Elastic modulus and fracture of boron carbide
International Nuclear Information System (INIS)
Hollenberg, G.W.; Walther, G.
1978-12-01
The elastic modulus of hot-pressed boron carbide with 1 to 15% porosity was measured at room temperature. K/sub IC/ values were determined for the same porosity range at 500 0 C by the double torsion technique. The critical stress intensity factor of boron carbide with 8% porosity was evaluated from 25 to 1200 0 C
Thickness dependence of nanofilm elastic modulus
Czech Academy of Sciences Publication Activity Database
Fedorchenko, Alexander I.; Wang, A. B.; Cheng, H.H.
2009-01-01
Roč. 94, č. 15 (2009), s. 152111-152113 ISSN 0003-6951 Institutional research plan: CEZ:AV0Z20760514 Keywords : nanofilm * elastic modulus * thickness dependence Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.554, year: 2009 http://link.aip.org/link/?APPLAB/94/152111/1
Determination of elastic modulus in nickel alloy from ultrasonic ...
Indian Academy of Sciences (India)
als scientists, and solid-state theorists; they connect to tech- nological, structural economics and safety, to various mate- rials phenomena and to their fundamental interatomic forces. (Ledbetter 1983). In any material which is a multiphase alloy, the elastic modulus is determined by the modulus of the indi- vidual phases and ...
Determination of elastic modulus of ceramics using ultrasonic testing
Sasmita, Firmansyah; Wibisono, Gatot; Judawisastra, Hermawan; Priambodo, Toni Agung
2018-04-01
Elastic modulus is important material property on structural ceramics application. However, bending test as a common method for determining this property require particular specimen preparation. Furthermore, elastic modulus of ceramics could vary because it depends on porosity content. For structural ceramics industry, such as ceramic tiles, this property is very important. This drives the development of new method to improve effectivity or verification method as well. In this research, ultrasonic testing was conducted to determine elastic modulus of soda lime glass and ceramic tiles. The experiment parameter was frequency of probe (1, 2, 4 MHz). Characterization of density and porosity were also done for analysis. Results from ultrasonic testing were compared with elastic modulus resulted from bending test. Elastic modulus of soda-lime glass based on ultrasonic testing showed excellent result with error 2.69% for 2 MHz probe relative to bending test result. Testing on red and white ceramic tiles were still contained error up to 41% and 158%, respectively. The results for red ceramic tile showed trend that 1 MHz probe gave better accuracy in determining elastic modulus. However, testing on white ceramic tile showed different trend. It was due to the presence of porosity and near field effect.
Device to measure elastic modulus of superconducting windings
CERN PhotoLab
1979-01-01
This device was made to measure elastic modulus of the Po dipole superconducting coils. More elaborated devices, but based on the same concept, were later used to measure the apparent elastic moduli of the LHC superconducting magnet coils. See also 7903547X, 7901386.
Elastic Modulus at High Frequency of Polymerically Stabilized Suspensions
Nommensen, P.A.; Duits, Michael H.G.; van den Ende, Henricus T.M.; Mellema, J.
2000-01-01
The elastic moduli of polymerically stabilized suspensions consisting of colloidal silica particles coated with endgrafted PDMS (Mn = 80 000) in heptane, were measured as a function of concentration. And the elastic modulus at high frequency G'.. was quantitatively described by model calculations
Effective Elastic Modulus of Structured Adhesives: From Biology to Biomimetics
Directory of Open Access Journals (Sweden)
Xin Wang
2017-06-01
Full Text Available Micro- and nano-hierarchical structures (lamellae, setae, branches, and spatulae on the toe pads of many animals play key roles for generating strong but reversible adhesion for locomotion. The hierarchical structure possesses significantly reduced, effective elastic modulus (Eeff, as compared to the inherent elastic modulus (Einh of the corresponding biological material (and therefore contributes to a better compliance with the counterpart surface. Learning from nature, three types of hierarchical structures (namely self-similar pillar structure, lamella–pillar hybrid structure, and porous structure have been developed and investigated.
Multigene Genetic Programming for Estimation of Elastic Modulus of Concrete
Directory of Open Access Journals (Sweden)
Alireza Mohammadi Bayazidi
2014-01-01
Full Text Available This paper presents a new multigene genetic programming (MGGP approach for estimation of elastic modulus of concrete. The MGGP technique models the elastic modulus behavior by integrating the capabilities of standard genetic programming and classical regression. The main aim is to derive precise relationships between the tangent elastic moduli of normal and high strength concrete and the corresponding compressive strength values. Another important contribution of this study is to develop a generalized prediction model for the elastic moduli of both normal and high strength concrete. Numerous concrete compressive strength test results are obtained from the literature to develop the models. A comprehensive comparative study is conducted to verify the performance of the models. The proposed models perform superior to the existing traditional models, as well as those derived using other powerful soft computing tools.
Elastic modulus of tree frog adhesive toe pads.
Barnes, W Jon P; Goodwyn, Pablo J Perez; Nokhbatolfoghahai, Mohsen; Gorb, Stanislav N
2011-10-01
Previous work using an atomic force microscope in nanoindenter mode indicated that the outer, 10- to 15-μm thick, keratinised layer of tree frog toe pads has a modulus of elasticity equivalent to silicone rubber (5-15 MPa) (Scholz et al. 2009), but gave no information on the physical properties of deeper structures. In this study, micro-indentation is used to measure the stiffness of whole toe pads of the tree frog, Litoria caerulea. We show here that tree frog toe pads are amongst the softest of biological structures (effective elastic modulus 4-25 kPa), and that they exhibit a gradient of stiffness, being stiffest on the outside. This stiffness gradient results from the presence of a dense network of capillaries lying beneath the pad epidermis, which probably has a shock absorbing function. Additionally, we compare the physical properties (elastic modulus, work of adhesion, pull-off force) of the toe pads of immature and adult frogs.
Size effect of the elastic modulus of rectangular nanobeams: Surface elasticity effect
International Nuclear Information System (INIS)
Yao Hai-Yan; Fan Wen-Liang; Yun Guo-Hong
2013-01-01
The size-dependent elastic property of rectangular nanobeams (nanowires or nanoplates) induced by the surface elasticity effect is investigated by using a developed modified core-shell model. The effect of surface elasticity on the elastic modulus of nanobeams can be characterized by two surface related parameters, i.e., inhomogeneous degree constant and surface layer thickness. The analytical results show that the elastic modulus of the rectangular nanobeam exhibits a distinct size effect when its characteristic size reduces below 100 nm. It is also found that the theoretical results calculated by a modified core-shell model have more obvious advantages than those by other models (core-shell model and core-surface model) by comparing them with relevant experimental measurements and computational results, especially when the dimensions of nanostructures reduce to a few tens of nanometers. (condensed matter: structural, mechanical, and thermal properties)
Young's modulus of elasticity of Schlemm's canal endothelial cells.
Zeng, Dehong; Juzkiw, Taras; Read, A Thomas; Chan, Darren W-H; Glucksberg, Matthew R; Ethier, C Ross; Johnson, Mark
2010-02-01
Schlemm's canal (SC) endothelial cells are likely important in the physiology and pathophysiology of the aqueous drainage system of the eye, particularly in glaucoma. The mechanical stiffness of these cells determines, in part, the extent to which they can support a pressure gradient and thus can be used to place limits on the flow resistance that this layer can generate in the eye. However, little is known about the biomechanical properties of SC endothelial cells. Our goal in this study was to estimate the effective Young's modulus of elasticity of normal SC cells. To do so, we combined magnetic pulling cytometry of isolated cultured human SC cells with finite element modeling of the mechanical response of the cell to traction forces applied by adherent beads. Preliminary work showed that the immersion angles of beads attached to the SC cells had a major influence on bead response; therefore, we also measured bead immersion angle by confocal microscopy, using an empirical technique to correct for axial distortion of the confocal images. Our results showed that the upper bound for the effective Young's modulus of elasticity of the cultured SC cells examined in this study, in central, non-nuclear regions, ranged between 1,007 and 3,053 Pa, which is similar to, although somewhat larger than values that have been measured for other endothelial cell types. We compared these values to estimates of the modulus of primate SC cells in vivo, based on images of these cells under pressure loading, and found good agreement at low intraocular pressure (8-15 mm Hg). However, increasing intraocular pressure (22-30 mm Hg) appeared to cause a significant increase in the modulus of these cells. These moduli can be used to estimate the extent to which SC cells deform in response to the pressure drop across the inner wall endothelium and thereby estimate the extent to which they can generate outflow resistance.
Resonant frequency and elastic modulus measurements on hardened cement pastes
International Nuclear Information System (INIS)
Lee, D.J.
1982-12-01
A new technique for measuring resonant frequency and elastic modulus is described. This has been used on specimens of hardened cement paste containing water with no simulated waste, and the results compared with measurements of ultrasonic pulse velocity, dimensional movements and compressive strength made on the same formulations. In addition, measurements were made on a specimen containing simulated waste which demonstrated the applicability of the new technique for following the development of the mechanical properties of cemented simulant radioactive waste in the laboratory. (U.K.)
Nanoscale elastic modulus variation in loaded polymeric micelle reactors.
Solmaz, Alim; Aytun, Taner; Deuschle, Julia K; Ow-Yang, Cleva W
2012-07-17
Tapping mode atomic force microscopy (TM-AFM) enables mapping of chemical composition at the nanoscale by taking advantage of the variation in phase angle shift arising from an embedded second phase. We demonstrate that phase contrast can be attributed to the variation in elastic modulus during the imaging of zinc acetate (ZnAc)-loaded reverse polystyrene-block-poly(2-vinylpyridine) (PS-b-P2VP) diblock co-polymer micelles less than 100 nm in diameter. Three sample configurations were characterized: (i) a 31.6 μm thick polystyrene (PS) support film for eliminating the substrate contribution, (ii) an unfilled PS-b-P2VP micelle supported by the same PS film, and (iii) a ZnAc-loaded PS-b-P2VP micelle supported by the same PS film. Force-indentation (F-I) curves were measured over unloaded micelles on the PS film and over loaded micelles on the PS film, using standard tapping mode probes of three different spring constants, the same cantilevers used for imaging of the samples before and after loading. For calibration of the tip geometry, nanoindentation was performed on the bare PS film. The resulting elastic modulus values extracted by applying the Hertz model were 8.26 ± 3.43 GPa over the loaded micelles and 4.17 ± 1.65 GPa over the unloaded micelles, confirming that phase contrast images of a monolayer of loaded micelles represent maps of the nanoscale chemical and mechanical variation. By calibrating the tip geometry indirectly using a known soft material, we are able to use the same standard tapping mode cantilevers for both imaging and indentation.
Wu, H. I.; Spence, R. D.; Sharpe, P. J.; Goeschl, J. D.
1985-01-01
The traditional bulk elastic modulus approach to plant cell pressure-volume relations is inconsistent with its definition. The relationship between the bulk modulus and Young's modulus that forms the basis of their usual application to cell pressure-volume properties is demonstrated to be physically meaningless. The bulk modulus describes stress/strain relations of solid, homogeneous bodies undergoing small deformations, whereas the plant cell is best described as a thin-shelled, fluid-filled structure with a polymer base. Because cell walls possess a polymer structure, an alternative method of mechanical analysis is presented using polymer elasticity principles. This initial study presents the groundwork of polymer mechanics as would be applied to cell walls and discusses how the matrix and microfibrillar network induce nonlinear stress/strain relationships in the cell wall in response to turgor pressure. In subsequent studies, these concepts will be expanded to include anisotropic expansion as regulated by the microfibrillar network.
Directory of Open Access Journals (Sweden)
Muhammad Ridwan
2017-01-01
Full Text Available Bricks of low elastic modulus are occasionally used in some developing countries, such as Indonesia and India. Most of the previous research efforts focused on masonry structures built with bricks of considerably high elastic modulus. The objective of this study is to quantify the equivalent elastic modulus of lower-stiffness masonry structures, when the mortar has a higher modulus of elasticity than the bricks, by employing finite element (FE simulations and adopting the homogenization technique. The reported numerical simulations adopted the two-dimensional representative volume elements (RVEs using quadrilateral elements with four nodes. The equivalent elastic moduli of composite elements with various bricks and mortar were quantified. The numerically estimated equivalent elastic moduli from the FE simulations were verified using previously established test data. Hence, a new simplified formula for the calculation of the equivalent modulus of elasticity of such masonry structures is proposed in the present study.
Directory of Open Access Journals (Sweden)
Holmes Amey J
2005-07-01
Full Text Available Abstract Background Bronchial hyperreactivity is influenced by properties of the conducting airways and the surrounding pulmonary parenchyma, which is tethered to the conducting airways. Vitamin A deficiency (VAD is associated with an increase in airway hyperreactivity in rats and a decrease in the volume density of alveoli and alveolar ducts. To better define the effects of VAD on the mechanical properties of the pulmonary parenchyma, we have studied the elastic modulus, elastic fibers and elastin gene-expression in rats with VAD, which were supplemented with retinoic acid (RA or remained unsupplemented. Methods Parenchymal mechanics were assessed before and after the administration of carbamylcholine (CCh by determining the bulk and shear moduli of lungs that that had been removed from rats which were vitamin A deficient or received a control diet. Elastin mRNA and insoluble elastin were quantified and elastic fibers were enumerated using morphometric methods. Additional morphometric studies were performed to assess airway contraction and alveolar distortion. Results VAD produced an approximately 2-fold augmentation in the CCh-mediated increase of the bulk modulus and a significant dampening of the increase in shear modulus after CCh, compared to vitamin A sufficient (VAS rats. RA-supplementation for up to 21 days did not reverse the effects of VAD on the elastic modulus. VAD was also associated with a decrease in the concentration of parenchymal elastic fibers, which was restored and was accompanied by an increase in tropoelastin mRNA after 12 days of RA-treatment. Lung elastin, which was resistant to 0.1 N NaOH at 98°, decreased in VAD and was not restored after 21 days of RA-treatment. Conclusion Alterations in parenchymal mechanics and structure contribute to bronchial hyperreactivity in VAD but they are not reversed by RA-treatment, in contrast to the VAD-related alterations in the airways.
Effective elastic modulus of isolated gecko setal arrays.
Autumn, K; Majidi, C; Groff, R E; Dittmore, A; Fearing, R
2006-09-01
Conventional pressure sensitive adhesives (PSAs) are fabricated from soft viscoelastic materials that satisfy Dahlquist's criterion for tack with a Young's modulus (E) of 100 kPa or less at room temperature and 1 Hz. In contrast, the adhesive on the toes of geckos is made of beta-keratin, a stiff material with E at least four orders of magnitude greater than the upper limit of Dahlquist's criterion. Therefore, one would not expect a beta-keratin structure to function as a PSA by deforming readily to make intimate molecular contact with a variety of surface profiles. However, since the gecko adhesive is a microstructure in the form of an array of millions of high aspect ratio shafts (setae), the effective elastic modulus (E(eff)) is much lower than E of bulk beta-keratin. In the first test of the E(eff) of a gecko setal adhesive, we measured the forces resulting from deformation of isolated arrays of tokay gecko (Gekko gecko) setae during vertical compression, and during tangential compression at angles of +45 degrees and -45 degrees . We tested the hypothesis that E(eff) of gecko setae falls within Dahlquist's criterion for tack, and evaluated the validity of a model of setae as cantilever beams. Highly linear forces of deformation under all compression conditions support the cantilever model. E(eff) of setal arrays during vertical and +45 degrees compression (along the natural path of drag of the setae) were 83+/-4.0 kPa and 86+/-4.4 kPa (means +/- s.e.m.), respectively. Consistent with the predictions of the cantilever model, setae became significantly stiffer when compressed against the natural path of drag: E(eff) during -45 degrees compression was 110+/-4.7 kPa. Unlike synthetic PSAs, setal arrays act as Hookean elastic solids; setal arrays function as a bed of springs with a directional stiffness, assisting alignment of the adhesive spatular tips with the contact surface during shear loading.
The effect of elastic modulus on ablation catheter contact area.
Camp, Jon J; Linte, Cristian A; Rettmann, Maryam E; Sun, Deyu; Packer, Douglas L; Robb, Richard A; Holmes, David R
2015-02-21
Cardiac ablation consists of navigating a catheter into the heart and delivering RF energy to electrically isolate tissue regions that generate or propagate arrhythmia. Besides the challenges of accurate and precise targeting of the arrhythmic sites within the beating heart, limited information is currently available to the cardiologist regarding intricate electrode-tissue contact, which directly impacts the quality of produced lesions. Recent advances in ablation catheter design provide intra-procedural estimates of tissue-catheter contact force, but the most direct indicator of lesion quality for any particular energy level and duration is the tissue-catheter contact area, and that is a function of not only force, but catheter pose and material elasticity as well. In this experiment, we have employed real-time ultrasound (US) imaging to determine the complete interaction between the ablation electrode and tissue to accurately estimate contact, which will help to better understand the effect of catheter pose and position relative to the tissue. By simultaneously recording tracked position, force reading and US image of the ablation catheter, the differing material properties of polyvinyl alcohol cryogel [1] phantoms are shown to produce varying amounts of tissue depression and contact area (implying varying lesion quality) for equivalent force readings. We have shown that the elastic modulus significantly affects the surface-contact area between the catheter and tissue at any level of contact force. Thus we provide evidence that a prescribed level of catheter force may not always provide sufficient contact area to produce an effective ablation lesion in the prescribed ablation time.
Low elastic modulus titanium–nickel scaffolds for bone implants
International Nuclear Information System (INIS)
Li, Jing; Yang, Hailin; Wang, Huifeng; Ruan, Jianming
2014-01-01
The superelastic nature of repeating the human bones is crucial to the ideal artificial biomedical implants to ensure smooth load transfer and foster the ingrowth of new bone tissues. Three dimensional interconnected porous TiNi scaffolds, which have the tailorable porous structures with micro-hole, were fabricated by slurry immersing with polymer sponge and sintering method. The crystallinity and phase composition of scaffolds were studied by X-ray diffraction. The pore morphology, size and distribution in the scaffolds were characterized by scanning electron microscopy. The porosity ranged from 65 to 72%, pore size was 250–500 μm. Compressive strength and elastic modulus of the scaffolds were ∼ 73 MPa and ∼ 3GPa respectively. The above pore structural and mechanical properties are similar to those of cancellous bone. In the initial cell culture test, osteoblasts adhered well to the scaffold surface during a short time, and then grew smoothly into the interconnected pore channels. These results indicate that the porous TiNi scaffolds fabricated by this method could be bone substitute materials. - Highlights: • A novel approach for the fabrication of porous TiNi scaffolds • Macroporous structures are replicated from the polymer sponge template. • The pore characteristics and mechanical properties of TiNi scaffolds agree well with the requirement of trabecular bone. • Cytocompatibility of TiNi scaffolds is assessed, and it closely associated with pore property
Reliable measurement of elastic modulus of cells by nanoindentation in an atomic force microscope
Zhou, Zhoulong; Ngan, Alfonso H W; Tang, Bin; Wang, Anxun
2012-01-01
The elastic modulus of an oral cancer cell line UM1 is investigated by nanoindentation in an atomic force microscope with a flat-ended tip. The commonly used Hertzian method gives apparent elastic modulus which increases with the loading rate, indicating strong effects of viscoelasticity. On the contrary, a rate-jump method developed for viscoelastic materials gives elastic modulus values which are independent of the rate-jump magnitude. The results show that the rate-jump method can be used as a standard protocol for measuring elastic stiffness of living cells, since the measured values are intrinsic properties of the cells. © 2011 Elsevier Ltd.
Reliable measurement of elastic modulus of cells by nanoindentation in an atomic force microscope
Zhou, Zhoulong
2012-04-01
The elastic modulus of an oral cancer cell line UM1 is investigated by nanoindentation in an atomic force microscope with a flat-ended tip. The commonly used Hertzian method gives apparent elastic modulus which increases with the loading rate, indicating strong effects of viscoelasticity. On the contrary, a rate-jump method developed for viscoelastic materials gives elastic modulus values which are independent of the rate-jump magnitude. The results show that the rate-jump method can be used as a standard protocol for measuring elastic stiffness of living cells, since the measured values are intrinsic properties of the cells. © 2011 Elsevier Ltd.
The variation in elastic modulus throughout the compression of foam materials
International Nuclear Information System (INIS)
Sun, Yongle; Amirrasouli, B.; Razavi, S.B.; Li, Q.M.; Lowe, T.; Withers, P.J.
2016-01-01
We present a comprehensive experimental study of the variation in apparent unloading elastic modulus of polymer (largely elastic), aluminium (largely plastic) and fibre-reinforced cement (quasi-brittle) closed-cell foams throughout uniaxial compression. The results show a characteristic “zero-yield-stress” response and thereafter a rapid increase in unloading modulus during the supposedly “elastic” regime of the compressive stress–strain curve. The unloading modulus then falls with strain due to the localised cell-wall yielding or failure in the pre-collapse stage and the progressive cell crushing in the plateau stage, before rising sharply during the densification stage which is associated with global cell crushing and foam compaction. A finite element model based on the actual 3D cell structure of the aluminium foam imaged by X-ray computed tomography (CT) predicts an approximately linear fall of elastic modulus from zero strain until a band of collapsed cells forms. It shows that the subsequent gradual decrease in modulus is caused by the progressive collapse of cells. The elastic modulus rises sharply after the densification initiation strain has been reached. However, the elastic modulus is still well below that of the constituent material even when the “fully” dense state is approached. This work highlights the fact that the unloading elastic modulus varies throughout compression and challenges the idea that a constant elastic modulus can be applied in a homogenised foam model. It is suggested that the most representative value of elastic modulus may be obtained by extrapolating the measured unloading modulus to zero strain.
Change and anisotropy of elastic modulus in sheet metals due to plastic deformation
Ishitsuka, Yuki; Arikawa, Shuichi; Yoneyama, Satoru
2015-03-01
In this study, the effect of the plastic deformation on the microscopic structure and the anisotropy of the elastic modulus in the cold-rolled steel sheet (SPCC) is investigated. Various uniaxial plastic strains (0%, 2.5%, 5%, 7.5%, and 10%) are applied to the annealed SPCC plates, then, the specimens for the tensile tests are cut out from them. The elastic moduli in the longitudinal direction and the transverse direction to the direction that are pre-strained are measured by the tensile tests. Cyclic tests are performed to investigate the effects of the internal friction caused by the movable dislocations in the elastic deformation. Also, the movable dislocations are quantified by the boundary tracking for TEM micrographs. In addition, the behaviors of the change of the elastic modulus in the solutionized and thermal aged aluminum alloy (A5052) are measured to investigate the effect on the movable dislocations with the amount of the depositions. As a result in SPCC, the elastic moduli of the 0° and 90° directions decrease more than 10% as 10% prestrain applied. On the other hand, the elastic modulus shows the recovery behavior after the strain aging and the annealing. The movable dislocation and the internal friction show a tendency to increase as the plastic strain increases. The marked anisotropy is not observed in the elastic modulus and the internal friction. The elastic modulus in A5052 with many and few depositions decreases similarly by the plastic deformation. From the above, the movable dislocations affect the elastic modulus strongly without depending on the deposition amount. Moreover, the elastic modulus recovers after the plastic deformation by reducing the effects of them with the strain aging and the heat treatment.
Directory of Open Access Journals (Sweden)
Brian Chin Wing Kot
Full Text Available Standardization on Shear wave ultrasound elastography (SWUE technical settings will not only ensure that the results are accurate, but also detect any differences over time that may be attributed to true physiological changes. The present study evaluated the variations of elastic modulus of muscle and tendon using SWUE when different technical aspects were altered. The results of this study indicated that variations of elastic modulus of muscle and tendon were found when different transducer's pressure and region of interest (ROI's size were applied. No significant differences in elastic modulus of the rectus femoris muscle and patellar tendon were found with different acquisition times of the SWUE sonogram. The SWUE on the muscle and tendon should be performed with the lightest transducer's pressure, a shorter acquisition time for the SWUE sonogram, while measuring the mean elastic modulus regardless the ROI's size.
Elastic Metamaterials with Simultaneously Negative Effective Shear Modulus and Mass Density
Wu, Ying; Lai, Yun; Zhang, Zhao-Qing
2011-01-01
We propose a type of elastic metamaterial comprising fluid-solid composite inclusions which can possess a negative shear modulus and negative mass density over a large frequency region. Such a material has the unique property that only transverse
Hardness and Elastic Modulus of Titanium Nitride Coatings Prepared by Pirac Method
Wu, Siyuan; Wu, Shoujun; Zhang, Guoyun; Zhang, Weiguo
In the present work, hardness and elastic modulus of a titanium nitride coatings prepared on Ti6Al4V by powder immersion reaction-assisted coating (PIRAC) are tested and comparatively studied with a physical vapor deposition (PVD) TiN coating. Surface hardness of the PIRAC coatings is about 11GPa, much lower than that of PVD coating of 22GPa. The hardness distribution profile from surface to substrate of the PVD coatings is steeply decreased from ˜22GPa to ˜4.5GPa of the Ti6Al4V substrate. The PIRAC coatings show a gradually decreasing hardness distribution profile. Elastic modulus of the PVD coating is about 426GPa. The PIRAC coatings show adjustable elastic modulus. Elastic modulus of the PIRAC coatings prepared at 750∘C for 24h and that at 800∘C for 8h is about 234 and 293GPa, respectively.
The dimensional stability and elastic modulus of cemented simulant Winfrith reactor (SGHWR) sludge
International Nuclear Information System (INIS)
Holland, T.R.; Lee, D.J.
1985-12-01
Dimensional changes and elastic modulus have been monitored on cemented simulant sludge stored in various environments. Specimens prepared using a blended cement show no serious detrimental effects during sealed storage, underwater storage or freeze/thaw cycling. (author)
Shear elastic modulus of magnetic gels with random distribution of magnetizable particles
Iskakova, L. Yu; Zubarev, A. Yu
2017-04-01
Magnetic gels present new type of composite materials with rich set of uniquie physical properties, which find active applications in many industrial and bio-medical technologies. We present results of mathematically strict theoretical study of elastic modulus of these systems with randomly distributed magnetizable particles in an elastic medium. The results show that an external magnetic field can pronouncedly increase the shear modulus of these composites.
Modular correction method of bending elastic modulus based on sliding behavior of contact point
International Nuclear Information System (INIS)
Ma, Zhichao; Zhao, Hongwei; Zhang, Qixun; Liu, Changyi
2015-01-01
During the three-point bending test, the sliding behavior of the contact point between the specimen and supports was observed, the sliding behavior was verified to affect the measurements of both deflection and span length, which directly affect the calculation of the bending elastic modulus. Based on the Hertz formula to calculate the elastic contact deformation and the theoretical calculation of the sliding behavior of the contact point, a theoretical model to precisely describe the deflection and span length as a function of bending load was established. Moreover, a modular correction method of bending elastic modulus was proposed, via the comparison between the corrected elastic modulus of three materials (H63 copper–zinc alloy, AZ31B magnesium alloy and 2026 aluminum alloy) and the standard modulus obtained from standard uniaxial tensile tests, the universal feasibility of the proposed correction method was verified. Also, the ratio of corrected to raw elastic modulus presented a monotonically decreasing tendency as the raw elastic modulus of materials increased. (technical note)
Developing the elastic modulus measurement of asphalt concrete using the compressive strength test
Setiawan, Arief; Suparma, Latif Budi; Mulyono, Agus Taufik
2017-11-01
Elastic modulus is a fundamental property of an asphalt mixture. An analytical method of the elastic modulus is needed to determine the thickness of flexible pavement. It has a role as one of the input values on a stress-strain analysis in the finite element method. The aim of this study was to develop the measurement of the elastic modulus by using compressive strength testing. This research used a set of specimen mold tool and Delta Dimensi software to record strain changes occurring in the proving ring of compression machine and the specimens. The elastic modulus of the five types of aggregate gradation and 2 types of asphalt were measured at optimum asphalt content. Asphalt Cement 60/70 and Elastomer Modified Asphalt (EMA) were used as a binder. Manufacturing success indicators of the specimens used void-in-the-mix (VIM) 3-5 % criteria. The success rate of the specimen manufacturing was more than 76%. Thus, the procedure and the compressive strength test equipment could be used for the measurement of the elastic modulus. The aggregate gradation and asphalt types significantly affected the elastic modulus of the asphalt concrete.
Ultrasound estimation and FE analysis of elastic modulus of Kelvin foam
Energy Technology Data Exchange (ETDEWEB)
Kim, Nohyu; Yang, Seung Yong [School of Mechatronics Engineering, Korea University of Technology and Education, Cheonan (Korea, Republic of)
2016-02-15
The elastic modulus of a 3D-printed Kelvin foam plate is investigated by measuring the acoustic wave velocity of 1 MHz ultrasound. An isotropic tetrakaidecahedron foam with 3 mm unit cell is designed and printed layer upon layer to fabricate a Kelvin foam plate of 14 mm thickness with a 3D CAD/printer using ABS plastic. The Kelvin foam plate is completely filled with paraffin wax for impedance matching, so that the acoustic wave may propagate through the porous foam plate. The acoustic wave velocity of the foam plate is measured using the time-of-flight (TOF) method and is used to calculate the elastic modulus of the Kelvin foam plate based on acousto-elasticity. Finite element method (FEM) and micromechanics is applied to the Kelvin foam plate to calculate the theoretical elastic modulus using a non-isotropic tetrakaidecahedron model. The predicted elastic modulus of the Kelvin foam plate from FEM and micromechanics model is similar, which is only 3-4% of the bulk material. The experimental value of the elastic modulus from the ultrasonic method is approximately twice as that of the numerical and theoretical methods because of the flexural deformation of the cell edges neglected in the ultrasonic method.
Ultrasound estimation and FE analysis of elastic modulus of Kelvin foam
International Nuclear Information System (INIS)
Kim, Nohyu; Yang, Seung Yong
2016-01-01
The elastic modulus of a 3D-printed Kelvin foam plate is investigated by measuring the acoustic wave velocity of 1 MHz ultrasound. An isotropic tetrakaidecahedron foam with 3 mm unit cell is designed and printed layer upon layer to fabricate a Kelvin foam plate of 14 mm thickness with a 3D CAD/printer using ABS plastic. The Kelvin foam plate is completely filled with paraffin wax for impedance matching, so that the acoustic wave may propagate through the porous foam plate. The acoustic wave velocity of the foam plate is measured using the time-of-flight (TOF) method and is used to calculate the elastic modulus of the Kelvin foam plate based on acousto-elasticity. Finite element method (FEM) and micromechanics is applied to the Kelvin foam plate to calculate the theoretical elastic modulus using a non-isotropic tetrakaidecahedron model. The predicted elastic modulus of the Kelvin foam plate from FEM and micromechanics model is similar, which is only 3-4% of the bulk material. The experimental value of the elastic modulus from the ultrasonic method is approximately twice as that of the numerical and theoretical methods because of the flexural deformation of the cell edges neglected in the ultrasonic method
Pepi, John W.
2017-08-01
Thermally induced stress is readily calculated for linear elastic material properties using Hooke's law in which, for situations where expansion is constrained, stress is proportional to the product of the material elastic modulus and its thermal strain. When material behavior is nonlinear, one needs to make use of nonlinear theory. However, we can avoid that complexity in some situations. For situations in which both elastic modulus and coefficient of thermal expansion vary with temperature, solutions can be formulated using secant properties. A theoretical approach is thus presented to calculate stresses for nonlinear, neo-Hookean, materials. This is important for high acuity optical systems undergoing large temperature extremes.
The elastic modulus of alumina-zirconia composite using through transmission ultrasonics
International Nuclear Information System (INIS)
Tan, K.S.; Hing, P.
1996-01-01
The elastic modulus of unstabilized Al 2 O 3 -ZrO 2 composites is determined from ultrasonic velocities and density measurements. The dynamic elastic modulus and the density of the green unstabilized Al 2 O 3 -ZrO 2 follow the rule of mixture. However, the elastic modulus and density of the sintered Al 2 O 3 -ZrO 2 do not follow the rule of mixture. The elastic modulus and diametrical compressive fracture stress of the Al 2 O 3 can be enhanced by (1) a high green (before sintering) compacting pressure and (2) addition of about 3wt% unstabilized ZrO 2 at a sintering time of two hours at 1550 degC. The ZrO 2 is found to improve the bulk density of the composite by a reduction in the porosity. This improves the elastic modulus and the diametrical compressive fracture stress. The thermal expansion on cooling with > 25wt% ZrO 2 in the Al 2 O 3 matrix has also been established. (author)
Size dependent elastic modulus and mechanical resilience of dental enamel.
O'Brien, Simona; Shaw, Jeremy; Zhao, Xiaoli; Abbott, Paul V; Munroe, Paul; Xu, Jiang; Habibi, Daryoush; Xie, Zonghan
2014-03-21
Human tooth enamel exhibits a unique microstructure able to sustain repeated mechanical loading during dental function. Although notable advances have been made towards understanding the mechanical characteristics of enamel, challenges remain in the testing and interpretation of its mechanical properties. For example, enamel was often tested under dry conditions, significantly different from its native environment. In addition, constant load, rather than indentation depth, has been used when mapping the mechanical properties of enamel. In this work, tooth specimens are prepared under hydrated conditions and their stiffnesses are measured by depth control across the thickness of enamel. Crystal arrangement is postulated, among other factors, to be responsible for the size dependent indentation modulus of enamel. Supported by a simple structure model, effective crystal orientation angle is calculated and found to facilitate shear sliding in enamel under mechanical contact. In doing so, the stress build-up is eased and structural integrity is maintained. Copyright © 2014 Elsevier Ltd. All rights reserved.
The Effect of Annealing on the Elastic Modulus of Orthodontic Wires
Higginbottom, Kyle
Introduction: Nickel Titanium orthodontic wires are currently used in orthodontic treatment due to their heat activated properties and their delivery of constant force. The objective of this study was to determine the effect of annealing on the elastic modulus of Nickel Titanium, Stainless Steel and Beta-titanium (TMA) wires. Different points along the wire were tested in order to determine how far from the annealed ends the elastic modulus of the wires was affected. Methods: Eighty (80) orthodontic wires consisting of 4 equal groups (SS/TMA/Classic NitinolRTM/Super Elastic NitinolRTM) were used as the specimens for this study. All wires were measured and marked at 5mm measurements, and cut into 33.00mm sections. The wires were heated with a butane torch until the first 13.00mm of the wires were red hot. Load deflection tests using an InstronRTM universal testing machine were run at 5mm distances from the end of the wire that had been annealed. The change in elastic modulus was then determined. Results: There was a significant difference (F = 533.001, p = 0.0005) in the change in elastic modulus for the four distances. There was also a significant difference (F = 57.571, p = 0.0005) in the change in elastic modulus for the four wire types. There was a significant interaction (F = 19.601, p = 0.005) between wire type and distance, however this interaction negated the differences between the wires. Conclusion: 1) There are significant differences in the changes in elastic modulus between the areas of the wires within the annealed section and those areas 5mm and 10mm away from the annealed section. The change in elastic modulus within the annealed section was significantly greater at 8 mm than it was at 13mm, and this was significantly greater than 18mm and 23mm (5mm and 10mm beyond the annealed section). However, there was no statistical difference in the change in elastic modulus between 5mm and 10mm away from the annealed section (18mm and 23mm respectively). 2
Consequence of reduced necrotic bone elastic modulus in a Perthes' hip
DEFF Research Database (Denmark)
Salmingo, Remel A.; Skytte, Tina Lercke; Mikkelsen, Lars Pilgaard
Introduction Perthes is a destructive hip joint disorder characterized as a malformation of the femoral head which affects young children. Several studies have shown the change of mechanical properties of the femoral head in Perthes’ disease. However, the consequence of the changes in bone...... mechanical properties in a Perthes’ hip is not well established. Due to the material differences, changes in bone mechanical properties might lead to localization of stress and deformation. Thus, the objective of this study was to investigate the effects of reduced elastic modulus of necrotic bone...... weight) was applied on the top of the femoral head. The distal part of the femur was fixed. The same Poisson’s ratio 0.3 was set for the femoral and necrotic bone. The elastic modulus (E) of femoral bone was 500 MPa. To investigate the effects of reduced elastic modulus, the necrotic bone E was reduced...
Mechanical properties of concrete with SAP. Part II: Modulus of elasticity
DEFF Research Database (Denmark)
Hasholt, Marianne Tange; Jespersen, Morten H. Seneka; Jensen, Ole Mejlhede
2010-01-01
In this study, focus is on the modulus of elasticity for concrete with superabsorbent polymers (SAP). The results show that based on composite theory it is possible to establish a model, which predicts overall concrete elasticity. The model assumes a three phase material of aggregate, cement paste......, and air with volume fractions of the three phases as well as elastic properties of paste and aggregates as input parameters. Addition of SAP changes the E-modulus, because it both has an influence on properties of the cement paste and on the volume of air voids. Here, the E-modulus is an example...... a more or less empirical relation. The results show that when introducing SAP, models of a more empirical nature can be misleading (and e.g. relations stated in codes are often of this empirical nature). The reason is twofold: First, the empirical models often have a general problem with the effect...
International Nuclear Information System (INIS)
Meza, J. M.; Franco, E. E.; Farias, M. C. M.; Buiochi, F.; Souza, R. M.; Cruz, J.
2008-01-01
Currently, the acoustic and nano indentation techniques are two of the most used techniques for materials elastic modulus measurement. In this article fundamental principles and limitations of both techniques are shown and discussed. Last advances in nano indentation technique are also reviewed. an experimental study in ceramic, metallic, composite and single crystals was also done. Results shown that ultrasonic technique is capable to provide results in agreement with those reported in literature. However, ultrasonic technique does not allow measuring the elastic modulus of some small samples and single crystals. On the other hand, the nano indentation technique estimates the elastic modulus values in reasonable agreement with those measured by acoustic methods, particularly in amorphous materials, while in some policristaline materials some deviation from expected values was obtained. (Author) 29 refs
International Nuclear Information System (INIS)
Oliveira, M.R.; Garcia, G.C.R.; Claudinei, S.; Ribeiro, S.
2011-01-01
The studied castable contain andalusite aggregates, and when sintered in temperatures above 1280 deg C, transformed into mullite improving the properties of concrete due to its low expansion and thermal conductivity, creep resistance and thermal shock. The refractory was homogenized in a mixer with 5.5% m/m of water and poured into a metal mold resulting in prismatic bars. After curing for 48 hours, were sintered at 1450 ° C for 0 h, 1 h, 2.5 h and 10 h with heating and cooling rates of 2 ° C / min. The results of elastic modules were, respectively, in GPa: 25.75±1.75, 37.79±0.36, 39.03±1.97 and 54.47±4.01, and rupture, MPa: 8.40±0.78, 11.94±0.68, 10.91±0.91 and 11,34±1.16, showing the increase in elastic modulus for longer times and for times exceeding one hour, no significant changes in results of the modulus of rupture , stabilizing the change of this refractory's properties after the first hour of sintering. (author)
Elastic Modulus Measurement of ORNL ATF FeCrAl Alloys
Energy Technology Data Exchange (ETDEWEB)
Thompson, Zachary T. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Terrani, Kurt A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Yamamoto, Yukinori [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
2015-10-01
Elastic modulus and Poisson’s ratio for a number of wrought FeCrAl alloys, intended for accident tolerant fuel cladding application, are determined via resonant ultrasonic spectroscopy. The results are reported as a function of temperature from room temperature to 850°C. The wrought alloys were in the fully annealed and unirradiated state. The elastic modulus for the wrought FeCrAl alloys is at least twice that of Zr-based alloys over the temperature range of this study. The Poisson’s ratio of the alloys was 0.28 on average and increased very slightly with increasing temperature.
Modelling of the Elasticity Modulus for Rock Using Genetic Expression Programming
Directory of Open Access Journals (Sweden)
Umit Atici
2016-01-01
Full Text Available In rock engineering projects, statically determined parameters are more reflective of actual load conditions than dynamic parameters. This study reports a new and efficient approach to the formulation of the static modulus of elasticity Es applying gene expression programming (GEP with nondestructive testing (NDT methods. The results obtained using GEP are compared with the results of multivariable linear regression analysis (MRA, univariate nonlinear regression analysis (URA, and the dynamic elasticity modulus (Ed. The GEP model was found to produce the most accurate calculation of Es. The proposed approach is a simple, nondestructive, and practical way to determine Es for anisotropic and heterogeneous rocks.
A summary of modulus of elasticity and knot size surveys for laminating grades of lumber
R. W. Wolfe; R. C. Moody
1981-01-01
A summary of modulus of elasticity (MOE) and knot data is presented for grades of lumber commonly used to manufacture glued-laminated (glulam) timber by the laminating Industry. Tabulated values represent 30 different studies covering a time span of over 16 years. Statistical estimates of average and near-maximum knot sizes as well as mean and coefficient of variation...
Diameter effect on stress-wave evaluation of modulus of elasticity of logs
Xiping Wang; Robert J. Ross; Brian K. Brashaw; John Punches; John R. Erickson; John W. Forsman; Roy E. Pellerin
2004-01-01
Recent studies on nondestructive evaluation (NDE) of logs have shown that a longitudinal stress-wave method can be used to nondestructively evaluate the modulus of elasticity (MOE) of logs. A strong relationship has been found between stress-wave MOE and static MOE of logs, but a significant deviation was observed between stress-wave and static values. The objective of...
MODULUS OF ELASTICITY AND HARDNESS OF COMPRESSION AND OPPOSITE WOOD CELL WALLS OF MASSON PINE
Directory of Open Access Journals (Sweden)
Yanhui Huang,
2012-05-01
Full Text Available Compression wood is commonly found in Masson pine. To evaluate the mechanical properties of the cell wall of Masson pine compression and opposite wood, nanoindentation was used. The results showed that the average values of hardness and cell wall modulus of elasticity of opposite wood were slightly higher than those of compression wood. With increasing age of the annual ring, the modulus of elasticity showed a negative correlation with microfibril angle, but a weak correlation was observed for hardness. In opposite and compression wood from the same annual ring, the differences in average values of modulus of elasticity and hardness were small. These slight differences were explained by the change of microfibril angle (MFA, the press-in mode of nanoindentation, and the special structure of compression wood. The mechanical properties were almost the same for early, transition, and late wood in a mature annual ring of opposite wood. It can therefore be inferred that the average modulus of elasticity (MOE and hardness of the cell walls in a mature annual ring were not being affected by cell wall thickness.
Use of an ultrasonic device for the determination of elastic modulus of dentin.
Miyazaki, Masashi; Inage, Hirohiko; Onose, Hideo
2002-03-01
The mechanical properties of dentin substrate are one of the important factors in determining bond strength of dentin bonding systems. The purpose of this study was to determine the elastic modulus of dentin substrate with the use of an ultrasonic device. The dentin disks of about 1 mm thickness were obtaining from freshly extracted human third molars, and the dentin disk was shaped in a rectangular form with a line diamond point. The size and weight of each specimen was measured to calculate the density of the specimen. The ultrasonic equipment employed in this study was composed of a Pulser-Receiver (Model 5900PR, Panametrics), transducers (V155, V156, Panametrics) and an oscilloscope. The measured two-way transit time through the dentin disk was divided by two to account for the down-and-back travel path, and then multiplied by the velocity of sound in the test material. Measuring the longitudinal and share wave sound velocity determine elastic modulus. The mean elastic modulus of horizontally sectioned specimens was 21.8 GPa and 18.5 GPa for the vertically sectioned specimens, and a significant difference was found between the two groups. The ultrasonic method used in this study shows considerable promise for determination of the elastic modulus of the tooth substrate.
Xiawa Wu; Robert J. Moon; Ashlie Martini
2013-01-01
The elastic modulus of cellulose IÃ in the axial and transverse directions was obtained from atomistic simulations using both the standard uniform deformation approach and a complementary approach based on nanoscale indentation. This allowed comparisons between the methods and closer connectivity to experimental measurement techniques. A reactive...
Evaluating elastic modulus and strength of hard coatings by relative method
International Nuclear Information System (INIS)
Bao, Y.W.; Zhou, Y.C.; Bu, X.X.; Qiu, Y.
2007-01-01
A simple approach named relative method is developed for determining the elastic modulus and strength of hard coatings. Analytical relationship among the moduli of the film, the substrate, and the film/substrate system was derived based on bending model, from which the elastic modulus of the coating can be determined uniquely via the measured moduli of the samples before and after coating. Furthermore, the relationship between the strength of the films and the bending strength of the coated sample is derived, thus both the modulus and the strength of coating can be evaluated via traditional tests on coated samples. Mathematic expressions of those calculations were derived, respectively for rectangular beam samples with three types of coating configurations: single face coating, sandwich coating and around coating. Experimental results using various brittle coatings demonstrated the validity and convenience of this method
Evaluating elastic modulus and strength of hard coatings by relative method
Energy Technology Data Exchange (ETDEWEB)
Bao, Y.W. [Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016 (China); China Building Materials Academy, Beijing 100024 (China)], E-mail: ywbao@imr.ac.cn; Zhou, Y.C. [Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016 (China); Bu, X.X. [China Building Materials Academy, Beijing 100024 (China); Qiu, Y. [China Building Materials Academy, Beijing 100024 (China)
2007-06-15
A simple approach named relative method is developed for determining the elastic modulus and strength of hard coatings. Analytical relationship among the moduli of the film, the substrate, and the film/substrate system was derived based on bending model, from which the elastic modulus of the coating can be determined uniquely via the measured moduli of the samples before and after coating. Furthermore, the relationship between the strength of the films and the bending strength of the coated sample is derived, thus both the modulus and the strength of coating can be evaluated via traditional tests on coated samples. Mathematic expressions of those calculations were derived, respectively for rectangular beam samples with three types of coating configurations: single face coating, sandwich coating and around coating. Experimental results using various brittle coatings demonstrated the validity and convenience of this method.
Xia, Minggang; Liang, Chunping; Hu, Ruixue; Cheng, Zhaofang; Liu, Shiru; Zhang, Shengli
2018-05-01
It is imperative and highly desirable to buffer the stress in flexible electronic devices. In this study, we designed and fabricated lamellate poly(dimethylsiloxane) (PDMS) samples with gradient elastic moduli, motivated by the protection of the pomelo pulp by its skin, followed by the measurements of their elastic moduli. We demonstrated that the electrical and fatigue performances of a Ag-nanowire thin film device on the PDMS substrate with a gradient elastic modulus are significantly better than those of a device on a substrate with a monolayer PDMS. This study provides a robust scheme to effectively protect flexible electronic devices.
Determination of elastic modulus for hollow spherical shells via resonant ultrasound spectroscopy
Energy Technology Data Exchange (ETDEWEB)
Ma, Xiaojun [Institute of Modern Physics, Fudan University, Shanghai 200433 (China); Research Center of Laser Fusion, CAEP, Mianyang 621900 (China); Tang, Xing; Wang, Zongwei [Research Center of Laser Fusion, CAEP, Mianyang 621900 (China); Chen, Qian; Qian, Menglu [Institute of Acoustic, Tongji University, Shanghai 200092 (China); Meng, Jie [Research Center of Laser Fusion, CAEP, Mianyang 621900 (China); Tang, Yongjian [Institute of Modern Physics, Fudan University, Shanghai 200433 (China); Research Center of Laser Fusion, CAEP, Mianyang 621900 (China); Shen, Hao [Institute of Modern Physics, Fudan University, Shanghai 200433 (China); Gao, Dangzhong, E-mail: dgaocn@163.com [Research Center of Laser Fusion, CAEP, Mianyang 621900 (China)
2017-04-15
Highlights: • The axisymmetric frequency equation of an isotropic hollow two-layer sphere is deduced by three dimension elasticity theory and global matrix method. • The simulated results demonstrate that the natural frequencies of a hollow sphere are more strongly dependent on Young’s modulus than Poisson's ratio. • The Young’s moduli of polymer capsules with an sub-millimeter inner radius are measured accurately with an uncertainty of ∼10%. - Abstract: The elastic property of a capsule is one of the essential parameters both in engineering applications and scientific understanding of material nature in inertial confinement fusion (ICF) experiments. The axisymmetric frequency equation of an isotropic hollow two-layer sphere is deduced by three dimension elasticity theory and global matrix method, and a combined resonant ultrasound spectroscopy(RUS), which consists of a piezoelectric-based resonant ultrasound spectroscopy(PZT-RUS) and a laser-based resonant ultrasound spectroscopy(LRUS), is developed for determining the elastic modulus of capsule. To understand the behavior of natural frequencies varying with elastic properties, the dependence of natural frequencies on Young’s modulus and Poisson’s ratio are calculated numerically. Some representative polymer capsules are measured using PZT-RUS and LRUS. Based on the theoretical and experimental results, the Young’s moduli of these capsules are measured accurately with an uncertainty of ∼10%.
Elastic modulus, thermal expansion, and specific heat at a phase transition
International Nuclear Information System (INIS)
Testardi, L.R.
1975-01-01
The interrelation of the elastic modulus, thermal-expansion coefficient, and specific heat of a transformed phase relative to the untransformed phase is calculated assuming a particular but useful form of the thermodynamic potential. For second-order phase transitions where this potential applies, measurements of modulus, expansion, and specific heat can yield the general (longitudinal as well as shear) first- and second-order stress (or strain) dependences of the transition temperature and of the order parameter at absolute zero. An exemplary application to one type of phase transition is given
Enhancement and prediction of modulus of elasticity of palm kernel shell concrete
International Nuclear Information System (INIS)
Alengaram, U. Johnson; Mahmud, Hilmi; Jumaat, Mohd Zamin
2011-01-01
Research highlights: → Micro-pores of size 16-24 μm were found on the outer surface of palm kernel shell. → Infilling of pores by mineral admixtures was evident. → Sand content influenced both modulus of elasticity and compressive strength. → Proposed equation predicts modulus of elasticity within ±1.5 kN/mm 2 of test results. -- Abstract: This paper presents results of an investigation conducted to enhance and predict the modulus of elasticity (MOE) of palm kernel shell concrete (PKSC). Scanning electron microscopic (SEM) analysis on palm kernel shell (PKS) was conducted. Further, the effect of varying sand and PKS contents and mineral admixtures (silica fume and fly ash) on compressive strength and MOE was investigated. The variables include water-to-binder (w/b) and sand-to-cement (s/c) ratios. Nine concrete mixes were prepared, and tests on static and dynamic moduli of elasticity and compressive strength were conducted. The SEM result showed presence of large number of micro-pores on PKS. The mineral admixtures uniformly filled the micro-pores on the outer surface of PKS. Further, the increase in sand content coupled with reduction in PKS content enhanced the compressive strength and static MOE: The highest MOE recorded in this investigation, 11 kN/mm 2 , was twice that previously published. Moreover, the proposed equation based on CEB/FIP code formula appears to predict the MOE close to the experimental values.
Flexural strength and modulus of elasticity of different types of resin-based composites.
Rodrigues Junior, Sinval Adalberto; Zanchi, Cesar Henrique; Carvalho, Rodrigo Varella de; Demarco, Flávio Fernando
2007-01-01
The aim of the study was to test whether the filler composition of resin composites influences their flexural strength and modulus of elasticity. Flexural strength and modulus of elasticity were obtained through a three-point bending test. Twelve bar shaped specimens of 5 commercially available composites--Supreme (3M/ESPE), a universal nanofilled composite; Esthet-X (Dentsply), Z-250 (3M/ESPE), Charisma (Heraeus Kulzer), universal hybrid composites; and Helio Fill (Vigodent), a microfine composite--were confectioned according to the ISO 4049/2000 specifications. The test was performed after a 7-days storage time using a universal test machine with a crosshead speed of 1 mm/min. The filler weight content was determined by the ashing technique. The data obtained on the mechanical properties were submitted to ANOVA and Tukey test (p elasticity results were observed among the universal hybrid composites. The nanofilled composite presented intermediary results. Within the limitations of this in vitro study, it could be concluded that the filler content significantly interfered in the flexural strength and modulus of elasticity of the composites tested.
International Nuclear Information System (INIS)
You, J.H.; Hoeschen, T.; Lindig, S.
2006-01-01
Plasma-sprayed tungsten, which is a candidate material for the first wall armour, shows a porous, heterogeneous microstructure. Due to its characteristic morphology, the properties are significantly different from those of its dense bulk material. Measurements of the elastic modulus of this coating have not been reported in the literature. In this work Young's modulus of highly porous plasma-sprayed tungsten coatings deposited on steel (F82H) substrates was measured. For the fabrication of the coating system the vacuum plasma-spray process was applied. Measurements were performed by means of three-point and four-point bending tests. The obtained modulus values ranged from 53 to 57 GPa. These values could be confirmed by the test result of a detached coating strip, which was 54 GPa. The applied methods produced consistent results regardless of testing configurations and specimen sizes. The errors were less than 1%. Residual stress of the coating was also estimated
You, J. H.; Höschen, T.; Lindig, S.
2006-01-01
Plasma-sprayed tungsten, which is a candidate material for the first wall armour, shows a porous, heterogeneous microstructure. Due to its characteristic morphology, the properties are significantly different from those of its dense bulk material. Measurements of the elastic modulus of this coating have not been reported in the literature. In this work Young's modulus of highly porous plasma-sprayed tungsten coatings deposited on steel (F82H) substrates was measured. For the fabrication of the coating system the vacuum plasma-spray process was applied. Measurements were performed by means of three-point and four-point bending tests. The obtained modulus values ranged from 53 to 57 GPa. These values could be confirmed by the test result of a detached coating strip, which was 54 GPa. The applied methods produced consistent results regardless of testing configurations and specimen sizes. The errors were less than 1%. Residual stress of the coating was also estimated.
Directory of Open Access Journals (Sweden)
Chris L. de Korte
2013-03-01
Full Text Available Atherosclerotic plaque rupture can initiate stroke or myocardial infarction. Lipid-rich plaques with thin fibrous caps have a higher risk to rupture than fibrotic plaques. Elastic moduli differ for lipid-rich and fibrous tissue and can be reconstructed using tissue displacements estimated from intravascular ultrasound radiofrequency (RF data acquisitions. This study investigated if modulus reconstruction is possible for noninvasive RF acquisitions of vessels in transverse imaging planes using an iterative 2D cross-correlation based displacement estimation algorithm. Furthermore, since it is known that displacements can be improved by compounding of displacements estimated at various beam steering angles, we compared the performance of the modulus reconstruction with and without compounding. For the comparison, simulated and experimental RF data were generated of various vessel-mimicking phantoms. Reconstruction errors were less than 10%, which seems adequate for distinguishing lipid-rich from fibrous tissue. Compounding outperformed single-angle reconstruction: the interquartile range of the reconstructed moduli for the various homogeneous phantom layers was approximately two times smaller. Additionally, the estimated lateral displacements were a factor of 2–3 better matched to the displacements corresponding to the reconstructed modulus distribution. Thus, noninvasive elastic modulus reconstruction is possible for transverse vessel cross sections using this cross-correlation method and is more accurate with compounding.
Antony Finto; Lewis Jordan; Laurence R. Schimleck; Alexander Clark; Ray A. Souter; Richard F. Daniels
2011-01-01
Modulus of elasticity (MOE), modulus of rupture (MOR), and specific gravity (SG) are important properties for determining the end-use and value of a piece of lumber. This study addressed the variation in MOE, MOR, and SG with physiographic region, tree height, and wood type. Properties were measured from two static bending samples (dimensions 25.4 mm Ã 25.4 mm Ã 406.4...
Haryanto, Y.; Hermanto, N. I. S.; Pamudji, G.; Wardana, K. P.
2017-11-01
One feasible solution to overcome the issue of tire disposal waste is the use of waste tire rubber to replace aggregate in concrete. We have conducted an experimental investigation on the effect of rubber tire waste aggregate in cuboid form on the compressive strength and modulus of elasticity of concrete. The test was performed on 72 cylindrical specimens with the height of 300 mm and diameter of 150 mm. We found that the workability of concrete with waste tire rubber aggregate has increased. The concrete density with waste tire rubber aggregate was decreased, and so was the compressive strength. The decrease of compressive strength is up to 64.34%. If the content of waste tire rubber aggregate is more than 40%, then the resulting concrete cannot be categorized as structural concrete. The modulus of elasticity decreased to 59.77%. The theoretical equation developed to determine the modulus of elasticity of concrete with rubber tire waste aggregate has an accuracy of 84.27%.
Directory of Open Access Journals (Sweden)
Gabriela Queiroz de Melo Monteiro
2010-03-01
Full Text Available Linear polymerization shrinkage (LPS, flexural strength (FS and modulus of elasticity (ME of 7 dental composites (Filtek Z350™, Filtek Z250™/3M ESPE; Grandio™, Polofil Supra™/VOCO; TPH Spectrum™, TPH3™, Esthet-X™/Denstply were measured. For the measurement of LPS, composites were applied to a cylindrical metallic mold and polymerized (n = 8. The gap formed at the resin/mold interface was observed using scanning electron microscopy (1500×. For FS and ME, specimens were prepared according to the ISO 4049 specifications (n = 10. Statistical analysis of the data was performed with one-way ANOVA and the Tukey test. TPH Spectrum presented significantly higher LPS values (29.45 µm. Grandio had significantly higher mean values for FS (141.07 MPa and ME (13.91 GPa. The relationship between modulus of elasticity and polymerization shrinkage is the main challenge for maintenance of the adhesive interface, thus composites presenting high shrinkage values, associated with a high modulus of elasticity tend to disrupt the adhesive interface under polymerization.
Jurowski, Krystian; Grzeszczyk, Stefania
2018-03-22
In this paper, the relationship between the static and dynamic elastic modulus of concrete and the relationship between the static elastic modulus and compressive strength of concrete have been formulated. These relationships are based on investigations of different types of concrete and take into account the type and amount of aggregate and binder used. The dynamic elastic modulus of concrete was tested using impulse excitation of vibration and the modal analysis method. This method could be used as a non-destructive way of estimating the compressive strength of concrete.
Jelinska, N.; Kalnins, M.; Kovalovs, A.; Chate, A.
2015-11-01
By the surface response method, a regression equation is constructed, and the tensile elastic modulus of films made from polyvinyl alcohol/polyvinyl acetate (PVA/PVAc) blends filled with montmorillonite clay and microcrystalline cellulose nanoparticles is investigated. It is established that the introduction of the nanoparticles improves the mechanical properties of the blends in tension considerably: their strength and elastic modulus increase with content of the particles. Using the regression equation, the optimum composition of nanoparticlefilled PVA/PVAc blends with the highest value of elastic modulus is found.
Jurowski, Krystian; Grzeszczyk, Stefania
2018-01-01
In this paper, the relationship between the static and dynamic elastic modulus of concrete and the relationship between the static elastic modulus and compressive strength of concrete have been formulated. These relationships are based on investigations of different types of concrete and take into account the type and amount of aggregate and binder used. The dynamic elastic modulus of concrete was tested using impulse excitation of vibration and the modal analysis method. This method could be used as a non-destructive way of estimating the compressive strength of concrete. PMID:29565830
Internal strain estimation for quantification of human heel pad elastic modulus: A phantom study
DEFF Research Database (Denmark)
Holst, Karen; Liebgott, Hervé; Wilhjelm, Jens E.
2013-01-01
Shock absorption is the most important function of the human heel pad. However, changes in heel pad elasticity, as seen in e.g. long-distance runners, diabetes patients, and victims of Falanga torture are affecting this function, often in a painful manner. Assessment of heel pad elasticity...... is usually based on one or a few strain measurements obtained by an external load-deformation system. The aim of this study was to develop a technique for quantitative measurements of heel pad elastic modulus based on several internal strain measures from within the heel pad by use of ultrasound images. Nine...... heel phantoms were manufactured featuring a combination of three heel pad stiffnesses and three heel pad thicknesses to model the normal human variation. Each phantom was tested in an indentation system comprising a 7MHz linear array ultrasound transducer, working as the indentor, and a connected load...
Directory of Open Access Journals (Sweden)
Tomasz Topoliński
2012-01-01
Full Text Available Trabecular bone cores were collected from the femoral head at the time of surgery (hip arthroplasty. Investigated were 42 specimens, from patients with osteoporosis and coxarthrosis. The cores were scanned used computer microtomography (microCT system at an isotropic spatial resolution of 36 microns. Image stacks were converted to finite element models via a bone voxel-to-element algorithm. The apparent modulus was calculated based on the assumptions that for the elastic properties, E=10 MPa and ν=0.3. The compressive deformation as calculated by finite elements (FE analysis was 0.8%. The models were coarsened to effectively change the resolution or voxel size (from 72 microns to 288 microns or from 72 microns to 1080 microns. The aim of our study is to determine how an increase in the distance between scans changes the elastic properties as calculated by FE models. We tried to find a border value voxel size at which the module values were possible to calculate. As the voxel size increased, the mean voxel volume increased and the FEA-derived apparent modulus decreased. The slope of voxel size versus modulus relationship correlated with several architectural indices of trabecular bone.
Ateş, Filiz; Hug, François; Bouillard, Killian; Jubeau, Marc; Frappart, Thomas; Couade, Mathieu; Bercoff, Jeremy; Nordez, Antoine
2015-08-01
Muscle shear elastic modulus is linearly related to muscle torque during low-level contractions (torque over the entire range of isometric contraction and (ii) the influence of the size of the region of interest (ROI) used to average the shear modulus value. Ten healthy males performed two incremental isometric little finger abductions. The joint torque produced by Abductor Digiti Minimi was considered as an index of muscle torque and elastic modulus. A high coefficient of determination (R(2)) (range: 0.86-0.98) indicated that the relationship between elastic modulus and torque can be accurately modeled by a linear regression over the entire range (0% to 100% of MVC). The changes in shear elastic modulus as a function of torque were highly repeatable. Lower R(2) values (0.89±0.13 for 1/16 of ROI) and significantly increased absolute errors were observed when the shear elastic modulus was averaged over smaller ROI, half, 1/4 and 1/16 of the full ROI) than the full ROI (mean size: 1.18±0.24cm(2)). It suggests that the ROI should be as large as possible for accurate measurement of muscle shear modulus. Copyright © 2015 Elsevier Ltd. All rights reserved.
Printing Three-Dimensional Heterogeneities in the Elastic Modulus of an Elastomeric Matrix.
Abdel Fattah, Abdel Rahman; Ghosh, Suvojit; Puri, Ishwar K
2016-05-04
We present a rapid and controllable method to create microscale heterogeneities in the 3D stiffness of a soft material by printing patterns with a ferrofluid ink. An ink droplet moved through a liquid polydimethylsiloxane (PDMS) volume using an externally applied magnetic field sheds clusters of magnetic nanoparticles (MNPs) in its wake. By varying the field spatiotemporally, a well-defined three-dimensional curvilinear feature is printed that contains MNP clusters. Subsequent cross-linking of the PDMS preserves the feature in place after the magnetic field is removed. Since the ferrofluid ink interferes with the cross-linking of PDMS, a 3D print containing ink density variations leads to corresponding spatial deviations in the elastic modulus of the matrix. The modulus is mapped in the experiments with atomic force microscopy. This rapid method to print 3D heterogeneities in soft matter promises the ability to mimic mechanical variations that occur in natural biomaterials.
Elastic Metamaterials with Simultaneously Negative Effective Shear Modulus and Mass Density
Wu, Ying
2011-09-02
We propose a type of elastic metamaterial comprising fluid-solid composite inclusions which can possess a negative shear modulus and negative mass density over a large frequency region. Such a material has the unique property that only transverse waves can propagate with a negative dispersion while longitudinal waves are forbidden. This leads to many interesting phenomena such as negative refraction, which is demonstrated by using a wedge sample and a significant amount of mode conversion from transverse waves to longitudinal waves that cannot occur on the interface of two natural solids.
Directory of Open Access Journals (Sweden)
André Luis Christoforo
2012-05-01
Full Text Available The current standard NBR 7190/1997 (Project of Timber Structures makes no reference to tests for determining the stiffness and strength in parts of structural lumber; restricting the analysis to bodies-of-tests with small dimensions and without defects. This paper presents an alternative method to determine the longitudinal modulus of elasticity in timber beams, based on the Finite Element Method, as well as the Inverse Analysis Method with an optimization technique. Results show that the methodology proposed by the Brazilian standard can also be applied to pieces of structural dimensions.
Internal strain estimation for quantification of human heel pad elastic modulus: A phantom study.
Holst, Karen; Liebgott, Hervé; Wilhjelm, Jens E; Nikolov, Svetoslav; Torp-Pedersen, Søren T; Delachartre, Philippe; Jensen, Jørgen A
2013-02-01
Shock absorption is the most important function of the human heel pad. However, changes in heel pad elasticity, as seen in e.g. long-distance runners, diabetes patients, and victims of Falanga torture are affecting this function, often in a painful manner. Assessment of heel pad elasticity is usually based on one or a few strain measurements obtained by an external load-deformation system. The aim of this study was to develop a technique for quantitative measurements of heel pad elastic modulus based on several internal strain measures from within the heel pad by use of ultrasound images. Nine heel phantoms were manufactured featuring a combination of three heel pad stiffnesses and three heel pad thicknesses to model the normal human variation. Each phantom was tested in an indentation system comprising a 7MHz linear array ultrasound transducer, working as the indentor, and a connected load cell. Load-compression data and ultrasound B-mode images were simultaneously acquired in 19 compression steps of 0.1mm each. The internal tissue displacement was for each step calculated by a phase-based cross-correlation technique and internal strain maps were derived from these displacement maps. Elastic moduli were found from the resulting stress-strain curves. The elastic moduli made it possible to distinguish eight of nine phantoms from each other according to the manufactured stiffness and showed very little dependence of the thickness. Mean elastic moduli for the three soft, the three medium, and the three hard phantoms were 89kPa, 153kPa, and 168kPa, respectively. The combination of ultrasound images and force measurements provided an effective way of assessing the elastic properties of the heel pad due to the internal strain estimation. Copyright © 2012 Elsevier B.V. All rights reserved.
International Nuclear Information System (INIS)
Ondracek, G.; Thuemmler, F.
1979-01-01
A set of equations derived demonstrates quantitatively the influence of closed pores on the conductivity as well as on Youngsmodulus of elasticity of sintered materials. There are three microstructural parameters following from the theoretical derivation controlling the porosity effect on the properties, which are the total porosity, the form factor and the orientation factor of the pores. By quantitative microstructure analysis these factors become available providing together with the equations the tool - to calculate the conductivity and Youngs modulus of elasticity from microstructural quantities of sintered materials thus substituting direct property measurements by quantitative microstructure analysis if desired - to endeaver technologically optimum microstructures to obtain theoretically predicted special property values and to precalculate property alterations by microstructure variations ('taylor-made-materials') - to supplement the conventional microstructural quality control by calculated property data. (orig.) [de
Hardness and Elastic Modulus on Six-Fold Symmetry Gold Nanoparticles
Ramos, Manuel; Ortiz-Jordan, Luis; Hurtado-Macias, Abel; Flores, Sergio; Elizalde-Galindo, José T.; Rocha, Carmen; Torres, Brenda; Zarei-Chaleshtori, Maryam; Chianelli, Russell R.
2013-01-01
The chemical synthesis of gold nanoparticles (NP) by using gold (III) chloride trihydrate (HAuCl∙3H2O) and sodium citrate as a reducing agent in aqueous conditions at 100 °C is presented here. Gold nanoparticles areformed by a galvanic replacement mechanism as described by Lee and Messiel. Morphology of gold-NP was analyzed by way of high-resolution transmission electron microscopy; results indicate a six-fold icosahedral symmetry with an average size distribution of 22 nm. In order to understand the mechanical behaviors, like hardness and elastic moduli, gold-NP were subjected to nanoindentation measurements—obtaining a hardness value of 1.72 GPa and elastic modulus of 100 GPa in a 3–5 nm of displacement at the nanoparticle’s surface. PMID:28809302
Bending Elasticity Modulus of Giant Vesicles Composed of Aeropyrum Pernix K1 Archaeal Lipid
Directory of Open Access Journals (Sweden)
Julia Genova
2015-03-01
Full Text Available Thermally induced shape fluctuations were used to study elastic properties of giant vesicles composed of archaeal lipids C25,25-archetidyl (glucosyl inositol and C25,25-archetidylinositol isolated from lyophilised Aeropyrum pernix K1 cells. Giant vesicles were created by electroformation in pure water environment. Stroboscopic illumination using a xenon flash lamp was implemented to remove the blur effect due to the finite integration time of the camera and to obtain an instant picture of the fluctuating vesicle shape. The mean weighted value of the bending elasticity modulus kc of the archaeal membrane determined from the measurements meeting the entire set of qualification criteria was (1.89 ± 0.18 × 10−19 J, which is similar to the values obtained for a membrane composed of the eukaryotic phospholipids SOPC (1.88 ± 0.17 × 10−19 J and POPC (2.00 ± 0.21 ´ 10−19 J. We conclude that membranes composed of archaeal lipids isolated from Aeropyrum pernix K1 cells have similar elastic properties as membranes composed of eukaryotic lipids. This fact, together with the importance of the elastic properties for the normal circulation through blood system, provides further evidence in favor of expectations that archaeal lipids could be appropriate for the design of drug delivery systems.
Supersonic shear imaging provides a reliable measurement of resting muscle shear elastic modulus
International Nuclear Information System (INIS)
Lacourpaille, Lilian; Hug, François; Bouillard, Killian; Nordez, Antoine; Hogrel, Jean-Yves
2012-01-01
The aim of the present study was to assess the reliability of shear elastic modulus measurements performed using supersonic shear imaging (SSI) in nine resting muscles (i.e. gastrocnemius medialis, tibialis anterior, vastus lateralis, rectus femoris, triceps brachii, biceps brachii, brachioradialis, adductor pollicis obliquus and abductor digiti minimi) of different architectures and typologies. Thirty healthy subjects were randomly assigned to the intra-session reliability (n = 20), inter-day reliability (n = 21) and the inter-observer reliability (n = 16) experiments. Muscle shear elastic modulus ranged from 2.99 (gastrocnemius medialis) to 4.50 kPa (adductor digiti minimi and tibialis anterior). On the whole, very good reliability was observed, with a coefficient of variation (CV) ranging from 4.6% to 8%, except for the inter-operator reliability of adductor pollicis obliquus (CV = 11.5%). The intraclass correlation coefficients were good (0.871 ± 0.045 for the intra-session reliability, 0.815 ± 0.065 for the inter-day reliability and 0.709 ± 0.141 for the inter-observer reliability). Both the reliability and the ease of use of SSI make it a potentially interesting technique that would be of benefit to fundamental, applied and clinical research projects that need an accurate assessment of muscle mechanical properties. (note)
Influence of wood moisture content on the modulus of elasticity in compression parallel to the grain
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Diogo Aparecido Lopes Silva
2012-04-01
Full Text Available Brazilian Standard ABNT NBR7190:1997 for timber structures design, adopts a first degree equation to describe the influence of wood moisture content. Periodically, when necessary, the referred standard is revised in order to analyze inconsistencies and to adopt considerations according new realities verified. So, the present paper aims to examine the adequacy of its equation which corrects to 12% of moisture the values of rigidity properties obtained on experimental tests. To quantify the moisture influence on modulus of elasticity, it was applied tests of compression parallel to the grain for six specimens of different strength classes, considering nominal moisture of 12; 20; 25; 30%. As results, modulus of elasticity in the moisture range 25-30% showed statistically equivalents, and was obtained a first degree equation to correlate the studied variables which leads to statically equivalent estimations when compared with results by ABNT NBR7190:1997 equation. However, it was indicated to maintain the current expression for the next text of the referred document review, without prejudice to statistical significance of the estimates.
Crack arrest within teeth at the dentinoenamel junction caused by elastic modulus mismatch.
Bechtle, Sabine; Fett, Theo; Rizzi, Gabriele; Habelitz, Stefan; Klocke, Arndt; Schneider, Gerold A
2010-05-01
Enamel and dentin compose the crowns of human teeth. They are joined at the dentinoenamel junction (DEJ) which is a very strong and well-bonded interface unlikely to fail within healthy teeth despite the formation of multiple cracks within enamel during a lifetime of exposure to masticatory forces. These cracks commonly are arrested when reaching the DEJ. The phenomenon of crack arrest at the DEJ is described in many publications but there is little consensus on the underlying cause and mechanism. Explanations range from the DEJ having a larger toughness than both enamel and dentin up to the assumption that not the DEJ itself causes crack arrest but the so-called mantle dentin, a thin material layer close to the DEJ that is somewhat softer than the bulk dentin. In this study we conducted 3-point bending experiments with bending bars consisting of the DEJ and surrounding enamel and dentin to investigate crack propagation and arrest within the DEJ region. Calculated stress intensities around crack tips were found to be highly influenced by the elastic modulus mismatch between enamel and dentin and hence, the phenomenon of crack arrest at the DEJ could be explained accordingly via this elastic modulus mismatch. Copyright 2010 Elsevier Ltd. All rights reserved.
Estimation of Elastic Modulus of Intact Rocks by Artificial Neural Network
Ocak, Ibrahim; Seker, Sadi Evren
2012-11-01
The modulus of elasticity of intact rock ( E i) is an important rock property that is used as an input parameter in the design stage of engineering projects such as dams, slopes, foundations, tunnel constructions and mining excavations. However, it is sometimes difficult to determine the modulus of elasticity in laboratory tests because high-quality cores are required. For this reason, various methods for predicting E i have been popular research topics in recently published literature. In this study, the relationships between the uniaxial compressive strength, unit weight ( γ) and E i for different types of rocks were analyzed, employing an artificial neural network and 195 data obtained from laboratory tests carried out on cores obtained from drilling holes within the area of three metro lines in Istanbul, Turkey. Software was developed in Java language using Weka class libraries for the study. To determine the prediction capacity of the proposed technique, the root-mean-square error and the root relative squared error indices were calculated as 0.191 and 92.587, respectively. Both coefficients indicate that the prediction capacity of the study is high for practical use.
Directory of Open Access Journals (Sweden)
Ahmadian Khoshemehr Leila
2009-09-01
Full Text Available Background: Luting agents are used to attach indirect restoration into or on the tooth. Poor mechanical properties of cement may be a cause of fracture of this layer and lead to caries and restoration removal. The purpose of this study was to compare the elastic modulus and compressive strength of Ariadent (A Poly and Harvard polycarboxylate (H Poly cements and Vitremer resin modified glass ionomer (RGl.Materials & Methods: In this experimental study 15 specimens were prepared form each experimental cement in Laboratory of Tehran Oil Refining Company. The cylindrical specimens were compressed in Instron machine after 24 hours. Elastic modulus and compressive strength were calculated from stress/strain curve of each specimen. One way ANOVA and Tukey tests were used for statistical analysis and P values<0.05 were considered to be statistically significant.Results: The mean elastic modulus and mean compressive strength were 2.2 GPa and 87.8MPa in H poly, 2.4 GPa and 56.5 MPa in A Poly, and 0.8GPa and 105.6 MPa in RGI, respectively. Statistical analysis showed that compressive strength and elastic modulus of both polycarboxylate cements were significantly different from hybrid ionomer (P<0.05, but the difference between elastic modulus of two types of polycarboxilate cements was not statistically significant. Compressive strength of two polycarboxilate cements were significantly different (P<0.05. Conclusion: An ideal lutting agent must have the best mechanical properties. Between the tested luttins RGl cement had the lowest elastic modulus and the highest compressive strength, but the A poly cement had the highest elastic modulus and the lowest compressive strength. Therefore none of them was the best.
Temperature dependence of bulk modulus and second-order elastic constants
International Nuclear Information System (INIS)
Singh, P.P.; Kumar, Munish
2004-01-01
A simple theoretical model is developed to investigate the temperature dependence of the bulk modulus and second order elastic constants. The method is based on the two different approaches viz. (i) the theory of thermal expansivity formulated by Suzuki, based on the Mie-Gruneisen equation of state, (ii) the theory of high-pressure-high-temperature equation of state formulated by Kumar, based on thermodynamic analysis. The results obtained for a number of crystals viz. NaCl, KCl, MgO and (Mg, Fe) 2 SiO 4 are discussed and compared with the experimental data. It is concluded that the Kumar formulation is far better that the Suzuki theory of thermal expansivity
A new approach to measure the elasticity modulus for ceramics using the deformation energy method
International Nuclear Information System (INIS)
Foschini, Cesar R.; Souza, Edson A.; Borges, Ana F. S.; Pintao, Carlos A.
2016-01-01
This paper presents an alternative method to measure the modulus of elasticity to traction, E, for relatively limited sample sizes. We constructed a measurement system with a Force sensor (FS) and a Rotation movement sensor (RMS) to obtain a relationship between force (F) and bending (ΔL). It was possible by calculating the strain energy and the work of a constant force to establish a relationship between these quantities; the constant of proportionality in this relationship depends on E, I and L. I and L are the moment of inertia of the uniform cross-section in relation to an oriented axis and length, respectively, of the sample for bending. An expression that could achieve the value of E was deduced to study samples of Y-TZP ceramics. The advantages of this system compared to traditional systems are its low cost and practicality in determining E
A new approach to measure the elasticity modulus for ceramics using the deformation energy method
Energy Technology Data Exchange (ETDEWEB)
Foschini, Cesar R.; Souza, Edson A. [Dept. of EngineeringFeb-UNESPBauru (Brazil); Borges, Ana F. S. [Dept. of MaterialFOB-USP, Bauru (Brazil); Pintao, Carlos A. [Dept. of PhysicsFC-UNESP, Bauru (Brazil)
2016-08-15
This paper presents an alternative method to measure the modulus of elasticity to traction, E, for relatively limited sample sizes. We constructed a measurement system with a Force sensor (FS) and a Rotation movement sensor (RMS) to obtain a relationship between force (F) and bending (ΔL). It was possible by calculating the strain energy and the work of a constant force to establish a relationship between these quantities; the constant of proportionality in this relationship depends on E, I and L. I and L are the moment of inertia of the uniform cross-section in relation to an oriented axis and length, respectively, of the sample for bending. An expression that could achieve the value of E was deduced to study samples of Y-TZP ceramics. The advantages of this system compared to traditional systems are its low cost and practicality in determining E.
Mullin, Scott; Panday, Ashoutosh; Balsara, Nitash Pervez; Singh, Mohit; Eitouni, Hany Basam; Gomez, Enrique Daniel
2014-04-22
A polymer that combines high ionic conductivity with the structural properties required for Li electrode stability is useful as a solid phase electrolyte for high energy density, high cycle life batteries that do not suffer from failures due to side reactions and dendrite growth on the Li electrodes, and other potential applications. The polymer electrolyte includes a linear block copolymer having a conductive linear polymer block with a molecular weight of at least 5000 Daltons, a structural linear polymer block with an elastic modulus in excess of 1.times.10.sup.7 Pa and an ionic conductivity of at least 1.times.10.sup.-5 Scm.sup.-1. The electrolyte is made under dry conditions to achieve the noted characteristics. In another aspect, the electrolyte exhibits a conductivity drop when the temperature of electrolyte increases over a threshold temperature, thereby providing a shutoff mechanism for preventing thermal runaway in lithium battery cells.
Kim, Wansun; Lee, Inhwa; Yoon Kim, Dong; Yu, Youn-Yeol; Jung, Hae-Yoon; Kwon, Seyeoul; Seo Park, Weon; Kim, Taek-Soo
2017-05-12
To protect brittle layers in organic photovoltaic devices, the mechanical neutral plane strategy can be adopted through placing the brittle functional materials close to the neutral plane where stress and strain are zero during bending. However, previous research has been significantly limited in the location and number of materials to protect through using a single neutral plane. In this study, multiple neutral planes are generated using low elastic modulus adhesives and are controlled through quantitative analyses in order to protect the multiple brittle materials at various locations. Moreover, the protection of multiple brittle layers at various locations under both concave and convex bending directions is demonstrated. Multilayer structures that have soft adhesives are further analyzed using the finite element method analysis in order to propose guidelines for structural design when employing multiple neutral planes.
Hosseini, Motahare Sadat; Tazzoli-Shadpour, Mohammad; Amjadi, Issa; Haghighipour, Nooshin; Shokrgozar, Mohammad Ali; Ghafourian Boroujerdnia, Mehri
2012-01-01
Background Substrates in medical science are hydrophilic polymers undergoing volume expansion when exposed to culture medium that influenced on cell attachment. Although crosslinking by chemical agents could reduce water uptake and promote mechanical properties, these networks would release crosslinking agents. In order to overcome this weakness, silicone rubber is used and reinforced by nanoclay. Objectives Attempts have been made to prepare nanocomposites based on medical grade HTV silicone rubber (SR) and organo-modified montmorillonite (OMMT) nanoclay with varying amounts of clay compositions. Materials and Methods Incorporation of nanocilica platelets into SR matrix was carried out via melt mixing process taking advantage of a Brabender internal mixer. The tensile elastic modulus of nanocomposites was measured by performing tensile tests on the samples. Produced polydimetylsiloxane (PDMS) composites with different flexibilities and crosslink densities were employed as substrates to investigate biocompatibility, cell compaction, and differential behaviors. Results The results presented here revealed successful nanocomposite formation with SR and OMMT, resulting in strong PDMS-based materials. The results showed that viability, proliferation, and spreading of cells are governed by elastic modulus and stiffness of samples. Furthermore, adipose derived stem cells (ADSCs) cultured on PDMS and corresponding nanocomposites could retain differentiation potential of osteocytes in response to soluble factors, indicating that inclusion of OMMT would not prevent osteogenic differentiation. Moreover, better spread out and proliferation of cells was observed in nanocomposite samples. Conclusions Considering cell behavior and mechanical properties of nanobiocomposites it could be concluded that silicone rubber substrate filled by nanoclay are a good choice for further experiments in tissue engineering and medical regeneration due to its cell compatibility and differentiation
International Nuclear Information System (INIS)
Davidson, M.; Bastian, S.; Markley, F.
1992-04-01
Understanding the short term elastic properties, (i.e. the instantaneous modulus) of Kapton is essential in determining the loss of prestress during storage and operation of SSC dipole magnets. The magnet prestress contributes directly to the coil response to the Lorentz forces during ramping. The instantaneous modulus is important in extrapolating short term stress relaxation data to longer times. Most theoretical fits assume a time independent component and a time dependent component. The former may be represented by the Kapton modulus near zero K where all relaxation processes have been ''frozen'' out. Modulus measurements at 77K and 4.2K may point to a correct value for the near zero K modulus. Three companion papers presented at this conference will be: ''Stress Relaxation in SSC 50 mm Dipole Coils'' ''Temperature Dependence of the Viscoelastic Properties of SSC Coil Insulation (Kapton)'' ''Theoretical Methods for Creep and Stress Relaxation Studies of SSC Coil.''
Jody D. Gray; Shawn T. Grushecky; James P. Armstrong
2008-01-01
Moisture content has a significant impact on mechanical properties of wood. In recent years, stress wave velocity has been used as an in situ and non-destructive method for determining the stiffness of wooden elements. The objective of this study was to determine what effect moisture content has on stress wave velocity and dynamic modulus of elasticity. Results...
Static modulus of elasticity of concrete measured by the ultrasonic method
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Sena Rodrigues, S.
2003-12-01
Full Text Available Lately, a huge number of accidents caused by problems found in the durability of concrete structures due to inappropriate project design, lack of control of quality during the project s execution, inadequate maintenance practices and an aggressive environment has been reported. This finding has required from the professionals constant inspections and evaluations of the real conditions of all concrete structures. In order to perform those inspections, one should know not only the elastic modulus to analyze the concrete structural behaviour but also to investigate its performance, since the strains may yield cracks able to compromise the durability- of structures. Non-destructive testing techniques, particularly the ultrasonic testing, are performed to evaluate and determine the quality of a concrete structure or element. Currently, such essays have been widely researched and analyzed all over the world because they enable the examination of structures without damaging them. The purpose of the present study was to correlate the ultrasonic pulse velocity and the elastic modulus of several concrete specimens molded with a range of water-cement ratios, different kinds of aggregates and curing methods. All the concrete specimens were tested in different ages to determine the pulse velocity and the static modulus of elasticity standardized according to KBR 8522, through mechanical extensometers, electrical strain gauge and LVTD inductive transducer.
Recientemente se ha registrado un gran número de accidentes causados por problemas relacionados con la durabilidad de las estructuras de hormigón y debidos a un inadecuado proyecto de diseño, ausencia de control de calidad durante la ejecución del proyecto, prácticas inadecuadas de construcción y un ambiente agresivo. Este hallazgo ha dado lugar a que los ingenieros realicen constantes inspecciones y evaluaciones de la condición real de todas las estructuras de hormigón. Para llevar a cabo
Karimi, Alireza; Navidbakhsh, Mahdi; Alizadeh, Mansour; Razaghi, Reza
2014-10-01
There have been different stress-strain definitions to measure the elastic modulus of spongy materials, especially polyvinyl alcohol (PVA) sponge. However, there is no agreement as to which stress-strain definition should be implemented. This study was aimed to show how different results are given by the various definitions of stress-strain used, and to recommend a specific definition when testing spongy materials. A fabricated PVA sponge was subjected to a series of tensile tests in order to measure its mechanical properties. Three stress definitions (second Piola-Kichhoff stress, engineering stress, and true stress) and four strain definitions (Almansi-Hamel strain, Green-St. Venant strain, engineering strain, and true strain) were used to determine the elastic modulus. The results revealed that the Almansi-Hamel strain definition exhibited the highest non-linear stress-strain relation and, as a result, may overestimate the elastic modulus at different stress definitions (second Piola-Kichhoff stress, engineering stress, and true stress). The Green-St. Venant strain definition failed to address the non-linear stress-strain relation using different definitions of stress and invoked an underestimation of the elastic modulus values. Engineering stress and strain definitions were only valid for small strains and displacements, which make them impractical when analyzing spongy materials. The results showed that the effect of varying the stress definition on the maximum stress measurements was significant but not when calculating the elastic modulus. It is important to consider which stress-strain definition is employed when characterizing the mechanical properties of spongy materials. Although the true stress-true strain definition exhibits a non-linear relation, we favor it in spongy materials mechanics as it gives more accurate measurements of the material's response using the instantaneous values.
Impact Of Elastic Modulus Degradation On Springback In Sheet Metal Forming
International Nuclear Information System (INIS)
Halilovic, Miroslav; Stok, Boris; Vrh, Marko
2007-01-01
Strain recovery after removal of forming loads, commonly defined as springback, is of great concern in sheet metal forming, in particular with regard to proper prediction of the final shape of the part. To control the problem a lot of work has been done, either by minimizing the springback on the material side or by increasing the estimation precision in corresponding process simulations. Unfortunately, by currently available software springback still cannot be adequately predicted, because most analyses of springback are using linear, isotropic and constant Young's modulus and Poisson's ratio. But, as it was measured and reported, none of it is true. The aim of this work is to propose an upgraded mechanical model which takes evolution of damage and related orthotropic stiffness degradation into account. Damage is considered by inclusion of ellipsoidal cavities, and their influence on the stiffness degradation is taken in accordance with the Mori-Tanaka theory, adopting the GTN model for plastic flow. In order to improve the numerical springback prediction, two major things are important: first, the correct evaluation of the stress-strain state at the end of the forming process, and second, correctness of the elastic properties used in the elastic relaxation analysis. Since in modelling of the forming process we adopt a damage constitutive model with orthotropic stiffness degradation considered, a corresponding damage parameters identification upon specific experimental tests data must be performed first, independently of the metal forming modelling. An improved identification of material parameters, which simultaneously considers tensile test results with different type of specimens and using neural network, is proposed. With regard to the case in which damage in material is neglected it is shown in the article how the springback of a formed part differs, when we take orthotropic damage evolution into consideration
Directory of Open Access Journals (Sweden)
Hakan Keskin
2016-04-01
Full Text Available The aim of this study was to investigate the effects of impregnation with Tanalith-E on the bending strengths and modulus of elasticity in bending of some wood types. The test samples prepared from beech, oak, walnut, poplar, ash and pine wood materials - that are of common use in the forest products industry of TURKEY - according to TS 345, were treated with according to ASTM D 1413-76 substantially. Un-impregnated samples according to impregnated wood materials, the bending strengths in beech to 6.83%, 5.12% in ash, 5.93% in pine, the elasticity module values to 7.15% in oak and ash, at a rate of 6.58% in the higher were found. The highest values of bending strengths and modulus of elasticity in bending were obtained in beech and ash woods impregnated with Tanalith-E, whereas the lowest values were obtained in the poplar wood.
Bendable Electro-Acoustic Transducer Fabricated Utilizing Frequency Dispersion of Elastic Modulus
Miyoshi, Tetsu; Ohga, Juro
2013-09-01
To realize the speaker diaphragm that can be united with a flexible display without deteriorating lightweight properties and flexibility, a novel bendable electro-acoustic transducer (BEAT) based on 0-3-type piezoelectric composites has been developed. To overcome the trade-off between flexibility and the transmission efficiency of vibration energy, a viscoelastic polymer that has local maximum points in the loss factor as well as large frequency dispersion in the storage modulus near room temperature was employed as the matrix of the piezoelectric composite layer. Against the comparatively slow (10 Hz or less) deformation from the outside, the viscoelastic matrix is viscous enough to prevent cracking and delamination. On the other hand, in the audible range (20 Hz to 20 kHz), the matrix is elastic enough to transmit piezoelectric vibration energy, maintaining a moderately large loss factor as well as a high sound velocity. For the first time, we successfully demonstrated a rollable speaker that can continue to generate a high-quality sound while being rolled and unrolled repeatedly onto a cylinder with a curvature radius of 4 mm.
Solute accumulation and elastic modulus changes in six radiata pine breeds exposed to drought.
De Diego, N; Sampedro, M C; Barrio, R J; Saiz-Fernández, I; Moncaleán, P; Lacuesta, M
2013-01-01
Drought is one of the main abiotic factors that determine forest species growth, survival and productivity. For this reason, knowledge of plant drought response and the identification of physiological traits involved in stress tolerance will be of interest to breeding programs. In this work, several Pinus radiata D. Don breeds from different geographical origins were evaluated along a water stress period (4 weeks) and subsequent rewatering (1 week), showing different responses among them. Leaf water potential (Ψ(leaf)) and osmotic potential decreases were accompanied by a variation in the total relative water content (RWC, %). The most tolerant breeds presented the lowest leaf water potential and RWC at turgor loss point, and showed the lowest elastic modulus (ε) values. A high ε value was a characteristic of a less-drought-tolerant plant and was related to membrane alterations (high electrolyte leakage percentages) that could favor cell water loss. Of the group of solutes that contributed to osmotic adjustment, soluble carbohydrates were the most abundant, although stressed plants also increased their content of free amino acids [mainly proline (Pro) and glutamic acid (Glu), and γ-aminobutyric acid (GABA)] and free polyamines. In addition, the most sensitive breeds had a higher GABA/Glu ratio. After rewatering, Pro and GABA were higher in rehydrated plants than in controls.
Yu, Huiling; Liang, Hao; Lin, Xue; Zhang, Yizhuo
2018-04-01
A nondestructive methodology is proposed to determine the modulus of elasticity (MOE) of Fraxinus mandschurica samples by using near-infrared (NIR) spectroscopy. The test data consisted of 150 NIR absorption spectra of the wood samples obtained using an NIR spectrometer, with the wavelength range of 900 to 1900 nm. To eliminate the high-frequency noise and the systematic variations on the baseline, Savitzky-Golay convolution combined with standard normal variate and detrending transformation was applied as data pretreated methods. The uninformative variable elimination (UVE), improved by the evolutionary Monte Carlo (EMC) algorithm and successive projections algorithm (SPA) selected three characteristic variables from full 117 variables. The predictive ability of the models was evaluated concerning the root-mean-square error of prediction (RMSEP) and coefficient of determination (Rp2) in the prediction set. In comparison with the predicted results of all the models established in the experiments, UVE-EMC-SPA-LS-SVM presented the best results with the smallest RMSEP of 0.652 and the highest Rp2 of 0.887. Thus, it is feasible to determine the MOE of F. mandschurica using NIR spectroscopy accurately.
Čapek, Jaroslav; Machová, Markéta; Fousová, Michaela; Kubásek, Jiří; Vojtěch, Dalibor; Fojt, Jaroslav; Jablonská, Eva; Lipov, Jan; Ruml, Tomáš
2016-12-01
Recently, porous metallic materials have been extensively studied as candidates for use in the fabrication of scaffolds and augmentations to repair trabecular bone defects, e.g. in surroundings of joint replacements. Fabricating these complex structures by using common approaches (e.g., casting and machining) is very challenging. Therefore, rapid prototyping techniques, such as selective laser melting (SLM), have been investigated for these applications. In this study, we characterized a highly porous (87 vol.%) 316L stainless steel scaffold prepared by SLM. 316L steel was chosen because it presents a biomaterial still widely used for fabrication of joint replacements and, from the practical point of view, use of the same material for fabrication of an augmentation and a joint replacement is beneficial for corrosion prevention. The results are compared to the reported properties of two representative nonporous 316L stainless steels prepared either by SLM or casting and subsequent hot forging. The microstructural and mechanical properties and the surface chemical composition and interaction with the cells were investigated. The studied material exhibited mechanical properties that were similar to those of trabecular bone (compressive modulus of elasticity ~0.15GPa, compressive yield strength ~3MPa) and cytocompatibility after one day that was similar to that of wrought 316L stainless steel, which is a commonly used biomaterial. Based on the obtained results, SLM is a suitable method for the fabrication of porous 316L stainless steel scaffolds with highly porous structures. Copyright © 2016 Elsevier B.V. All rights reserved.
DEFF Research Database (Denmark)
Gaihede, Michael Lyhne; Donghua, Liao; Gregersen, H.
2007-01-01
The quasi-static elastic properties of the tympanic membrane system can be described by the areal modulus of elasticity determined by a middle ear model. The response of the tympanic membrane to quasi-static pressure changes is determined by its elastic properties. Several clinical problems are r...... finite element analyses. In vivo estimates of Young's modulus in this study were a factor 2-3 smaller than previously found in vitro. No significant age-related differences were found in the elastic properties as expressed by the areal modulus....
Directory of Open Access Journals (Sweden)
Jakub Ďureje
2017-11-01
Full Text Available A modulus of elasticity was determined for eight differently foamed cement paste samples. Samples were loaded in the laboratory by a hydraulic press. The force acting on the sample was read directly from the laboratory press. Digital Image Correlation (DIC analysis were used to draw deformations. Before loading pressure test was applied a random contrast pattern to the samples. Samples were captured by the camera in a one-second interval during the loading pressure test. The images were edited in the Adobe Photoshop Lightroom and then evaluated using Ncorr software. The result is a vertical and horizontal shift field. On the basis of the results obtained, it was possible to calculate the modulus of elasticity of each sample.
Directory of Open Access Journals (Sweden)
André Luis Christoforo
2012-12-01
Full Text Available This paper proposes an alternative method of calculation based on the Least Squares Method to determine the longitudinal modulus of elasticity in structural-sized wooden beams. The developed equations require knowledge of three points of displacements, allowing greater reliability on the dependent variable when using the static four-point bending test. Using the Jatobá (Hymenaea sp wood in the study, the methodology proposed here was used in combination with a simplified one, requiring knowledge of displacement only at the midpoint of the beam in order to compare the results among them. Results show statistical equivalence between the models, indicating a good approximation of the simplified model for calculating the modulus of elasticity in wooden structural bending here evaluated.
Cheng Guan; Houjiang Zhang; Lujing Zhou; Xiping Wang
2015-01-01
A vibration testing method based on free vibration theory in a ââfreeâfreeâ support condition was investigated for evaluating the modulus of elasticity (MOE) of full-size wood composite panels (WCPs). Vibration experiments were conducted on three types of WCPs (medium density fibreboard, particleboard, and plywood) to determine the dynamic MOE of the panels. Static...
Issa, Yaser; Watts, David C; Boyd, Daniel; Price, Richard B
2016-04-01
To determine the nanohardness and elastic moduli of two bulk-fill resin based composites (RBCs) at increasing depths from the surface and increasing distances laterally from the center after light curing. Two bulk-fill dental RBCs: Tetric EvoCeram Bulk Fill (TECBF) and Filtek Bulk Fill Flowable (FBFF) were light cured in a metal mold with a 6mm diameter and a 10mm long semi-circular notch. The RBCs were photo-polymerized for 10s using a light emitting diode (LED) Bluephase Style curing light, with the original light probe that lacked the homogenizer. This light has two blue light and one violet light LED emitters. By changing the probe orientation over the mold, the light output from only two LEDs reached the RBC. Measurements were made using: (i) the light from one violet and one blue LED, and (ii) the light from the two blue LEDs. Five specimens of each RBC were made using each LED orientation (total 20 specimens). Specimens were then stored in the dark at 37°C for 24h. Fifty indents were made using an Agilent G200 nanoindentor down to 4mm from the surface and 2.5mm right and left of the centerline. The results were analyzed (alpha=0.05) using multiple paired-sample t-tests, ANOVA, Bonferroni post-hoc tests, and Pearson correlations. The elastic modulus and nanohardness varied according to the depth and the distance from the centerline. For TECBF, no significant difference was found between the spatial variations in the elastic modulus or hardness values when violet-blue or blue-blue LEDs were used. For FBFF, the elastic modulus and nanohardness on the side exposed to the violet emitter were significantly less than the side exposed to the blue emitter. A strong correlation between nanohardness and elastic modulus was found in all groups (r(2)=0.9512-0.9712). Resin polymerization was not uniform throughout the RBC. The nanohardness and elastic modulus across two RBC materials were found to decline differently according to the orientation of the violet and blue
Gaspar Junior, Alfredo de Aquino; Lopes, Manuela Wanderley Ferreira; Gaspar, Gabriela da Silveira; Braz, Rodivan
2009-01-01
The objective of this study was to compare the flexural strength and elasticity modulus of two types of staple reinforcement fibers, Interlig - Angelus/glass (Londrina, PR, Brazil) and Connect - KerrLab(R)/polyethylene (MFG Co., West Collins Orange, CA, USA), which are widely used in Dentistry for chairside use, after varying the number of layers employed and submitting or not to thermocycling. This study was performed on 72 specimens, divided into 8 groups: G1 - single layer of Interlig fibers without thermocycling; G2 - double layer of Interlig fibers without thermocycling; G3 - single layer of Interlig fibers with thermocycling; and G4 - double layer of Interlig fibers with thermocycling; G5 - single layer of Connect fibers without termocycling; G6 - double layer of Connect fibers without termocycling; G7 - single layer of Connect fibers with termocycling; G8 - double layer of Connect fibers with termocycling. For each group, values for flexural strength and elasticity modulus were obtained. The polyethylene fiber employed in a double layer presented the highest flexural strength (p elasticity modulus, when compared to the other groups (p < 0.05). Within the limits of this study, it was concluded that the polyethylene fiber in a double layer appears to be more resistant, regardless of whether it was submitted to thermocycling or not.
White, Nathan J; Martin, Erika J; Brophy, Donald F; Ward, Kevin R
2011-07-01
A significant proportion of severely injured patients develop early coagulopathy, characterized by abnormal clot formation, which impairs resuscitation and increases mortality. We have previously demonstrated an isolated decrease in clot strength by thrombelastography in a swine model of nonresuscitated traumatic shock. In order to more closely examine platelet-fibrin interactions in this setting, we define the observed decrease in clot strength in terms of platelet-induced clot contraction and clot elastic modulus using the Hemostasis Analysis System (HAS) (Hemodyne Inc., Richmond, Virginia, USA). Whole blood was sampled for HAS measurements, metabolic measurements, cell counts, and fibrinogen concentration at baseline prior to injury and again at a predetermined level of traumatic shock defined by oxygen debt. Male swine (N=17) received femur fracture and controlled arterial hemorrhage to achieve an oxygen debt of 80 ml/kg. Platelet counts were unchanged, but fibrinogen concentration was reduced significantly during shock (167.6 vs. 66.7 mg/dl, P=0.0007). Platelet contractile force generated during clot formation did not change during shock (11.7 vs. 10.4 kdynes, P=0.41), but clot elastic modulus was dynamically altered, resulting in a lower final value (22.9 vs. 17.3 kdynes/cm, Pshock, platelet function was preserved, whereas terminal clot elastic modulus was reduced during shock in a manner most consistent with early changes in the mechanical properties of the developing fibrin fiber network.
Hamza, A A; Sokkar, T Z N; El-Farahaty, K A; Raslan, M I
2014-06-01
A novel optical setup for simultaneous capturing of photoelastic and two-beam interference patterns was designed. The designed optical setup was used to simultaneously record two types of patterns. The first pattern is two-beam interference pattern, and the second one is photoelastic interference pattern produced by objects under stress. This simultaneous capturing of the two patterns allowed us to calculate the full-field distribution of the elasticity modulus profile of fibres. A mathematical expression of the profile of the elasticity modulus was derived. This was applied to evaluate the elasticity modulus of anisotropic isotactic polypropylene fibres during stretching processes. The profile of the elasticity modulus was determined for both static and dynamic in situ cases where the propagation of different structural deformations was observed and studied using the designed optical setup. Patterns were given for illustration. © 2014 The Authors Journal of Microscopy © 2014 Royal Microscopical Society.
The role of an effective isotropic tissue modulus in the elastic properties of cancellous bone
Kabel, J.; Rietbergen, van B.; Dalstra, M.; Odgaard, A.; Huiskes, H.W.J.
1999-01-01
Conceptually, the elastic characteristics of cancellous bone could be predicted directly from the trabecular morphology-or architecture-and by the elastic properties of the tissue itself. Although hardly any experimental evidence exists, it is often implicitly assumed that tissue anisotropy has a
International Nuclear Information System (INIS)
Gaihede, Michael; Liao Donghua; Gregersen, Hans
2007-01-01
The quasi-static elastic properties of the tympanic membrane system can be described by the areal modulus of elasticity determined by a middle ear model. The response of the tympanic membrane to quasi-static pressure changes is determined by its elastic properties. Several clinical problems are related to these, but studies are few and mostly not comparable. The elastic properties of membranes can be described by the areal modulus, and these may also be susceptible to age-related changes reflected by changes in the areal modulus. The areal modulus is determined by the relationship between membrane tension and change of the surface area relative to the undeformed surface area. A middle ear model determined the tension-strain relationship in vivo based on data from experimental pressure-volume deformations of the human tympanic membrane system. The areal modulus was determined in both a younger (n = 10) and an older (n = 10) group of normal subjects. The areal modulus for lateral and medial displacement of the tympanic membrane system was smaller in the older group (mean = 0.686 and 0.828 kN m -1 , respectively) compared to the younger group (mean = 1.066 and 1.206 kN m -1 , respectively), though not significantly (2p = 0.10 and 0.11, respectively). Based on the model the areal modulus was established describing the summated elastic properties of the tympanic membrane system. Future model improvements include exact determination of the tympanic membrane area accounting for its shape via 3D finite element analyses. In vivo estimates of Young's modulus in this study were a factor 2-3 smaller than previously found in vitro. No significant age-related differences were found in the elastic properties as expressed by the areal modulus
Energy Technology Data Exchange (ETDEWEB)
Gaihede, Michael [Department of Otolaryngology, Head and Neck Surgery, Aalborg Hospital, Aarhus University Hospital, Aalborg (Denmark); Liao Donghua [Centre of Excellence in Visceral Biomechanics and Pain, Aalborg Hospital, Aarhus University Hospital, Aalborg (Denmark); Gregersen, Hans [Centre of Excellence in Visceral Biomechanics and Pain, Aalborg Hospital, Aarhus University Hospital, Aalborg (Denmark)
2007-02-07
The quasi-static elastic properties of the tympanic membrane system can be described by the areal modulus of elasticity determined by a middle ear model. The response of the tympanic membrane to quasi-static pressure changes is determined by its elastic properties. Several clinical problems are related to these, but studies are few and mostly not comparable. The elastic properties of membranes can be described by the areal modulus, and these may also be susceptible to age-related changes reflected by changes in the areal modulus. The areal modulus is determined by the relationship between membrane tension and change of the surface area relative to the undeformed surface area. A middle ear model determined the tension-strain relationship in vivo based on data from experimental pressure-volume deformations of the human tympanic membrane system. The areal modulus was determined in both a younger (n = 10) and an older (n = 10) group of normal subjects. The areal modulus for lateral and medial displacement of the tympanic membrane system was smaller in the older group (mean = 0.686 and 0.828 kN m{sup -1}, respectively) compared to the younger group (mean = 1.066 and 1.206 kN m{sup -1}, respectively), though not significantly (2p = 0.10 and 0.11, respectively). Based on the model the areal modulus was established describing the summated elastic properties of the tympanic membrane system. Future model improvements include exact determination of the tympanic membrane area accounting for its shape via 3D finite element analyses. In vivo estimates of Young's modulus in this study were a factor 2-3 smaller than previously found in vitro. No significant age-related differences were found in the elastic properties as expressed by the areal modulus.
Kushi, Takuto; Sato, Kazuhisa; Unemoto, Atsushi; Hashimoto, Shinichi; Amezawa, Koji; Kawada, Tatsuya
2011-10-01
Mechanical properties such as Young's modulus, shear modulus, Poisson's ratio and internal friction of conventional electrolyte materials for solid oxide fuel cells, Zr0.85Y0.15 O1.93 (YSZ), Zr0.82Sc0.18O1.91 (ScSZ), Zr0.81Sc0.18Ce0.01O2-δ (ScCeSZ), Ce0.9Gd0.1O2-δ (GDC), La0.8Sr0.2Ga0.8Mg0.15Co0.05O3-δ (LSGMC), La0.8Sr0.2Ga0.8Mg0.2O3-δ (LSGM), were evaluated by a resonance method at temperatures from room temperature to 1273 K in various oxygen partial pressures. The Young's modulus of GDC gradually decreased with increasing temperature in oxidizing conditions. The Young's moduli of the series of zirconia and lanthanum gallate based materials drastically decreased in an intermediate temperature range and increased slightly with increasing temperature at higher temperatures. The Young's modulus of GDC considerably decreased above 823 K in reducing atmospheres in response to the change of oxygen nonstoichiometry. However, temperature dependences of the Young's moduli of ScCeSZ and LSGMC in reducing atmospheres did not show any significant differences with those in oxidizing atmospheres.
DEFF Research Database (Denmark)
Day, J; Ding, Ming; van der Linden, JC
2001-01-01
determined using a combination of finite element models and mechanical testing. The bone tissue modulus was reduced by 60% in the medial condyle of the cases with cartilage damage compared to the control specimens. Neither the presence of cartilage damage nor the anatomic site (medial vs. lateral) affected...
Zipping, entanglement, and the elastic modulus of aligned single-walled carbon nanotube films
Won, Yoonjin; Gao, Yuan; Panzer, Matthew A.; Xiang, Rong; Maruyama, Shigeo; Kenny, Thomas W.; Cai, Wei; Goodson, Kenneth E.
2013-01-01
Reliably routing heat to and from conversion materials is a daunting challenge for a variety of innovative energy technologies––from thermal solar to automotive waste heat recovery systems––whose efficiencies degrade due to massive thermomechanical stresses at interfaces. This problem may soon be addressed by adhesives based on vertically aligned carbon nanotubes, which promise the revolutionary combination of high through-plane thermal conductivity and vanishing in-plane mechanical stiffness. Here, we report the data for the in-plane modulus of aligned single-walled carbon nanotube films using a microfabricated resonator method. Molecular simulations and electron microscopy identify the nanoscale mechanisms responsible for this property. The zipping and unzipping of adjacent nanotubes and the degree of alignment and entanglement are shown to govern the spatially varying local modulus, thereby providing the route to engineered materials with outstanding combinations of mechanical and thermal properties. PMID:24309375
International Nuclear Information System (INIS)
Anderson, C.A.; Smith, P.D.
1978-01-01
The variable modulus-cracking model is capable of predicting the behavior of reinforced concrete structures (such as the reinforced plate under transverse pressure described previously) well into the range of nonlinear behavior including the prediction of the ultimate load. For unreinforced thick-walled concrete vessels under internal pressure the use of elastic--plastic concrete models in finite element codes enhances the apparent ductility of the vessels in contrast to variable modulus-cracking models that predict nearly instantaneous rupture whenever the tensile strength at the inner wall is exceeded. For unreinforced thick-walled end slabs representative of PCRV heads, the behavior predicted by finite element codes using variable modulus-cracking models is much stiffer in the nonlinear range than that observed experimentally. Although the shear type failures and crack patterns that are observed experimentally are predicted by such concrete models, the ultimate load carrying capacity and vessel-ductility are significantly underestimated. It appears that such models do not adequately model such features as aggregate interlock that could lead to an enhanced vessel reserve strength and ductility
International Nuclear Information System (INIS)
Anderson, C.A.; Smith, P.D.
1979-01-01
Numerical prediction of the behavior of prestressed concrete reactor vessels (PCRVs) under static, dynamic and long term loadings is complicated by the currently ill-defined behavior of concrete under stress and the three-dimensional nature of PCRVs. Which constitutive model most closely approximates the behavior of concrete in PCRVs under load has not yet been decided. Many equations for accurately modeling the three-dimensional behavior of PCRVs tax the capability of a most up-to-date computing system. The main purpose of this paper is to compare the characteristics of two constitutive models which have been proposed for concrete, variable modulus cracking model and elastic-plastic model. Moreover, the behavior of typical concrete structures was compared, the materials of which obey these constitutive laws. The response to internal pressure of PCRV structure, the constitutive models for concrete, the test problems using a thick-walled concrete ring and a rectangular concrete plate, and the analysis of an axisymmetric concrete pressure vessel PV-26 using the variable modulus cracking model of the ADINA code are explained. The variable modulus cracking model can predict the behavior of reinforced concrete structures well into the range of nonlinear behavior. (Kako, I.)
Directory of Open Access Journals (Sweden)
Kwang Liang Koh
2017-07-01
Full Text Available This paper examines the effect of surface treatment and filler shape factor on the fracture toughness and elastic modulus of epoxy-based nanocomposite. Two forms of nanofillers, polydopamine-coated montmorillonite clay (D-clay and polydopamine-coated carbon nanofibres (D-CNF were investigated. It was found that Young’s modulus increases with increasing D-clay and D-CNF loading. However, the fracture toughness decreases with increased D-clay loading but increases with increased D-CNF loading. Explanations have been provided with the aid of fractographic analysis using electron microscope observations of the crack-filler interactions. Fractographic analysis suggests that although polydopamine provides a strong adhesion between the fillers and the matrix, leading to enhanced elastic stiffness, the enhancement prohibits energy release via secondary cracking, resulting in a decrease in fracture toughness. In contrast, 1D fibre is effective in increasing the energy dissipation during fracture through crack deflection, fibre debonding, fibre break, and pull-out.
Koh, Kwang Liang; Ji, Xianbai; Lu, Xuehong; Lau, Soo Khim; Chen, Zhong
2017-01-01
This paper examines the effect of surface treatment and filler shape factor on the fracture toughness and elastic modulus of epoxy-based nanocomposite. Two forms of nanofillers, polydopamine-coated montmorillonite clay (D-clay) and polydopamine-coated carbon nanofibres (D-CNF) were investigated. It was found that Young’s modulus increases with increasing D-clay and D-CNF loading. However, the fracture toughness decreases with increased D-clay loading but increases with increased D-CNF loading. Explanations have been provided with the aid of fractographic analysis using electron microscope observations of the crack-filler interactions. Fractographic analysis suggests that although polydopamine provides a strong adhesion between the fillers and the matrix, leading to enhanced elastic stiffness, the enhancement prohibits energy release via secondary cracking, resulting in a decrease in fracture toughness. In contrast, 1D fibre is effective in increasing the energy dissipation during fracture through crack deflection, fibre debonding, fibre break, and pull-out. PMID:28773136
Czech Academy of Sciences Publication Activity Database
Betekhtin, V. I.; Kolobov, Yu. R.; Golosova, O. A.; Dvořák, Jiří; Sklenička, Václav; Kardashev, B. K.; Kadomtsev, A. G.; Narykova, M. V.; Ivanov, M. B.
2016-01-01
Roč. 45, 1-2 (2016), s. 42-51 ISSN 1606-5131 Institutional support: RVO:68081723 Keywords : Creep * Elastic moduli * Plastic flow * Beta-type titanium alloys * Biomedical applications Subject RIV: JG - Metallurgy Impact factor: 2.500, year: 2016
Moriwaki, Takeshi; Oie, Tomonori; Takamizawa, Keiichi; Murayama, Yoshinobu; Fukuda, Toru; Omata, Sadao; Kanda, Keiichi; Nakayama, Yasuhide
2011-12-01
Variations in microscopic elastic structures along the entire length of canine aorta were evaluated by use of a scanning haptic microscope (SHM). The total aorta from the aortic arch to the abdominal aorta was divided into 6 approximately equal segments. After embedding the aorta in agar, it was cut into horizontal circumferential segments to obtain disk-like agar portions containing ring-like samples of aorta with flat surfaces (thickness, approximately 1 mm). The elastic modulus and topography of the samples under no-load conditions were simultaneously measured along the entire thickness of the wall by SHM by using a probe with a diameter of 5 μm and a spatial resolution of 2 μm at a rate of 0.3 s/point. The elastic modulus of the wall was the highest on the side of the luminal surface and decreased gradually toward the adventitial side. This tendency was similar to that of the change in the elastin fiber content. During the evaluation of the mid-portion of each tunica media segment, the highest elastic modulus (40.8 ± 3.5 kPa) was identified at the thoracic section of the aorta that had the highest density of elastic fibers. Under no-load conditions, portions of the aorta with high elastin density have a high elastic modulus.
Objectification of Modulus Elasticity of Foam Concrete Poroflow 17-5 on the Subbase Layer
Directory of Open Access Journals (Sweden)
Hájek Matej
2016-05-01
Full Text Available Principles of sustainable development create the need to develop new building materials. Foam concrete is a type of lightweight concrete that has many advantages compared to conventional building materials, for example low density and thermal insulation characteristics. With current development level, any negatively influencing material features are constantly eliminated as well. This paper is dealing with substitution of hydraulically bound mixtures by cement foam concrete Poroflow 17-5. The executed assessment is according to the methodology of assessing the existing asphalt pavements in Slovak Republic. The ex post calculation was used to estimate modulus range for Poroflow 17-5 based on the results of static load tests conducted using the Testing Experiment Equipment.
Sano, Hirotaka; Saijo, Yoshifumi; Kokubun, Shoichi
2006-01-01
The acoustic properties of rabbit supraspinatus tendon insertions were measured by scanning acoustic microscopy. After cutting parallel to the supraspinatus tendon fibers, specimens were fixed with 10% neutralized formalin, embedded in paraffin, and sectioned. Both the sound speed and the attenuation constant were measured at the insertion site. The 2-dimensional distribution of the sound speed and that of the attenuation constant were displayed with color-coded scales. The acoustic properties reflected both the histologic architecture and the collagen type. In the tendon proper and the non-mineralized fibrocartilage, the sound speed and attenuation constant gradually decreased as the predominant collagen type changed from I to II. In the mineralized fibrocartilage, they increased markedly with the mineralization of the fibrocartilaginous tissue. These results indicate that the non-mineralized fibrocartilage shows the lowest elastic modulus among 4 zones at the insertion site, which could be interpreted as an adaptation to various types of biomechanical stress.
Directory of Open Access Journals (Sweden)
Sen Yang
2018-01-01
Full Text Available This laboratory study investigated the damage evolution of sandstone specimens under two types of cyclic loading by monitoring and analyzing changes in the elastic moduli and the ultrasonic velocities during loading. During low-level cyclic loading, the stiffness degradation method was unable to describe the damage accumulations but the ultrasonic velocity measurements clearly reflected the damage development. A crack density parameter is introduced in order to interpret the changes in the tangential modulus and the ultrasonic velocities. The results show the following. (1 Low-level cyclic loading enhanced the anisotropy of the cracks. This results from the compression of intergranular clay minerals and fatigue failure. (2 Irreversible damage accumulations during cyclic loading with an increasing upper stress limit are the consequence of brittle failure in the sandstone’s microstructure.
Elastic modulus measurements of LDEF glasses and glass-ceramics using a speckle technique
International Nuclear Information System (INIS)
Wiedlocher, D.E.; Kinser, D.L.
1992-01-01
Elastic moduli of five glass types and the glass-ceramic Zerodur, exposed to a near-earth orbit environment on the Long Duration Exposure Facility (LDEF), were compared to that of unexposed samples. A double exposure speckle photography technique utilizing 633 nm laser light was used in the production of the speckle pattern. Subsequent illumination of a double exposed negative using the same wavelength radiation produces Young's fringes from which the in-plane displacements are measured. Stresses imposed by compressive loading produced measurable strains in the glasses and glass-ceramic
Didier, P; Piotrowski, B; Fischer, M; Laheurte, P
2017-05-01
The advent of new manufacturing technologies such as additive manufacturing deeply impacts the approach for the design of medical devices. It is now possible to design custom-made implants based on medical imaging, with complex anatomic shape, and to manufacture them. In this study, two geometrical configurations of implant devices are studied, standard and anatomical. The comparison highlights the drawbacks of the standard configuration, which requires specific forming by plastic strain in order to be adapted to the patient's morphology and induces stress field in bones without mechanical load in the implant. The influence of low elastic modulus of the materials on stress distribution is investigated. Two biocompatible alloys having the ability to be used with SLM additive manufacturing are considered, commercial Ti-6Al-4V and Ti-26Nb. It is shown that beyond the geometrical aspect, mechanical compatibility between implants and bones can be significantly improved with the modulus of Ti-26Nb implants compared with the Ti-6Al-4V. Copyright © 2016 Elsevier B.V. All rights reserved.
Directory of Open Access Journals (Sweden)
W. Pabst
2004-12-01
Full Text Available In this fourth paper of a series on the effective elastic properties of alumina-zirconia composite ceramics the influence of porosity on the effective tensile modulus of alumina and zirconia ceramics is discussed. The examples investigated are alumina and zirconia ceramics prepared from submicron powders by starch consolidation casting using two different types of starch, potato starch (median size D50 =47.2 µm and corn starch (median size D50 =13.7 µm. The dependence of effective tensile moduli E, on the porosity f, measured for porosities in the ranges of approx. 19-55 vol.% and 10-42 vol.% for alumina and zirconia, respectively, using a resonant frequency technique, was evaluated by fitting with various model relations, including newly developed ones. A detailed comparison of the fitting results suggests the superiority of the new relation E/E0 = (1 - f·(1 - f/fC, developed by the authors (with the tensile modulus of the dense ceramic material E0 and the critical porosity fC, over most other existing fit models. Only for special purposes and well-behaved data sets the recently proposed exponential relation E/E0 = exp [-Bf/(1 - f] and the well-known Phani-Niyogi relation E/E0 = (1 - f/fCN might be preferable.
International Nuclear Information System (INIS)
Ylivaara, Oili M.E.; Liu, Xuwen; Kilpi, Lauri; Lyytinen, Jussi; Schneider, Dieter; Laitinen, Mikko; Julin, Jaakko; Ali, Saima; Sintonen, Sakari; Berdova, Maria; Haimi, Eero; Sajavaara, Timo; Ronkainen, Helena; Lipsanen, Harri
2014-01-01
Use of atomic layer deposition (ALD) in microelectromechanical systems (MEMS) has increased as ALD enables conformal growth on 3-dimensional structures at relatively low temperatures. For MEMS device design and fabrication, the understanding of stress and mechanical properties such as elastic modulus, hardness and adhesion of thin film is crucial. In this work a comprehensive characterization of the stress, elastic modulus, hardness and adhesion of ALD aluminum oxide (Al 2 O 3 ) films grown at 110–300 °C from trimethylaluminum and water is presented. Film stress was analyzed by wafer curvature measurements, elastic modulus by nanoindentation and surface-acoustic wave measurements, hardness by nanoindentation and adhesion by microscratch test and scanning nanowear. The films were also analyzed by ellipsometry, optical reflectometry, X-ray reflectivity and time-of-flight elastic recoil detection for refractive index, thickness, density and impurities. The ALD Al 2 O 3 films were under tensile stress in the scale of hundreds of MPa. The magnitude of the stress decreased strongly with increasing ALD temperature. The stress was stable during storage in air. Elastic modulus and hardness of ALD Al 2 O 3 saturated to a fairly constant value for growth at 150 to 300 °C, while ALD at 110 °C gave softer films with lower modulus. ALD Al 2 O 3 films adhered strongly on cleaned silicon with SiO x termination. - Highlights: • The residual stress of Al 2 O 3 was tensile and stable during the storage in air. • Elastic modulus of Al 2 O 3 saturated to at 170 GPa for films grown at 150 to 300 °C. • At 110 °C Al 2 O 3 films were softer with high residual hydrogen and lower density. • The Al 2 O 3 adhered strongly on the SiO x -terminated silicon
Directory of Open Access Journals (Sweden)
Eva Wahyu Indriyati
2013-06-01
Full Text Available The increasing demand of crude oil will increase the price of petroleum asphalt. Indonesia has imported asphalt to meet the need for the annually road construction and maintenance. One solution to improving the rheological properties of bitumen is by adding the harder bitumen or other chemical compound to reduce dependence to petroleum asphalt. In Indonesia there is a source of natural asphalt in Buton Island, Sulawesi with huge amount of deposit that potentially could improve the rheological properties of Pen 60/70 Petroleum Asphalt. In order to obtain a better understanding on the contribution of Asbuton to the improvement of performance on rheological properties, this research used 19 variations of Asbuton and pen 60/70 petroleum bitumen. This variation is then subjected to the basic rheology test and the mechanistic test using Dynamic Shear Rheometer. The conclusion of basic rheological performance is obtained that mixture (Asbuton and 60/70 petroleum bitumen will increase hardness of bitumen. Conclusion on mechanistic rheological performance is that mixture (Asbuton and 60/70 petrol bitumen will increase Performance Grade (PG and Complex Shear Modulus (G*. The results from the analysis of Master Curve and Black Diagram, it is shown that the increasing proportion of bitumen Asbuton will decrease the phase angle (δ but its temperature susceptibility is worse.
Nonhomogeneous morphology and the elastic modulus of aligned carbon nanotube films
International Nuclear Information System (INIS)
Won, Yoonjin; Gao, Yuan; Kenny, Thomas W; Goodson, Kenneth E; Guzman de Villoria, Roberto; Wardle, Brian L; Xiang, Rong; Maruyama, Shigeo
2015-01-01
Carbon nanotube (CNT) arrays offer the potential to develop nanostructured materials that leverage their outstanding physical properties. Vertically aligned carbon nanotubes (VACNTs), also named CNT forests, CNT arrays, or CNT turfs, can provide high heat conductivity and sufficient mechanical compliance to accommodate thermal expansion mismatch for use as thermal interface materials (TIMs). This paper reports measurements of the in-plane moduli of vertically aligned, single-walled CNT (SWCNT) and multi-walled CNT (MWCNT) films. The mechanical response of these films is related to the nonhomogeneous morphology of the grown nanotubes, such as entangled nanotubes of a top crust layer, aligned CNTs in the middle region, and CNTs in the bottom layer. To investigate how the entanglements govern the overall mechanical moduli of CNT films, we remove the crust layer consisting of CNT entanglements by etching the CNT films from the top. A microfabricated cantilever technique shows that crust removal reduces the resulting moduli of the etched SWCNT films by as much as 40%, whereas the moduli of the etched MWCNT films do not change significantly, suggesting a minimal crust effect on the film modulus for thick MWCNT films (>90 μm). This improved understanding will allow us to engineer the mechanical moduli of CNT films for TIMs or packaging applications. (paper)
Nonhomogeneous morphology and the elastic modulus of aligned carbon nanotube films
Won, Yoonjin; Gao, Yuan; Guzman de Villoria, Roberto; Wardle, Brian L.; Xiang, Rong; Maruyama, Shigeo; Kenny, Thomas W.; Goodson, Kenneth E.
2015-11-01
Carbon nanotube (CNT) arrays offer the potential to develop nanostructured materials that leverage their outstanding physical properties. Vertically aligned carbon nanotubes (VACNTs), also named CNT forests, CNT arrays, or CNT turfs, can provide high heat conductivity and sufficient mechanical compliance to accommodate thermal expansion mismatch for use as thermal interface materials (TIMs). This paper reports measurements of the in-plane moduli of vertically aligned, single-walled CNT (SWCNT) and multi-walled CNT (MWCNT) films. The mechanical response of these films is related to the nonhomogeneous morphology of the grown nanotubes, such as entangled nanotubes of a top crust layer, aligned CNTs in the middle region, and CNTs in the bottom layer. To investigate how the entanglements govern the overall mechanical moduli of CNT films, we remove the crust layer consisting of CNT entanglements by etching the CNT films from the top. A microfabricated cantilever technique shows that crust removal reduces the resulting moduli of the etched SWCNT films by as much as 40%, whereas the moduli of the etched MWCNT films do not change significantly, suggesting a minimal crust effect on the film modulus for thick MWCNT films (>90 μm). This improved understanding will allow us to engineer the mechanical moduli of CNT films for TIMs or packaging applications.
International Nuclear Information System (INIS)
Zaragoza, J; Chang, A; Asuri, P
2017-01-01
Polymer hydrogelshave shown to exhibit improved properties upon the addition of nanoparticles; however, the mechanical underpinnings behind these enhancements have not been fully elucidated. Moreover, fewer studies have focused on developing an understanding of how polymer parameters affect the nanoparticle-mediated enhancements. In this study, we investigated the elastic properties of silica nanoparticle-reinforced poly(acrylamide) hydrogels synthesized using crosslinkers of various lengths. Crosslinker length positively affected the mechanical properties of hydrogels that were synthesized with or without nanoparticles. However the degree of nanoparticle enhancement was negatively correlated to crosslinker length. Our findings enable the understanding of the respective roles of nanoparticle and polymer properties on nanoparticle-mediated enhancement of hydrogels and thereby the development of next-generation nanocomposite materials. (paper)
Elasticity Modulus and Flexural Strength Assessment of Foam Concrete Layer of Poroflow
Hajek, Matej; Decky, Martin; Drusa, Marian; Orininová, Lucia; Scherfel, Walter
2016-10-01
Nowadays, it is necessary to develop new building materials, which are in accordance to the principles of the following provisions of the Roads Act: The design of road is a subject that follows national technical standards, technical regulations and objectively established results of research and development for road infrastructure. Foam concrete, as a type of lightweight concrete, offers advantages such as low bulk density, thermal insulation and disadvantages that will be reduced by future development. The contribution focuses on identifying the major material characteristics of foam concrete named Poroflow 17-5, in order to replace cement-bound granular mixtures. The experimental measurements performed on test specimens were the subject of diploma thesis in 2015 and continuously of the dissertation thesis and grant research project. At the beginning of the contribution, an overview of the current use of foam concrete abroad is elaborated. Moreover, it aims to determine the flexural strength of test specimens Poroflow 17-5 in combination with various basis weights of the underlying geotextile. Another part of the article is devoted to back-calculation of indicative design modulus of Poroflow based layers based on the results of static plate load tests provided at in situ experimental stand of Faculty of Civil Engineering, University of Žilina (FCE Uniza). Testing stand has been created in order to solve problems related to research of road and railway structures. Concern to building construction presents a physical homomorphic model that is identical with the corresponding theory in all structural features. Based on the achieved material characteristics, the tensile strength in bending of previously used road construction materials was compared with innovative alternative of foam concrete and the suitability for the base layers of pavement roads was determined.
DEFF Research Database (Denmark)
Asmussen, Erik; Peutzfeldt, Anne
2008-01-01
the restoration was left nonbonded. The resin composite was modelled with a modulus of elasticity of 5, 10, 15 or 20 GPa and loaded occlusally with 100 N. By means of the soft-ware program ABAQUS the von Mises stresses in enamel and dentin were calculated. RESULTS: In the bonded scenario, the maximum stresses...
DEFF Research Database (Denmark)
Pease, Bradley Justin; Michel, Alexander; Thybo, Anna Emilie A.
2012-01-01
A combined experimental and numerical approach for estimating the elastic modulus of reinforcement corrosion products is presented. Deformations between steel and mortar were measured using digital image correlation during accelerated corrosion testing at 100 μA/cm2 (~1.16 mm/year). Measured defo...
Zheng, Kunpeng; Lukovic, M.; De Schutter, Geert; Ye, G.; Taerwe, Luc
2016-01-01
This work aims at providing a better understanding of the mechanical properties of the reaction rim in the alkali-silica reaction. The elastic modulus of the calcium alkali silicate constituting the reaction rim, which is formed at the interface between alkali silicate and Ca(OH)2 in a
International Nuclear Information System (INIS)
Kharmanda, G.
2015-01-01
Highlights: • We develop a new formulation between the yield stress and Young’s modulus of bone. • We validate the optimized formulation for cortical and trabecular bone. • We integrate the reliability analysis into artificially hip replacement design. - Abstract: Using classical design optimization methods for implant-bone studies does not completely guarantee a safety and satisfactory performance, due in part to the randomness of bone properties and loading. Here, the material properties of the different bone layers are considered as uncertain parameters. So their corresponding yield stress values will not be deterministic, that leads to integrate variable limitations into the optimization process. Here there is a strong need to find a reliable mathematical relationship between yield stress and material properties of the different bone layers. In this work, a new optimized formulation for yield stress against elasticity modulus relationship is first developed. This model is based on some experimental results. A validation of the proposed formulation is next carried out to show its accuracy for both bone layers (cortical and cancellous). A probabilistic sensitivity analysis is then carried out to show the role of each input parameter with respect to the limit state function. The new optimized formulation is next integrated into a reliability analysis problem in order to assess the reliability level of the stem–bone study where we deal with variable boundary limitations. An illustrative application is considered as a bi-dimensional example (contains only two variables) in order to present the results in an illustrative 2D space. Finally, a multi-variable problem considering several daily loading cases on a hip prosthesis shows the applicability of the proposed strategy
Soares, Priscilla Barbosa Ferreira; Nunes, Sarah Arantes; Franco, Sinésio Domingues; Pires, Raphael Rezende; Zanetta-Barbosa, Darceny; Soares, Carlos José
2014-01-01
The clinical performance of dental implants is strongly defined by biomechanical principles. The aim of this study was to quantify the Vicker's hardness (VHN) and elastic modulus (E) surround bone to dental implant in different regions, and to discuss the parameters of dynamic microindantion test. Ten cylindrical implants with morse taper interface (Titamax CM, Neodent; 3.5 mm diameter and 7 mm a height) were inserted in rabbit tibia. The mechanical properties were analyzed using microhardness dynamic indenter with 200 mN load and 15 s penetration time. Seven continuous indentations were made distancing 0.08 mm between each other perpendicularly to the implant-bone interface towards the external surface, at the limit of low (Lp) and high implant profile (Hp). Data were analyzed by Student's t-test (a=0.05) to compare the E and VHN values obtained on both regions. Mean and standard deviation of E (GPa) were: Lp. 16.6 ± 1.7, Hp. 17.0 ± 2.5 and VHN (N/mm2): Lp. 12.6 ± 40.8, Hp. 120.1 ± 43.7. No statistical difference was found between bone mechanical properties of high and low profile of the surround bone to implant, demonstrating that the bone characterization homogeneously is pertinent. Dynamic microindantion method proved to be highly useful in the characterization of the individual peri-implant bone tissue.
Bosch, C A
1971-04-23
The chief conclusion to be drawn from the results of this study is that redwoods are amazingly vigorous. The results support both the lumber companies and the conservationists. There is no question that old growth giant redwoods must be preserved. Only commercial greed could be a basis for refuting that stand. On the other hand, the lumber companies seem to be supported in their contention that redwoods can be farmed without driving them to extinction. The central issue revolves around the old trees. And here profit is the big factor. Lumbering is an important industry in California, and redwood lumbering represents about 20 percent of the industry (l). Most of the big names in timber, such as Weyerhaeuser and Georgia-Pacific, are involved in logging the California redwood. At the current rate of logging, particularly of old growth stands, the Bank of America estimates that employment in Humboldt County will be down significantly by 1975 (4). It has been argued that tourism would more than compensate for the lower employment in logging. But not if the trees that the tourists come to see are gone. Why can't young and mature trees be harvested at a reasonable rate, the old trees saved, and both tourism and logging flourish? The question posed earlier has been answered. Redwood growth and survival can be modeled, using matrix methods in a new context. Meaningful conclusions may be drawn. And the results are sufficiently tantalizing to inspire further research.
Arnold, W.; Faber, C.; Knapmeyer, M.; Witte, L.; Schröder, S.; Tune, J.; Möhlmann, D.; Roll, R.; Chares, B.; Fischer, H.; Seidensticker, K.
2014-07-01
The landing of Philae on comet 67P/Churyumov-Gerasimenko is scheduled for November 11, 2014. Each of the three landing feet of Philae house a triaxial acceleration sensor of CASSE, which will thus be the first sensors to be in mechanical contact with the cometary surface. CASSE will be in listening mode to record the deceleration of the lander, when it impacts with the comet at a velocity of approx. 0.5 m/s. The analysis of this data yields information on the reduced elastic modulus and the yield stress of the comet's surface material. We describe a series of controlled landings of a lander model. The tests were conducted in the Landing & Mobility Test Facility (LAMA) of the DLR Institute of Space Systems in Bremen, Germany, where an industrial robot can be programmed to move landers or rovers along predefined paths, allowing to adapt landing procedures with predefined velocities. The qualification model of the Philae landing gear was used in the tests. It consists of three legs manufactured of carbon fiber and metal joints. A dead mass of the size and mass of the lander housing is attached via a damper above the landing gear to represent the lander structure as a whole. Attached to each leg is a foot with two soles and a mechanically driven fixation screw (''ice screw'') to secure the lander on the comet. The right soles, if viewed from the outside towards the lander body, house a Brüel & Kjaer DeltaTron 4506 triaxial piezoelectric accelerometer as used on the spacecraft. Orientation of the three axes was such that one of the axes, here the X-axis of the accelerometer, points downwards, while the Y- and Z-axes are horizontal. Data were recorded at a sampling rate of 8.2 kHz within a time gate of 2 s. In parallel, a video sequence was taken, in order to monitor the touchdown on the sand and the movement of the ice screws. Touchdown measurements were conducted on three types of ground with landing velocities between 0.1 to 1.1 m/s. Landings with low velocities were
Giddings, V L; Kurtz, S M; Jewett, C W; Foulds, J R; Edidin, A A
2001-07-01
Polymethylmethacrylate (PMMA) bone cement is used in total joint replacements to anchor implants to the underlying bone. Establishing and maintaining the integrity of bone cement is thus of critical importance to the long-term outcome of joint replacement surgery. The goal of the present study was to evaluate the suitability of a novel testing technique, the small punch or miniaturized disk bend test, to characterize the elastic modulus and fracture behavior of PMMA. We investigated the hypothesis that the crack initiation behavior of PMMA during the small punch test was sensitive to the test temperature. Miniature disk-shaped specimens, 0.5 mm thick and 6.4 mm in diameter, were prepared from PMMA and Simplex-P bone cement according to manufacturers' instructions. Testing was conducted at ambient and body temperatures, and the effect of test temperature on the elastic modulus and fracture behavior was statistically evaluated using analysis of variance. For both PMMA materials, the test temperature had a significant effect on elastic modulus and crack initiation behavior. At body temperature, the specimens exhibited "ductile" crack initiation, whereas at room temperature "brittle" crack initiation was observed. The small punch test was found to be a sensitive and repeatable test method for evaluating the mechanical behavior of PMMA. In light of the results of this study, future small punch testing should be conducted at body temperature.
Hojo, M.; Matsuoka, T.; Hashimoto, M.; Tanaka, M.; Sugano, M.; Ochiai, S.; Miyashita, K.
2006-10-01
Young's modulus of Nb3Sn filaments in Nb3Sn/Cu superconducting composite wire was investigated in detail. Nb3Sn filaments were first extracted from composite wire. Nitric acid and hydrofluoric acid were used to remove copper stabilizer, Nb3Sn/Nb barrier and bronze. Then, Nb3Sn filaments were impregnated with epoxy resin to form simple filament bundle composite rods. A large difference in Young's moduli of filaments and epoxy resin enhance the accuracy of the measurement of Nb3Sn filament modulus. The ratio of Nb3Sn to Nb in filaments and the number of filaments in the fiber bundle composite rods were used in the final calculation of the Young's modulus of Nb3Sn. The obtained modulus of 127 GPa was the lower bound of the already reported values.
International Nuclear Information System (INIS)
Hojo, M.; Matsuoka, T.; Hashimoto, M.; Tanaka, M.; Sugano, M.; Ochiai, S.; Miyashita, K.
2006-01-01
Young's modulus of Nb 3 Sn filaments in Nb 3 Sn/Cu superconducting composite wire was investigated in detail. Nb 3 Sn filaments were first extracted from composite wire. Nitric acid and hydrofluoric acid were used to remove copper stabilizer, Nb 3 Sn/Nb barrier and bronze. Then, Nb 3 Sn filaments were impregnated with epoxy resin to form simple filament bundle composite rods. A large difference in Young's moduli of filaments and epoxy resin enhance the accuracy of the measurement of Nb 3 Sn filament modulus. The ratio of Nb 3 Sn to Nb in filaments and the number of filaments in the fiber bundle composite rods were used in the final calculation of the Young's modulus of Nb 3 Sn. The obtained modulus of 127 GPa was the lower bound of the already reported values
International Nuclear Information System (INIS)
Emmerich, F.G.
1987-01-01
A microscopic model (granular model) is presented to study heat treated carbons. A granular structure is defined in the carbon matrix, composed of turbostratic graphite-like microcrystallites, cross-linkings and micropores. A general expression is developed to calculate the volume fraction X of the conducting phase of the granular structure as a function of structural parameters obtained from X-ray diffraction small angle X-ray scattering. The granular model and the percolation theory are used to explain the electrical resistivity behaviour with the heat treatment temperature (HTT), where X is the fundamental parameter. An electron spin resonance (ESR) study of the low and high HTT ranges is presented, including the transition range (700-1300 0 C). The elucitation of the spin center nature in this range and the liking with the two adjacent ranges has been pursued. An expression to calculate the elastic modulus (Young's modulus), based on the microscopic granular model with the fundamental participation of the cross-linkings, is derived to account for the behavior of the modulus with the HTT. The granular model with the expression of X, the percolation-resistivity theory, the ESR study, and the expression of the elastic modulus are applied to the babassu endocarp carbon heat treated up to 2200 0 C. This material can be classified as a tipical non-graphitic carbon, being useful to search the validity of the model and the proposed expressions. It is observed that the theoretical expressions describe with reasonable accuracy the respective experimental behaviours. The measurements of physical and chemical parameters of the babassu endocarp treated up to 2200 0 C area also included. (author) [pt
Sekiguchi, Atsushi
2013-03-01
The QCM method allows measurements of impedance, an index of swelling layer viscosity in a photoresist during development. While impedance is sometimes used as a qualitative index of change in the viscosity of the swelling layer, it has to date not been used quantitatively, for data analysis. We explored a method for converting impedance values to elastic modulus (Pa), a coefficient expressing viscosity. Applying this method, we compared changes in the viscosity of the swelling layer in an ArF resist generated during development in a TMAH developing solution and in a TBAH developing solution. This paper reports the results of this comparative study.
International Nuclear Information System (INIS)
Stachiv, Ivo; Kuo, Chih-Yun; Fang, Te-Hua; Mortet, Vincent
2016-01-01
Measurement of ultrathin film thickness and its basic properties can be highly challenging and time consuming due to necessity of using several very sophisticated devices. Here, we report an easy accessible resonant based method capable to simultaneously determinate the residual stress, elastic modulus, density and thickness of ultrathin film coated on doubly clamped micro-/nanobeam. We show that a general dependency of the resonant frequencies on the axial load is also valid for in-plane vibrations, and the one depends only on the considered vibrational mode. As a result, we found that the film elastic modulus, density and thickness can be evaluated from two measured in-plane and out-plane fundamental resonant frequencies of micro-/nanobeam with and without film under different prestress forces. Whereas, the residual stress can be determined from two out-plane (in-plane) measured consecutive resonant frequencies of beam with film under different prestress forces without necessity of knowing film and substrate properties and dimensions. Moreover, we also reveal that the common uncertainties in force (and thickness) determination have a negligible (and minor) impact on the determined film properties. The application potential of the present method is illustrated on the beam made of silicon and SiO_2 with deposited 20 nm thick AlN and 40 nm thick Au thin films, respectively.
Elastic modulus of Al-Si/SiC metal matrix composites as a function of volume fraction
Energy Technology Data Exchange (ETDEWEB)
Santhosh Kumar, S; Rajasekharan, T [Powder Metallurgy Group, Defence Metallurgical Research Laboratory, Kanchanbagh PO, Hyderabad-500 058 (India); Seshu Bai, V [School of Physics, University of Hyderabad, Central University PO, Hyderabad-500 046 (India); Rajkumar, K V; Sharma, G K; Jayakumar, T, E-mail: dearsanthosh@gmail.co [Non-Destructive Evaluation Division, Indira Gandhi Center for Atomic Research, Kalpakkam, Chennai-603 102 (India)
2009-09-07
Aluminum alloy matrix composites have emerged as candidate materials for electronic packaging applications in the field of aerospace semiconductor electronics. Composites prepared by the pressureless infiltration technique with high volume fractions in the range 0.41-0.70 were studied using ultrasonic velocity measurements. For different volume fractions of SiC, the longitudinal velocity and shear velocity were found to be in the range of 7600-9300 m s{sup -1} and 4400-5500 m s{sup -1}, respectively. The elastic moduli of the composites were determined from ultrasonic velocities and were analysed as a function of the volume fraction of the reinforcement. The observed variation is discussed in the context of existing theoretical models for the effective elastic moduli of two-phase systems.
Directory of Open Access Journals (Sweden)
Adham El-Newihy
2018-02-01
Full Text Available This study aims to evaluate self-healing properties and recovered dynamic moduli of engineered polypropylene fiber reinforced concrete using non-destructive resonant frequency testing. Two types of polypropylene fibers (0.3% micro and 0.6% macro and two curing conditions have been investigated: Water curing (at ~25 Celsius and air curing. The Impact Resonance Method (IRM has been conducted in both transverse and longitudinal modes on concrete cylinders prior/post crack induction and post healing of cracks. Specimens were pre-cracked at 14 days, obtaining values of crack width in the range of 0.10–0.50 mm. Addition of polypropylene fibers improved the dynamic response of concrete post-cracking by maintaining a fraction of the original resonant frequency and elastic properties. Macro fibers showed better improvement in crack bridging while micro fiber showed a significant recovery of the elastic properties. The results also indicated that air-cured Polypropylene Fiber Reinforced Concrete (PFRC cylinders produced ~300 Hz lower resonant frequencies when compared to water-cured cylinders. The analyses showed that those specimens with micro fibers exhibited a higher recovery of dynamic elastic moduli.
Directory of Open Access Journals (Sweden)
Md Azree Othuman Mydin
2012-09-01
Full Text Available This paper focused on an experimental works that have been performed to examine the young’s modulus of foamed concrete at elevated temperatures up to 600°C. Foamed concrete of 650 and 1000 kg/m3 density were cast and tested under compression and bending. The experimental results of this study consistently demonstrated that the loss in stiffness for cement based material like foamed concrete at elevated temperatures occurs predominantly after about 95°C, regardless of density. This indicates that the primary mechanism causing stiffness degradation is microcracking, which occurs as water expands and evaporates from the porous body. As expected, reducing the density of LFC reduces its strength and stiffness. However, for LFC of different densities, the normalised strength-temperature and stiffness-temperature relationships are very similar.
International Nuclear Information System (INIS)
Aschl, H.; Stoeckl, S.
1981-01-01
At the Institut fuer Massivbau of the Technical University of Munich testing machines were built, which allow to test sealed and unsealed cylinders with uniaxial stress state at elevated temperatures till 523 K (250 0 C). With this equipment tests were carried out at predried, unsealed and sealed specimens to study - thermal expansion coefficient - modulus of elasticity - shrinkage and - creep of concrete at elevated temperatures of 353 K (80 0 C) and 393 K (120 0 C) and at a normal temperature of 293 K (20 0 C). In addition the residual strength of all specimens was measured. In the worst case (unsealed, i.e. drying specimens) some showed a maximum decrease in strength up to 60%. (orig.) [de
Directory of Open Access Journals (Sweden)
Mojzeš Marcel
2015-03-01
Full Text Available The Gabčíkovo hydroelectric power plant is located in a complicated geological environment (gravel sub-soil and a high groundwater level. Excavation work started after the withdrawal of water in the autumn of 1984 and lasted until the autumn of 1986. A basic geodetic control network with a special monument was founded before the excavation work began. This network served for the setting-out of the hydroelectric power plant as well as for the control of the excavation work. The repeated geodetic control measurements have been evaluated and presented at many seminars and conferences. Monitoring the horizontal and vertical stability of the geodetic control network during the general site excavation showed significant horizontal and vertical deformations. The paper is focused on an estimation of an effective Young's modulus of elasticity in the area studied.
Energy Technology Data Exchange (ETDEWEB)
Meza, J. M.; Franco, E. E.; Farias, M. C. M.; Buiochi, F.; Souza, R. M.; Cruz, J.
2008-07-01
Currently, the acoustic and nano indentation techniques are two of the most used techniques for materials elastic modulus measurement. In this article fundamental principles and limitations of both techniques are shown and discussed. Last advances in nano indentation technique are also reviewed. an experimental study in ceramic, metallic, composite and single crystals was also done. Results shown that ultrasonic technique is capable to provide results in agreement with those reported in literature. However, ultrasonic technique does not allow measuring the elastic modulus of some small samples and single crystals. On the other hand, the nano indentation technique estimates the elastic modulus values in reasonable agreement with those measured by acoustic methods, particularly in amorphous materials, while in some policristaline materials some deviation from expected values was obtained. (Author) 29 refs.
Directory of Open Access Journals (Sweden)
Esther Merlo
2014-04-01
Full Text Available Aim of study: Modelling the structural quality of Pinus pinaster Ait. wood on the basis of measurements made on standing trees is essential because of the importance of the species in the Galician forestry and timber industries and the good mechanical properties of its wood. In this study, we investigated how timber stiffness is affected by tree and stand properties, climatic and edaphic characteristics and competition. Area of study: The study was performed in Galicia, north-western Spain.Material and methods: Ten pure and even-aged P. pinaster stands were selected and tree and stand variables and the stress wave velocity of 410 standing trees were measured. A sub-sample of 73 trees, representing the variability in acoustic velocity, were felled and sawed into structural timber pieces (224 which were subjected to a bending test to determine the modulus of elasticity (MOE. Main results: Linear models including wood properties explained more than 97%, 73% and 60% of the observed MOE variability at site, tree and board level, respectively, with acoustic velocity and wood density as the main regressors. Other linear models, which did not include wood density, explained more than 88%, 69% and 55% of the observed MOE variability at site, tree and board level, respectively, with acoustic velocity as the main regressor. Moreover, a classification tree for estimating the visual grade according to standard UNE 56544:2011 was developed. Research highlights: The results have demonstrated the usefulness of acoustic velocity for predicting MOE in standing trees. The use of the fitted equations together with existing dynamic growth models will enable preliminary assessment of timber stiffness in relation to different silvicultural alternatives used with this species.Keywords: stress wave velocity, modulus of elasticity, site index, competition index, stepwise regression, CART.
Energy Technology Data Exchange (ETDEWEB)
Lavery, N.P., E-mail: N.P.Lavery@swansea.ac.uk [Materials Research Centre, College of Engineering, Swansea University Bay Campus, Fabian Way, Swansea SA1 8EP (United Kingdom); Zienkiewicz Centre for Computational Engineering, College of Engineering, Swansea University Bay Campus, Fabian Way, Swansea SA1 8EP (United Kingdom); Cherry, J.; Mehmood, S. [Materials Research Centre, College of Engineering, Swansea University Bay Campus, Fabian Way, Swansea SA1 8EP (United Kingdom); Zienkiewicz Centre for Computational Engineering, College of Engineering, Swansea University Bay Campus, Fabian Way, Swansea SA1 8EP (United Kingdom); Davies, H. [Materials Research Centre, College of Engineering, Swansea University Bay Campus, Fabian Way, Swansea SA1 8EP (United Kingdom); Girling, B.; Sackett, E. [Materials Research Centre, College of Engineering, Swansea University Bay Campus, Fabian Way, Swansea SA1 8EP (United Kingdom); Zienkiewicz Centre for Computational Engineering, College of Engineering, Swansea University Bay Campus, Fabian Way, Swansea SA1 8EP (United Kingdom); Brown, S.G.R. [Materials Research Centre, College of Engineering, Swansea University Bay Campus, Fabian Way, Swansea SA1 8EP (United Kingdom); Sienz, J. [Zienkiewicz Centre for Computational Engineering, College of Engineering, Swansea University Bay Campus, Fabian Way, Swansea SA1 8EP (United Kingdom)
2017-05-02
The microstructure and mechanical properties of 316L steel have been examined for parts built by a powder bed laser fusion process, which uses a laser to melt and build parts additively on a layer by layer basis. Relative density and porosity determined using various experimental techniques were correlated against laser energy density. Based on porosity sizes, morphology and distributions, the porosity was seen to transition between an irregular, highly directional porosity at the low laser energy density and a smaller, more rounded and randomly distributed porosity at higher laser energy density, thought to be caused by keyhole melting. In both cases, the porosity was reduced by hot isostatic pressing (HIP). High throughput ultrasound based measurements were used to calculate elasticity properties and show that the lower porosities from builds with higher energy densities have higher elasticity moduli in accordance with empirical relationships, and hot isostatic pressing improves the elasticity properties to levels associated with wrought/rolled 316L. However, even with hot isostatic pressing the best properties were obtained from samples with the lowest porosity in the as-built condition. A finite element stress analysis based on the porosity microstructures was undertaken, to understand the effect of pore size distributions and morphology on the Young's modulus. Over 1–5% porosity range angular porosity was found to reduce the Young's modulus by 5% more than rounded porosity. Experimentally measured Young's moduli for samples treated by HIP were closer to the rounded trends than the as-built samples, which were closer to angular trends. Tensile tests on specimens produced at optimised machine parameters displayed a high degree of anisotropy in the build direction and test variability for as-built parts, especially between vertical and horizontal build directions. The as-built properties were generally found to have a higher yield stress, but
International Nuclear Information System (INIS)
Lavery, N.P.; Cherry, J.; Mehmood, S.; Davies, H.; Girling, B.; Sackett, E.; Brown, S.G.R.; Sienz, J.
2017-01-01
The microstructure and mechanical properties of 316L steel have been examined for parts built by a powder bed laser fusion process, which uses a laser to melt and build parts additively on a layer by layer basis. Relative density and porosity determined using various experimental techniques were correlated against laser energy density. Based on porosity sizes, morphology and distributions, the porosity was seen to transition between an irregular, highly directional porosity at the low laser energy density and a smaller, more rounded and randomly distributed porosity at higher laser energy density, thought to be caused by keyhole melting. In both cases, the porosity was reduced by hot isostatic pressing (HIP). High throughput ultrasound based measurements were used to calculate elasticity properties and show that the lower porosities from builds with higher energy densities have higher elasticity moduli in accordance with empirical relationships, and hot isostatic pressing improves the elasticity properties to levels associated with wrought/rolled 316L. However, even with hot isostatic pressing the best properties were obtained from samples with the lowest porosity in the as-built condition. A finite element stress analysis based on the porosity microstructures was undertaken, to understand the effect of pore size distributions and morphology on the Young's modulus. Over 1–5% porosity range angular porosity was found to reduce the Young's modulus by 5% more than rounded porosity. Experimentally measured Young's moduli for samples treated by HIP were closer to the rounded trends than the as-built samples, which were closer to angular trends. Tensile tests on specimens produced at optimised machine parameters displayed a high degree of anisotropy in the build direction and test variability for as-built parts, especially between vertical and horizontal build directions. The as-built properties were generally found to have a higher yield stress, but lower upper
Energy Technology Data Exchange (ETDEWEB)
Tiriolo, Raffaele [Department of Medical and Surgical Sciences, University Magna Graecia of Catanzaro, Viale Europa 88100 Catanzaro Italy; Rangnekar, Neel [Department of Chemical Engineering and Materials Science, University of Minnesota, 421 Washington Ave SE Minneapolis MN 55455 USA; Zhang, Han [Department of Chemical Engineering and Materials Science, University of Minnesota, 421 Washington Ave SE Minneapolis MN 55455 USA; Shete, Meera [Department of Chemical Engineering and Materials Science, University of Minnesota, 421 Washington Ave SE Minneapolis MN 55455 USA; Bai, Peng [Department of Chemistry and Chemistry Theory Center, University of Minnesota, 207 Pleasant St SE Minneapolis MN 55455 USA; Nelson, John [Characterization Facility, University of Minnesota, 12 Shepherd Labs, 100 Union St. S.E. Minneapolis MN 55455 USA; Karapetrova, Evguenia [Surface Scattering and Microdiffraction, X-ray Science Division, Argonne National Laboratory, 9700 S. Cass Ave, Building 438-D002 Argonne IL 60439 USA; Macosko, Christopher W. [Department of Chemical Engineering and Materials Science, University of Minnesota, 421 Washington Ave SE Minneapolis MN 55455 USA; Siepmann, Joern Ilja [Department of Chemistry and Chemistry Theory Center, University of Minnesota, 207 Pleasant St SE Minneapolis MN 55455 USA; Lamanna, Ernesto [Department of Health Sciences, University Magna Graecia of Catanzaro, Viale Europa 88100 Catanzaro Italy; Lavano, Angelo [Department of Medical and Surgical Sciences, University Magna Graecia of Catanzaro, Viale Europa 88100 Catanzaro Italy; Tsapatsis, Michael [Department of Chemical Engineering and Materials Science, University of Minnesota, 421 Washington Ave SE Minneapolis MN 55455 USA
2017-05-08
A low-temperature synthesis coupled with mild activation produces zeolite films exhibiting low dielectric constant (low-k) matching the theoretically predicted and experimentally measured values for single crystals. This synthesis and activation method allows for the fabrication of a device consisting of a b-oriented film of the pure-silica zeolite MFI (silicalite-1) supported on a gold-coated silicon wafer. The zeolite seeds are assembled by a manual assembly process and subjected to optimized secondary growth conditions that do not cause corrosion of the gold underlayer, while strongly promoting in-plane growth. The traditional calcination process is replaced with a non-thermal photochemical activation to ensure preservation of an intact gold layer. The dielectric constant (k), obtained through measurement of electrical capacitance in a metal-insulator-metal configuration, highlights the ultralow k approximate to 1.7 of the synthetized films, which is among the lowest values reported for an MFI film. There is large improvement in elastic modulus of the film (E approximate to 54 GPa) over previous reports, potentially allowing for integration into silicon wafer processing technology.
Zhou, Jihan; Liang, Dehai; Contera, Sonia
2015-10-01
Penetration and partition of C60 to the lipid bilayer core are both relevant to C60 toxicity, and useful to realise C60 biomedical potential. A key aspect is the effect of C60 on bilayer mechanical properties. Here, we present an experimental study on the mechanical effect of the incorporation of C60 into the hydrophobic core of fluid and gel phase zwitterionic phosphatidylcholine (PC) lipid bilayers. We demonstrate its incorporation inside the hydrophobic lipid core and the effect on the packing of the lipids and the vesicle size using a combination of infrared (IR) spectroscopy, atomic force microscopy (AFM) and laser light scattering. Using AFM we measured the Young's modulus of elasticity (E) of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC), 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) and 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC) in the absence (presence) of intra-membranous C60 at 24.5 °C. E of fluid phase supported bilayers is not altered by C60, but E increases with incorporation of C60 in gel phase bilayers. The increase is higher for longer hydrocarbon chains: 1.6 times for DPPC and 2 times for DSPC. However the mechanical resistance of gel phase bilayers of curved bilayered structures decreases with the incorporation of C60. Our combined results indicate that C60 causes a decrease in gel phase lipid mobility, i.e. an increase in membrane viscosity.
Directory of Open Access Journals (Sweden)
André Luis Christoforo
2013-04-01
Full Text Available Este trabalhou objetiva apresentar uma metodologia analítica para o cálculo dos módulos de elasticidade longitudinal (E e transversal (G em vigas de madeira de dimensões estruturais, segundo o emprego das teorias de vigas de Euler Bernoulli e Timoshenko, sendo utilizado o ensaio de flexão estática a três pontos. As madeiras testadas foram o Pinus elliottii e a Corymbia citriodora. Os resultados encontrados relevaram ser o módulo de elasticidade longitudinal 18,70 vezes superior ao módulo transversal do Pinus elliottii e 21,2 superior ao módulo transversal do Corymbia citriodora, sendo estes compatíveis quando comparada a relação entre E e G estabelecida pela norma Brasileira ABNT NBR 7190:1997 (Projeto de Estruturas de Madeira, que define ser o módulo de elasticidade longitudinal vinte vezes superior ao transversal.This paper proposed a test method to obtain the shear (G and longitudinal (E modulus of elasticity in timber beams with structural dimensions, based on the static three-points bending tests and the Euler Bernoulli and Timoshenko beams theories. The woods tested were the Corymbia citriodora and Pinus elliottii. The results revealed that the longitudinal modulus of elasticity of Pinus elliottii is 18.70 greater than the shear modulus, and 21.16 greater than the shear modulus of Corymbia citriodora, being consistent this results when compared to the proposed by the Brazilian standard ABNT NBR 7190:1997 (Design of Wood Structures, being the longitudinal modulus of elasticity twenty times greater than the shear modulus.
Directory of Open Access Journals (Sweden)
Pereira, A. H. A.
2012-06-01
Full Text Available The work herein verifies the changes of the elastic moduli, damping and modulus of rupture (MOR of a high alumina refractory castable due to heating, cooling and heating-cooling thermal shock damage. Twelve prismatic specimens were prepared for the tests and divided into four groups. The thermal shocks were performed on three groups, each containing three specimens having abrupt temperature changes of 1100°C during heating in the first group, during cooling in the second and during heating followed by cooling in the third group. The fourth group, which was taken as a reference did not receive any thermal shock. The elastic moduli were measured after each thermal shock cycle. After 10 cycles, the MOR, the damping and the damping dependence on excitation amplitude were measured at room temperature for all specimens.
The elastic moduli showed a similar decrease and the damping a similar increase due to the cooling and heating-cooling thermal shocks. The heating thermal shocks caused no significant changes on the elastic moduli and damping. However, the MOR appeared to be sensitive to the heating thermal shock. This work also shows that the damping for the studied refractory castable is non-linear (i.e., amplitude of excitation sensitive and that this non-linearity increases when the damage level rises.
En este trabajo se investigaron las alteraciones de los módulos elásticos dinámicos, del amortiguamiento y del módulo de rotura (MOR de un material refractario moldeable de alta alúmina después de recibir choques térmicos de calentamiento, enfriamiento y calentamiento seguido de enfriamiento (calentamiento-enfriamiento. Para ello se prepararon doce cuerpos prismáticos dividiéndolos en cuatro grupos. Los choques térmicos se le aplicaron a sólo tres grupos, cada uno con tres muestras. Al primer grupo se le aplicó un cambio brusco de temperatura de 1100 °C en calentamiento, en enfriamiento al segundo grupo y calentamiento seguido
Elastic modulus, hardness and fracture behavior of Pb(Zn1/3Nb2/3)O3-PbTiO3 single crystal
International Nuclear Information System (INIS)
Zeng Kaiyang; Pang Yongsong; Shen Lu; Rajan, K.K.; Lim, Leong-Chew
2008-01-01
The deformation, crack initiation, fracture behavior and mechanical properties of (0 0 1)-oriented single crystal of Pb(Zn 1/3 Nb 2/3 )O 3 -7% PbTiO 3 (PZN-7% PT) in both unpoled and poled states have been investigated by using nanoindentation, micro-indentation and three-point bending experiments. Nanoindentation experiments revealed that, unlike typical brittle materials, material pile-ups around the indentation impressions were commonly observed at ultra-low loads. The elastic modulus and hardness were also determined by using nanoindentation experiments. The critical indentation load for crack initiation, determined by using micro-indentation experiments, is 0.135 N for unpoled samples, increasing to 0.465 N for the positive surface (crack propagation direction against the poling direction) of poled samples but decreasing slightly to 0.132 N for the negative surface (crack propagation direction along the poling direction) of the poled samples. Indentation/strength (three-point bend) test showed a similar trend for the 'apparent' fracture toughness, giving 0.36 MPa√m for unpoled samples, increasing to 0.44 MPa√m for the positive surface of poled samples but decreasing to 0.30 MPa√m for the negative surface of poled samples. Polarized light microscopy and scanning electron microscopy were used to study the material adjacent to the indentations and the fracture surfaces produced by the three-point bend tests. The results were correlated with the various fracture properties observed
Kesteven, Jazmin; Kannan, M Bobby; Walter, Rhys; Khakbaz, Hadis; Choe, Han-Choel
2015-01-01
In this study, the in vitro degradation behaviour of titanium-tantalum (Ti-Ta) alloys (10-30 wt.% Ta) was investigated and compared with conventional implant materials, i.e., commercially pure titanium (Cp-Ti) and titanium-aluminium-vanadium (Ti6Al4V) alloy. Among the three Ti-Ta alloys studied, the Ti20Ta (6.3×10(-4) mm/y) exhibited the lowest degradation rate, followed by Ti30Ta (1.2×10(-3) mm/y) and Ti10Ta (1.4×10(-3) mm/y). All the Ti-Ta alloys exhibited lower degradation rate than that of Cp-Ti (1.8×10(-3) mm/y), which suggests that Ta addition to Ti is beneficial. As compared to Ti6Al4V alloy (8.1×10(-4) mm/y), the degradation rate of Ti20Ta alloy was lower by ~22%. However, the Ti30Ta alloy, which has closer elastic modulus to that of natural bone, showed ~48% higher degradation rate than that of Ti6Al4V alloy. Hence, to improve the degradation performance of Ti30Ta alloy, an intermediate thin porous layer was formed electrochemically on the alloy followed by calcium phosphate (CaP) electrodeposition. The coated Ti30Ta alloy (3.8×10(-3) mm/y) showed ~53% lower degradation rate than that of Ti6Al4V alloy. Thus, the study suggests that CaP coated Ti30Ta alloy can be a viable material for load-bearing permanent implants. Copyright © 2014 Elsevier B.V. All rights reserved.
Energy Technology Data Exchange (ETDEWEB)
Kesteven, Jazmin [Biomaterials and Engineering Materials (BEM) Laboratory, School of Engineering and Physical Sciences, James Cook University, Townsville, Queensland 4811 (Australia); Kannan, M. Bobby, E-mail: bobby.mathan@jcu.edu.au [Biomaterials and Engineering Materials (BEM) Laboratory, School of Engineering and Physical Sciences, James Cook University, Townsville, Queensland 4811 (Australia); Walter, Rhys; Khakbaz, Hadis [Biomaterials and Engineering Materials (BEM) Laboratory, School of Engineering and Physical Sciences, James Cook University, Townsville, Queensland 4811 (Australia); Choe, Han-Choel [Department of Dental Materials, Chosun University, Gwangju 501-759 (Korea, Republic of)
2015-01-01
In this study, the in vitro degradation behaviour of titanium–tantalum (Ti–Ta) alloys (10–30 wt.% Ta) was investigated and compared with conventional implant materials, i.e., commercially pure titanium (Cp-Ti) and titanium–aluminium–vanadium (Ti6Al4V) alloy. Among the three Ti–Ta alloys studied, the Ti20Ta (6.3 × 10{sup −4} mm/y) exhibited the lowest degradation rate, followed by Ti30Ta (1.2 × 10{sup −3} mm/y) and Ti10Ta (1.4 × 10{sup −3} mm/y). All the Ti–Ta alloys exhibited lower degradation rate than that of Cp-Ti (1.8 × 10{sup −3} mm/y), which suggests that Ta addition to Ti is beneficial. As compared to Ti6Al4V alloy (8.1 × 10{sup −4} mm/y), the degradation rate of Ti20Ta alloy was lower by ∼ 22%. However, the Ti30Ta alloy, which has closer elastic modulus to that of natural bone, showed ∼ 48% higher degradation rate than that of Ti6Al4V alloy. Hence, to improve the degradation performance of Ti30Ta alloy, an intermediate thin porous layer was formed electrochemically on the alloy followed by calcium phosphate (CaP) electrodeposition. The coated Ti30Ta alloy (3.8 × 10{sup −3} mm/y) showed ∼ 53% lower degradation rate than that of Ti6Al4V alloy. Thus, the study suggests that CaP coated Ti30Ta alloy can be a viable material for load-bearing permanent implants. - Highlights: • In vitro degradation of titanium–tantalum (Ti–Ta) alloys was studied. • Ta addition to Ti is beneficial for better degradation resistance. • Ti–Ta alloys perform better than commercially pure Ti. • Calcium phosphate coated Ti–Ta alloy is superior to Ti6Al4V alloy.
Characterizing large strain crush response of redwood
International Nuclear Information System (INIS)
Cramer, S.M.; Hermanson, J.C.
1996-12-01
Containers for the transportation of hazardous and radioactive materials incorporate redwood in impact limiters. Redwood is an excellent energy absorber, but only the most rudimentary information exists on its crush properties. The objectives of the study were to fill the information gap by collecting triaxial load-deformation data for redwood; to use these data to characterize redwood crush, assess current wood failure theories, provide developments toward a complete stress-strain theory for redwood; and to review the literature on strain-rate effects on redwood crush performance. The load-deformation responses of redwood at temperature conditions corresponding to ambient (70 degrees F), 150 degrees F, and -20 degrees F conditions were measured in approximately 100 confined compression tests for crush levels leading to material densification. Data analysis provided a more complete description of redwood crush performance and a basis for assessing proposed general orthotropic stress-strain relationships for redwood. A review of existing literature indicated that strain-rate effects cause at most a 20 percent increase in crush stress parallel to grain
International Nuclear Information System (INIS)
Ledbetter, H.M.
1983-01-01
This chapter investigates the following five aspects of engineering-material solid-state elastic constants: general properties, interrelationships, relationships to other physical properties, changes during cooling from ambient to near-zero temperature, and near-zero-temperature behavior. Topics considered include compressibility, bulk modulus, Young's modulus, shear modulus, Poisson's ratio, Hooke's law, elastic-constant measuring methods, thermodynamic potentials, higher-order energy terms, specific heat, thermal expansivity, magnetic materials, structural phase transitions, polymers, composites, textured aggregates, and other-phenomena correlations. Some of the conclusions concerning polycrystalline elastic properties and their temperature dependence are: elastic constants are physical, not mechanical, properties which relate thermodynamically to other physical properties such as specific heat and thermal expansivity; elastic constants at low temperatures are nearly temperature independent, as required by the third law of thermodynamics; and elastic constants can be used to study directional properties of materials, such as textured aggregates and composites
Czech Academy of Sciences Publication Activity Database
Stachiv, Ivo; Kuo, Ch.-Y.; Fang, T.-H.; Mortet, Vincent
2016-01-01
Roč. 6, č. 4 (2016), 1-8, č. článku 045005. ISSN 2158-3226 R&D Projects: GA ČR GC15-13174J Institutional support: RVO:68378271 Keywords : elastic moduli * thin film structure * vibration resonance * error analysis * materials properties Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.568, year: 2016
Directory of Open Access Journals (Sweden)
Solenir Ruffato
2001-04-01
Full Text Available Neste trabalho investigou-se a viabilidade de se obter o módulo de compressão de grãos de milho, utilizando-se dados experimentais de força versus tempo, provenientes de testes de impacto, juntamente com uma análise estrutural elástica do processo. Os módulos de elasticidade foram determinados para grãos, a diferentes teores de umidade, submetidos a impactos de diferentes velocidades, e obtidos por um processo de otimização por meio da técnica de elementos finitos. Dois tipos de módulo foram avaliados: (a um módulo efetivo para todo o grão e (b um módulo para cada uma das três regiões, com diferentes características, segundo as quais o grão foi dividido. O teor de umidade e a velocidade de impacto influenciaram nos valores dos módulos. Módulos para grãos a 13,4% base úmida (b.u. foram maiores do que para aqueles a 20,0% b.u. A análise realizada (elástica mostrou-se ser mais adequada na obtenção de módulos de elasticidade de grãos a 13,4% b.u.; neste teor, os grãos apresentam características elásticas mais pronunciadas que quando a 20,0% b.u. e, nos grãos com altos teores de umidade, as características viscoelásticas tornam-se predominantes.In this study the viability of obtaining the corn compression modulus through an elastic structural analysis was investigated using force versus time data from grain impact tests. The moduli of elasticity of shelled corn at different moisture contents submitted to various impact velocities were determined. The moduli were obtained through an optimization process using the finite element technique. Two kinds of modulus were obtained: (a an effective modulus for the grain and (b a modulus for each one of the three regions, with different characteristics, in which the grain was divided. The moisture content and the impact velocity affected the modulus values. The moduli values for grains at 13.4% wet basis (w.b. were higher than those for grains at 20.0% w.b. The analysis used
Redwoods, restoration, and implications for carbon budgets
Madej, Mary Ann
2010-01-01
The coast redwoods (Sequoia sempervirens) of California have several unique characteristics that influence interactions between vegetation and geomorphic processes. Case studies, using a combination of in-channel wood surveys and an air photo inventory of landslides, illustrate current conditions in a redwood-dominated watershed undergoing restoration work, and the influence of wood loading and landslides on the carbon budget. Redwood trees have extremely large biomass (trunk wood volumes of 700 to 1000 m3) and are very decay-resistant; consequently, they have a large and persistent influence on in-channel wood loading. Large wood surveys indicate high wood loading in streams in uncut forests (0.3-0.5 m3/m2 of channel), but also show that high wood loading can persist in logged basin with unlogged riparian buffers because of the slow decay of fallen redwoods. Through a watershed restoration program, Redwood National Park increases in-channel wood loading in low-order streams, but the effectiveness of this technique has not yet been tested by a large flood. Another unique characteristic of redwood is its ability to resprout from basal burls after cutting, so that root strength may not decline as sharply following logging as in other types of forests. An air photo inventory of landslides following a large storm in 1997 indicated: 1) that in the Redwood Creek watershed the volume of material displaced by landslides in harvested areas was not related to the time elapsed since logging, suggesting that the loss of root strength was not a decisive factor in landslide initiation, 2) landslide production on decommissioned logging roads was half that of untreated roads, and 3) landslides removed an estimated 28 Mg of organic carbon/km2 from hillslopes. The carbon budget of a redwood-dominated catchment is dominated by the vegetative component, but is also influenced by the extent of mass movement, erosion control work, and in-channel storage of wood.
Kim, Yang; Kim, Young-Suk; Yoo, Sang-Ho; Kim, Kwang-Ok
2014-02-15
Six low-methoxy pectins with different degrees of methylesterification and amidation, and molecular weights were used to prepare gels with similar moduli of elasticity by varying the concentrations of pectin and calcium phosphate. Five aroma compounds were added to the gels and their sensory textural properties, release and perception of aromas were investigated. Sensory firmness, springiness, adhesiveness, chewiness and cohesiveness differed according to the gel type, even though the moduli of elasticity were not significantly different (ppectin exhibited the lowest release and perception for all the aroma compounds, while pectin-methylesterase-treated pectin gels exhibited relatively higher aroma release and perception. These results showed that the structural properties of pectins and gelling factors that increase the non-polar character of the gel matrices could decrease the release and perception of aromas in pectin gel systems. Copyright © 2013 Elsevier Ltd. All rights reserved.
Directory of Open Access Journals (Sweden)
О.A. Yukhymchuk
2015-08-01
It is established that the biomechanical indicators of bone extension are inferior to the similar performance in compression, bones in the presence of fixation devices have the higher strength in the area of healed fracture than the bones of the control group animals. When studying the function of bone regenerate for extension and compression, the best strength results were determined in bone samples with the presence of fixation device from β-Zr-Ti alloy. This study proves the feasibility of the development and introduction into clinical practice of orthopedic trauma surgeons of implants on the basis of low-modulus β-Zr-Ti alloy that will improve the results of treatment for long bone fractures and reduce the postoperative complications rate.
International Nuclear Information System (INIS)
Tane, M.; Hagihara, K.; Ueda, M.; Nakano, T.; Okuda, Y.
2016-01-01
Changes in the elastic properties during room-temperature aging (RT aging) of metastable Ti–Nb-based alloy single crystals with low body-centered cubic (bcc)-phase stability were investigated. The elastic stiffness components of Ti–Nb–Ta–Zr alloys with different Nb concentrations were measured by resonant ultrasound spectroscopy during RT aging; the results revealed that shear moduli c ′ and c 44 were increased by RT aging. In the alloy with the lowest Nb concentration, i.e., with the lowest bcc phase stability, shear moduli c ′ and c 44 were enhanced by the largest amount. The increase rates were ∼5% for 1.1 × 10 7 s (127 days), whereas the bulk modulus was hardly changed by aging. In Ti–Nb–Ta–Zr–O alloys with different oxygen concentrations, shear moduli c ′ and c 44 of the alloy with the lowest oxygen concentration increased most significantly. Moreover, the electrical resistivity of Ti–Nb–Ta–Zr and Ti–Nb–Ta–Zr–O alloys was increased by RT aging. Importantly, the enhancements of shear moduli and electrical resistivity were suppressed by increases in the bcc-phase stability (i.e., increase in the Nb concentration) and oxygen concentration; these factors are known to suppress ω (hexagonal) phase formation. However, transmission electron microscopy (TEM) observations revealed that only a diffuse ω structure—an ω-like lattice distortion—was formed after RT aging. On the basis of alloying element effects, TEM observations, and analysis of the changes in elastic properties by using a micromechanics model, it was deduced that the enhancements of shear moduli and electrical resistivity were possibly caused by the formation of a diffuse ω structure.
Inbreeding depression in selfs of redwood
W. J. Libby; B. G. McCutchan; C. I. Millar
1981-01-01
Given the polyploid chromosome constitution of Sequoia sempervirens, there was reason to question whether it would exhibit inbreeding depression. Preliminary results from studies of self and related outcross families are reported as a guide to the selection of trees for redwood seed orchards and breeding-orchards. The data indicate that, compared to...
Coast redwood live crown and sapwood
John-Pascal Berrill; Jesse L. Deffress; Jessica M. Engle
2012-01-01
Understanding crown rise and sapwood taper will help meet management objectives such as producing long branch-free boles for clear wood and old-growth restoration, or producing sawlogs with a high proportion of heartwood. Coast redwood (Sequoia sempervirens) tree crown ratio data were collected 20 years after partial harvesting in a 65-year-old second growth stand....
Structure and Young modulus of age hardening elinvar 45NKhT
International Nuclear Information System (INIS)
Baraz, V.R.; Strizhak, V.A.; Tsykin, D.N.
1996-01-01
The influence of quenching and ageing on structural features and Young modulus of precipitation hardening elinvar alloy 45 NKhT is under study. It is shown that the quenched alloy possesses a decreased elastic modulus which value drops with a quenching temperature increase. The ally ageing results in restoration of elastic modulus. The temperature range of Young modulus stability is shown to be independent of heat treatment conditions. The anomalies of elastic modulus in quenched alloy are conditioned by structural and magnetoelastic factors. The mechanisms of continuous and discontinuous precipitation mechanism has no effect on efficiency of Young modulus restoration. 13 refs., 6 figs
Coast redwood science symposium—2016: Past successes and future direction
Richard B. Standiford; Yana Valachovic
2017-01-01
There is no more iconic tree or more closely watched forest ecosystem than coast redwood. With its limited range and high value, the coast redwood forest is a microcosm of many of the emerging science and management issues facing todayâs forested landscapes. As new information is collected and new management approaches and treatments tried, it is critical that policies...
Using wood quality measures to evaluate second-growth redwood
Stephen L. Quarles; Yana. Vlachovic
2012-01-01
Redwood (Sequoia sempervirens) a valued species for use in appearance grade applications, such as decking, exterior siding and interior paneling, because of its dimensional stability. It is also valued for certain exterior-use applications because of its natural decay resistance. Studies have found that young-growth redwood is less resistant to...
Rare Plants of the Redwood Forest and Forest Management Effects
Teresa Sholars; Clare Golec
2007-01-01
Coast redwood forests are predominantly a timber managed habitat type, subjected to repeated disturbances and short rotation periods. What does this repeated disturbance mean for rare plants associated with the redwood forests? Rare plant persistence through forest management activities is influenced by many factors. Persistence of rare plants in a managed landscape is...
2017-09-01
The mechanistic-empirical pavement design method requires the elastic resilient modulus as the key input for characterization of geomaterials. Current density-based QA procedures do not measure resilient modulus. Additionally, the density-based metho...
Temperature dependence of Young's modulus of silica refractories
Czech Academy of Sciences Publication Activity Database
Gregorová, E.; Černý, Martin; Pabst, W.; Esposito, L.; Zanelli, C.; Hamáček, J.; Kutzendorfer, J.
2015-01-01
Roč. 41, č. 1 (2015), s. 1129-1138 ISSN 0272-8842 Institutional support: RVO:67985891 Keywords : mechanical properties * elastic modulus (Young's modulus ) * SiO2 * Silica brick materials (cristobalite, tridymite) Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass Impact factor: 2.758, year: 2015
International Nuclear Information System (INIS)
Vavra, G.
1978-01-01
Considered are the limit and the intermediate values of the Young modulus E, modulus of shear G and of linear modulus of compression K obtainable at various temperatures (4.2 to 1133 K) for single crystals of α-zirconium. Determined and presented are the corrected isotropic elasticity characteristics of E, G, K over the above range of temperatures of textured and non-textured α-Zr
Experimental Young's modulus calculations
International Nuclear Information System (INIS)
Chen, Y.; Jayakumar, R.; Yu, K.
1994-01-01
Coil is a very important magnet component. The turn location and the coil size impact both mechanical and magnetic behavior of the magnet. The Young's modulus plays a significant role in determining the coil location and size. Therefore, Young's modulus study is essential in predicting both the analytical and practical magnet behavior. To determine the coil Young's modulus, an experiment has been conducted to measure azimuthal sizes of a half quadrant QSE101 inner coil under different loading. All measurements are made at four different positions along an 8-inch long inner coil. Each measurement is repeated three times to determine the reproducibility of the experiment. To ensure the reliability of this experiment, the same measurement is performed twice with a open-quotes dummy coil,close quotes which is made of G10 and has the same dimension and similar azimuthal Young's modulus as the inner coil. The difference between the G10 azimuthal Young's modulus calculated from the experiments and its known value from the manufacturer will be compared. Much effort has been extended in analyzing the experimental data to obtain a more reliable Young's modulus. Analysis methods include the error analysis method and the least square method
International Nuclear Information System (INIS)
Inagaki, M.
2000-01-01
The internal friction and Young's modulus of a series of superconductors Nd x Y 1-x Ba 2 Cu 3 O y (x = 0.0-1.0) were measured over the temperature range from 300 to 1050 K using a 200 kHz LiNbO3 piezoelectric composite oscillator. Anelastic relaxation peaks due to oxygen migration were observed at about 850 K. The minimum Young's modulus, which is related to the orthorhombic-to-tetragonal phase transition, was also observed near this temperature. The temperature at the minimum Young's modulus decreased with an increase in the neodymium composition. In contrast, the internal friction peak temperature showed an unsystematic shift with an increase in x, while changes of the average cell structure exhibited a linear relationship when plotted versus the average ionic radius for trivalent rare-earth ions with the coordination number eight. (author)
Decomposition and N cycling changes in redwood forests caused by sudden oak death
Richard C. Cobb; David M. Rizzo
2012-01-01
Phytophthora ramorum is an emergent pathogen in redwood forests which causes the disease sudden oak death. Although the disease does not kill coast redwood (Sequoia sempervirens), extensive and rapid mortality of tanoak (Notholithocarpus densiflorus) has removed this...
The New Economies of the Redwood Region in the 21st Century
William Stewart
2007-01-01
The redwood region of California has experienced a number of major land use changes over the past one hundred and fifty years. A review of recent economic trends in the redwood region suggests the emergence of three new themes. First, it appears that the transition from an old growth to a young growth redwood industry is essentially complete. Lower revenues and...
Influence of various factors on the Young modulus of metals
International Nuclear Information System (INIS)
Drapkin, B.M.
1980-01-01
The equivalence of temperature and pressure effects in the elastic area on the Young modulus of different metals (Ni, Mo, W, Na, Fe and ets.) is established on the basis of the analysis of literature and calculated data. It is shown that the value of the change in the Young modulus of the alloy is connected with mutual arrangement of alloy components in the periodic system of elements
Temperature dependence of elastic properties of paratellurite
International Nuclear Information System (INIS)
Silvestrova, I.M.; Pisarevskii, Y.V.; Senyushenkov, P.A.; Krupny, A.I.
1987-01-01
New data are presented on the temperature dependence of the elastic wave velocities, elastic stiffness constants, and thermal expansion of paratellurite. It is shown that the external pressure appreciably influences the elastic properties of TeO 2 , especially the temperature dependence of the elastic modulus connected with the crystal soft mode. (author)
Modelling the elastic properties of cellulose nanopaper
DEFF Research Database (Denmark)
Mao, Rui; Goutianos, Stergios; Tu, Wei
2017-01-01
The elastic modulus of cellulose nanopaper was predicted using a two-dimensional (2D) micromechanical fibrous network model. The elastic modulus predicted by the network model was 12 GPa, which is well within the range of experimental data for cellulose nanopapers. The stress state in the network...
Roles of Fog and Topography in Redwood Forest Hydrology
Francis, E. J.; Asner, G. P.
2017-12-01
Spatial variability of water in forests is a function of both climatic gradients that control water inputs and topo-edaphic variation that determines the flows of water belowground, as well as interactions of climate with topography. Coastal redwood forests are hydrologically unique because they are influenced by coastal low clouds, or fog, that is advected onto land by a strong coastal-to-inland temperature difference. Where fog intersects the land surface, annual water inputs from summer fog drip can be greater than that of winter rainfall. In this study, we take advantage of mapped spatial gradients in forest canopy water storage, topography, and fog cover in California to better understand the roles and interactions of fog and topography in the hydrology of redwood forests. We test a conceptual model of redwood forest hydrology with measurements of canopy water content derived from high-resolution airborne imaging spectroscopy, topographic variables derived from high-resolution LiDAR data, and fog cover maps derived from NASA MODIS data. Landscape-level results provide insight into hydrological processes within redwood forests, and cross-site analyses shed light on their generality.
Bat use of remnant old-growth redwood stands
William J. Zielinski; Steven T. Gellman
1999-01-01
Most of the old-growth redwood (Sequoia sempervirens) in Calfornia has been cut; regenerating forests will probably never resemble those that were harvested, and what old growth remains on private land occurs in small, isolated remnant patches. The landscapes in which these stands occur differ so markedly from their original condition that their...
Life-Cycle Inventory Analysis of Manufacturing Redwood Decking
Richard D. Bergman; Han-Sup Han; Elaine Oneil; Ivan L. Eastin
2012-01-01
Green building has become increasingly important. Therefore, consumers and builders often take into account the environmental attributes of a building material. This study determined the environmental attributes associated with manufacturing 38-mm Ã 138-mm (nominal 2 Ã 6) redwood decking in northern California using the life-cycle inventory method. Primary data...
Plant Uptake of Atmospheric Carbonyl Sulfide in Coast Redwood Forests
Campbell, J. E.; Whelan, M. E.; Berry, J. A.; Hilton, T. W.; Zumkehr, A.; Stinecipher, J.; Lu, Y.; Kornfeld, A.; Seibt, U.; Dawson, T. E.; Montzka, S. A.; Baker, I. T.; Kulkarni, S.; Wang, Y.; Herndon, S. C.; Zahniser, M. S.; Commane, R.; Loik, M. E.
2017-12-01
The future resilience of coast redwoods (Sequoia sempervirens) is now of critical concern due to the detection of a 33% decline in California coastal fog over the 20th century. However, ecosystem-scale measurements of photosynthesis and stomatal conductance are challenging in coast redwood forests, making it difficult to anticipate the impacts of future changes in fog. To address this methodological problem, we explore coastal variations in atmospheric carbonyl sulfide (COS or OCS), which could potentially be used as a tracer of these ecosystem processes. We conducted atmospheric flask campaigns in coast redwood sites, sampling at surface heights and in the canopy ( 70 m), at the University of California Landels-Hill Big Creek Reserve and Big Basin State Park. We simulated COS atmosphere-biosphere exchange with a high-resolution 3-D model to interpret these data. Flask measurements indicated a persistent daytime drawdown between the coast and the downwind forest (45 ± 6 ppt COS) that is consistent with the expected relationship between COS plant uptake, stomatal conductance, and gross primary production. Other sources and sinks of COS that could introduce noise to the COS tracer technique (soils, anthropogenic activity, nocturnal plant uptake, and surface hydrolysis on leaves) are likely to be small relative to daytime COS plant uptake. These results suggest that COS measurements may be useful for making ecosystem-scale estimates of carbon, water, and energy exchange in coast redwood forests.
Elastic properties of Gum Metal
International Nuclear Information System (INIS)
Kuramoto, Shigeru; Furuta, Tadahiko; Hwang, Junghwan; Nishino, Kazuaki; Saito, Takashi
2006-01-01
In situ X-ray diffraction measurements under tensile loading and dynamic mechanical analysis were performed to investigate the mechanisms of elastic deformation in Gum Metal. Tensile stress-strain curves for Gum Metal indicate that cold working substantially decreases the elastic modulus while increasing the yield strength, thereby confirming nonlinearity in the elastic range. The gradient of each curve decreased continuously to about one-third its original value near the elastic limit. As a result of this decrease in elastic modulus and nonlinearity, elastic deformability reaches 2.5% after cold working. Superelasticity is attributed to stress-induced martensitic transformations, although the large elastic deformation in Gum Metal is not accompanied by a phase transformation
Directory of Open Access Journals (Sweden)
André L. Christoforo
2012-10-01
. The use of round timber as a beam is very attractive, since it does not need to be processed, such as lumber. The design of structural timber elements requires the determination of its physical and mechanical properties in which are obtained based on the recommendations of engineering standards. In case of round timber, the national standards dealing with the determination of strength and stiffness properties are in term for more than twenty years with no technical review. Overall, both national and international standards consider truncated-cone geometry for cylindrical logs of wood, resulting in simplified equations unable to predict the effect of shape irregularities on the longitudinal modulus of elasticity. This paper aims to evaluate the effect of shape irregularity of round timber of Corymbia citriodora and Pinus caribaea to determine the longitudinal modulus of elasticity. The three-point bending test is used to determine the modulus, considering a simplified analytical model, with constant circular section for the element. The irregularities of the wood are considered in the numerical models based on a beam and three-dimensional finite elements. The results showed statistical equivalence between the modulus of elasticity for both methods of calculation, indicating that the constant circular section is a reasonable assumption for the wooden here evaluated.
Atomistic Calculation of Elastic Moduli in Strained Silicon
National Research Council Canada - National Science Library
Zhu, Richard; Pan, Ernian; Chung, Peter W; Cai, Xinli; Liew, Kim M; Buldum, Alper
2007-01-01
.... Using our approach, the bulk modulus, effective elastic stiffnesses C11, C12, and C44 of the strained silicon, including also the effective Young's modulus and Poisson's ratio, are all calculated...
Estimation of the Young’s modulus of cellulose Iß by MM3 and quantum mechanics
Young’s modulus provides a measure of the resistance to deformation of an elastic material. In this study, modulus estimations for models of cellulose Iß relied on calculations performed with molecular mechanics (MM) and quantum mechanics (QM) programs. MM computations used the second generation emp...
Determination of young's modulus of PZT-influence of cantilever orientation
Nazeer, H.; Woldering, L.A.; Abelmann, Leon; Elwenspoek, Michael Curt
Calculation of the resonance frequency of cantilevers fabricated from an elastically anisotropic material requires the use of an effective Young’s modulus. In this paper a technique to determine the appropriate effective Young’s modulus for arbitrary cantilever geometries is introduced. This
Determining the complex modulus of alginate irreversible hydrocolloid dental material.
King, Shalinie; See, Howard; Thomas, Graham; Swain, Michael
2008-11-01
The aim of the study is to investigate the visco-elastic response of an alginate irreversible hydrocolloid dental impression material during setting. A novel squeeze film Micro-Fourier Rheometer (MFR, GBC Scientific Equipment, Australia) was used to determine the complex modulus of an alginate irreversible hydrocolloid dental impression material (Algident, ISO 1563 Class A Type 1, Dentalfarm Australia Pty. Ltd.) during setting after mixing. Data was collected every 30s for 10 min in one study and every 10 min for a total of 60 min in another study. A high level of repeatability was observed. The results indicate that the MFR is capable of recording the complex shear modulus of alginate irreversible hydrocolloid for 60 min from the start of mixing and to simultaneously report the changing visco-elastic parameters at all frequencies between 1 Hz and 100 Hz. The storage modulus shows a dramatic increase to 370% of its starting value after 6 min and then reduces to 55% after 60 min. The loss modulus increases to a maximum of 175% of its starting value after 10 min and then reduces to 94% after 60 min. The MFR enables the changes in the complex modulus through the complete setting process to be followed. It is anticipated this approach may provide a better method to compare the visco-elastic properties of impression materials and assist with identification of optimum types for different clinical requirements. The high stiffness of the instrument and the use of band-limited pseudo-random noise as the input signal are the main advantages of this technique over conventional rheometers for determining the changes in alginate visco-elasticity.
Post-fire response of coast redwood one year after the Mendocino lightning complex fires
Robert B. Douglas; Tom. Bendurel
2012-01-01
Coast redwood (Sequoia sempervirens) forests have undergone significant changes over the past century and are now in state more conducive for wildfires. Because fires have been uncommon in redwood forests over the past 80 years, managers have limited data to make decisions about the post-fire environment. In June 2008, a series of lightning storms...
'Pygmy' old-growth redwood characteristics on an edaphic ecotone in Mendocino County, California
Will Russell; Suzie. Woolhouse
2012-01-01
The 'pygmy forest' is a specialized community that is adapted to highly acidic, hydrophobic, nutrient deprived soils, and exists in pockets within the coast redwood forest in Mendocino County. While coast redwood is known as an exceptionally tall tree, stunted trees exhibit unusual growth-forms on pygmy soils. We used a stratified random sampling procedure to...
Bark water uptake promotes localized hydraulic recovery in coastal redwood crown
J. Mason Earles; Or Sperling; Lucas C. R. Silva; Andrew J. McElrone; Craig R. Brodersen; Malcolm P. North; Maciej A. Zwieniecki
2015-01-01
Coastal redwood (Sequoia sempervirens), the worldâs tallest tree species, rehydrates leaves via foliar water uptake during fog/rain events. Here we examine if bark also permits water uptake in redwood branches, exploring potential flow mechanisms and biological significance. Using isotopic labelling and microCT imaging, we observed that water...
Does water chemistry limit the distribution of New Zealand mud snails in Redwood National Park?
Vazquez, Ryan; Ward, Darren M.; Sepulveda, Adam
2016-01-01
New Zealand mud snails (NZMS) are exotic mollusks present in many waterways of the western United States. In 2009, NZMS were detected in Redwood Creek in Redwood National Park, CA. Although NZMS are noted for their ability to rapidly increase in abundance and colonize new areas, after more than 5 years in Redwood Creek, their distribution remains limited to a ca. 300 m reach. Recent literature suggests that low specific conductivity and environmental calcium can limit NZMS distribution. We conducted laboratory experiments, exposing NZMS collected from Redwood Creek to both natural waters and artificial treatment solutions, to determine if low conductivity and calcium concentration limit the distribution of NZMS in Redwood National Park. For natural water exposures, we held NZMS in water from their source location (conductivity 135 μS/cm, calcium 13 mg/L) or water from four other locations in the Redwood Creek watershed encompassing a range of conductivity (77–158 μS/cm) and calcium concentration (4 months) in the lowest conductivity waters from Redwood Creek and all but the lowest-conductivity treatment solutions, regardless of calcium concentration. However, reproductive output was very low in all natural waters and all low-calcium treatment solutions. Our results suggest that water chemistry may inhibit the spread of NZMS in Redwood National Park by reducing their reproductive output.
Fog and soil weathering as sources of nutrients in a California redwood forest
Holly A. Ewing; Kathleen C. Weathers; Amanda M. Lindsey; Pamela H. Templer; Todd E. Dawson; Damon C. Bradbury; Mary K. Firestone; Vanessa K.S. Boukili
2012-01-01
Fog water deposition is thought to influence the ecological function of many coastal ecosystems, including coast redwood forests. We examined cation and anion inputs from fog and rain, as well as the fate of these inputs, within a Sonoma County, California, coast redwood forest to elucidate the availability of these ions and some of the biotic and abiotic processes...
Cradle-to-gate life cycle impacts of redwood forest resource harvesting in northern California
Han-Sup Han; Elaine Oneil; Richard D. Bergman; Ivan L. Eastin; Leonard R. Johnson
2015-01-01
The first life cycle impact assessment for redwood (Sequoia sempervirens) forest management activities (i.e. a cradle-to-sawmill gate input) including the growing, harvesting, and hauling of redwood sawlogs to a sawmill was completed. In the stump-to-truck timber harvesting analysis, primary transport activities such as skidding and yarding consumed...
Northern California redwood forests provide important seasonal habitat for migrant bats
Theodore J. Weller; Craig A. Stricker
2012-01-01
Bats are known to roost in redwood forests year-round, but their activities outside the summer season are poorly understood. To improve understanding of the use of redwoods by resident and migrant bats, we conducted 74 mist net surveys between February 2008 and October 2010. Captures were dominated by Yuma myotis (M. yumanensis) in the summer and...
Natural seedlings and sprouts after regeneration cuttings in old-growth redwood
Kenneth N. Boe
1975-01-01
Natural regeneration of harvested old-growth stands of redwood (Sequoia sempervirens) is one way to start a new forest that is needed quickly for continuous timber production. Natural seedlings and sprouts developing after stands were cut were studied on the Redwood Experimental Forest, northern California. Three types of regeneration cuttings were...
Predicting redwood productivity using biophysical data, spatial statistics and site quality indices
John-Pascal Berrill; Kevin L. O’Hara; Shawn Headley
2017-01-01
Coast redwood (Sequoia sempervirens (D. Don) Endl.) height growth and basal area growth are sensitive to variations in site quality. Site factors known to be correlated with redwood stand growth and yield include topographic variables such as position on slope, exposure, and the composite variable: topographic relative moisture index. Species...
Directory of Open Access Journals (Sweden)
André L. Christoforo
2011-10-01
Full Text Available Currently, the standards that deal with the determination of the properties of rigidity and strength for structural round timber elements do not take in consideration in their calculations and mathematical models the influence of the existing irregularities in the geometry of these elements. This study has as objective to determine the effective value of the modulus of longitudinal elasticity for structural round timber pieces of the Eucalyptus citriodora genus by a technique of optimization allied to the Inverse Analysis Method, to the Finite Element Method and the Least Square Method.Atualmente, os documentos normativos que tratam da determinação das propriedades de rigidez e resistência para elementos estruturais roliços de madeira, não levam em consideração em seus cálculos e modelos matemáticos a influência das irregularidades existentes na geometria dessas peças. Este trabalho tem como objetivo determinar o efetivo valor do módulo de elasticidade longitudinal para peças estruturais roliças de madeira do gênero Eucalyptus citriodora, por intermédio de uma técnica de otimização aliada ao Método da Análise Inversa, ao Método dos Elementos Finitos e ao Método dos Mínimos Quadrados.
Directory of Open Access Journals (Sweden)
Pedro Gutemberg de Alcântara Segundinho
2012-12-01
Full Text Available Existem diversas técnicas para caracterização do módulo de elasticidade de madeiras e, dentre as atualmente empregadas, destacam-se aquelas que utilizam as frequências naturais de vibração, por serem técnicas não destrutivas e, portanto, apresentarem resultados que podem ser repetidos e comparados ao longo do tempo. Este trabalho teve como objetivo avaliar a eficácia, dos métodos de ensaios baseados nas frequências naturais de vibração comparando-os aos resultados obtidos na flexão estática na obtenção das propriedades elásticas em peças estruturais de madeira de reflorestamento que são usualmente empregadas na construção civil. Foram avaliadas 24 vigas de Eucalyptus sp. com dimensões nominais (40 x 60 x 2.000 mm e 14 vigas de Pinus oocarpa com dimensões nominais (45 x 90 x 2.300 mm, ambas sem tratamento; 30 pranchas com dimensões nominais (40 x 240 x 2.010 mm e 30 pranchas com dimensões nominais (40 x 240 x 3.050 mm, ambas de Pinnus oocarpa e com tratamento preservativo à base de Arseniato de Cobre Cromatado - CCA. Os resultados obtidos apresentaram boa correlação quando comparados aos resultados obtidos pelo método mecânico de flexão estática, especialmente quando empregada a frequência natural de vibração longitudinal. O emprego da frequência longitudinal mostrou-se confiável e prático, portanto recomendada para a determinação do módulo de elasticidade de peças estruturais de madeira. Verificou-se ainda que, empregando a frequência longitudinal, não há necessidade de um suporte específico para os corpos de prova ou calibrações prévias, reduzindo assim o tempo de execução e favorecendo o ensaio de grande quantidade de amostras.There are several techniques to characterize the elastic modulus of wood and those currently using the natural frequencies of vibration stand out as they are non-destructive techniques, producing results that can be repeated and compared over time. This study reports
Relationship between radial compressive modulus of elasticity and shear modulus of wood
Jen Y. Liu; Robert J. Ross
2005-01-01
Wood properties in transverse compression are difficult to determine because of such factors as anatomical complexity, specimen geometry, and loading conditions. The mechanical properties of wood, considered as an anisotropic or orthotropic material, are related by certain tensor transformation rules when the reference coordinate system changes its orientation. In this...
ELASTIC CHARACTERIZATION OF Eucalyptus citriodora WOOD
Directory of Open Access Journals (Sweden)
Adriano Wagner Ballarin
2003-01-01
Full Text Available This paper contributed to the elastic characterization of Eucalyptus citriodora grown inBrazil, considering an orthotropic model and evaluating its most important elastic constants.Considering this as a reference work to establish basic elastic ratios — several important elasticconstants of Brazilian woods were not determined yet - the experimental set-up utilized one tree of 65years old from plantations of “Horto Florestal Navarro de Andrade”, at Rio Claro-SP, Brazil. All theexperimental procedures attended NBR 7190/97 – Brazilian Code for wooden structures –withconventional tension and compression tests. Results showed statistical identity between compressionand tension modulus of elasticity. The relation observed between longitudinal and radial modulus ofelasticity was 10 (EL/ER ≈ 10 and same relation, considering shear modulus (modulus of rigidity was20 (EL/GLR ≈ 20. These results, associated with Poisson’s ratios herein determined, allow theoreticalmodeling of wood mechanical behavior in structures.
Young's Modulus of a Marshmallow
Pestka, Kenneth A., II
2008-01-01
When teaching the subject of elasticity, it is often difficult to find a straightforward quantitative laboratory that can give a "hands-on" feel for the subject. This paper presents an experiment that demonstrates the essentials of elasticity by observing the behavior of marshmallows under a compressive load. Like other marshmallow-based…
Kadota, Kenji; Kobayashi, Tatsuo; Saga, Ikumi; Sumita, Keigo
2018-04-01
We propose a new model of single-field D-term inflation in supergravity, where the inflation is driven by a single modulus field which transforms non-linearly under the U(1) gauge symmetry. One of the notable features of our modulus D-term inflation scenario is that the global U(1) remains unbroken in the vacuum and hence our model is not plagued by the cosmic string problem which can exclude most of the conventional D-term inflation models proposed so far due to the CMB observations.
Chromium effect on the Young modulus and thermoelastic coefficient of elinvars
International Nuclear Information System (INIS)
Sazykina, A.V.; Khomenko, O.A.
1976-01-01
The effect was studied of thermal and thermal-mechanical treatment upon the elastic modules and its temperature coefficient in iron-nickel Elinvars with different chromium contents (from 0 to 6.7%). It has been shown that doping with chromium results in an increase in the modulus of elasticity of Elinvars after hardening. The elastic modulus of alloys containing no chromium increases after a cold plastic deformation (drawing), whereas that of chromous Elinvars decreases upon such a treatment. It has been established that the elastic modulus of hardened and cold drawn after hardening Elinvars increases upon ageing. An increase in chromium content in iron-nickel Elinvars reduces the effect of the temperature of ageing upon the thermoelastic coefficient during the usual heat treatment and the thermalmechanical treatment and lowers its sensitivity to the influence of an external magnetic field [ru
Yield and ultrasonic modulus of elasticity of red maple veneer
Robert J. Ross; Steven Verhey; John R. Erickson; John W. Forsman; Brian K. Brashaw; Crystal L. Pilon; Xiping Wang
2004-01-01
The purpose of the study was to assess the potential for using red maple sawlogs to manufacture laminated veneer lumber (LVL). The primary objective was to determine the yield of ultrasonically graded veneer from red maple logs. A sample of 48 logs was obtained from six Eastern and Lake States in the United States. The logs were visually graded and shipped to a plywood...
Determining modulus of elasticity of ancient structural timber
Houjiang Zhang; Lei Zhu; Yanliang Sun; Xiping Wang; Haicheng Yan
2011-01-01
During maintenance of ancient timber architectures, it is important to determine mechanical properties of the wood component materials non-destructively and effectively, so that degraded members may be replaced or repaired to avoid structural failure. Experimental materials are four larch (Larix principis-rupprechtii Mayr.) components, which were taken down from the...
Elastic modulus of Extreme Ultraviolet exposed single-layer graphene
Mund, Baibhav Kumar; Gao, An; Sturm, Jacobus Marinus; Lee, Christopher James; Bijkerk, Frederik
2015-01-01
Highly transparent membranes are required for a number of applications, such as protective coatings for components in Extreme Ultraviolet (EUV) lithography, beam splitters (EUV pump-probe experiments), transmission gratings, and reticles. Graphene is an excellent candidate due to its high tensile
Sapwood area - leaf area relationships for coast redwood
Stancioiu, P T; O'Hara, K L
2005-01-01
Coast redwood (Sequoia sempervirens (D. Don) Endl.) trees in different canopy strata and crown positions were sampled to develop relationships between sapwood cross-sectional area and projected leaf area. Sampling occurred during the summers of 2000 and 2001 and covered tree heights ranging from 7.7 to 45.2 m and diameters at breast height ranging from 9.4 to 92.7 cm. Foliage morphology varied greatly and was stratified into five types based on needle type (sun or shade) and twig color. A str...
CONCERNING THE ELASTIC ORTHOTROPIC MODEL APPLIED TO WOOD ELASTIC PROPERTIES
Tadeu Mascia,Nilson
2003-01-01
Among the construction materials, wood reveals an orthotropic pattern, because of unique characteristics in its internal structure with three axes of wood biological directions (longitudinal, tangential and radial). elastic symmetry: longitudinal, tangential and radial, reveals an orthotropic pattern. The effect of grain angle orientation onin the elastic modulus constitutes the fundamental cause forof wood anisotropy. It is responsible for the greatest changes in the values of the constituti...
Examining Young's modulus for wood
International Nuclear Information System (INIS)
Perkalskis, Benjamin S; Freeman, J Reuben; Suhov, Alexander
2004-01-01
Symmetry considerations, dimensional analysis and simple approximations are used to derive a formula for Young's modulus of a simple anisotropic system, a straight-layer wood bar whose fibre axis makes an angle with respect to the bar's longitudinal axis. Agreement between the derived formula and experiment (carried out in far from ideal conditions) is within 10%. Improvements and extensions are suggested for this undergraduate physics experiment
Low modulus Ti–Nb–Hf alloy for biomedical applications
Energy Technology Data Exchange (ETDEWEB)
González, M., E-mail: Marta.Gonzalez.Colominas@upc.edu [Department of Materials Science and Metallurgy, Universitat Politècnica de Catalunya (UPC), Avda. Diagonal 647, 08028 Barcelona (Spain); Materials Science, Elisava Escola Superior de Disseny i Enginyeria de Barcelona, La Rambla 30-32, 08002 Barcelona (Spain); Peña, J. [Department of Materials Science and Metallurgy, Universitat Politècnica de Catalunya (UPC), Avda. Diagonal 647, 08028 Barcelona (Spain); Materials Science, Elisava Escola Superior de Disseny i Enginyeria de Barcelona, La Rambla 30-32, 08002 Barcelona (Spain); Gil, F.J.; Manero, J.M. [Department of Materials Science and Metallurgy, Universitat Politècnica de Catalunya (UPC), Avda. Diagonal 647, 08028 Barcelona (Spain); Ciber-BBN (Spain)
2014-09-01
β-Type titanium alloys with a low elastic modulus are a potential strategy to reduce stress shielding effect and to enhance bone remodeling in implants used to substitute failed hard tissue. For biomaterial application, investigation on the mechanical behavior, the corrosion resistance and the cell response is required. The new Ti25Nb16Hf alloy was studied before and after 95% cold rolling (95% C.R.). The mechanical properties were determined by tensile testing and its corrosion behavior was analyzed by potentiostatic equipment in Hank's solution at 37 °C. The cell response was studied by means of cytotoxicity evaluation, cell adhesion and proliferation measurements. The stress–strain curves showed the lowest elastic modulus (42 GPa) in the cold worked alloy and high tensile strength, similar to that of Ti6Al4V. The new alloy exhibited better corrosion resistance in terms of open circuit potential (E{sub OCP}), but was similar in terms of corrosion current density (i{sub CORR}) compared to Ti grade II. Cytotoxicity studies revealed that the chemical composition of the alloy does not induce cytotoxic activity. Cell studies in the new alloy showed a lower adhesion and a higher proliferation compared to Ti grade II presenting, therefore, mechanical features similar to those of human cortical bone and, simultaneously, a good cell response. - Highlights: • Presents low elastic modulus and high strength and elastic deformability. • Exhibits good biocompatibility in terms of cytotoxicity and cell response. • Corrosion resistance of this alloy is good, similar to that of Ti grade II. • Potential candidate for implants used to substitute failed hard tissue.
Young's modulus of a copper-stabilized niobium-titanium superconductive wire
International Nuclear Information System (INIS)
Ledbetter, H.M.; Moulder, J.C.; Austin, M.W.
1980-01-01
Young's modulus was determined for a 0.6-mm-dia niobium-titanium superconductive wire. Two methods were used: continuous-wave-resonance and laser-pulse-excitation. Young's moduli were also determined for the components - copper and Nb-Ti - in both wire and bulk forms. Some mechanical-deformation effects on Young's modulus were also measured. From the component' elastic moduli, that of the composite was predicted accurately by a simple rule-of-mixtures relationship
An individual-based growth and competition model for coastal redwood forest restoration
van Mantgem, Phillip J.; Das, Adrian J.
2014-01-01
Thinning treatments to accelerate coastal redwood forest stand development are in wide application, but managers have yet to identify prescriptions that might best promote Sequoia sempervirens (Lamb. ex D. Don) Endl. (redwood) growth. The creation of successful thinning prescriptions would be aided by identifying the underlying mechanisms governing how individual tree growth responds to competitive environments in coastal redwood forests. We created a spatially explicit individual-based model of tree competition and growth parameterized using surveys of upland redwood forests at Redwood National Park, California. We modeled competition for overstory trees (stems ≥ 20 cm stem diameter at breast height, 1.37 m (dbh)) as growth reductions arising from sizes, distances, and species identity of competitor trees. Our model explained up to half of the variation in individual tree growth, suggesting that neighborhood crowding is an important determinant of growth in this forest type. We used our model to simulate the effects of novel thinning prescriptions (e.g., 40% stand basal area removal) for redwood forest restoration, concluding that these treatments could lead to substantial growth releases, particularly for S. sempervirens. The results of this study, along with continued improvements to our model, will help to determine spacing and species composition that best encourage growth.
International Nuclear Information System (INIS)
Brandt, E.H.
1976-01-01
The elastic properties of the flux line lattice in Type II superconductors as calculated from the Ginsburg-Landau theory are discussed. They are non-local on a length scale much larger than the flux line distance and divergent at Hsub(c2). The compression modulus may become much smaller than its long-wavelength limit, B 2 /4π, and if the deformation is not homogeneous, at Hsub(c2) the modulus vanishes as (Hsub(c2) - B) 2 . At arbitrary induction the compression modulus of strain waves with wavelengths of several flux line distances is of the order of the (small) shear modulus. (author)
International Nuclear Information System (INIS)
Neklyudov, I.M.; Sytin, V.I.; Voevodin, V.N.
2003-01-01
The researches results of influence of predeformations and annealings on elastic and plastic characteristics of vacuum melting and yttrium doped copper are given. The interrelation between elastic and plastic characteristics has been shown. It is shown that the yield stress and modulus of elongation essentially depend on predeformations and annealings and they are the structurally sensitive characteristics
Emily Limm; Kevin Simonin; Tod. Dawson
2012-01-01
Fog inundates the coast redwood forests of northern California frequently during the summer months (May to September) when rainfall is largely absent (Azevedo and Morgan 1974, Byers 1953, Oberlander 1956). This maritime fog modifies otherwise warm and dry summer climate by increasing humidity, decreasing the air temperature, reducing solar radiation, and...
R. Bergman; H. Sup-Han; E. Oneil; I. Eastin
2013-01-01
The goal of the study was to conduct a life-cycle inventory (LCI) of California redwood (Sequoia sempervirens) decking that would quantify the critical environmental impacts of decking from cradle to grave. Using that LCI data, a life-cycle assessment (LCA) was produced for redwood decking. The results were used to compare the environmental footprint...
Energy Technology Data Exchange (ETDEWEB)
Liu, C H; Li, J; Singh, M; Larin, K V [Department of Biomedical Engineering, University of Houston, Houston, Texas (United States); Skryabina, M N [Department of Physics, M.V. Lomonosov Moscow State University (Russian Federation); Sobol, E N [Institute of Laser and Information Technologies, Russian Academy of Sciences, Troitsk, Moscow Region (Russian Federation)
2014-08-31
The development of an effective system to monitor the changes in the elastic properties of cartilage tissue with increasing temperature in laser reconstruction is an urgent practical task. In this paper, the use of phase-sensitive optical coherence elastography for detection of elastic waves in the sample has allowed Young's modulus of cartilage tissue to be measured directly during heating. Young's modulus was calculated from the group velocity of propagation of elastic waves excited by means of a system supplying focused air pulses. The measurement results are in agreement with the results of measurements of the modulus of elasticity under mechanical compression. The technique developed allows for noninvasive measurements; its development is promising for the use in vivo. (laser biophotonics)
Directory of Open Access Journals (Sweden)
Adriano W. Ballarin
2005-04-01
Full Text Available A madeira de Pinus sp. tem utilização crescente na indústria madeireira brasileira. O decréscimo constante do suprimento de árvores adultas com grandes diâmetros, provenientes de florestas naturais, tornou comum a produção de madeira em ciclos curtos, com grande proporção de madeira juvenil. Resultados de diversas pesquisas têm reportado que o módulo de elasticidade e a resistência a diferentes solicitações mecânicas são seriamente afetados pela presença de madeira juvenil. Este trabalho teve por objetivo determinar o módulo de elasticidade da madeira juvenil e adulta de Pinus taeda L. a partir da constante dinâmica C LL, obtida em ensaios não-destrutivos de ultra-som. A madeira de P. taeda era originária de plantios da Estação Experimental de Itapeva - SP, sendo amostrados seis indivíduos arbóreos com 34 anos de idade. Os corpos-de-prova (4 cm x 4 cm x 45 cm foram obtidos separadamente das regiões de madeira juvenil e adulta da prancha central, previamente submetida à secagem industrial (umidade final de 12%, para a determinação da constante dinâmica por meio de ensaios de ultra-som. Para avaliar a sensibilidade do método do ultra-som, os corpos-de-prova foram ensaiados destrutivamente à compressão paralela. Os resultados mostraram boa sensibilidade do método do ultra-som (R² » 0,90 na avaliação desse parâmetro mecânico da madeira juvenil e adulta.Pinus sp. wood has an increasing importance on supplying brazilian wood industry. The diminution of adult and large diameter trees supply deriving from natural tropical forests, became usual the production of wood on short rotation plantation, with considerable proportion of juvenil wood. Results from several researches have been demonstrated that MOE and mechanical strength are strongly affected by juvenile wood occurrence. This research was developed with the main objective of correlating dynamic modulus of elasticity (non-destructive ultrasound tests and MOE
Thermal compression modulus of polarized neutron matter
International Nuclear Information System (INIS)
Abd-Alla, M.
1990-05-01
We applied the equation of state for pure polarized neutron matter at finite temperature, calculated previously, to calculate the compression modulus. The compression modulus of pure neutron matter at zero temperature is very large and reflects the stiffness of the equation of state. It has a little temperature dependence. Introducing the spin excess parameter in the equation of state calculations is important because it has a significant effect on the compression modulus. (author). 25 refs, 2 tabs
Modeling of nano-reinforced polymer composites: Microstructure effect on Young’s modulus
DEFF Research Database (Denmark)
Peng, R.D.; Zhou, H.W.; Wang, H.W.
2012-01-01
” algorithm was developed in the ABAQUS Scripting Interface. In the computational studies, it was observed that the elastic modulus increases with the increasing the aspect ratio of nanoparticles. The thickness and properties of effective interface layers and the shape and degree of particles clustering have...
Effect of stress level on static young's modulus of certain structural materials
Energy Technology Data Exchange (ETDEWEB)
Vojtenko, A.F.; Skripnik, Yu.D.; Solov' eva, N.G.; Nadezhdin, G.N. (AN Ukrainskoj SSR, Kiev. Inst. Problem Prochnosti)
1982-11-01
Certain steels, titanium and aluminium alloys have been studied for their dynamic and static Young moduli. It is shown that a stress rise in materials to the level of microplastic strain realization results in a significant reduction of the static modulus of elasticity in the materials studied.
Detail of photo 7903109 stack of superconducting cables in the modulus measuring device
CERN PhotoLab
1979-01-01
The picture shows an assembly of insulated superconducting cables of the type used in the Po dipole magnet inserted in the elastic modulus measuring device (photos 7903547X and 7903169) in order to measures its mechanical properties under azimuthal compression. See also 7903547X, 7903169, 8307552X.
Effect of stress level on static young's modulus of certain structural materials
International Nuclear Information System (INIS)
Vojtenko, A.F.; Skripnik, Yu.D.; Solov'eva, N.G.; Nadezhdin, G.N.
1982-01-01
Certain steels, titanium and aluminium alloys have been studied for their dynamic and static Young moduli. It is shown that a stress rise in materials to the level of microplastic strain realization results in a significant reduction of the static modulus of elasticity in the materials studied
Resilient modulus for unbound granular materials and subgrade soils in Egypt
Directory of Open Access Journals (Sweden)
Mousa Rabah
2017-01-01
Full Text Available Mechanistic Empirical (ME pavement design methods started to gain attention especially the last couple of years in Egypt and the Middle East. One of the challenges facing the spread of these methods in Egypt is lack of advanced properties of local soil and asphalt, which are needed as input data in ME design. Resilient modulus (Mr for example is an important engineering property that expresses the elastic behavior of soil/unbound granular materials (UGMs under cyclic traffic loading for ME design. In order to overcome the scarcity of the resilient modulus data for soil/UGMs in Egypt, a comprehensive laboratory testing program was conducted to measure resilient modulus of typical UGMs and subgrade soils typically used in pavement construction in Egypt. The factors that affect the resilient modulus of soil/UGMs were reviewed, studied and discussed. Finally, the prediction accuracy of the most well-known Mr Prediction models for the locally investigated materials was investigated.
Variation of the Young's modulus with plastic strain applying to elastoplastic software
International Nuclear Information System (INIS)
Morestin, F.; Boivin, M.
1993-01-01
Work hardening of steel involves modifications of the elastic properties of the material, for instance, an increase of its yield stress. It may be also the cause of an appreciable decrease of the Young's modulus. This property decreases as plastic strain increases. Experiments with a microcomputer controlled tensile test machine indicated that diminution could reach more than 10% of the initial value, after only 5% of plastic strain. In spite of this fact, lots of elastoplastic softwares don't combine the decrease of the Young's modulus with plastification though it may involve obvious differences among results. As an application we have developed a software which computes the deformation of steel sheet in press forming, after springback. This software takes into account the decrease of the Young's modulus and its results are very close to experimental values. Quite arbitrarily, we noticed a recovery of the Young's modulus of plastified specimens after few days but not for all steels tested. (author)
Effect of van der Waals interactions on the structural and elastic properties of black phosphorus
DEFF Research Database (Denmark)
Appalakondaiah, S.; Vaitheeswaran, G.; Lebègue, S.
2012-01-01
constant is significantly larger than the C11 and C33 parameters, implying that black phosphorus is stiffer against strain along the a axis than along the b and c axes. From the calculated elastic constants, the mechanical properties, such as bulk modulus, shear modulus, Young's modulus, and Poisson...
Analytic approximations for the elastic moduli of two-phase materials
DEFF Research Database (Denmark)
Zhang, Z. J.; Zhu, Y. K.; Zhang, P.
2017-01-01
Based on the models of series and parallel connections of the two phases in a composite, analytic approximations are derived for the elastic constants (Young's modulus, shear modulus, and Poisson's ratio) of elastically isotropic two-phase composites containing second phases of various volume...
Amador, Carolina; Urban, Matthew W; Chen, Shigao; Greenleaf, James F
2012-03-07
Elasticity imaging methods have been used to study tissue mechanical properties and have demonstrated that tissue elasticity changes with disease state. In current shear wave elasticity imaging methods typically only shear wave speed is measured and rheological models, e.g. Kelvin-Voigt, Maxwell and Standard Linear Solid, are used to solve for tissue mechanical properties such as the shear viscoelastic complex modulus. This paper presents a method to quantify viscoelastic material properties in a model-independent way by estimating the complex shear elastic modulus over a wide frequency range using time-dependent creep response induced by acoustic radiation force. This radiation force induced creep method uses a conversion formula that is the analytic solution of a constitutive equation. The proposed method in combination with shearwave dispersion ultrasound vibrometry is used to measure the complex modulus so that knowledge of the applied radiation force magnitude is not necessary. The conversion formula is shown to be sensitive to sampling frequency and the first reliable measure in time according to numerical simulations using the Kelvin-Voigt model creep strain and compliance. Representative model-free shear complex moduli from homogeneous tissue mimicking phantoms and one excised swine kidney were obtained. This work proposes a novel model-free ultrasound-based elasticity method that does not require a rheological model with associated fitting requirements.
Kalita, Viktor M.; Snarskii, Andrei A.; Shamonin, Mikhail; Zorinets, Denis
2017-03-01
The influence of an external magnetic field on the static shear strain and the effective shear modulus of a magnetoactive elastomer (MAE) is studied theoretically in the framework of a recently introduced approach to the single-particle magnetostriction mechanism [V. M. Kalita et al., Phys. Rev. E 93, 062503 (2016), 10.1103/PhysRevE.93.062503]. The planar problem of magnetostriction in an MAE with magnetically soft inclusions in the form of a thin disk (platelet) having the magnetic anisotropy in the plane of this disk is solved analytically. An external magnetic field acts with torques on magnetic filler particles, creates mechanical stresses in the vicinity of inclusions, induces shear strain, and increases the effective shear modulus of these composite materials. It is shown that the largest effect of the magnetic field on the effective shear modulus should be expected in MAEs with soft elastomer matrices, where the shear modulus of the matrix is less than the magnetic anisotropy constant of inclusions. It is derived that the effective shear modulus is nonlinearly dependent on the external magnetic field and approaches the saturation value in magnetic fields exceeding the field of particle anisotropy. It is shown that model calculations of the effective shear modulus correspond to a phenomenological definition of effective elastic moduli and magnetoelastic coupling constants. The obtained theoretical results compare well with known experimental data. Determination of effective elastic coefficients in MAEs and their dependence on magnetic field is discussed. The concentration dependence of the effective shear modulus at higher filler concentrations has been estimated using the method of Padé approximants, which predicts that both the absolute and relative changes of the magnetic-field-dependent effective shear modulus will significantly increase with the growing concentration of filler particles.
Young’s Modulus and Poisson’s Ratio of Monolayer Graphyne
Directory of Open Access Journals (Sweden)
H. Rouhi
2013-09-01
Full Text Available Despite its numerous potential applications, two-dimensional monolayer graphyne, a novel form of carbon allotropes with sp and sp2 carbon atoms, has received little attention so far, perhaps as a result of its unknown properties. Especially, determination of the exact values of its elastic properties can pave the way for future studies on this nanostructure. Hence, this article describes a density functional theory (DFT investigation into elastic properties of graphyne including surface Young’s modulus and Poisson’s ratio. The DFT analyses are performed within the framework of generalized gradient approximation (GGA, and the Perdew–Burke–Ernzerhof (PBE exchange correlation is adopted. This study indicates that the elastic modulus of graphyne is approximately half of that of graphene due to its lower number of bonds.
Engber, Eamon; Teraoka, Jason; van Mantgem, Phillip J.
2017-01-01
Almost half of Redwood National Park is comprised of second-growth forests characterized by high stand density, deficient redwood composition, and low understory biodiversity. Typical structure of young redwood stands impedes the recovery of old-growth conditions, such as dominance of redwood (Sequoia sempervirens (D. Don) Endl.), distinct canopy layers and diverse understory vegetation. Young forests are commonly comprised of dense, even-aged Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) and redwood stump sprouts, with simple canopy structure and little understory development. Moreover, many of these young stands are believed to be vulnerable to disturbance in the form of drought, disease and fire. Silvicultural practices are increasingly being employed by conservation agencies to restore degraded forests throughout the coast redwood range; however, prescribed fire treatments are less common and potentially under-utilized as a restoration tool. We present an early synthesis from three separate management-scale prescribed fire projects at Redwood National Park spanning 1to 7 years post-treatment. Low intensity prescribed fire had minimal effect on overstory structure, with some mortality observed in trees smaller than 30 cm diameter. Moderate to high intensity fire may be required to reduce densities of larger Douglas-fir, the primary competitor of redwood in the Park’s second growth forests. Fine woody surface fuels fully recovered by 7 years post-burn, while recruitment of larger surface fuels was quite variable. Managers of coastal redwood ecosystems will benefit by having a variety of tools at their disposal for forest restoration and management.
Elastic properties of fly ash-stabilized mixes
Directory of Open Access Journals (Sweden)
Sanja Dimter
2015-12-01
Full Text Available Stabilized mixes are used in the construction of bearing layers in asphalt and concrete pavement structures. Two nondestructive methods: resonant frequency method and ultrasonic pulse velocity method, were used for estimation of elastic properties of fly ash–stabilized mixes. Stabilized mixes were designed containing sand from the river Drava and binder composed of different share of cement and fly ash. The aim of the research was to analyze the relationship between the dynamic modulus of elasticity determined by different nondestructive methods. Data showed that average value of elasticity modulus obtained by the ultrasound velocity method is lower than the values of elasticity modulus obtained by resonant frequency method. For further analysis and enhanced discussion of elastic properties of fly ash stabilized mixes, see Dimter et al. [1].
Elastic field of approaching dislocation loop in isotropic bimaterial
International Nuclear Information System (INIS)
Wu, Wenwang; Xu, Shucai; Zhang, Jinhuan; Xia, Re; Qian, Guian
2015-01-01
A semi-analytical solution is developed for calculating interface traction stress (ITS) fields due to elastic modulus mismatch across the interface plane of isotropic perfectly bounded bimaterial system. Based on the semi-analytical approaches developed, ITS is used to correct the bulk elastic field of dislocation loop within infinite homogenous medium, and to produce continuous displacement and stress fields across the perfectly-bounded interface. Firstly, calculation examples of dislocation loops in Al–Cu bimaterial system are performed to demonstrate the efficiency of the developed semi-analytical approach; Then, the elastic fields of dislocation loops in twinning Cu and Cu–Nb bimaterial are analyzed; Finally, the effect of modulus mismatch across interface plane on the elastic field of bimaterial system is investigated, it is found that modulus mismatch has a drastic impact on the elastic fields of dislocation loops within bimaterial system. (paper)
Clonal Spread in Second Growth Stands of Coast Redwood, Sequoia sempervirens
Vladimir Douhovnikoff; Richard S. Dodd
2007-01-01
Coast redwood (Sequoia sempervirens) is one of the rare conifers to reproduce successfully through clonal spread. The importance of this mode of reproduction in stand development is largely unknown. Understanding the importance of clonal spread and the spatial structure of clones is crucial for stand management strategies that would aim to maximize...
Reference conditions for old-growth redwood restoration on alluvial flats
Christa M. Dagley; John-Pascal. Berrill
2012-01-01
We quantified structural attributes in three alluvial flat old-growth coast redwood stands. Tree size parameters and occurrences of distinctive features (e.g., burls, goose pens) were similar between stands. Occurrence of distinctive features was greater among larger trees. Tree sizefrequency distributions conformed to a reverse-J diameter distribution. The range of...
Using Scientific Information to Develop Management Strategies for Commercial Redwood Timberlands
Jeffrey C. Barrett
2007-01-01
In 1999, PALCO (Pacific Lumber Company), a private landowner, and the state and federal governments agreed to implement a unique Habitat Conservation Plan (HCP) on 89,000 hectares of commercial redwood and Douglas-fir timberlands in Humboldt County, California. The aquatics portion of the PALCO HCP contains a set of "interim" conservation strategies developed...
Participation of gibberellin in the control of apical dominance in soybean and redwood
Energy Technology Data Exchange (ETDEWEB)
Ruddat, M.; Pharis, R.P.
1966-01-01
Loss of apical dominance in soybeans and redwood was increased when the plants were treated with the growth retardant AMO-1618. Simultaneous application of gibberellin reduced the number of elongating buds and promoted growth of the first or second uppermost auxillary bud, thus restoring apical dominance. It is concluded that gibberellin participates in the expression of apical dominance. 30 references, 2 tables.
Subdivide or silviculture: choices facing family forest owners in the redwood region
William Stewart; Shasta Ferranto; Gary Nakamura; Christy Getz; Lynn Huntsinger; Maggi. Kelly
2012-01-01
Families or family businesses own nearly all of the private redwood forestland in California. Family forest owners have practiced both subdivision and silviculture for decades but the dominant theme for most family owners is environmental stewardship. Parcel size is more important than expressed values as a predictor of resource management activities. All landowners...
Gregory A. Guisti
2012-01-01
A standardized, interactive, interview process was used with practicing Registered Professional Foresters asking a suite of questions to ascertain their management approaches to coast redwood (Sequoia sempervirens [D. Don] Endl.) stands that could best be transferred to other projects and lands interested in recruiting older forest...
The History of Redwood Records: Cultural and Economic Perspectives on a Feminist Subculture.
Lont, Cynthia M.
Using interviews and subcultural artifacts, such as inner sleeves of albums, this paper reports on the career of Holly Near and the history of Redwood Records, a label providing music to the lesbian-feminist subculture. First, the paper discusses the political and artistic avenues that were available to Near, the reasons she chose political music,…
Sudden Oak Death in redwood forests: vegetation dynamics in the wake of tanoak decline
Benjamin Ramage; Kevin O’Hara
2010-01-01
Numerous lines of inquiry have concluded that tanoak (Lithocarpus densiflorus) will continue to experience drastic population declines and may even disappear entirely from redwood (Sequoia sempervirens) forests as a result of the exotic disease sudden oak death (SOD) (Maloney and others 2005, McPherson and others 2005,...
Erin Clover Kelly; Joanna Di Tommaso; Arielle Weisgrau
2017-01-01
Californiaâs cap-and-trade carbon market has included forest offset projects, available to all private landowners across the United States. The redwood region has been at the forefront of the market, creating the earliest forest carbon projects. From carbon registries, we compiled a database of all forest carbon projects in the market, in order to determine...
Managing redwood ecosystems using Sudden Oak Death as a silvicultural tool
Frederick D. Euphrat
2015-01-01
In response to the wave of sudden oak death (SOD), caused by Phytophthora ramorum, sweeping the redwood forest ecosystems of California's North Coast, the role of foresters and other ecosystem managers is being tested. On Bear Flat Tree Farm, near Healdsburg, California, Forest, Soil & Water, Inc. (FSW) has conducted a multi-year,...
Rangewide Genetic Variation in Coast Redwood Populations at a Chloroplast Microsatellite Locus
Chris Brinegar
2012-01-01
Old growth and second growth populations of coast redwood (Sequoia sempervirens) were sampled at 10 locations throughout its range and analyzed at a highly variable chloroplast microsatellite locus. Very low FST values indicated that there was no significant genetic differentiation between adjacent old growth and second growth populations at each location. Genetic...
Edge effects and the effective size of old-growth coast redwood preserves
William H. Russell; Joe R. McBride; Ky Carnell
2000-01-01
Data were collected to determine the depth of influence of conditions created by clear-cut timber harvest on adjacent old-growth stands of coast redwood. Fourteen variables related to stand structure and composition, wildlife habitat, and physical environment exhibited significant correlation to distance from the timber harvest boundary. Results were applied to the...
Five years of monitoring infection and mortality in redwood tanoak forests
Richard C. Cobb; Shannon C. Lynch; Ross K. Meentemeyer; David M. Rizzo
2008-01-01
Rates of disease incidence and tree mortality in redwood-tanoak forests were determined by repeated sampling across a system of 120 plots at five long-term research sites from 2001 through 2006. Plots were located within the known geographic area of Phytophthora ramorum in California, ranging from Monterey to Sonoma counties. All overstory species...
Laboratory Tests of Bitumen Samples Elasticity
Ziganshin, E. R.; Usmanov, S. A.; Khasanov, D. I.; Khamidullina, G. S.
2018-05-01
This paper is devoted to the study of the elastic and acoustic properties of bitumen core samples. The travel velocities of the ultrasonic P- and S-waves were determined under in-situ simulation conditions. The resulting data were then used to calculate dynamic Young's modulus and Poisson's ratio. The authors studied the correlation between the elasticity and the permeability and porosity. In addition, the tests looked into how the acoustic properties had changed with temperature rise.
International Nuclear Information System (INIS)
Stan, G.; Krylyuk, S.; Davydov, A.V.; Vaudin, M.D.; Bendersky, L.A.; Cook, R.F.
2009-01-01
Quantitative measurements of the elastic modulus of nanosize systems and nanostructured materials are provided with great accuracy and precision by contact-resonance atomic force microscopy (CR-AFM). As an example of measuring the elastic modulus of nanosize entities, we used the CR-AFM technique to measure the out-of-plane indentation modulus of tellurium nanowires. A size-dependence of the indentation modulus was observed for the investigated tellurium nanowires with diameters in the range 20-150 nm. Over this diameter range, the elastic modulus of the outer layers of the tellurium nanowires experienced significant enhancement due to a pronounced surface stiffening effect. Quantitative estimations for the elastic moduli of the outer and inner parts of tellurium nanowires of reduced diameter are made with a core-shell structure model. Besides localized elastic modulus measurements, we have also developed a unique CR-AFM imaging capability to map the elastic modulus over a micrometer-scale area. We used this CR-AFM capability to construct indentation modulus maps at the junction between two adjacent facets of a tellurium microcrystal. The clear contrast observed in the elastic moduli of the two facets indicates the different surface crystallography of these facets.
Indentation of elastically soft and plastically compressible solids
Needleman, A.; Tvergaard, V.; Van der Giessen, E.
The effect of soft elasticity, i.e., a relatively small value of the ratio of Young's modulus to yield strength and plastic compressibility on the indentation of isotropically hardening elastic-viscoplastic solids is investigated. Calculations are carried out for indentation of a perfectly sticking
A two-crown finite element technique for the determination of tearing modulus
International Nuclear Information System (INIS)
Suo, X.Z.; Combescure, A.
1989-01-01
The importance of approach to the subject of crack instability for the design of structures containing cracks has increased considerably over the last few years. The tearing modulus theory recently enunciated by Paris and co-workers has emerged as one of the leading criterions for stable crack growth and for instability, and the estimation of T termed Tearing modulus in the theory has since been extensively investigated theoretically as well as experimentally. Analytical methods exist for calculating the tearing modulus of various crack configurations in simple-shaped structures under certain loading conditions. However, for arbitrary structures under general loading, more sophisticated calculation techniques are required. Extending the virtual crack extension method introduced independently by Hellen and Parks, a new numerical approach for calculating the tearing modulus is presented hereafter and put in a form suitable for the instability analysis of structures containing one single crack or several interacting cracks. As it is well-known that the calculation of the energy release rate in elasticity by the virtual crack extension method is related to a stiffness derivative to which only a small region around the crack tip has a contribution, the technique described in the paper shows that it would be reasonable to evaluate the tearing modulus, or rather, the second derivative of potential energy with respect to the crack length, by means of two stiffness derivative calculations in two crowns around the crack tip. In particular, when one crown is strictly included in another one, computation is largely curtailed at this point with some saving of computer time, but a very accurate value of tearing modulus is obtained. As an interesting consequence, an another expression of the tearing modulus is carried out. In Section 4: the classical tearing modulus is proved to be precisely equivalent to a line integral which is independent of integration path. Numerical example
Energy Technology Data Exchange (ETDEWEB)
Ni, Jennifer E [Chemical Engineering and Materials Science Department, Michigan State University, East Lansing, MI 48824 (United States); Case, Eldon D., E-mail: casee@egr.msu.edu [Chemical Engineering and Materials Science Department, Michigan State University, East Lansing, MI 48824 (United States); Khabir, Kristen N; Stewart, Ryan C [Chemical Engineering and Materials Science Department, Michigan State University, East Lansing, MI 48824 (United States); Wu, Chun-I; Hogan, Timothy P [Electrical and Computer Engineering Department, Michigan State University, East Lansing, MI 48824 (United States); Timm, Edward J [Mechanical Engineering Department, Michigan State University, East Lansing, MI 48824 (United States); Girard, Steven N; Kanatzidis, Mercouri G [Department of Chemistry, Northwestern University, Evanston, IL (United States)
2010-06-15
Two-phase PbTe-PbS materials, in which PbS is a nanostructured phase, are promising thermoelectric materials for the direct conversion of heat energy into electricity. In this study, a Vickers indentation mean hardness of 1.18 {+-} 0.09 GPa was measured for hot pressed specimens Pb{sub 0.95}Sn{sub 0.05}Te-PbS 8% while the mean hardness of cast specimens was 0.68 {+-} 0.07 GPa. The mean fracture toughness of the not pressed specimens was estimated as 0.35 {+-} 0.04 MPa m{sup 1/2} via Vickers indentation. Resonant Ultrasound Spectroscopy (RUS) measurements on hot pressed specimens gave mean values of Young's modulus, shear modulus and Poisson's ratio of 53.1 GPa, 21.4 GPa and 0.245, respectively while for the cast specimens the Young's and shear moduli were about 10% lower than for the hot pressed, with a mean value of Poisson's ratio of 0.245. The differences between the hardness and elastic moduli values for the cast and hot pressed specimens are discussed.
Influence of substrate modulus on gecko adhesion
Klittich, Mena R.; Wilson, Michael C.; Bernard, Craig; Rodrigo, Rochelle M.; Keith, Austin J.; Niewiarowski, Peter H.; Dhinojwala, Ali
2017-03-01
The gecko adhesion system fascinates biologists and materials scientists alike for its strong, reversible, glue-free, dry adhesion. Understanding the adhesion system’s performance on various surfaces can give clues as to gecko behaviour, as well as towards designing synthetic adhesive mimics. Geckos encounter a variety of surfaces in their natural habitats; tropical geckos, such as Gekko gecko, encounter hard, rough tree trunks as well as soft, flexible leaves. While gecko adhesion on hard surfaces has been extensively studied, little work has been done on soft surfaces. Here, we investigate for the first time the influence of macroscale and nanoscale substrate modulus on whole animal adhesion on two different substrates (cellulose acetate and polydimethylsiloxane) in air and find that across 5 orders of magnitude in macroscale modulus, there is no change in adhesion. On the nanoscale, however, gecko adhesion is shown to depend on substrate modulus. This suggests that low surface-layer modulus may inhibit the gecko adhesion system, independent of other influencing factors such as macroscale composite modulus and surface energy. Understanding the limits of gecko adhesion is vital for clarifying adhesive mechanisms and in the design of synthetic adhesives for soft substrates (including for biomedical applications and wearable electronics).
3-D FDTD simulation of shear waves for evaluation of complex modulus imaging.
Orescanin, Marko; Wang, Yue; Insana, Michael
2011-02-01
The Navier equation describing shear wave propagation in 3-D viscoelastic media is solved numerically with a finite differences time domain (FDTD) method. Solutions are formed in terms of transverse scatterer velocity waves and then verified via comparison to measured wave fields in heterogeneous hydrogel phantoms. The numerical algorithm is used as a tool to study the effects on complex shear modulus estimation from wave propagation in heterogeneous viscoelastic media. We used an algebraic Helmholtz inversion (AHI) technique to solve for the complex shear modulus from simulated and experimental velocity data acquired in 2-D and 3-D. Although 3-D velocity estimates are required in general, there are object geometries for which 2-D inversions provide accurate estimations of the material properties. Through simulations and experiments, we explored artifacts generated in elastic and dynamic-viscous shear modulus images related to the shear wavelength and average viscosity.
In situ determination of a rock mass modulus using a high resolution tiltmeter
Energy Technology Data Exchange (ETDEWEB)
Saleh, B.; Husein Malkawi, A.I. [University of Jordan, Amman (Jordan); Blum, P.A. [Universite Pierre et Marie Curie, 75 - Paris (France)
1996-04-01
A very sensitive, compact tiltmeter made of melted silica, developed for the measurement of small deformations of various civil engineering structures, was described. The instrument is capable of giving a continuous record and was used to establish a new approach to directly evaluating the in situ average elastic rock mass modulus. Such information is important in decision making during the design stages of large civil engineering works, such as dams, nuclear plant facilities, and underground structures. Five tiltmeters were installed on the facades of the Louvre in Paris to study the deformation induced by internal structural work and by the impact of the Paris metro traffic movement. The data was used to determine displacement using the Boussinesq equation. Results were consistent with typical elastic rock-mass modulus for the rock found in the museum`s foundations. 13 refs., 1 tab., 10 figs.
An autonomic self-healing organogel with a photo-mediated modulus
Xiong, Yubing
2016-11-15
A new method is described for fabricating autonomic, self-healing, deformable organogels. We combined imidazolium-based poly(ionic liquid) (PIL) and azobenzene-grafted poly(carboxylic acid) (PAA-Azo) in N,N-dimethyl formamide. Further, complexing PIL with unirradiated (trans) or irradiated (cis) PAA-Azo tuned the elastic modulus of the organogel. © 2016 The Royal Society of Chemistry.
An autonomic self-healing organogel with a photo-mediated modulus
Xiong, Yubing; Chen, Zhijun; Wang, Hong; Ackermann, Lisa Maria; Klapper, Markus; Butt, Hans Jü rgen; Wu, Si
2016-01-01
A new method is described for fabricating autonomic, self-healing, deformable organogels. We combined imidazolium-based poly(ionic liquid) (PIL) and azobenzene-grafted poly(carboxylic acid) (PAA-Azo) in N,N-dimethyl formamide. Further, complexing PIL with unirradiated (trans) or irradiated (cis) PAA-Azo tuned the elastic modulus of the organogel. © 2016 The Royal Society of Chemistry.
Tractor-logging costs and production in old-growth redwood forests
Kenneth N. Boe
1963-01-01
A cost accounting analysis of full-scale logging operations in old-growth redwood during 2 years revealed that it cost $12.24 per M bd. ft. (gross Scribner log scale) to get logs on trucks. Road development costs averaged another $5.19 per M bd. ft. Felling-bucking production was calculated by average tree d.b.h. Both skidding and loading outputs per hour were...
Structural relaxation monitored by instantaneous shear modulus
DEFF Research Database (Denmark)
Olsen, Niels Boye; Dyre, Jeppe; Christensen, Tage Emil
1998-01-01
time definition based on a recently proposed expression for the relaxation time, where G [infinity] reflects the fictive temperature. All parameters entering the reduced time were determined from independent measurements of the frequency-dependent shear modulus of the equilibrium liquid....
Effect of the Young modulus variability on the mechanical behaviour of a nuclear containment vessel
Energy Technology Data Exchange (ETDEWEB)
Larrard, T. de, E-mail: delarrard@lmt.ens-cachan.f [LMT-ENS Cachan, CNRS/UPMC/PRES UniverSud Paris (France); Colliat, J.B.; Benboudjema, F. [LMT-ENS Cachan, CNRS/UPMC/PRES UniverSud Paris (France); Torrenti, J.M. [Universite Paris-Est, LCPC (France); Nahas, G. [IRSN/DSR/SAMS/BAGS, Fontenay-aux-Roses (France)
2010-12-15
This study aims at investigating the influence of the Young modulus variability on the mechanical behaviour of a nuclear containment vessel in case of a loss of cooling agent accident and under the assumption of an elastic behaviour. To achieve this investigation, the Monte-Carlo Method is carried out thanks to a middleware which encapsulates the different components (random field generation, FE simulations) and enables calculations parallelisation. The main goal is to quantify the uncertainty propagation by comparing the maximal values of outputs of interest (orthoradial stress and Mazars equivalent strain) for each realisation of the considered random field with the ones obtained from a reference calculation taking into account uniform field (equal to the expected value of the random field). The Young modulus is supposed to be accurately represented by a weakly homogeneous random field and realisations are provided through its truncated Karhunen-Loeve expansion. This study reveals that the expected value for the maximal equivalent strain in the structure is more important when considering the Young modulus spatial variability than the value obtained from a deterministic approach with a uniform Young modulus field. The influence of the correlation length is investigated too. Finally it is shown that there is no correlation between the maximal values location of equivalent strain and the ones where the Young modulus extreme values are observed for each realisation.
Minimization of complementary energy to predict shear modulus of laminates with intralaminar cracks
International Nuclear Information System (INIS)
Giannadakis, K; Varna, J
2012-01-01
The most common damage mode and the one examined in this work is the formation of intralaminar cracks in layers of laminates. These cracks can occur when the composite structure is subjected to mechanical and/or thermal loading and eventually lead to degradation of thermo-elastic properties. In the present work, the shear modulus reduction due to cracking is studied. Mathematical models exist in literature for the simple case of cross-ply laminates. The in-plane shear modulus of a damaged laminate is only considered in a few studies. In the current work, the shear modulus reduction in cross-plies will be analysed based on the principle of minimization of complementary energy. Hashin investigated the in-plane shear modulus reduction of cross-ply laminates with cracks in inside 90-layer using this variational approach and assuming that the in-plane shear stress in layers does not depend on the thickness coordinate. In the present study, a more detailed and accurate approach for stress estimation is followed using shape functions for this dependence with parameters obtained by minimization. The results for complementary energy are then compared with the respective from literature and finally an expression for shear modulus degradation is derived.
Controlling elastic waves with small phononic crystals containing rigid inclusions
Peng, Pai
2014-05-01
We show that a two-dimensional elastic phononic crystal comprising rigid cylinders in a solid matrix possesses a large complete band gap below a cut-off frequency. A mechanical model reveals that the band gap is induced by negative effective mass density, which is affirmed by an effective medium theory based on field averaging. We demonstrate, by two examples, that such elastic phononic crystals can be utilized to design small devices to control low-frequency elastic waves. One example is a waveguide made of a two-layer anisotropic elastic phononic crystal, which can guide and bend elastic waves with wavelengths much larger than the size of the waveguide. The other example is the enhanced elastic transmission of a single-layer elastic phononic crystal loaded with solid inclusions. The effective mass density and reciprocal of the modulus of the single-layer elastic phononic crystal are simultaneously near zero. © CopyrightEPLA, 2014.
Remarks on orthotropic elastic models applied to wood
Directory of Open Access Journals (Sweden)
Nilson Tadeu Mascia
2006-09-01
Full Text Available Wood is generally considered an anisotropic material. In terms of engineering elastic models, wood is usually treated as an orthotropic material. This paper presents an analysis of two principal anisotropic elastic models that are usually applied to wood. The first one, the linear orthotropic model, where the material axes L (Longitudinal, R( radial and T(tangential are coincident with the Cartesian axes (x, y, z, is more accepted as wood elastic model. The other one, the cylindrical orthotropic model is more adequate of the growth caracteristics of wood but more mathematically complex to be adopted in practical terms. Specifically due to its importance in wood elastic parameters, this paper deals with the fiber orientation influence in these models through adequate transformation of coordinates. As a final result, some examples of the linear model, which show the variation of elastic moduli, i.e., Young´s modulus and shear modulus, with fiber orientation are presented.
Elastic representation surfaces of unidirectional graphite/epoxy composites
International Nuclear Information System (INIS)
Kriz, R.D.; Ledbetter, H.M.
1985-01-01
Unidirectional graphite/epoxy composites exhibit high elastic anisotropy and unusual geometrical features in their elastic-property polar diagrams. From the five-component transverse-isotropic elastic-stiffness tensor we compute and display representation surfaces for Young's modulus, torsional modulus, linear compressibility, and Poisson's ratios. Based on Christoffel-equation solutions, we describe some unusual elastic-wave-surface topological features. Musgrave considered in detail the differences between phase-velocity and group-velocity surfaces arising from high elastic anisotropy. For these composites, we find effects similar to, but more dramatic than, Musgrave's. Some new, unexpected results for graphite/epoxy include: a shear-wave velocity that exceeds a longitudinal velocity in the plane transverse to the fiber; a wave that changes polarization character from longitudinal to transverse as the propagation direction sweeps from the fiber axis to the perpendicular axis
Directory of Open Access Journals (Sweden)
Kevin L. O’Hara
2017-04-01
Full Text Available Coast redwood (Sequoia sempervirens (Lamb. ex. D. Don Endl. is unique among conifer species because of its longevity, the great sizes of individual trees, and its propensity to reproduce through sprouts. Timber harvesting in the native redwood range along the coast of the western United States has necessitated restoration aimed to promote old forest structures to increase the total amount of old forest, the connectivity between old forests, and to enhance the resiliency of these ecosystems. After disturbance or harvest, healthy redwood stumps sprout vigorously, often producing dozens of sprouts within two years of disturbance. These sprouts form highly aggregated spatial patterns because they are clustered around stumps that may number less than 50 ha−1. Thinning of sprouts can accelerate individual tree growth, providing an effective restoration strategy to accelerate formation of large trees and old forest structures or increase stand growth for timber production. However, management, including restoration activities, is a contentious issue throughout the native range of redwood because of the history of overexploitation of this resource and perceptions that overexploitation is continuing. This paper reviews the science of early stand dynamics in coast redwood and their implications for restoration and other silvicultural strategies.
Vliet, Jurg; Wel, Steven; Dowd, Dara
2011-01-01
While it's always been possible to run Java applications on Amazon EC2, Amazon's Elastic Beanstalk makes the process easier-especially if you understand how it works beneath the surface. This concise, hands-on book not only walks you through Beanstalk for deploying and managing web applications in the cloud, you'll also learn how to use this AWS tool in other phases of development. Ideal if you're a developer familiar with Java applications or AWS, Elastic Beanstalk provides step-by-step instructions and numerous code samples for building cloud applications on Beanstalk that can handle lots
Resilient modulus of black cotton soil
Directory of Open Access Journals (Sweden)
K.H. Mamatha
2017-03-01
Full Text Available Resilient modulus (MR values of pavement layers are the basic input parameters for the design of pavements with multiple layers in the current mechanistic empirical pavement design guidelines. As the laboratory determination of resilient modulus is costly, time consuming and cumbersome, several empirical models are developed for the prediction of resilient modulus for different regions of the world based on the database of resilient modulus values of local soils. For use of these relationships there is a need to verify the suitability of these models for local conditions. Expansive clay called black cotton soil (BC soil is found in several parts of India and is characterized by low strength and high compressibility. This soil shows swell – shrink behaviour upon wetting and drying and are problematic. The BC soil shows collapse behaviour on soaking and therefore the strength of the soil needs to be improved. Additive stabilization is found to be very effective in stabilizing black cotton soils and generally lime is used to improve the strength and durability of the black cotton soil. In this paper, the results of repeated load tests on black cotton soil samples for the determination of MR under soaked and unsoaked conditions at a relative compaction levels of 100% and 95% of both standard and modified proctor conditions are reported. The results indicate that the black cotton soil fails to meet the density requirement of the subgrade soil and shows collapse behaviour under soaked condition. To overcome this, lime is added as an additive to improve the strength of black cotton soil and repeated load tests were performed as per AASHTO T 307 - 99 for MR determination. The results have shown that the samples are stable under modified proctor condition with MR values ranging from 36 MPa to 388 MPa for a lime content of 2.5% and curing period ranging from 7 to 28 days. Also, it is observed that, the CBR based resilient modulus is not in agreement
Theoretical study of the elastic properties of titanium nitride
Institute of Scientific and Technical Information of China (English)
Jingdong CHEN; Yinglu ZHAO; Benhai YU; Chunlei WANG; Deheng SHI
2009-01-01
The equilibrium lattice parameter, relative volume V/Vo, elastic constants Cij, and bulk modulus of titanium nitride are successfully obtained using the ab initio plane-wave pseudopotential (PW-PP) method within the framework of density functional theory. The quasi-harmonic Debye model, using a set of total energy vs molar volume obtained with the PW-PP method, is applied to the study of the elastic properties and vibrational effects. We analyze the relationship between the bulk modulus and temperature up to 2000 K and obtain the relationship between bulk modulus B and pressure at different temperatures. It is found that the bulk modulus B increases monotonously with increasing pressure and decreases with increasing temperature. Moreover, the Debye temperature is determined from the non-equilibrium Gibbs func-tions.
Fibonacci difference sequence spaces for modulus functions
Directory of Open Access Journals (Sweden)
Kuldip Raj
2015-05-01
Full Text Available In the present paper we introduce Fibonacci difference sequence spaces l(F, Ƒ, p, u and l_∞(F, Ƒ, p, u by using a sequence of modulus functions and a new band matrix F. We also make an effort to study some inclusion relations, topological and geometric properties of these spaces. Furthermore, the alpha, beta, gamma duals and matrix transformation of the space l(F, Ƒ, p, u are determined.
Theory of thermal expansivity and bulk modulus
International Nuclear Information System (INIS)
Kumar, Munish
2005-01-01
The expression for thermal expansivity and bulk modulus, claimed by Shanker et al. to be new [Physica B 233 (1977) 78; 245 (1998) 190; J. Phys. Chem. Solids 59 (1998) 197] are compared with the theory of high pressure-high temperature reported by Kumar and coworkers. It is concluded that the Shanker formulation and the relations based on this are equal to the approach of Kumar et al. up to second order
Burial stress and elastic strain of carbonate rocks
DEFF Research Database (Denmark)
Fabricius, Ida Lykke
2014-01-01
Burial stress on a sediment or sedimentary rock is relevant for predicting compaction or failure caused by changes in, e.g., pore pressure in the subsurface. For this purpose, the stress is conventionally expressed in terms of its effect: “the effective stress” defined as the consequent elastic...... strain multiplied by the rock frame modulus. We cannot measure the strain directly in the subsurface, but from the data on bulk density and P‐wave velocity, we can estimate the rock frame modulus and Biot's coefficient and then calculate the “effective vertical stress” as the total vertical stress minus...... the product of pore pressure and Biot's coefficient. We can now calculate the elastic strain by dividing “effective stress” with the rock frame modulus. By this procedure, the degree of elastic deformation at a given time and depth can be directly expressed. This facilitates the discussion of the deformation...
Measurement of elastic modules of structural ceramic by acoustic resonance
International Nuclear Information System (INIS)
Ahn, Bong Young; Lee Seong Suck; Kim, Young Gil
1993-01-01
Elastic moduli of structural ceramic materials, Al 2 O 3 , SiC, Si 3 N 4 , were measured by acoustic resonance method. Young's modulus, shear modulus, and Poisson's ratio were calculated from the torsional and flexural resonant frequencies, densities, and the dimensions of the specimen. The results by acoustic resonance method were compared with the results by ultrasonic method and the differences were less than 4%.
Adler, Thomas A.
1996-01-01
The invention pertains a method of determining elastic and plastic mechanical properties of ceramics, intermetallics, metals, plastics and other hard, brittle materials which fracture prior to plastically deforming when loads are applied. Elastic and plastic mechanical properties of ceramic materials are determined using spherical indenters. The method is most useful for measuring and calculating the plastic and elastic deformation of hard, brittle materials with low values of elastic modulus to hardness.
International Nuclear Information System (INIS)
Medkour, Y.; Roumili, A.; Maouche, D.; Saoudi, A.; Louail, L.
2012-01-01
Highlights: ► Single crystal elastic constants C 11 , C 12 and C 44 were calculated. ► Elastic moduli for polycrystalline aggregate were obtained. ► Increasing the atomic number of A element reduces B, G′, Y and v. ► Mn 3 AlC has a high melting point and light weight. - Abstract: First principle calculations were made to investigate the elastic properties of Mn 3 AC antiperovskites, A = Zn, Al, Ga, In, Tl, Ge and Sn. The estimated equilibrium lattice parameters are in agreement with the experimental ones. From the single crystal elastic constants we have calculated the polycrystalline elastic moduli: the bulk modulus B, shear modulus G, tetragonal shear modulus G′, Young’s modulus Y, Cauchy’s pressure CP, Poisson’s ratio v, elastic anisotropy factor and Pugh’s criterion G/B. Using Debye’s approximation we have deduced the elastic wave velocities and Debye’s temperature.
Elastic spheres can walk on water.
Belden, Jesse; Hurd, Randy C; Jandron, Michael A; Bower, Allan F; Truscott, Tadd T
2016-02-04
Incited by public fascination and engineering application, water-skipping of rigid stones and spheres has received considerable study. While these objects can be coaxed to ricochet, elastic spheres demonstrate superior water-skipping ability, but little is known about the effect of large material compliance on water impact physics. Here we show that upon water impact, very compliant spheres naturally assume a disk-like geometry and dynamic orientation that are favourable for water-skipping. Experiments and numerical modelling reveal that the initial spherical shape evolves as elastic waves propagate through the material. We find that the skipping dynamics are governed by the wave propagation speed and by the ratio of material shear modulus to hydrodynamic pressure. With these insights, we explain why softer spheres skip more easily than stiffer ones. Our results advance understanding of fluid-elastic body interaction during water impact, which could benefit inflatable craft modelling and, more playfully, design of elastic aquatic toys.
Prediction study of structural, elastic and electronic properties of FeMP (M = Ti, Zr, Hf) compounds
Tanto, A.; Chihi, T.; Ghebouli, M. A.; Reffas, M.; Fatmi, M.; Ghebouli, B.
2018-06-01
First principles calculations are applied in the study of FeMP (M = Ti, Zr, Hf) compounds. We investigate the structural, elastic, mechanical and electronic properties by combining first-principles calculations with the CASTEP approach. For ideal polycrystalline FeMP (M = Ti, Zr, Hf) the shear modulus, Young's modulus, Poisson's ratio, elastic anisotropy indexes, Pugh's criterion, elastic wave velocities and Debye temperature are also calculated from the single crystal elastic constants. The shear anisotropic factors and anisotropy are obtained from the single crystal elastic constants. The Debye temperature is calculated from the average elastic wave velocity obtained from shear and bulk modulus as well as the integration of elastic wave velocities in different directions of the single crystal.
Visualising elastic anisotropy: theoretical background and computational implementation
Nordmann, J.; Aßmus, M.; Altenbach, H.
2018-02-01
In this article, we present the technical realisation for visualisations of characteristic parameters of the fourth-order elasticity tensor, which is classified by three-dimensional symmetry groups. Hereby, expressions for spatial representations of uc(Young)'s modulus and bulk modulus as well as plane representations of shear modulus and uc(Poisson)'s ratio are derived and transferred into a comprehensible form to computer algebra systems. Additionally, we present approaches for spatial representations of both latter parameters. These three- and two-dimensional representations are implemented into the software MATrix LABoratory. Exemplary representations of characteristic materials complete the present treatise.
Elastic properties of silicon nitride ceramics reinforced with graphene nanofillers
Czech Academy of Sciences Publication Activity Database
Seiner, Hanuš; Ramírez, C.; Koller, M.; Sedlák, Petr; Landa, Michal; Miranzo, P.; Belmonte, M.; Osendí, M. I.
2015-01-01
Roč. 87, December (2015), s. 675-680 ISSN 0264-1275 R&D Projects: GA ČR GB14-36566G Institutional support: RVO:61388998 Keywords : multilayer graphene * graphene oxide (GO) * silicon nitride * elastic constants * elastic modulus * shear modulus Subject RIV: JI - Composite Materials Impact factor: 3.997, year: 2015 http://www.sciencedirect.com/science/article/pii/S0264127515302938/pdfft?md5=571e00fd7f976e9b66ed789ae2a868b2&pid=1-s2.0-S0264127515302938-main.pdf
Elasticity Constants of a Two-Phase Tungsten Thin Film
Directory of Open Access Journals (Sweden)
Mohamed Fares Slim
2018-05-01
Full Text Available The IET was used to determine the macroscopic elasticity constants of the multiphase coating. In order to determine the macroscopic elasticity constants of the film firstly, a critical assessment of Young’s modulus determination was done by comparing all the models proposed in the literature. The best model was identified and a study was performed to identify and quantify the most influent factors on the global uncertainty. Secondly, an enhanced formulation to determine the shear modulus of coating by IET was developed. The methodology was applied on a tungsten thin film deposited by DC magnetron sputtering.
International Nuclear Information System (INIS)
Leader, Elliot
1991-01-01
With very few unexplained results to challenge conventional ideas, physicists have to look hard to search for gaps in understanding. An area of physics which offers a lot more than meets the eye is elastic and diffractive scattering where particles either 'bounce' off each other, emerging unscathed, or just graze past, emerging relatively unscathed. The 'Blois' workshops provide a regular focus for this unspectacular, but compelling physics, attracting highly motivated devotees
Probing hysteretic elasticity in weakly nonlinear materials
Energy Technology Data Exchange (ETDEWEB)
Johnson, Paul A [Los Alamos National Laboratory; Haupert, Sylvain [UPMC UNIV PARIS; Renaud, Guillaume [UPMC UNIV PARIS; Riviere, Jacques [UPMC UNIV PARIS; Talmant, Maryline [UPMC UNIV PARIS; Laugier, Pascal [UPMC UNIV PARIS
2010-12-07
Our work is aimed at assessing the elastic and dissipative hysteretic nonlinear parameters' repeatability (precision) using several classes of materials with weak, intermediate and high nonlinear properties. In this contribution, we describe an optimized Nonlinear Resonant Ultrasound Spectroscopy (NRUS) measuring and data processing protocol applied to small samples. The protocol is used to eliminate the effects of environmental condition changes that take place during an experiment, and that may mask the intrinsic elastic nonlinearity. As an example, in our experiments, we identified external temperature fluctuation as a primary source of material resonance frequency and elastic modulus variation. A variation of 0.1 C produced a frequency variation of 0.01 %, which is similar to the expected nonlinear frequency shift for weakly nonlinear materials. In order to eliminate environmental effects, the variation in f{sub 0} (the elastically linear resonance frequency proportional to modulus) is fit with the appropriate function, and that function is used to correct the NRUS calculation of nonlinear parameters. With our correction procedure, we measured relative resonant frequency shifts of 10{sup -5} , which are below 10{sup -4}, often considered the limit to NRUS sensitivity under common experimental conditions. Our results show that the procedure is an alternative to the stringent control of temperature often applied. Applying the approach, we report nonlinear parameters for several materials, some with very small nonclassical nonlinearity. The approach has broad application to NRUS and other Nonlinear Elastic Wave Spectroscopy approaches.
The elastic response of composite materials
International Nuclear Information System (INIS)
Laws, N.
1980-01-01
The theory of linear elasticity is used to study the elastic response of composite materials. The main concern is the prediction of overall moduli. Some attention is paid to the problem of deciding upon when the idea of an overall modulus is meaningful. In addition it is shown how to calculate some rigorous bounds on the overall moduli, and some predictions of the self-consistent method are discussed. The paper mainly concentrates on isotropic dispersions of spheres, unidirectional fibre-reinforced materials and laminates. (author)
Asphalt mix characterization using dynamic modulus and APA testing.
2005-11-01
final report summarizes two research efforts related to asphalt mix characterization: dynamic modulus and Asphalt Pavement Analyzer testing. One phase of the research consisted of a laboratory-based evaluation of dynamic modulus of Oregon dense-grade...
Elastic properties of synthetic materials for soft tissue modeling
International Nuclear Information System (INIS)
Mansy, H A; Grahe, J R; Sandler, R H
2008-01-01
Mechanical models of soft tissue are useful for studying vibro-acoustic phenomena. They may be used for validating mathematical models and for testing new equipment and techniques. The objective of this study was to measure density and visco-elastic properties of synthetic materials that can be used to build such models. Samples of nine different materials were tested under dynamic (0.5 Hz) compressive loading conditions. The modulus of elasticity of the materials was varied, whenever possible, by adding a softener during manufacturing. The modulus was measured over a nine month period to quantify the effect of ageing and softener loss on material properties. Results showed that a wide range of the compression elasticity modulus (10 to 1400 kPa) and phase (3.5 0 -16.7 0 ) between stress and strain were possible. Some materials tended to exude softener over time, resulting in a weight loss and elastic properties change. While the weight loss under normal conditions was minimal in all materials (<3% over nine months), loss under accelerated weight-loss conditions can reach 59%. In the latter case an elasticity modulus increase of up to 500% was measured. Key advantages and limitations of candidate materials were identified and discussed
Summary of watershed conditions in the vicinity of Redwood National Park, California
Janda, Richard J.
1977-01-01
The Redwood Creek Unit of Redwood National Park is located in the downstream end of an exceptionally rapidly eroding drainage basin. Spatial distribution and types of erosional landforms, observed in the field and on time-sequential aerial photographs, measured sediment loads, and the lithologic heterogeneity of streambed materials indicated (1) that sediment discharges reflect a complex suite of natural and man-induced mass movement and fluvial erosion processes operating on a geologically heterogeneous, naturally unstable terrain, and (2) that although infrequent exceptionally intense storms control the timing and general magnitude of major erosion events, the loci, types, and amounts of erosion occurring during those events are substantially influence by land use. Erosional impacts of past timber harvest in the Redwood Creek basin reflect primarily the cumulative impact of many small erosion problems caused not so much by removal. Recently modified riparian and aquatic environments reflect stream channel adjustments to recently increased water and sediment discharges, and are classified by the National Park Service as damaged resources because the modifications reflect, in part, unnatural causes. Newly strengthened State regulations and cooperative review procedures result in proposed timber harvest plans being tailored to specific site conditions, as well as smaller, more dispersed harvest units and more sophisticated attempts at minimizing ground-surface disruption than those used in most previous timber harvesting in this basin. However, application of improved timber harvest technology alone will not assure protection of park resources. Much remaining intact residual commercial old-growth timber is on hillslopes that are steeper, wetter, more susceptible to landsliding, and more nearly adjacent to major stream channels than most of the previously harvested hillslopes in the lower Redwood Creek basin. Moreover, natural debris barriers along streams flowing
Effect of Preservative Treatment on Fungal Colonization of Teak, Redwood, and Western Red Cedar
DEFF Research Database (Denmark)
Cabrera Orozco, Yohanna; Freitag, F.; Morrell, Jeffrey J.
Fungal flora present in preservative treated samples or non-treated samples from sapwood and heartwood of teak, western red cedar, redwood, and southern yellow pine was assessed after 6 to 18 months of exposure near Hilo, Hawaii. The objectives were to compare fungal composition and diversity...... between treated and non-treated samples, and to examine the use of molecular techniques for assessing fungal community structure in a ground-proximity-test located in Hilo, Hawaii. Fungi were recovered in culture after 6, 12, or 18 months, yielding 178 unique DNA sequences that represented 85 taxa...
Climatic and physiological effects on leaf and tree-ring stable isotopes in California redwoods
Ambrose, A. R.; Baxter, W.; Wong, C.; Dawson, T. E.; Carroll, A.; Voelker, S.
2016-12-01
Variation in the stable isotope composition of organic matter can provide important information about environmental change and biological responses to it. We analyzed the stable carbon (d13C) and oxygen (d18O) isotope ratios of leaves and of the cellulose from individual tree-rings of California's two redwood species to examine how these trees have responded to environmental variation and change in both time and space. Analyses of leaf d13C for both coast redwood (Sequoia sempervirens) and giant sequoia (Sequoiadendron giganteum) from throughout their geographical ranges show a marked gradient with tree height for trees of all sizes and ages but no clear difference among species or populations. The gradient is best explained by tree response to changes in both microenvironment and physiology that are known to change with height. In contrast, leaf d18O for both species showed no clear relationship with height but very clear differences between species and populations with giant sequoia displaying a much stronger inferred leaf-level response to the higher evaporative conditions present in the Sierra Nevada mountains as compared to the coast. Both species showed population-level differences with the driest and warmest sites most distinct from all of the others. Intra-annual analyses of d13C and d18O in tree-rings over a 21-year period (1974-1994) were also used to explore how climate and tree response to climate was recorded for both species. These analyses revealed unique (local) climatic effects and response to the climate for each species and population of both redwood species. Most pronounced was a significant increase in intrinsic Water Use Efficiency (iWUE) derived from d13C data over the study period in both species, and a distinct d18O response in relation to drought (e.g. 1976/1977) and to warmer days and nights and above-average precipitation (e.g., 1982-1985). Patterns of co-variation in d13C and d18O in both species suggest that during dry and also warm
Export of fine particulate organic carbon from redwood-dominated catchments
Madej, Mary Ann
2015-01-01
Recently, researchers have recognized the significant role of small mountainous river systems in the transport of carbon from terrestrial environments to the ocean, and the scale of such studies have ranged from channel bed units to continents. In temperate zones, these mountain river systems commonly drain catchments that are largely forested. However, the magnitude of carbon export from rivers draining old-growth redwood forests has not been evaluated to date. Old-growth redwood stands support some of the largest quantities of biomass in the world, up to 350 000 Mg of stem biomass km-2 and soil organic carbon can reach 46 800 Mg km-2. In north coastal California, suspended sediment samples were collected at three gaging stations for two to four years on streams draining old-growth redwood forests. Carbon content, determined through loss-on-ignition tests, was strongly correlated with turbidity, and continuous turbidity records from the gaging stations were used to estimate annual carbon exports of 1 · 6 to 4 · 2 Mg km-2 yr-1. These values, representing 13 to 33% of the suspended sediment load, are some of the highest percentages reported in the global literature. The fraction of organic carbon as part of the suspended sediment load decreased with discharge, but reached an asymptote of 5 to 10% at flows 10 to 20 times the mean annual flows. Although larger rivers in this region exhibit high sediment yields (up to 3600 Mg km-2 yr-1), mainly attributed to high rates of uplift, mass movement, and timber harvest, the small pristine streams in this study have sediment yields of only 8 to 100 Mg km-2 yr-1. Because the current extent of old-growth redwood stands is less than 5% of its pre-European-settlement distribution, the present organic carbon signature in suspended sediment loads in this region is likely different from that in the early 20th century. Published 2015. This article is a U.S. Government work and is in the public
Multiphase composites with extremal bulk modulus
DEFF Research Database (Denmark)
Gibiansky, L. V.; Sigmund, Ole
2000-01-01
are described. Most of our new results are related to the two-dimensional problem. A numerical topology optimization procedure that solves the inverse homogenization problem is adopted and used to look for two-dimensional three-phase composites with a maximal effective bulk modulus. For the combination...... isotropic three-dimensional three-phase composites with cylindrical inclusions of arbitrary cross-sections (plane strain problem) or transversely isotropic thin plates (plane stress or bending of plates problems). (C) 2000 Elsevier Science Ltd. All rights reserved....
Young Modulus of Crystalline Polyethylene from ab Initio Molecular Dynamics
Hageman, J.C.L.; Meier, Robert J.; Heinemann, M.; Groot, R.A. de
1997-01-01
The Young modulus for crystalline polyethylene is calculated using ab initio molecular dynamics based on density functional theory in the local density approximation (DFT-LDA). This modulus, which can be seen as the ultimate value for the Young modulus of polyethylene fibers, is found to be 334 GPa.
Low-temperature monocrystal elastic constants of Fe-19Cr-10Ni
International Nuclear Information System (INIS)
Ledbetter, H.M.
1984-01-01
By a pulse-echo-overlap ultrasonic method, we determined the monocrystal elastic constants (C 11 , C 12 , C 44 ) of an Fe-19Cr-10Ni alloy between 295 and 4 K. In composition this laboratory alloy approximates a technological austenitic stainless steel: AISI 304. Many previous studies on polycrystalline steels found a low-temperature magnetic phase transition that affects physical properties, including elastic constants. At the transition, anomalies occur in all polycrystal elastic constants: Young's modulus, shear modulus, bulk modulus, and Poisson's ratio. The present study found that the transition, near 50 K, does not affect one monocrystal elastic constant: C 44 , the resistance to shear on a (100) plane in a [100]-type direction. We interpret this new observation from the viewpoint of a Born-type lattice model. Also, we comment about the relationship between the elastic-constant changes and the low-temperature magnetic state
Model-Based Reconstructive Elasticity Imaging Using Ultrasound
Directory of Open Access Journals (Sweden)
Salavat R. Aglyamov
2007-01-01
Full Text Available Elasticity imaging is a reconstructive imaging technique where tissue motion in response to mechanical excitation is measured using modern imaging systems, and the estimated displacements are then used to reconstruct the spatial distribution of Young's modulus. Here we present an ultrasound elasticity imaging method that utilizes the model-based technique for Young's modulus reconstruction. Based on the geometry of the imaged object, only one axial component of the strain tensor is used. The numerical implementation of the method is highly efficient because the reconstruction is based on an analytic solution of the forward elastic problem. The model-based approach is illustrated using two potential clinical applications: differentiation of liver hemangioma and staging of deep venous thrombosis. Overall, these studies demonstrate that model-based reconstructive elasticity imaging can be used in applications where the geometry of the object and the surrounding tissue is somewhat known and certain assumptions about the pathology can be made.
Measurement of ultimate tensile strength and Young modulus in LYSO scintillating crystals
Energy Technology Data Exchange (ETDEWEB)
Scalise, Lorenzo, E-mail: l.scalise@univpm.it [Dipartimento di Meccanica, Universita Politecnica delle Marche, Via Brecce Bianche, 60131 Ancona (Italy); Rinaldi, Daniele [Dipartimento di Fisica e Ingegneria dei Materiali e del Territorio, Universita Politecnica delle Marche, Via Brecce Bianche, 60131 Ancona (Italy); Istituto Nazionale di Fisica Nucleare, Section of Perugia (Italy); Davi, Fabrizio [Dipartimento di Architettura Costruzioni e Strutture, Universita Politecnica delle Marche, Via Brecce Bianche, 60131 Ancona (Italy); Paone, Nicola [Dipartimento di Meccanica, Universita Politecnica delle Marche, Via Brecce Bianche, 60131 Ancona (Italy)
2011-10-21
Scintillating crystals are employed in high energy physics, in medical imaging, diagnostic and security. Two mechanical properties of lutetium-yttrium oxyorthosilicate cerium-doped Lu{sub 2(1-x)}Y{sub 2x}SiO{sub 5}:Ce with x=0.1 (LYSO) crystals have been measured: the ultimate tensile stress ({sigma}{sub UTS}) and the Young elastic modulus (E). Measurements are made by means of a 4-points loading device and the experimental results account for an elastic-brittle stress-strain relation, which depends heavily on the specimen preparation and the material defects. {sigma}{sub UTS} along the [0 1 0] tensile direction ranges within 68.14 and 115.61 MPa, which, in the lowest case, is more than twice with respect to those measured for PbWO{sub 4} (PWO), exhibiting a marked difference between the annealed and the not-annealed samples. The mean elastic modulus (E), along the same direction, is E=1.80x10{sup 11} ({+-}2.15x10{sup 10}) N/m{sup 2}, with lower dispersion respect to UTS data. This type of analysis and study can be included into quality control procedures of crystals, based on samples taken out of production; such procedures can be established for industrial processing of crystals aimed to the high energy physics (calorimeters) and medical imaging (PET, etc.) applications.
Dynamic modulus of nanosilica modified porous asphalt
Arshad, A. K.; Masri, K. A.; Ahmad, J.; Samsudin, M. S.
2017-11-01
Porous asphalt (PA) is a flexible pavement layer with high interconnected air void contents and constructed using open-graded aggregates. Due to high temperature environment and increased traffic volume in Malaysia, PA may have deficiencies particularly in rutting and stiffness of the mix. A possible way to improve these deficiencies is to improve the asphalt binder used. Binder is normally modified using polymer materials to improve its properties. However, nanotechnology presently is being gradually used for asphalt modification. Nanosilica (NS), a byproduct of rice husk and palm oil fuel ash is used as additive in this study. The aim of this study is to enhance the rutting resistance and stiffness performance of PA using NS. This study focused on the performance of PA in terms of dynamic modulus with the addition of NS modified binder to produce better and more durable PA. From the result of Dynamic SPT Test, it shows that the addition of NS was capable in enhancing the stiffness and rutting resistance of PA. The addition of NS also increase the dynamic modulus value of PA by 50%.
Temperature dependence of grain boundary free energy and elastic constants
International Nuclear Information System (INIS)
Foiles, Stephen M.
2010-01-01
This work explores the suggestion that the temperature dependence of the grain boundary free energy can be estimated from the temperature dependence of the elastic constants. The temperature-dependent elastic constants and free energy of a symmetric Σ79 tilt boundary are computed for an embedded atom method model of Ni. The grain boundary free energy scales with the product of the shear modulus times the lattice constant for temperatures up to about 0.75 the melting temperature.
The instantaneous shear modulus in the shoving model
DEFF Research Database (Denmark)
Dyre, J. C.; Wang, W. H.
2012-01-01
We point out that the instantaneous shear modulus G∞ of the shoving model for the non-Arrhenius temperature dependence of viscous liquids’ relaxation time is the experimentally accessible highfrequency plateau modulus, not the idealized instantaneous affine shear modulus that cannot be measured....... Data for a large selection of metallic glasses are compared to three different versions of the shoving model. The original shear-modulus based version shows a slight correlation to the Poisson ratio, which is eliminated by the energy-landscape formulation of the model in which the bulk modulus plays...
Christopher E. DeForest
1999-01-01
There are many parallels between the 1978 legislation to expand Redwood National Park and the Northwest Forest Plan, which together with the Northwest Economic Adjustment Initiative formed the 1993 Pacific Northwest Initiative. In both situations, the Federal Government sought to promote retraining for displaced workers, to undertake watershed assessment and...
Kevin L. O?Hara; Kristen M. Waring
2008-01-01
Three silvicultural treatment study sites are being established to examine the effects of thinning and prescribed burning on infection and spread of Phytophthora ramorum. Study sites are located in Mendocino and Santa Cruz counties, California. Stands are even-aged redwood/tanoak mixtures.
Lucy Kerhoulas; Nicholas Kerhoulas; Wade Polda; John-Pascal Berrill
2017-01-01
Reforestation following timber harvests is an important topic throughout the coast redwood (Sequoia sempervirens (D. Don) Endl.) range. Furthermore, as drought-induced mortality spreads across many of Californiaâs forests, it is important to understand how physiology and stand structure influence reforestation success. Finally, as climate...
Kyungrok Hwang; Han-sup Han; Susan E. Marshall; Deborah S. Page-Dumroese
2017-01-01
Cut-to-length (CTL) harvest systems have recently been introduced for thinning third-growth, young (<25 years old) redwood forests (Sequoia sempervirens (Lamb. ex D. Don) Endl.) in northern California. This type of harvesting can effective for thinning overstocked stands consisting of small-diameter trees. However, forestland managers and government agencies...
Daniel J. Porter; John O. Sawyer
2007-01-01
We characterized the volume, weight and top surface area of naturally fallen logs in an old-growth redwood forest, and quantified conifer recruit densities on these logs and on the surrounding forest floor. We report significantly greater conifer recruit densities on log substrates as compared to the forest floor. Log substrate availability was calculated on a per...
Directory of Open Access Journals (Sweden)
Christopher R. Keyes
2014-02-01
Full Text Available Restoration of second-growth riparian stands has become an important issue for managers of redwood (Sequoia sempervirens [D. Don] Endl. forest reserves. Identifying differences between old-growth and second-growth forest vegetation is a necessary step in evaluating restoration needs and targets. The objective of this study was to characterize and contrast vegetation structure and composition in old-growth and unmanaged second-growth riparian forests in adjacent, geomorphologically similar watersheds at Redwood National Park. In the old-growth, redwood was the dominant overstory species in terms of stem density, basal area, and importance values. Second-growth was dominated by red alder (Alnus rubra Bong., Douglas-fir (Pseudotsuga menziesii [Mirbel] Franco, and redwood. Understory species were similar in both forests, with several key differences: Oxalis oregana Nutt. and Trillium ovatum Pursh had greater importance values in the old-growth, and Vaccinium parvifolium Sm., Dryopteris spp. and sedges Carex spp. had greater importance values in the second-growth. Notable differences in structure and composition suggest that restoration practices such as thinning could expedite the acquisition of old-growth characteristics in second-growth riparian forests.
Elastic stiffnesses of an Nb-Ti/Cu-composite superconductive wire
Kim, Sudook; Ledbetter, Hassel; Ogi, Hirotsugu
2000-09-01
Elastic-stiffness coefficients were determined on a 1.4-mm-diameter wire consisting of superconducting Nb-Ti fibers in a copper matrix, with a polyvinyl-resin coating. The matrix contained 324 Nb-Ti fibers. An electromagnetic-acoustic-resonance method was used to obtain five independent elastic-stiffness coefficients assuming transverse-isotropic symmetry. From these we calculated Young moduli, bulk modulus, and principal Poisson ratios. As a check, we used a mechanical-impulse-excitation method to directly measure the Young modulus in the fiber direction. The three-phase composite wire showed a 10% anisotropy in the Young modulus.
The first principles study of elastic and thermodynamic properties of ZnSe
Khatta, Swati; Kaur, Veerpal; Tripathi, S. K.; Prakash, Satya
2018-05-01
The elastic and thermodynamic properties of ZnSe are investigated using thermo_pw package implemented in Quantum espresso code within the framework of density functional theory. The pseudopotential method within the local density approximation is used for the exchange-correlation potential. The physical parameters of ZnSe bulk modulus and shear modulus, anisotropy factor, Young's modulus, Poisson's ratio, Pugh's ratio and Frantsevich's ratio are calculated. The sound velocity and Debye temperature are obtained from elastic constant calculations. The Helmholtz free energy and internal energy of ZnSe are also calculated. The results are compared with available theoretical calculations and experimental data.
Modulus of Subgrade Reaction and Deflection
Directory of Open Access Journals (Sweden)
Austin Potts
2009-01-01
Full Text Available Differential equations govern the bending and deflection of roads under a concentrated load. Identifying critical parameters, such as the maximum deflection and maximum bending moments of a street supported by an elastic subgrade, is key to designing safe and reliable roadways. This project solves the underlying differential equation in pavement deflection and tests various parameters to highlight the importance in selecting proper foundation materials.
Crush performance of redwood for developing design procedures for impact limiters
International Nuclear Information System (INIS)
Cramer, S.M.; Hermanson, J.C.; McMurtry, W.M.
1995-01-01
Containers for the transportation of hazardous and radioactive materials incorporate redwood in impact limiters. Redwood is an excellent energy absorber, but only the most simplistic information exists on its crush properties. Tbe stress-strain interrelationship for any wood species subject to three-dimensional stresses is largely unknown for any all stress condition and wood behavior at both high strains and high strain-rates is known only in general terms. Both stress-strain and crush failure theories have been developed based only on uniaxial load tests. The anisotropy of wood adds an additional complexity to measuring wood response and developing suitable theories to describe it. A long history of wood utilization in the building industry has led to design procedures and property information related to simple uniaxial loadings that do not inflict damage to the wood. This lack of knowledge may be surprising for a material that has a long history of engineered use, but the result is difficulty in utilizing wood in more sophisticated designs such as impact limiters. This study provides a step toward filling the information gap on wood material response for high performance applications such as impact limiters
Indentation of elastically soft and plastically compressible solids
DEFF Research Database (Denmark)
Needleman, A.; Tvergaard, Viggo; Van der Giessen, E.
2015-01-01
rapidly for small deviations from plastic incompressibility and then decreases rather slowly for values of the plastic Poisson's ratio less than 0.25. For both soft elasticity and plastic compressibility, the main reason for the lower values of indentation hardness is related to the reduction......The effect of soft elasticity, i.e., a relatively small value of the ratio of Young's modulus to yield strength and plastic compressibility on the indentation of isotropically hardening elastic-viscoplastic solids is investigated. Calculations are carried out for indentation of a perfectly sticking...... rigid sharp indenter into a cylinder modeling indentation of a half space. The material is characterized by a finite strain elastic-viscoplastic constitutive relation that allows for plastic as well as elastic compressibility. Both soft elasticity and plastic compressibility significantly reduce...
Vanadium and heat treatments effect on elastic characteristics of niobium
International Nuclear Information System (INIS)
Vasil'eva, E.V.; Tret'yakov, V.I.; Prokoshkin, D.A.; Pustovalov, V.A.
1975-01-01
The effect of vanadium content and of heat treatment conditions on the elastic properties of niobium at temperatures of 20 to 800 deg C was studied. Nb-V alloys were produced by binary vacuum remelting. The Nb-V alloys have been then subjected to thermal treatment. The total degree of deformation amounts to about 95%. The specimens were tested with a view to determine their microhardness, specific electric resistance, elasticity limit and modulus of elasticity. The elastic limit of niobium rises when alloyed with vanadium. With the increase of vanadium content the elastic limit of the alloy becomes greater. Pre-crystallization annealing at 600 - 700 deg C considerably increases the elastic limit, which is explained by development of the thermally activated processes leading to a decrease of dislocation mobility and thereby to a strengthening of the alloy
Elastic constants of diamond from molecular dynamics simulations
International Nuclear Information System (INIS)
Gao Guangtu; Van Workum, Kevin; Schall, J David; Harrison, Judith A
2006-01-01
The elastic constants of diamond between 100 and 1100 K have been calculated for the first time using molecular dynamics and the second-generation, reactive empirical bond-order potential (REBO). This version of the REBO potential was used because it was redesigned to be able to model the elastic properties of diamond and graphite at 0 K while maintaining its original capabilities. The independent elastic constants of diamond, C 11 , C 12 , and C 44 , and the bulk modulus were all calculated as a function of temperature, and the results from the three different methods are in excellent agreement. By extrapolating the elastic constant data to 0 K, it is clear that the values obtained here agree with the previously calculated 0 K elastic constants. Because the second-generation REBO potential was fit to obtain better solid-state force constants for diamond and graphite, the agreement with the 0 K elastic constants is not surprising. In addition, the functional form of the second-generation REBO potential is able to qualitatively model the functional dependence of the elastic constants and bulk modulus of diamond at non-zero temperatures. In contrast, reactive potentials based on other functional forms do not reproduce the correct temperature dependence of the elastic constants. The second-generation REBO potential also correctly predicts that diamond has a negative Cauchy pressure in the temperature range examined
Membrane elastic properties and cell function.
Directory of Open Access Journals (Sweden)
Bruno Pontes
Full Text Available Recent studies indicate that the cell membrane, interacting with its attached cytoskeleton, is an important regulator of cell function, exerting and responding to forces. We investigate this relationship by looking for connections between cell membrane elastic properties, especially surface tension and bending modulus, and cell function. Those properties are measured by pulling tethers from the cell membrane with optical tweezers. Their values are determined for all major cell types of the central nervous system, as well as for macrophage. Astrocytes and glioblastoma cells, which are considerably more dynamic than neurons, have substantially larger surface tensions. Resting microglia, which continually scan their environment through motility and protrusions, have the highest elastic constants, with values similar to those for resting macrophage. For both microglia and macrophage, we find a sharp softening of bending modulus between their resting and activated forms, which is very advantageous for their acquisition of phagocytic functions upon activation. We also determine the elastic constants of pure cell membrane, with no attached cytoskeleton. For all cell types, the presence of F-actin within tethers, contrary to conventional wisdom, is confirmed. Our findings suggest the existence of a close connection between membrane elastic constants and cell function.
Fu, Y. B.; Ogden, R. W.
2001-05-01
This collection of papers by leading researchers in the field of finite, nonlinear elasticity concerns itself with the behavior of objects that deform when external forces or temperature gradients are applied. This process is extremely important in many industrial settings, such as aerospace and rubber industries. This book covers the various aspects of the subject comprehensively with careful explanations of the basic theories and individual chapters each covering a different research direction. The authors discuss the use of symbolic manipulation software as well as computer algorithm issues. The emphasis is placed firmly on covering modern, recent developments, rather than the very theoretical approach often found. The book will be an excellent reference for both beginners and specialists in engineering, applied mathematics and physics.
Pressure effect on structural, elastic, and thermodynamic properties of tetragonal B4C4
Directory of Open Access Journals (Sweden)
Baobing Zheng
2015-03-01
Full Text Available The compressibility, elastic anisotropy, and thermodynamic properties of the recently proposed tetragonal B4C4 (t-B4C4 are investigated under high temperature and high pressure by using of first-principles calculations method. The elastic constants, bulk modulus, shear modulus, Young’s modulus, Vickers hardness, Pugh’s modulus ratio, and Poisson’s ratio for t-B4C4 under various pressures are systematically explored, the obtained results indicate that t-B4C4 is a stiffer material. The elastic anisotropies of t-B4C4 are discussed in detail under pressure from 0 GPa to 100 GPa. The thermodynamic properties of t-B4C4, such as Debye temperature, heat capacity, and thermal expansion coefficient are investigated by the quasi-harmonic Debye model.
Elastic and thermal properties of silicon compounds from first-principles calculations
Energy Technology Data Exchange (ETDEWEB)
Hou, Haijun; Zhu, H.J. [Yancheng Institute of Technology (China). School of Materials Engineering; Cheng, W.H. [Yancheng Institute of Technology (China). Dept. of Light Chemical Engineering; Xie, L.H. [Sichuan Normal Univ., Chengdu (China). Inst. of Solid State Physics and School of Physics and Electronic Engineering
2016-11-01
The structural and elastic properties of V-Si (V{sub 3}Si, VSi{sub 2}, V{sub 5}Si{sub 3}, and V{sub 6}Si{sub 5}) compounds are studied by using first-principles method. The calculated equilibrium lattice parameters and formation enthalpy are in good agreement with the available experimental data and other theoretical results. The calculated results indicate that the V-Si compounds are mechanically stable. Elastic properties including bulk modulus, shear modulus, Young's modulus, and Poisson's ratio are also obtained. The elastic anisotropies of V-Si compounds are investigated via the three-dimensional (3D) figures of directional dependences of reciprocals of Young's modulus. Finally, based on the quasi-harmonic Debye model, the internal energy, Helmholtz free energy, entropy, heat capacity, thermal expansion coefficient, Grueneisen parameter, and Debye temperature of V-Si compounds have been calculated.
Propagation of Love waves in an elastic layer with void pores
Indian Academy of Sciences (India)
The paper presents a study of propagation of Love waves in a poroelastic layer resting over a poro-elastic half-space. Pores contain nothing of mechanical or energetic signiﬁcance. The study reveals that such a medium transmits two types of love waves. The ﬁrst front depends upon the modulus of rigidity of the elastic ...
Elastic properties and spectroscopic studies of Na 2 O–ZnO–B 2 O 3 ...
Indian Academy of Sciences (India)
Elastic properties, 11B MAS–NMR and IR spectroscopic studies have been employed to study the structure of Na2O–ZnO–B2O3 glasses. Sound velocities and elastic moduli such as longitudinal, Young's, bulk and shear modulus have been measured at a frequency of 10 MHz as a function of ZnO concentration.
Study on modal characteristics of perforated shell using effective Young's modulus
International Nuclear Information System (INIS)
Jhung, Myung Jo; Yu, Seon Oh
2011-01-01
Research highlights: → The effective Young's modulus of perforated shell is proposed for modal analysis. → The penetration pattern is almost negligible for effective elastic constants. → The frequency of perforated shell decreases significantly due to the hole effect. - Abstract: For the perforated cylindrical shell submerged in fluid, it is almost impossible to develop a finite element model due to the necessity of the fine meshing of the shell and the fluid at the same time. This necessitates the use of solid shell with effective material properties. Unfortunately the effective elastic constants are not found in any references even though the ASME code is suggesting those for perforated plate. Therefore in this study the effective material properties of perforated shell are suggested by performing several finite element analyses with respect to the ligament efficiencies.
Study on modal characteristics of perforated shell using effective Young's modulus
Energy Technology Data Exchange (ETDEWEB)
Jhung, Myung Jo, E-mail: mjj@kins.re.kr [Korea Institute of Nuclear Safety, 19 Guseong-dong, Yuseong-gu, Daejeon 305-338 (Korea, Republic of); Yu, Seon Oh [Korea Institute of Nuclear Safety, 19 Guseong-dong, Yuseong-gu, Daejeon 305-338 (Korea, Republic of)
2011-06-15
Research highlights: > The effective Young's modulus of perforated shell is proposed for modal analysis. > The penetration pattern is almost negligible for effective elastic constants. > The frequency of perforated shell decreases significantly due to the hole effect. - Abstract: For the perforated cylindrical shell submerged in fluid, it is almost impossible to develop a finite element model due to the necessity of the fine meshing of the shell and the fluid at the same time. This necessitates the use of solid shell with effective material properties. Unfortunately the effective elastic constants are not found in any references even though the ASME code is suggesting those for perforated plate. Therefore in this study the effective material properties of perforated shell are suggested by performing several finite element analyses with respect to the ligament efficiencies.
Atomistic simulation of the structural and elastic properties of ...
Indian Academy of Sciences (India)
experimental data and previous theoretical results, showing no phase transition ... and theoretical [2,9–11] studies have been dedicated to deter- ..... [33] introduced a simple relationship that empirically links the plastic properties of materials with their elastic moduli. The shear modulus G represents the resistance to plastic.
Elastic moduli of a Brownian colloidal glass former
Fritschi, S.; Fuchs, M.
2018-01-01
The static, dynamic and flow-dependent shear moduli of a binary mixture of Brownian hard disks are studied by an event-driven molecular dynamics simulation. Thereby, the emergence of rigidity close to the glass transition encoded in the static shear modulus G_∞ is accessed by three methods. Results from shear stress auto-correlation functions, elastic dispersion relations, and the elastic response to strain deformations upon the start-up of shear flow are compared. This enables one to sample the time-dependent shear modulus G(t) consistently over several decades in time. By that a very precise specification of the glass transition point and of G_∞ is feasible. Predictions by mode coupling theory of a finite shear modulus at the glass transition, of α-scaling in fluid states close to the transition, and of shear induced decay in yielding glass states are tested and broadly verified.
Directory of Open Access Journals (Sweden)
Eryi Hu
2016-01-01
Full Text Available The ultrasonic nondestructive method is introduced into the elastic constants measurement of metal material. The extraction principle of Poisson’s ratio, elastic modulus, and shear modulus is deduced from the ultrasonic propagating equations with two kinds of vibration model of the elastic medium named ultrasonic longitudinal wave and transverse wave, respectively. The ultrasonic propagating velocity is measured by using the digital correlation technique between the ultrasonic original signal and the echo signal from the bottom surface, and then the elastic constants of the metal material are calculated. The feasibility of the correlation algorithm is verified by a simulation procedure. Finally, in order to obtain the stability of the elastic properties of different metal materials in a variable engineering application environment, the elastic constants of two kinds of metal materials in different temperature environment are measured by the proposed ultrasonic method.
Zhao, Xin
2013-01-01
Elastic rods have been studied intensively since the 18th century. Even now the theory of elastic rods is still developing and enjoying popularity in computer graphics and physical-based simulation. Elastic rods also draw attention from architects
Elastic properties of gamma-Pu by resonant ultrasound spectroscopy
Energy Technology Data Exchange (ETDEWEB)
Migliori, Albert [Los Alamos National Laboratory; Betts, J [Los Alamos National Laboratory; Trugman, A [Los Alamos National Laboratory; Mielke, C H [Los Alamos National Laboratory; Mitchell, J N [Los Alamos National Laboratory; Ramos, M [Los Alamos National Laboratory; Stroe, I [WORXESTER, MA
2009-01-01
Despite intense experimental and theoretical work on Pu, there is still little understanding of the strange properties of this metal. We used resonant ultrasound spectroscopy method to investigate the elastic properties of pure polycrystalline Pu at high temperatures. Shear and longitudinal elastic moduli of the {gamma}-phase of Pu were determined simultaneously and the bulk modulus was computed from them. A smooth linear and large decrease of all elastic moduli with increasing temperature was observed. We calculated the Poisson ratio and found that it increases from 0.242 at 519K to 0.252 at 571K.
Elasticity and physico-chemical properties during drinking water biofilm formation.
Abe, Yumiko; Polyakov, Pavel; Skali-Lami, Salaheddine; Francius, Grégory
2011-08-01
Atomic force microscope techniques and multi-staining fluorescence microscopy were employed to study the steps in drinking water biofilm formation. During the formation of a conditioning layer, surface hydrophobic forces increased and the range of characteristic hydrophobic forces diversified with time, becoming progressively complex in macromolecular composition, which in return triggered irreversible cellular adhesion. AFM visualization of 1 to 8 week drinking water biofilms showed a spatially discontinuous and heterogeneous distribution comprising an extensive network of filamentous fungi in which biofilm aggregates were embedded. The elastic modulus of 40-day-old biofilms ranged from 200 to 9000 kPa, and the biofilm deposits with a height >0.5 μm had an elastic modulus water biofilms were composed of a soft top layer and a basal layer with significantly higher elastic modulus values falling in the range of fungal elasticity.
DEFF Research Database (Denmark)
Kanchana, V.; Vaitheeswaran, G.; Ma, Yanming
2009-01-01
agree well with the experimental values. The elastic constants of Fe2VAl and Fe2VGa are predicted. From the elastic constants the shear modulus, Young's modulus, Poisson's ratio, sound velocities, and Debye temperatures are obtained. By analyzing the ratio between the bulk and shear moduli, we conclude...
Directory of Open Access Journals (Sweden)
Boudia Keltouma
2015-12-01
Full Text Available Structural, elastic, electronic and thermodynamic properties of ternary cubic filled skutterudite compound were calculated. We have computed the elastic modulus and its pressure dependence. From the elastic parameter behavior, it is inferred that this compound is elastically stable and ductile in nature. Through the quasi-harmonic Debye model, in which phononic effects are considered, the effect of pressure P (0 to 50 GPa and temperature T (0 to 3000 °C on the lattice constant, elastic parameters, bulk modulus B, heat capacity, thermal expansion coefficient α, internal energy U, entropy S, Debye temperature θD, Helmholtz free energy A, and Gibbs free energy G are investigated.
Jong, Rudiyanto P.; Osman, Kahar; Adib, M. Azrul Hisham M.
2012-06-01
Mitral valve prolapse without proper monitoring might lead to a severe mitral valve failure which eventually leads to a sudden death. Additional information on the mitral valve leaflet condition against the backflow volume would be an added advantage to the medical practitioner for their decision on the patients' treatment. A study on two dimensional echocardiography images has been conducted and the correlations between the backflow volume of the mitral regurgitation and mitral valve leaflet Young modulus have been obtained. Echocardiogram images were analyzed on the aspect of backflow volume percentage and mitral valve leaflet dimensions on different rates of backflow volume. Young modulus values for the mitral valve leaflet were obtained by using the principle of elastic deflection and deformation on the mitral valve leaflet. The results show that the backflow volume increased with the decrease of the mitral valve leaflet Young modulus which also indicate the condition of the mitral valve leaflet approaching failure at high backflow volumes. Mitral valve leaflet Young modulus values obtained in this study agreed with the healthy mitral valve leaflet Young modulus from the literature. This is an initial overview of the trend on the prediction of the behaviour between the fluid and the structure of the blood and the mitral valve which is extendable to a larger system of prediction on the mitral valve leaflet condition based on the available echocardiogram images.
Elastic constants of a Laves phase compound: C15 NbCr2
International Nuclear Information System (INIS)
Ormeci, A.; Chu, F.; Wills, J.M.; Chen, S.P.; Albers, R.C.; Thoma, D.J.; Mitchell, T.E.
1997-01-01
The single-crystal elastic constants of C15 NbCr 2 have been computed by using a first-principles, self-consistent, full-potential total energy method. From these single-crystal elastic constants the isotropic elastic moduli are calculated using the Voigt and Reuss averages. The calculated values are in fair agreement with the experimental values. The implications of the results are discussed with regards to Poisson's ratio and the direction dependence of Young's modulus
Fast, High Resolution, and Wide Modulus Range Nanomechanical Mapping with Bimodal Tapping Mode.
Kocun, Marta; Labuda, Aleksander; Meinhold, Waiman; Revenko, Irène; Proksch, Roger
2017-10-24
Tapping mode atomic force microscopy (AFM), also known as amplitude modulated (AM) or AC mode, is a proven, reliable, and gentle imaging mode with widespread applications. Over the several decades that tapping mode has been in use, quantification of tip-sample mechanical properties such as stiffness has remained elusive. Bimodal tapping mode keeps the advantages of single-frequency tapping mode while extending the technique by driving and measuring an additional resonant mode of the cantilever. The simultaneously measured observables of this additional resonance provide the additional information necessary to extract quantitative nanomechanical information about the tip-sample mechanics. Specifically, driving the higher cantilever resonance in a frequency modulated (FM) mode allows direct measurement of the tip-sample interaction stiffness and, with appropriate modeling, the set point-independent local elastic modulus. Here we discuss the advantages of bimodal tapping, coined AM-FM imaging, for modulus mapping. Results are presented for samples over a wide modulus range, from a compliant gel (∼100 MPa) to stiff materials (∼100 GPa), with the same type of cantilever. We also show high-resolution (subnanometer) stiffness mapping of individual molecules in semicrystalline polymers and of DNA in fluid. Combined with the ability to remain quantitative even at line scan rates of nearly 40 Hz, the results demonstrate the versatility of AM-FM imaging for nanomechanical characterization in a wide range of applications.
Sensitive determination of the Young's modulus of thin films by polymeric microcantilevers
DEFF Research Database (Denmark)
Colombi, Paolo; Bergese, Paolo; Bontempi, Elza
2013-01-01
A method for the highly sensitive determination of the Young's modulus of TiO2 thin films exploiting the resonant frequency shift of a SU-8 polymer microcantilever (MC) is presented. Amorphous TiO2 films with different thickness ranging from 10 to 125 nm were grown at low temperature (90 °C......) with subnanometer thickness resolution on SU-8 MC arrays by means of atomic layer deposition. The resonant frequencies of the MCs were measured before and after coating and the elastic moduli of the films were determined by a theoretical model developed for this purpose. The Young's modulus of thicker TiO2 films...... (>75 nm) was estimated to be about 110 GPa, this value being consistent with the value of amorphous TiO2. On the other hand we observed a marked decrease of the Young's modulus for TiO2 films with a thickness below 50 nm. This behavior was found not to be related to a decrease of the film mass density...
Influence of grain size distribution on dynamic shear modulus of sands
Directory of Open Access Journals (Sweden)
Dyka Ireneusz
2017-11-01
Full Text Available The paper presents the results of laboratory tests, that verify the correlation between the grain-size characteristics of non-cohesive soils and the value of the dynamic shear modulus. The problem is a continuation of the research performed at the Institute of Soil Mechanics and Rock Mechanics in Karlsruhe, by T. Wichtmann and T. Triantafyllidis, who derived the extension of the applicability of the Hardin’s equation describing the explicite dependence between the grain size distribution of sands and the values of dynamic shear modulus. For this purpose, piezo-ceramic bender elements generating elastic waves were used to investigate the mechanical properties of the specimens with artificially generated particle distribution. The obtained results confirmed the hypothesis that grain size distribution of non-cohesive soils has a significant influence on the dynamic shear modulus, but at the same time they have shown that obtaining unambiguous results from bender element tests is a difficult task in practical applications.
First-principles calculations for elastic properties of OsB{sub 2} under pressure
Energy Technology Data Exchange (ETDEWEB)
Yang Junwei [Institute of Atomic and Molecular Physics, Sichuan University, Chengdu 610065 (China); Chen Xiangrong, E-mail: x.r.chen@tom.co [Institute of Atomic and Molecular Physics, Sichuan University, Chengdu 610065 (China); International Centre for Materials Physics, Chinese Academy of Sciences, Shenyang 110016 (China); Luo Fen [Institute of Atomic and Molecular Physics, Sichuan University, Chengdu 610065 (China); Ji Guangfu [Laboratory for Shock Wave and Detonation Physics Research, Institute of Fluid Physics, Chinese Academy of Engineering Physics, Mianyang 621900 (China)
2009-11-01
The structure, elastic properties and elastic anisotropy of orthorhombic OsB{sub 2} are investigated by density functional theory method with the ultrasoft pseudopotential scheme in the frame of the generalized gradient approximation (GGA) as well as local density approximation (LDA). The obtained structural parameters, elastic constants, elastic anisotropy and Debye temperature for OsB{sub 2} under pressure are consistent with the available experimental data and other theoretical results. It is found that the elastic constants, bulk modulus and Debye temperature of OsB{sub 2} tend to increase with increasing pressure. It is predicted that OsB{sub 2} is not a superhard material from our calculations.
First-principles calculations for elastic properties of OsB2 under pressure
International Nuclear Information System (INIS)
Yang Junwei; Chen Xiangrong; Luo Fen; Ji Guangfu
2009-01-01
The structure, elastic properties and elastic anisotropy of orthorhombic OsB 2 are investigated by density functional theory method with the ultrasoft pseudopotential scheme in the frame of the generalized gradient approximation (GGA) as well as local density approximation (LDA). The obtained structural parameters, elastic constants, elastic anisotropy and Debye temperature for OsB 2 under pressure are consistent with the available experimental data and other theoretical results. It is found that the elastic constants, bulk modulus and Debye temperature of OsB 2 tend to increase with increasing pressure. It is predicted that OsB 2 is not a superhard material from our calculations.
First-principles calculations for elastic properties of OsB 2 under pressure
Yang, Jun-Wei; Chen, Xiang-Rong; Luo, Fen; Ji, Guang-Fu
2009-11-01
The structure, elastic properties and elastic anisotropy of orthorhombic OsB 2 are investigated by density functional theory method with the ultrasoft pseudopotential scheme in the frame of the generalized gradient approximation (GGA) as well as local density approximation (LDA). The obtained structural parameters, elastic constants, elastic anisotropy and Debye temperature for OsB 2 under pressure are consistent with the available experimental data and other theoretical results. It is found that the elastic constants, bulk modulus and Debye temperature of OsB 2 tend to increase with increasing pressure. It is predicted that OsB 2 is not a superhard material from our calculations.
International Nuclear Information System (INIS)
Cikanek, E.M.; Safley, L.E.; Grant, T.A.
2003-01-01
This report reviews all potentially available Yucca Mountain Project (YMP) data in the Technical Data Management System and compiles all relevant qualified data, including data qualified by this report, on elastic properties, Poisson's ratio and Young's modulus, into a single summary Data Tracking Number (DTN) MO0304DQRIRPPR.002. Since DTN MO0304DQRIRPPR.002 was compiled from both qualified and unqualified sources, this report qualifies the DTN in accordance with AP-SIII.2Q. This report also summarizes the individual test results in MO0304DQRIRPPR.002 and provides summary values using descriptive statistics for Poisson's ratio and Young's modulus in a Reference Information Base Data Item. This report found that test conditions such as temperature, saturation, and sample size could influence test results. The largest influence, however, is the lithologic variation within the tuffs themselves. Even though the summary DTN divided the results by lithostratigrahic units within each formation, there was still substantial variation in elastic properties within individual units. This variation was attributed primarily to the presence or absence of lithophysae, fractures, alteration, pumice fragments, and other lithic clasts within the test specimens as well as changes in porosity within the units. As a secondary cause, substantial variations can also be attributed to test conditions such as the type of test (static or dynamic), size of the test specimen, degree of saturation, temperature, and strain rate conditions. This variation is characteristic of the tuffs and the testing methods, and should be considered when using the data summarized in this report
Improved measurements of elastic properties at acoustic resonant frequencies
International Nuclear Information System (INIS)
Rosinger, H.E.; Ritchie, I.G.; Shillinglaw, A.J.
1976-01-01
The choice of specimens of rectangular cross section for determination of dynamic elastic moduli by the resonant bar technique is often dictated by specimen fabrication problems. The specimen of rectangular cross section lends itself to accurate determination of elastic vibration shapes by a method in which a simple noncontacting optical transducer is used. The unequivocal indexing of the various vibration modes obtained in this way more than compensates for the added computational difficulties associated with rectangular geometry. The approximations used in the calculations of Young's modulus and the shear modulus for bars of rectangular cross section are tested experimentally and it is shown that high precision can be obtained. Determinations of changes in dynamic elastic moduli with temperature or stress are also described. (author)
Millennium-scale crossdating and inter-annual climate sensitivities of standing California redwoods.
Carroll, Allyson L; Sillett, Stephen C; Kramer, Russell D
2014-01-01
Extremely decay-resistant wood and fire-resistant bark allow California's redwoods to accumulate millennia of annual growth rings that can be useful in biological research. Whereas tree rings of Sequoiadendron giganteum (SEGI) helped formalize the study of dendrochronology and the principle of crossdating, those of Sequoia sempervirens (SESE) have proven much more difficult to decipher, greatly limiting dendroclimatic and other investigations of this species. We overcame these problems by climbing standing trees and coring trunks at multiple heights in 14 old-growth forest locations across California. Overall, we sampled 1,466 series with 483,712 annual rings from 120 trees and were able to crossdate 83% of SESE compared to 99% of SEGI rings. Standard and residual tree-ring chronologies spanning up to 1,685 years for SESE and 1,538 years for SEGI were created for each location to evaluate crossdating and to examine correlations between annual growth and climate. We used monthly values of temperature, precipitation, and drought severity as well as summer cloudiness to quantify potential drivers of inter-annual growth variation over century-long time series at each location. SESE chronologies exhibited a latitudinal gradient of climate sensitivities, contrasting cooler northern rainforests and warmer, drier southern forests. Radial growth increased with decreasing summer cloudiness in northern rainforests and a central SESE location. The strongest dendroclimatic relationship occurred in our southernmost SESE location, where radial growth correlated negatively with dry summer conditions and exhibited responses to historic fires. SEGI chronologies showed negative correlations with June temperature and positive correlations with previous October precipitation. More work is needed to understand quantitative relationships between SEGI radial growth and moisture availability, particularly snowmelt. Tree-ring chronologies developed here for both redwood species have
Soil carbon storage following road removal and timber harvesting in redwood forests
Seney, Joseph; Madej, Mary Ann
2015-01-01
Soil carbon storage plays a key role in the global carbon cycle and is important for sustaining forest productivity. Removal of unpaved forest roads has the potential for increasing carbon storage in soils on forested terrain as treated sites revegetate and soil properties improve on the previously compacted road surfaces. We compared soil organic carbon (SOC) content at several depths on treated roads to SOC in adjacent second-growth forests and old-growth redwood forests in California, determined whether SOC in the upper 50 cm of soil varies with the type of road treatment, and assessed the relative importance of site-scale and landscape-scale variables in predicting SOC accumulation in treated road prisms and second-growth redwood forests. Soils were sampled at 5, 20, and 50 cm depths on roads treated by two methods (decommissioning and full recontouring), and in adjacent second-growth and old-growth forests in north coastal California. Road treatments spanned a period of 32 years, and covered a range of geomorphic and vegetative conditions. SOC decreased with depth at all sites. Treated roads on convex sites exhibited higher SOC than on concave sites, and north aspect sites had higher SOC than south aspect sites. SOC at 5, 20, and 50 cm depths did not differ significantly between decommissioned roads (treated 18–32 years previous) and fully recontoured roads (treated 2–12 years previous). Nevertheless, stepwise multiple regression models project higher SOC developing on fully recontoured roads in the next few decades. The best predictors for SOC on treated roads and in second-growth forest incorporated aspect, vegetation type, soil depth, lithology, distance from the ocean, years since road treatment (for the road model) and years since harvest (for the forest model). The road model explained 48% of the variation in SOC in the upper 50 cm of mineral soils and the forest model, 54%
Millennium-scale crossdating and inter-annual climate sensitivities of standing California redwoods.
Directory of Open Access Journals (Sweden)
Allyson L Carroll
Full Text Available Extremely decay-resistant wood and fire-resistant bark allow California's redwoods to accumulate millennia of annual growth rings that can be useful in biological research. Whereas tree rings of Sequoiadendron giganteum (SEGI helped formalize the study of dendrochronology and the principle of crossdating, those of Sequoia sempervirens (SESE have proven much more difficult to decipher, greatly limiting dendroclimatic and other investigations of this species. We overcame these problems by climbing standing trees and coring trunks at multiple heights in 14 old-growth forest locations across California. Overall, we sampled 1,466 series with 483,712 annual rings from 120 trees and were able to crossdate 83% of SESE compared to 99% of SEGI rings. Standard and residual tree-ring chronologies spanning up to 1,685 years for SESE and 1,538 years for SEGI were created for each location to evaluate crossdating and to examine correlations between annual growth and climate. We used monthly values of temperature, precipitation, and drought severity as well as summer cloudiness to quantify potential drivers of inter-annual growth variation over century-long time series at each location. SESE chronologies exhibited a latitudinal gradient of climate sensitivities, contrasting cooler northern rainforests and warmer, drier southern forests. Radial growth increased with decreasing summer cloudiness in northern rainforests and a central SESE location. The strongest dendroclimatic relationship occurred in our southernmost SESE location, where radial growth correlated negatively with dry summer conditions and exhibited responses to historic fires. SEGI chronologies showed negative correlations with June temperature and positive correlations with previous October precipitation. More work is needed to understand quantitative relationships between SEGI radial growth and moisture availability, particularly snowmelt. Tree-ring chronologies developed here for both redwood
International Nuclear Information System (INIS)
Chung, T.; Solack, T.; Hortel, J.
1991-01-01
As part of the plant upgrade program, structural analyses and field inspections were performed on four redwood cooling towers at the DOE Portsmouth gaseous diffusion plant located in Piketon, Ohio. The cooling towers are categorized as important hazard facilities. The loadings are derived from UCRL-15910 according to the pertinent hazard category. In addition to the seismic and wind loadings, the wood cooling towers are constantly subject to adverse environmental effects such as elevated temperature, chemical attack, icing and snow load, and motor vibrations. A thorough structural evaluation for all load combinations was performed for each of the cooling towers based on the structural code requirements of the Cooling Tower Institute and National Forest Products Association. Most stress criteria are unique for the redwood material. This evaluation was performed using finite element techniques on the global structural integrity and supplemented by hand calculations on the individual connection joints. Overloaded wood structural members and joints are identified by the analysis. The rectangular tower structure sits on a concrete basin that span across 60 ft by 200 ft. A major part of the cooling towers upgrading program involved field inspections of the individual cells of each tower. The primary purpose of these inspections was to identify any existing structural damage or deficiencies such as failed members, degraded wood, and deficiencies resulting from poor construction practice. Inspection of 40 cells identified some generic deficiencies that mostly are consistent with the analytical finding. Based on the analysis, some effective but inexpensive upgrading techniques were developed and recommended to bring the cooling towers into compliance with current DOE requirements
International Nuclear Information System (INIS)
Ravindran, P.; Fast, L.; Korzhavyi, P.A.; Johansson, B.; Wills, J.; Eriksson, O.
1998-01-01
A theoretical formalism to calculate the single crystal elastic constants for orthorhombic crystals from first principle calculations is described. This is applied for TiSi 2 and we calculate the elastic constants using a full potential linear muffin-tin orbital method using the local density approximation (LDA) and generalized gradient approximation (GGA). The calculated values compare favorably with recent experimental results. An expression to calculate the bulk modulus along crystallographic axes of single crystals, using elastic constants, has been derived. From this the calculated linear bulk moduli are found to be in good agreement with the experiments. The shear modulus, Young's modulus, and Poisson's ratio for ideal polycrystalline TiSi 2 are also calculated and compared with corresponding experimental values. The directional bulk modulus and the Young's modulus for single crystal TiSi 2 are estimated from the elastic constants obtained from LDA as well as GGA calculations and are compared with the experimental results. The shear anisotropic factors and anisotropy in the linear bulk modulus are obtained from the single crystal elastic constants. From the site and angular momentum decomposed density of states combined with a charge density analysis and the elastic anisotropies, the chemical bonding nature between the constituents in TiSi 2 is analyzed. The Debye temperature is calculated from the average elastic wave velocity obtained from shear and bulk modulus as well as the integration of elastic wave velocities in different directions of the single crystal. The calculated elastic properties are found to be in good agreement with experimental values when the generalized gradient approximation is used for the exchange and correlation potential. copyright 1998 American Institute of Physics
Directory of Open Access Journals (Sweden)
JUAN LIZARAZO-MARRIAGA
2011-01-01
Full Text Available Considerando la creciente utilización de hormigón de alta resistencia como material estructural, este artículo presenta los resultados de un trabajo experimental llevado a cabo con el fin de investigar el efecto de diferentes tipos de agregados gruesos sobre el módulo estático elástico, la resistencia a la compresión, la densidad del hormigón y la velocidad del pulso. Para lograr esto, se usaron diferentes relaciones agua cementante (a/c (0.36, 0.32, y 0.28 y cuatro tipos de agregados diferentes, todos del área de influencia de Bogotá, Colombia. Como materiales cementantes se usaron cemento Portland y microsílice (SF. Los resultados experimentales fueron analizados estadísticamente, de donde se encontró que todos los ensayos se comportan siguiendo una distribución de frecuencia normal. De los datos experimentales obtenidos se concluyó que las ecuaciones propuestas en los códigos obreestiman el módulo de elasticidad del hormigón de alta resistencia, por lo que se proponen ecuaciones empíricas como alternativa.
Evaluation of elastic modulus and hardness of crop stalks cell walls by nano-indentation
Yan Wu; Siqun Wang; Dingguo Zhou; Cheng Xing; Yang Zhang; Zhiyong Cai
2010-01-01
Agricultural biomaterials such as crop stalks are natural sources of cellulosic fiber and have great potential as reinforced materials in bio-composites. In order to evaluate their potential as materials for reinforcement, the nano-mechanical properties of crop-stalk cell walls, i.e. those of cotton (Gossypium herbaceu) stalk, soybean (Glycine max) stalk, cassava (...
Computational experiences with variable modulus, elastic-plastic, and viscoelastic concrete models
International Nuclear Information System (INIS)
Anderson, C.A.
1981-01-01
Six years ago the Reactor Safety Research Division of the Nuclear Regulatory Commission (NRC) approached the Los Alamos National Laboratory to develop a comprehensive concrete structural analysis code to predict the static and dynamic behavior of Prestressed Concrete Reactor Vessels (PCRVs) that serve as the containment structure of a High-Temperature Gas-Cooled Reactor. The PCRV is a complex concrete structure that must be modeled in three dimensions and posseses other complicating features such as a steel liner for the reactor cavity and woven cables embedded vertically in the PCRV and wound circumferentially on the outside of the PCRV. The cables, or tendons, are used for prestressing the reactor vessel. In addition to developing the computational capability to predict inelastic three dimensional concrete structural behavior, the code response was verified against documented experiments on concrete structural behavior. This code development/verification effort is described
Growth and dynamic modulus of elasticity of Pinus patula × Pinus ...
African Journals Online (AJOL)
Field establishment of South Africa's most important commercial pine species, Pinus patula, is severely hampered by the pitch canker fungus, Fusarium circinatum. Importantly, hybrids between P. patula and other pine species tolerant to the pitch canker fungus, such as P. tecunumanii and P. oocarpa, have been identified ...
Directory of Open Access Journals (Sweden)
Nour M. Ajaj-ALKordy
2014-01-01
Conclusion: Within the limitations of this study, it can be concluded that the high-impact acrylic resin is a suitable denture base material for patients with clinical fracture of the acrylic denture.
Elastic Modulus of Foamcrete in Compression and Bending at Elevated Temperatures
Directory of Open Access Journals (Sweden)
Md Azree Othuman Mydin
2012-09-01
Full Text Available This paper will presents the experimental results that have been performed to examine and characterize the mechanical properties of foamcrete at elevated temperatures. Foamcrete of 650 and 1000 kg/m 3 density were cast and tested under compression and bending. The tests were done at room temperature, 100, 200, 300, 400, 500, and 600°C. The results of this study consistently demonstrated that the loss in stiffness for cement based material like foamcrete at elevated temperatures occurs predominantly after about 95°C, regardless of density. This indicates that the primary mechanism causing stiffness degradation is microcracking, which occurs as water expands and evaporates from the porous body. As expected, reducing the density of LFC reduces its strength and stiffness. However, for LFC of different densities, the normalised strength-temperature and stiffnesstemperature relationships are very similar.
The Measurement of Hardness and Elastic Modulus of non-Metallic Inclusions in Steely Welding Joints
Directory of Open Access Journals (Sweden)
Ignatova Anna
2015-08-01
Full Text Available Trunk pipelines work under a cyclic dynamical mechanical load because when oil or gas is pumped, the pressure constantly changes - pulsates. Therefore, the fatigue phenomenon is a common reason of accidents. The fatigue phenomenon more often happens in the zone of non-metallic inclusions concentration. To know how the characteristics of nonmetallic inclusions influence the probability of an accident the most modern research methods should be used. It is determined with the help of the modern research methods that the accident rate of welded joints of pipelines is mostly influenced by their morphological type, composition and size of nonmetallic inclusions, this effect is more important than the common level of pollution by non-metallic inclusions. The article presents the results of the investigations of welded joints, obtained after the use of different common welding materials. We used the methods, described in the state standards: scanning electronic microscopy, spectral microprobe analysis and nano-indentation. We found out that non-metallic inclusions act like stress concentrators because they shrink, forming a blank space between metal and nonmetallic inclusions; it strengthens the differential properties on this boundary. Nonmetallic inclusion is not fixed, it can move. The data that we have received mean that during welded joints’ contamination (with non-metallic inclusions monitoring process, more attention should be paid to the content of definite inclusions, but not to total contamination.
Crack arrest within teeth at the dentinoenamel junction caused by elastic modulus mismatch
Bechtle, Sabine
2010-01-01
Enamel and dentin compose the crowns of human teeth. They are joined at the dentinoenamel junction (DEJ) which is a very strong and well-bonded interface unlikely to fail within healthy teeth despite the formation of multiple cracks within enamel during a lifetime of exposure to masticatory forces. These cracks commonly are arrested when reaching the DEJ. The phenomenon of crack arrest at the DEJ is described in many publications but there is little consensus on the underlying cause and mecha...
Highly porous, low elastic modulus 316L stainless steel scaffold prepared by selective laser melting
Czech Academy of Sciences Publication Activity Database
Čapek, Jaroslav; Machová, M.; Fousová, M.; Kubásek, J.; Vojtěch, D.; Fojt, J.; Jablonská, E.; Lipov, J.; Ruml, T.
2016-01-01
Roč. 69, Dec (2016), 631–639 ISSN 0928-4931 R&D Projects: GA ČR GBP108/12/G043 Institutional support: RVO:68378271 Keywords : selective laser melting * 316L stainless steel * porous implants * scaffolds Subject RIV: BM - Solid Matter Physics ; Magnetism
Directory of Open Access Journals (Sweden)
Flávio de Souza-Barbosa
2015-01-01
Full Text Available Este trabajo propone una metodolo gía para evaluar el módulo elá stico de los hormigones de agre gados livianos. Para ello una fó rmula analítica se logra mediante el ajuste de la c urva de los resultados experime ntales de 135 muestras de hormigón hechas de 45 mezclas diferen tes. La validación de la metodología propuesta se lle va a cabo mediante la aplicac ión de la fórmula analítica obtenida a otro conjunto de 90 mues tras de hormigón hecha de 30 mezclas diferentes. Las c omparaciones con otros métodos u tilizados para predecir el módul o de elasticidad de hormigones de agregados livianos muestran que los resultados sean justos y sugieren que la metodología propuesta podría aplicarse en situaciones prácticas.
2009-10-01
A laboratory testing program was performed to evaluate the physical and mechanical properties of typical Class II, IV, V, and VI concrete mixtures made with a Miami Oolite limestone, a Georgia granite, and a lightweight aggregate Stalite, including c...
DEFF Research Database (Denmark)
Sørensen, Morten Kanne; Fabricius, Ida Lykke
2017-01-01
The elastic bulk modulus of a sandstone is affected by the fluid saturation as compression induces a pressure in the fluid thus increasing the bulk modulus of the sandstone as a whole. Assuming a uniform induced pressure and no interaction between the saturating fluid and the solid rock the fluid...... contribution to the elastic bulk modulus is quantified by Gassmann's equations. Experimental measurements of the fluid contribution to the elastic moduli are, however often much larger than predicted within the assumptions of Gassmann. Clay-rich low-mobility sandstones are especially prone to having elastic...... moduli highly sensitive to the fluid saturation. The presence of clay in a sandstone can affect two of the underlying assumptions to Gassmann's equations: decreased fluid mobility can cause pressure gradients and fluid-clay interactions are common. The elastic and petrophysical properties of clay...
International Nuclear Information System (INIS)
Perepechko, I.I.; Mar'yasin, B.Ya.
1978-01-01
The effect of γ radiation on visco-elastic properties of polymethylmethacrylate (PMMA) and poly-4-methylpentene-1 (P4MPI) has been investigated by the method of the forced resonance oscillations of a cantilevered specimen. It has been shown, that the variation of the dynamic elasticity modulus of amorphous polymer when the irradiation dose increases, considerable depends on the polymer physical state during the measurement. The irradiated polymer is a binary mixture of radiolysis low-molecular products and polymer itself. The value of elasticity modulus in such a mixture is defined by the modules of different components. More complex than in PMMA in the effect of γ-radiation upon the P4MPI visco-elastic behaviour. During the P4MPI irradiation, the rebuilding of polymer supermolecular structure takes place, which results in the variation of the dynamic elasticity modulus values and in the intensity of peaks of mechanical losses
Elastic anisotropy and low-temperature thermal expansion in the shape memory alloy Cu-Al-Zn.
Kuruvilla, Santhosh Potharay; Menon, C S
2008-04-01
Cu-based shape memory alloys are known for their technologically important pseudo-elastic and shapememory properties, which are intimately associated with the martensitic transformation. A combination of deformation theory and finite-strain elasticity theory has been employed to arrive at the expressions for higher order elastic constants of Cu-Al-Zn based on Keating's approach. The second- and third-order elastic constants are in good agreement with the measurements. The aggregate elastic properties like bulk modulus, pressure derivatives, mode Grüneisen parameters of the elastic waves, low temperature limit of thermal expansion, and the Anderson-Grüneisen parameter are also presented.
On Young's modulus of multi-walled carbon nanotubes
Indian Academy of Sciences (India)
WINTEC
load transfer in nanocomposites. In the present work, CNT/Al ... calculations. The theoretical modulus of the graphene sheet is supposed to be 1060 GPa (Harris 2004). The reason why multi-walled nanotubes have a modulus > 1060 GPa (that of graphene sheet) is currently not understood. However, in the present paper, ...
Dimitrakopoulos, P; Kuriakose, S
2015-04-14
Determination of the elastic properties of the membrane of artificial capsules is essential for the better design of the various devices that are utilized in their engineering and biomedical applications. However this task is complicated owing to the combined effects of the shear and area-dilatation moduli on the capsule deformation. Based on computational investigation, we propose a new methodology to determine a membrane's shear modulus, independent of its area-dilatation modulus, by flowing strain-hardening capsules in a converging micro-capillary of comparable size under Stokes flow conditions, and comparing the experimental measurements of the capsule elongation overshooting with computational data. The capsule prestress, if any, can also be determined with the same methodology. The elongation overshooting is practically independent of the viscosity ratio for low and moderate viscosity ratios, and thus a wide range of capsule fluids can be employed. Our proposed experimental device can be readily produced via glass fabrication while owing to the continuous flow in the micro-capillary, the characterization of a large number of artificial capsules is possible.
Young’s modulus of multi-layer microcantilevers
Directory of Open Access Journals (Sweden)
Zhikang Deng
2017-12-01
Full Text Available A theoretical model for calculating the Young’s modulus of multi-layer microcantilevers with a coating is proposed, and validated by a three-dimensional (3D finite element (FE model using ANSYS parametric design language (APDL and atomic force microscopy (AFM characterization. Compared with typical theoretical models (Rayleigh-Ritz model, Euler-Bernoulli (E-B beam model and spring mass model, the proposed theoretical model can obtain Young’s modulus of multi-layer microcantilevers more precisely. Also, the influences of coating’s geometric dimensions on Young’s modulus and resonant frequency of microcantilevers are discussed. The thickness of coating has a great influence on Young’s modulus and resonant frequency of multi-layer microcantilevers, and the coating should be considered to calculate Young’s modulus more precisely, especially when fairly thicker coating is employed.
Zhao, Xin
2013-05-01
Elastic rods have been studied intensively since the 18th century. Even now the theory of elastic rods is still developing and enjoying popularity in computer graphics and physical-based simulation. Elastic rods also draw attention from architects. Architectural structures, NODUS, were constructed by elastic rods as a new method of form-finding. We study discrete models of elastic rods and NODUS structures. We also develop computational tools to find the equilibria of elastic rods and the shape of NODUS. Applications of elastic rods in forming torus knot and closing Bishop frame are included in this thesis.
Pietroni, P; Lebeau, M; Majni, G; Rinaldi, D
2005-01-01
For a reliable mechanical assembly of scintillating crystals for the application to radiographic systems such as Positron Emission Tomographer (PET) and high-energy physics calorimeters (e.g. in CMS at CERN LHC), the evaluation of the monocrystal elastic constant (Young's modulus) is needed. Its knowledge is also essential in the photoelastic analysis for the determination of residual stresses. In this work non-destructive techniques based on elastic wave propagation are tested. They differ in the mechanical excitation device: instrumented hammer, traditional ultrasonic probes and laser- generated ultrasound. We have analysed three non-oriented cerium fluoride crystal samples produced for scintillation applications. Finally, we have validated the experimental results comparing them with the elastic constant calculated by using the stiffness matrix.
Development of non-destructive Young's modulus measurement techniques in non-oriented CeF3 crystals
International Nuclear Information System (INIS)
Pietroni, P.; Paone, N.; Lebeau, M.; Majni, G.; Rinaldi, D.
2005-01-01
For a reliable mechanical assembly of scintillating crystals for the application to radiographic systems such as Positron Emission Tomographer (PET) and high-energy physics calorimeters (e.g. in CMS at CERN LHC), the evaluation of the monocrystal elastic constant (Young's modulus) is needed. Its knowledge is also essential in the photoelastic analysis for the determination of residual stresses. In this work non-destructive techniques based on elastic wave propagation are tested. They differ in the mechanical excitation device: instrumented hammer, traditional ultrasonic probes and laser-generated ultrasound. We have analysed three non-oriented cerium fluoride crystal samples produced for scintillation applications. Finally, we have validated the experimental results comparing them with the elastic constant calculated by using the stiffness matrix
First-principles study of structural and elastic properties of monoclinic and orthorhombic BiMnO3
International Nuclear Information System (INIS)
Mei Zhigang; Shang Shunli; Wang Yi; Liu Zikui
2010-01-01
The structural and elastic properties of BiMnO 3 with monoclinic (C 2/c) and orthorhombic (Pnma) ferromagnetic (FM) structures have been studied by first-principles calculations within LDA + U and GGA + U approaches. The equilibrium volumes and bulk moduli of BiMnO 3 phases are evaluated by equation of state (EOS) fittings, and the bulk properties predicted by LDA + U calculations are in better agreement with experiment. The orthorhombic phase is found to be more stable than the monoclinic phase at ambient pressure. A monoclinic to monoclinic phase transition is predicted to occur at a pressure of about 10 GPa, which is ascribed to magnetism versus volume instability of monoclinic BiMnO 3 . The single-crystal elastic stiffness constants c ij s of the monoclinic and orthorhombic phases are investigated using the stress-strain method. The c 46 of the monoclinic phase is predicted to be negative. In addition, the polycrystalline elastic properties including bulk modulus, shear modulus, Young's modulus, bulk modulus-shear modulus ratio, Poisson's ratio, and elastic anisotropy ratio are determined based on the calculated elastic constants. The presently predicted phase transition and elastic properties open new directions for investigation of the phase transitions in BiMnO 3 , and provide helpful guidance for the future elastic constant measurements.
California Natural Resource Agency — California Spatial Information System (CaSIL) is a project designed to improve access to geo-spatial and geo-spatial related data information throughout the state of...
On elastic moduli and elastic anisotropy in polycrystalline martensitic NiTi
International Nuclear Information System (INIS)
Qiu, S.; Clausen, B.; Padula, S.A.; Noebe, R.D.; Vaidyanathan, R.
2011-01-01
A combined experimental and computational effort was undertaken to provide insight into the elastic response of B19' martensitic NiTi variants as they exist in bulk, polycrystalline aggregate form during monotonic tensile and compressive loading. The experimental effort centered on using in situ neutron diffraction during loading to measure elastic moduli in several directions along with an average Young's modulus and a Poisson's ratio. The measurements were compared with predictions from a 30,000 variant, self-consistent polycrystalline deformation model that accounted for the elastic intergranular constraint, and also with predictions of single crystal behavior from previously published ab initio studies. Variant conversion and detwinning processes that influenced the intergranular constraint occurred even at stresses where the macroscopic stress-strain response appeared linear. Direct evidence of these processes was revealed in changes in texture, which were captured in inverse pole figures constructed from the neutron diffraction measurements.
On elastic moduli and elastic anisotropy in polycrystalline martensitic NiTi
Energy Technology Data Exchange (ETDEWEB)
Qiu, S. [Advanced Materials Processing and Analysis Center (AMPAC), Mechanical, Materials and Aerospace Engineering Department, University of Central Florida, Orlando, FL 32816 (United States); Clausen, B. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Padula, S.A.; Noebe, R.D. [NASA Glenn Research Center, Cleveland, OH 44135 (United States); Vaidyanathan, R., E-mail: raj@mail.ucf.edu [Advanced Materials Processing and Analysis Center (AMPAC), Mechanical, Materials and Aerospace Engineering Department, University of Central Florida, Orlando, FL 32816 (United States)
2011-08-15
A combined experimental and computational effort was undertaken to provide insight into the elastic response of B19' martensitic NiTi variants as they exist in bulk, polycrystalline aggregate form during monotonic tensile and compressive loading. The experimental effort centered on using in situ neutron diffraction during loading to measure elastic moduli in several directions along with an average Young's modulus and a Poisson's ratio. The measurements were compared with predictions from a 30,000 variant, self-consistent polycrystalline deformation model that accounted for the elastic intergranular constraint, and also with predictions of single crystal behavior from previously published ab initio studies. Variant conversion and detwinning processes that influenced the intergranular constraint occurred even at stresses where the macroscopic stress-strain response appeared linear. Direct evidence of these processes was revealed in changes in texture, which were captured in inverse pole figures constructed from the neutron diffraction measurements.
FP-LAPW study of the elastic properties of Al2X (X=Sc,Y,La,Lu)
International Nuclear Information System (INIS)
Rajagopalan, M.; Praveen Kumar, S.; Anuthama, R.
2010-01-01
From the first principles total energy calculations based on full-potential linear augmented plane wave method (FP-LAPW), the elastic properties of Al 2 X (X=Sc,Y,La,Lu) are reported here. Theoretical values of Young's modulus, shear modulus, Poisson's ratio and Debye temperature are estimated from the computed elastic constants. From the analysis of the ratio of shear to bulk modulus, it is found that these intermetallic compounds are brittle in nature. The calculated results are compared with other reported values.
Substrate-dependent cell elasticity measured by optical tweezers indentation
Yousafzai, Muhammad S.; Ndoye, Fatou; Coceano, Giovanna; Niemela, Joseph; Bonin, Serena; Scoles, Giacinto; Cojoc, Dan
2016-01-01
In the last decade, cell elasticity has been widely investigated as a potential label free indicator for cellular alteration in different diseases, cancer included. Cell elasticity can be locally measured by pulling membrane tethers, stretching or indenting the cell using optical tweezers. In this paper, we propose a simple approach to perform cell indentation at pN forces by axially moving the cell against a trapped microbead. The elastic modulus is calculated using the Hertz-model. Besides the axial component, the setup also allows us to examine the lateral cell-bead interaction. This technique has been applied to measure the local elasticity of HBL-100 cells, an immortalized human cell line, originally derived from the milk of a woman with no evidence of breast cancer lesions. In addition, we have studied the influence of substrate stiffness on cell elasticity by performing experiments on cells cultured on two substrates, bare and collagen-coated, having different stiffness. The mean value of the cell elastic modulus measured during indentation was 26±9 Pa for the bare substrate, while for the collagen-coated substrate it diminished to 19±7 Pa. The same trend was obtained for the elastic modulus measured during the retraction of the cell: 23±10 Pa and 13±7 Pa, respectively. These results show the cells adapt their stiffness to that of the substrate and demonstrate the potential of this setup for low-force probing of modifications to cell mechanics induced by the surrounding environment (e.g. extracellular matrix or other cells).
Inverse problemfor an inhomogeneous elastic beam at a combined strength
Directory of Open Access Journals (Sweden)
Andreev Vladimir Igorevich
2014-01-01
Full Text Available In the article the authors describe a method of optimizing the stress state of an elastic beam, subject to the simultaneous action of the central concentrated force and bending moment. The optimization method is based on solving the inverse problem of the strength of materials, consisting in defining the law of changing in elasticity modulus with beam cross-section altitude. With this changing the stress state will be preset. Most problems of the elasticity theory of inhomogeneous bodies are solved in direct formulation, the essence of which is to determine the stress-strain state of a body at the known dependences of the material elastic characteristics from the coordinates. There are also some solutions of the inverse problems of the elasticity theory, in which the dependences of the mechanical characteristics from the coordinates, at which the stress state of a body is preset, are determined. In the paper the authors solve the problem of finding a dependence modulus of elasticity, where the stresses will be constant over the beam’s cross section. We will solve the problem of combined strength (in the case of the central stretching and bending. We will use an iterative method. As the initial solution, we take the solution for a homogeneous material. As the first approximation, we consider the stress state of a beam, when the modulus of elasticity varies linearly. According to the results, it can be stated that three approximations are sufficient in the considered problem. The obtained results allow us to use them in assessing the strength of a beam and its optimization.
Theoretical studies of the pressure-induced phase transition and elastic properties of BeS
Energy Technology Data Exchange (ETDEWEB)
Ji, Xu [College of Polymer Science and Engineering, Sichuan University, Chengdu 610065 (China); College of Chemical Engineering, Sichuan University, Chengdu 610065 (China); Yu, Yang, E-mail: yuyang@scu.edu.cn [Department of Logistics Management, Sichuan University, Chengdu 610065 (China); Ji, Junyi [College of Chemical Engineering, Sichuan University, Chengdu 610065 (China); Long, Jianping [College of Materials and Chemistry and Chemical Engineering, Chengdu University of Technology, Chengdu 610059 (China); Chen, Jianjun; Liu, Daijun [College of Chemical Engineering, Sichuan University, Chengdu 610065 (China)
2015-02-25
Highlights: • Transition pressure from B3 to B8 of BeS is 58.86 GPa. • Elastic properties of BeS under pressure are predicted for the first time. • Elastic moduli of BeS increase monotonically with increasing pressure. • Elastic anisotropy of BeS has been investigated. - Abstract: First-principles calculations were performed to investigate the structural, electronic and elastic properties of BeS in both B3 and B8 structures. The structural phase transition from B3 to B8 occurs at 58.86 GPa with a volume decrease of 10.74%. The results of the electronic band structure show that the energy gap is indirect for B3 and B8 phases. The pressure dependence of the direct and indirect band gaps for BeS has been investigated. Especially, the elastic constants of B8 BeS under high pressure have been studied for the first time. The mechanical stability of the two phases has been discussed based on the pressure dependence of the elastic constants. In addition, the pressure dependence of bulk modulus, shear modulus, Young’s modulus, elastic wave velocities and brittle–ductile behavior of BeS are all successfully obtained. Finally, the elastic anisotropy has been investigated by using two different methods.
International Nuclear Information System (INIS)
Lacey, G.; Thenoux, G.; Rodriguez-Roa, F.
2008-01-01
In accordance with the present development of empirical-mechanistic tools, this paper presents an alternative to traditional analysis methods for flexible pavements using a three-dimensional finite element formulation based on a liner-elastic perfectly-plastic Drucker-Pager model for granular soil layers and a linear-elastic stress-strain law for the asphalt layer. From the sensitivity analysis performed, it was found that variations of +-4 degree in the internal friction angle of granular soil layers did not significantly affect the analyzed pavement response. On the other hand, a null dilation angle is conservatively proposed for design purposes. The use of a Light Falling Weight Deflectometer is also proposed as an effective and practical tool for on-site elastic modulus determination of granular soil layers. However, the stiffness value obtained from the tested layer should be corrected when the measured peak deflection and the peak force do not occur at the same time. In addition, some practical observations are given to achieve successful field measurements. The importance of using a 3D FE analysis to predict the maximum tensile strain at the bottom of the asphalt layer (related to pavement fatigue) and the maximum vertical comprehensive strain transmitted to the top of the granular soil layers (related to rutting) is also shown. (author)
International Nuclear Information System (INIS)
Bender, P.; Tschöpe, A.; Birringer, R.
2013-01-01
Ni nanorods are dispersed into gelatine gels and used as nanoprobes to estimate the shear modulus of the surrounding gel matrix by magnetization measurements. The nanorods are synthesized via pulsed electrodeposition of Ni into porous alumina, released from the templates by dissolution of the oxide layer and after several processing steps dispersed into gelatine gels with an isotropic orientation-distribution. Magnetization measurements of the resulting gels show a significant influence of the gelatine concentration on their magnetic behavior. In particular, with decreasing gelatine concentration the measured coercivity is reduced indicating a mechanical rotation of the nanorods in the field direction. A theoretical model which relates the measured coercivity to the shear modulus of the surrounding gel matrix is introduced and applied to investigate the ageing process of gelatine gels with different gelatine concentrations at room temperature. - Highlights: • AAO-template synthesis of uniaxial ferromagnetic single domain Ni nanorods. • Embedding nanorods as magnetic probes in soft elastic gelatine hydrogels. • Coercivity of isotropic samples increases with gelation time and gelatine concentration. • Quantitative relationship between coercivity and matrix shear modulus is obtained from an extended Stoner–Wohlfarth-model. • Semi-quantitative method for magnetic rheometry of soft elastic materials
Energy Technology Data Exchange (ETDEWEB)
Bender, P., E-mail: nano@p-bender.de; Tschöpe, A., E-mail: antsch@mx.uni-saarland.de; Birringer, R., E-mail: r.birringer@nano.uni-saarland.de
2013-11-15
Ni nanorods are dispersed into gelatine gels and used as nanoprobes to estimate the shear modulus of the surrounding gel matrix by magnetization measurements. The nanorods are synthesized via pulsed electrodeposition of Ni into porous alumina, released from the templates by dissolution of the oxide layer and after several processing steps dispersed into gelatine gels with an isotropic orientation-distribution. Magnetization measurements of the resulting gels show a significant influence of the gelatine concentration on their magnetic behavior. In particular, with decreasing gelatine concentration the measured coercivity is reduced indicating a mechanical rotation of the nanorods in the field direction. A theoretical model which relates the measured coercivity to the shear modulus of the surrounding gel matrix is introduced and applied to investigate the ageing process of gelatine gels with different gelatine concentrations at room temperature. - Highlights: • AAO-template synthesis of uniaxial ferromagnetic single domain Ni nanorods. • Embedding nanorods as magnetic probes in soft elastic gelatine hydrogels. • Coercivity of isotropic samples increases with gelation time and gelatine concentration. • Quantitative relationship between coercivity and matrix shear modulus is obtained from an extended Stoner–Wohlfarth-model. • Semi-quantitative method for magnetic rheometry of soft elastic materials.
CSIR Research Space (South Africa)
De Beer, Morris
2008-07-01
Full Text Available - wave and ρ the material density. The elastic moduli P-wave modulus, M, is defined so that M = K + 4µ / 3 and M can then be determined by Equation 11, with a known speed Vp P MV 2 ρ = (11) It should however also... gas (such as air within compacted road materials), the adiabatic bulk modulus KS is approximately given by pKS κ= (4) Where: κ is the adiabatic index, (sometimes calledγ ); p is the pressure. In a fluid (such as moisture...
Li, Pan; Zhang, Jianxin; Ma, Shiyu; Jin, Huixin; Zhang, Youjian; Zhang, Wenyang
2018-06-01
The structural, elastic, electronic properties and Debye temperature of Ni3Ta under different pressures are investigated using the first-principles method based on density functional theory. Our calculated equilibrium lattice parameters at 0 GPa well agree with the experimental and previous theoretical results. The calculated negative formation enthalpies and elastic constants both indicate that Ni3Ta is stable under different pressures. The bulk modulus B, shear modulus G, Young's modulus E and Poisson's ratio ν are calculated by the Voigt-Reuss-Hill method. The bigger ratio of B/G indicates Ni3Ta is ductile and the pressure can improve the ductility of Ni3Ta. In addition, the results of density of states and the charge density difference show that the stability of Ni3Ta is improved by the increasing pressure. The Debye temperature ΘD calculated from elastic modulus increases along with the pressure.
The elastic constants and anisotropy of superconducting MgCNi3 and CdCNi3 under different pressure
Feng, Huifang
2013-11-23
The second-order elastic constants (SOECs) and third-order elastic constants (TOECs) of MgCNi3 and CdCNi3 are presented by using first-principles methods combined with homogeneous deformation theory. The Voigt-Reuss-Hill (VRH) approximation are used to calculate the bulk modulus B, shear modulus G, averaged Young\\'s modulus E and Poisson\\'s ratio ν for polycrystals and these effective modulus are consistent with the experiments. The SOECs under different pressure of MgCNi3 and CdCNi3 are also obtained based on the TOECs. Furthermore, the Zener anisotropy factor, Chung-Buessem anisotropy index, and the universal anisotropy index are used to describe the anisotropy of MgCNi3 and CdCNi3. The anisotropy of Young\\'s modulus of single-crystal under different pressure is also presented. © 2013 Springer Science+Business Media New York.
Elastic softness of hybrid lead halide perovskites
Ferreira, A. C.
2018-01-26
Much recent attention has been devoted towards unravelling the microscopic optoelectronic properties of hybrid organic-inorganic perovskites (HOP). Here we investigate by coherent inelastic neutron scattering spectroscopy and Brillouin light scattering, low frequency acoustic phonons in four different hybrid perovskite single crystals: MAPbBr3, FAPbBr3, MAPbI3 and α-FAPbI3 (MA: methylammonium, FA: formamidinium). We report a complete set of elastic constants caracterized by a very soft shear modulus C44. Further, a tendency towards an incipient ferroelastic transition is observed in FAPbBr3. We observe a systematic lower sound group velocity in the technologically important iodide-based compounds compared to the bromide-based ones. The findings suggest that low thermal conductivity and hot phonon bottleneck phenomena are expected to be enhanced by low elastic stiffness, particularly in the case of the ultrasoft α-FAPbI3.
Directory of Open Access Journals (Sweden)
Luiz Claudio Pardini
2002-10-01
Full Text Available Carbon fibres and glass fibres are reinforcements for advanced composites and the fiber strength is the most influential factor on the strength of the composites. They are essentially brittle and fail with very little reduction in cross section. Composites made with these fibres are characterized by a high strength/density ratio and their properties are intrisically related to their microstructure, i.e., amount and orientation of the fibres, surface treatment, among other factors. Processing parameters have an important role in the fibre mechanical behaviour (strength and modulus. Cracks, voids and impurities in the case of glass fibres and fibrillar misalignments in the case of carbon fibres are created during processing. Such inhomogeneities give rise to an appreciable scatter in properties. The most used statistical tool that deals with this characteristic variability in properties is the Weibull distribution. The present work investigates the influence of the testing gage length on the strength, Young's modulus and Weibull modulus of carbon fibres and glass fibres. The Young's modulus is calculated by two methods: (i ASTM D 3379M, and (ii interaction between testing equipment/specimen The first method resulted in a Young modulus of 183 GPa for carbon fibre, and 76 GPa for glass fibre. The second method gave a Young modulus of 250 GPa for carbon fibre and 50 GPa for glass fibre. These differences revelead differences on how the interaction specimen/testing machine can interfere in the Young modulus calculations. Weibull modulus can be a tool to evaluate the fibre's homogeneity in terms of properties and it is a good quality control parameter during processing. In the range of specimen gage length tested the Weibull modulus for carbon fibre is ~ 3.30 and for glass fibres is ~ 5.65, which indicates that for the batch of fibres tested, the glass fibre is more uniform in properties.
International Nuclear Information System (INIS)
Doyley, Marvin M; Srinivasan, Seshadri; Dimidenko, Eugene; Soni, Nirmal; Ophir, Jonathan
2006-01-01
Model-based elastography is fraught with problems owing to the ill-posed nature of the inverse elasticity problem. To overcome this limitation, we have recently developed a novel inversion scheme that incorporates a priori information concerning the mechanical properties of the underlying tissue structures, and the variance incurred during displacement estimation in the modulus image reconstruction process. The information was procured by employing standard strain imaging methodology, and introduced in the reconstruction process through the generalized Tikhonov approach. In this paper, we report the results of experiments conducted on gelatin phantoms to evaluate the performance of modulus elastograms computed with the generalized Tikhonov (GTK) estimation criterion relative to those computed by employing the un-weighted least-squares estimation criterion, the weighted least-squares estimation criterion and the standard Tikhonov method (i.e., the generalized Tikhonov method with no modulus prior). The results indicate that modulus elastograms computed with the generalized Tikhonov approach had superior elastographic contrast discrimination and contrast recovery. In addition, image reconstruction was more resilient to structural decorrelation noise when additional constraints were imposed on the reconstruction process through the GTK method
International Nuclear Information System (INIS)
Kardashev, B.K.; Nikanorov, S.P.; Kravchenko, V.S.; Malinov, V.I.; Punin, V.T.
2007-01-01
The influence of vibrational deformation amplitude on the dynamic elasticity modulus and internal friction of high-pressure polyethylene samples with different histories is studied. Acoustic measurements are made by a resonance method using the longitudinal vibrations of a composite piezoelectric vibrator at a frequency of ∼ 100 kHz. It is found that the microplasticity remains almost unaffected upon irradiation and aging, while the elasticity modulus and breaking elongation per unit length considerably depend on the history and are clearly correlated with each other. The observed effects are explained by the fact that atom-atom interaction and defects inside polymer macromolecules substantially influence the elastic modulus and breaking strength, while the inelastic microplastic strain is most likely associated with molecule-molecule interaction, which is insignificantly affected by irradiation [ru
Ultrasound Shear Wave Simulation of Breast Tumor Using Nonlinear Tissue Elasticity
Directory of Open Access Journals (Sweden)
Dae Woo Park
2016-01-01
Full Text Available Shear wave elasticity imaging (SWEI can assess the elasticity of tissues, but the shear modulus estimated in SWEI is often less sensitive to a subtle change of the stiffness that produces only small mechanical contrast to the background tissues. Because most soft tissues exhibit mechanical nonlinearity that differs in tissue types, mechanical contrast can be enhanced if the tissues are compressed. In this study, a finite element- (FE- based simulation was performed for a breast tissue model, which consists of a circular (D: 10 mm, hard tumor and surrounding tissue (soft. The SWEI was performed with 0% to 30% compression of the breast tissue model. The shear modulus of the tumor exhibited noticeably high nonlinearity compared to soft background tissue above 10% overall applied compression. As a result, the elastic modulus contrast of the tumor to the surrounding tissue was increased from 0.46 at 0% compression to 1.45 at 30% compression.
Ultrasound Shear Wave Simulation of Breast Tumor Using Nonlinear Tissue Elasticity.
Park, Dae Woo
2015-01-01
Shear wave elasticity imaging (SWEI) can assess the elasticity of tissues, but the shear modulus estimated in SWEI is often less sensitive to a subtle change of the stiffness that produces only small mechanical contrast to the background tissues. Because most soft tissues exhibit mechanical nonlinearity that differs in tissue types, mechanical contrast can be enhanced if the tissues are compressed. In this study, a finite element- (FE-) based simulation was performed for a breast tissue model, which consists of a circular (D: 10 mm, hard) tumor and surrounding tissue (soft). The SWEI was performed with 0% to 30% compression of the breast tissue model. The shear modulus of the tumor exhibited noticeably high nonlinearity compared to soft background tissue above 10% overall applied compression. As a result, the elastic modulus contrast of the tumor to the surrounding tissue was increased from 0.46 at 0% compression to 1.45 at 30% compression.
Standardizing lightweight deflectometer modulus measurements for compaction quality assurance
2017-09-01
To evaluate the compaction of unbound geomaterials under unsaturated conditions and replace the conventional methods with a practical modulus-based specification using LWD, this study examined three different LWDs, the Zorn ZFG 3000 LWD, Dynatest 303...
Estimate of K-functionals and modulus of smoothness constructed ...
Indian Academy of Sciences (India)
2016-08-26
functional and a modulus of smoothness for the Dunkl transform on Rd. Author Affiliations. M El Hamma1 R Daher1. Department of Mathematics, Faculty of Sciences Aïn Chock, University of Hassan II, Casablanca, Morocco. Dates.
Frequency-dependent complex modulus of the uterus: preliminary results
Energy Technology Data Exchange (ETDEWEB)
Kiss, Miklos Z [Department of Medical Physics, University of Wisconsin, Madison, WI 53706 (United States); Hobson, Maritza A [Department of Medical Physics, University of Wisconsin, Madison, WI 53706 (United States); Varghese, Tomy [Department of Medical Physics, University of Wisconsin, Madison, WI 53706 (United States); Harter, Josephine [Department of Surgical Pathology, University of Wisconsin, Madison, WI 53706 (United States); Kliewer, Mark A [Department of Radiology, University of Wisconsin, Madison, WI 53706 (United States); Hartenbach, Ellen M [Department of Obstetrics and Gynecology, University of Wisconsin, Madison, WI 53706 (United States); Zagzebski, James A [Department of Medical Physics, University of Wisconsin, Madison, WI 53706 (United States)
2006-08-07
The frequency-dependent complex moduli of human uterine tissue have been characterized. Quantification of the modulus is required for developing uterine ultrasound elastography as a viable imaging modality for diagnosing and monitoring causes for abnormal uterine bleeding and enlargement, as well assessing the integrity of uterine and cervical tissue. The complex modulus was measured in samples from hysterectomies of 24 patients ranging in age from 31 to 79 years. Measurements were done under small compressions of either 1 or 2%, at low pre-compression values (either 1 or 2%), and over a frequency range of 0.1-100 Hz. Modulus values of cervical tissue monotonically increased from approximately 30-90 kPa over the frequency range. Normal uterine tissue possessed modulus values over the same range, while leiomyomas, or uterine fibroids, exhibited values ranging from approximately 60-220 kPa.
Frequency-dependent complex modulus of the uterus: preliminary results
International Nuclear Information System (INIS)
Kiss, Miklos Z; Hobson, Maritza A; Varghese, Tomy; Harter, Josephine; Kliewer, Mark A; Hartenbach, Ellen M; Zagzebski, James A
2006-01-01
The frequency-dependent complex moduli of human uterine tissue have been characterized. Quantification of the modulus is required for developing uterine ultrasound elastography as a viable imaging modality for diagnosing and monitoring causes for abnormal uterine bleeding and enlargement, as well assessing the integrity of uterine and cervical tissue. The complex modulus was measured in samples from hysterectomies of 24 patients ranging in age from 31 to 79 years. Measurements were done under small compressions of either 1 or 2%, at low pre-compression values (either 1 or 2%), and over a frequency range of 0.1-100 Hz. Modulus values of cervical tissue monotonically increased from approximately 30-90 kPa over the frequency range. Normal uterine tissue possessed modulus values over the same range, while leiomyomas, or uterine fibroids, exhibited values ranging from approximately 60-220 kPa
Arithmetic convergent sequence space defined by modulus function
Directory of Open Access Journals (Sweden)
Taja Yaying
2019-10-01
Full Text Available The aim of this article is to introduce the sequence spaces $AC(f$ and $AS(f$ using arithmetic convergence and modulus function, and study algebraic and topological properties of this space, and certain inclusion results.
Resilient Modulus Characterization of Alaskan Granular Base Materials
2010-08-01
Resilient modulus (MR) of base course material is an important material input for : pavement design. In Alaska, due to distinctiveness of local climate, material source, : fines content and groundwater level, resilient properties of D-1 granular base...
Effect of Cooling Rate on the Longitudinal Modulus of Cu3Sn Phase of Ag-Sn-Cu Amalgam Alloy (Part II
Directory of Open Access Journals (Sweden)
R. H. Rusli
2015-10-01
Full Text Available Effects of cooling rate (at the time of solidification on the elastic constants of Cu3Sn phase of Ag-Sn-Cu dental amalgam alloy were studied. In this study, three types of alloys were made, with the composition Cu-38-37 wt% Sn by means of casting, where each alloy was subjected to different cooling rate, such as cooling on the air (AC, air blown (AB, and quenched in the water (WQ. X-ray diffraction, metallography, and Scanning Electron Microscopy with Energy Dispersive Spectroscopy studies of three alloys indicated the existence of Cu3Sn phase. Determination of the modulus of elasticity of Cu3Sn (ε phase was carried out by the measurement of longitudinal and transversal waves velocity using ultrasonic technique. The result shows that Cu3Sn (ε phase on AC gives higher modulus of elasticity values than those of Cu3Sn (ε on AB and WQ. The high modulus of elasticity value will produce a strong Ag-Sn-Cu dental amalagam alloy.
Elastic properties and electron transport in InAs nanowires
Energy Technology Data Exchange (ETDEWEB)
Migunov, Vadim
2013-02-22
The electron transport and elastic properties of InAs nanowires grown by chemical vapor deposition on InAs (001) substrate were studied experimentally, in-situ in a transmission electron microscope (TEM). A TEM holder allowing the measurement of a nanoforce while simultaneous imaging nanowire bending was used. Diffraction images from local areas of the wire were recorded to correlate elastic properties with the atomic structure of the nanowires. Another TEM holder allowing the application of electrical bias between the nanowire and an apex of a metallic needle while simultaneous imaging the nanowire in TEM or performing electron holography was used to detect mechanical vibrations in mechanical study or holographical observation of the nanowire inner potential in the electron transport studies. The combination of the scanning probe methods with TEM allows to correlate the measured electric and elastic properties of the nanowires with direct identification of their atomic structure. It was found that the nanowires have different atomic structures and different stacking fault defect densities that impacts critically on the elastic properties and electric transport. The unique methods, that were applied in this work, allowed to obtain dependencies of resistivity and Young's modulus of left angle 111 right angle -oriented InAs nanowires on defect density and diameter. It was found that the higher is the defect density the higher are the resistivity and the Young's modulus. Regarding the resistivity, it was deduced that the stacking faults increase the scattering of the electrons in the nanowire. These findings are consistent with the literature, however, the effect described by the other groups is not so pronounced. This difference can be attributed to the significant incompleteness of the physical models used for the data analysis. Regarding the elastic modulus, there are several mechanisms affecting the elasticity of the nanowires discussed in the thesis. It
Durgesh, B. H.; Alkheraif, A. A.; Al Sharawy, M.; Varrela, J.; Vallittu, P. K.
2016-01-01
The aim of this study was to investigate the magnitude of debonding stress of an orthodontic bracket bonded to the enamel with resin systems having different elastic properties. For the same purpose, sixty human premolars were randomly divided into four groups according to the adhesive system used for bonding brackets: G Fix flowable resin (GFI) with Everstick NET (ESN), GFI, G Aenial Universal Flow (GAU) with ESN, and GAU. The brackets were stressed in the occlusogingival direction on a universal testing machine. The values of debonding load and displacement were determined at the point of debonding. The elastic modulus of the tested materials was determined using nanoindentation. An analysis of variance showed a significant difference in the loads required to debond the bracket among the groups tested. The GAU group had the highest elastic modulus, followed by the GFI and ESN groups. ARI (Adhesive Remnant Index) scores demonstrated more remnants of the adhesive material on the bracket surface with adhesives having a higher elastic modulus. Taking into consideration results of the present in-vitro study, it can be concluded that the incorporation of a glass-fiber-reinforced composite resin (FRC) with a low elastic modulus between the orthodontic bracket and enamel increases the debonding force and strain more than with adhesive systems having a higher elastic modulus.
Non-toxic invert analog glass compositions of high modulus
Bacon, J. F. (Inventor)
1974-01-01
Glass compositions having a Young's modulus of at least 15 million psi are described. They and a specific modulus of at least 110 million inches consist essentially of, in mols, 15 to 40% SiO2, 6 to 15% Li2O, 24 to 45% of at least two bivalent oxides selected from the group consisting of Ca, NzO, MgO and CuO; 13 to 39% of at least two trivalent oxides selected from the group consisting of Al2O3, Fe2O3, B2O3, La2O3, and Y2O3 and up to 15% of one or more tetravelent oxides selected from the group consisting of ZrO2, TiO2 and CeO2. The high modulus, low density glass compositions contain no toxic elements. The composition, glass density, Young's modulus, and specific modulus for 28 representative glasses are presented. The fiber modulus of five glasses are given.
Elastic characteristics and microplastic deformation of amorphous alloys on iron base
International Nuclear Information System (INIS)
Pol'dyaeva, G.P.; Zakharov, E.K.; Ovcharov, V.P.; Tret'yakov, B.N.
1983-01-01
Investigation results of elasticity and microplasticity properties (modulus of normal elasticity E, elasticity limit σsub(0.01) and yield limit σsub(0.2)) of three amorphous alloys on iron base Fe 80 B 20 , Fe 70 Cr 10 B 20 and Fe 70 Cr 5 Ni 5 B 20 are given. Amorphous band of the alloys is obtained using the method of melt hardening. It is shown that amorphous alloys on iron base possess high elasticity and yield limits and hardness and are very perspective for the use as spring materials
Elastic characteristics and microplastic deformation of amorphous alloys on iron base
Energy Technology Data Exchange (ETDEWEB)
Pol' dyaeva, G.P.; Zakharov, E.K.; Ovcharov, V.P.; Tret' yakov, B.N. (Tsentral' nyj Nauchno-Issledovatel' skij Inst. Chernoj Metallurgii, Moscow (USSR))
1983-01-01
Investigation results of elasticity and microplasticity properties (modulus of normal elasticity E, elasticity limit sigmasub(0.01) and yield limit sigmasub(0.2)) of three amorphous alloys on iron base Fe/sub 80/B/sub 20/, Fe/sub 70/Cr/sub 10/B/sub 20/ and Fe/sub 70/Cr/sub 5/Ni/sub 5/B/sub 20/ are given. Amorphous band of the alloys is obtained using the method of melt hardening. It is shown that amorphous alloys on iron base possess high elasticity and yield limits and hardness and are very perspective for the use as spring materials.
Defect-dependent elasticity: Nanoindentation as a probe of stress state
International Nuclear Information System (INIS)
Jarausch, K. F.; Kiely, J. D.; Houston, J. E.; Russell, P. E.
2000-01-01
Using an interfacial force microscope, the measured elastic response of 100-nm-thick Au films was found to be strongly correlated with the films' stress state and thermal history. Large, reversible variations (2x) of indentation modulus were recorded as a function of applied stress. Low-temperature annealing caused permanent changes in the films' measured elastic properties. The measured elastic response was also found to vary in close proximity to grain boundaries in thin films and near surface steps on single-crystal surfaces. These results demonstrate a complex interdependence of stress state, defect structure, and elastic properties in thin metallic films. (c) 2000 Materials Research Society
Thermodynamics and elastic properties of Ir from first-principle calculations
International Nuclear Information System (INIS)
Li Qiang; Huang Duohui; Cao Qilong; Wang Fanhou
2013-01-01
Within the framework of the quasiharmonic approximation, the thermodynamics and elastic properties, including phonon dispersion curves, equation of state, linear thermal expansion coefficient and temperature-dependent entropy, enthalpy, heat capacity, elastic constants, bulk modulus, shear modulus, Young's modulus of Ir have been studied using first-principles projector-augmented wave method. The results revealed that the predicted phonon dispersion curves of Ir are in agreement with the experimental measurements by neutron diffractions. Considering the thermal electronic contribution to Helmholtz free energy, the calculated entropy, enthalpy, heat capacity and linear thermal expansion co- efficient from the first-principle are consistent well with the experimental data. At 2600 K, the electronic heat capacity accounts for 17% of the total heat capacity at constant pressure, thus the thermal electronic contribution to Helmholtz free energy is very important. The predicted elastic constants, bulk modulus, shear modulus and Young's modulus at room temperature are also in agreement with the available measurements and increase with the increasing temperature. (authors)
Elasticity and inelasticity of silicon nitride/boron nitride fibrous monoliths.
Energy Technology Data Exchange (ETDEWEB)
Smirnov, B. I.; Burenkov, Yu. A.; Kardashev, B. K.; Singh, D.; Goretta, K. C.; de Arellano-Lopez, A. R.; Energy Technology; Russian Academy of Sciences; Univer. de Sevilla
2001-01-01
A study is reported on the effect of temperature and elastic vibration amplitude on Young's modulus E and internal friction in Si{sub 3}N{sub 4} and BN ceramic samples and Si{sub 3}N{sub 4}/BN monoliths obtained by hot pressing of BN-coated Si{sub 3}N{sub 4} fibers. The fibers were arranged along, across, or both along and across the specimen axis. The E measurements were carried out under thermal cycling within the 20-600 C range. It was found that high-modulus silicon-nitride specimens possess a high thermal stability; the E(T) dependences obtained under heating and cooling coincide well with one another. The low-modulus BN ceramic exhibits a considerable hysteresis, thus indicating evolution of the defect structure under the action of thermoelastic (internal) stresses. Monoliths demonstrate a qualitatively similar behavior (with hysteresis). This behavior of the elastic modulus is possible under microplastic deformation initiated by internal stresses. The presence of microplastic shear in all the materials studied is supported by the character of the amplitude dependences of internal friction and the Young's modulus. The experimental data obtained are discussed in terms of a model in which the temperature dependences of the elastic modulus and their features are accounted for by both microplastic deformation and nonlinear lattice-atom vibrations, which depend on internal stresses.
International Nuclear Information System (INIS)
Li Hua; Ng, Teng Yong; Yew, Yong Kin
2009-01-01
Modeling is conducted in this paper for analysis of the influence of Young's modulus on the response of soft active hydrogels to environmental solution pH changes. A chemo–electro–mechanical formulation termed the multi-effect-coupling pH-stimulus (MECpH) model, which was developed previously according to linear elastic theory for small deformation description, is improved in this paper through incorporation of the finite deformation formulation into the mechanical equilibrium equation. The model is expressed by coupled nonlinear partial differential equations and solved via the meshless Hermite-cloud method with the modified Newton iteration technique. The improved MECpH model is examined by comparison between the computational and published experimental results. Numerical studies are then done on the influence of Young's modulus on the distributive variations of the diffusive ion concentrations and electric potential, and on the deformation variations of the pH-stimulus-responsive hydrogels within different buffered solutions
Energy Technology Data Exchange (ETDEWEB)
Rouhi, Saeed, E-mail: s_rouhi@iaul.ac.ir
2017-05-15
In this paper, the mechanical properties of the R-graphynes are investigated by using molecular dynamics simulations. For this purpose, the uniaxial strain is applied on the nanosheets. The effects of R-graphyne chirality and dimension on their fracture and elastic properties are investigated. It is shown that the fracture properties of the armchair R-graphyne are approximately independent from the nanosheet sizes. However, a clear dependence is observed in the fracture properties of the zigzag R-graphyne on the nanosheet dimensions. Comparing the elastic modulus of the armchair and zigzag R-graphynes, it is shown that for the same sizes, the elastic modulus of armchair R-graphyne is approximately equal to 2.5 times of the elastic modulus of the zigzag ones. Pursuing the fracture process of R-graphynes with different chiralities, it is represented that the fracture propagates in the zigzag nanosheet with a higher velocity than the armchair ones.
Structures and Elastic Moduli of Polymer Nanocomposite Thin Films
Yuan, Hongyi; Karim, Alamgir; University of Akron Team
2014-03-01
Polymeric thin films generally possess unique mechanical and thermal properties due to confinement. In this study we investigated structures and elastic moduli of polymer nanocomposite thin films, which can potentially find wide applications in diverse areas such as in coating, permeation and separation. Conventional thermoplastics (PS, PMMA) and biopolymers (PLA, PCL) were chosen as polymer matrices. Various types of nanoparticles were used including nanoclay, fullerene and functionalized inorganic particles. Samples were prepared by solvent-mixing followed by spin-coating or flow-coating. Film structures were characterized using X-ray scattering and transmission electron microscopy. Elastic moduli were measured by strain-induced elastic buckling instability for mechanical measurements (SIEBIMM), and a strengthening effect was found in certain systems due to strong interaction between polymers and nanoparticles. The effects of polymer structure, nanoparticle addition and film thickness on elastic modulus will be discussed and compared with bulk materials.
Radiation processed composite materials of wood and elastic polyester resins
International Nuclear Information System (INIS)
Tapolcai, I.; Czvikovszky, T.
1983-01-01
The radiation polymerization of multifunctional unsaturated polyester-monomer mixtures in wood forms interpenetrating network system. The mechanical resistance (compression, abrasion, hardness, etc.) of these composite materials are generally well over the original wood, however the impact strength is almost the same or even reduced, in comparison to the wood itself. An attempt is made using elastic polyester resins to produced wood-polyester composite materials with improved modulus of elasticity and impact properties. For the impregnation of European beech wood two types of elastic unsaturated polyester resins were used. The exothermic effect of radiation copolymerization of these resins in wood has been measured and the dose rate effects as well as hardening dose was determined. Felxural strength and impact properties were examined. Elastic unsaturated polyester resins improved the impact strength of wood composite materials. (author)
Elastic response of thermal spray deposits under indentation tests
International Nuclear Information System (INIS)
Leigh, S.H.; Lin, C.K.; Berndt, C.C.
1997-01-01
The elastic response behavior of thermal spray deposits at Knoop indentations has been investigated using indentation techniques. The ration of hardness to elastic modulus, which is an important prerequisite for the evaluation of indentation fracture toughness, is determined by measuring the elastic recovery of the in-surface dimensions of Knoop indentations. The elastic moduli of thermal spray deposits are in the range of 12%--78% of the comparable bulk materials and reveal the anisotropic behavior of thermal spray deposits. A variety of thermal spray deposits has been examined, including Al 2 O 3 , yttria-stabilized ZrO 2 (YSZ), and NiAl. Statistical tools have been used to evaluate the error estimates of the data
DEFF Research Database (Denmark)
Spichkin, Y.I.; Bohr, Jakob; Tishin, A.M.
1996-01-01
The temperature dependence of the Young modulus along the crystallographic axes b and c (E(b) and E(c)), and the internal friction of a terbium single crystal have been measured. At 4.2 K, E(b) and E(c) are equal to 38 and 84.5 GPa, respectively. The lattice part of the Young modulus and the Debye...... temperature has been calculated. The origin of the Young modulus anomalies arising at the transition to the magnetically ordered state is discussed....
Young's modulus of BF wood material by longitudinal vibration
International Nuclear Information System (INIS)
Phadke, Sushil; Shrivastava, Bhakt Darshan; Mishra, Ashutosh; Dagaonkar, N
2014-01-01
All engineered structures are designed and built with consideration of resisting the same fundamental forces of tension, compression, shear, bending and torsion. Structural design is a balance of these internal and external forces. So, it is interesting to calculate the Young's moduli of Borassus Flabellifier BF wood are quite important from the application point of view. The ultrasonic waves are closely related with the elastic and inelastic properties of the materials. In the present study, we measured longitudinal wave ultrasonic velocities in BF wood material by longitudinal vibration method. After measuring ultrasonic velocity in BF wood material, we calculated Young's modulus of Borassus Flabellifier BF wood material. We used ultrasonic interferometer for measuring longitudinal wave ultrasonic velocity in BF wood material made by Mittal Enterprises, New Delhi, India in our laboratory. Borassus Flabellifier BF wood material was collected from Dhar district of Madhya Pradesh, India.
Quasi-elastic high-pressure waves in 2024 Al and Cu
International Nuclear Information System (INIS)
Morris, C.E.; Fritz, J.N.; Holian, B.L.
1981-01-01
Release waves from the back of a plate slap experiment are used to estimate the longitudinal modulus, bulk modulus and shear strength of the metal in the state produced by a symmetric collision. The velocity of the interface between the metal target and a window material is measured by the axially symmetric magnetic (ASM) probe. Wave profiles for initial states up to 90 GPa for 2024 Al and up to 150 GPa for Cu have been obtained. Elastic perfectly-plastic (EPP) theory cannot account for the results. A relatively simple quasi-elastic plastic (QEP) model can
Elastic properties of cubic perovskite BaRuO{sub 3} from first-principles calculations
Energy Technology Data Exchange (ETDEWEB)
Han Deming; Liu Xiaojuan; Lv Shuhui; Li Hongping [State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China); Meng Jian, E-mail: jmeng@ciac.jl.c [State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China)
2010-08-01
We present first-principles investigations on the structural and elastic properties of the cubic perovskite BaRuO{sub 3} using density-functional theory within both local density approximation (LDA) and generalized gradient approximation (GGA). Basic physical properties, such as lattice constant, shear modulus, elastic constants (C{sub ij}) are calculated. The calculated energy band structures show that the cubic perovskite BaRuO{sub 3} is metallic. We have also predicted the Young's modulus (Y), Poisson's ratio ({upsilon}), and Anisotropy factor (A).
International Nuclear Information System (INIS)
Zheng, Y P; Choi, A P C; Ling, H Y; Huang, Y P
2009-01-01
Indentation is commonly used to determine the mechanical properties of different kinds of biological tissues and engineering materials. With the force–deformation data obtained from an indentation test, Young's modulus of the tissue can be calculated using a linear elastic indentation model with a known Poisson's ratio. A novel method for simultaneous estimation of Young's modulus and Poisson's ratio of the tissue using a single indentation was proposed in this study. Finite element (FE) analysis using 3D models was first used to establish the relationship between Poisson's ratio and the deformation-dependent indentation stiffness for different aspect ratios (indentor radius/tissue original thickness) in the indentation test. From the FE results, it was found that the deformation-dependent indentation stiffness linearly increased with the deformation. Poisson's ratio could be extracted based on the deformation-dependent indentation stiffness obtained from the force–deformation data. Young's modulus was then further calculated with the estimated Poisson's ratio. The feasibility of this method was demonstrated in virtue of using the indentation models with different material properties in the FE analysis. The numerical results showed that the percentage errors of the estimated Poisson's ratios and the corresponding Young's moduli ranged from −1.7% to −3.2% and 3.0% to 7.2%, respectively, with the aspect ratio (indentor radius/tissue thickness) larger than 1. It is expected that this novel method can be potentially used for quantitative assessment of various kinds of engineering materials and biological tissues, such as articular cartilage
Calculating tissue shear modulus and pressure by 2D log-elastographic methods
International Nuclear Information System (INIS)
McLaughlin, Joyce R; Zhang, Ning; Manduca, Armando
2010-01-01
Shear modulus imaging, often called elastography, enables detection and characterization of tissue abnormalities. In this paper the data are two displacement components obtained from successive MR or ultrasound data sets acquired while the tissue is excited mechanically. A 2D plane strain elastic model is assumed to govern the 2D displacement, u. The shear modulus, μ, is unknown and whether or not the first Lamé parameter, λ, is known the pressure p = λ∇ . u which is present in the plane strain model cannot be measured and is unreliably computed from measured data and can be shown to be an order one quantity in the units kPa. So here we present a 2D log-elastographic inverse algorithm that (1) simultaneously reconstructs the shear modulus, μ, and p, which together satisfy a first-order partial differential equation system, with the goal of imaging μ; (2) controls potential exponential growth in the numerical error and (3) reliably reconstructs the quantity p in the inverse algorithm as compared to the same quantity computed with a forward algorithm. This work generalizes the log-elastographic algorithm in Lin et al (2009 Inverse Problems 25) which uses one displacement component, is derived assuming that the component satisfies the wave equation and is tested on synthetic data computed with the wave equation model. The 2D log-elastographic algorithm is tested on 2D synthetic data and 2D in vivo data from Mayo Clinic. We also exhibit examples to show that the 2D log-elastographic algorithm improves the quality of the recovered images as compared to the log-elastographic and direct inversion algorithms
Low modulus and bioactive Ti/α-TCP/Ti-mesh composite prepared by spark plasma sintering.
Guo, Yu; Tan, Yanni; Liu, Yong; Liu, Shifeng; Zhou, Rui; Tang, Hanchun
2017-11-01
A titanium mesh scaffold composite filled with Ti/α-TCP particles was prepared by spark plasma sintering (SPS). The microstructures and interfacial reactions of the composites were investigated by scanning electron microscopy (SEM), Energy Dispersive Spectroscopy (EDS) and X-ray diffraction (XRD) analyses. The compressive strength and elastic modulus were also measured. In vitro bioactivity and biocompatibility was evaluated by using simulated body fluid and cells culture, respectively. After high temperature sintering, Ti oxides, Ti x P y and CaTiO 3 were formed. The formation of Ti oxides and Ti x P y were resulted from the diffusion of O and P elements from α-TCP to Ti. CaTiO 3 was the reaction product of Ti and α-TCP. The composite of 70Ti/α-TCP incorporated with Ti mesh showed a high compressive strength of 589MPa and a low compressive modulus of 30GPa. The bioactivity test showed the formation of a thick apatite layer on the composite and well-spread cells attachment. A good combination of mechanical properties and bioactivity indicated a high potential application of Ti/α-TCP/Ti-mesh composite for orthopedic implants. Copyright © 2017. Published by Elsevier B.V.
Zhang, Zuhua; Wang, Hao
2016-08-01
The pore characteristics of GFCs manufactured in the laboratory with 0-16% foam additions were examined using image analysis (IA) and vacuum water saturation techniques. The pore size distribution, pore shape and porosity were obtained. The IA method provides a suitable approach to obtain the information of large pores, which are more important in affecting the compressive strength of GFC. By examining the applicability of the existing models of predicting compressive strength of foam concrete, a modified Ryshkevitch’s model is proposed for GFC, in which only the porosity that is contributed by the pores over a critical diameter (>100 μm) is considered. This “critical void model” is shown to have very satisfying prediction capability in the studied range of porosity. A compression-modulus model for Portland cement concrete is recommended for predicting the compression modulus elasticity of GFC. This study confirms that GFC have similar pore structures and mechanical behavior as those Portland cement foam concrete and can be used alternatively in the industry for the construction and insulation purposes.
Equivalent Young's modulus of composite resin for simulation of stress during dental restoration.
Park, Jung-Hoon; Choi, Nak-Sam
2017-02-01
For shrinkage stress simulation in dental restoration, the elastic properties of composite resins should be acquired beforehand. This study proposes a formula to measure the equivalent Young's modulus of a composite resin through a calculation scheme of the shrinkage stress in dental restoration. Two types of composite resins remarkably different in the polymerization shrinkage strain were used for experimental verification: the methacrylate-type (Clearfil AP-X) and the silorane-type (Filtek P90). The linear shrinkage strains of the composite resins were gained through the bonded disk method. A formula to calculate the equivalent Young's moduli of composite resin was derived on the basis of the restored ring substrate. Equivalent Young's moduli were measured for the two types of composite resins through the formula. Those values were applied as input to a finite element analysis (FEA) for validation of the calculated shrinkage stress. Both of the measured moduli through the formula were appropriate for stress simulation of dental restoration in that the shrinkage stresses calculated by the FEA were in good agreement within 3.5% with the experimental values. The concept of equivalent Young's modulus so measured could be applied for stress simulation of 2D and 3D dental restoration. Copyright © 2016 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.
Structural aspects of elastic deformation of a metallic glass
International Nuclear Information System (INIS)
Hufnagel, T. C.; Ott, R. T.; Almer, J.
2006-01-01
We report the use of high-energy x-ray scattering to measure strain in a Zr 57 Ti 5 Cu 20 Ni 8 Al 10 bulk metallic glass in situ during uniaxial compression in the elastic regime up to stresses of approximately 60% of the yield stress. The strains extracted in two ways--directly from the normalized scattering data and from the pair correlation functions--are in good agreement with each other for length scales greater than 4 A. The elastic modulus calculated on the basis of this strain is in good agreement with that reported for closely related amorphous alloys based on macroscopic measurements. The strain measured for atoms in the nearest-neighbor shell, however, is smaller than that for more distant shells, and the effective elastic modulus calculated from the strain on this scale is therefore larger, comparable to crystalline alloys of similar composition. These observations are in agreement with previously proposed models in which the nominally elastic deformation of a metallic glass has a significant anelastic component due to atomic rearrangements in topologically unstable regions of the structure. We also observe that the distribution of the atomic-level stresses in the glass becomes more uniform during loading. This implies that the stiffness of metallic glasses may have an entropic contribution, analogous to the entropic contribution in rubber elasticity
Size dependence of elastic mechanical properties of nanocrystalline aluminum
Energy Technology Data Exchange (ETDEWEB)
Xu, Wenwu; Dávila, Lilian P., E-mail: ldavila@ucmerced.edu
2017-04-24
The effect of grain size on the elastic mechanical properties of nanocrystalline pure metal Al is quantified by molecular dynamics simulation method. In this work, the largest nanocrystalline Al sample has a mean grain size of 29.6 nm and contains over 100 millions atoms in the modeling system. The simulation results show that the elastic properties including elastic modulus and ultimate tensile strength of nanocrystalline Al are relatively insensitive to the variation of mean grain size above 13 nm yet they become distinctly grain size dependent below 13 nm. Moreover, at a grain size <13 nm, the elastic modulus decreases monotonically with decreasing grain size while the ultimate tensile strength of nanocrystalline Al initially decreases with the decrease of the grain size down to 9 nm and then increases with further reduction of grain size. The increase of ultimate tensile strength below 9 nm is believed to be a result of an extended elasticity in the ultrafine grain size nanocrystalline Al. This study can facilitate the prediction of varied mechanical properties for similar nanocrystalline materials and even guide testing and fabrication schemes of such materials.
Influence of Elastic Anisotropy on Extended Dislocation Nodes
Energy Technology Data Exchange (ETDEWEB)
Pettersson, B
1971-09-15
The interaction forces between the partial dislocations forming an extended dislocation node are calculated using elasticity theory for anisotropic media.s are carried out for nodes of screw, edge and mixed character in Ag, which has an anisotropy ratio A equal to 3, and in a hypothetic material with A = 1 and the same shear modulus as Ag. The results are compared with three previous theories using isotropic elasticity theory. As expected, in Ag the influence of anisotropy is of the same order as the uncertainty due to the dislocation core energy
Dynamic response of beams on elastic foundations to impact loading
International Nuclear Information System (INIS)
Prasad, B.B.; Sinha, B.P.
1987-01-01
The beam considered is a Timoshenko beam in which the effects of rotatory inertia and shear deformations are included and the foundation model consists of Winkler-Zimmermann type having Hookean linear elastic springs. The analysis is very useful for predicting the dynamic response of structural components of aircraft or nuclear reactors or even runways if that component may be mathematically idealized as a beam on elastic foundation. The effect of rotatory inertia and shear deformation is very much pronounced and hence should not be neglected in solving such impact problems. In general the effect of foundation modulus is to further increase the values of frequencies of vibrations. (orig./HP)
Modeling dynamic acousto-elastic testing experiments: validation and perspectives.
Gliozzi, A S; Scalerandi, M
2014-10-01
Materials possessing micro-inhomogeneities often display a nonlinear response to mechanical solicitations, which is sensitive to the confining pressure acting on the sample. Dynamic acoustoelastic testing allows measurement of the instantaneous variations in the elastic modulus due to the change of the dynamic pressure induced by a low-frequency wave. This paper shows that a Preisach-Mayergoyz space based hysteretic multi-state elastic model provides an explanation for experimental observations in consolidated granular media and predicts memory and nonlinear effects comparable to those measured in rocks.
Elastic properties of various ceramic materials
International Nuclear Information System (INIS)
Zimmermann, H.
1992-09-01
The Young's modulus and the Poisson's ratio of various ceramics have been investigated at room temperature and compared with data from the literature. The ceramic materials investigated are Al 2 O 3 , Al 2 O 3 -ZrO 2 , MgAl 2 O 4 , LiAlO 2 , Li 2 SiO 3 , Li 4 SiO 4 , UO 2 , AlN, SiC, B 4 C, TiC, and TiB 2 . The dependence of the elastic moduli on porosity and temperature have been reviewed. Measurements were also performed on samples of Al 2 O 3 , AlN, and SiC, which had been irradiated to maximum neutron fluences of 1.6.10 26 n/m 2 (E>0.1 MeV) at different temperatures. The Young's modulus is nearly unaffected at fluences up to about 4.10 24 n/m 2 . However, it decreases with increasing neutron fluence and seems to reach a saturation value depending upon the irradiation temperature. The reduction of the Young's modulus is lowest in SiC. (orig.) [de
Variable modulus cellular structures using pneumatic artificial muscles
Pontecorvo, Michael E.; Niemiec, Robert J.; Gandhi, Farhan S.
2014-04-01
This paper presents a novel variable modulus cellular structure based on a hexagonal unit cell with pneumatic artificial muscle (PAM) inclusions. The cell considered is pin-jointed, loaded in the horizontal direction, with three PAMs (one vertical PAM and two horizontal PAMs) oriented in an "H" configuration between the vertices of the cell. A method for calculation of the hexagonal cell modulus is introduced, as is an expression for the balance of tensile forces between the horizontal and vertical PAMs. An aluminum hexagonal unit cell is fabricated and simulation of the hexagonal cell with PAM inclusions is then compared to experimental measurement of the unit cell modulus in the horizontal direction with all three muscles pressurized to the same value over a pressure range up to 758 kPa. A change in cell modulus by a factor of 1.33 and a corresponding change in cell angle of 0.41° are demonstrated experimentally. A design study via simulation predicts that differential pressurization of the PAMs up to 2068 kPa can change the cell modulus in the horizontal direction by a factor of 6.83 with a change in cell angle of only 2.75°. Both experiment and simulation show that this concept provides a way to decouple the length change of a PAM from the change in modulus to create a structural unit cell whose in-plane modulus in a given direction can be tuned based on the orientation of PAMs within the cell and the pressure supplied to the individual muscles.
Growth-induced axial buckling of a slender elastic filament embedded in an isotropic elastic matrix
O'Keeffe, Stephen G.
2013-11-01
We investigate the problem of an axially loaded, isotropic, slender cylinder embedded in a soft, isotropic, outer elastic matrix. The cylinder undergoes uniform axial growth, whilst both the cylinder and the surrounding elastic matrix are confined between two rigid plates, so that this growth results in axial compression of the cylinder. We use two different modelling approaches to estimate the critical axial growth (that is, the amount of axial growth the cylinder is able to sustain before it buckles) and buckling wavelength of the cylinder. The first approach treats the filament and surrounding matrix as a single 3-dimensional elastic body undergoing large deformations, whilst the second approach treats the filament as a planar, elastic rod embedded in an infinite elastic foundation. By comparing the results of these two approaches, we obtain an estimate of the foundation modulus parameter, which characterises the strength of the foundation, in terms of the geometric and material properties of the system. © 2013 Elsevier Ltd. All rights reserved.
Global model for the lithospheric strength and effective elastic thickness
Magdala Tesauro; Mikhail Kaban; S. A. P. L. Cloetingh
2013-01-01
Global distribution of the strength and effective elastic thickness (Te) of the lithosphere are estimated using physical parameters from recent crustal and lithospheric models. For the Te estimation we apply a new approach, which provides a possibility to take into account variations of Young modulus (E) within the lithosphere. In view of the large uncertainties affecting strength estimates, we evaluate global strength and Te distributions for possible end-member ‘hard’ (HRM) and a ‘soft’ (SR...
Young’s modulus evaluation and thermal shock behavior of a porous SiC/cordierite composite material
Directory of Open Access Journals (Sweden)
Pošarac-Marković M.
2015-01-01
Full Text Available Porous SiC/Cordierite Composite Material with graphite content (10% was synthesized. Evaluation of Young modulus of elasticity and thermal shock behavior of these samples was presented. Thermal shock behavior was monitored using water quench test, and non destructive methods such are UPVT and image analysis were also used for accompaniment the level of destruction of the samples during water quench test. Based on the level of destruction graphical modeling of critical number of cycles was given. This approach was implemented on discussion of the influence of the graphite content on thermal stability behavior of the samples. [Projekat Ministarstva nauke Republike Srbije, br. III 45012
WE-E-9A-01: Ultrasound Elasticity
Energy Technology Data Exchange (ETDEWEB)
Emelianov, S [University of Texas at Austin, Austin, TX (United States); Hall, T [University of WI-Madison, Madison, WI (United States); Bouchard, R [UT MD Anderson Cancer Center and UTHSC at Houston Graduate School of Biomed, Houston, TX (United States)
2014-06-15
Principles and techniques of ultrasound-based elasticity imaging will be presented, including quasistatic strain imaging, shear wave elasticity imaging, and their implementations in available systems. Deeper exploration of quasistatic methods, including elastic relaxation, and their applications, advantages, artifacts and limitations will be discussed. Transient elastography based on progressive and standing shear waves will be explained in more depth, along with applications, advantages, artifacts and limitations, as will measurement of complex elastic moduli. Comparisons will be made between ultrasound radiation force techniques, MR elastography, and the simple A mode plus mechanical plunger technique. Progress in efforts, such as that by the Quantitative Imaging Biomarkers Alliance, to reduce the differences in the elastic modulus reported by different commercial systems will be explained. Dr. Hall is on an Advisory Board for Siemens Ultrasound and has a research collaboration with them, including joint funding by R01CA140271 for nonlinear elasticity imaging. Learning Objectives: Be reminded of the long history of palpation of tissue elasticity for critical medical diagnosis and the relatively recent advances to be able to image tissue strain in response to an applied force. Understand the differences between shear wave speed elasticity measurement and imaging and understand the factors affecting measurement and image frame repletion rates. Understand shear wave propagation effects that can affect measurements, such as essentially lack of propagation in fluids and boundary effects, so important in thin layers. Know characteristics of available elasticity imaging phantoms, their uses and limitations. Understand thermal and cavitational limitations affecting radiation force-based shear wave imaging. Have learning and references adequate to for you to use in teaching elasticity imaging to residents and technologists. Be able to explain how elasticity measurement
WE-E-9A-01: Ultrasound Elasticity
International Nuclear Information System (INIS)
Emelianov, S; Hall, T; Bouchard, R
2014-01-01
Principles and techniques of ultrasound-based elasticity imaging will be presented, including quasistatic strain imaging, shear wave elasticity imaging, and their implementations in available systems. Deeper exploration of quasistatic methods, including elastic relaxation, and their applications, advantages, artifacts and limitations will be discussed. Transient elastography based on progressive and standing shear waves will be explained in more depth, along with applications, advantages, artifacts and limitations, as will measurement of complex elastic moduli. Comparisons will be made between ultrasound radiation force techniques, MR elastography, and the simple A mode plus mechanical plunger technique. Progress in efforts, such as that by the Quantitative Imaging Biomarkers Alliance, to reduce the differences in the elastic modulus reported by different commercial systems will be explained. Dr. Hall is on an Advisory Board for Siemens Ultrasound and has a research collaboration with them, including joint funding by R01CA140271 for nonlinear elasticity imaging. Learning Objectives: Be reminded of the long history of palpation of tissue elasticity for critical medical diagnosis and the relatively recent advances to be able to image tissue strain in response to an applied force. Understand the differences between shear wave speed elasticity measurement and imaging and understand the factors affecting measurement and image frame repletion rates. Understand shear wave propagation effects that can affect measurements, such as essentially lack of propagation in fluids and boundary effects, so important in thin layers. Know characteristics of available elasticity imaging phantoms, their uses and limitations. Understand thermal and cavitational limitations affecting radiation force-based shear wave imaging. Have learning and references adequate to for you to use in teaching elasticity imaging to residents and technologists. Be able to explain how elasticity measurement
Elastic scattering and quasi-elastic transfers
International Nuclear Information System (INIS)
Mermaz, M.C.
1978-01-01
Experiments are presented which it will be possible to carry out at GANIL on the elastic scattering of heavy ions: diffraction phenomena if the absorption is great, refraction phenomena if absorption is low. The determination of the optical parameters can be performed. The study of the quasi-elastic transfer reactions will make it possible to know the dynamics of the nuclear reactions, form exotic nuclei and study their energy excitation spectrum, and analyse the scattering and reaction cross sections [fr
International Nuclear Information System (INIS)
Rosinger, H.E.; Ritchie, I.G.; Shillinglaw, A.J.
1975-09-01
This report contains experimentally determined data on the dynamic elastic moduli of zircaloy-2, zircaloy-4, zirconium-2.5wt% niobium and Marz grade crystal bar zirconium. Data on both the dynamic Young's moduli and shear moduli of the alloys have been measured at room temperature and Young's modulus as a function of temperature has been determined over the temperature range 300 K to 1000 K. In every case, Young's modulus decreases linearly with increasing temperature and is expressed by an empirical equation fitted to the data. Differences in Young's modulus values determined from specimens with longitudinal axes parallel and perpendicular to the rolling direction are small, as are the differences between Young's moduli determined from strip, bar stock and fuel sheathing. (author)
The elasticity and failure of fluid-filled cellular solids: theory and experiment.
Warner, M; Thiel, B L; Donald, A M
2000-02-15
We extend and apply theories of filled foam elasticity and failure to recently available data on foods. The predictions of elastic modulus and failure mode dependence on internal pressure and on wall integrity are borne out by photographic evidence of distortion and failure under compressive loading and under the localized stress applied by a knife blade, and by mechanical data on vegetables differing only in their turgor pressure. We calculate the dry modulus of plate-like cellular solids and the cross over between dry-like and fully fluid-filled elastic response. The bulk elastic properties of limp and aging cellular solids are calculated for model systems and compared with our mechanical data, which also show two regimes of response. The mechanics of an aged, limp beam is calculated, thus offering a practical procedure for comparing experiment and theory. This investigation also thereby offers explanations of the connection between turgor pressure and crispness and limpness of cellular materials.
The elasticity and failure of fluid-filled cellular solids: Theory and experiment
Warner, M.; Thiel, B. L.; Donald, A. M.
2000-02-01
We extend and apply theories of filled foam elasticity and failure to recently available data on foods. The predictions of elastic modulus and failure mode dependence on internal pressure and on wall integrity are borne out by photographic evidence of distortion and failure under compressive loading and under the localized stress applied by a knife blade, and by mechanical data on vegetables differing only in their turgor pressure. We calculate the dry modulus of plate-like cellular solids and the cross over between dry-like and fully fluid-filled elastic response. The bulk elastic properties of limp and aging cellular solids are calculated for model systems and compared with our mechanical data, which also show two regimes of response. The mechanics of an aged, limp beam is calculated, thus offering a practical procedure for comparing experiment and theory. This investigation also thereby offers explanations of the connection between turgor pressure and crispness and limpness of cellular materials.
Rubber elasticity for percolation network consisting of Gaussian chains
International Nuclear Information System (INIS)
Nishi, Kengo; Noguchi, Hiroshi; Shibayama, Mitsuhiro; Sakai, Takamasa
2015-01-01
A theory describing the elastic modulus for percolation networks of Gaussian chains on general lattices such as square and cubic lattices is proposed and its validity is examined with simulation and mechanical experiments on well-defined polymer networks. The theory was developed by generalizing the effective medium approximation (EMA) for Hookian spring network to Gaussian chain networks. From EMA theory, we found that the ratio of the elastic modulus at p, G to that at p = 1, G 0 , must be equal to G/G 0 = (p − 2/f)/(1 − 2/f) if the position of sites can be determined so as to meet the force balance, where p is the degree of cross-linking reaction. However, the EMA prediction cannot be applicable near its percolation threshold because EMA is a mean field theory. Thus, we combine real-space renormalization and EMA and propose a theory called real-space renormalized EMA, i.e., REMA. The elastic modulus predicted by REMA is in excellent agreement with the results of simulations and experiments of near-ideal diamond lattice gels
Rubber elasticity for percolation network consisting of Gaussian chains
Energy Technology Data Exchange (ETDEWEB)
Nishi, Kengo, E-mail: kengo.nishi@phys.uni-goettingen.de, E-mail: sakai@tetrapod.t.u-tokyo.ac.jp, E-mail: sibayama@issp.u-tokyo.ac.jp; Noguchi, Hiroshi; Shibayama, Mitsuhiro, E-mail: kengo.nishi@phys.uni-goettingen.de, E-mail: sakai@tetrapod.t.u-tokyo.ac.jp, E-mail: sibayama@issp.u-tokyo.ac.jp [Institute for Solid State Physics, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581 (Japan); Sakai, Takamasa, E-mail: kengo.nishi@phys.uni-goettingen.de, E-mail: sakai@tetrapod.t.u-tokyo.ac.jp, E-mail: sibayama@issp.u-tokyo.ac.jp [Department of Bioengineering, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan)
2015-11-14
A theory describing the elastic modulus for percolation networks of Gaussian chains on general lattices such as square and cubic lattices is proposed and its validity is examined with simulation and mechanical experiments on well-defined polymer networks. The theory was developed by generalizing the effective medium approximation (EMA) for Hookian spring network to Gaussian chain networks. From EMA theory, we found that the ratio of the elastic modulus at p, G to that at p = 1, G{sub 0}, must be equal to G/G{sub 0} = (p − 2/f)/(1 − 2/f) if the position of sites can be determined so as to meet the force balance, where p is the degree of cross-linking reaction. However, the EMA prediction cannot be applicable near its percolation threshold because EMA is a mean field theory. Thus, we combine real-space renormalization and EMA and propose a theory called real-space renormalized EMA, i.e., REMA. The elastic modulus predicted by REMA is in excellent agreement with the results of simulations and experiments of near-ideal diamond lattice gels.
Elastic properties of liquid and solid argon in nanopores
International Nuclear Information System (INIS)
Schappert, Klaus; Pelster, Rolf
2013-01-01
We have measured sorption isotherms and determined the intrinsic longitudinal elastic modulus β Ar,ads of nanoconfined material via ultrasonic measurements combined with a special effective medium analysis. In the liquid regime the adsorbate only contributes to the measured effective properties when the pores are completely filled and the modulus is bulklike. At partial fillings its contribution is cancelled out by the high compressibility of the vapour phase. In contrast, at lower temperatures frozen argon as well as underlying liquid surface layers cause a linear increase of the effective longitudinal modulus upon filling. During sorption the contribution of the liquid surface layers near the pore wall β Ar,surf increases with the thickness of the solid layers reaching the bulk value β Ar,liquid only in the limit of complete pore filling. We interpret this effect as due to the gradual stiffening of the solid argon membrane. The measurements and their analysis show that longitudinal ultrasonic waves are well suited to the study of the elastic properties and liquid–solid phase transitions in porous systems. This method should also help to detect the influence of nanoconfinement on elastic properties in further research. (paper)
Determination of Young's Modulus of Graphene by Raman Spectroscopy
Lee, Jae-Ung; Yoon, Duhee; Cheong, Hyeonsik
2012-02-01
The mechanical properties of graphene are interesting research subjects because its Young's modulus and strength are extremely high. Values of ˜1 TPa for the Young's modulus have been reported [Lee et al. Science, 321, 385 (2008), Koenig et al. Nat. Nanotech. 6, 543 (2011)]. We made a graphene sample on a SiO2/Si substrate with closed-bottom holes by mechanical exfoliation. A pressure difference across the graphene membrane was applied by putting the sample in a vacuum chamber. This pressure difference makes the graphene membrane bulge upward like a balloon. By measuring the shifts of the Raman G and 2D bands, we estimated the amount of strain on the graphene membrane. By comparing the strain estimated from the Raman measurements with numerical simulations based on the finite element method, we obtained the Young's modulus of graphene.
Frequency-dependent complex modulus at the glass transition in Pd40Ni10Cu30P20 bulk amorphous alloys
International Nuclear Information System (INIS)
Lee, M.L.; Li, Y.; Feng, Y.P.; Carter, W.C.
2003-01-01
We report frequency-dependent measurements of the dynamic elastic modulus of a Pd 40 Cu 30 Ni 10 P 20 bulk amorphous phase near its glass transition temperature. The storage and loss moduli exhibit a structural relaxation similar to those observed by other characterization techniques. Parameters obtained by fitting to the Vogel-Fulcher-Tamman equation and the Kohlrausch-Williams-Watts model exhibit similar behaviors to those other methods
International Nuclear Information System (INIS)
Villain, P.; Beauchamp, P.; Badawi, K.F.; Goudeau, P.; Renault, P.-O.
2004-01-01
Equilibrium state and elastic coefficients of nanometre-sized single crystal tungsten layers and wires are investigated by atomistic simulations. The variations of the equilibrium distances as a function of the layer thickness or wire cross-section are mainly due to elastic effects of surface tension forces. A strong decrease of the Young's modulus is observed when the transverse dimensions are reduced below 2-3 nm
International Nuclear Information System (INIS)
Khidirov, I.; Khajdarov, T.
1995-01-01
Elasticity characteristics of cubic and tetragonal phases of titanium nitride in the homogeneity range were studied for the first time by ultrasonic resonance method. It is established that the Young modulus, the shift and volume module of cubic titanium nitride elasticity in the homogeneity range change nonlinearly with decrease in nitrogen concentration and correlate with concentration dependences of other physical properties.15 refs., 2 figs
Structural phase transition and elastic properties of mercury chalcogenides
Energy Technology Data Exchange (ETDEWEB)
Varshney, Dinesh, E-mail: vdinesh33@rediffmail.com [School of Physics, Vigyan Bhavan, Devi Ahilya University, Khandwa Road Campus, Indore 452001 (India); Shriya, S. [School of Physics, Vigyan Bhavan, Devi Ahilya University, Khandwa Road Campus, Indore 452001 (India); Khenata, R. [Laboratoire de Physique Quantique et de Modelisation Mathematique (LPQ3M), Departement de Technologie, Universite de Mascara, 29000 Mascara (Algeria)
2012-08-15
Pressure induced structural transition and elastic properties of ZnS-type (B3) to NaCl-type (B1) structure in mercury chalcogenides (HgX; X = S, Se and Te) are presented. An effective interionic interaction potential (EIOP) with long-range Coulomb, as well charge transfer interactions, Hafemeister and Flygare type short-range overlap repulsion extended up to the second neighbor ions and van der Waals interactions are considered. Emphasis is on the evaluation of the pressure dependent Poisson's ratio {nu}, the ratio R{sub BT/G} of B (bulk modulus) over G (shear modulus), anisotropy parameter, Shear and Young's modulus, Lame constant, Kleinman parameter, elastic wave velocity and thermodynamical property as Debye temperature. The Poisson's ratio behavior infers that Mercury chalcogenides are brittle in nature. To our knowledge this is the first quantitative theoretical prediction of the pressure dependence of elastic and thermodynamical properties explicitly the ductile (brittle) nature of HgX and still awaits experimental confirmations. Highlights: Black-Right-Pointing-Pointer Vast volume discontinuity in phase diagram infers transition from ZnS to NaCl structure. Black-Right-Pointing-Pointer The shear elastic constant C{sub 44} is nonzero confirms the mechanical stability. Black-Right-Pointing-Pointer Pressure dependence of {theta}{sub D} infers the softening of lattice with increasing pressure. Black-Right-Pointing-Pointer Estimated bulk, shear and tetragonal moduli satisfied elastic stability criteria. Black-Right-Pointing-Pointer In both B3 and B1 phases, C{sub 11} and C{sub 12} increase linearly with pressure.
Temperature, Frequency and Young’s Modulus of a Wineglass
Directory of Open Access Journals (Sweden)
Amitta Miller
2015-01-01
Full Text Available A crystal soda-lime wineglass, heated to temperatures ranging from 25 °C to 150 °C, was tapped and the frequency recorded. It was shown that the relative change in the frequency at different temperatures can be used to determine the effect of temperature on Young’s Modulus of the glass. This simple method of tapping a wineglass is proposed as an effective way of determining the relative effect of temperature on Young’ Modulus of glass.
Paro, Alberto
2013-01-01
Written in an engaging, easy-to-follow style, the recipes will help you to extend the capabilities of ElasticSearch to manage your data effectively.If you are a developer who implements ElasticSearch in your web applications, manage data, or have decided to start using ElasticSearch, this book is ideal for you. This book assumes that you've got working knowledge of JSON and Java
Christopher G. Surfleet; Arne Skaugset; Brian Dietterick
2012-01-01
The Little Creek watershed, within California State Polytechnic Universityâs Swanton Pacific Ranch, is the location of a paired and nested watershed study to investigate the watershed effects of coast redwood forest management. Streamflow, suspended sediment, and stream turbidity have been collected during storms at two locations on the North Fork Little Creek and at...
Elastic versus acoustic inversion for marine surveys
Mora, Peter; Wu, Zedong
2018-04-01
Full Wavefield Inversion (FWI) is a powerful and elegant approach for seismic imaging that is on the way to becoming the method of choice when processing exploration or global seismic data. In the case of processing marine survey data, one may be tempted to assume acoustic FWI is sufficient given that only pressure waves exist in the water layer. In this paper, we pose the question as to whether or not in theory - at least for a hard water bottom case - it should be possible to resolve the shear modulus or S-wave velocity in a marine setting using large offset data. We therefore conduct numerical experiments with idealized marine data calculated with the elastic wave equation. We study two cases, FWI of data due to a diffractor model, and FWI of data due to a fault model. We find that at least in idealized situation, elastic FWI of hard waterbottom data is capable of resolving between the two Lamé parameters λ and μ. Another numerical experiment with a soft waterbottom layer gives the same result. In contrast, acoustic FWI of the synthetic elastic data results in a single image of the first Lamé parameter λ which contains severe artefacts for diffraction data and noticable artefacts for layer reflection data. Based on these results, it would appear that at least, inversions of large offset marine data should be fully elastic rather than acoustic unless it has been demonstrated that for the specific case in question (offsets, model and water depth, practical issues such as soft sediment attenuation of shear waves or computational time), that an acoustic only inversion provides a reasonably good quality of image comparable to that of an elastic inversion. Further research with real data is required to determine the degree to which practical issues such as shear wave attenuation in soft sediments may affect this result.
Elastic versus acoustic inversion for marine surveys
Mora, Peter
2018-04-24
Full Wavefield Inversion (FWI) is a powerful and elegant approach for seismic imaging that is on the way to becoming the method of choice when processing exploration or global seismic data. In the case of processing marine survey data, one may be tempted to assume acoustic FWI is sufficient given that only pressure waves exist in the water layer. In this paper, we pose the question as to whether or not in theory – at least for a hard water bottom case – it should be possible to resolve the shear modulus or S-wave velocity in a marine setting using large offset data. We therefore conduct numerical experiments with idealized marine data calculated with the elastic wave equation. We study two cases, FWI of data due to a diffractor model, and FWI of data due to a fault model. We find that at least in idealized situation, elastic FWI of hard waterbottom data is capable of resolving between the two Lamé parameters λ and μ. Another numerical experiment with a soft waterbottom layer gives the same result. In contrast, acoustic FWI of the synthetic elastic data results in a single image of the first Lamé parameter λ which contains severe artefacts for diffraction data and noticable artefacts for layer reflection data. Based on these results, it would appear that at least, inversions of large offset marine data should be fully elastic rather than acoustic unless it has been demonstrated that for the specific case in question (offsets, model and water depth, practical issues such as soft sediment attenuation of shear waves or computational time), that an acoustic only inversion provides a reasonably good quality of image comparable to that of an elastic inversion. Further research with real data is required to determine the degree to which practical issues such as shear wave attenuation in soft sediments may affect this result.
Elastic Rock Heterogeneity Controls Brittle Rock Failure during Hydraulic Fracturing
Langenbruch, C.; Shapiro, S. A.
2014-12-01
For interpretation and inversion of microseismic data it is important to understand, which properties of the reservoir rock control the occurrence probability of brittle rock failure and associated seismicity during hydraulic stimulation. This is especially important, when inverting for key properties like permeability and fracture conductivity. Although it became accepted that seismic events are triggered by fluid flow and the resulting perturbation of the stress field in the reservoir rock, the magnitude of stress perturbations, capable of triggering failure in rocks, can be highly variable. The controlling physical mechanism of this variability is still under discussion. We compare the occurrence of microseismic events at the Cotton Valley gas field to elastic rock heterogeneity, obtained from measurements along the treatment wells. The heterogeneity is characterized by scale invariant fluctuations of elastic properties. We observe that the elastic heterogeneity of the rock formation controls the occurrence of brittle failure. In particular, we find that the density of events is increasing with the Brittleness Index (BI) of the rock, which is defined as a combination of Young's modulus and Poisson's ratio. We evaluate the physical meaning of the BI. By applying geomechanical investigations we characterize the influence of fluctuating elastic properties in rocks on the probability of brittle rock failure. Our analysis is based on the computation of stress fluctuations caused by elastic heterogeneity of rocks. We find that elastic rock heterogeneity causes stress fluctuations of significant magnitude. Moreover, the stress changes necessary to open and reactivate fractures in rocks are strongly related to fluctuations of elastic moduli. Our analysis gives a physical explanation to the observed relation between elastic heterogeneity of the rock formation and the occurrence of brittle failure during hydraulic reservoir stimulations. A crucial factor for understanding
Modeling Pseudo-elastic Behavior of Springback
International Nuclear Information System (INIS)
Xia, Z. Cedric
2005-01-01
One of the principal foundations of mathematical theory of conventional plasticity for rate-independent metals is that there exists a well-defined yield surface in stress space for any material point under deformation. A material point can undergo further plastic deformation if the applied stresses are beyond current yield surface which is generally referred as 'plastic loading'. On the other hand, if the applied stress state falls within or on the yield surface, the metal will deform elastically only and is said to be undergoing 'elastic unloading'. Although it has been always recognized throughout the history of development of plasticity theory that there is indeed inelastic deformation accompanying elastic unloading, which leads to metal's hysteresis behavior, its effects were thought to be negligible and were largely ignored in the mathematical treatment.Recently there have been renewed interests in the study of unloading behavior of sheet metals upon large plastic deformation and its implications on springback prediction. Springback is essentially an elastic recovery process of a formed sheet metal blank when it is released from the forming dies. Its magnitude depends on the stress states and compliances of the deformed sheet metal if no further plastic loading occurs during the relaxation process. Therefore the accurate determination of material compliances during springback and its effective incorporation into simulation software are important aspects for springback calculation. Some of the studies suggest that the unloading curve might deviate from linearity, and suggestions were made that a reduced elastic modulus be used for springback simulation.The aim of this study is NOT to take a position on the debate of whether elastic moduli are changed during sheet metal forming process. Instead we propose an approach of modeling observed psuedoelastic behavior within the context of mathematical theory of plasticity, where elastic moduli are treated to be
Directory of Open Access Journals (Sweden)
Kevin L. O’Hara
2010-08-01
Full Text Available Tanoak (Notholithocarpus densiflorus syn. Lithocarpus densiflorus is one of the most widespread and abundant associates of coast redwood (Sequoia sempervirens, but little is known about the structural relationships between these two species. Knowledge of such relationships is essential for a thorough understanding of the impacts of sudden oak death (caused by the exotic pathogen Phytophthora ramorum, which is currently decimating tanoak populations throughout the redwood range. In this study, we utilized a stratified plot design and a stand reconstruction technique to assess structural impacts, at present and in the future, of this emerging disease. We found that residual trees in diseased plots were more aggregated than trees in unaffected plots, and we predicted that the loss of tanoak will lead to the following short-term changes: greater average diameter, height, height-to-live-crown, and crown length, as well as an increase in average nearest neighbor differences for diameter, height, and crown length. In addition, plots lacking tanoak (living or dead—as compared to plots with tanoak—exhibited greater average diameter and increased nearest neighbor differences with regard to diameter, height, and crown length. We also conducted a preliminary exploration of how sudden oak death-induced structural changes compare with typical old-growth characteristics, and how this disease may affect the structure of old-growth forests.
Elasticity of fluorite at high temperatures
Eke, J.; Tennakoon, S.; Mookherjee, M.
2017-12-01
Fluorite (CaF2) is a simple halide with cubic space group symmetry (Fm-3m) and is often used as an internal pressure calibrant in moderate high-pressure/high-temperature experiments [1]. In order to gain insight into the elastic behavior of fluorite, we have conducted Resonant Ultrasound Spectroscopy (RUS) on a single crystal of fluorite with rectangular parallelepiped geometry. Using single crystal X-ray diffraction, we aligned the edges of the rectangular parallelepiped with [-1 1 1], [-1 1 -2], and [-1 -1 0] crystallographic directions. We conducted the RUS measurements up to 620 K. RUS spectra are influenced by the geometry, density, and the full elastic moduli tensor of the material. In our high-temperature RUS experiments, the geometry and density were constrained using thermal expansion from previous studies [2]. We determined the elasticity by minimizing the difference between observed resonance and calculated Eigen frequency using Rayleigh-Ritz method [3]. We found that at room temperature, the single crystal elastic moduli for fluorite are 170, 49, and 33 GPa for C11, C12, and C44 respectively. At room temperatures, the aggregate bulk modulus (K) is 90 GPa and the shear modulus (G) is 43 GPa. We note that the elastic moduli and sound wave velocities decrease linearly as a function of temperature with dVP /dT and dVS /dT being -9.6 ×10-4 and -5.0 ×10-4 km/s/K respectively. Our high-temperature RUS results are in good agreement with previous studies on fluorite using both Ultrasonic methods and Brillouin scattering [4,5]. Acknowledgement: This study is supported by US NSF awards EAR-1639552 and EAR-1634422. References: [1] Speziale, S., Duffy, T. S. 2002, Phys. Chem. Miner., 29, 465-472; [2] Roberts, R. B., White, G. K., 1986, J. Phys. C: Solid State Phys., 19, 7167-7172. [3] Migliori, A., Maynard, J. D., 2005, Rev. Sci. Instrum., 76, 121301. [4] Catlow, C. R. A., Comins, J. D., Germano, F. A., Harley, R. T., Hayes, W., 1978, J. Phys. C Solid State Phys
Connecting Jacobi elliptic functions with different modulus parameters
Indian Academy of Sciences (India)
found in the literature do not involve any change in the modulus parameter m. For ... Here, the right-hand side contains the sum of two terms with arguments separated ...... able thing is that, it is precisely these sums for which Landen formulas, mentioned above ... ematical sciences (Springer-Verlag, New York, 1989) vol. 80.
Estimate of K-functionals and modulus of smoothness constructed ...
Indian Academy of Sciences (India)
... and -functionals. The main result of the paper is the proof of the equivalence theorem for a -functional and a modulus of smoothness for the Dunkl transform on R d . Author Affiliations. M El Hamma1 R Daher1. Department of Mathematics, Faculty of Sciences Aïn Chock, University of Hassan II, Casablanca, Morocco ...
Effect of bulk modulus on performance of a hydrostatic transmission ...
Indian Academy of Sciences (India)
an induction motor, a fixed or variable displacement motor, and all required ... oped a linear relation between oil bulk modulus and pressure for a HST system. ..... Piotrowska A 2003 The control of the rotational speed of hydraulic engine in ...
Binding Energy and Compression Modulus of Infinite Nuclear Matter ...
African Journals Online (AJOL)
... MeV at the normal nuclear matter saturation density consistent with the best available density-dependent potentials derived from the G-matrix approach. The results of the incompressibility modulus, k∞ is in excellent agreement with the results of other workers. Journal of the Nigerian Association of Mathematical Physics, ...
Modulus of smoothness and theorems concerning approximation on compact groups
Directory of Open Access Journals (Sweden)
H. Vaezi
2003-01-01
Full Text Available We consider the generalized shift operator defined by (Shuf(g=∫Gf(tut−1gdt on a compact group G, and by using this operator, we define spherical modulus of smoothness. So, we prove Stechkin and Jackson-type theorems.
Karanjule, D. B.; Bhamare, S. S.; Rao, T. H.
2018-04-01
Cold drawing is widely used deformation process for seamless tube manufacturing. Springback is one of the major problem faced in tube drawing. Springback is due to the elastic energy stored in the tubes during forming process. It is found that this springback depends upon Young’s modulus of the material. This paper reports mechanical testing of three grades of steels viz. low carbon steel, medium carbon steel and high carbon steel to measure their Young’s modulus and corresponding springback. The results shows that there is 10-20 % variation in the Young’s modulus and inverse proportion between the springback and Young’s modulus. More the percentage of carbon, more the strength, less the value of Young’s modulus and more will springback. The study further leads to identify optimum die semi angle of 15 degree, land width of 10 mm and drawing speed of 8, 6 and 4 m/min for least springback in all the three grades respectively and die semi angle as a most dominant factor causing springback.
Does maltose influence on the elasticity of SOPC membrane?
Energy Technology Data Exchange (ETDEWEB)
Genova, J; Zheliaskova, A; Mitov, M D, E-mail: ulia@issp.bas.b [Institute of Solid State Physics, Bulgarian Academy of Sciences, 72, Tzarigradsko Chaussee Blvd., 1784 Sofia (Bulgaria)
2010-11-01
Thermally induced shape fluctuations of giant quasi-spherical lipid vesicles are used to study the influence of the disaccharide maltose, dissolved in the aqueous solution, on the curvature elasticity k{sub c} of a lipid membrane. The influence of the carbohydrate solute is investigated throughout a considerably wide interval of concentrations. The values of the bending elastic modulus for 200 mM and 400 mM of maltose in the water solution are obtained. The data for k{sub c} in presence of maltose is compared with previously obtained results for this constant for the most popular hydrocarbons: monosaccharides glucose and fructose and disaccharides sucrose and trehalose. It is shown that the presence of maltose, dissolved in the aqueous phase surrounding the membrane does not influence on the bending elasticity with the increase of its concentration in the aqueous solution. Up to our knowledge this is the first sugar that does not show decrease of the bending elastic modulus of the lipid membrane, when present in the water surrounding it in concentration up to 400 mM.
A micromechanics model of the elastic properties of human dentine
Energy Technology Data Exchange (ETDEWEB)
Kinney, J. H. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Balooch, M. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Marshall, G. W. [Univ. of California, San Francisco, CA (United States). Dept. of Restorative Dentistry; Marshall, S. J. [Univ. of California, San Francisco, CA (United States). Dept. of Restorative Dentistry
1999-10-01
A generalized self-consistent model of cylindrical inclusions in a homogeneous and isotropic matrix phase was used to study the effects of tubule orientation on the elastic properties of dentin. Closed form expressions for the five independent elastic constants of dentin were derived in terms of tubule concentration, and the Young's moduli and Poisson ratios of peri- and intertubular dentin. An atomic force microscope (AFM) indentation technique determined the Young's moduli of the peri- and intertubular dentin as approximately 30 GPa and 15 GPa, respectively. Over the natural variation in tubule density found in dentin, there was only a slight variation in the axial and transverse shear moduli with position in the tooth, and there was no measurable effect of tubule orientation. We conclude that tubule orientation has no appreciable effect on the elastic behavior of normal dentin, and that the elastic properties of healthy dentin can be modeled as an isotropic continuum with a Young's modulus of approximately 16 GPa and a shear modulus of 6.2 GPa.
Insufficiency of the Young’s modulus for illustrating the mechanical behavior of GaN nanowires
Zamani Kouhpanji, Mohammad Reza; Behzadirad, Mahmoud; Feezell, Daniel; Busani, Tito
2018-05-01
We use a non-classical modified couple stress theory including the acceleration gradients (MCST-AG), to precisely demonstrate the size dependency of the mechanical properties of gallium nitride (GaN) nanowires (NWs). The fundamental elastic constants, Young’s modulus and length scales of the GaN NWs were estimated both experimentally, using a novel experimental technique applied to atomic force microscopy, and theoretically, using atomic simulations. The Young’s modulus, static and the dynamic length scales, calculated with the MCST-AG, were found to be 323 GPa, 13 and 14.5 nm, respectively, for GaN NWs from a few nanometers radii to bulk radii. Analyzing the experimental data using the classical continuum theory shows an improvement in the experimental results by introducing smaller error. Using the length scales determined in MCST-AG, we explain the inconsistency of the Young’s moduli reported in recent literature, and we prove the insufficiency of the Young’s modulus for predicting the mechanical behavior of GaN NWs.
Are rapid changes in brain elasticity possible?
Parker, K. J.
2017-09-01
Elastography of the brain is a topic of clinical and preclinical research, motivated by the potential for viscoelastic measures of the brain to provide sensitive indicators of pathological processes, and to assist in early diagnosis. To date, studies of the normal brain and of those with confirmed neurological disorders have reported a wide range of shear stiffness and shear wave speeds, even within similar categories. A range of factors including the shear wave frequency, and the age of the individual are thought to have a possible influence. However, it may be that short term dynamics within the brain may have an influence on the measured stiffness. This hypothesis is addressed quantitatively using the framework of the microchannel flow model, which derives the tissue stiffness, complex modulus, and shear wave speed as a function of the vascular and fluid network in combination with the elastic matrix that comprise the brain. Transformation rules are applied so that any changes in the fluid channels or the elastic matrix can be mapped to changes in observed elastic properties on a macroscopic scale. The results are preliminary but demonstrate that measureable, time varying changes in brain stiffness are possible simply by accounting for vasodynamic or electrochemical changes in the state of any region of the brain. The value of this preliminary exploration is to identify possible mechanisms and order-of-magnitude changes that may be testable in vivo by specialized protocols.
Energy Technology Data Exchange (ETDEWEB)
Guillem-Martí, J. [Biomaterials, Biomechanics and Tissue Engineering Group, Department of Materials Science and Metallurgy, Technical University of Catalonia (UPC), ETSEIB, Av. Diagonal 647, 08028 Barcelona (Spain); Biomedical Research Networking Centre in Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Campus Río Ebro, Edificio I+D Bloque 5, 1a planta, C/ Poeta Mariano Esquillor s/n, 50018 Zaragoza (Spain); Centre for Research in NanoEngineering (CRNE) – UPC, C/Pascual i Vila 15, 08028 Barcelona (Spain); Herranz-Díez, C. [Biomaterials, Biomechanics and Tissue Engineering Group, Department of Materials Science and Metallurgy, Technical University of Catalonia (UPC), ETSEIB, Av. Diagonal 647, 08028 Barcelona (Spain); Biomedical Research Networking Centre in Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Campus Río Ebro, Edificio I+D Bloque 5, 1a planta, C/ Poeta Mariano Esquillor s/n, 50018 Zaragoza (Spain); Shaffer, J.E. [Fort Wayne Metals Research Products Corporation, 9609 Ardmore Avenue, 46809 Fort Wayne (United States); Gil, F.J. [Biomaterials, Biomechanics and Tissue Engineering Group, Department of Materials Science and Metallurgy, Technical University of Catalonia (UPC), ETSEIB, Av. Diagonal 647, 08028 Barcelona (Spain); Biomedical Research Networking Centre in Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Campus Río Ebro, Edificio I+D Bloque 5, 1a planta, C/ Poeta Mariano Esquillor s/n, 50018 Zaragoza (Spain); Centre for Research in NanoEngineering (CRNE) – UPC, C/Pascual i Vila 15, 08028 Barcelona (Spain); and others
2015-06-11
NiTi alloy is the only practical shape memory alloy (SMA) in biomedical use because of its excellent mechanical stability and functionality. However, it is estimated that between 4.5% and 28.5% of the population are hypersensitive to nickel metal, with a higher prevalence in females. Therefore, developing nickel-free low modulus β-type titanium alloys showing shape memory or super elastic behavior would have a great interest in the biomaterials field. Homogeneous 127 μm diameter Ti25Hf21Nb wires were produced and compared to straight annealed Ti–50.8 at% Ni (Nitinol) and 90% cold-drawn 316L wires. Microstructural changes taking place during the heat treatment of cold-worked Ti25Hf21Nb wires were investigated. Large plastic deformation during wire drawing and subsequent annealing led to nano-crystallization and amorphization which may contribute to the observed superelasticity. Mechanical properties were characterized using cyclic uniaxial tension and rotary beam fatigue test modes. A modulus of elasticity of less than 60 GPa and axial recoverable strain of greater than 3% were observed with stress hysteresis resembling a reversible stress-induced martensitic transformation at higher temperatures. The new Ti25Hf21Nb alloy is an important candidate for developing Ni-free SMAs in the future.
International Nuclear Information System (INIS)
Guillem-Martí, J.; Herranz-Díez, C.; Shaffer, J.E.; Gil, F.J.
2015-01-01
NiTi alloy is the only practical shape memory alloy (SMA) in biomedical use because of its excellent mechanical stability and functionality. However, it is estimated that between 4.5% and 28.5% of the population are hypersensitive to nickel metal, with a higher prevalence in females. Therefore, developing nickel-free low modulus β-type titanium alloys showing shape memory or super elastic behavior would have a great interest in the biomaterials field. Homogeneous 127 μm diameter Ti25Hf21Nb wires were produced and compared to straight annealed Ti–50.8 at% Ni (Nitinol) and 90% cold-drawn 316L wires. Microstructural changes taking place during the heat treatment of cold-worked Ti25Hf21Nb wires were investigated. Large plastic deformation during wire drawing and subsequent annealing led to nano-crystallization and amorphization which may contribute to the observed superelasticity. Mechanical properties were characterized using cyclic uniaxial tension and rotary beam fatigue test modes. A modulus of elasticity of less than 60 GPa and axial recoverable strain of greater than 3% were observed with stress hysteresis resembling a reversible stress-induced martensitic transformation at higher temperatures. The new Ti25Hf21Nb alloy is an important candidate for developing Ni-free SMAs in the future
Unraveling complex nonlinear elastic behaviors in rocks using dynamic acousto-elasticity
Riviere, J.; Guyer, R.; Renaud, G.; TenCate, J. A.; Johnson, P. A.
2012-12-01
In comparison with standard nonlinear ultrasonic methods like frequency mixing or resonance based measurements that allow one to extract average, bulk variations of modulus and attenuation versus strain level, dynamic acousto-elasticity (DAE) allows to obtain the elastic behavior over the entire dynamic cycle, detailing the full nonlinear behavior under tension and compression, including hysteresis and memory effects. This method consists of exciting a sample in Bulk-mode resonance at strains of 10-7 to 10-5 and simultaneously probing with a sequence of high frequency, low amplitude pulses. Time of flight and amplitudes of these pulses, respectively related to nonlinear elastic and dissipative parameters, can be plotted versus vibration strain level. Despite complex nonlinear signatures obtained for most rocks, it can be shown that for low strain amplitude (Pasqualini et al., JGR 2007), but not with the extreme detail of elasticity provided by DAE. Previous quasi-static measurements made in Berea sandstone (Claytor et al, GRL 2009), show that the hysteretic behavior disappears when the protocol is performed at a very low strain-rate (static limit). Therefore, future work will aim at linking quasi-static and dynamic observations, i.e. the frequency or strain-rate dependence, in order to understand underlying physical phenomena.
Effects of size and defects on the elasticity of silicon nanocantilevers
Sadeghian, H.; Yang, C.K.; Goosen, J.F.L.; Bossche, A.; Staufer, U.; French, P.J.; Van Keulen, F.
2010-01-01
The size-dependent elastic behavior of silicon nanocantilevers and nanowires, specifically the effective Young’s modulus, has been determined by experimental measurements and theoretical investigations. The size dependence becomes more significant as the devices scale down from micro- to
Elastic and optical properties of Ge x Se 2 Sb 1
Indian Academy of Sciences (India)
... E g ) were investigated with high accuracy. The optically determined bulk modulus of these glasses was in good agreement with that elastically investigated. The obtained results were discussed in terms of the changes in the glass density, electronegativity and electronic polarizability with the variation in antimony content.
International Nuclear Information System (INIS)
Hao Xianfeng; Wu Zhijian; Xu Yuanhui; Zhou Defeng; Liu Xiaojuan; Meng Jian
2007-01-01
We investigate the cohesive energy, heat of formation, elastic constant and electronic band structure of transition metal diborides TMB 2 (TM = Hf, Ta, W, Re, Os and Ir, Pt) in the Pmmn space group using the ab initio pseudopotential total energy method. Our calculations indicate that there is a relationship between elastic constant and valence electron concentration (VEC): the bulk modulus and shear modulus achieve their maximum when the VEC is in the range of 6.8-7.2. In addition, trends in the elastic constant are well explained in terms of electronic band structure analysis, e.g., occupation of valence electrons in states near the Fermi level, which determines the cohesive energy and elastic properties. The maximum in bulk modulus and shear modulus is attributed to the nearly complete filling of TM d-B p bonding states without filling the antibonding states. On the basis of the observed relationship, we predict that alloying W and Re in the orthorhombic structure OsB 2 might be harder than alloying the Ir element. Indeed, the further calculations confirmed this expectation
Energy Technology Data Exchange (ETDEWEB)
Hao Xianfeng [Key Laboratory of Rare Earth Chemistry and Physics, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China); Wu Zhijian [Key Laboratory of Rare Earth Chemistry and Physics, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China); Xu Yuanhui [School of Biological Engineering, Changchun University of Technology, Changchun 130012 (China); Zhou Defeng [School of Biological Engineering, Changchun University of Technology, Changchun 130012 (China); Liu Xiaojuan [Key Laboratory of Rare Earth Chemistry and Physics, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China); Meng Jian [Key Laboratory of Rare Earth Chemistry and Physics, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China)
2007-05-16
We investigate the cohesive energy, heat of formation, elastic constant and electronic band structure of transition metal diborides TMB{sub 2} (TM = Hf, Ta, W, Re, Os and Ir, Pt) in the Pmmn space group using the ab initio pseudopotential total energy method. Our calculations indicate that there is a relationship between elastic constant and valence electron concentration (VEC): the bulk modulus and shear modulus achieve their maximum when the VEC is in the range of 6.8-7.2. In addition, trends in the elastic constant are well explained in terms of electronic band structure analysis, e.g., occupation of valence electrons in states near the Fermi level, which determines the cohesive energy and elastic properties. The maximum in bulk modulus and shear modulus is attributed to the nearly complete filling of TM d-B p bonding states without filling the antibonding states. On the basis of the observed relationship, we predict that alloying W and Re in the orthorhombic structure OsB{sub 2} might be harder than alloying the Ir element. Indeed, the further calculations confirmed this expectation.
Paro, Alberto
2015-01-01
If you are a developer who implements ElasticSearch in your web applications and want to sharpen your understanding of the core elements and applications, this is the book for you. It is assumed that you've got working knowledge of JSON and, if you want to extend ElasticSearch, of Java and related technologies.
Hardrock Elastic Physical Properties: Birch's Seismic Parameter Revisited
Wu, M.; Milkereit, B.
2014-12-01
Identifying rock composition and properties is imperative in a variety of fields including geotechnical engineering, mining, and petroleum exploration, in order to accurately make any petrophysical calculations. Density is, in particular, an important parameter that allows us to differentiate between lithologies and estimate or calculate other petrophysical properties. It is well established that compressional and shear wave velocities of common crystalline rocks increase with increasing densities (i.e. the Birch and Nafe-Drake relationships). Conventional empirical relations do not take into account S-wave velocity. Physical properties of Fe-oxides and massive sulfides, however, differ significantly from the empirical velocity-density relationships. Currently, acquiring in-situ density data is challenging and problematic, and therefore, developing an approximation for density based on seismic wave velocity and elastic moduli would be beneficial. With the goal of finding other possible or better relationships between density and the elastic moduli, a database of density, P-wave velocity, S-wave velocity, bulk modulus, shear modulus, Young's modulus, and Poisson's ratio was compiled based on a multitude of lab samples. The database is comprised of isotropic, non-porous metamorphic rock. Multi-parameter cross plots of the various elastic parameters have been analyzed in order to find a suitable parameter combination that reduces high density outliers. As expected, the P-wave velocity to S-wave velocity ratios show no correlation with density. However, Birch's seismic parameter, along with the bulk modulus, shows promise in providing a link between observed compressional and shear wave velocities and rock densities, including massive sulfides and Fe-oxides.
Effect of alloying on elastic properties of ZrN based transition metal nitride alloys
Kanoun, Mohammed; Goumri-Said, Souraya
2014-01-01
We report the effect of composition and metal sublattice substitutional element on the structural, elastic and electronic properties of ternary transition metal nitrides Zr1-xMxN with M=Al, Ti, Hf, V, Nb, W and Mo. The analysis of the elastic constants, bulk modulus, shear modulus, Young's modulus, and Poisson's ratio provides insights regarding the mechanical behavior of Zr1-xMxN. We predict that ternary alloys are more ductile compared to their parent binary compounds. The revealed trend in the mechanical behavior might help for experimentalists on the ability of tuning the mechanical properties during the alloying process by varying the concentration of the transition metal. © 2014 Elsevier B.V.
Effect of alloying on elastic properties of ZrN based transition metal nitride alloys
Kanoun, Mohammed
2014-09-01
We report the effect of composition and metal sublattice substitutional element on the structural, elastic and electronic properties of ternary transition metal nitrides Zr1-xMxN with M=Al, Ti, Hf, V, Nb, W and Mo. The analysis of the elastic constants, bulk modulus, shear modulus, Young\\'s modulus, and Poisson\\'s ratio provides insights regarding the mechanical behavior of Zr1-xMxN. We predict that ternary alloys are more ductile compared to their parent binary compounds. The revealed trend in the mechanical behavior might help for experimentalists on the ability of tuning the mechanical properties during the alloying process by varying the concentration of the transition metal. © 2014 Elsevier B.V.
Elasticity theory and applications
Saada, Adel S; Hartnett, James P; Hughes, William F
2013-01-01
Elasticity: Theory and Applications reviews the theory and applications of elasticity. The book is divided into three parts. The first part is concerned with the kinematics of continuous media; the second part focuses on the analysis of stress; and the third part considers the theory of elasticity and its applications to engineering problems. This book consists of 18 chapters; the first of which deals with the kinematics of continuous media. The basic definitions and the operations of matrix algebra are presented in the next chapter, followed by a discussion on the linear transformation of points. The study of finite and linear strains gradually introduces the reader to the tensor concept. Orthogonal curvilinear coordinates are examined in detail, along with the similarities between stress and strain. The chapters that follow cover torsion; the three-dimensional theory of linear elasticity and the requirements for the solution of elasticity problems; the method of potentials; and topics related to cylinders, ...
Energy Technology Data Exchange (ETDEWEB)
Ahmed, H. S. Tanvir; Jankowski, Alan F. [Department of Mechanical Engineering, Texas Tech University, Box 41021, Lubbock, Texas 79409 (United States)
2015-03-28
The features of grain size and interface separation strengthen the mechanical behavior of metallic nanolaminates. In addition, the presence of interlayer lattice strains can lead to a superlattice structure within the nanolaminate. The superlattice affects intrinsic properties of technological interest including electronic, magnetic, and elastic. The complex elastic and plastic behaviors of gold–nickel nanolaminate superlattice coatings as studied using nanoindentation are revisited with the tapping mode of a force microscope. Young's modulus is determined with nanoindentation during the initial elastic unloading after plastic deformation at depths up to one-fifth the coating thickness. The tapping mode provides a measurement during the initial elastic deformation at depths of only a few nanometers. The tapping mode utilizes the shift in the resonant frequency of the probe-cantilever system as contact is made with the sample surface. Both of these nanoprobe test methods produce results for measurements conducted with loading normal to the surface plane. A softening in the Young's modulus of gold–nickel nanolaminate coatings occurs for samples with layer pair spacing between 1 and 9 nm. The magnitude of softening corresponds with a progressive increase in the tensile state as measured with the change of interplanar spacing along the growth direction.
Diffraction plane dependency of elastic constants in ferritic steel in neutron stress measurement
International Nuclear Information System (INIS)
Hayashi, M.; Ishiwata, M.; Minakawa, N.; Funahashi, S.
1993-01-01
Neutron diffraction measurements have been made to investigate the elastic properties of the ferritic steel obtained from socket weld. The Kroner elastic model is found to account for the [hkl]-dependence of Young's modulus and Poisson's ratio in the material. Maps of residual stress are later to be made by measuring lattice strain from shifts in the (112) diffraction peak, for which the diffraction elastic constants the herein found to be E=243±5GPa and ν=0.28±0.01. (author)
Elastic constants of a Laves phase compound: C15 NbCr{sub 2}
Energy Technology Data Exchange (ETDEWEB)
Ormeci, A. [Koc Univ., Istanbul (Turkey)]|[Los Alamos National Lab., NM (United States); Chu, F.; Wills, J.M.; Chen, S.P.; Albers, R.C.; Thoma, D.J.; Mitchell, T.E. [Los Alamos National Lab., NM (United States)
1997-04-01
The single-crystal elastic constants of C15 NbCr{sub 2} have been computed by using a first-principles, self-consistent, full-potential total energy method. From these single-crystal elastic constants the isotropic elastic moduli are calculated using the Voigt and Reuss averages. The calculated values are in fair agreement with the experimental values. The implications of the results are discussed with regards to Poisson`s ratio and the direction dependence of Young`s modulus.
International Nuclear Information System (INIS)
Niranjan, Manish K
2015-01-01
We present a comparative study of the anisotropy in the elastic properties of the C49, C54 and C40 phases of TiSi 2 , as well as orthorhombic TiSi and hexagonal Ti 5 Si 3 . The elastic constants, elastic moduli, Debye temperature and sound velocities are computed within the framework of density functional theory. The computed values of the elastic constants and moduli are found to be in excellent agreement with available experimental values. The average elastic moduli, such as Young’s modulus, shear modulus, bulk modulus and Poisson’s ratio, of polycrystalline aggregates are computed using the computed elastic constants of single crystals. The anisotropy in elastic properties is analyzed using estimates of shear anisotropic factors, bulk modulus anisotropic factors and variations in Young’s and bulk moduli in different crystallographic directions. Among the Ti–Si phases, the computed directional Young’s modulus profiles of C49 TiSi 2 and C40 TiSi 2 are found to be quite similar to those of bulk Si and Ti, respectively. In addition to the elastic properties, the electronic structure of five Ti–Si phases is studied. The density of states and planar charge density profiles reveal mixed covalent–metallic bonding in all Ti–Si phases. (paper)
A superplastic Al-Li-Cu-Mg-Zr powder alloy with high hardness and modulus
International Nuclear Information System (INIS)
Phillips, V.A.
1986-01-01
Structure/property studies were made on an experimental Al-3.18% Li-4.29% Cu-1.17% Mg-0.18% Zr powder alloy, which is of the low density/high modulus type. Alloy powder was made by the P and W/GPD rapid solidification rate (RSR) process, canned, and extruded to bar. The density was 2.458 x 10/sup 6/ g/m/sup 3/. The material was solution-treated, and aged at 149 0 C(300 0 F), 171 0 C(340 0 F), and 193 0 C(380 0 F), using hardness tests to determine the aging curves. Testpieces solution-treated at 516 0 C(961 0 F) showed an average yield strength (0.2% offset) of 43.3 ksi (299 MPa) and ultimate tensile strength of 50.0 ksi (345 MPa), with 1% elongation, which increased to 73.0 ksi (503 MPa) and 73.1 ksi (504 MPa), respectively, with only 0.2% elongation, on peak aging at 193 0 C(380 0 F), with a modulus of elasticity of 11.4 x 10/sup 6/ psi (78.3 GPa). Hardness values reached 90-92 R/sub B/ on aging at 149-193 0 C(300-380 0 F). The as-extruded alloy showed superplastic behavior at 400-500 0 C(752-932 0 F) with elongations of 80-185% on 25.6 mm, peaking at 450 0 C(842 0 F). An RSR Al-2.53% Li-2.82% Mn-0.02% Zr extruded allow showed only 18-23% elongation at 400-500 0 C(752-932 0 F)
Bhatia, K. G.; Vyas, S. M.; Patel, A. B.; Bhatt, N. K.; Vyas, P. R.; Gohel, V. B.
2018-05-01
Using parameter-free (first principles local) pseudopotential, in the present communication we have calculated dynamical elastic constants (C11, C12 and C44), bulk modulus (B), shear modulus (µp), Young's modulus (Y) and Poisson's ratio (σ) in long wavelength limit. Our computed results are well agreed for C44 and B with experiment and with other theoretical results obtained within framework of second order perturbation pseudopotential theory. From the present study we conclude that pseudopotential used contain s-p hybridization and no extra term is required to account core-core repulsion.
Elastic properties of Pd40Cu30Ni10P20 bulk glass in supercooled liquid region
DEFF Research Database (Denmark)
Nishiyama, N.; Inoue, A.; Jiang, Jianzhong
2001-01-01
In situ ultrasonic measurements for the Pd40Cu30Ni10P20 bulk glass in three states: Glassy solid, supercooled liquid, and crystalline, have been performed. It is found that velocities of both longitudinal and transverse waves and elastic moduli (shear modulus, bulk modulus, Young's modulus......, and Lame parameter), together with Debye temperature, gradually decrease with increasing temperature through the glass transition temperature as the Poisson's ratio increases. The behavior of the velocity of transverse wave vs. temperature in the supercooled liquid region could be explained by viscosity...
Wingate, Kathryn; Bonani, Walter; Tan, Yan; Bryant, Stephanie J.; Tan, Wei
2012-01-01
The importance of mesenchymal stem cell (MSC) in vascular regeneration is becoming increasingly recognized. However, few in vitro studies have been performed to identify the effects of environmental elasticity on the differentiation of MSC into vascular cell types. We utilized electrospinning and photopolymerization techniques to fabricate a 3D PEGdma nanofiber hydrogel matrix with a tunable elasticity for use as a cellular substrate. Compression testing demonstrated that the elastic modulus ...
Modulus stabilization in a non-flat warped braneworld scenario
Energy Technology Data Exchange (ETDEWEB)
Banerjee, Indrani [S.N. Bose National Centre for Basic Sciences, Department of Astrophysics and Cosmology, Kolkata (India); SenGupta, Soumitra [Indian Association for the Cultivation of Science, Department of Theoretical Physics, Kolkata (India)
2017-05-15
The stability of the modular field in a warped brane world scenario has been a subject of interest for a long time. Goldberger and Wise (GW) proposed a mechanism to achieve this by invoking a massive scalar field in the bulk space-time neglecting the back-reaction. In this work, we examine the possibility of stabilizing the modulus without bringing about any external scalar field. We show that instead of flat 3-branes as considered in Randall-Sundrum (RS) warped braneworld model, if one considers a more generalized version of warped geometry with de Sitter 3-brane, then the brane vacuum energy automatically leads to a modulus potential with a metastable minimum. Our result further reveals that in this scenario the gauge hierarchy problem can also be resolved for an appropriate choice of the brane's cosmological constant. (orig.)
Young's Modulus of Single-Crystal Fullerene C Nanotubes
Directory of Open Access Journals (Sweden)
Tokushi Kizuka
2012-01-01
Full Text Available We performed bending tests on single-crystal nanotubes composed of fullerene C70 molecules by in situ transmission electron microscopy with measurements of loading forces by an optical deflection method. The nanotubes with the outer diameters of 270–470 nm were bent using simple-beam and cantilever-beam loading by the piezomanipulation of silicon nanotips. Young's modulus of the nanotubes increased from 61 GPa to 110 GPa as the outer diameter decreased from 470 nm to 270 nm. Young's modulus was estimated to be 66% of that of single-crystal C60 nanotubes of the same outer diameter.
Mechanical Researches on Young's Modulus of SCS Nanostructures
Directory of Open Access Journals (Sweden)
Qinhua Jin
2009-01-01
Full Text Available Nanostructures of SingleCrystalSilicon (SCS with superior electrical, mechanical, thermal, and optical properties are emerging in the development of novel nanodevices. Mechanical properties especially Young's modulus are essential in developing and utilizing such nanodevices. In this paper, experimental researches including bending tests, resonance tests, and tensile tests on Young' s modulus of nanoscaled SCS are reviewed, and their results are compared. It was found that the values of E measured by different testing methods cannot match to each other. As the differences cannot be explained as experimental errors, it should be understood by taking surface effect into account. With a simplified model, we qualitatively explained the difference in E value measured by tensile test and by resonance test for Si nanobeams.
Effect of uncertainty parameters on graphene sheets Young's modulus prediction
International Nuclear Information System (INIS)
Sahlaoui, Habib; Sidhom Habib; Guedri, Mohamed
2013-01-01
Software based on molecular structural mechanics approach (MSMA) and using finite element method (FEM) has been developed to predict the Young's modulus of graphene sheets. Obtained results have been compared to results available in the literature and good agreement has been shown when the same values of uncertainty parameters are used. A sensibility of the models to their uncertainty parameters has been investigated using a stochastic finite element method (SFEM). The different values of the used uncertainty parameters, such as molecular mechanics force field constants k_r and k_θ, thickness (t) of a graphene sheet and length ( L_B) of a carbon carbon bonds, have been collected from the literature. Strong sensibilities of 91% to the thickness and of 21% to the stretching force (k_r) have been shown. The results justify the great difference between Young's modulus predicted values of the graphene sheets and their large disagreement with experimental results.
High modulus invert analog glass compositions containing beryllia
Bacon, J. F. (Inventor)
1974-01-01
Glass compositions having a Young's modulus of at least 15 million psi and a specific modulus of at least 110 million inches consisting essentially of, in mols, 10-45% SiO2, 2-15% Li2O, 3-34% BeO, 12-36% of at least one bivalent oxide selected from the group consisting of CaO, ZnO, MgO and CuO, 10-39% of at least one trivalent oxide selected from the group consisting of Al2O3, B2O3, La2O3, Y2O3 and the mixed rare earth oxides, the total number of said bivalent and trivalent oxides being at least three, and up to 10% of a tetravalent oxide selected from the group consisting of ZrO2, TiO2 and CeO2.
Two-Sided Estimates of Thermo-elastic Characteristics of Dispersed Inclusion Composites
Directory of Open Access Journals (Sweden)
V. S. Zarubin
2015-01-01
Full Text Available The composites, dispersion-reinforced with inclusions from high-strength and high-modulus materials are widely used in technology. Nanostructure elements can perform the role of such inclusions as well. Possible applications of such composites in heat-stressed structures under heavy mechanical and thermal influences significantly depend on a complex of thermo-mechanical characteristics including the values of the moduli of elasticity and coefficient of linear thermal expansion. There are different approaches to construction of mathematical models that allow calculating dependences to estimate elastic characteristics of composites. Relation between thermoelastic properties of matrix and inclusions of the composite with its temperature coefficient of linear expansion is studied in less detail. Thus, attention has been insufficient in estimating a degree of reliability and a possible error of derived dependencies.A dual variation formulation of the problem of thermo-elasticity in a non-uniform solids simulating the properties and structure of the composite with dispersed inclusions, makes it possible to define two-sided limits of possible values of the volume elasticity modulus, shear modulus, and coefficient of linear thermal expansion of such composite. These limits allow us to estimate the maximum possible error, if to take a half-sum of the limit values of these parameters as the thermoelastic characteristics of the composite. Implementing this approach to find possible errors, arising when using one or another calculating dependency, improves reliability of predicted thermo-elastic characteristics as applied to existing and promising composites.
Experimental Observation of Two Features Unexpected from the Classical Theories of Rubber Elasticity
Nishi, Kengo; Fujii, Kenta; Chung, Ung-il; Shibayama, Mitsuhiro; Sakai, Takamasa
2017-12-01
Although the elastic modulus of a Gaussian chain network is thought to be successfully described by classical theories of rubber elasticity, such as the affine and phantom models, verification experiments are largely lacking owing to difficulties in precisely controlling of the network structure. We prepared well-defined model polymer networks experimentally, and measured the elastic modulus G for a broad range of polymer concentrations and connectivity probabilities, p . In our experiment, we observed two features that were distinct from those predicted by classical theories. First, we observed the critical behavior G ˜|p -pc|1.95 near the sol-gel transition. This scaling law is different from the prediction of classical theories, but can be explained by analogy between the electric conductivity of resistor networks and the elasticity of polymer networks. Here, pc is the sol-gel transition point. Furthermore, we found that the experimental G -p relations in the region above C* did not follow the affine or phantom theories. Instead, all the G /G0-p curves fell onto a single master curve when G was normalized by the elastic modulus at p =1 , G0. We show that the effective medium approximation for Gaussian chain networks explains this master curve.
Dynamic elastic moduli of rocks under pressure
Energy Technology Data Exchange (ETDEWEB)
Schock, R N [Lawrence Radiation Laboratory, University of California, Livermore, CA (United States)
1970-05-01
Elastic moduli are determined as a function of confining pressure to 10 kb on rocks in which Plowshare shots are to be fired. Numerical simulation codes require accurate information on the mechanical response of the rock medium to various stress levels in order to predict cavity dimensions. The theoretical treatment of small strains in an elastic medium relates the propagation velocity of compressional and shear waves to the elastic moduli. Velocity measurements can provide, as unique code input data, the rigidity modulus, Poisson' ratio and the shear wave velocity, as well as providing checks on independent determinations of the other moduli. Velocities are determined using pulsed electro-mechanical transducers and measuring the time-of-flight in the rock specimen. A resonant frequency of 1 MHz is used to insure that the wavelength exceeds the average grain dimension and is subject to bulk rock properties. Data obtained on a variety of rock types are presented and analyzed. These data are discussed in terms of their relationship to moduli measured by static methods as well as the effect of anisotropy, porosity, and fractures. In general, fractured rocks with incipient cracks show large increases in velocity and moduli in the first 1 to 2 kb of compression as a result of the closing of these voids. After this, the velocities increase much more slowly. Dynamic moduli for these rocks are often 10% higher than corresponding static moduli at low pressure, but this difference decreases as the voids are closed until the moduli agree within experimental error. The discrepancy at low pressure is a result of the elastic energy in the wave pulse being propagated around cracks, with little effect on propagation velocity averaged over the entire specimen. (author)
Dynamic elastic moduli of rocks under pressure
International Nuclear Information System (INIS)
Schock, R.N.
1970-01-01
Elastic moduli are determined as a function of confining pressure to 10 kb on rocks in which Plowshare shots are to be fired. Numerical simulation codes require accurate information on the mechanical response of the rock medium to various stress levels in order to predict cavity dimensions. The theoretical treatment of small strains in an elastic medium relates the propagation velocity of compressional and shear waves to the elastic moduli. Velocity measurements can provide, as unique code input data, the rigidity modulus, Poisson' ratio and the shear wave velocity, as well as providing checks on independent determinations of the other moduli. Velocities are determined using pulsed electro-mechanical transducers and measuring the time-of-flight in the rock specimen. A resonant frequency of 1 MHz is used to insure that the wavelength exceeds the average grain dimension and is subject to bulk rock properties. Data obtained on a variety of rock types are presented and analyzed. These data are discussed in terms of their relationship to moduli measured by static methods as well as the effect of anisotropy, porosity, and fractures. In general, fractured rocks with incipient cracks show large increases in velocity and moduli in the first 1 to 2 kb of compression as a result of the closing of these voids. After this, the velocities increase much more slowly. Dynamic moduli for these rocks are often 10% higher than corresponding static moduli at low pressure, but this difference decreases as the voids are closed until the moduli agree within experimental error. The discrepancy at low pressure is a result of the elastic energy in the wave pulse being propagated around cracks, with little effect on propagation velocity averaged over the entire specimen. (author)
Charged string solutions with dilaton and modulus fields
Cvetic, M
1994-01-01
We find charged, abelian, spherically symmetric solutions (in flat space-time) corresponding to the effective action of $D=4$ heterotic string theory with scale-dependent dilaton $\\p$ and modulus $\\vp$ fields. We take into account perturbative (genus-one), moduli-dependent `threshold' corrections to the coupling function $f(\\p,\\vp)$ in the gauge field kinetic term $f(\\p,\\vp) F^2_{\\m\
Determination of dynamic Young’s modulus of vulnerable speleothems
Czech Academy of Sciences Publication Activity Database
Konečný, Pavel; Lednická, Markéta; Souček, Kamil; Staš, Lubomír; Kubina, Lukáš; Gribovszki, K.
2015-01-01
Roč. 20, č. 2 (2015), s. 156-163 ISSN 1335-1788 R&D Projects: GA MŠk ED2.1.00/03.0082; GA MŠk(CZ) LO1406 Institutional support: RVO:68145535 Keywords : dynamic Young´s modulus * speleothem * bulk density * X-Ray Computed Tomography Subject RIV: DB - Geology ; Mineralogy Impact factor: 0.390, year: 2015 http://actamont.tuke.sk/pdf/2015/n2/10Konecny.pdf
A maximum modulus theorem for the Oseen problem
Czech Academy of Sciences Publication Activity Database
Kračmar, S.; Medková, Dagmar; Nečasová, Šárka; Varnhorn, W.
2013-01-01
Roč. 192, č. 6 (2013), s. 1059-1076 ISSN 0373-3114 R&D Projects: GA ČR(CZ) GAP201/11/1304; GA MŠk LC06052 Institutional research plan: CEZ:AV0Z10190503 Keywords : Oseen problem * maximum modulus theorem * Oseen potentials Subject RIV: BA - General Mathematics Impact factor: 0.909, year: 2013 http://link.springer.com/article/10.1007%2Fs10231-012-0258-x
Using data logging to measure Young’s modulus
Richardson, David
2018-03-01
Historically the Young’s modulus of a material is measured by increasing the applied force to a wire and measuring the extension. The cross sectional area and original length allow this to be plotted as a graph of stress versus strain. This article describes how data logging sensors can be used to measure how the force changes with extension, allowing a strain versus stress graph to be plotted into the region of plastic deformation.
Effective stress law for anisotropic elastic deformation
International Nuclear Information System (INIS)
Carroll, M.M.
1979-01-01
An effective stress law is derived analytically to describe the effect of pore fluid pressure on the linearly elastic response of saturated porous rocks which exhibit anisotropy. For general anisotropy the difference between the effective stress and the applied stress is not hydrostatic. The effective stress law involves two constants for transversely isotropic response and three constants for orthotropic response; these constants can be expressed in terms of the moduli of the porous material and of the solid material. These expressions simplify considerably when the anisotropy is structural rather than intrinsic, i.e., in the case of an isotropic solid material with an anisotropic pore structure. In this case the effective stress law involves the solid or grain bulk modulus and two or three moduli of the porous material, for transverse isotropy and orthotropy, respectively. The law reduces, in the case of isotropic response, to that suggested by Geertsma (1957) and by Skempton (1961) and derived analytically by Nur and Byerlee
Elastic buckling of ellipsoids of revolution
International Nuclear Information System (INIS)
Solal, Roger; Hoffmann, Alain; Roche, Roland.
1976-02-01
The CEASEMT system of calculation by finite elements is used to determine critical internal pressures on a flattened ellipsoid of revolution. This case resembles that of an ellipsoidal head of a thin pressure vessel fitted onto a flexible colla. The calculations are performed assuming the geometry perfect, the deformations slight and the behaviour of the material perfectly elastic. The results obtained are presented favourably by plotting a reduced pressure p* against the geometry. A good definition of p* would be: p*=pπ 2 E/1-μ 2 .e 2 b 2 /a 4 (p* critical pressure, E Young's modulus, μ Poisson's coefficient, e thickness, a half large axis, b half small axis). When a/b is above 2 the p value remains close to 1. For lower a/b values the p value rises considerably with a/b [fr
Ultrasonic study of elastic creep in piezoceramics.
Tsaplev, V M; Konovalov, R S
2017-11-01
Ultrasonic method and experimental setup for study the elastic creep of piezoelectric materials are described. The results of experimental studies of time behavior of the Young's modulus and the internal friction are presented as well as the longitudinal and transversal piezomoduli and the electromechanical coupling factor. Four compositions of piezoelectric ceramics both soft and hard, based on BaTiO 3 and PZT, were compressed for a long time (0÷10 7 s) by significant static loads (0÷120MPa). The possible physical mechanisms that cause the creep are briefly considered. The concept of a spectrum of activation energies of the corresponding processes is introduced. The upper and the lower boundaries of the relaxation times spectrum were measured and corresponding activation energies were found. Copyright © 2017 Elsevier B.V. All rights reserved.
Structural and elastic properties of AIBIIIC 2 VI semiconductors
Kumar, V.; Singh, Bhanu P.
2018-01-01
The plane wave pseudo-potential method within density functional theory has been used to calculate the structural and elastic properties of AIBIIIC 2 VI semiconductors. The electronic band structure, density of states, lattice constants (a and c), internal parameter (u), tetragonal distortion (η), energy gap (Eg), and bond lengths of the A-C (dAC) and B-C (dBC) bonds in AIBIIIC 2 VI semiconductors have been calculated. The values of elastic constants (Cij), bulk modulus (B), shear modulus (G), Young's modulus (Y), Poisson's ratio (υ), Zener anisotropy factor (A), Debye temperature (ϴD) and G/B ratio have also been calculated. The values of all 15 parameters of CuTlS2 and CuTlSe2 compounds, and 8 parameters of 20 compounds of AIBIIIC 2 VI family, except AgInS2 and AgInSe2, have been calculated for the first time. Reasonably good agreement has been obtained between the calculated, reported and available experimental values.
Mechanical Properties and Elastic Constants Due to Damage Accumulation and Amorphization in SiC
International Nuclear Information System (INIS)
Gao, Fei; Weber, William J.
2004-01-01
Damage accumulation due to cascade overlap, which was simulated previously, has been used to study the changes of elastic constants, bulk and elastic moduli as a function of dose. These mechanical properties generally decrease with increasing dose, and the rapid decrease at low-dose level indicates that point defects and small clusters play an important role in the changes of elastic constants rather than topological disorder. The internal strain relaxation has no effect on the elastic constants, C11 and C12, in perfect SiC, but it has a significant influence on all elastic constants calculated in damaged SiC. The elastic constants in the cascade-amorphized (CA) SiC decrease about 19%, 29% and 46% for C11, C12 and C44, respectively. The bulk modulus decrease 23% and the elastic modulus decreases 29%, which is consistent with experimental measurements. The stability of both the perfect SiC and CA-SiC under hydrostatic tension has been also investigated. All mechanical properties in the CA-SiC exhibit behavior similar to that in perfect SiC, but the critical stress at which the CA-SiC becomes structurally unstable is one order of magnitude smaller than that for perfect SiC
The elastic properties of zirconium alloy fuel cladding and pressure tubing materials
International Nuclear Information System (INIS)
Rosinger, H.E.; Northwood, D.O.
1979-01-01
A knowledge of the elastic properties of zirconium alloys is required in the mathematical modelling of cladding and pressure tubing performance. Until recently, little of this type of data was available, particularly at elevated temperatures. The dynamic elastic moduli of zircaloy-2, zircaloy-4, the alloys Zr-1.0 wt%Nb, Zr-2.5 wt%Nb and Marz grade zirconium have therefore been determined over the temperature range 275 to 1000 K. Young's modulus and shear modulus for all the zirconium alloys decrease with temperature and are expressed by empirical relations fitted to the data. The elastic properties are texture dependent and a detailed study has been conducted on the effect of texture on the elastic properties of Zr-1.0 wt% Nb over the temperature range 275 to 775 K. The results are compared with polycrystalline elastic constants computed from single crystal elastic constants, and the effect of texture on the dynamic elastic moduli is discussed in detail. (Auth.)
Estimation of Bulk modulus and microhardness of tetrahedral semiconductors
International Nuclear Information System (INIS)
Gorai, Sanjay Kumar
2012-01-01
A general empirical formula was found for calculating of bulk modulus (B) and microhardness (H) from electronegativity and principal quantum number of II-VI, III-V semiconductors. Constant C1, appearing the in the expression of bulk modulus and constants C2 and C3, appearing in the expression of microhardness and the exponent M have following values respectively The numerical values of C1,C2, C3 and M are respectively 206.6, 8.234, 1.291, -1.10 for II-VI 72.4, 31.87, 7.592, -0.95 for III-V semiconductors. Both electro-negativity and principal quantum number can effectively reflect on the chemical bonding behaviour of constituent atoms in these semiconductors. The calculated values of bulk modulus and microhardness are in good agreement with the reported values in the literature. Present study helps in designing novel semiconductor materials, and to further explore the mechanical properties of these semiconductors.
Size-dependent elastic moduli and vibrational properties of fivefold twinned copper nanowires
Zheng, Y. G.; Zhao, Y. T.; Ye, H. F.; Zhang, H. W.
2014-08-01
Based on atomistic simulations, the elastic moduli and vibration behaviors of fivefold twinned copper nanowires are investigated in this paper. Simulation results show that the elastic (i.e., Young’s and shear) moduli exhibit size dependence due to the surface effect. The effective Young’s modulus is found to decrease slightly whereas the effective shear modulus increases slightly with the increase in the wire radius. Both moduli tend to approach certain values at a larger radius and can be suitably described by core-shell composite structure models. Furthermore, we show by comparing simulation results and continuum predictions that, provided the effective Young’s and shear moduli are used, classic elastic theory can be applied to describe the small-amplitude vibration of fivefold twinned copper nanowires. Moreover, for the transverse vibration, the Timoshenko beam model is more suitable because shear deformation becomes apparent.
Size-dependent elastic moduli and vibrational properties of fivefold twinned copper nanowires
International Nuclear Information System (INIS)
Zheng, Y G; Zhao, Y T; Ye, H F; Zhang, H W
2014-01-01
Based on atomistic simulations, the elastic moduli and vibration behaviors of fivefold twinned copper nanowires are investigated in this paper. Simulation results show that the elastic (i.e., Young’s and shear) moduli exhibit size dependence due to the surface effect. The effective Young’s modulus is found to decrease slightly whereas the effective shear modulus increases slightly with the increase in the wire radius. Both moduli tend to approach certain values at a larger radius and can be suitably described by core-shell composite structure models. Furthermore, we show by comparing simulation results and continuum predictions that, provided the effective Young’s and shear moduli are used, classic elastic theory can be applied to describe the small-amplitude vibration of fivefold twinned copper nanowires. Moreover, for the transverse vibration, the Timoshenko beam model is more suitable because shear deformation becomes apparent. (paper)
Youk, Ji Hyun; Son, Eun Ju; Park, Ah Young; Kim, Jeong-Ah
2014-01-01
To evaluate and compare the performance of shear-wave elastography (SWE) for breast masses using the local shear wave speed (m/sec) vs. Young modulus (kPa). A total of 130 breast lesions in 123 women who underwent SWE before ultrasound- guided core needle biopsy or surgical excision were included. With the region-of-interest placed over the stiffest areas of the lesion on SWE, the quantitative mean, maximum, and standard deviation (SD) of the elasticity values were measured in kPa and m/sec for each lesion. The SD was also measured with the region-of-interest including the whole breast lesion (wSD). The area under the receiver operating characteristic curve (AUC), sensitivity, and specificity of each elasticity value measured in kPa and m/sec were compared. Of the 130 lesions, 49 (37.7%) were malignant and 81 (62.3%) were benign. The AUCs for the mean, maximum, and SD of the elasticity values using kPa and m/sec did not differ significantly: mean, 0.974 vs. 0.974; maximum, 0.960 vs. 0.976; SD, 0.916 vs. 0.916. However, the AUC for wSD showed a significant difference: 0.964 (kPa) vs. 0.960 (m/sec) (P=0.036). There was no significant difference in the sensitivity and specificity of the mean, maximum, and wSD of the elasticity values. However, the specificity of the SD was significantly different between the two different measurements: 95.1% (kPa) vs. 87.7% (m/sec) (P=0.031). The quantitative elasticity values measured in kPa and m/sec on SWE showed good diagnostic performance. The specificity of the SD and AUC of the wSD measured in kPa were significantly higher than those measured in m/sec.
Shear-wave elastography for breast masses: local shear wave speed (m/sec) versus Young modulus (kPa)
Energy Technology Data Exchange (ETDEWEB)
Youk, Ji Hyun; Son, Eun Ju; Park, Ah Young; Kim, Jeong Ah [Dept. of Radiology, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul (Korea, Republic of)
2014-03-15
To evaluate and compare the performance of shear-wave elastography (SWE) for breast masses using the local shear wave speed (m/sec) vs. Young modulus (kPa). A total of 130 breast lesions in 123 women who underwent SWE before ultrasound- guided core needle biopsy or surgical excision were included. With the region-of-interest placed over the stiffest areas of the lesion on SWE, the quantitative mean, maximum, and standard deviation (SD) of the elasticity values were measured in kPa and m/sec for each lesion. The SD was also measured with the region-of-interest including the whole breast lesion (wSD). The area under the receiver operating characteristic curve (AUC), sensitivity, and specificity of each elasticity value measured in kPa and m/sec were compared. Of the 130 lesions, 49 (37.7%) were malignant and 81 (62.3%) were benign. The AUCs for the mean, maximum, and SD of the elasticity values using kPa and m/sec did not differ significantly: mean, 0.974 vs. 0.974; maximum, 0.960 vs. 0.976; SD, 0.916 vs. 0.916. However, the AUC for wSD showed a significant difference: 0.964 (kPa) vs. 0.960 (m/sec) (P=0.036). There was no significant difference in the sensitivity and specificity of the mean, maximum, and wSD of the elasticity values. However, the specificity of the SD was significantly different between the two different measurements: 95.1% (kPa) vs. 87.7% (m/sec) (P=0.031). The quantitative elasticity values measured in kPa and m/sec on SWE showed good diagnostic performance. The specificity of the SD and AUC of the wSD measured in kPa were significantly higher than those measured in m/sec.
Shear-wave elastography for breast masses: local shear wave speed (m/sec) versus Young modulus (kPa)
International Nuclear Information System (INIS)
Youk, Ji Hyun; Son, Eun Ju; Park, Ah Young; Kim, Jeong Ah
2014-01-01
To evaluate and compare the performance of shear-wave elastography (SWE) for breast masses using the local shear wave speed (m/sec) vs. Young modulus (kPa). A total of 130 breast lesions in 123 women who underwent SWE before ultrasound- guided core needle biopsy or surgical excision were included. With the region-of-interest placed over the stiffest areas of the lesion on SWE, the quantitative mean, maximum, and standard deviation (SD) of the elasticity values were measured in kPa and m/sec for each lesion. The SD was also measured with the region-of-interest including the whole breast lesion (wSD). The area under the receiver operating characteristic curve (AUC), sensitivity, and specificity of each elasticity value measured in kPa and m/sec were compared. Of the 130 lesions, 49 (37.7%) were malignant and 81 (62.3%) were benign. The AUCs for the mean, maximum, and SD of the elasticity values using kPa and m/sec did not differ significantly: mean, 0.974 vs. 0.974; maximum, 0.960 vs. 0.976; SD, 0.916 vs. 0.916. However, the AUC for wSD showed a significant difference: 0.964 (kPa) vs. 0.960 (m/sec) (P=0.036). There was no significant difference in the sensitivity and specificity of the mean, maximum, and wSD of the elasticity values. However, the specificity of the SD was significantly different between the two different measurements: 95.1% (kPa) vs. 87.7% (m/sec) (P=0.031). The quantitative elasticity values measured in kPa and m/sec on SWE showed good diagnostic performance. The specificity of the SD and AUC of the wSD measured in kPa were significantly higher than those measured in m/sec.
Elastic-plastic transition: A universal law
Directory of Open Access Journals (Sweden)
Chen Zhong
2016-01-01
Full Text Available Although the initial stress-strain behavior in a tensile test is often characterized as linear elastic up to a yield stress and nonlinear plastic thereafter, the pre-yield transition region is known to exhibit significant curvature and hysteresis. Hundreds of high-precision loading-unloading-loading tensile tests were performed using 26 commercial sheet alloys exhibiting a wide range of strength, ductility and crystal structure. Analysis of the results reveals the following: 1.There is no significant linear elastic region; the proportional limit is ~0 MPa when measured with sufficient sensitivity. 2.Each of the hundreds of measured transitional stress-strain curves can be characterized by a single parameter, here called the “modulus reduction rate.”The corresponding equation captures ~80% of the observed variation, a factor of 3 to 6 better than a one-parameter linear approximation. 3.Most interestingly, the transitional behavior for all alloys follows a “Universal Law” requiring no fit parameters. The law depends only upon the strength of the material and its Young’s modulus, both of which are can be measured by independent tests or adopted from handbooks. The Universal Law captures ~90% of the variation represented by the one-parameter representation and eliminates the need for mechanical testing to implement and apply. The practical and theoretical implications of these results are discussed. The results provide a simple path to significantly improving applied constitutive models in the transitional regime. The consistency of the effect for such a wide range of metals and suggests that the origin of the behavior lies in the pile-up and relaxation of dislocation arrays.
Statistical mechanics of elasticity
Weiner, JH
2012-01-01
Advanced, self-contained treatment illustrates general principles and elastic behavior of solids. Topics include thermoelastic behavior of crystalline and polymeric solids, interatomic force laws, behavior of solids, and thermally activated processes. 1983 edition.