7 knockout mouse model and a battery of behavioral tests, we report that disruption of BRD7 results in impaired cognitive behavior leaving the emotional behavior unaffected. Moreover, a series of proteins involved in synaptic plasticity were decreased in the medial prefrontal cortex and there was a concomitant decrease in neuronal spine density and dendritic branching in the medial prefrontal cortex. However, no significant difference was found in the hippocampus compared to the wild-type mice. Thus, BRD7 might play a critical role in the regulation of synaptic plasticity and affect cognitive behavior.

  10. Estimation of ductile fracture behavior incorporating material anisotropy

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Shin Beom; Lee, Dock Jin; Jeong, Jae Uk [Sungkyunkwan University, Seoul (Korea, Republic of); Chang, Yoon Suk [Dept. of Nuclear Engineering, Kyung Hee University, Seoul (Korea, Republic of); Kim, Min Chul; Lee, Bong Sang [Nuclear Material Technology Division, Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2012-10-15

    Since standardized fracture test specimens cannot be easily extracted from in-service components, several alternative fracture toughness test methods have been proposed to characterize the deformation and fracture resistance of materials. One of the more promising alternatives is the local approach employing the SP(Small Punch) testing technique. However, this process has several limitations such as a lack of anisotropic yield potential and tediousness in the damage parameter calibration process. The present paper investigates estimation of ductile fracture resistance(J-R) curve by FE(Finite Element) analyses using an anisotropic damage model and enhanced calibration procedure. In this context, specific tensile tests to quantify plastic strain ratios were carried out and SP test data were obtained from the previous research. Also, damage parameters constituting the Gurson-Tvergaard-Needleman model in conjunction with Hill;s 48 yield criterion were calibrated for a typical nuclear reactor material through a genetic algorithm. Finally, the J-R curve of a standard compact tension specimen was predicted by further detailed FE analyses employing the calibrated damage parameters. It showed a lower fracture resistance of the specimen material than that based on the isotropic yield criterion. Therefore, a more realistic J-R curve of a reactor material can be obtained effectively from the proposed methodology by taking into account a reduced load-carrying capacity due to anisotropy.

  11. Biopolymer foams - Relationship between material characteristics and foaming behavior of cellulose based foams

    Science.gov (United States)

    Rapp, F.; Schneider, A.; Elsner, P.

    2014-05-01

    Biopolymers are becoming increasingly important to both industry and consumers. With regard to waste management, CO2 balance and the conservation of petrochemical resources, increasing efforts are being made to replace standard plastics with bio-based polymers. Nowadays biopolymers can be built for example of cellulose, lactic acid, starch, lignin or bio mass. The paper will present material properties of selected cellulose based polymers (cellulose propionate [CP], cellulose acetate butyrate [CAB]) and corresponding processing conditions for particle foams as well as characterization of produced parts. Special focus is given to the raw material properties by analyzing thermal behavior (differential scanning calorimetry), melt strength (Rheotens test) and molecular weight distribution (gel-permeation chromatography). These results will be correlated with the foaming behavior in a continuous extrusion process with physical blowing agents and underwater pelletizer. Process set-up regarding particle foam technology, including extrusion foaming and pre-foaming, will be shown. The characteristics of the resulting foam beads will be analyzed regarding part density, cell morphology and geometry. The molded parts will be tested on thermal conductivity as well as compression behavior (E-modulus, compression strength).

  12. Biopolymer foams - Relationship between material characteristics and foaming behavior of cellulose based foams

    Energy Technology Data Exchange (ETDEWEB)

    Rapp, F., E-mail: florian.rapp@ict.fraunhofer.de, E-mail: anja.schneider@ict.fraunhofer.de; Schneider, A., E-mail: florian.rapp@ict.fraunhofer.de, E-mail: anja.schneider@ict.fraunhofer.de [Fraunhofer Institute for Chemical Technology ICT (Germany); Elsner, P., E-mail: peter.elsner@ict.fraunhofer.de [Fraunhofer Institute for Chemical Technology ICT, Germany and Karlsruhe Institute of Technology KIT (Germany)

    2014-05-15

    Biopolymers are becoming increasingly important to both industry and consumers. With regard to waste management, CO{sub 2} balance and the conservation of petrochemical resources, increasing efforts are being made to replace standard plastics with bio-based polymers. Nowadays biopolymers can be built for example of cellulose, lactic acid, starch, lignin or bio mass. The paper will present material properties of selected cellulose based polymers (cellulose propionate [CP], cellulose acetate butyrate [CAB]) and corresponding processing conditions for particle foams as well as characterization of produced parts. Special focus is given to the raw material properties by analyzing thermal behavior (differential scanning calorimetry), melt strength (Rheotens test) and molecular weight distribution (gel-permeation chromatography). These results will be correlated with the foaming behavior in a continuous extrusion process with physical blowing agents and underwater pelletizer. Process set-up regarding particle foam technology, including extrusion foaming and pre-foaming, will be shown. The characteristics of the resulting foam beads will be analyzed regarding part density, cell morphology and geometry. The molded parts will be tested on thermal conductivity as well as compression behavior (E-modulus, compression strength)

  13. Surveying FIFA Instructors' Behavioral Intention toward the Multimedia Teaching Materials

    Science.gov (United States)

    Armenteros, M.; Liaw, Shu-Sheng; Fernandez, M.; Diaz, R. Flores; Sanchez, R. Arteaga

    2013-01-01

    Instruction delivered via multimedia applications is changing the way elite football refereeing instructors teach the Laws of the Game. Although e-learning applications are popular, there is minimal research on instructors' attitudes toward these teaching materials. The purpose of this research is to explore instructors' behavioral intentions…

  14. Surveying FIFA Instructors' Behavioral Intention toward the Multimedia Teaching Materials

    Science.gov (United States)

    Armenteros, M.; Liaw, Shu-Sheng; Fernandez, M.; Diaz, R. Flores; Sanchez, R. Arteaga

    2013-01-01

    Instruction delivered via multimedia applications is changing the way elite football refereeing instructors teach the Laws of the Game. Although e-learning applications are popular, there is minimal research on instructors' attitudes toward these teaching materials. The purpose of this research is to explore instructors' behavioral intentions…

  15. Fundamental Understanding of Ambient and High-Temperature Plasticity Phenomena in Structural Materials in Advanced Reactors

    Energy Technology Data Exchange (ETDEWEB)

    Deo, Chaitanya; Zhu, Ting; McDowell, David

    2013-11-17

    The goal of this research project is to develop the methods and tools necessary to link unit processes analyzed using atomistic simulations involving interaction of vacancies and interstitials with dislocations, as well as dislocation mediation at sessile junctions and interfaces as affected by radiation, with cooperative influence on higher-length scale behavior of polycrystals. These tools and methods are necessary to design and enhance radiation-induced damage-tolerant alloys. The project will achieve this goal by applying atomistic simulations to characterize unit processes of: 1. Dislocation nucleation, absorption, and desorption at interfaces 2. Vacancy production, radiation-induced segregation of substitutional Cr at defect clusters (point defect sinks) in BCC Fe-Cr ferritic/martensitic steels 3. Investigation of interaction of interstitials and vacancies with impurities (V, Nb, Ta, Mo, W, Al, Si, P, S) 4. Time evolution of swelling (cluster growth) phenomena of irradiated materials 5. Energetics and kinetics of dislocation bypass of defects formed by interstitial clustering and formation of prismatic loops, informing statistical models of continuum character with regard to processes of dislocation glide, vacancy agglomeration and swelling, climb and cross slip This project will consider the Fe, Fe-C, and Fe-Cr ferritic/martensitic material system, accounting for magnetism by choosing appropriate interatomic potentials and validating with first principles calculations. For these alloys, the rate of swelling and creep enhancement is considerably lower than that of face-centered cubic (FCC) alloys and of austenitic Fe-Cr-Mo alloys. The team will confirm mechanisms, validate simulations at various time and length scales, and improve the veracity of computational models. The proposed research?s feasibility is supported by recent modeling of radiation effects in metals and alloys, interfacial dislocation transfer reactions in nano-twinned copper, and dislocation

  16. Study of Reactive Melt Processing Behavior of Externally Plasticized Cellulose Acetate in Presence of Isocyanate

    Directory of Open Access Journals (Sweden)

    Rafael Erdmann

    2014-12-01

    Full Text Available Two types of externally plasticized cellulose acetate (CA were chemically modified using 4,4'-methylene diphenyl diisocyanate (MDI as crosslinking agent. Crosslinking was performed in the molten state by means of melt mixing in an internal mixer. The viscoelastic properties of the non-crosslinked, externally plasticized CA show typical temperature dependence, similar to conventional thermoplastics. A strong increase in storage modulus is observed with increasing crosslink density indicating that the crosslinked compounds exhibit predominately elastic response. The complex viscosity also increases considerably with increasing crosslink density and does not reach the typical Newtonian plateau at low radial frequencies any more. The viscoelastic properties correlate well with the data recorded online during reactive melt processing in the internal mixer. In comparison to the non-crosslinked CA, the crosslinked compounds show higher glass transition temperature, higher VICAT softening temperatures, improved thermal stability and lower plasticizer evaporation at evaluated temperatures.

  17. Elasto-Plastic Constitutive Behavior in Three Lithofacies of the Cambrian Mt. Simon Sandstone, Illinois Basin, USA

    Science.gov (United States)

    Dewers, T.; Newell, P.; Broome, S. T.; Heath, J. E.; Bauer, S. J.

    2012-12-01

    The Mt. Simon Formation, a basal Cambrian sandstone underlying the Illinois Basin in the Central US, is a target for underground storage and waste injection which require an assessment of geomechanical behavior. The range of depositional environments, from braided streams and minor eolean features in the lower Mt Simon, to tidally-influenced near- and on-shore sands in the upper Mt. Simon, yield a heterogeneous formation with a range in porosity, permeability, and mechanical properties. We examine the experimental deformational behavior of three distinct Mt. Simon lithofacies via axisymmetric compressional testing. Initial yielding is confirmed with acoustic emissions in many of the tests and failure envelopes are determined for each lithofacies. The evolution of (assumed) isotropic elastic moduli are examined during testing by use of unload-reload cycles, which permit the separation of total measured strains into elastic and plastic (permanent) strains. The upper Mt Simon samples deform largely elastically at stresses encountered in the Illinois Basin, with very little modulus degradation. The lower Mt. Simon facies are weaker and deform plastically, with varying amounts of modulus degradation. Results are interpreted via petrographic observation of textural contrasts. This range in constitutive response is captured up to failure with a phenomenological elasto-plasticity model. Essential aspects to describe observed behavior used in the model include non-associative plasticity, stress-invariant dependent failure, an elliptical cap surface capturing shear effects on pore collapse, kinematic and isotropic hardening, nonlinear elasticity and elastic-plastic coupling, among other features. Static moduli derived from laboratory tests are compared to dynamic moduli from wellbore log response which can allow experimental results and model to be extrapolated to Mt. Simon occurrences across the basin. This work was funded in part by the Center for Frontiers of Subsurface

  18. Dependence of triboelectric charging behavior on material microstructure

    Science.gov (United States)

    Wang, Andrew E.; Gil, Phwey S.; Holonga, Moses; Yavuz, Zelal; Baytekin, H. Tarik; Sankaran, R. Mohan; Lacks, Daniel J.

    2017-08-01

    We demonstrate that differences in the microstructure of chemically identical materials can lead to distinct triboelectric charging behavior. Contact charging experiments are carried out between strained and unstrained polytetrafluoroethylene samples. Whereas charge transfer is random between samples of identical strain, when one of the samples is strained, systematic charge transfer occurs. No significant changes in the molecular-level structure of the polymer are observed by XRD and micro-Raman spectroscopy after deformation. However, the strained surfaces are found to exhibit void and craze formation spanning the nano- to micrometer length scales by molecular dynamics simulations, SEM, UV-vis spectroscopy, and naked-eye observations. This suggests that material microstructure (voids and crazes) can govern the triboelectric charging behavior of materials.

  19. A new method to predict fatigue crack growth rate of materials based on average cyclic plasticity strain damage accumulation

    Institute of Scientific and Technical Information of China (English)

    Chen Long; Cai Lixun; Yao Di

    2013-01-01

    By introducing a fatigue blunting factor,the cyclic elasto-plastic Hutchinson-RiceRosengren (HRR) field near the crack tip under the cyclic loading is modified.And,an average damage per loading-cycle in the cyclic plastic deformation region is defined due to Manson-Coffin law.Then,according to the linear damage accumulation theory-Miner law,a new model for predicting the fatigue crack growth (FCG) of the opening mode crack based on the low cycle fatigue (LCF) damage is set up.The step length of crack propagation is assumed to be the size of cyclic plastic zone.It is clear that every parameter of the new model has clearly physical meaning which does not need any human debugging.Based on the LCF test data,the FCG predictions given by the new model are consistent with the FCG test results of Cr2Ni2MoV and X12CrMoWVNbN 10-1-1.What's more,referring to the relative researches,the good predictability of the new model is also proved on six kinds of materials.

  20. An Experimental Study on the Thermal Performance of Phase-Change Material and Wood-Plastic Composites for Building Roofs

    Directory of Open Access Journals (Sweden)

    Min Hee Chung

    2017-02-01

    Full Text Available We assessed the usefulness of phase-change material (PCM-based thermal plates fabricated from wood-plastic composites (WPCs in mitigating the urban heat island effect. The thermal performance of plates containing PCMs with two different melting temperatures and with two different albedo levels was evaluated. The results showed that the PCM with a melting temperature of 44 °C maintained lower surface and inner temperatures than the PCM with a melting temperature of 25 °C. Moreover, a higher surface albedo resulted in a lower surface temperature. However, the thermal performance of PCMs with different melting temperatures but the same surface albedo did not differ. Using PCM-based materials in roof finishing materials can reduce surface temperatures and improve thermal comfort.

  1. Synergistic Effects of Nucleating Agents and Plasticizers on the Crystallization Behavior of Poly(lactic acid

    Directory of Open Access Journals (Sweden)

    Xuetao Shi

    2015-01-01

    Full Text Available The synergistic effect of nucleating agents and plasticizers on the thermal and mechanical performance of PLA nanocomposites was investigated with the objective of increasing the crystallinity and balancing the stiffness and toughness of PLA mechanical properties. Calcium carbonate, halloysite nanotubes, talc and LAK (sulfates were compared with each other as heterogeneous nucleating agents. Both the DSC isothermal and non-isothermal studies indicated that talc and LAK were the more effective nucleating agents among the selected fillers. Poly(D-lactic acid (PDLA acted also as a nucleating agent due to the formation of the PLA stereocomplex. The half crystallization time was reduced by the addition of talc to about 2 min from 37.5 min of pure PLA by the isothermal crystallization study. The dynamic mechanical thermal study (DMTA indicated that nanofillers acted as both reinforcement fillers and nucleating agents in relation to the higher storage modulus. The plasticized PLA studied by DMTA indicated a decreasing glass transition temperature with the increasing of the PEG content. The addition of nanofiller increased the Young’s modulus. PEG had the plasticization effect of increasing the break deformation, while sharply decreasing the stiffness and strength of PLA. The synergistic effect of nanofillers and plasticizer achieved the balance between stiffness and toughness with well-controlled crystallization.

  2. Thermal behavior of epoxidized cardanol diethyl phosphate as novel renewable plasticizer for poly(vinyl chloride)

    Science.gov (United States)

    A novel plasticizer, epoxidized cardanol diethyl phosphate (ECEP), based on cardanol was synthesized. Chemical structure of ECEP was characterized by fourier transform infrared (FTIR), 1H-nuclear magnetic resonance(1H NMR) and 13C-nuclear magnetic resonance(13C NMR) spectroscopy. Effects of ECEP sub...

  3. Effect of r-value and texture on plastic deformation and necking behavior in interstitial-free steel sheets

    Science.gov (United States)

    Oh, Gyu-Jin; Lee, Kye-Man; Huh, Moo-Young; Park, Jin Eon; Park, Soo Ho; Engler, Olaf

    2017-01-01

    Three initial tensile specimens having different textures and, in consequence, different r-values were cut from a sheet of an interstitial-free steel. Using these specimens, the effect of r-value and texture on plastic deformation and the necking behavior were studied by tackling the strain state and texture during tensile tests. A reduced decrease in work hardening rate of tensile specimens with higher r-values led to a slower onset of diffuse necking which offers an increased uniform elongation. A slower reduction in thickness of specimens with a higher r-value provided a favorable resistance against onset of failure by localized necking.

  4. Compatibility Study for Plastic, Elastomeric, and Metallic Fueling Infrastructure Materials Exposed to Aggressive Formulations of Ethanol-blended Gasoline

    Energy Technology Data Exchange (ETDEWEB)

    Kass, Michael D [ORNL; Pawel, Steven J [ORNL; Theiss, Timothy J [ORNL; Janke, Christopher James [ORNL

    2012-07-01

    In 2008 Oak Ridge National Laboratory began a series of experiments to evaluate the compatibility of fueling infrastructure materials with intermediate levels of ethanol-blended gasoline. Initially, the focus was elastomers, metals, and sealants, and the test fuels were Fuel C, CE10a, CE17a and CE25a. The results of these studies were published in 2010. Follow-on studies were performed with an emphasis on plastic (thermoplastic and thermoset) materials used in underground storage and dispenser systems. These materials were exposed to test fuels of Fuel C and CE25a. Upon completion of this effort, it was felt that additional compatibility data with higher ethanol blends was needed and another round of experimentation was performed on elastomers, metals, and plastics with CE50a and CE85a test fuels. Compatibility of polymers typically relates to the solubility of the solid polymer with a solvent. It can also mean susceptibility to chemical attack, but the polymers and test fuels evaluated in this study are not considered to be chemically reactive with each other. Solubility in polymers is typically assessed by measuring the volume swell of the polymer exposed to the solvent of interest. Elastomers are a class of polymers that are predominantly used as seals, and most o-ring and seal manufacturers provide compatibility tables of their products with various solvents including ethanol, toluene, and isooctane, which are components of aggressive oxygenated gasoline as described by the Society of Automotive Engineers (SAE) J1681. These tables include a ranking based on the level of volume swell in the elastomer associated with exposure to a particular solvent. Swell is usually accompanied by a decrease in hardness (softening) that also affects performance. For seal applications, shrinkage of the elastomer upon drying is also a critical parameter since a contraction of volume can conceivably enable leakage to occur. Shrinkage is also indicative of the removal of one or more

  5. The development of biopolymer-based nanostructured materials : plastics, gels, IPNs and nanofoams

    NARCIS (Netherlands)

    Soest, van J.J.G.

    2006-01-01

    The ability to design products with structural features on a nanometric scale is a major technology driver in materials research Nanostructured materials are defined as materials with structural features on a sub-micron scale determining specific properties They consist of materials such as metals,

  6. The development of biopolymer-based nanostructured materials : plastics, gels, IPNs and nanofoams

    NARCIS (Netherlands)

    Soest, van J.J.G.

    2006-01-01

    The ability to design products with structural features on a nanometric scale is a major technology driver in materials research Nanostructured materials are defined as materials with structural features on a sub-micron scale determining specific properties They consist of materials such as metals,

  7. Elasto-plasticity and pore-pressure coupled analysis on the pullout behaviors of a plate anchor

    Directory of Open Access Journals (Sweden)

    Cun Hu

    2015-03-01

    Full Text Available A numerical method is proposed for the elasto-plasticity and pore-pressure coupled analysis on the pullout behaviors of a plate anchor. The bounding-surface plasticity (BSP model combined with Biot’s consolidation theory is employed to simulate the cyclic loading induced elasto-plastic deformation of the soil skeleton and the accompanying generation/dissipation of the excess pore water pressure. The suction force generated around the anchor due to the cyclic variation of the pore water pressure has much effect on the pullout capacity of the plate anchor. The calculated pullout capacity with the proposed method (i.e., the coupled analysis gets lower than that with the conventional total stress analysis for the case of long-term sustained loading, but slightly higher for the case of short-term monotonic loading. The cyclic loading induced accumulation of pore water pressure may result in an obvious decrease of the stiffness of the soil-plate anchor system.

  8. Increased Expression of the PI3K Enhancer PIKE Mediates Deficits in Synaptic Plasticity and Behavior in Fragile X Syndrome

    Directory of Open Access Journals (Sweden)

    Christina Gross

    2015-05-01

    Full Text Available The PI3K enhancer PIKE links PI3K catalytic subunits to group 1 metabotropic glutamate receptors (mGlu1/5 and activates PI3K signaling. The roles of PIKE in synaptic plasticity and the etiology of mental disorders are unknown. Here, we show that increased PIKE expression is a key mediator of impaired mGlu1/5-dependent neuronal plasticity in mouse and fly models of the inherited intellectual disability fragile X syndrome (FXS. Normalizing elevated PIKE protein levels in FXS mice reversed deficits in molecular and cellular plasticity and improved behavior. Notably, PIKE reduction rescued PI3K-dependent and -independent neuronal defects in FXS. We further show that PI3K signaling is increased in a fly model of FXS and that genetic reduction of the Drosophila ortholog of PIKE, CenG1A rescued excessive PI3K signaling, mushroom body defects, and impaired short-term memory in these flies. Our results demonstrate a crucial role of increased PIKE expression in exaggerated mGlu1/5 signaling causing neuronal defects in FXS.

  9. Increased expression of the PI3K enhancer PIKE mediates deficits in synaptic plasticity and behavior in fragile X syndrome.

    Science.gov (United States)

    Gross, Christina; Chang, Chia-Wei; Kelly, Seth M; Bhattacharya, Aditi; McBride, Sean M J; Danielson, Scott W; Jiang, Michael Q; Chan, Chi Bun; Ye, Keqiang; Gibson, Jay R; Klann, Eric; Jongens, Thomas A; Moberg, Kenneth H; Huber, Kimberly M; Bassell, Gary J

    2015-05-05

    The PI3K enhancer PIKE links PI3K catalytic subunits to group 1 metabotropic glutamate receptors (mGlu1/5) and activates PI3K signaling. The roles of PIKE in synaptic plasticity and the etiology of mental disorders are unknown. Here, we show that increased PIKE expression is a key mediator of impaired mGlu1/5-dependent neuronal plasticity in mouse and fly models of the inherited intellectual disability fragile X syndrome (FXS). Normalizing elevated PIKE protein levels in FXS mice reversed deficits in molecular and cellular plasticity and improved behavior. Notably, PIKE reduction rescued PI3K-dependent and -independent neuronal defects in FXS. We further show that PI3K signaling is increased in a fly model of FXS and that genetic reduction of the Drosophila ortholog of PIKE, CenG1A rescued excessive PI3K signaling, mushroom body defects, and impaired short-term memory in these flies. Our results demonstrate a crucial role of increased PIKE expression in exaggerated mGlu1/5 signaling causing neuronal defects in FXS.

  10. Corrosion and mechanical behavior of materials for coal gasification applications

    Energy Technology Data Exchange (ETDEWEB)

    Natesan, K.

    1980-05-01

    A state-of-the-art review is presented on the corrosion and mechanical behavior of materials at elevated temperatures in coal-gasification environments. The gas atmosphere in coal-conversion processes are, in general, complex mixtures which contain sulfur-bearing components (H/sub 2/S, SO/sub 2/, and COS) as well as oxidants (CO/sub 2//CO and H/sub 2/O/H/sub 2/). The information developed over the last five years clearly shows sulfidation to be the major mode of material degradation in these environments. The corrosion behavior of structural materials in complex gas environments is examined to evaluate the interrelationships between gas chemistry, alloy chemistry, temperature, and pressure. Thermodynamic aspects of high-temperature corrosion processes that pertain to coal conversion are discussed, and kinetic data are used to compare the behavior of different commercial materials of interest. The influence of complex gas environments on the mechanical properties such as tensile, stress-rupture, and impact on selected alloys is presented. The data have been analyzed, wherever possible, to examine the role of environment on the property variation. The results from ongoing programs on char effects on corrosion and on alloy protection via coatings, cladding, and weld overlay are presented. Areas of additional research with particular emphasis on the development of a better understanding of corrosion processes in complex environments and on alloy design for improved corrosion resistance are discussed. 54 references, 65 figures, 24 tables.

  11. Production behavior of irradiation defects in solid breeder materials

    Energy Technology Data Exchange (ETDEWEB)

    Moriyama, Hirotake; Moritani, Kimikazu [Kyoto Univ. (Japan)

    1998-03-01

    The irradiation effects in solid breeder materials are important for the performance assessment of fusion reactor blanket systems. For a clearer understanding of such effects, we have studied the production behavior of irradiation defects in some lithium ceramics by an in-situ luminescence measurement technique under ion beam irradiation. The luminescence spectra were measured at different temperatures, and the temperature-transient behaviors of luminescence intensity were also measured. The production mechanisms of irradiation defects were discussed on the basis of the observations. (author)

  12. Dynamic behavior of particulate/porous energetic materials

    Science.gov (United States)

    Nesterenko, Vitali F.; Chiu, Po-Hsun; Braithwaite, C. H.; Collins, Adam; Williamson, David Martin; Olney, Karl L.; Benson, David; McKenzie, Francesca

    2012-03-01

    Dynamic behavior of particulate/porous energetic materials in a broad range of dynamic conditions (low velocity impact and explosively driven expansion of rings) is discussed. Samples of these materials were fabricated using Cold Isostatic Pressing and Hot Isostatic Pressing with and without vacuum encapsulation. The current interest in these materials is due to the combination of their high strength and output of energy under critical conditions of mechanical deformation. They may exhibit high compressive and tensile strength with the ability to undergo bulk distributed fracture resulting in small size reactive fragments. The mechanical properties of these materials and the fragment sizes produced by fracturing are highly sensitive to mesostructure. For example, the dynamic strength of Al-W composites with fine W particles is significantly larger than the strength of composites with coarse W particles at the same porosity. The morphology of W inclusions had a strong effect on the dynamic strength and fracture pattern. Experimental results are compared with numerical data.

  13. FINITE ELEMENT ANALYSIS OF SUBSTRATE LOCAL PLASTIC DEFORMATION INDUCED BY CRACKED THIN HARD FILM

    Institute of Scientific and Technical Information of China (English)

    Zhu Youli; Ro(z)niatowski K; Kurzydlowski K; Huang Yuanlin; Xu Binshi

    2004-01-01

    It has been postulated that, with tensile loading conditions, micro-cracks on thin hard film act as stress concentrators enhancing plastic deformation of the substrate material in their vicinity. Under favorable conditions the localized plastic flow near the cracks may turn into macroscopic plastic strain thus affects the plasticity behaviors of the substrate. This phenomenon is analyzed quantitatively with finite element method with special attention focused on the analysis and discussion of the effects of plastic work hardening rate, film thickness and crack depth on maximum plastic strain, critical loading stress and the size of the local plastic deformation zone. Results show that micro-cracks on thin hard film have unnegligible effects on the plasticity behaviors of the substrate material under tensile loading.

  14. Study the Cyclic Plasticity Behavior of 508 LAS under Constant, Variable and Grid-Load-Following Loading Cycles for Fatigue Evaluation of PWR Components

    Energy Technology Data Exchange (ETDEWEB)

    Mohanty, Subhasish [Argonne National Lab. (ANL), Argonne, IL (United States); Barua, Bipul [Argonne National Lab. (ANL), Argonne, IL (United States); Soppet, William K. [Argonne National Lab. (ANL), Argonne, IL (United States); Majumdar, Saurin [Argonne National Lab. (ANL), Argonne, IL (United States); Natesan, Ken [Argonne National Lab. (ANL), Argonne, IL (United States)

    2016-09-01

    This report provides an update of an earlier assessment of environmentally assisted fatigue for components in light water reactors. This report is a deliverable in September 2016 under the work package for environmentally assisted fatigue under DOE’s Light Water Reactor Sustainability program. In an April 2016 report, we presented a detailed thermal-mechanical stress analysis model for simulating the stress-strain state of a reactor pressure vessel and its nozzles under grid-load-following conditions. In this report, we provide stress-controlled fatigue test data for 508 LAS base metal alloy under different loading amplitudes (constant, variable, and random grid-load-following) and environmental conditions (in air or pressurized water reactor coolant water at 300°C). Also presented is a cyclic plasticity-based analytical model that can simultaneously capture the amplitude and time dependency of the component behavior under fatigue loading. Results related to both amplitude-dependent and amplitude-independent parameters are presented. The validation results for the analytical/mechanistic model are discussed. This report provides guidance for estimating time-dependent, amplitude-independent parameters related to material behavior under different service conditions. The developed mechanistic models and the reported material parameters can be used to conduct more accurate fatigue and ratcheting evaluation of reactor components.

  15. Critical behavior of nanoemitter radiation in a percolation material

    Energy Technology Data Exchange (ETDEWEB)

    Burlak, G. [Centro de Investigacion en Ingenieria y Ciencias Aplicadas (Mexico)], E-mail: gburlak@uaem.mx; Diaz-de-Anda, A. [Centro de Investigacion en Ingenieria y Ciencias Aplicadas (Mexico); Karlovich, Yu. [Facultad de Ciencias, Universidad Autonoma del Estado de Morelos, Cuernavaca, Mor. Mexico (Mexico); Klimov, A.B. [Departamento de Fisica, Universidad de Guadalajara, Revolucion 1500, Guadalajara, Jalisco 44420 (Mexico)

    2009-04-06

    We studied the field radiation of disordered optical nanoemitters incorporated into three-dimensional (3D) spanning cluster in a percolation material. In supercritical state, the field intensity is large enough to produce a dynamic high-density coherent field. The resulting state becomes different for lossless and lossy mediums. For material with small losses the long-term coherence arises in the supercritical area close to the percolation threshold. As a result, the dynamic non-monotonic behavior of the field order parameter raises that allows to reach the optimal field intensity. This effect can allow optimization of the disordered optical nanostructures with incorporated radiating nanoemitters in various applications of information technology.

  16. The functional TiO2-biodegradable plastic composite material produced by HVOF spraying process.

    Science.gov (United States)

    Bang, Hee-Seon; Bang, Han-Sur; Lee, Yoon-Ki

    2007-11-01

    Photocatalytic TiO2 coatings on bio-degradable plastic(polybutylene succinate: PBS) were prepared by HVOF spraying using three kinds of agglomerated powders (P200: 200 nm, P30: 30 nm, P7: 7 nm). The microstructures of the coatings were characterized with SEM and XRD analysis, and the photocatalytic efficiency of the coatings was evaluated by photo degradation of gaseous acetaldehyde. For both the HVOF sprayed P200 and P30 coatings, high anatase ratio of 100% was achieved, regardless of the fuel gas pressure. On the other hand, for the HVOF sprayed P7 coating, the anatase ratio decreased from 100% to 49.1% with increasing fuel gas pressure. This decrease may be attributed to the much higher susceptibility to heat of the 7 nm agglomerated powders than the 30 nm and 200 nm agglomerated powders. In terms of the photocatalytic efficiency, HVOF sprayed P200 and P30 coatings seemed to outperform the P7 coatings because of their higher anatase ratios. However, the HVOF sprayed P7 coatings did not show photocatalytic activity possibly because of the extremely small reaction surface area to the photo-catalytic activity and low anatase ratio. Therefore, the present study found that functional PBS plastic with photocatalytic performance could be produced by spraying of ceramics such as TiO2.

  17. Characterisation and materials flow management for waste electrical and electronic equipment plastics from German dismantling centres.

    Science.gov (United States)

    Arends, Dagmar; Schlummer, Martin; Mäurer, Andreas; Markowski, Jens; Wagenknecht, Udo

    2015-09-01

    Waste electrical and electronic equipment is a complex waste stream and treatment options that work for one waste category or product may not be appropriate for others. A comprehensive case study has been performed for plastic-rich fractions that are treated in German dismantling centres. Plastics from TVs, monitors and printers and small household appliances have been characterised extensively. Based on the characterisation results, state-of-the-art treatment technologies have been combined to design an optimised recycling and upgrade process for each input fraction. High-impact polystyrene from TV casings that complies with the European directive on the restriction of hazardous substances (RoHS) was produced by applying continuous density separation with yields of about 60%. Valuable acrylonitrile butadiene styrene/polycarbonate can be extracted from monitor and printer casings by near-infrared-based sorting. Polyolefins and/or a halogen-free fraction of mixed styrenics can be sorted out by density separation from monitors and printers and small household appliances. Emerging separation technologies are discussed to improve recycling results. © The Author(s) 2015.

  18. Two distinct interneuron circuits in human motor cortex are linked to different subsets of physiological and behavioral plasticity.

    Science.gov (United States)

    Hamada, Masashi; Galea, Joseph M; Di Lazzaro, Vincenzo; Mazzone, Paolo; Ziemann, Ulf; Rothwell, John C

    2014-09-17

    How does a single brain region participate in multiple behaviors? Here we argue that two separate interneuron circuits in the primary motor cortex (M1) contribute differently to two varieties of physiological and behavioral plasticity. To test this in human brain noninvasively, we used transcranial magnetic stimulation (TMS) of M1 hand area to activate two independent sets of synaptic inputs to corticospinal neurons by changing the direction of current induced in the brain: posterior-to-anterior current (PA inputs) and anterior-to-posterior current (AP inputs). We demonstrate that excitability changes produced by repetitive activation of AP inputs depend on cerebellar activity and selectively alter model-based motor learning. In contrast, the changes observed with repetitive stimulation of PA inputs are independent of cerebellar activity and specifically modulate model-free motor learning. The findings are highly suggestive that separate circuits in M1 subserve different forms of motor learning.

  19. Relationship between anelastic and non-linear visco-plastic behavior of 316 stainless steel at low homologous temperature

    Energy Technology Data Exchange (ETDEWEB)

    Nir, N.; Huang, F.H.; Hart, E.W.; Li, C.Y.

    1976-05-01

    At low homologous temperature the plastic strain rate seems to be controlled largely by dislocation glide friction. However, since a sizeable fraction of the applied stress sigma is dissipated in overcoming the strong barriers due to dislocation tangles generated by strain hardening, only a portion of the applied stress is actually expended against the frictional resistance. A recent model for this process includes the role of dislocation pile-ups at the strong barriers. The pile-ups provide a mechanism for producing the internal back stresses that limit the effective frictional stress. The also appear in the deformation as a stored anelastic strain component. The resultant behavior at low temperature and high stress is similar to that proposed by Grupta and Li. The same model also predicts an anelastic behavior at low stress. Measurements at both high and low stress levels on 316 Stainless Steel have now shown that the predictions of the model are quantitatively consistent at both stress levels.

  20. 木塑复合材料的关键原材料概况%Overview of Key Raw Materials of Wood/Plastic Composites

    Institute of Scientific and Technical Information of China (English)

    高华; 黄海兵; 吕蕾; 高鹏

    2015-01-01

    介绍了木塑复合材料关键原料植物纤维、塑料和相容剂的概况及特性,在此基础上阐述了国内外近年来各类木塑复合材料的发展现状。%The brief information and features of the key raw materials of wood/plastic composites,i.e. plant fiber,plastics and compatibilizer,are introduced,based on which,the development status of various kinds of wood/plastic composites at home and abroad is summarized.

  1. Neural plasticity in hypocretin neurons: the basis of hypocretinergic regulation of physiological and behavioral functions in animals

    Directory of Open Access Journals (Sweden)

    Xiao-Bing eGao

    2015-10-01

    Full Text Available The neuronal system that resides in the perifornical and lateral hypothalamus (Pf/LH and synthesizes the neuropeptide hypocretin/orexin participates in critical brain functions across species from fish to human. The hypocretin system regulates neural activity responsible for daily functions (such as sleep/wake homeostasis, energy balance, appetite, etc and long-term behavioral changes (such as reward seeking and addiction, stress response, etc in animals. The most recent evidence suggests that the hypocretin system undergoes substantial plastic changes in response to both daily fluctuations (such as food intake and sleep-wake regulation and long-term changes (such as cocaine seeking in neuronal activity in the brain. The understanding of these changes in the hypocretin system is essential in addressing the role of the hypocretin system in normal physiological functions and pathological conditions in animals and humans. In this review, the evidence demonstrating that neural plasticity occurs in hypocretin-containing neurons in the Pf/LH will be presented and possible physiological behavioral, and mental health implications of these findings will be discussed.

  2. Achieving large macroscopic compressive plastic deformation and work-hardening-like behavior in a monolithic bulk metallic glass by tailoring stress distribution

    Science.gov (United States)

    Chen, L. Y.; Ge, Q.; Qu, S.; Jiang, Q. K.; Nie, X. P.; Jiang, J. Z.

    2008-05-01

    The limited plastic deformation and lack of work hardening seriously restrict the applications of bulk metallic glasses (BMGs). Here, large macroscopic compressive plastic deformation (over 15%) and work-hardening-like behavior were achieved in a monolithic BMG through tailoring loading stress distribution experimentally. Numerical analysis was also carried out to investigate the stress distribution under the same mechanical condition. It is shown that loading induced stress gradient is responsible for the achievement mentioned above.

  3. [Comparative research on the NIR and MIR micro-imaging of two similar plastic materials].

    Science.gov (United States)

    Wang, Dong; Ma, Zhi-Hong; Zhao, Liu; Pan, Li-Gang; Li, Xiao-Ting; Wang, Ji-Hua

    2011-09-01

    The NIR/MIR micro-imaging can supply not only the information of spectra, but also the information of spacial distribution of the sample, which is superior to the traditional NIR/MIR spectroscopy analysis. In the present paper, polyethylene and parafilm, with similar appearances, were regarded as the research objects, of which the NIR/MIR micro-imaging was collected. Chemical imaging (CI) and compare correlation imaging were carried out for the two materials respectively to discuss the imaging methods of the two materials. The result indicated that the differentiation of the CI values of the two materials in the NIR/MIR CI for material II was 0.004 8 and 0.254 8 respectively, while those in the NIR/MIR CI for material I were 0.002 6 and 0.326 5, respectively. Clear CI was acquired, and the two materials could be differentiated. The result of the compare correlation imagings indicated that the compare correlation imagings, in which the NIR/MIR spectra of the two materials were regarded as reference spectra respectively, can differentiate the two materials remarkably with clear imagings. In the compare correlation imagings of MIR micro-imaging, the difference of the correlation coefficients between the two materials' MIR spectra and the reference spectrum was more than 0.12, which showed a better imaging result; while a tiny difference of the correlation coefficients between the two materials' NIR spectra and the reference spectrum could be employed to show a clear imaging result for NIR compare correlation imaging so as to differentiate the two materials. This thesis, to some extent, can supply the reference to not only the rapid discrimination of the safety of the packaging material for agri-food, but also the imaging methods for NIR/MIR micro-imaging to differentiate the different materials.

  4. RHEOLOGICAL BEHAVIOR OF WOOD AND WOOD BASED MATERIALS

    Directory of Open Access Journals (Sweden)

    Rafael Rodolfo de Melo

    2010-05-01

    Full Text Available The wood, as well as other construction materials, presents changes in this stiffness and strength when submitted to a long time loading. This phenomenon is important in the analyses resistance capacity of structural materials. Mechanically, the wood behaves as aviscous-elastic solid. However, over time, the structural elements submitted to permanent or cyclic loading presents some deformation, which denotes a viscous-elastic behavior. This characteristic is influenced mainly on the intensity and duration of loading. In this study a review of rheological phenomenon is presented, showing up the causes and effects for a better understanding, which is essential for the appropriate and efficient use of the wood and wood composites as structural materials.

  5. APPLICATION OF INTEGRATION ALGORITHEMS FOR ELASTO-PLASTICITY CONSTITUTIVE MODEL FOR ANISOTROPIC SHEET MATERIALS

    Institute of Scientific and Technical Information of China (English)

    LIU Yanfang; SHI Fazhong; XU Xiangyang

    2006-01-01

    Two algorithms of computing stress increment by using the elasto-plasticity constitutive model are firstly formulated, which are the Euler integration method and the radial return method.Hill'48 anisotropic yield criterion is used. The Euler integration method can not obtain more accurate computation of the stress increment as the radial return method unless enough subintervals are taken,by which the Euler integration method will take excessive computing time. Without decreasing any accuracy, the radial return method can save much time. Finally, a square cup deep drawing from NUMISHEET'93 benchmarks is simulated with a self-developed code SheetForm in order to investigate the accuracy and efficiency of the radial return method.

  6. Discrete Element study of granular material - Bumpy wall interface behavior

    Science.gov (United States)

    El Cheikh, Khadija; Rémond, Sébastien; Pizette, Patrick; Vanhove, Yannick; Djelal, Chafika

    2016-09-01

    This paper presents a DEM study of a confined granular material sheared between two parallel bumpy walls. The granular material consists of packed dry spherical particles. The bumpiness is modeled by spheres of a given diameter glued on horizontal planes. Different bumpy surfaces are modeled by varying diameter or concentration of glued spheres. The material is sheared by moving the two bumpy walls at fixed velocity. During shear, the confining pressure applied on each bumpy wall is controlled. The effect of wall bumpiness on the effective friction coefficient and on the granular material behavior at the bumpy walls is reported for various shearing conditions. For given bumpiness and confining pressure that we have studied, it is found that the shear velocity does not affect the shear stress. However, the effective friction coefficient and the behavior of the granular material depend on the bumpiness. When the diameter of the glued spheres is larger than about the average grains diameter of the medium, the latter is uniformly sheared and the effective friction coefficient remains constant. For smaller diameters of the glued spheres, the effective friction coefficient increases with the diameter of glued spheres. The influence of glued spheres concentration is significant only for small glued spheres diameters, typically half of average particle diameter of the granular material. In this case, increasing the concentration of glued spheres leads to a decrease in effective friction coefficient and to shear localization at the interface. For different diameters and concentrations of glued spheres, we show that the effect of bumpiness on the effective friction coefficient can be characterized by the depth of interlocking.

  7. Extreme Spectroscopy: In situ nuclear materials behavior from optical data

    Energy Technology Data Exchange (ETDEWEB)

    Guimbretiere, G.; Canizares, A.; Raimboux, N.; Omnee, R.; Duval, F.; Ammar, M.R.; Simon, P. [CNRS - UPR3079 CEMHTI, Universite d' Orleans, 45071Orleans cedex 2 (France); Desgranges, L.; Mohun, R. [CEA, DEN, DEC, F-13108 Saint-Paul-Lez-Durance (France); Jegou, C.; Magnin, M. [CEA/DTCD/SECM/LMPA, Marcoule 30207 Bagnols Sur Ceze (France); Clavier, N.; Dacheux, N. [ICSM-UMR5257 CEA/CNRS/UM2/ENSCM, Marcoule, BP17171, 30207 Bagnols sur Ceze (France)

    2015-07-01

    In the nuclear industry, materials are regularly exposed to high temperature or/and irradiation and a better knowledge and understanding of their behavior under such extreme conditions is a key-point for improvements and further developments. Nowadays, Raman spectroscopy begins to be well known as a promising technique in the post mortem and remote characterization of nuclear materials exposed to extreme conditions. On this topic, at ANIMMA 2013 conference, we have presented some results about its implementation in the study of model or real nuclear fuel. However, the strength of Raman spectroscopy as in situ characterization tool is mainly its ability to be implemented remotely through optical fibers. Aware of this, implementation of other optical techniques can be considered in order to gain information not only on the structural dynamics of materials but also on the electronic charge carrier populations. In this paper, we propose to present our last advances in Raman characterization of nuclear materials and enlarge to the in situ use of complementary optical spectroscopies. Emphasis will be made on the information that can be gained to the behavior of the model fuel depleted UO{sub 2} under extreme conditions of high temperature and ionic irradiation: - In Situ Raman identification of the radiolysis alteration products of UO{sub 2} in contact with water under ionic irradiation. - In Situ Raman recording of the damaged dynamic of UO{sub 2} under inert atmosphere. - In Situ Raman and photo-luminescence study of virgin and damaged UO2 at high temperature. - In Situ study of electronic charge carriers' behavior in U{sub x}Th{sub 1-x}O{sub 2} solid solutions by mean of Iono- and Thermo- luminescence under and post- ionic irradiation. (authors)

  8. Synaptic plasticity in a recurrent neural network for versatile and adaptive behaviors of a walking robot

    DEFF Research Database (Denmark)

    Grinke, Eduard; Tetzlaff, Christian; Wörgötter, Florentin

    2015-01-01

    mechanisms with plasticity, exteroceptive sensory feedback, and biomechanics. The neural mechanisms consist of adaptive neural sensory processing and modular neural locomotion control. The sensory processing is based on a small recurrent neural network consisting of two fully connected neurons. Online...... correlation-based learning with synaptic scaling is applied to adequately change the connections of the network. By doing so, we can effectively exploit neural dynamics (i.e., hysteresis effects and single attractors) in the network to generate different turning angles with short-term memory for a walking...

  9. Characterisation and modelling of the plastic material behaviour and its application in sheet metal forming simulation

    NARCIS (Netherlands)

    Vegter, H.; ten Horn, Carel H.L.J.; An, Yuguo; Atzema, E.H.; Atzema, Eisso H.; Pijlman, H.H.; van den Boogaard, Antonius H.; Huetink, Han; Onate, E; Owen, D.R.J

    2003-01-01

    The application of simulation models in sheet metal forming in automotive industry has proven to be beneficial to reduce tool costs in the designing stage and for optimising current processes. Moreover, it is a promising tool for a material supplier to optimise material choice and development for

  10. Embedded Fibre Bragg Grating Sensor Response Model: Crack Growing Detection in Fibre Reinforced Plastic Materials

    DEFF Research Database (Denmark)

    Pereira, Gilmar Ferreira; Mikkelsen, Lars Pilgaard; McGugan, Malcolm

    2015-01-01

    This article presents a novel method to simulate the sensor output response of a Fibre Bragg Grating (FBG) sensor when embedded in a host material (Composite material or adhesive), during a crack growing/damage event. A finite element model of the crack growth mechanisms was developed, and differ...

  11. Comparison of United States and British Methods for Testing Plastic Materials

    Science.gov (United States)

    1976-09-01

    materials including cost, hot- molded and sheet materials. Two procedures, refractometric and microscopical, are proposed in order to cover satisfactorily...duplicability. The refractometric method, which is preferred, is based on the standard Abbe refractometer, almost universally used for liquids. For solids

  12. Single-molecule spectroscopy for plastic electronics: materials analysis from the bottom-up.

    Science.gov (United States)

    Lupton, John M

    2010-04-18

    pi-conjugated polymers find a range of applications in electronic devices. These materials are generally highly disordered in terms of chain length and chain conformation, besides being influenced by a variety of chemical and physical defects. Although this characteristic can be of benefit in certain device applications, disorder severely complicates materials analysis. Accurate analytical techniques are, however, crucial to optimising synthetic procedures and assessing overall material purity. Fortunately, single-molecule spectroscopic techniques have emerged as an unlikely but uniquely powerful approach to unraveling intrinsic material properties from the bottom up. Building on the success of such techniques in the life sciences, single-molecule spectroscopy is finding increasing applicability in materials science, effectively enabling the dissection of the bulk down to the level of the individual molecular constituent. This article reviews recent progress in single molecule spectroscopy of conjugated polymers as used in organic electronics.

  13. PKA and ERK, but not PKC, in the amygdala contribute to pain-related synaptic plasticity and behavior

    Directory of Open Access Journals (Sweden)

    Ramsey Cara

    2008-07-01

    Full Text Available Abstract The laterocapsular division of the central nucleus of the amygdala (CeLC has emerged as an important site of pain-related plasticity and pain modulation. Glutamate and neuropeptide receptors in the CeLC contribute to synaptic and behavioral changes in the arthritis pain model, but the intracellular signaling pathways remain to be determined. This study addressed the role of PKA, PKC, and ERK in the CeLC. Adult male Sprague-Dawley rats were used in all experiments. Whole-cell patch-clamp recordings of CeLC neurons were made in brain slices from normal rats and from rats with a kaolin/carrageenan-induced monoarthritis in the knee (6 h postinduction. Membrane-permeable inhibitors of PKA (KT5720, 1 μM; cAMPS-Rp, 10 μM and ERK (U0126, 1 μM activation inhibited synaptic plasticity in slices from arthritic rats but had no effect on normal transmission in control slices. A PKC inhibitor (GF109203x, 1 μM and an inactive structural analogue of U0126 (U0124, 1 μM had no effect. The NMDA receptor-mediated synaptic component was inhibited by KT5720 or U0126; their combined application had additive effects. U0126 did not inhibit synaptic facilitation by forskolin-induced PKA-activation. Administration of KT5720 (100 μM, concentration in microdialysis probe or U0126 (100 μM into the CeLC, but not striatum (placement control, inhibited audible and ultrasonic vocalizations and spinal reflexes of arthritic rats but had no effect in normal animals. GF109203x (100 μM and U0124 (100 μM did not affect pain behavior. The data suggest that in the amygdala PKA and ERK, but not PKC, contribute to pain-related synaptic facilitation and behavior by increasing NMDA receptor function through independent signaling pathways.

  14. An elastic-plastic iceberg material model considering temperature gradient effects and its application to numerical study

    Science.gov (United States)

    Shi, Chu; Hu, Zhiqiang; Luo, Yu

    2016-12-01

    To simulate the FPSO-iceberg collision process more accurately, an elastic-plastic iceberg material model considering temperature gradient effects is proposed and applied. The model behaves linearly elastic until it reaches the `Tsai-Wu' yield surfaces, which are a series of concentric elliptical curves of different sizes. Decreasing temperature results in a large yield surface. Failure criteria, based on the influence of accumulated plastic strain and hydrostatic pressure, are built into the model. Based on published experimental data on the relationship between depth and temperature in icebergs, three typical iceberg temperature profiles are proposed. According to these, ice elements located at different depths have different temperatures. The model is incorporated into LS-DYNA using a user-defined subroutine and applied to a simulation of FPSO collisions with different types of iceberg. Simulated area-pressure curves are compared with design codes to validate the iceberg model. The influence of iceberg shape and temperature on the collision process is analyzed. It is indicated that FPSO structural damage not only depends on the relative strength between the iceberg and the structure, but also depends on the local shape of the iceberg.

  15. An Elastic-Plastic Iceberg Material Model Considering Temperature Gradient Effects and its Application to Numerical Study

    Institute of Scientific and Technical Information of China (English)

    Chu Shi; Zhiqiang Hu; Yu Luo

    2016-01-01

    To simulate the FPSO-iceberg collision process more accurately, an elastic-plastic iceberg material model considering temperature gradient effects is proposed and applied. The model behaves linearly elastic until it reaches the ‘Tsai-Wu’ yield surfaces, which are a series of concentric elliptical curves of different sizes. Decreasing temperature results in a large yield surface. Failure criteria, based on the influence of accumulated plastic strain and hydrostatic pressure, are built into the model. Based on published experimental data on the relationship between depth and temperature in icebergs, three typical iceberg temperature profiles are proposed. According to these, ice elements located at different depths have different temperatures. The model is incorporated into LS-DYNA using a user-defined subroutine and applied to a simulation of FPSO collisions with different types of icebergs. Simulated area-pressure curves are compared with design codes to validate the iceberg model. The influence of iceberg shape and temperature on the collision process is analyzed. It is indicated that FPSO structural damage not only depends on the relative strength between the iceberg and the structure, but also depends on the local shape of the iceberg.

  16. Hydrophilic behavior of graphene and graphene-based materials.

    Science.gov (United States)

    Accordino, Sebastián R; Montes de Oca, Joan Manuel; Rodriguez Fris, J Ariel; Appignanesi, Gustavo A

    2015-10-21

    Graphene and the graphene-based materials like graphite, carbon nanotubes, and fullerenes are not only usually regarded as hydrophobic but also have been widely employed as paradigms for the investigation of the behavior of water under nonpolar confinement, a question of major concern for fields ranging from biology to materials design. However, some experimental and theoretical insights seem to contradict, at least partially, such a picture. In this work, we will provide firm evidence for a neat hydrophilic nature of graphene surfaces. Our molecular dynamics studies will demonstrate that parallel graphene sheets present a strong tendency to remain fully hydrated for moderately long times (even when the equilibrium state is indeed the collapse of the plates), and thus, they are less prone to self-assembly than model hydrophobic surfaces we shall employ as control which readily undergo a hydrophobic collapse. Potential of mean force calculations will indeed make evident that the solvent exerts a repulsive contribution on the self-assembly of graphene surfaces. Moreover, we shall also quantify graphene hydrophilicity by means of the calculation of water density at two pressures and water density fluctuations. This latter study has never been performed on graphene and represents a means both to confirm and to quantify its neat hydrophilic behavior. We shall also make evident the relevance of the mildly attractive water-carbon interactions, since their artificial weakening will be shown to revert from typically hydrophilic to typically hydrophobic behavior.

  17. Extension of the sorting instructions for household plastic packaging and changes in exposure to bioaerosols at materials recovery facilities.

    Science.gov (United States)

    Schlosser, O; Déportes, I Z; Facon, B; Fromont, E

    2015-12-01

    The aim of this study was to assess how extending the sorting instructions for plastic packaging would affect the exposure of workers working at materials recovery facility (MRF) to dust, endotoxins, fungi and bacteria, taking into consideration other factors that could have an influence on this exposure. Personal sampling was carried out at four MRFs during six sampling campaigns at each facility, both in sorting rooms and when the workers were involved in "mobile tasks" away from the rooms. The data was analysed by describing the extension of sorting instructions both using a qualitative variable (after vs before) and using data for the pots and trays recycling stream, including or excluding plastic film. Overall, before the extension of the sorting guidelines, the geometric mean of personal exposure levels in sorting rooms was 0.3mg/m(3) for dust, 27.7 EU/m(3) for endotoxins, 13,000 CFU/m(3) for fungi and 1800 CFU/m(3) for bacteria. When workers were involved in mobile tasks away from the rooms, these averages were 0.5mg/m(3), 25.7 EU/m(3), 28,000 CFU/m(3) and 5100 CFU/m(3) respectively.The application by households of instructions to include pots, trays and film with other recyclable plastic packaging led to an increase in exposure to endotoxins, fungi and bacteria at MRFs. For an increase of 0.5 kg per inhabitant per year in the pots, trays and film recycling stream, exposure in sorting rooms rose by a factor of 1.4-2.2, depending on the biological agent. Exposure during mobile tasks increased by a factor of 3.0-3.6. The age of the waste amplified the effect of the extension of sorting instructions on exposure to fungi, bacteria and endotoxins. Factors that had a significant influence on the exposure of workers to dust and/or bioaerosols included the presence of paper, newspapers and magazines in the sorted waste, the order in which incoming waste was treated and the quality of the ventilation system in the sorting rooms. The levels of exposure observed in

  18. γ-ray shielding behaviors of some nuclear engineering materials

    Energy Technology Data Exchange (ETDEWEB)

    Mann, Kulwinder Singh [Dept. of Physics, D.A.V. College, Punjab (India)

    2017-06-15

    The essential requirement of a material to be used for engineering purposes at nuclear establishments is its ability to attenuate the most penetrating ionizing radiations, gamma (γ)-rays. Mostly, high-Z materials such as heavy concrete, lead, mercury, and their mixtures or alloys have been used in the construction of nuclear establishments and thus termed as nuclear engineering materials (NEM). The NEM are classified into two categories, namely opaque and transparent, depending on their behavior towards the visible spectrum of EM waves. The majority of NEM are opaque. By contrast, various types of glass, which are transparent to visible light, are necessary at certain places in the nuclear establishments. In the present study, γ-ray shielding behaviors (GSB) of six glass samples (transparent NEM) were evaluated and compared with some opaque NEM in a wide range of energy (15 keV–15 MeV) and optical thickness (OT). The study was performed by computing various γ-ray shielding parameters (GSP) such as the mass attenuation coefficient, equivalent atomic number, and buildup factor. A self-designed and validated computer-program, the buildup factor-tool, was used for various computations. It has been established that some glass samples show good GSB, thus can safely be used in the construction of nuclear establishments in conjunction with the opaque NEM as well.

  19. On the Mechanical Behavior of Advanced Composite Material Structures

    Science.gov (United States)

    Vinson, Jack

    During the period between 1993 and 2004, the author, as well as some colleagues and graduate students, had the honor to be supported by the Office of Naval Research to conduct research in several aspects of the behavior of structures composed of composite materials. The topics involved in this research program were numerous, but all contributed to increasing the understanding of how various structures that are useful for marine applications behaved. More specifically, the research topics focused on the reaction of structures that were made of fiber reinforced polymer matrix composites when subjected to various loads and environmental conditions. This included the behavior of beam, plate/panel and shell structures. It involved studies that are applicable to fiberglass, graphite/carbon and Kevlar fibers imbedded in epoxy, polyester and other polymeric matrices. Unidirectional, cross-ply, angle ply, and woven composites were involved, both in laminated, monocoque as well as in sandwich constructions. Mid-plane symmetric as well as asymmetric laminates were studied, the latter involving bending-stretching coupling and other couplings that only can be achieved with advanced composite materials. The composite structures studied involved static loads, dynamic loading, shock loading as well as thermal and hygrothermal environments. One major consideration was determining the mechanical properties of composite materials subjected to high strain rates because the mechanical properties vary so significantly as the strain rate increases. A considerable number of references are cited for further reading and study for those interested.

  20. γ-Ray Shielding Behaviors of Some Nuclear Engineering Materials

    Directory of Open Access Journals (Sweden)

    Kulwinder Singh Mann

    2017-06-01

    Full Text Available The essential requirement of a material to be used for engineering purposes at nuclear establishments is its ability to attenuate the most penetrating ionizing radiations, gamma (γ-rays. Mostly, high-Z materials such as heavy concrete, lead, mercury, and their mixtures or alloys have been used in the construction of nuclear establishments and thus termed as nuclear engineering materials (NEM. The NEM are classified into two categories, namely opaque and transparent, depending on their behavior towards the visible spectrum of EM waves. The majority of NEM are opaque. By contrast, various types of glass, which are transparent to visible light, are necessary at certain places in the nuclear establishments. In the present study, γ-ray shielding behaviors (GSB of six glass samples (transparent NEM were evaluated and compared with some opaque NEM in a wide range of energy (15 keV–15 MeV and optical thickness (OT. The study was performed by computing various γ-ray shielding parameters (GSP such as the mass attenuation coefficient, equivalent atomic number, and buildup factor. A self-designed and validated computer-program, the buildup factor-tool, was used for various computations. It has been established that some glass samples show good GSB, thus can safely be used in the construction of nuclear establishments in conjunction with the opaque NEM as well.

  1. Reduction of endogenous kynurenic acid formation enhances extracellular glutamate, hippocampal plasticity, and cognitive behavior.

    Science.gov (United States)

    Potter, Michelle C; Elmer, Greg I; Bergeron, Richard; Albuquerque, Edson X; Guidetti, Paolo; Wu, Hui-Qiu; Schwarcz, Robert

    2010-07-01

    At endogenous brain concentrations, the astrocyte-derived metabolite kynurenic acid (KYNA) antagonizes the alpha 7 nicotinic acetylcholine receptor and, possibly, the glycine co-agonist site of the NMDA receptor. The functions of these two receptors, which are intimately involved in synaptic plasticity and cognitive processes, may, therefore, be enhanced by reductions in brain KYNA levels. This concept was tested in mice with a targeted deletion of kynurenine aminotransferase II (KAT II), a major biosynthetic enzyme of brain KYNA. At 21 days of age, KAT II knock-out mice had reduced hippocampal KYNA levels (-71%) and showed significantly increased performance in three cognitive paradigms that rely in part on the integrity of hippocampal function, namely object exploration and recognition, passive avoidance, and spatial discrimination. Moreover, compared with wild-type controls, hippocampal slices from KAT II-deficient mice showed a significant increase in the amplitude of long-term potentiation in vitro. These functional changes were accompanied by reduced extracellular KYNA (-66%) and increased extracellular glutamate (+51%) concentrations, measured by hippocampal microdialysis in vivo. Taken together, a picture emerges in which a reduction in the astrocytic formation of KYNA increases glutamatergic tone in the hippocampus and enhances cognitive abilities and synaptic plasticity. Our studies raise the prospect that interventions aimed specifically at reducing KYNA formation in the brain may constitute a promising molecular strategy for cognitive improvement in health and disease.

  2. Non-equilibrium grain boundaries in titanium nanostructured by severe plastic deformation: Computational study of sources of material strengthening

    DEFF Research Database (Denmark)

    Liu, Hongsheng; Mishnaevsky, Leon; Pantleon, Wolfgang

    2014-01-01

    A computational model of ultrafine grained (UFG) or nanostructured titanium (Ti), based on a finite element (FE) unit cell model of the material and a dislocation density based model of plastic deformation has been developed. FE simulations of tensile deformation of UFG Ti with different fractions...... and properties of the grain boundary (GB) phase have been carried out. The effect of different degrees of deviation from the equilibrium state of the grain boundaries (GBs) on the mechanical behaviour of nanostructured Ti have been investigated using the combined composite/dislocation dynamics based model....... In particular, the effects of different diffusion coefficients in the GB phase, of a high initial dislocation density in the grain boundaries, as well as of atomic scale precipitates are investigated for affecting the deformation behaviour of UFG or nanostructured Ti. © 2013 Elsevier B.V. All rights reserved....

  3. Recycling of Plastic

    DEFF Research Database (Denmark)

    Christensen, Thomas Højlund; Fruergaard, Thilde

    2011-01-01

    Plastic is produced from fossil oil. Plastic is used for many different products. Some plastic products like, for example, wrapping foil, bags and disposable containers for food and beverage have very short lifetimes and thus constitute a major fraction of most waste. Other plastic products like......, for example, gutters, window frames, car parts and transportation boxes have long lifetimes and thus appear as waste only many years after they have been introduced on the market. Plastic is constantly being used for new products because of its attractive material properties: relatively cheap, easy to form......, good strength and long durability. Recycling of plastic waste from production is well-established, while recycling of postconsumer plastic waste still is in its infancy. This chapter describes briefly how plastic is produced and how waste plastic is recycled in the industry. Quality requirements...

  4. Experimental Studies on Improved Plastic Bonded Explosives Materials (PBXs for Controlled Fragmentation Warheads

    Directory of Open Access Journals (Sweden)

    Elsharkawy Karim

    2017-01-01

    Full Text Available This paper describes formulations of plastic bonded explosives (PBXs based on three highly brisant explosives, namely 1,3,5-trinitro-1,3,5-triazinane (RDX, 1,3,5,7-tetranitro-1,3,5,7-tetrazocane (HMX and pentaerythritoltetranitrate (PETN with polyurethane (PU based on Glycidyl azide polymer (GAP as an energetic binder in comparison with composition-B, which used in the fragmentation warheads. The sensitivity and performance properties of different types of PBXs were evaluated by experimental results of prepared selected PBX compositions. Casting technique was used to prepare the selected compositions containing 14% PU based on GAP. It has been observed that the brisance of the PBX based on HMX was higher than that of comp-B by 21.3 %, the detonation velocity showed a remarkable increase of the order of 8480 (m/s while that of comp-B was 7638 (m/s. A controlled fragmentation warhead with an outer grooving warhead case of dimensions 100x35x4 mm was used and arena test was carried out to determine the lethal zone of the fragmentation warhead. The lethal zone obtained from arena test for PBX composition based on HMX named PBXHG4 was higher than that based on RDX or PETN, and than that of comp-B by 40%.

  5. Quality restoration of waste polyolefin plastic material through the dissolution-reprecipitation technique

    Directory of Open Access Journals (Sweden)

    Hadi Jasim Arkan

    2014-01-01

    Full Text Available This study examines the restoration of waste plastic polymers based on LDPE, HDPE or PP through dissolution/reprecipitation. Experimental conditions of the recycling process, including type of solvent/non-solvent, original polymer concentration and dissolution temperature were optimized. Results revealed that by using the different prepared solvents/non-solvents at various ratios and temperatures, the polymer recovery was always greater than 94%. The FTIR spectra and the thermal properties (melting point and crystallinity of the polymers before and after recycling were measured using Differential Scanning Calorimetry (DSC. Mechanical properties of the waste polymer before and after recycling were also measured. Besides small occasional deviations, the properties did not change. The tensile strength at maximum load was 7.1, 18.8, and 7.4 MPa for the recycled LDPE, HDPE and PP, respectively and 7.78, 18.54 and 7.86 MPa for the virgin polymer. For the waste, the strength was 6.2, 15.58 and 6.76 MPa.

  6. Characteristics of tritium release behavior from solid breeder materials

    Energy Technology Data Exchange (ETDEWEB)

    Kinjyo, T.; Nishikawa, M.; Yamashita, N.; Koyama, T.; Suematsu, K.; Fukada, S. [Graduate School of Engineering Science, Kyushu Univ., Fukuoka 812-8581 (Japan); Enoeda, M. [Naka Establishment, Japan Atomic Energy Agency, Ibaraki 319-1195 (Japan)

    2008-07-15

    A tritium release model has been developed by the present authors. The tritium release curves estimated by this tritium model give good agreement with experimental curves for Li {sub 4}SiO{sub 4}, Li{sub 2}TiO{sub 3}, Li{sub 2}ZrO{sub 3} or LiAlO{sub 2} under various purge gas conditions in our out-of-pile bred tritium release. The characteristics of tritium release behavior from various solid breeder materials carried out by us and in EXOTIC experiments at Petten are discussed in this study. (authors)

  7. Energy based model for temperature dependent behavior of ferromagnetic materials

    Science.gov (United States)

    Sah, Sanjay; Atulasimha, Jayasimha

    2017-03-01

    An energy based model for temperature dependent anhysteretic magnetization curves of ferromagnetic materials is proposed and benchmarked against experimental data. This is based on the calculation of macroscopic magnetic properties by performing an energy weighted average over all possible orientations of the magnetization vector. Most prior approaches that employ this method are unable to independently account for the effect of both inhomogeneity and temperature in performing the averaging necessary to model experimental data. Here we propose a way to account for both effects simultaneously and benchmark the model against experimental data from 5 K to 300 K for two different materials in both annealed (fewer inhomogeneities) and deformed (more inhomogeneities) samples. This demonstrates that this framework is well suited to simulate temperature dependent experimental magnetic behavior.

  8. Environmental Effect on Evolutionary Cyclic Plasticity Material Parameters of 316 Stainless Steel: An Experimental & Material Modeling Approach

    Energy Technology Data Exchange (ETDEWEB)

    Mohanty, Subhasish [Argonne National Lab. (ANL), Argonne, IL (United States); Soppet, William K. [Argonne National Lab. (ANL), Argonne, IL (United States); Majumdar, Saurin [Argonne National Lab. (ANL), Argonne, IL (United States); Natesan, Ken [Argonne National Lab. (ANL), Argonne, IL (United States)

    2014-09-20

    This report provides an update on an earlier assessment of environmentally assisted fatigue for light water reactor (LWR) materials under extended service conditions. This report is a deliverable under the work package for environmentally assisted fatigue in the Light Water Reactor Sustainability (LWRS) program. The overall objective of this LWRS project is to assess the degradation by environmentally assisted cracking/fatigue of LWR materials such as various alloy base metals and their welds used in reactor coolant system piping. This effort is to support the Department of Energy LWRS program for developing tools to understand the aging/failure mechanism and to predict the remaining life of LWR components for anticipated 60-80 year operation.

  9. Flex Fatigue Behavior Of Plastic Optical Fibers With Low Bending Cycles

    Directory of Open Access Journals (Sweden)

    Huang Juan

    2015-06-01

    Full Text Available Flex fatigue behaviour of plastic optical fibres (POFs with the diameters of 0.2 and 0.3 mm under different pretensions is measured with fatigue life curve by flexometer. The fatigue sensitivity coefficient is calculated by the linear fitting curve of normalised stress versus logarithm of bending cycles. The residual modulus is investigated during the flex fatigue processes. The results exhibit the exponential relationship between applied pretension and numbers of bending cycles at break. It is indicated that the flex fatigue of POFs might be sensitive with high swing angle or swing speed. There is an evident loss of modulus for two POFs with pretensions of 4 and 10% of ultimate tensile strength during 10-times bending cycles. The values of residual modulus of two POFs almost keep constant after 10-times bending cycles.

  10. The AAA+ ATPase, Thorase Regulates AMPA Receptor-Dependent Synaptic Plasticity and Behavior

    Science.gov (United States)

    Zhang, Jianmin; Wang, Yue; Chi, Zhikai; Keuss, Matthew J.; Pai, Ying-Min Emily; Kang, Ho Chul; Shin, Jooho; Bugayenko, Artem; Wang, Hong; Xiong, Yulan; Pletnikov, Mikhail V.; Mattson, Mark P.; Dawson, Ted M.; Dawson, Valina L.

    2011-01-01

    SUMMARY The synaptic insertion or removal of AMPA receptors (AMPAR) plays critical roles in the regulation of synaptic activity reflected in the expression of long-term potentiation (LTP) and long-term depression (LTD). The cellular events underlying this important process in learning and memory are still being revealed. Here we describe and characterize the AAA+ ATPase, Thorase, that regulates the expression of surface AMPAR. In an ATPase-dependent manner Thorase mediates the internalization of AMPAR by disassembling the AMPAR-GRIP1 complex. Following genetic deletion of Thorase, the internalization of AMPAR is substantially reduced, leading to increased amplitudes of miniature excitatory postsynaptic currents, enhancement of LTP and elimination of LTD. These molecular events are expressed as deficits in learning and memory in Thorase null mice. This study identifies an AAA+ ATPase that plays a critical role in regulating the surface expression of AMPAR and thereby regulates synaptic plasticity and learning and memory. PMID:21496646

  11. Learning and retrieval behavior in recurrent neural networks with pre-synaptic dependent homeostatic plasticity

    Science.gov (United States)

    Mizusaki, Beatriz E. P.; Agnes, Everton J.; Erichsen, Rubem; Brunnet, Leonardo G.

    2017-08-01

    The plastic character of brain synapses is considered to be one of the foundations for the formation of memories. There are numerous kinds of such phenomenon currently described in the literature, but their role in the development of information pathways in neural networks with recurrent architectures is still not completely clear. In this paper we study the role of an activity-based process, called pre-synaptic dependent homeostatic scaling, in the organization of networks that yield precise-timed spiking patterns. It encodes spatio-temporal information in the synaptic weights as it associates a learned input with a specific response. We introduce a correlation measure to evaluate the precision of the spiking patterns and explore the effects of different inhibitory interactions and learning parameters. We find that large learning periods are important in order to improve the network learning capacity and discuss this ability in the presence of distinct inhibitory currents.

  12. Fatigue Hardening Behavior of 1.5 GPa Grade Transformation-Induced Plasticity-Aided Martensitic Steel

    Science.gov (United States)

    Sugimoto, Koh-Ichi; Hojo, Tomohiko

    2016-11-01

    Low cycle fatigue hardening/softening behavior of a 0.2 pct C-1.5 pct Si-1.5 pct Mn-1.0 pct Cr-0.2 pct Mo-0.05 pct Nb transformation-induced plasticity (TRIP)-aided steel consisting of a wide lath martensite structure matrix and a narrow lath martensite-metastable retained austenite mixture was investigated. The steel exhibited notable fatigue hardening in the same way as TRIP-aided bainitic ferrite steel, although conventional martensitic steel such as SCM420 steel with the same tensile strength exhibited fatigue softening. The considerable fatigue hardening of this steel is believed to be associated mainly with the compressive internal stress that results from a difference in flow stress between the matrix and the martensite-austenite-like phase, with a small contribution from the strain-induced transformation and dislocation hardenings.

  13. Effects of Severe Plastic Deformation and Heat Treatment on Transformation Behavior of Explosively Welded Duplex TiNi-TiNi

    Institute of Scientific and Technical Information of China (English)

    Li Juntao; Zheng Yanjun; Cui Lishan

    2007-01-01

    The effects of severe plastic deformation and heat treatment on the transformation behavior of explosively welded duplex TiNi-TiNi shape memory alloys (SMAs) were investigated by differential scanning calorimeter (DSC) measurements. The explosively welded duplex TiNi-TiNi plate of 0.7 mm thickness was cold-rolled at room temperature to a 60% reduction in thickness and then annealed at different temperatures for different durations. The results showed that low temperature (623-723K) heat-treatment led to the crystallization of the amorphous region, and re-crystallization occurred in the specimens annealed at higher temperatures (over 873 K). Research indicated that the change of martensitic transformation temperature is due to the change of internal stresses with increasing heat treatment temperature. The change of annealing time also led to a change in martensitic transformation temperature, which was associated with the precipitation and decomposition of Ti3Ni4 in TiNi-1.

  14. Indentation Pileup Behavior of Ti-6Al-4V Alloy: Experiments and Nonlocal Crystal Plasticity Finite Element Simulations

    Science.gov (United States)

    Han, Fengbo; Tang, Bin; Yan, Xu; Peng, Yifei; Kou, Hongchao; Li, Jinshan; Deng, Ying; Feng, Yong

    2017-01-01

    This study reports on the indentation pileup behavior of Ti-6Al-4V alloy. Berkovich nanoindentation was performed on a specimen with equiaxed microstructure. The indented area was characterized by electron backscattered diffraction (EBSD) to obtain the indented grain orientations. Surface topographies of several indents were measured by atomic force microscopy (AFM). The pileup patterns on the indented surfaces show significant orientation dependence. Corresponding nonlocal crystal plasticity finite element (CPFE) simulations were carried out to predict the pileup patterns. Analysis of the cumulative shear strain distributions and evolutions for different slip systems around the indents found that the pileups are mainly caused by prismatic slip. The pileup patterns evolve with the loading and unloading process, and the change in pileup height due to the elastic recovery at unloading stage is significant. The density distributions of geometrically necessary dislocations (GNDs) around the indent were predicted. Simulation of nanoindentation on a tricrystal model was performed.

  15. Indentation Pileup Behavior of Ti-6Al-4V Alloy: Experiments and Nonlocal Crystal Plasticity Finite Element Simulations

    Science.gov (United States)

    Han, Fengbo; Tang, Bin; Yan, Xu; Peng, Yifei; Kou, Hongchao; Li, Jinshan; Deng, Ying; Feng, Yong

    2017-04-01

    This study reports on the indentation pileup behavior of Ti-6Al-4V alloy. Berkovich nanoindentation was performed on a specimen with equiaxed microstructure. The indented area was characterized by electron backscattered diffraction (EBSD) to obtain the indented grain orientations. Surface topographies of several indents were measured by atomic force microscopy (AFM). The pileup patterns on the indented surfaces show significant orientation dependence. Corresponding nonlocal crystal plasticity finite element (CPFE) simulations were carried out to predict the pileup patterns. Analysis of the cumulative shear strain distributions and evolutions for different slip systems around the indents found that the pileups are mainly caused by prismatic slip. The pileup patterns evolve with the loading and unloading process, and the change in pileup height due to the elastic recovery at unloading stage is significant. The density distributions of geometrically necessary dislocations (GNDs) around the indent were predicted. Simulation of nanoindentation on a tricrystal model was performed.

  16. Postnatal lead exposure and the cholinergic system: effects on cholinergically mediated behaviors and cholinergic development and plasticity in the hippocampus

    Energy Technology Data Exchange (ETDEWEB)

    Alfano, D.P.

    1982-01-01

    A review of previous evidence suggested the possibility of a functional association between the behavioral effect of early lead (Pb) exposure, hippocampal damage and cholinergic deficiency. To further assess this possibility, Long-Evans hooded rat pups were exposed to Pb for the first 25 postnatal days via the maternal milk. Beginning at 65 days of age, animals were tested on behavioral tasks sensitive to both Pb exposure and cholinergic deficiency. Exposure to both levels of Pb impaired passive avoidance acquisition and produced lower rates of spontaneous alternation. The anticholinergic scopolamine (0.4 mg/kg) impaired passive avoidance acquisition, lowered the rate of spontaneous alternation and decreased open field activity scores in control animals. At 30 days of age, the brains of High Pb and control animals were processed for acetylcholinesterase (AChE) histochemistry. Morphometric evaluation of the molecular layer of the hippocampal dentate gyrus indicated no effects of Pb on the development of the cholinergic innervation of this brain region. The results provide strong evidence for the involvement of deficient cholinergic functioning in the behavioral changes observed following postnatal Pb exposure. Further, these findings indicate that a decrease in neuroanatomical plasticity may be a critical brain mechanism underlying the learning deficits observed following exposure to Pb.

  17. Embedded Fibre Bragg Grating Sensor Response Model: Crack Growing Detection in Fibre Reinforced Plastic Materials

    DEFF Research Database (Denmark)

    Pereira, Gilmar Ferreira; Mikkelsen, Lars Pilgaard; McGugan, Malcolm

    2015-01-01

    This article presents a novel method to simulate the sensor output response of a Fibre Bragg Grating (FBG) sensor when embedded in a host material (Composite material or adhesive), during a crack growing/damage event. A finite element model of the crack growth mechanisms was developed...... the crack or non-uniform strain, and then identify the presence of such damage in the structure. Experimental tests were conducted in order to validate this concept and support the model. The FBG sensor response model was applied in a delamination of a Wind Turbine trailing edge, to demonstrate...

  18. LA-ICP/MS Analysis of Plastics as a Method to Support Polymer Assay in the Assessment of Materials for Low Background Detectors

    Energy Technology Data Exchange (ETDEWEB)

    Grate, Jay W.; Bliss, Mary; Farmer, Orville T.; Thomas, Linda MP; Liezers, Martin

    2016-03-12

    Ultra low-background radiation measurements are essential to several large-scale physics investigations, such as those involving neutrinoless double-beta decay, dark matter detection (such as SuperCDMS), and solar neutrino detection. There is a need for electrically and thermally insulating dielectric materials with extremely low-background radioactivity for detector construction. This need is best met with plastics. Most currently available structural plastics have milliBecquerel-per-kilogram total intrinsic radioactivity. Modern low-level detection systems require a large variety of plastics with low microBecquerel-per-kilogram levels. However, the assay of polymer materials for extremely low levels of radioactive elements, uranium and thorium in particular, presents new challenges. It is only recently that any certified reference materials (CRMs) for toxic metals such as lead or cadmium in plastics have become available. However, there are no CRMs for uranium or thorium in thermoplastics. This paper discusses our assessment of the use of laser ablation (LA) for sampling and inductively coupled plasma mass spectrometry (ICP-MS) for analysis of polyethylene (PE) samples, with an emphasis on uranium determination. Using a CRM for lead in PE, we examine LA and ICP-MS parameters that determine whether the total atom efficiencies for uranium and lead are similar, and explore methods to use the lead content in a plastic as part of the process of estimating or determining the uranium content by LA-ICP-MS.

  19. S100B overexpression increases behavioral and neural plasticity in response to the social environment during adolescence.

    Science.gov (United States)

    Buschert, Jens; Hohoff, Christa; Touma, Chadi; Palme, Rupert; Rothermundt, Matthias; Arolt, Volker; Zhang, Weiqi; Ambrée, Oliver

    2013-11-01

    Genetic variants as well as increased serum levels of the neurotrophic factor S100B are associated with different psychiatric disorders. However, elevated S100B levels are also related to a better therapeutic outcome in psychiatric patients. The functional role of elevated S100B in psychiatric disorders is still unclear. Hence, this study was designed in order to elucidate the differential effects of S100B overexpression in interaction with chronic social stress during adolescence on emotional behavior and adult neurogenesis. S100B transgenic and wild-type mice were housed either in socially stable or unstable environments during adolescence, between postnatal days 28 and 77. In adulthood, anxiety-related behavior in the open field, dark-light, and novelty-induced suppression of feeding test as well as survival of proliferating hippocampal progenitor cells were assessed. S100B transgenic mice revealed significantly reduced anxiety-related behavior in the open field compared to wild-types when reared in stable social conditions. In contrast, when transgenic mice grew up in unstable social conditions, their level of anxiety-related behavior was comparable to the levels of wild-type mice. In addition, S100B overexpressing mice from unstable housing conditions displayed higher numbers of surviving newborn cells in the adult hippocampus which developed into mature neurons. In conclusion, elevated S100B levels increase the susceptibility to environmental stimuli during adolescence resulting in more variable behavioral and neural phenotypes in adulthood. In humans, this increased plasticity might lead to both, enhanced risk for psychiatric disorders in negative environments and improved therapeutic outcome in positive environments.

  20. Finite deformation analysis of crack tip opening in elastic-plastic materials and implications for fracture initiation

    Energy Technology Data Exchange (ETDEWEB)

    McMeeking, R M

    1976-05-01

    Analyses of the stress and strain fields around smoothly blunting crack tips in both non-hardening and hardening elastic-plastic materials, under contained plane strain yielding and subject to mode I opening loads, have been carried out by a finite element method suitably formulated to admit large geometry changes. The results include the crack tip shape and near-tip deformation field, and the crack tip opening displacement has been related to a parameter of the applied load, the J-integral. The hydrostatic stresses near the crack tip are limited due to the lack of constraint on the blunted tip, limiting achievable stress levels except in a very small region around the crack tip in power law hardening materials. The J-integral is found to be path independent except very close to the crack tip in the region affected by the blunted tip. Models for fracture are discussed in the light of these results including one based on the growth of voids. The rate of void growth near the tip in hardening materials seems to be little different from the rate in non-hardening materials when measured in terms of crack tip opening displacement, which leads to a prediction of higher toughness in hardening materials. It is suggested that improvement of this model would follow from better understanding of void-void and void-crack coalescence and void nucleation, and some criteria and models for these are discussed. The implications of the finite element results for fracture criteria based on critical stress, strain or both are discussed with respect to transition of fracture mode and the angle of initial crack growth. Localization of flow is discussed as a possible fracture model and as a model for void-crack coalescence.

  1. Adsorption of albumin on prosthetic materials: implication for tribological behavior.

    Science.gov (United States)

    Serro, A P; Gispert, M P; Martins, M C L; Brogueira, P; Colaço, R; Saramago, B

    2006-09-01

    The orthopedic prosthesis used to substitute damaged natural joints are lubricated by a pseudosynovial fluid that contains biological macromolecules with potential boundary lubrication properties. Proteins are some of those macromolecules whose role in the lubrication process is not yet completely understood. In a previous work, we investigated the influence of the presence of albumin, the major synovial protein, upon the tribological behavior of three of the most used pairs of artificial joint materials: ultra high molecular weight polyethylene (UHMWPE) against counterfaces of alumina, CoCrMo alloy, and 316L stainless steel. Albumin was found to cause a significant decrease in the friction coefficient when the counterfaces were metallic because transfer of UHMWPE was avoided, but this effect was much weaker in the case of alumina. The objective of the present work was to look for an explanation for these differences in tribological behavior in terms of albumin adsorption. With this goal, studies on adsorption of bovine serum albumin (BSA) on the counterface materials, from a biological model fluid (Hanks' balanced salt solution), were carried out using radiolabeled albumin ((125)I-BSA), X-ray photoelectron spectroscopy, and atomic force microscopy. The conclusion from all techniques is that the driving force for albumin adsorption is higher on the metals than on alumina. These results confirm that the greater the amount of protein adsorbed on the counterface, the more efficient is the protection against the transfer of polymeric film to the counterface.

  2. Testing Plastic Deformations of Materials in the Introductory Undergraduate Mechanics Laboratory

    Science.gov (United States)

    Romo-Kroger, C. M.

    2012-01-01

    Normally, a mechanics laboratory at the undergraduate level includes an experiment to verify compliance with Hooke's law in materials, such as a steel spring and an elastic rubber band. Stress-strain curves are found for these elements. Compression in elastic bands is practically impossible to achieve due to flaccidity. A typical experiment for…

  3. A visco-elasto-plastic model for granular materials under simple shear conditions

    NARCIS (Netherlands)

    Redaelli, I.; di Prisco, C.; Vescovi, Dalila

    2016-01-01

    The numerical simulation of rapid landslides is quite complex mainly because constitutive models capable of simulating the mechanical behaviour of granular materials in the pre-collapse and post-collapse regimes are still missing. The goal of this paper is to introduce a constitutive model capable

  4. A visco-elasto-plastic model for granular materials under simple shear conditions

    NARCIS (Netherlands)

    Redaelli, I.; Prisco, di C.; Vescovi, D.

    2016-01-01

    The numerical simulation of rapid landslides is quite complex mainly because constitutive models capable of simulating the mechanical behaviour of granular materials in the pre-collapse and post-collapse regimes are still missing. The goal of this paper is to introduce a constitutive model capable o

  5. Elastic-plastic analysis of the SS-3 tensile specimen

    Energy Technology Data Exchange (ETDEWEB)

    Majumdar, S. [Argonne National Lab., IL (United States)

    1998-09-01

    Tensile tests of most irradiated specimens of vanadium alloys are conducted using the miniature SS-3 specimen which is not ASTM approved. Detailed elastic-plastic finite element analysis of the specimen was conducted to show that, as long as the ultimate to yield strength ratio is less than or equal to 1.25 (which is satisfied by many irradiated materials), the stress-plastic strain curve obtained by using such a specimen is representative of the true material behavior.

  6. Mechanical behavior of materials engineering methods for deformation, fracture, and fatigue

    CERN Document Server

    Dowling, Norman E

    2012-01-01

    For upper-level undergraduate engineering courses in Mechanical Behavior of Materials. Mechanical Behavior of Materials, 4/e introduces the spectrum of mechanical behavior of materials, emphasizing practical engineering methods for testing structural materials to obtain their properties, and predicting their strength and life when used for machines, vehicles, and structures. With its logical treatment and ready-to-use format, it is ideal for upper-level undergraduate students who have completed elementary mechanics of materials courses.

  7. Operant behavior to obtain palatable food modifies neuronal plasticity in the brain reward circuit.

    Science.gov (United States)

    Guegan, Thomas; Cutando, Laura; Ayuso, Eduard; Santini, Emanuela; Fisone, Gilberto; Bosch, Fatima; Martinez, Albert; Valjent, Emmanuel; Maldonado, Rafael; Martin, Miquel

    2013-02-01

    Palatability enhances food intake by hedonic mechanisms that prevail over caloric necessities. Different studies have demonstrated the role of endogenous cannabinoids in the mesocorticolimbic system in controlling food hedonic value and consumption. We hypothesize that the endogenous cannabinoid system could also be involved in the development of food-induced behavioral alterations, such as food-seeking and binge-eating, by a mechanism that requires neuroplastic changes in the brain reward pathway. For this purpose, we evaluated the role of the CB1 cannabinoid receptor (CB1-R) in the behavioral and neuroplastic changes induced by operant training for standard, highly caloric or highly palatable isocaloric food using different genetics, viral and pharmacological approaches. Neuroplasticity was evaluated by measuring changes in dendritic spine density in neurons previously labeled with the dye DiI. Only operant training to obtain highly palatable isocaloric food induced neuroplastic changes in neurons of the nucleus accumbens shell and prefrontal cortex that were associated to changes in food-seeking behavior. These behavioral and neuroplastic modifications induced by highly palatable isocaloric food were dependent on the activity of the CB1-R. Neuroplastic changes induced by highly palatable isocaloric food are similar to those produced by some drugs of abuse and may be crucial in the alteration of food-seeking behavior leading to overweight and obesity.

  8. Effect of Plastic Anisotropy on the Formability of Aluminum 6016-T4 Sheet Material

    Science.gov (United States)

    KIM, Young-Suk; YANG, Seung-Han

    2017-05-01

    Sheet metal formed of lightweight materials such as aluminum sheeting has received great attention related to the reduction of vehicle emissions. This paper evaluates the anisotropic yield locus using Kuwabara's biaxial tensile tester and stretches formability using Hecker's hemispherical punch stretching test for aluminum 6016-T4 sheet material. The anisotropic yield locus of the Al6016-T4 sheet measured is fitted well by the modified Drucker yield function. Moreover the best fitting to the experimental stress-strain curve from the tensile test was obtained by taking an appropriate hardening model. Analytical study to predict the stretch formability by using Hora's Modified Maximum Force Criterion (MMFC) was performed. The predicted forming limit curves (FLC) based on various yield functions were compared with the experiments and discussed.

  9. Wood plastic composites from agro-waste materials: Analysis of mechanical properties.

    Science.gov (United States)

    Nourbakhsh, Amir; Ashori, Alireza

    2010-04-01

    This article presents the application of agro-waste materials (i.e., corn stalk, reed stalk, and oilseed stalk) in order to evaluate and compare their suitability as reinforcement for thermoplastics as an alternative to wood fibers. The effects of fiber loading and CaCO(3) content on the mechanical properties were also studied. Overall trend shows that with addition of agro-waste materials, tensile and flexural properties of the composites are significantly enhanced. Oilseed fibers showed superior mechanical properties due to their high aspect ratio and chemical characteristics. The order of increment in the mechanical properties of the composites is oilseed stalk >corn stalk>reed stalk at all fiber loadings. The tensile and flexural properties of the composite significantly decreased with increasing CaCO(3) content, due to the reduction of interface bond between the fiber and matrix. It can be concluded from this study that the used agro-waste materials are attractive reinforcements from the standpoint of their mechanical properties.

  10. New Opportunities in Developing Engineering Plastics

    Institute of Scientific and Technical Information of China (English)

    Yang Weicai

    2007-01-01

    @@ Owing to their excellent mechanical property, electric behavior, chemical resistance, heat resistance, abrasion resistance, size stability, weather resistance, lighter weight than metal materials and small energy consumption in molding, engineering plastics are extensively used in the sectors-electronic/electric, automobile, construction and office equipment.

  11. Modeling the Mechanical Behavior of Ceramic Matrix Composite Materials

    Science.gov (United States)

    Jordan, William

    1998-01-01

    Ceramic matrix composites are ceramic materials, such as SiC, that have been reinforced by high strength fibers, such as carbon. Designers are interested in using ceramic matrix composites because they have the capability of withstanding significant loads while at relatively high temperatures (in excess of 1,000 C). Ceramic matrix composites retain the ceramic materials ability to withstand high temperatures, but also possess a much greater ductility and toughness. Their high strength and medium toughness is what makes them of so much interest to the aerospace community. This work concentrated on two different tasks. The first task was to do an extensive literature search into the mechanical behavior of ceramic matrix composite materials. This report contains the results of this task. The second task was to use this understanding to help interpret the ceramic matrix composite mechanical test results that had already been obtained by NASA. Since the specific details of these test results are subject to the International Traffic in Arms Regulations (ITAR), they are reported in a separate document (Jordan, 1997).

  12. Behavior of radioactive materials and safety stock of contaminated sludge.

    Science.gov (United States)

    Tsushima, Ikuo

    2017-01-28

    The radioactive fallout from the Fukushima Dai-ichi nuclear power plant disaster in 2011 has flowed into and accumulated in many wastewater treatment plants (WWTPs) via sewer systems; this has had a negative impact on WWTPs in eastern Japan. The behavior of radioactive materials was analyzed at four WWTPs in the Tohoku and Kanto regions to elucidate the mechanism by which radioactive materials are concentrated during the sludge treatment process from July 2011 to March 2013. Furthermore, numerical simulations were conducted to study the safe handling of contaminated sewage sludge stocked temporally in WWTPs. Finally, a dissolution test was conducted by using contaminated incinerated ash and melted slag derived from sewage sludge to better understand the disposal of contaminated sewage sludge in landfills. Measurements indicate that a large amount of radioactive material accumulates in aeration tanks and is becoming trapped in the concentrated sludge during the sludge condensation process. The numerical simulation indicates that a worker's exposure around contaminated sludge is less than 1 µSv/h when maintaining an isolation distance of more than 10 m, or when shielding with more than 20-cm-thick concrete. The radioactivity level of the eluate was undetectable in 9 out of 12 samples; in the remaining three samples, the dissolution rates were 0.5-2.7%.

  13. Sustainable reverse logistics for household plastic waste

    OpenAIRE

    Bing, X

    2014-01-01

    Summary of the thesis titled “Sustainable Reverse Logistics for Household Plastic Waste” PhD Candidate: Xiaoyun Bing Recycled plastic can be used in the manufacturing of plastic products to reduce the use of virgin plastics material. The cost of recycled plastics is usually lower than that of virgin plastics. Therefore, it is environmentally and economically beneficial to improve the plastic recycling system to ensure more plastic waste from households is properly collected and pr...

  14. Flow behavior and plasticity of Ti-6Al-4V under different electrically assisted treatments

    Science.gov (United States)

    Jiang, Tianhao; Peng, Linfa; Yi, Peiyun; Lai, Xinmin

    2016-12-01

    Both electrically assisted tension (EAT) and electrically assisted pre-treatment tension (EAPT) were conducted to compare different effects on improving deformation resistance and ductility of Ti-6Al-4V. It is found EAPT obviously enhanced the ductility of Ti-6Al-4V compared with that obtained in EAT. In order to decouple the thermal effect from electro-plastic effect, thermally assisted tension (TAT) as well as thermally assisted pre-treatment tension (TAPT) were also conducted. The result indicates deformation mechanism of alpha phase with h.c.p crystal structure in Ti-6Al-4V was insensitive to electric current when current duty is less than 20%. However, the elevated temperature alone is insufficient to account for additional stress drop in the initial yielding stress observed in EAT and EAPT when current duty is higher than 20%. According to XRD investigation on specimens treated in original state, TAPT and EAPT, it is found electric current accelerates the annihilation of alpha phase and formation of beta phase in Ti-6Al-4V more effectively than the rising temperature does and such microstructure evolution also throws light on the improvement of flow stress and ductility observed in EAPT both experimentally and theoretically.

  15. Critical material attributes (CMAs) of strip films loaded with poorly water-soluble drug nanoparticles: I. Impact of plasticizer on film properties and dissolution.

    Science.gov (United States)

    Krull, Scott M; Patel, Hardik V; Li, Meng; Bilgili, Ecevit; Davé, Rajesh N

    2016-09-20

    Recent studies have demonstrated polymer films to be a promising platform for delivery of poorly water-soluble drug particles. However, the impact of critical material attributes, for example plasticizer, on the properties of and drug release from such films has yet to be investigated. In response, this study focuses on the impact of plasticizer and plasticizer concentration on properties and dissolution rate of polymer films loaded with poorly water-soluble drug nanoparticles. Glycerin, triacetin, and polyethylene glycol were selected as film plasticizers. Griseofulvin was used as a model Biopharmaceutics Classification System class II drug and hydroxypropyl methylcellulose was used as a film-forming polymer. Griseofulvin nanoparticles were prepared via wet stirred media milling in aqueous suspension. A depression in film glass transition temperature was observed with increasing plasticizer concentration, along with a decrease in film tensile strength and an increase in film elongation, as is typical of plasticizers. However, the type and amount of plasticizer necessary to produce strong yet flexible films had no significant impact on the dissolution rate of the films, suggesting that film mechanical properties can be effectively manipulated with minimal impact on drug release. Griseofulvin nanoparticles were successfully recovered upon redispersion in water regardless of plasticizer or content, even after up to 6months' storage at 40°C and 75% relative humidity, which contributed to similar consistency in dissolution rate after 6months' storage for all films. Good content uniformity (<4% R.S.D. for very small film sample size) was also maintained across all film formulations.

  16. Multisensory integration and behavioral plasticity in sharks from different ecological niches.

    Directory of Open Access Journals (Sweden)

    Jayne M Gardiner

    Full Text Available The underwater sensory world and the sensory systems of aquatic animals have become better understood in recent decades, but typically have been studied one sense at a time. A comprehensive analysis of multisensory interactions during complex behavioral tasks has remained a subject of discussion without experimental evidence. We set out to generate a general model of multisensory information extraction by aquatic animals. For our model we chose to analyze the hierarchical, integrative, and sometimes alternate use of various sensory systems during the feeding sequence in three species of sharks that differ in sensory anatomy and behavioral ecology. By blocking senses in different combinations, we show that when some of their normal sensory cues were unavailable, sharks were often still capable of successfully detecting, tracking and capturing prey by switching to alternate sensory modalities. While there were significant species differences, odor was generally the first signal detected, leading to upstream swimming and wake tracking. Closer to the prey, as more sensory cues became available, the preferred sensory modalities varied among species, with vision, hydrodynamic imaging, electroreception, and touch being important for orienting to, striking at, and capturing the prey. Experimental deprivation of senses showed how sharks exploit the many signals that comprise their sensory world, each sense coming into play as they provide more accurate information during the behavioral sequence of hunting. The results may be applicable to aquatic hunting in general and, with appropriate modification, to other types of animal behavior.

  17. Multisensory integration and behavioral plasticity in sharks from different ecological niches.

    Science.gov (United States)

    Gardiner, Jayne M; Atema, Jelle; Hueter, Robert E; Motta, Philip J

    2014-01-01

    The underwater sensory world and the sensory systems of aquatic animals have become better understood in recent decades, but typically have been studied one sense at a time. A comprehensive analysis of multisensory interactions during complex behavioral tasks has remained a subject of discussion without experimental evidence. We set out to generate a general model of multisensory information extraction by aquatic animals. For our model we chose to analyze the hierarchical, integrative, and sometimes alternate use of various sensory systems during the feeding sequence in three species of sharks that differ in sensory anatomy and behavioral ecology. By blocking senses in different combinations, we show that when some of their normal sensory cues were unavailable, sharks were often still capable of successfully detecting, tracking and capturing prey by switching to alternate sensory modalities. While there were significant species differences, odor was generally the first signal detected, leading to upstream swimming and wake tracking. Closer to the prey, as more sensory cues became available, the preferred sensory modalities varied among species, with vision, hydrodynamic imaging, electroreception, and touch being important for orienting to, striking at, and capturing the prey. Experimental deprivation of senses showed how sharks exploit the many signals that comprise their sensory world, each sense coming into play as they provide more accurate information during the behavioral sequence of hunting. The results may be applicable to aquatic hunting in general and, with appropriate modification, to other types of animal behavior.

  18. Harnessing Brain Plasticity through Behavioral Techniques to Produce New Treatments in Neurorehabilitation

    Science.gov (United States)

    Taub, Edward

    2004-01-01

    Basic behavioral neuroscience research with monkeys has given rise to an efficacious new approach to the rehabilitation of movement after stroke, cerebral palsy, traumatic brain injury, and other types of neurological injury in humans termed Constraint-Induced Movement therapy or CI therapy. For the upper extremity, the treatment involves…

  19. Plastic Surgery

    Science.gov (United States)

    ... Surgery? A Week of Healthy Breakfasts Shyness Plastic Surgery KidsHealth > For Teens > Plastic Surgery Print A A ... forehead lightened with a laser? What Is Plastic Surgery? Just because the name includes the word "plastic" ...

  20. Three-Dimensional Crystal Plasticity Finite Element Simulation of Hot Compressive Deformation Behaviors of 7075 Al Alloy

    Science.gov (United States)

    Li, Lei-Ting; Lin, Y. C.; Li, Ling; Shen, Lu-Ming; Wen, Dong-Xu

    2015-03-01

    Three-dimensional crystal plasticity finite element (CPFE) method is used to investigate the hot compressive deformation behaviors of 7075 aluminum alloy. Based on the grain morphology and crystallographic texture of 7075 aluminum alloy, the microstructure-based representative volume element (RVE) model was established by the pole figure inversion approach. In order to study the macroscopic stress-strain response and microstructural evolution, the CPFE simulations are performed on the established microstructure-based RVE model. It is found that the simulated stress-strain curves and deformation texture well agree with the measured results of 7075 aluminum alloy. With the increasing deformation degree, the remained initial weak Goss texture component tends to be strong and stable, which may result in the steady flow stress. The grain orientation and grain misorientation have significant effects on the deformation heterogeneity during hot compressive deformation. In the rolling-normal plane, the continuity of strain and misorientation can maintain across the low-angle grain boundaries, while the discontinuity of strain and misorientation is observed at the high-angle grain boundaries. The simulated results demonstrate that the developed CPFE model can well describe the hot compressive deformation behaviors of 7075 aluminum alloy under elevated temperatures.

  1. Mechanics of materials model

    Science.gov (United States)

    Meister, Jeffrey P.

    1987-01-01

    The Mechanics of Materials Model (MOMM) is a three-dimensional inelastic structural analysis code for use as an early design stage tool for hot section components. MOMM is a stiffness method finite element code that uses a network of beams to characterize component behavior. The MOMM contains three material models to account for inelastic material behavior. These include the simplified material model, which assumes a bilinear stress-strain response; the state-of-the-art model, which utilizes the classical elastic-plastic-creep strain decomposition; and Walker's viscoplastic model, which accounts for the interaction between creep and plasticity that occurs under cyclic loading conditions.

  2. Sorting Plastic Waste in Hydrocyclone

    Directory of Open Access Journals (Sweden)

    Ernestas Šutinys

    2011-02-01

    Full Text Available The article presents material about sorting plastic waste in hydrocyclone. The tests on sorting plastic waste were carried out. Also, the findings received from the performed experiment on the technology of sorting plastic waste are interpreted applying an experimental model of the equipment used for sorting plastics of different density.Article in Lithuanian

  3. Corrosion behavior of construction materials for ionic liquid hydrogen compressor

    DEFF Research Database (Denmark)

    Arjomand Kermani, Nasrin; Petrushina, Irina; Nikiforov, Aleksey Valerievich

    2016-01-01

    The corrosion behavior of various commercially available stainless steels and nickel-based alloys as possible construction materials for components which are in direct contact with one of five different ionic liquids was evaluated. The ionic liquids, namely: 1-ethyl-3-methylimidazolium triflate, 1...... liquid hydrogen compressor. An electrochemical cell was specially designed, and steady-state cyclic voltammetry was used to measure the corrosion resistance of the alloys in the ionic liquids at 23 °C, under atmospheric pressure. The results showed a very high corrosion resistance and high stability...... for all the alloys tested. The two stainless steels, AISI 316L and AISI 347 showed higher corrosion resistance compared to AISI 321 in all the ionic liquids tested. It was observed that small addition of molybdenum, tantalum, and niobium to the alloys increased the corrosion stability in the ionic liquids...

  4. Obesogenic diet intake during pregnancy programs aberrant synaptic plasticity and addiction-like behavior to a palatable food in offspring.

    Science.gov (United States)

    Camacho, Alberto; Montalvo-Martinez, Larisa; Cardenas-Perez, Robbi E; Fuentes-Mera, Lizeth; Garza-Ocañas, Lourdes

    2017-07-14

    Contextual food conditioned behaviors require plasticity of glutamatergic neurotransmission in the reward system, involving changes in the expression of including a-amino-3-hydroxy-5-methylisoxazole 4-propionate receptors (AMPA), N-methyl-d-aspartic acid (NMDA) and metabotropic glutamate 2,3 (mGlur 2,3). However, the role of changes in glutamatergic synaptic markers on energy-dense palatable food preference during development has not been described. Here, we determine the effect of nutritional programing during gestation on fat food choices using a conditioned place preference (CPP) test and an operant training response and its effect on glutamatergic markers in the nucleus accumbens (Nac) shell and prefrontal cortex (PFC). Our data showed that rats displayed preference for palatable fat food and an increase in caloric intake when compared to a chow diet. Notably, 74% of rats showing a preference for fat food intake correlate with a positive HFD-paired score whereas 26% failed to get HFD-conditioned. Also, male rats trained under an operant training response schedule (FR1, FR5 and PR) showed high and low responder groups to work for food. Notably, hypercaloric nutritional programing of female rats leads to exacerbation for reinforcers in female offspring compared to offspring from chow diet. Finally, we found that an operant training response to palatable reinforcers correlates with upregulation of mGlur 2,3 in the NAc shell and PFC of male rats and female offspring. Also, we found selective Nr1 upregulation in NAc shell and the PFC of female offspring. Our data suggest that nutritional programing by hypercaloric intake leads to incentive motivation to work for food and synaptic plasticity alteration in the mesolimbic system. Copyright © 2017 Elsevier B.V. All rights reserved.

  5. Application of plasticity theory to soil behavior : a new sand model

    OpenAIRE

    1983-01-01

    The representation of rheological soil behavior by constitutive equations is a now branch of soil mechanics which has been expanding for 30 years. Based on continuum mechanics, numerical methods (finite elements) and experimental techniques, this now discipline allows practicing engineers to solve complex geotechnical problems. Although all soils are constituted of discrete mineral particles, forces and displacements within them are represented by continuous stresses and strains. Most stress-...

  6. Behavioral and neural plasticity caused by early social experiences: the case of the honeybee

    Directory of Open Access Journals (Sweden)

    Andrés eArenas

    2013-08-01

    Full Text Available Cognitive experiences during the early stages of life play an important role in shaping future behavior. Behavioral and neural long-term changes after early sensory and associative experiences have been recently reported in the honeybee. This invertebrate is an excellent model for assessing the role of precocious experiences on later behavior due to its extraordinarily tuned division of labor based on age polyethism. These studies are mainly focused on the role and importance of experiences occurred during the first days of the adult lifespan, their impact on foraging decisions and their contribution to coordinate food gathering. Odor-rewarded experiences during the first days of honeybee adulthood alter the responsiveness to sucrose, making young hive bees more sensitive to assess gustatory features about the nectar brought back to the hive and affecting the dynamic of the food transfers and the propagation of food-related information within the colony as well. Early olfactory experiences lead to stable and long-term associative memories that can be successfully recalled after many days, even at foraging ages. Also they improve memorizing of new associative learning events later in life. The establishment of early memories promotes stable reorganization of the olfactory circuits inducing structural and functional changes in the antennal lobe. Early rewarded experiences have relevant consequences at the social level too, biasing dance and trophallaxis partner choice and affecting recruitment. Here, we revised recent results in bees´ physiology, behavior and sociobiology to depict how the early experiences affect their cognition abilities and neural-related circuits.

  7. Operant behavior to obtain palatable food modifies neuronal plasticity in the brain reward circuit

    OpenAIRE

    Guegan, Thomas, 1983-; Cutando, Laura; Ayuso, Eduard; Santini, Emanuela; Fisone, Gilberto; Bosch, Fatima; Martínez, Albert; Valjent, Emmanuel; Maldonado, Rafael; Martín Sánchez, Miquel, 1971-

    2013-01-01

    Palatability enhances food intake by hedonic mechanisms that prevail over caloric necessities. Different studies have demonstrated the role of endogenous cannabinoids in the mesocorticolimbic system in controlling food hedonic value and consumption. We hypothesize that the endogenous cannabinoid system could also be involved in the development of food-induced behavioral alterations, such as food-seeking and binge-eating, by a mechanism that requires neuroplastic changes in the brain reward pa...

  8. Plastic fish

    CERN Multimedia

    Antonella Del Rosso

    2015-01-01

    In terms of weight, the plastic pollution in the world’s oceans is estimated to be around 300,000 tonnes. This plastic comes from both land-based and ocean-based sources. A lecture at CERN by chemist Wolfgang Trettnak addressed this issue and highlighted the role of art in raising people’s awareness.   Artwork by Wolfgang Trettnak. Packaging materials, consumer goods (shoes, kids’ toys, etc.), leftovers from fishing and aquaculture activities… our oceans and beaches are full of plastic litter. Most of the debris from beaches is plastic bottles. “PET bottles have high durability and stability,” explains Wolfgang Trettnak, a chemist by education and artist from Austria, who gave a lecture on this topic organised by the Staff Association at CERN on 26 May. “PET degrades very slowly and the estimated lifetime of a bottle is 450 years.” In addition to the beach litter accumulated from human use, rivers bring several ki...

  9. Finite Element Modeling of the Behavior of Armor Materials Under High Strain Rates and Large Strains

    Science.gov (United States)

    Polyzois, Ioannis

    For years high strength steels and alloys have been widely used by the military for making armor plates. Advances in technology have led to the development of materials with improved resistance to penetration and deformation. Until recently, the behavior of these materials under high strain rates and large strains has been primarily based on laboratory testing using the Split Hopkinson Pressure Bar apparatus. With the advent of sophisticated computer programs, computer modeling and finite element simulations are being developed to predict the deformation behavior of these metals for a variety of conditions similar to those experienced during combat. In the present investigation, a modified direct impact Split Hopkinson Pressure Bar apparatus was modeled using the finite element software ABAQUS 6.8 for the purpose of simulating high strain rate compression of specimens of three armor materials: maraging steel 300, high hardness armor (HHA), and aluminum alloy 5083. These armor materials, provided by the Canadian Department of National Defence, were tested at the University of Manitoba by others. In this study, the empirical Johnson-Cook visco-plastic and damage models were used to simulate the deformation behavior obtained experimentally. A series of stress-time plots at various projectile impact momenta were produced and verified by comparison with experimental data. The impact momentum parameter was chosen rather than projectile velocity to normalize the initial conditions for each simulation. Phenomena such as the formation of adiabatic shear bands caused by deformation at high strains and strain rates were investigated through simulations. It was found that the Johnson-Cook model can accurately simulate the behavior of body-centered cubic (BCC) metals such as steels. The maximum shear stress was calculated for each simulation at various impact momenta. The finite element model showed that shear failure first occurred in the center of the cylindrical specimen and

  10. 增塑剂对PVC电缆料电性能的影响%Influences of plasticizers on the electrical properties of PVC cable materials

    Institute of Scientific and Technical Information of China (English)

    易碧霞

    2001-01-01

    介绍了DBP、TPP、DOP、TOTM、TCP、DIDP及M-50等增塑剂在不同用量时对PVC电缆料电性能的影响:随着增塑剂用量的增加,PVC电缆料的电性能一般呈下降趋势。实验发现TOTM和TCP两种增塑剂的电性能较优,其最佳用量为35~40份。%Influences of different using amount of plasticizers, such as DBP, TPP, DOP,TOTM, TCP, DIDP and M-50, on the electrical properties of PVC cable materials are introduced. Generally, with the increase of using amount of plasticizers, the electrical properties of PVC cable materials go down. It is found that the electrical property of PVC cable material with TOTM or TCP plasticizer is better, and that the optimum using amount of the above two kinds of plasticizer is 35~40 parts based on 100 parts PVC resin.

  11. Effect of Nanoclay on the Flexural Creep Behavior of Wood/Plastic Composites

    Science.gov (United States)

    Kord, B.; Sheykholeslami, A.; Najafi, A.

    2016-01-01

    The effect of nanoclay on the short-term flexural creep behavior of polypropylene/wood flour composites was investigated. The results obtained showed that the flexural strength and modulus increased with contentt of nanoclay up to 3 phc and then decreased. The fractional deflection and relative creep decreased with increasing content of nanoclay. X-ray diffraction patterns and transmission electron microscopy revealed that the nanocomposites formed were intercalated. Morphological findings testified that the samples containing 3 phc of nanoclay had the highest degree of intercalation and dispersion.

  12. Effects of natural enrichment materials on stress, memory and exploratory behavior in mice.

    Science.gov (United States)

    Acklin, Casey J; Gault, Ruth A

    2015-07-01

    Environmental enrichment is an essential component of laboratory animal housing that allows animals to engage in natural behaviors in an otherwise artificial setting. Previous research by the authors suggested that, compared with synthetic enrichment materials, natural materials were associated with lower stress levels in mice. Here, the authors compare the effects of different enrichment materials on stress, memory and exploratory behavior in Swiss Webster mice. Mice that were provided with natural enrichment materials had lower stress levels, better memory and greater exploratory behavior than did mice provided with synthetic enrichment materials or with no enrichment materials. These findings suggest that provision of natural enrichment materials can improve well-being of laboratory mice.

  13. Effect of material scatter on the plastic behavior and stretchability in sheet metal forming

    NARCIS (Netherlands)

    Wiebenga, J.H.; Atzema, E.H.; An, Y.G.; Vegter, H.; Boogaard, van den A.H.

    2014-01-01

    Robust design of forming processes is gaining attention throughout the industry. To analyze the robustness of a sheet metal forming process using Finite Element (FE) simulations, an accurate input in terms of parameter scatter is required. This paper presents a pragmatic, accurate and economic appro

  14. Informative document waste plastics

    NARCIS (Netherlands)

    Nagelhout D; Sein AA; Duvoort GL

    1989-01-01

    This "Informative document waste plastics" forms part of a series of "informative documents waste materials". These documents are conducted by RIVM on the indstruction of the Directorate General for the Environment, Waste Materials Directorate, in behalf of the program of

  15. The Histone H3K27 Demethylase UTX Regulates Synaptic Plasticity and Cognitive Behaviors in Mice

    Directory of Open Access Journals (Sweden)

    Gang-Bin Tang

    2017-08-01

    Full Text Available Histone demethylase UTX mediates removal of repressive trimethylation of histone H3 lysine 27 (H3K27me3 to establish a mechanistic switch to activate large sets of genes. Mutation of Utx has recently been shown to be associated with Kabuki syndrome, a rare congenital anomaly syndrome with dementia. However, its biological function in the brain is largely unknown. Here, we observe that deletion of Utx results in increased anxiety-like behaviors and impaired spatial learning and memory in mice. Loss of Utx in the hippocampus leads to reduced long-term potentiation and amplitude of miniature excitatory postsynaptic current, aberrant dendrite development and defective synapse formation. Transcriptional profiling reveals that Utx regulates a subset of genes that are involved in the regulation of dendritic morphology, synaptic transmission, and cognition. Specifically, Utx deletion disrupts expression of neurotransmitter 5-hydroxytryptamine receptor 5B (Htr5b. Restoration of Htr5b expression in newborn hippocampal neurons rescues the defects of neuronal morphology by Utx ablation. Therefore, we provide evidence that Utx plays a critical role in modulating synaptic transmission and cognitive behaviors. Utx cKO mouse models like ours provide a valuable means to study the underlying mechanisms of the etiology of Kabuki syndrome.

  16. Exercise but not (-)-epigallocatechin-3-gallate or β-alanine enhances physical fitness, brain plasticity, and behavioral performance in mice.

    Science.gov (United States)

    Bhattacharya, Tushar K; Pence, Brandt D; Ossyra, Jessica M; Gibbons, Trisha E; Perez, Samuel; McCusker, Robert H; Kelley, Keith W; Johnson, Rodney W; Woods, Jeffrey A; Rhodes, Justin S

    2015-06-01

    Nutrition and physical exercise can enhance cognitive function but the specific combinations of dietary bioactives that maximize pro-cognitive effects are not known nor are the contributing neurobiological mechanisms. Epigallocatechin-3-gallate (EGCG) is a flavonoid constituent of many plants with high levels found in green tea. EGCG has anti-inflammatory and anti-oxidant properties and is known to cross the blood brain barrier where it can affect brain chemistry and physiology. β-Alanine (B-ALA) is a naturally occurring β-amino acid that could increase cognitive functioning by increasing levels of exercise via increased capacity of skeletal muscle, by crossing the blood brain barrier and acting as a neurotransmitter, or by free radical scavenging in muscle and brain after conversion into carnosine. The objective of this study was to determine the effects of EGCG (~250mg/kg/day), B-ALA (~550mg/kg/day), and their combination with voluntary wheel running exercise on the following outcome measures: body composition, time to fatigue, production of new cells in the granule layer of the dentate gyrus of the hippocampus as a marker for neuronal plasticity, and behavioral performance on the contextual and cued fear conditioning tasks, as measures of associative learning and memory. Young adult male BALB/cJ mice approximately 2months old were randomized into 8 groups varying the nutritional supplement in their diet and access to running wheels over a 39day study period. Running increased food intake, decreased fat mass, increased time to exhaustive fatigue, increased numbers of new cells in the granule layer of the hippocampus, and enhanced retrieval of both contextual and cued fear memories. The diets had no effect on their own or in combination with exercise on any of the fitness, plasticity, and behavioral outcome measures other than B-ALA decreased percent body fat whereas EGCG increased lean body mass slightly. Results suggest that, in young adult BALB/cJ mice, a 39

  17. Exercise but not (-)-Epigallocatechin-3-gallate or β-Alanine enhances physical fitness, brain plasticity, and behavioral performance in mice

    Science.gov (United States)

    Bhattacharya, Tushar K.; Pence, Brandt D.; Ossyra, Jessica M.; Gibbons, Trisha E.; Perez, Samuel; McCusker, Robert H.; Kelley, Keith W.; Johnson, Rodney W.; Woods, Jeffrey A.; Rhodes, Justin S.

    2015-01-01

    Nutrition and physical exercise can enhance cognitive function but the specific combinations of dietary bioactives that maximize pro-cognitive effects are not known nor are the contributing neurobiological mechanisms. Epigallocatechin-3-gallate (EGCG) is a flavonoid constituent of many plants with high levels found in green tea. EGCG has anti-inflammatory and anti-oxidant properties and is known to cross the blood brain barrier where it can affect brain chemistry and physiology. β-alanine (B-ALA) is a naturally occurring β–amino acid that could increase cognitive functioning by increasing levels of exercise via increased capacity of skeletal muscle, by crossing the blood brain barrier and acting as a neurotransmitter, or by free radical scavenging in muscle and brain after conversion into carnosine. The objective of this study was to determine the effects of EGCG (∼ 250 mg/kg/day), B-ALA (∼550 mg/kg/day), and their combination with voluntary wheel running exercise on the following outcome measures: body composition, time to fatigue, production of new cells in the granule layer of the dentate gyrus of the hippocampus as a marker for neuronal plasticity, and behavioral performance on the contextual and cued fear conditioning tasks, as measures of associative learning and memory. Young adult male BALB/cJ mice approximately 2 months old were randomized into 8 groups varying the nutritional supplement in their diet and access to running wheels over a 39 day study period. Running increased food intake, decreased fat mass, increased time to exhaustive fatigue, increased numbers of new cells in the granule layer of the hippocampus, and enhanced retrieval of both contextual and cued fear memories. The diets had no effect on their own or in combination with exercise on any of the fitness, plasticity, and behavioral outcome measures other than B-ALA decreased percent body fat whereas EGCG increased lean body mass slightly. Results suggest that, in young adult BALB

  18. Comparison of Two Xenograft Materials Used in Sinus Lift Procedures: Material Characterization and In Vivo Behavior

    Directory of Open Access Journals (Sweden)

    María Piedad Ramírez Fernández

    2017-06-01

    Full Text Available Detailed information about graft material characteristic is crucial to evaluate their clinical outcomes. The present study evaluates the physico-chemical characteristics of two xenografts manufactured on an industrial scale deproteinized at different temperatures (non-sintered and sintered in accordance with a protocol previously used in sinus lift procedures. It compares how the physico-chemical properties influence the material’s performance in vivo by a histomorphometric study in retrieved bone biopsies following maxillary sinus augmentation in 10 clinical cases. An X-ray diffraction analysis revealed the typical structure of hydroxyapatite (HA for both materials. Both xenografts were porous and exhibited intraparticle pores. Strong differences were observed in terms of porosity, crystallinity, and calcium/phosphate. Histomorphometric measurements on the bone biopsies showed statistically significant differences. The physic-chemical assessment of both xenografts, made in accordance with the protocol developed on an industrial scale, confirmed that these products present excellent biocompatibilitity, with similar characteristics to natural bone. The sintered HA xenografts exhibited greater osteoconductivity, but were not completely resorbable (30.80 ± 0.88% residual material. The non-sintered HA xenografts induced about 25.92 ± 1.61% of new bone and a high level of degradation after six months of implantation. Differences in the physico-chemical characteristics found between the two HA xenografts determined a different behavior for this material.

  19. A Reverse Numerical Approach to Determine Elastic-plastic Properties of Multi-layer Material Systems with Flat Cylindrical Indenters

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    In the present study, the indentation testing with a flat cylindrical indenter on typical multi-layer material systems was simulated successfully by finite element method. The emphasis was put on the methods of extracting the yield stresses and strain-hardening modulus of upper and middle-layers of three-layer material systems from the indentation testing. The slope of the indentation depth to the applied indentation stress curve was found to have a turning point, which can be used to determine the yield stress of the upper-layer. Then, a different method was also presented to determine the yield stress of the middle-layer. This method was based on a set of assumed applied indentation stresses which were to be intersected by the experimental results in order to meet the requirement of having the experimental indentation depth. At last, a reverse numerical algorithm was explored to determine the yield stresses of upper and middle-layers simultaneously by using the indentation testing with two different size indenters. This method assumed two ranges of yield stresses to simulate the indentation behavior. The experimental depth behavior was used to intersect the simulated indentation behavior. And the intersection corresponded to the values of yield stresses of upper and middle-layers. This method was also used further to determine the strain-hardening modulus of upper and middle-layers simultaneously.

  20. Forming limit prediction using a self-consistent crystal plasticity framework: a case study for body-centered cubic materials

    Science.gov (United States)

    Jeong, Youngung; Pham, Minh-Son; Iadicola, Mark; Creuziger, Adam; Foecke, Timothy

    2016-06-01

    A rate-dependent self-consistent crystal plasticity model was incorporated with the Marciniak-Kuczyński model in order to study the effects of anisotropy on the forming limits of BCC materials. The computational speed of the model was improved by a factor of 24 when running the simulations for several strain paths in parallel. This speed-up enabled a comprehensive investigation of the forming limits of various BCC textures, such as γ , σ , α , η and ɛ fibers and a uniform (random) texture. These simulations demonstrate that the crystallographic texture has significant (both positive and negative) effects on the resulting forming limit diagrams. For example, the γ fiber texture, which is often sought through thermo-mechanical processing due to a high r-value, had the highest forming limit in the balanced biaxial strain path but the lowest forming limit under the plane strain path among the textures under consideration. A systematic investigation based on the results produced by the current model, referred to as ‘VPSC-FLD’, suggests that the r-value does not serve as a good measure of forming limit strain. However, model predictions show a degree of correlation between the r-value and the forming limit stress.

  1. Study on the Wettability and Tribological Behavior of Different Polymers as Bearing Materials for Cervical Prosthesis

    Science.gov (United States)

    Wang, Song; Song, Jian; Liao, Zhenhua; Liu, Yuhong; Zhang, Caixia; Liu, Weiqiang

    2015-06-01

    Tribological behaviors of four polymers (conventional and cross-linked UHMWPE, conventional and glass fiber-reinforced PEEK) articulated with Ti6Al4V ball were studied under both dry sliding and 25% bovine serum lubrication. The hardness, static contact angle, surface damage topography, and wear parameter of wear scar were tested. Both cross-linked process of UHMWPE and glass fiber-reinforced treatment of PEEK improved wettability while they did not increase hardness. PEEK revealed higher surface hardness and better wettability than UHMWPE. The dominant wear mechanisms for UHMWPE were plastic deformation and fatigue wear while the failure mechanisms were severe adhesive and abrasive wear for PEEK. Cross-linked process of UHMWPE could form multi-molecular arrangement and reduce stratification, also decreasing friction coefficient and wear rate in both dry sliding and lubrication conditions. However, glass fiber-reinforced treatment of PEEK only decreased its friction coefficient and wear rate in dry condition, which was closely related to the function and wear mechanism of glass fiber. Cross-linked UHMWPE revealed the lowest friction coefficient and wear rate under lubrication condition, which was attributed to the cross-linked treatment and the formation of both protein adsorption film and lubrication film. Hence, cross-linked UHMWPE may be an alternative polymer for use as artificial cervical disc bearing material when it articulated with Ti6Al4V.

  2. Thermal Viscoelastic Analysis of Plastic Components Considering Residual Stress

    Science.gov (United States)

    Choi, Chel Woo; Jeoung, Kab Sik; Moon, Hyung-Il; Kim, Heon Young

    Plastics is commonly used in consumer electronics because of it is high strength per unit mass and good productivity, but plastic components may often become distorted after injection molding due to residual stress after the filling, packing, and cooling processes. In addition, plastic deteriorates depending on various temperature conditions and the operating time, which can be characterized by stress relaxation and creep. The viscoelastic behavior of plastic materials in the time domain can be expressed by the Prony series using the ABAQUS commercial software package. This paper suggests a process for predicting post-production deformation under cyclic thermal loading. The process was applied to real plastic panels, and the deformation predicted by the analysis was compared to that measured in actual testing, showing the possibility of using this process for predicting the post-production deformation of plastic products under thermal loading.

  3. Elasto-Plastic Behavior of High RRR Niobium: Effects of Crystallographic Texture, Microstructure and Hydrogen Concentration

    Energy Technology Data Exchange (ETDEWEB)

    G.R. Myneni; S.R. Agnew

    2002-11-01

    Conventional assessments of the mechanical properties of polycrystalline high RRR niobium via tensile testing have revealed unusually low apparent Young's moduli and yield strength in annealed samples. These observations motivated the current investigation of a variety of possible contributors: crystallographic texture, grain size, and impurity concentration. It is shown that the crystallographic textures of a single lot of niobium are essentially unchanged by post-recrystallization anneals at temperatures up to 800 C. Ultrasonic measurements reveal that the elastic response is not degraded by annealing. Rather, the material's extremely low yield point gives the impression of a low elastic modulus during tensile testing.

  4. Novel technology of electroless Ni-W-P on plastics and its interface behavior

    Institute of Scientific and Technical Information of China (English)

    WANG Tian-xu; HU Yong-jun; MENG Ji-long

    2004-01-01

    The electroless Ni-W-P coatings on polyoxymethylene(POM) were prepared. The POM was pretreated by hot spraying Al powder on it. Before the electroless Ni-W-P deposition, the POM with Al coating was flash plated in alkaline bath. The mechanism of Ni-W-P deposition was studied and the technology was optimized. The XRD analysis shows that the "as-deposited" Ni-W-P plating has mixed crystalline structure. The hardness value of deposits is more than HV700. The abrasion resistance of deposits is six times more than that of POM. Bending test was used to determine the cohesion between the deposits and the substrates. SEM was used to study the behavior of surface abrasion and interface bonding condition. The reason for the excellent cohesion was interpreted.

  5. KEMAMPUAN GENTENG PLASTIK BERGELOMBANG (CORRUGATED PLASTIC SEBAGAI BIOFILTER PARTIKEL AMONIAK DAN BAHAN ORGANIK DI MEDIA BUDIDAYA DAN LIMBAH CAIR BUDIDAYA IKAN (Performance of Corrugated Plastic as Biofilter of Ammonia Particle and Organic Material

    Directory of Open Access Journals (Sweden)

    Muslim Muslim

    2010-07-01

    Full Text Available ABSTRAK Pertumbuhan budidaya ikan dalam beberapa dekade ini berkembang sangat pesat, hal ini karena permintaan akan ikan meningkat. Meningkatnya kegiatan budidaya ikan selalu diiringi dengan meningkatnya limbah yang dihasilkan. Hal ini akan sangat cepat berpengaruh bila sistem budidaya yang dipakai adalah semi intesif atau intensif. Limbah tersebut harus segera dihilangkan atau dikurangi, karena akan berdampak pada ikan yang dibudidaya dan lingkungan seperti sungai dan laut. Tujuan penelitian ini adalah ingin mengetahui kemampuan genteng plastik bergelombang mengurangi limbah yang dihasilkan budidaya ikan yaitu Total Suspended Sediment (TSS, Suspended Sediment (SS, amoniak dan bahan organik (COD. Dari hasil penelitian diperoleh bahwa air limbah budidaya ikan yang mengandung TSS, SS, amoniak dan bahan organik setelah dilewatkan dengan genteng plastik bergelombang konsentrasinya menurun dengan tingkat efisiensi pengurangan yang terjadi di dalam kolam ikan dan di luar kolam ikan adalah sebagai berikut: 74,51% dan 54,42% (TSS; 39,20% dan 49,12% (SS; 19,82% dan 14,2% (amoniak; dan 24,82% dan 22,47% (COD. Ternyata genteng plastik bergelombang mempunyai tingkat pengurangan (g/m3/hr dan tingkat pengurangan spesifik (mg/m2/hr terhadap kandungan amoniak lebih efektif bila dibandingkan dengan material lain seperti plastic rolls, scrub pads, pipa PVC dan lain sebagainya.   ABSTRACT Aquaculture has been developing rapidly during the last few decades; it is due to the increase of fish demand. Increasing aquaculture activities especially with semi-intensive and intensive system have significant effect on waste production, which has to be removed or to be reduced quickly because will effect on fish in rearing tank and environment when through away to environment such as river and sea. The objectives of this study were to know the capability of corrugated plastic to remove or to reduce wastes content produced by aquaculture activities, i.e, Total Suspended

  6. Wear resistance of thick diamond like carbon coatings against polymeric materials used in single screw plasticizing technology

    Science.gov (United States)

    Zitzenbacher, G.; Liu, K.; Forsich, C.; Heim, D.

    2015-05-01

    Wear on the screw and barrel surface accompany polymer single screw plasticizing technology from the beginning. In general, wear on screws can be reduced by using nitrided steel surfaces, fused armour alloys on the screw flights and coatings. However, DLC-coatings (Diamond Like Carbon) comprise a number of interesting properties such as a high hardness, a low coefficient of friction and an excellent corrosion resistance due to their amorphous structure. The wear resistance of about 50 µm thick DLC-coatings against polyamide 6.6, polybutylene terephthalate and polypropylene is investigated in this paper. The tribology in the solids conveying zone of a single screw extruder until the beginning of melting is evaluated using a pin on disc tribometer and a so called screw tribometer. The polymeric pins are pressed against coated metal samples using the pin on disc tribometer and the tests are carried out at a defined normal force and sliding velocity. The screw tribometer is used to perform tribological experiments between polymer pellets and rotating coated metal shafts simulating the extruder screw. Long term experiments were performed to evaluate the wear resistance of the DLC-coating. A reduction of the coefficient of friction can be observed after a frictional distance of about 20 kilometers using glass fibre reinforced polymeric materials. This reduction is independent on the polymer and accompanied by a black layer on the wear surface of the polymeric pins. The DLC-coated metal samples show an up to 16 µm deep wear track after the 100 kilometer test period against the glass fiber filled materials only.

  7. Plastic behavior of medium carbon vanadium microalloyed steel at temperatures near g « a transformation

    Directory of Open Access Journals (Sweden)

    Lourenço N.J.

    2001-01-01

    Full Text Available Dilatometric techniques were used to build the continuous cooling transformation (CCT diagram for a medium carbon microalloyed steel; the microstructure and hardness were determined at different cooling rates. The mechanical behavior of the steel in the austenite field and at temperatures approaching austenite to ferrite transformation was measured by means of hot torsion tests under isothermal and continuous cooling conditions. The no recrystallization temperatures, Tnr, and start of phase transformation, Ar3, were determined under continuous cooling condition using mean flow stress vs. inverse of absolute temperature diagrams. Interruption of static recrystallization within the interpass time in the austenite field indicated that the start of vanadium carbonitride precipitation occurred under 860 °C. Austenite transformation was found to start at around 710 °C, a temperature similar to that measured by dilatometry, suggesting that interphase precipitation delays the transformation of deformed austenite. Pearlite was observed at temperatures ranging from 650 °C to 600 °C, with the flow curves taking on a particular shape, i.e., stress rose sharply as strain was increased, reaching peak stress at low deformation, around 0.2, followed by an extensive softening region after peak stress.

  8. [Determination of 46 plasticizers in food contact polyvinyl chloride packaging materials and their migration into food simulants by gas chromatography-mass spectrometry].

    Science.gov (United States)

    Guo, Chunhai; Bo, Haibo; Duan, Wenzhong; Jia, Haitao; Chen, Ruichun; Ma, Yusong; Ai, Lianfeng

    2011-01-01

    A gas chromatography-mass spectrometry (GC-MS) method was developed for the determination of 46 plasticizers in food contact polyvinyl chloride (PVC) packaging materials and their migration into food simulants, i. e. water, 3% acetic acid, 10% ethanol and olive oil. Plasticizers in the PVC packaging materials, aqueous food simulants and olive oil food simulants were extracted by the dissolution-precipitation, liquid-liquid extraction and gel permeation chromatography (GPC) approaches, respectively. The extracts were analyzed by GC-MS in selective ion monitoring (SIM) mode and quantified using the external standard method. The cal-ibration curves were linear in the ranges of 0.1-2.0 mg/L with the correlation coefficients of 0.9910-0. 999 9. The limits of detection were from 0. 005 mg/kg to 0. 05 mg/kg ( S/N = 5 ). The recoveries at 3 spiked levels were 69.51%-107. 21% and the relative standard deviations (RSDs n = 6) ranged from 3.53% to 18.95%. These results show that this method is fast, sensitive and accurate for the qualitative and quantitative determination of plasticizers in food contact plastic products and 4 types of food simulants.

  9. Failure and Ejection Behavior of Concrete Materials under Internal Blast

    Directory of Open Access Journals (Sweden)

    Haifu Wang

    2016-01-01

    Full Text Available In order to investigate the failure and ejection behavior of concrete materials under internal blast, the default Riedel-Hiermaier-Thoma (RHT concrete model in AUTODYN and a meshfree processor called SPH are employed in this numerical simulation. It is shown that the failure mechanisms are significantly different in these damaged zones. Crushed zone is caused by shear failure while fractured zone is induced by tensile failure, and spalled zone is formed by a combination of shear and tensile failure. In addition, the ejection velocity distribution of the fragmented concrete mass on free surface is examined. The results indicate that the ejection velocity declines monotonously with the increase of the distance to symmetry axis of computational model. On the wall of the prefabricated borehole, two types of fragmented concrete mass are analyzed, and bottom initiation is recommended to eject the fragmented concrete mass effectively. Moreover, an algorithm of average ejection speed is developed to effectively estimate the drill capacity of high velocity, energetic (HE projectiles. At last, the validity of numerical simulation is verified by physical experiments.

  10. Correlation Between Domain Behavior and Magnetic Properties of Materials

    Energy Technology Data Exchange (ETDEWEB)

    Leib, Jeffrey Scott [Iowa State Univ., Ames, IA (United States)

    2003-01-01

    Correlation between length scales in the field of magnetism has long been a topic of intensive study. The long-term desire is simple: to determine one theory that completely describes the magnetic behavior of matter from an individual atomic particle all the way up to large masses of material. One key piece to this puzzle is connecting the behavior of a material's domains on the nanometer scale with the magnetic properties of an entire large sample or device on the centimeter scale. In the first case study involving the FeSiAl thin films, contrast and spacing of domain patterns are clearly related to microstructure and stress. Case study 2 most clearly demonstrates localized, incoherent domain wall motion switching with field applied along an easy axis for a square hysteresis loop. In case study 3, axis-specific images of the complex Gd-Si-Ge material clearly show the influence of uniaxial anisotropy. Case study 4, the only study with the sole intent of creating domain structures for imaging, also demonstrated in fairly simple terms the effects of increasing stress on domain patterns. In case study 5, it was proven that the width of magnetoresistance loops could be quantitatively predicted using only MFM. When all of the case studies are considered together, a dominating factor seems to be that of anisotropy, both magneticrostaylline and stress induced. Any quantitative bulk measurements heavily reliant on K coefficients, such as the saturation fields for the FeSiAl films, Hc in cases 1, 3, and 5, and the uniaxial character of the Gd5(Si2Ge2), transferred to and from the domain scale quite well. In-situ measurements of domain rotation and switching, could also be strongly correlated with bulk magnetic properties, including coercivity, Ms, and hysteresis loop shape. In most cases, the qualitative nature of the domain structures, when properly considered, matched quite well to what might have been expected

  11. Correlation Between Domain Behavior and Magnetic Properties of Materials

    Energy Technology Data Exchange (ETDEWEB)

    Jeffrey Scott Leib

    2003-05-31

    Correlation between length scales in the field of magnetism has long been a topic of intensive study. The long-term desire is simple: to determine one theory that completely describes the magnetic behavior of matter from an individual atomic particle all the way up to large masses of material. One key piece to this puzzle is connecting the behavior of a material's domains on the nanometer scale with the magnetic properties of an entire large sample or device on the centimeter scale. In the first case study involving the FeSiAl thin films, contrast and spacing of domain patterns are clearly related to microstructure and stress. Case study 2 most clearly demonstrates localized, incoherent domain wall motion switching with field applied along an easy axis for a square hysteresis loop. In case study 3, axis-specific images of the complex Gd-Si-Ge material clearly show the influence of uniaxial anisotropy. Case study 4, the only study with the sole intent of creating domain structures for imaging, also demonstrated in fairly simple terms the effects of increasing stress on domain patterns. In case study 5, it was proven that the width of magnetoresistance loops could be quantitatively predicted using only MFM. When all of the case studies are considered together, a dominating factor seems to be that of anisotropy, both magneticrostaylline and stress induced. Any quantitative bulk measurements heavily reliant on K coefficients, such as the saturation fields for the FeSiAl films, H{sub c} in cases 1, 3, and 5, and the uniaxial character of the Gd{sub 5}(Si{sub 2}Ge{sub 2}), transferred to and from the domain scale quite well. In-situ measurements of domain rotation and switching, could also be strongly correlated with bulk magnetic properties, including coercivity, M{sub s}, and hysteresis loop shape. In most cases, the qualitative nature of the domain structures, when properly considered, matched quite well to what might have been expected from theory and

  12. Laminate Analyses, Micromechanical Creep Response, and Fatigue Behavior of Polymer Matrix Composite Materials.

    Science.gov (United States)

    1982-12-01

    FATIGUE BEHAVIOR of POLYMER MATRIX COMPOSITE MATERIALS , 4 " .’* .. . . ". ... .. ... . . ~December 1982 41 .. FINAL REPORT .Army Research Office I I...DEPARTMENT REPORT UWME-DR-201-108-1 LAMINATE ANALYSES, MICROMECHANICAL CREEP RESPONSE, AND FATIGUE BEHAVIOR OF POLYMER MATRIX COMPOSITE MATERIALS...Behavior of Polymer Matrix Composite 16 Sept. 1979 - 30 Nov. 1982 Materials 6 PERFORMING ORG. REPORT NUMBER UWME-DR-201-108-1 7. AUTHOR(.) S. CONTRACT

  13. Performance Analysis of a Fiber Reinforced Plastic Oil Cooler Cover Considering the Anisotropic Behavior of the Fiber Reinforced PA66

    Directory of Open Access Journals (Sweden)

    Jian Wang

    2016-09-01

    Full Text Available In this paper, a simulation method based on an orthogonal anisotropic material is proposed. A numerical example using a simple plate is presented to show the difference in the static performance between the orthogonal anisotropic and the isotropic models. Comparing with the tested modal data of a diesel engine oil cooler cover made by glass fiber reinforced polyamide 66 (PA66, the proposed simulation method was confirmed to be much closer to reality than the general isotropic model. After that, a comprehensive performance comparison between the plastic oil cooler covers with the orthogonal anisotropic and the isotropic fiber orientations was carried out including a static deformation and stress analysis under a pressure-temperature coupled load, a forced response analysis, and an acoustic analysis under real operating conditions. The results show that the stress, the deformation, the peak vibration velocity, and the overall sound power level of the orthogonal anisotropic model are different from that obtained with the isotropic model. More importantly, the proposed method can provide a much more detailed frequency content compared to the isotropic model.

  14. Family material hardship and chinese adolescents' problem behaviors: a moderated mediation analysis

    National Research Council Canada - National Science Library

    Sun, Wenqiang; Li, Dongping; Zhang, Wei; Bao, Zhenzhou; Wang, Yanhui

    2015-01-01

    ...; we used the family stress model framework to investigate parental depression and negative parenting as potential mediators of the relation between family material hardship and adolescents' problem behaviors...

  15. Analytic method for material aging and quality analyzing to forecast long time stability of plastic micro heliostat components

    Science.gov (United States)

    Sauerborn, Markus; Liebenstund, Lena; Raue, Markus; Mang, Thomas; Herrmann, Ulf; Dueing, Andreas

    2017-06-01

    The Solar-Institute Jülich (SIJ) developed the micro heliostat system - a small sized heliostat - during the last years. One special performance of the micro heliostat is the option to integrate inexpensive plastic elements. The use of plastic as a cost reducer in the heliostat technique is also offering the chance to integrate complex designed components with a higher quality and special system function. The plastic for this application requires a high standing against UV radiation and thermal cycles with a daily extreme temperature variation. The temperature range inside the closed micro heliostat box can annually fluctuate between -20 °C and 80 °C in the worst case. Special aging tests were designed and performed for the first time in cooperation with the Institute for Applied Polymer Science (IAP) in order to identify and qualify a resistance plastic for the micro heliostat. This systematic plastic aging testing for the micro heliostat is introduced here. The tests were carried out under extreme ambient situations, which simulate the temperature and irradiation conditions that the heliostat has to stand for years. A particular climate of arid areas with continuous high solar radiation was defined for these tests. Two accelerating aging methods were adapted to reach adequate aging results in a reduced time. The aging of the investigated kinds of plastics were followed by tensile test, impact test, measuring Shore hardness, dynamic-mechanical analysis, differential scanning calorimetry and Fourier transform infrared spectroscopy to compare the different types of polymers. Parallel to these tests running real outdoor tests were performed, to control this accelerated aging. To have adequate conditions that the plastic in a micro heliostat has to stand, an identical closed test box with a glass cover was designed. The test samples inside the box were irradiated by the sun. The wanted forecast for the analyzed plastic was defined by the comparison of the real and

  16. Non-Newtonian behavior observed via dynamic rheology for various particle types in energetic materials and simulant composites

    Science.gov (United States)

    Choi, Jong Han; Lee, Sangmook; Lee, Jae Wook

    2017-02-01

    The rheological properties of polymer composites highly filled with different filler materials were examined using a stress-controlled rheometer with a parallel-plate configuration, for particle characterization of the filler materials in plastic (polymer) bonded explosive (PBX). Ethylene vinyl acetate (EVA) with dioctyl adipate (DOA) was used as the matrix phase, which was shown to exhibit Newtonian-like behavior. The dispersed phase consisted of one of two energetic materials, i.e., explosive cyclotrimethylene trinitramine (RDX) or cyclotetramethylene tetranitramine (HMX), or a simulant (Dechlorane) in a bimodal size distribution. Before the test, preshearing was conducted to identify the initial condition of each sample. All examined filled polymer specimens exhibited yield stress and shear-thinning behavior over the investigated frequency range. The complex viscosity dependence on the dynamic oscillation frequency was also fitted using an appropriate rheological model, suggesting the model parameters. Furthermore, the temperature dependency of the different filler particle types was determined for different filler volume fractions. These comparative studies revealed the influence of the particle characteristics on the rheological properties of the filled polymer.

  17. PRENATAL HYPOXIA IN DIFFERENT PERIODS OF EMBRYOGENESIS DIFFERENTIALLY AFFECTS CELL MIGRATION, NEURONAL PLASTICITY AND RAT BEHAVIOR IN POSTNATAL ONTOGENESIS

    Directory of Open Access Journals (Sweden)

    Dmitrii S Vasilev

    2016-03-01

    , affects formation of cortical cytoarchitecture, neuronal plasticity and behavior in postnatal ontogenesis which testify to cortical dysfunction. Hypoxia on E18 does not significantly affect cortical structure and parietal cortex-dependent behavioral tasks.

  18. Determination of Thirteen Plasticizers in Food Plastic Packaging Materials by Capillary Column Gas Chromatography%食品包装材料中13种增塑剂的毛细管气相色谱法测定

    Institute of Scientific and Technical Information of China (English)

    马康; 汤福寿; 何雅娟; 刘菲

    2011-01-01

    A capillary column gas chromatographic method was developed for the separation and determination of thirteen plasticizers, including dimethyl phthalate acid ester(DMP), diethyl phthalate acid ester( DEP), dipropyl phthalate acid ester( DnPP), diisobutyl phthalate acid ester( DIBP), dibutyl phthalate acid ester( DBP), diamyl phthalate acid ester( DAP), bisphenol A( BIA), di-n-hexyl phthalate acid ester(DHP), butyl benzyl phthalate acid ester(BBP), di-2-ethylhexyl adipate (DEHA), di(2-ethylhexyl) phthalate acid ester(DEHP), dioctyl phthalate acid ester(DOP) and dinonyl phthalate acid ester(DNP) in plastic packaging materials for foodstuff. The analytes were extracted with hexane from samples by Soxhlet extraction technique, then purified by silica solid phase extraction. Three key factors such as rinse solvent, eluting solvent and eluting volume were optimized. Hexane and toluene ( 1: 1, by volume) were used as rinse solvents, 2 mL ethyl acetate was used as eluting solvent. After filtration, the eluate was determined by gas chromatography with flame ionization detector(GC/FID). The calibration curves of thirteen plasticizers were linear in the range of O. 1 - 1 000 mg/L with detection limits of 0. 005 - 0. 030 mg/L. The spiked recoveries ranged from 90% to 116% with relative standard deviations of 2. 2% -4. 9%. The method was successfully applied in the determination of plasticizers in plastic packaging materials for foodstuff.%建立了索氏提取、固相萃取净化浓缩、毛细管气相色谱法测定塑料食品包装材料中13种增塑剂的方法.优化了固相萃取淋洗剂、洗脱剂和洗脱剂体积等参数.样品经正己烷索氏提取后,用硅胶小柱净化浓缩.以正己烷-甲苯为淋洗剂,2 mL乙酸乙酯为洗脱剂.过滤后的洗脱液用气相色谱仪分析.结果显示,13种增塑剂在0.1~1000 mg/L范围内呈良好线性,检出限为0.005~O.030 mg/L.样品的加标回收率为90%~116%,相对标准偏差为2.2%~4.9%.

  19. Probabilistic Multi-Factor Interaction Model for Complex Material Behavior

    Science.gov (United States)

    Abumeri, Galib H.; Chamis, Christos C.

    2010-01-01

    Complex material behavior is represented by a single equation of product form to account for interaction among the various factors. The factors are selected by the physics of the problem and the environment that the model is to represent. For example, different factors will be required for each to represent temperature, moisture, erosion, corrosion, etc. It is important that the equation represent the physics of the behavior in its entirety accurately. The Multi-Factor Interaction Model (MFIM) is used to evaluate the divot weight (foam weight ejected) from the external launch tanks. The multi-factor has sufficient degrees of freedom to evaluate a large number of factors that may contribute to the divot ejection. It also accommodates all interactions by its product form. Each factor has an exponent that satisfies only two points - the initial and final points. The exponent describes a monotonic path from the initial condition to the final. The exponent values are selected so that the described path makes sense in the absence of experimental data. In the present investigation, the data used were obtained by testing simulated specimens in launching conditions. Results show that the MFIM is an effective method of describing the divot weight ejected under the conditions investigated. The problem lies in how to represent the divot weight with a single equation. A unique solution to this problem is a multi-factor equation of product form. Each factor is of the following form (1 xi/xf)ei, where xi is the initial value, usually at ambient conditions, xf the final value, and ei the exponent that makes the curve represented unimodal that meets the initial and final values. The exponents are either evaluated by test data or by technical judgment. A minor disadvantage may be the selection of exponents in the absence of any empirical data. This form has been used successfully in describing the foam ejected in simulated space environmental conditions. Seven factors were required

  20. Sustainable reverse logistics for household plastic waste

    NARCIS (Netherlands)

    Bing, X.

    2014-01-01

    Summary of the thesis titled “Sustainable Reverse Logistics for Household Plastic Waste” PhD Candidate: Xiaoyun Bing Recycled plastic can be used in the manufacturing of plastic products to reduce the use of virgin plastics material. The cost of recycled plastics is usually lower than th

  1. Sustainable reverse logistics for household plastic waste

    NARCIS (Netherlands)

    Bing, X.

    2014-01-01

    Summary of the thesis titled “Sustainable Reverse Logistics for Household Plastic Waste” PhD Candidate: Xiaoyun Bing Recycled plastic can be used in the manufacturing of plastic products to reduce the use of virgin plastics material. The cost of recycled plastics is usually lower than

  2. Sustainable reverse logistics for household plastic waste

    NARCIS (Netherlands)

    Bing, X.

    2014-01-01

    Summary of the thesis titled “Sustainable Reverse Logistics for Household Plastic Waste” PhD Candidate: Xiaoyun Bing Recycled plastic can be used in the manufacturing of plastic products to reduce the use of virgin plastics material. The cost of recycled plastics is usually lower than th

  3. The Development of a SPME-GC/MS Method for the Analysis of VOC Emissions from Historic Plastic and Rubber Materials

    OpenAIRE

    Curran, K.; Underhill, M.; Gibson, L. T.; Strlic, M.

    2015-01-01

    Analytical methods have been developed for the analysis of VOC emissions from historic plastic and rubber materials using SPME-GC/MS. Parameters such as analysis temperature, sampling time and choice of SPME fibre coating were investigated and sampling preparation strategies explored, including headspace sampling in vials and in gas sampling bags. The repeatability of the method was evaluated. It was found that a 7 d accumulation time at room temperature, followed by sampling using a DVB/CAR/...

  4. Toxicology and occupational hazards of new materials and processes in metal surface treatment, powder metallurgy, technical ceramics, and fiber-reinforced plastics.

    Science.gov (United States)

    Midtgård, U; Jelnes, J E

    1991-12-01

    Many new materials and processes are about to find their way from the research laboratory into industry. The present paper describes some of these processes and provides an overview of possible occupational hazards and a list of chemicals used or produced in the processes. The technological areas that are considered are metal surface treatment (ion implantation, physical and chemical vapor deposition, plasma spraying), powder metallurgy, advanced technical ceramics, and fiber-reinforced plastics.

  5. USE OF PLASTIC MATERIAL AND TRIPLE SCAN IN THE PREPARATION OF SURGICAL GUIDES FOR THE DENTAL IMPLANT TREATMENT-CASE REPORT

    OpenAIRE

    Rosen Borisov

    2016-01-01

    The use of surgical guides in implant treatment increases the accuracy of the dental implant positioning compared with manual methods. Regardless of how they are made, deviations of implants from their intended position are established in all kinds of surgical guides. This article considers the use of plastic material and new scanning technique for the production of CAD/CAM surgical guides that aim to overcome the deficiencies of the currently applied technologies in the production of surgica...

  6. Application of Cross Linking Modified PE in Wood-Plastic Composite Materials%PE交联改性在木塑复合材料中的应用

    Institute of Scientific and Technical Information of China (English)

    刘淑红; 肖凯成

    2011-01-01

    Wood fiour/HDPE composite (WPC) with 70 % wood flour content as filler,waste HDPE as plastic matrix was prepared by compression method, the application of cross linking modified PE and compatibility technology in wood-plastic composite materials were comparative studied. The results showed that cross linking modified PE could significantly improve the strength of PE plastic matrix. The strength of wood-plastic composite material with the MAPE content of 1% , DCP content of 1.5 % were little less than that with MAPE content of 3 %. SEM analysis indicated that MAPE could improve the interface compatibility between wood flour and plastic, while cross linking modified PE had no help on improving the interface compatibility.%以木粉为填料,废旧 HDPE 为塑料基体,用压制成型法制备了木粉质量含量高达70%的木粉/HDPE复合材料,对比研究PE交联改性技术和MAPE增容技术在木塑复合材料中的应用.结果表明:PE的交联改性可明显提高PE塑料基体的强度,从而可以进一步提高整个复合材料的强度.当MAPE质量含量为l%,DCP质量含量为1.5%时,木塑复合材料的强度可与MAPE质量含量为3%的木塑复合材料相媲美.SEM分析表明:MAPE可以改善木粉与塑料的界面相容性,PE的交联改性对木塑复合材料界面的相容性的改善无贡献.

  7. Understanding bulk behavior of particulate materials from particle scale simulations

    Science.gov (United States)

    Deng, Xiaoliang

    Particulate materials play an increasingly significant role in various industries, such as pharmaceutical manufacturing, food, mining, and civil engineering. The objective of this research is to better understand bulk behaviors of particulate materials from particle scale simulations. Packing properties of assembly of particles are investigated first, focusing on the effects of particle size, surface energy, and aspect ratio on the coordination number, porosity, and packing structures. The simulation results show that particle sizes, surface energy, and aspect ratio all influence the porosity of packing to various degrees. The heterogeneous force networks within particle assembly under external compressive loading are investigated as well. The results show that coarse-coarse contacts dominate the strong network and coarse-fine contacts dominate the total network. Next, DEM models are developed to simulate the particle dynamics inside a conical screen mill (comil) and magnetically assisted impaction mixer (MAIM), both are important particle processing devices. For comil, the mean residence time (MRT), spatial distribution of particles, along with the collision dynamics between particles as well as particle and vessel geometries are examined as a function of the various operating parameters such as impeller speed, screen hole size, open area, and feed rate. The simulation results can help better understand dry coating experimental results using comil. For MAIM system, the magnetic force is incorporated into the contact model, allowing to describe the interactions between magnets. The simulation results reveal the connections between homogeneity of mixture and particle scale variables such as size of magnets and surface energy of non-magnets. In particular, at the fixed mass ratio of magnets to non-magnets and surface energy the smaller magnets lead to better homogeneity of mixing, which is in good agreement with previously published experimental results. Last but not

  8. Gradient Plasticity Model and its Implementation into MARMOT

    Energy Technology Data Exchange (ETDEWEB)

    Barker, Erin I.; Li, Dongsheng; Zbib, Hussein M.; Sun, Xin

    2013-08-01

    The influence of strain gradient on deformation behavior of nuclear structural materials, such as boby centered cubic (bcc) iron alloys has been investigated. We have developed and implemented a dislocation based strain gradient crystal plasticity material model. A mesoscale crystal plasticity model for inelastic deformation of metallic material, bcc steel, has been developed and implemented numerically. Continuum Dislocation Dynamics (CDD) with a novel constitutive law based on dislocation density evolution mechanisms was developed to investigate the deformation behaviors of single crystals, as well as polycrystalline materials by coupling CDD and crystal plasticity (CP). The dislocation density evolution law in this model is mechanism-based, with parameters measured from experiments or simulated with lower-length scale models, not an empirical law with parameters back-fitted from the flow curves.

  9. Effects of bituminous layer as backfill material on mechanical behavior in tunnel model

    OpenAIRE

    Moriyoshi, Akihiro; Takano, Shin-ei; Urata, Hiroyuki; Suzuki, Tetsuya; Yoshida, Takaki

    2001-01-01

    This paper describes the effects of bituminous material as a backfill material on mechanical behavior in model tunnel in laboratory. It is known that load spreading and relaxation of bituminous material are good properties. Then if we use bituminous material as a backfill material of tunnel, the tunnel will have waterproof, good load spreading property. We used new bituminous material (Aquaphalt) which can solidify in water. We conducted relaxation test in tension for new bituminous mat...

  10. Methylphenidate administration to adolescent rats determines plastic changes on reward-related behavior and striatal gene expression.

    Science.gov (United States)

    Adriani, Walter; Leo, Damiana; Greco, Dario; Rea, Monica; di Porzio, Umberto; Laviola, Giovanni; Perrone-Capano, Carla

    2006-09-01

    Administration of methylphenidate (MPH, Ritalin) to children with attention deficit hyperactivity disorder (ADHD) is an elective therapy, but raises concerns for public health, due to possible persistent neurobehavioral alterations. Wistar adolescent rats (30 to 46 day old) were administered MPH or saline (SAL) for 16 days, and tested for reward-related and motivational-choice behaviors. When tested in adulthood in a drug-free state, MPH-pretreated animals showed increased choice flexibility and economical efficiency, as well as a dissociation between dampened place conditioning and more marked locomotor sensitization induced by cocaine, compared to SAL-pretreated controls. The striatal complex, a core component of the natural reward system, was collected both at the end of the MPH treatment and in adulthood. Genome-wide expression profiling, followed by RT-PCR validation on independent samples, showed that three members of the postsynaptic-density family and five neurotransmitter receptors were upregulated in the adolescent striatum after subchronic MPH administration. Interestingly, only genes for the kainate 2 subunit of ionotropic glutamate receptor (Grik2, also known as KA2) and the 5-hydroxytryptamine (serotonin) receptor 7 (Htr7) (but not GABA(A) subunits and adrenergic receptor alpha1b) were still upregulated in adulthood. cAMP responsive element-binding protein and Homer 1a transcripts were modulated only as a long-term effect. In summary, our data indicate short-term changes in neural plasticity, suggested by modulation of expression of key genes, and functional changes in striatal circuits. These modifications might in turn trigger enduring changes responsible for the adult neurobehavioral profile, that is, altered processing of incentive values and a modified flexibility/habit balance.

  11. Constitutive modeling and computational implementation for finite strain plasticity

    Science.gov (United States)

    Reed, K. W.; Atluri, S. N.

    1985-01-01

    This paper describes a simple alternate approach to the difficult problem of modeling material behavior. Starting from a general representation for a rate-tpe constitutive equation, it is shown by example how sets of test data may be used to derive restrictions on the scalar functions appearing in the representation. It is not possible to determine these functions from experimental data, but the aforementioned restrictions serve as a guide in their eventual definition. The implications are examined for hypo-elastic, isotropically hardening plastic, and kinematically hardening plastic materials. A simple model for the evolution of the 'back-stress,' in a kinematic-hardening plasticity theory, that is entirely analogous to a hypoelastic stress-strain relation is postulated and examined in detail in modeling finitely plastic tension-torsion test. The implementation of rate-type material models in finite element algorithms is also discussed.

  12. Study on the plasticizer of microcapsules wall material of Xizang ghee%微胶囊化西藏酥油壁材增塑剂的研究

    Institute of Scientific and Technical Information of China (English)

    石燕; 郑为完; 刘凡; 葛辉

    2013-01-01

    By adding three different kinds of plasticizer into the maltodextrin microcapsule wall material respectively, a comprehensive study had been done to analyze the nature, property and usage amount of these three kinds of plasticizer.When this were added into the microcapsules wall material of Xizang ghee,the results showed that the plasticizer with collagen as its major component achieved the optimal performance. The relatively appropriate dosage was 16% .When this kind of plasticizer was added into the maltodextrin microcapsule wall material of Xizang ghee,the particle surface of the microcapsule of Xizang ghee product was smoother and the particle shape was better than the microcapsule of Xizang ghee product been produced by using traditional formula.%在微胶囊壁材麦芽糊精中分别添加三种不同性质的增塑剂,对三种增塑剂的性质、性能及用量进行了研究,并将其添加于西藏酥油微胶囊壁材中.结果表明:以胶原蛋白为主要成分的增塑剂性能最好,用量为16%.将其添加于壁材麦芽糊精中所制得的酥油微胶囊产品在颗粒形状及表面光滑度方面均优于用传统配方生产的酥油微胶囊产品.

  13. Synaptic Plasticity and Learning Behaviors Mimicked in Single Inorganic Synapses of Pt/HfOx/ZnOx/TiN Memristive System

    Science.gov (United States)

    Wang, Lai-Guo; Zhang, Wei; Chen, Yan; Cao, Yan-Qiang; Li, Ai-Dong; Wu, Di

    2017-01-01

    In this work, a kind of new memristor with the simple structure of Pt/HfOx/ZnOx/TiN was fabricated completely via combination of thermal-atomic layer deposition (TALD) and plasma-enhanced ALD (PEALD). The synaptic plasticity and learning behaviors of Pt/HfOx/ZnOx/TiN memristive system have been investigated deeply. Multilevel resistance states are obtained by varying the programming voltage amplitudes during the pulse cycling. The device conductance can be continuously increased or decreased from cycle to cycle with better endurance characteristics up to about 3 × 103 cycles. Several essential synaptic functions are simultaneously achieved in such a single double-layer of HfOx/ZnOx device, including nonlinear transmission properties, such as long-term plasticity (LTP), short-term plasticity (STP), and spike-timing-dependent plasticity. The transformation from STP to LTP induced by repetitive pulse stimulation is confirmed in Pt/HfOx/ZnOx/TiN memristive device. Above all, simple structure of Pt/HfOx/ZnOx/TiN by ALD technique is a kind of promising memristor device for applications in artificial neural network.

  14. Contribution to the theoretical study of the plastic strain localization in porous materials; Contribution a l'etude theorique de la localisation plastique dans les poreux

    Energy Technology Data Exchange (ETDEWEB)

    Willot, F

    2007-01-15

    This work presents a study in theoretical mechanics, in the classical framework of homogenization of heterogeneous media. It addresses a notoriously problematical situation of non-linear behavior and infinite contrast between two phases, one of which is a plastic solid phase and the other one, the porosity of the medium. Its aim is to investigate how plastic strain localization manifests itself at the level of the overall effective behavior of the medium in presence of pores, and in particular in the non-trivial limit of small porosity. This question, important to the understanding of ductile damage, is examined both numerically and theoretically, in the restricted situation of bi-dimensional systems, and using a deformation theory approach of plasticity. The numerical investigations consist of quasi-exact computations of the strain and stress fields in the voided medium, by means of a Fast Fourier Transform method, and using a particular Green function. The theoretical approach makes use of exact solutions, which can be obtained in particular cases of a periodic void lattice, as well as of a recent 'second-order' nonlinear homogenization approach. The virtues of the latter are evaluated in two steps, first by studying the underlying linear anisotropic homogenization step (an essential ingredient), then by studying the nonlinear step itself. The nature and significance of the singularities of the theory which appear in the limit of small porosity, confirmed by numerical computations, are partly elucidated. Finally, original observations are presented as to the relation between plastic deformation patterns in an ideal disordered medium, and some features of the macroscopic strain/stress curve. (author)

  15. Reciclagem de materiais plásticos: a importância da identificação correta Plastic materials recycling: the importance of the correct identification

    Directory of Open Access Journals (Sweden)

    Leda Coltro

    2008-06-01

    Full Text Available Muitos produtos de material plástico apresentam código de identificação (normalmente um número de 1 a 7 dentro de um triângulo de três setas e sob o mesmo uma abreviatura indicando o tipo de plástico do qual o produto é feito para auxiliar sua separação e posterior reciclagem e revalorização, contribuindo com a recuperação dos materiais plásticos descartados com o resíduo sólido urbano. Como as embalagens têm rotatividade alta, é importante que as mesmas apresentem o símbolo de identificação da resina a fim de facilitar a cadeia de reciclagem do plástico. Neste trabalho, foi feito um levantamento de dados sobre os símbolos de identificação dos materiais plásticos em um total de 177 embalagens plásticas rígidas para o acondicionamento de diversos produtos alimentícios e não alimentícios disponíveis no mercado brasileiro. Apesar da norma brasileira ABNT NBR 13230 já ter 14 anos, há ainda heterogeneidade na identificação das embalagens plásticas. Somente cerca de 80% das embalagens avaliadas apresentaram o símbolo de identificação da resina. Além disso, em alguns casos até 40% das embalagens apresentaram a identificação do material de forma incorreta. Portanto, ainda existe informação errônea no mercado brasileiro sobre o tipo de material da embalagem plástica (incluindo ausência do símbolo de identificação, bem como falta de informação sobre o símbolo correto de identificação da resina, sendo que ambos os fatores prejudicam a cadeia de reciclagem do plástico.Many plastic-based products show a resin identification code - usually a number from 1 to 7 inside a three-arrow triangle above a monogram - to identify the type of plastic used to make the product, for assisting in its separation and later recycling. In other words, to facilitate the recovery of plastics discarded with the municipal solid waste. Since packages have a high rotation, the presence of the resin identification code is

  16. Adsorption Behavior of Potassium Ion on Planting Materials

    Institute of Scientific and Technical Information of China (English)

    PAUNPASSANAN,Dechprasitthichoke; SUNANTA,Wangkarn; SAKDIPHON,Thiansem; PONLAYUTH,Sooksamiti; ORN-ANONG,Arquero

    2007-01-01

    Characterization of planting materials used as adsorbent has been studied in order to compare potassium ion adsorption on two types of planting materials, which are a fired planting material (FPM) made from a mixture of 4 kinds of wastes (bottom ash, flue gas desulfurization (FGD) gypsum, paddy soil and sawdust) formed and fired at 850 ℃ and the commercial planting material called "hydroball" (HDB) bought from Jatujak market, Bangkok. The physical characteristics of both types of planting materials indicate that the FPM has a larger specific surface area than the HDB. The factors affecting potassium adsorption on both the planting materials such as an equilibration time and some solid/solution ratios were investigated. The suitable equilibration time for the adsorption to reach an equilibrium on the FPM and HDB is one and two hours, respectively. The highest amounts of potassium ion adhavior on both the planting materials tends to correspond with the Freundlich isotherm.

  17. A density-dependent endochronic plasticity for powder compaction processes

    Science.gov (United States)

    Bakhshiani, A.; Khoei, A. R.; Mofid, M.

    This paper is concerned with the numerical modeling of powder cold compaction process using a density-dependent endochronic plasticity model. Endochronic plasticity theory is developed based on a large strain plasticity to describe the nonlinear behavior of powder material. The elastic response is stated in terms of hypoelastic model and endochronic plasticity constitutive equations are stated in unrotated frame of reference. A trivially incrementally objective integration scheme for rate constitutive equations is established. Algorithmic modulus consistent with numerical integration algorithm of constitutive equations is extracted. It is shown how the endochronic plasticity describes the behavior of powder material from the initial stage of compaction to final stage, in which material behaves as solid metals. It is also shown that some commonly used plasticity models for powder material can be derived as special cases of the proposed endochronic theory. Finally, the numerical schemes are examined for efficiency in the modeling of a plain bush, a rotational-flanged and a shaped tablet powder compaction component.

  18. Effect of viscosity on material behavior in friction stir welding process

    Institute of Scientific and Technical Information of China (English)

    ZHANG Hong-wu; ZHANG Zhao; BIE Jun; ZHOU Lei; CHEN Jin-tao

    2006-01-01

    Temperature-dependent elastic viscoplastic material model was used for the numerical simulation of the friction stir welding process. The non-elastic response of the rate-dependent material in the large deformation problems was calculated by using the closest point algorithm. The numerical results show that the shape of the equivalent plastic strain looks like onion rings and the spacing of the rings is approximately equal to the forward movement of the tool in one rotation. The equivalent plastic strain is increased with the increase of viscosity coefficient due to the increase of friction stress in the pin-plate interface. The region which is influenced by the rotating tool is decreased with the decrease of viscosity coefficient. The radial and circumferential stresses in front of the pin are greater than the ones behind the pin. This difference can be reduced with the decrease of viscosity.

  19. Recent advances in high performance poly(lactide): from “green” plasticization to super-tough materials via (reactive) compounding

    Science.gov (United States)

    Kfoury, Georgio; Raquez, Jean-Marie; Hassouna, Fatima; Odent, Jérémy; Toniazzo, Valérie; Ruch, David; Dubois, Philippe

    2013-01-01

    Due to its origin from renewable resources, its biodegradability, and recently, its industrial implementation at low costs, poly(lactide) (PLA) is considered as one of the most promising ecological, bio-sourced and biodegradable plastic materials to potentially and increasingly replace traditional petroleum derived polymers in many commodity and engineering applications. Beside its relatively high rigidity [high tensile strength and modulus compared with many common thermoplastics such as poly(ethylene terephthalate) (PET), high impact poly(styrene) (HIPS) and poly(propylene) (PP)], PLA suffers from an inherent brittleness, which can limit its applications especially where mechanical toughness such as plastic deformation at high impact rates or elongation is required. Therefore, the curve plotting stiffness vs. impact resistance and ductility must be shifted to higher values for PLA-based materials, while being preferably fully bio-based and biodegradable upon the application. This review aims to establish a state of the art focused on the recent progresses and preferably economically viable strategies developed in the literature for significantly improve the mechanical performances of PLA. A particular attention is given to plasticization as well as to impact resistance modification of PLA in the case of (reactive) blending PLA-based systems. PMID:24790960

  20. Plasticity theory

    CERN Document Server

    Lubliner, Jacob

    2008-01-01

    The aim of Plasticity Theory is to provide a comprehensive introduction to the contemporary state of knowledge in basic plasticity theory and to its applications. It treats several areas not commonly found between the covers of a single book: the physics of plasticity, constitutive theory, dynamic plasticity, large-deformation plasticity, and numerical methods, in addition to a representative survey of problems treated by classical methods, such as elastic-plastic problems, plane plastic flow, and limit analysis; the problem discussed come from areas of interest to mechanical, structural, and