Static and dynamic through thickness lamina properties of thick laminates
Lahuerta, F.; Nijssen, R.P.L.; Van der Meer, F.P.; Sluys, L.J.
2015-01-01
Thick laminates are increasingly present in large composites structures such as wind turbine blades. Different factors are suspected to be involved in the decreased static and dynamic performance of thick laminates. These include the effect of self-heating, the scaling effect, and the manufacturing
PENG Fan; FU YiMing; CHEN YaoJun
2008-01-01
The effect of matrix cracking on the bifurcation creep buckling of viscoelastic laminated circular cylindrical shells is investigated. The viscoelastic behavior of laminas is modeled by Schapery's integral constitutive equation with growing ma-trix cracks. The values of damage variables are correlated to non-dimensional density of matrix cracks relying on the formulas from meso-mechanics approach, and the evolution equation predicting the growth rate of density of matrix cracks is assumed to follow a power type relation with transverse tensile stress. The gov-erning equations for pre-buckling creep deformation and bifurcation buckling of laminated circular cylindrical shells under axial compression are obtained on the basis of the Donnell type shallow shell theory and Karman-Donnell geometrically nonlinear relationship. Corresponding solution strategy is constructed by inte-grating finite-difference technique, trigonometric series expansion method and Taylor's numerical recursive scheme for convolution integration. The bifurcation creep buckling of symmetrically laminated glass-epoxy circular cylindrical shells with matrix creep cracking coupled are examined for various geometrical parame-ters and parameters of damage evolution as well as boundary conditions. The nu-merical results show that matrix creep cracking remarkably shortens the critic time of bifurcation buckling and reduces the durable critic loads, and its effects become weak and finally vanish with the increase of the ratio of radius to thickness in the case of short laminated circular cylindrical shells, also the influence of the matrix creep cracking is mainly dependent on the boundary conditions at two ends for moderately long circular cylindrical shells.
2008-01-01
The effect of matrix cracking on the bifurcation creep buckling of viscoelastic laminated circular cylindrical shells is investigated.The viscoelastic behavior of laminas is modeled by Schapery’s integral constitutive equation with growing matrix cracks.The values of damage variables are correlated to non-dimensional density of matrix cracks relying on the formulas from mesomechanics approach,and the evolution equation predicting the growth rate of density of matrix cracks is assumed to follow a power type relation with transverse tensile stress.The governing equations for prebuckling creep deformation and bifurcation buckling of laminated circular cylindrical shells under axial compression are obtained on the basis of the Donnell type shallow shell theory and Kármán-Donnell geometrically nonlinear relationship.Corresponding solution strategy is constructed by integrating finite-difference technique,trigonometric series expansion method and Taylor’s numerical recursive scheme for convolution integration.The bifurcation creep buckling of symmetrically laminated glass-epoxy circular cylindrical shells with matrix creep cracking coupled are examined for various geometrical parameters and parameters of damage evolution as well as boundary conditions.The numerical results show that matrix creep cracking remarkably shortens the critic time of bifurcation buckling and reduces the durable critic loads,and its effects become weak and finally vanish with the increase of the ratio of radius to thickness in the case of short laminated circular cylindrical shells,also the influence of the matrix creep cracking is mainly dependent on the boundary conditions at two ends for moderately long circular cylindrical shells.
Study of laminated anisotropic cylindrical shells sensitive to transverse stresses
Massard, Thierry
1979-01-01
A variational method for the determination of stresses and displacements in a multilayered cylindrical shell is presented. All included materials are linearly anisotropic (monoclinic) - i.e. directional fibres reinforced materials. This study uses a functional which is derived from the potential energy of the structure. The incoming stresses are σ RR , σ Rθ , σ RZ , and the displacements are u θ and u Z . This mixed group is the main variables of the formulation. It is shown that the stationarity conditions of the functional are the equilibrium equations and the associated boundary conditions. An approximate solution can be found using a finite element method which realizes a tridimensional discretization of the structure. The program issued is a specific mean for studying the transverse shear stresses in laminated cylindrical structures. From the results obtained it can be concluded that it meets all requirements for the purposes of this range of problems. (author) [fr
Self-heating forecasting for thick laminate specimens in fatigue
Lahuerta, F.; Westphal, T.; Nijssen, R. P. L.
2014-12-01
Thick laminate sections can be found from the tip to the root in most common wind turbine blade designs. Obtaining accurate and reliable design data for thick laminates is subject of investigations, which include experiments on thick laminate coupons. Due to the poor thermal conductivity properties of composites and the material self-heating that occurs during the fatigue loading, high temperature gradients may appear through the laminate thickness. In the case of thick laminates in high load regimes, the core temperature might influence the mechanical properties, leading to premature failures. In the present work a method to forecast the self-heating of thick laminates in fatigue loading is presented. The mechanical loading is related with the laminate self-heating, via the cyclic strain energy and the energy loss ratio. Based on this internal volumetric heat load a thermal model is built and solved to obtain the temperature distribution in the transient state. Based on experimental measurements of the energy loss factor for 10mm thick coupons, the method is described and the resulting predictions are compared with experimental surface temperature measurements on 10 and 30mm UD thick laminate specimens.
Buckling of pressure-loaded, long, shear deformable, cylindrical laminated shells
Anastasiadis, John S.; Simitses, George J.
A higher-order shell theory was developed (kinematic relations, constitutive relations, equilibrium equations and boundary conditions), which includes initial geometric imperfections and transverse shear effects for a laminated cylindrical shell under the action of pressure, axial compression and in-plane shear. Through the perturbation technique, buckling equations are derived for the corresponding 'perfect geometry' symmetric laminated configuration. Critical pressures are computed for very long cylinders for several stacking sequences, several radius-to-total-thickness ratios, three lamina materials (boron/epoxy, graphite/epoxy, and Kevlar/epoxy), and three shell theories: classical, first-order shear deformable and higher- (third-)order shear deformable. The results provide valuable information concerning the applicability (accurate prediction of buckling pressures) of the various shell theories.
Three-dimensional free vibration analysis of thick laminated circular ...
Dr Oke
1 ,2 Department of Mechanical Engineering, Maulana Azad National Institute of Technology, Bhopal-462003, INDIA ... In this communication, a numerical analysis regarding free vibration of thick laminated .... ANSYS finite element software.
Sørensen, Rene; Lund, Erik
2015-01-01
This paper presents a new gradient based method for performing discrete material and thickness optimization of laminated composite structures. The novelty in the new method lies in the application of so-called casting constraints, or thickness filters in this context, to control the thickness...... variation throughout the laminate. The filters replace the layerwise density variables with a single continuous through-the-thickness design variable. Consequently, the filters eliminate the need for having explicit constraints for preventing intermediate void through the thickness of the laminate....... Therefore, the filters reduce both the number of constraints and design variables in the optimization problem. Based upon a continuous approximation of a unit step function, the thickness filters are capable of projecting discrete 0/1 values to the underlying layerwise or ”physical” density variables which...
Malekzadeh, P.; Heydarpour, Y.; Haghighi, M.R. Golbahar; Vaghefi, M.
2012-01-01
Based on the elasticity theory, the transient analysis of dynamically pressurized rotating multi-layered functionally graded (FG) cylindrical shells in thermal environment is presented. The variations of the field variables across the shell thickness are accurately modeled by dividing the shell into a set of co-axial mathematical layers in the radial direction. The initial thermo-mechanical stresses are obtained by solving the thermoelastic equilibrium equations. The differential quadrature method and Newmark's time integration scheme are employed to discretize the obtained governing equations of each mathematical layer. After performing the convergence and comparison studies, parametric studies for two common types of FG sandwich shells, namely, the shell with homogeneous inner/outer layers and FG core and the shell with FG inner/outer layers and homogeneous core are carried out. The influences of the temperature dependence of material properties, material graded index, the convective heat transfer coefficient, the angular velocity, the boundary condition and the geometrical parameters (length and thickness to outer radius ratios) on the dynamic response of the FG shells are investigated. Highlights: ► As a first endeavor, transient analysis of rotating laminated functionally graded cylinders. ► Employing an elasticity based discrete layer-differential quadrature method. ► Evaluating and including the initial thermo-mechanical stresses accurately. ► Considering the temperature-dependence of the material properties. ► Presenting some new results, which can be used as benchmark solution for future works.
Buckling Optimization of Thick Stiffened Cylindrical Shell
Qasim Hassan Bader
2016-03-01
Full Text Available In this work the critical pressure due to buckling was calculated numerically by using ANSYS15 for both stiffened and un-stiffened cylinder for various locations and installing types , strengthening of the cylinder causes a more significant increase in buckling pressures than non reinforced cylinder . The optimum design of structure was done by using the ASYS15 program; in this step the number of design variables 21 DVs. These variables are Independent variables that directly affect. The design variables represented the thickness of the cylinder and( height and width of 10 stiffeners. State variables (SVs, these variables are dependent variables that change as a result of changing the DVs and are necessary to constrain the design. The objective function is the one variable in the optimization that needs to be minimized. In this case the state variable is critical pressure (CP and the objective function is the total (volume of the structure. The optimum weight of the structure with reasonable required conditions for multi types of structure was found. The result shows the best location of stiffener at internal side with circumferential direction. In this case the critical pressure can be increased about 18.6% and the total weight of the structure decreases to 15.8%.
Curing of Thick Thermoset Composite Laminates: Multiphysics Modeling and Experiments
Anandan, S.; Dhaliwal, G. S.; Huo, Z.; Chandrashekhara, K.; Apetre, N.; Iyyer, N.
2017-11-01
Fiber reinforced polymer composites are used in high-performance aerospace applications as they are resistant to fatigue, corrosion free and possess high specific strength. The mechanical properties of these composite components depend on the degree of cure and residual stresses developed during the curing process. While these parameters are difficult to determine experimentally in large and complex parts, they can be simulated using numerical models in a cost-effective manner. These simulations can be used to develop cure cycles and change processing parameters to obtain high-quality parts. In the current work, a numerical model was built in Comsol MultiPhysics to simulate the cure behavior of a carbon/epoxy prepreg system (IM7/Cycom 5320-1). A thermal spike was observed in thick laminates when the recommended cure cycle was used. The cure cycle was modified to reduce the thermal spike and maintain the degree of cure at the laminate center. A parametric study was performed to evaluate the effect of air flow in the oven, post cure cycles and cure temperatures on the thermal spike and the resultant degree of cure in the laminate.
Analytical and Experimental Characterization of Thick-Section Fiber-Metal Laminates
2013-06-01
laminate . The model individually models each layer of the laminate and predicts stiffness degradation as metal layers plastically deform and as prepreg ...eliminating four of the possible ECM laminates . Additionally, since at least four individual layers (two aluminum and two prepreg ) are used in FML an...AFRL-AFOSR-UK-TR-2013-0023 Analytical and Experimental Characterization of Thick- Section Fiber-Metal Laminates Dr. Rene
Enamel thickness after preparation of tooth for porcelain laminate.
Pahlevan, Ayoub; Mirzaee, Mansoreh; Yassine, Esmaeil; Ranjbar Omrany, Ladan; Hasani Tabatabaee, Masumeh; Kermanshah, Hamid; Arami, Sakineh; Abbasi, Mehdy
2014-07-01
In this investigation the thickness of enamel in the gingival, middle, and incisal thirds of the labial surface of the anterior teeth were measured regarding preparation of the teeth for porcelain laminate veneers. Part one, 20 extracted intact human maxillary central and lateral incisors ten of each were selected. The teeth were imbedded in autopolimerize acrylic resin. Cross section was preformed through the midline of the incisal, middle and cervical one-third of the labial surface of the teeth. The samples were observed under reflected stereomicroscope and the thickness of enamel was recorded. Part II, the effect of different types of preparation on dentin exposure was evaluated. Thirty maxillary central incisor teeth were randomly divided into two groups: A: Knife-edge preparation. B: Chamfer preparation. All samples were embedded in autopolimerize acrylic resin using a silicon mold. The samples were cut through the midline of the teeth. The surface of the samples were polished and enamel and dentin were observed under the stereomicroscope. Data were analyzed by ANOVA-one way test. The results of this study showed that the least enamel thickness in the central incisor was 345 and in lateral incisor is 235 μ this thickness is related to the one-third labial cervical area. Maximum thickness in maxillary central and lateral incisors in the one-third labial incisal surface was 1260 μ and 1220μ, respectively. In the second part of the study, the tendency of dentinal exposure was shown with the chamfer preparation, but no dentinal exposure was found in the knife-edge preparation. The differences between groups were significant (p<0.05). The knowledge of enamel thickness in different part of labial surface is very important. The thickness of enamel in the gingival area does not permit a chamfer preparation. The knife edge preparation is preferable in gingival area.
Enamel thickness after preparation of tooth for porcelain laminate.
Ayoub Pahlevan
2014-08-01
Full Text Available In this investigation the thickness of enamel in the gingival, middle, and incisal thirds of the labial surface of the anterior teeth were measured regarding preparation of the teeth for porcelain laminate veneers.Part one, 20 extracted intact human maxillary central and lateral incisors ten of each were selected. The teeth were imbedded in autopolimerize acrylic resin. Cross section was preformed through the midline of the incisal, middle and cervical one-third of the labial surface of the teeth. The samples were observed under reflected stereomicroscope and the thickness of enamel was recorded. Part II, the effect of different types of preparation on dentin exposure was evaluated. Thirty maxillary central incisor teeth were randomly divided into two groups: A: Knife-edge preparation. B: Chamfer preparation. All samples were embedded in autopolimerize acrylic resin using a silicon mold. The samples were cut through the midline of the teeth. The surface of the samples were polished and enamel and dentin were observed under the stereomicroscope.Data were analyzed by ANOVA-one way test. The results of this study showed that the least enamel thickness in the central incisor was 345 and in lateral incisor is 235 μ this thickness is related to the one-third labial cervical area. Maximum thickness in maxillary central and lateral incisors in the one-third labial incisal surface was 1260 μ and 1220μ, respectively. In the second part of the study, the tendency of dentinal exposure was shown with the chamfer preparation, but no dentinal exposure was found in the knife-edge preparation. The differences between groups were significant (p<0.05.The knowledge of enamel thickness in different part of labial surface is very important. The thickness of enamel in the gingival area does not permit a chamfer preparation. The knife edge preparation is preferable in gingival area.
Malekzadeh, P. [Department of Mechanical Engineering, Persian Gulf University, Boushehr 75168 (Iran, Islamic Republic of); Center of Excellence for Computational Mechanics in Mechanical Engineering, Shiraz University, Shiraz (Iran, Islamic Republic of)], E-mail: malekzadeh@pgu.ac.ir; Farid, M. [Center of Excellence for Computational Mechanics in Mechanical Engineering, Shiraz University, Shiraz (Iran, Islamic Republic of); Department of Mechanical Engineering, Shiraz University, Shiraz (Iran, Islamic Republic of); Zahedinejad, P. [Department of Mechanical Engineering, Shiraz University, Shiraz (Iran, Islamic Republic of)
2008-07-15
A mixed layerwise theory and differential quadrature (DQ) method (LW-DQ) for three-dimensional free vibration analysis of arbitrary laminated circular cylindrical shells is introduced. Using the layerwise theory in conjunction with the three-dimensional form of Hamilton's principle, the transversely discretized equations of motion and the related boundary conditions are obtained. Then, the DQ method is employed to discretize the resulting equations in the axial directions. The fast convergence behavior of the method is demonstrated and its accuracy is verified by comparing the results with those of other shell theories obtained using conventional methods and also with those of ANSYS software. In the case of arbitrary laminated shells with simply supported ends, the exact solution is developed for comparison purposes. It is shown that using few DQ grid points, converged accurate solutions are obtained. Less computational efforts of the proposed approach with respect to ANSYS software is shown.
Nakai Kenji
2015-01-01
Full Text Available The effect of strain rate up to approximately ε̇ = 102/s on the tensile stress–strain properties of unidirectional and cross-ply carbon/epoxy laminated composites in the through-thickness direction is investigated. Waisted cylindrical specimens machined out of the laminated composites in the through-thickness direction are used in both static and dynamic tests. The dynamic tensile stress–strain curves up to fracture are determined using the split Hopkinson bar (SHB. The low and intermediate strain-rate tensile stress–strain relations up to fracture are measured on an Instron 5500R testing machine. It is demonstrated that the ultimate tensile strength and absorbed energy up to fracture increase significantly, while the fracture strain decreases slightly with increasing strain rate. Macro- and micro-scopic examinations reveal a marked difference in the fracture surfaces between the static and dynamic tension specimens.
Free vibration of symmetric angle-ply laminated circular cylindrical shells
Viswanathan, K K; Aziz, Zainal Abdul; Amirah, H Z; Javed, Saira
2014-01-01
Free vibration of symmetric angle-ply laminated circular cylindrical shells is studied using Spline approximation. The equations of motions in longitudinal, circumferential and transverse displacement components, are derived using Love's first approximation theory. The coupled differential equations are solved using Spline approximation to obtain the generalized eigenvalue problem. Parametric studies are performed to analyse the frequency response of the shell with reference to the material properties, number of layers, ply orientation, length and circumferential node number and different boundary conditions
Self-heating forecasting for thick laminates testing coupons in fatigue
Lahuerta, F.; Westphal, T.; Nijssen, R.P.L.
2012-01-01
Thick laminate sections can be found from the tip to the root in most common wind turbine blade designs. Obtaining accurate and reliable design data for thick laminates is subject of investigations. Due to the poor thermal conductivity properties of composites and the material self-heating that
Normalization of Impact Energy by Laminate Thickness for Compression After Impact Testing
Nettles, A. T.; Hromisin, S. M.
2013-01-01
The amount of impact energy used to damage a composite laminate is a critical parameter when assessing residual strength properties. The compression after impact (CAI) strength of impacted laminates is dependent upon how thick the laminate is and this has traditionally been accounted for by normalizing (dividing) the impact energy by the laminate's thickness. However, when comparing CAI strength values for a given lay-up sequence and fiber/resin system, dividing the impact energy by the specimen thickness has been noted by the author to give higher CAI strength values for thicker laminates. A study was thus undertaken to assess the comparability of CAI strength data by normalizing the impact energy by the specimen thickness raised to a power to account for the higher strength of thicker laminates. One set of data from the literature and two generated in this study were analyzed by dividing the impact energy by the specimen thickness to the 1, 1.5, 2, and 2.5 powers. Results show that as laminate thickness and damage severity decreased, the value which the laminate thickness needs to be raised to in order to yield more comparable CAI data increases.
Zhang, W.; Liu, T.; Xi, A.; Wang, Y. N.
2018-06-01
This paper is focused on the resonant responses and chaotic dynamics of a composite laminated circular cylindrical shell with radially pre-stretched membranes at both ends and clamped along a generatrix. Based on the two-degree-of-freedom non-autonomous nonlinear equations of this system, the method of multiple scales is employed to obtain the four-dimensional nonlinear averaged equation. The resonant case considered here is the primary parametric resonance-1/2 subharmonic resonance and 1:1 internal resonance. Corresponding to several selected parameters, the frequency-response curves are obtained. From the numerical results, we find that the hardening-spring-type behaviors and jump phenomena are exhibited. The jump phenomena also occur in the amplitude curves of the temperature parameter excitation. Moreover, it is found that the temperature parameter excitation, the coupling degree of two order modes and the detuning parameters can effect the nonlinear oscillations of this system. The periodic and chaotic motions of the composite laminated circular cylindrical shell clamped along a generatrix are demonstrated by the bifurcation diagrams, the maximum Lyapunov exponents, the phase portraits, the waveforms, the power spectrums and the Poincaré map. The temperature parameter excitation shows that the Pomeau-Manneville type intermittent chaos occur under the certain initial conditions. It is also found that there exist the twin phenomena between the Pomeau-Manneville type intermittent chaos and the period-doubling bifurcation.
Hollow cylindrical plasma filament waveguide with discontinuous finite thickness cladding
Alshershby, Mostafa; Hao Zuoqiang; Lin Jingquan
2013-01-01
We have explored here a hollow cylindrical laser plasma multifilament waveguide with discontinuous finite thickness cladding, in which the separation between individual filaments is in the range of several millimeters and the waveguide cladding thickness is in the order of the microwave penetration depth. Such parameters give a closer representation of a realistic laser filament waveguide sustained by a long stable propagation of femtosecond (fs) laser pulses. We report how the waveguide losses depend on structural parameters like normalized plasma filament spacing, filament to filament distance or pitch, normal spatial frequency, and radius of the plasma filament. We found that for typical plasma parameters, the proposed waveguide can support guided modes of microwaves in extremely high frequency even with a cladding consisting of only one ring of plasma filaments. The loss of the microwave radiation is mainly caused by tunneling through the discontinuous finite cladding, i.e., confinement loss, and is weakly dependent on the plasma absorption. In addition, the analysis indicates that the propagation loss is fairly large compared with the loss of a plasma waveguide with a continuous infinite thickness cladding, while they are comparable when using a cladding contains more than one ring. Compared to free space propagation, this waveguide still presents a superior microwave transmission to some distance in the order of the filamentation length; thus, the laser plasma filaments waveguide may be a potential channel for transporting pulsed-modulated microwaves if ensuring a long and stable propagation of fs laser pulses.
Wave motion in a thick cylindrical rod undergoing longitudinal impact
Červ, Jan; Adámek, V.; Valeš, František; Gabriel, Dušan; Plešek, Jiří
2016-01-01
Roč. 66, November (2016), s. 88-105 ISSN 0165-2125 R&D Projects: GA ČR(CZ) GAP101/12/2315; GA TA ČR(CZ) TH01010772 Institutional support: RVO:61388998 Keywords : elastic waves * impact * thick cylindrical rod * analytical solution * semi-analytical solution Subject RIV: BI - Acoustics Impact factor: 1.575, year: 2016 http://ac.els-cdn.com/S0165212516300427/1-s2.0-S0165212516300427-main.pdf?_tid=d91eee02-7a55-11e6-8c02-00000aab0f6c&acdnat=1473842161_c56543aaec31b7e091ab47d3fb38f361
Vibrations of laminated composite thick shells of revolution having meridionally varying curvature
Suzuki, Katsuyoshi; Shikanai, Genji; Baba, Iwato
1998-01-01
An exact solution is presented for solving free vibrations of laminated composite thick shells of revolution having meridionally varying curvature. Based on the thick lamination theory considering the shear deformation and rotary inertia, equations of motion and boundary conditions are obtained from the stationary conditions of the Lagrangian. The equations of motion are solved exactly by using a power series expansion for symmetrically laminated cross-ply shells. Frequencies and mode shapes of shells of revolution having elliptical and parabolical meridians are presented for both ends clamped, and the effects of shear deformation and rotary inertia are discussed by comparing the results from the present theory with those from the thin lamination theory. (author)
Lovejoy, Andrew Elwyn
1994-01-01
Composite materials are increasingly finding use in structures, such as aircraft components, and thus, an accurate method of predicting response is required. Even laminated structures that are considered thin can be significantly affected by transverse shear effects, and as a result, transverse shear should not be neglected. The free vibration response of generally-laminated, thick, skew, trapezoidal plates is investigated as there appears to be a lack of information in this ar...
Zamani Nejad, Mohammad; Jabbari, Mehdi; Ghannad, Mehdi
2014-01-01
Using disk form multilayers, a semi-analytical solution has been derived for determination of displacements and stresses in a rotating cylindrical shell with variable thickness under uniform pressure. The thick cylinder is divided into disk form layers form with their thickness corresponding to the thickness of the cylinder. Due to the existence of shear stress in the thick cylindrical shell with variable thickness, the equations governing disk layers are obtained based on first-order shear deformation theory (FSDT). These equations are in the form of a set of general differential equations. Given that the cylinder is divided into n disks, n sets of differential equations are obtained. The solution of this set of equations, applying the boundary conditions and continuity conditions between the layers, yields displacements and stresses. A numerical solution using finite element method (FEM) is also presented and good agreement was found.
Mohammad Zamani Nejad
2014-01-01
Full Text Available Using disk form multilayers, a semi-analytical solution has been derived for determination of displacements and stresses in a rotating cylindrical shell with variable thickness under uniform pressure. The thick cylinder is divided into disk form layers form with their thickness corresponding to the thickness of the cylinder. Due to the existence of shear stress in the thick cylindrical shell with variable thickness, the equations governing disk layers are obtained based on first-order shear deformation theory (FSDT. These equations are in the form of a set of general differential equations. Given that the cylinder is divided into n disks, n sets of differential equations are obtained. The solution of this set of equations, applying the boundary conditions and continuity conditions between the layers, yields displacements and stresses. A numerical solution using finite element method (FEM is also presented and good agreement was found.
Lepedat, Karin; Wagner, Robert; Lang, Jürgen
The use of phenolic resin for the impregnation of a carrier material such as paper or fabric based on either organic or inorganic fibers was and still is one of the most important application areas for liquid phenolic resins. Substrates like paper, cotton, or glass fabric impregnated with phenolic resins are used as core layers for decorative and technical laminates and for many other different industrial applications. Nowadays, phenolic resins for decorative laminates used for furniture, flooring, or in the construction and transportation industry have gained significant market share. The Laminates chapter mainly describes the manufacture of decorative laminates especially the impregnation and pressing process with special emphasis to new technological developments and recent trends. Moreover, the different types of laminates are introduced, combined with some brief comments as they relate to the market for decorative surfaces.
Lund, Erik
2017-01-01
This work extends the Discrete Material and Thickness Optimization approach to structural optimization problems where strength considerations in the form of failure criteria are taken into account for laminated composite structures. It takes offset in the density approaches applied for stress...... constrained topology optimization of single-material problems and develops formulations for multi-material topology optimization problems applied for laminated composite structures. The method can be applied for both stress- and strain-based failure criteria. The large number of local constraints is reduced...
Gökay Nemli
2004-04-01
Full Text Available Wood based panel producers afford to present their products either in sized semi-finished form or as covered in general by the in additional investments realized. The fact that the laminated material has a certain market share as well as the increase in demand for furniture types finished in various profiles have put the laminated sheets which provide very comprehensive design facilities at the top place and caused such boards to spread over the market rather more quickly. In line with this development, great developments have also been recorded during recent years in laminate utilization in furniture factoring sector and fast steps taken towards a more rational working environment. In this study, laminates types and manufacturing technologies were investigated.
Yuan, Chongxin; Roozen, Bert; Bergsma, Otto; Beukers, Adriaan
2012-01-01
The fuselages of aircraft are modeled as a cylinder in this paper, and the sound insulations of a sandwich cylinder and a laminated cylinder are studied both experimentally and numerically. The cylinders are excited by an acoustic pressure and a mechanical force respectively. Results show that under acoustic excitation, the sandwich cylinder and the laminated one have a similar sound insulation below 3000 Hz, but the sandwich cylinder has a much larger sound insulation at higher frequencies. ...
Free and Forced Vibrations of Thick-Walled Anisotropic Cylindrical Shells
Marchuk, A. V.; Gnedash, S. V.; Levkovskii, S. A.
2017-03-01
Two approaches to studying the free and forced axisymmetric vibrations of cylindrical shell are proposed. They are based on the three-dimensional theory of elasticity and division of the original cylindrical shell with concentric cross-sectional circles into several coaxial cylindrical shells. One approach uses linear polynomials to approximate functions defined in plan and across the thickness. The other approach also uses linear polynomials to approximate functions defined in plan, but their variation with thickness is described by the analytical solution of a system of differential equations. Both approaches have approximation and arithmetic errors. When determining the natural frequencies by the semi-analytical finite-element method in combination with the divide and conqure method, it is convenient to find the initial frequencies by the finite-element method. The behavior of the shell during free and forced vibrations is analyzed in the case where the loading area is half the shell thickness
Rate of solidification of aluminium casting in varying wall thickness of cylindrical metallic moulds
Katsina Christopher BALA
2014-02-01
Full Text Available The quality of final casting mainly depends on the rate of solidification as rapid solidification produces fine grains structures with better mechanical properties. The analysis of heat transfer during the casting and solidification of aluminium alloy as well as the experimental investigation of the rate of solidification in varying thicknesses of cylindrical metallic mould was carried out. The temperature variation with time of the casting was recorded from which cooling curves were obtained for the determination of solidification time of the cast. The results showed that as the cylindrical mould thickness increases the solidification time decreases due to the chilling effect of the mould.
Sadighi, M.; Pärnänen, T.; Alderliesten, R.C.; Sayeaftabi, M.; Benedictus, R.
2012-01-01
The impact response of fiber metal laminates (FMLs), has been investigated with experiments and numerical simulations, which is reported in this article. Low-velocity impacts were carried out to study the effects of metal type and thickness within FMLs. Glare5-3/2 laminates with two aluminum layer
Sørensen, Søren Nørgaard; Lund, Erik
2012-01-01
This work concerns a novel large-scale multi-material topology optimization method for simultaneous determination of the optimum variable integer thickness and fiber orientation throughout laminate structures with fixed outer geometries while adhering to certain manufacturing constraints....... The conceptual combinatorial/integer problem is relaxed to a continuous problem and solved on basis of the so-called Discrete Material Optimization method, explicitly including the manufacturing constraints as linear constraints....
Nielsen, Michael Wenani; Schmidt, Jacob Wittrup; Hattel, Jesper Henri
2012-01-01
For large composite structures, such as wind turbine blades, thick laminates are required to withstand large in-service loads. During the manufacture of thick laminates, one of the challenges met is avoiding process-induced shape distortions and residual stresses. In this paper, embedded fibre...... Bragg grating sensors are used to monitor process-induced strains during vacuum infusion of a thick glass/epoxy laminate. The measured strains are compared with predictions from a cure hardening instantaneous linear elastic (CHILE) thermomechanical numerical model where different mechanical boundary...... conditions are employed. The accuracy of the CHILE model in predicting process-induced internal strains, in what is essentially a viscoelastic boundary value problem, is investigated. A parametric study is furthermore performed to reveal the effect of increasing the laminate thickness. The numerical model...
Yu, Hailiang; Lu, Cheng; Tieu, A. Kiet; Li, Huijun; Godbole, Ajit; Kong, Charlie
2018-06-01
The roll bonding technique is one of the most widely used methods to produce metal laminate sheets. Such sheets offer interesting research opportunities for both scientists and engineers. In this paper, we report on an experimental investigation of the 'thickness effect' during laminate rolling for the first time. Using a four-high multifunction rolling mill, Cu/Al/Cu laminate sheets were fabricated with a range of thicknesses (16, 40, 70 and 130 μm) of the Al layer. The thickness of the Cu sheets was a constant 300 μm. After rolling, TEM images show good bonding quality between the Cu and Al layers. However, there are many nanoscale pores in the Al layer. The fraction of nanoscale pores in the Al layer increases with a reduction in the Al layer thickness. The finite element method was used to simulate the Cu/Al/Cu rolling process. The simulation results reveal the effect of the Al layer thickness on the deformation characteristics of the Cu/Al/Cu laminate. Finally, we propose that the size effect of the Al layer thickness during Cu/Al/Cu laminate rolling may offer a method to fabricate 'nanoporous' Al sandwich laminate foils. Such foils can be used in electromagnetic shielding of electrical devices and noisy shielding of building.
Reddy, J N; Chao, W C [Virginia Polytechnic Inst. and State Univ., Blacksburg (USA). Dept. of Engineering Science and Mechanics
1981-04-01
In this study the effects of reduced integration, mesh size, and element type (i.e. linear or quadratic) on the accuracy of a penalty-finite element based on the theory governing thick, laminated, anisotropic composite plates are investigated. In order to assess the accuracy of the present finite element, exact closed-form solutions are developed for cross-ply and antisymmetric angle-ply rectangular plates simply supported and subjected to sinusoidally distributed mechanical and/or thermal loadings, and free vibration.
Srividya, K.; Reddy, Ch. Kishore; Sumanth, Ch. Mohan; Krishnaiah, P. Gopala; Kishan, V. Mallikharjuna
2018-04-01
The present investigation deals with the free vibration analysis of a thick four-layered symmetric cross-ply skew laminated composite plate with a circular cutout. Three dimensional finite element models (FEM) which use the elasticity theory for the determination of stiffness matrices are modeled in ANSYS software to evaluate first five natural frequencies of the laminate. The variations of the first five natural frequencies with respect to length to thickness ratio (S) for different diameter to length ratios (d/l) are presented. It is observed that, the natural frequencies decreases with increase of thickness ratio(S).
Modak, Partha; Hossain, M. Jamil, E-mail: jamil917@gmail.com; Ahmed, S. Reaz [Department of Mechanical Engineering, Bangladesh University of Engineering and Technology, Dhaka 1000 (Bangladesh)
2016-07-12
An accurate stress analysis has been carried out to investigate the suitability of a hybrid balanced laminate as a structural material for thick composite beams with axial stiffeners. Three different balanced laminates composed of dissimilar ply material as well as fiber orientations are considered for a thick beam on simple supports with stiffened lateral ends. A displacement potential based elasticity approach is used to obtain the numerical solution of the corresponding elastic fields. The overall laminate stresses as well as individual ply stresses are analysed mainly in the perspective of laminate hybridization. Both the fiber material and ply angle of individual laminas are found to play dominant roles in defining the design stresses of the present composite beam.
Sharma, Suresh K.; Sankar, Bhavani V.
1995-01-01
This study investigated the effects of through-the-thickness stitching on impact damage resistance, impact damage tolerance, and mode I and mode II fracture toughness of textile graphite/epoxy laminates. Uniweave resin-transfer-molded 48 ply graphite/epoxy (AS4/3501-6) laminates were stitched with Kevlar and glass yarns of different linear densities and stitch spacings. Delaminations were implanted during processing to simulate impact damage. Sublaminate buckling tests were performed to determine the effects of stitching on the compressive strength. The results showed outstanding improvements of up to 400 percent in the compression strength over the unstitched laminates. In impact and static indentation tests the onset of damage occurred at the same level, but the extent of damage was less in stitched laminates. Mode I fracture toughness of 24 ply Uniweave unidirectional (AS4/3501-6) stitched laminates was measured by conducting double-cantilever-beam tests. The critical strain energy release rate (G(sub Ic)) was found to be up to 30 times higher than the unstitched laminates. Mode II fracture toughness of the Uniweave laminates was measured by performing end-notched-flexure tests. Two new methods to compute the apparent G(sub IIc) are presented. The apparent G(sub IIc) was found to be at least 5-15 times higher for the stitched laminates.
Morales Crespo, R.; Fernandez Palop, J.I.; Hernandez, M.A.; Borrego del Pino, S.; Diaz-Cabrera, J.M.; Ballesteros, J.
2006-01-01
In this paper, the floating potential, for cylindrical and spherical Langmuir probes immersed into an electronegative plasma, is determined by using a radial model described in a previous paper. This floating potential is determined for several probe radius values and ranks of plasma electronegativity, from almost electropositive plasmas to high electronegative plasmas. The thickness of the positive ion sheath is also determined for this kind of probes in electronegative plasmas, as well as the analytical expressions fitting this thickness, showing its dependence on the probe radius and electric potential
Nemeth, Michael P.; Schultz, Marc R.
2012-01-01
A detailed exact solution is presented for laminated-composite circular cylinders with general wall construction and that undergo axisymmetric deformations. The overall solution is formulated in a general, systematic way and is based on the solution of a single fourth-order, nonhomogeneous ordinary differential equation with constant coefficients in which the radial displacement is the dependent variable. Moreover, the effects of general anisotropy are included and positive-definiteness of the strain energy is used to define uniquely the form of the basis functions spanning the solution space of the ordinary differential equation. Loading conditions are considered that include axisymmetric edge loads, surface tractions, and temperature fields. Likewise, all possible axisymmetric boundary conditions are considered. Results are presented for five examples that demonstrate a wide range of behavior for specially orthotropic and fully anisotropic cylinders.
DMTO – a method for Discrete Material and Thickness Optimization of laminated composite structures
Sørensen, Søren Nørgaard; Sørensen, Rene; Lund, Erik
2014-01-01
This paper presents a gradient based topology optimization method for Discrete Material and Thickness Optimization of laminated composite structures, labelled the DMTOmethod. The capabilities of the proposed method are demonstrated on mass minimization, subject to constraints on the structural...... criteria; buckling load factors, eigenfrequencies, and limited displacements. Furthermore, common design guidelines or rules, referred to as manufacturing constraints, are included explicitly in the optimization problem as series of linear inequalities. The material selection and thickness variation...... to manufacturability. The results will thus give insight into the relation between potential weight saving and design complexity. The results show that the DMTO method is capable of solving the problems robustly with only few intermediate valued design variables....
Kuzelka, V.; Neuman, F.; Pecinka, L.
1983-01-01
This paper presents the results of experiments concerning the influence of thickness and viscosity of inner and outer annular layers of a liquid on the dynamic behaviour of a cylindrical shell, and a mathematical model of the problem based on acoustic approach is formulated to compare experimental and theoretical results. The measurements of natural frequencies and of damping ratios of a cylindrical shell were carried out with water and with two kinds of mineral oils of different viscosities. The results point towards the fact that with a decreasing thickness of the liquid layer the influence of the added liquid mass increases and the frequency drop is higher. On the other hand there is a certain relative magnitude of the surrounding medium at which the system behaves as an unlimited one. This magnitude depends on the mode order. The statement that the lesser is the thickness of the annular liquid layer the more important is its influence and the larger is the added liquid mass holds up to a certain thickness of the gap, comparable with the thickness of the thin liquid layer on the surface of the shell in which there has not yet been formed a transverse wave. The flowing in this layer is not potential. The governing equation for the description of this problem then is not Euler equation but Stokes's and Helmholtz's theorems for whirling motion. The thickness of the surface layer depends on the viscosity of the liquid. The frequencies measured for the least gap for water were well identified, while for both the mineral oils were chaotical, without any conspicuous resonances. (orig./GL)
S. Riedel
2016-09-01
Full Text Available Ferroelectric properties in hafnium oxide based thin films have recovered the scaling potential for ferroelectric memories due to their ultra-thin-film- and CMOS-compatibility. However, the variety of physical phenomena connected to ferroelectricity allows a wider range of applications for these materials than ferroelectric memory. Especially mixed HfxZr1-xO2 thin films exhibit a broad compositional range of ferroelectric phase stability and provide the possibility to tailor material properties for multiple applications. Here it is shown that the limited thermal stability and thick-film capability of HfxZr1-xO2 can be overcome by a laminated approach using alumina interlayers.
Rodríguez-Orejón, A.
2014-06-01
Full Text Available nvironmental protection involves the reuse of construction and demolition waste. In order to improve recycling, waste from laminated plasterboards is used in the cement and laminated gypsum boards manufacture.This article analyzes the use of ground and burnt laminated plasterboard (BLG waste mixed with thick gypsum (TG. Physical-mechanical characterization of superficial hardness and mechanical strength has been performed on different batches of plaster powder materials with different BLG waste particle sizes to determine its suitability. Coarse particle sizes were preferred in order to reduce the waste treatment. From all the mixtures studied, the one with the best results was TG + 5% BLG1.25 which forms a material of higher superficial hardness and strength. The results obtained in the study have proved suitable products for building use (both as renders and as prefabricated elements enabling for a reduction in the consumption of natural resources.La protección del medio ambiente implica la reutilización de los residuos de construcción y demolición. Los residuos de placas de yeso laminado se utilizan en la fabricación de cemento y de placas de yeso laminado. En este artículo se ha estudiado la utilización deresiduos de placa de yeso laminado cocido (YLC mezclado con yeso grueso (YG, realizándose la caracterización físico-mecánica de dureza superficial y resistencias mecánicas, para determinar su idoneidad formando materiales de yeso en polvo con distintas granulometrías de residuos de (YLC, teniendo preferencia por granulometrías gruesas, que reducen el tratamiento del residuo. De las mezclas estudiadas la que mejores resultados ha ofrecido es YG + 5%YLC1,25 formando un material de mayor dureza superficial y resistencia. De los resultados obtenidos en el estudio se puede afirmar que se han conseguido productos aptos para su utilización en edificación posibilitando una reducción del consumo de recursos naturales.
Compression of thick laminated composite beams with initial impact-like damage
Breivik, N. L.; Guerdal, Z.; Griffin, O. H., Jr.
1992-01-01
While the study of compression after impact of laminated composites has been under consideration for many years, the complexity of the damage initiated by low velocity impact has not lent itself to simple predictive models for compression strength. The damage modes due to non-penetrating, low velocity impact by large diameter objects can be simulated using quasi-static three-point bending. The resulting damage modes are less coupled and more easily characterized than actual impact damage modes. This study includes the compression testing of specimens with well documented initial damage states obtained from three-point bend testing. Compression strengths and failure modes were obtained for quasi-isotropic stacking sequences from 0.24 to 1.1 inches thick with both grouped and interspersed ply stacking. Initial damage prior to compression testing was divided into four classifications based on the type, extent, and location of the damage. These classifications are multiple through-thickness delaminations, isolated delamination, damage near the surface, and matrix cracks. Specimens from each classification were compared to specimens tested without initial damage in order to determine the effects of the initial damage on the final compression strength and failure modes. A finite element analysis was used to aid in the understanding and explanation of the experimental results.
Tseng, Chien-Hsun
2018-06-01
This paper aims to develop a multidimensional wave digital filtering network for predicting static and dynamic behaviors of composite laminate based on the FSDT. The resultant network is, thus, an integrated platform that can perform not only the free vibration but also the bending deflection of moderate thick symmetric laminated plates with low plate side-to-thickness ratios (< = 20). Safeguarded by the Courant-Friedrichs-Levy stability condition with the least restriction in terms of optimization technique, the present method offers numerically high accuracy, stability and efficiency to proceed a wide range of modulus ratios for the FSDT laminated plates. Instead of using a constant shear correction factor (SCF) with a limited numerical accuracy for the bending deflection, an optimum SCF is particularly sought by looking for a minimum ratio of change in the transverse shear energy. This way, it can predict as good results in terms of accuracy for certain cases of bending deflection. Extensive simulation results carried out for the prediction of maximum bending deflection have demonstratively proven that the present method outperforms those based on the higher-order shear deformation and layerwise plate theories. To the best of our knowledge, this is the first work that shows an optimal selection of SCF can significantly increase the accuracy of FSDT-based laminates especially compared to the higher order theory disclaiming any correction. The highest accuracy of overall solution is compared to the 3D elasticity equilibrium one.
Grigorenko, A. Ya.; Borisenko, M. Yu.; Boichuk, E. V.; Prigoda, A. P.
2018-01-01
The dynamic characteristics of a thick-walled cylindrical shell are determined numerically using the finite-element method implemented with licensed FEMAR software. The natural frequencies and modes are compared with those obtained earlier experimentally by the method of stroboscopic holographic interferometry. Frequency coefficients demonstrating how the natural frequency depends on the physical and mechanical parameters of the material are determined.
SMILE: test to validate the WPS effect with a cylindrical thick-walled specimen
Bezdikian, G.; Moinereau, D.; Roos, E.; Kerkhof, K.; Taylor, N.
2004-01-01
The Reactor Pressure Vessel (RPV) is an essential component, which is liable to limit the lifetime duration of PWR plants. The assessment of defects in RPV subjected to pressurized thermal shock (PTS) transients made at an European level generally does not necessarily consider the beneficial effect of the load history (Warm Pre-stress, WPS). The SMILE project - Structural Margin Improvements in aged embrittled RPV with Load history Effects - aims to give sufficient elements to demonstrate, to model and to validate the beneficial WPS effect. It also aims to harmonize the different approaches in the national codes and standards regarding the inclusion of the WPS effect in a RPV structural integrity assessment. The project includes significant experimental work on WPS type experiments with C(T) specimens and a PTS type transient experiment on a large component. This paper deals with the results of the PTS type transient experiment on a component-like, specimen subjected to WPS-loading, the so called Validation Test, carried out within the framework of work package WP4. The test specimen consists of a cylindrical thickwalled specimen with a thickness of 40 mm and an outer diameter of 160 mm, provided with an internal fully circumferential crack with a depth of about 15 mm. The specified load path type is Load-Cool-Unload-Fracture (LCUF). (orig.)
Sørensen, Rene; Lund, Erik
2013-01-01
. The reformulation eliminates the need for having explicit constraint for ensuring that intermediate void does not appear in between layers of the laminate. This is achieved by utilizing a filtering technique known as a casting constraint from traditional topology optimization with isotropic materials....
Harris, W F
1989-03-01
The exact equation for sagitta of spherical surfaces is generalized to toric surfaces which include spherical and cylindrical surfaces as special cases. Lens thickness, therefore, can be calculated accurately anywhere on a lens even in cases of extreme spherical and cylindrical powers and large diameters. The sagittae of tire- and barrel-form toric surfaces differ off the principal meridians, as is shown by a numerical example. The same holds for pulley- and capstan-form toric surfaces. A general expression is given for thickness at an arbitrary point on a toric lens. Approximate expressions are derived and re-expressed in terms of matrices. The matrix provides an elegant means of generalizing equations for spherical surfaces and lenses to toric surfaces and lenses.
Bordo, Vladimir
2011-01-01
The rigorous analytical theory of light transmission through a cylindrical hole of arbitrary diameter in an optically thick film is developed. The approach is based on the introduction of fictitious surface currents at both hole openings and both film surfaces. The solution of Maxwell’s equations...... the film thickness considerably exceeds the hole diameter. It is emphasized that a specific pole corresponding to excitation of surface plasmon polaritons does not appear in the analysis. The theory is illustrated by the calculation of light transmission through a subwavelength hole in an Ag film....
Kim, Jae-Ho; Seong, Tae-Yeon; Ahn, Kyung-Jun; Chung, Kwun-Bum; Seok, Hae-Jun; Seo, Hyeong-Jin; Kim, Han-Ki
2018-05-01
We report the characteristics of Sn-doped In2O3 (ITO) films intended for use as transparent conducting electrodes; the films were prepared via a five-generation, in-line type, cylindrical, rotating magnetron sputtering (CRMS) system as a function of film thickness. By using a rotating cylindrical ITO target with high usage (∼80%), we prepared high conductivity, transparent ITO films on five-generation size glass. The effects of film thickness on the electrical, optical, morphological, and structural properties of CRMS-grown ITO films are investigated in detail to correlate the thickness and performance of ITO films. The preferred orientation changed from the (2 2 2) to the (4 0 0) plane with increasing thickness of ITO is attributed to the stability of the (4 0 0) plane against resputtering during the CRMS process. Based on X-ray diffraction, surface field emission scanning electron microscopy, and cross-sectional transmission electron microscopy, we suggest a possible mechanism to explain the preferred orientation and effects of film thickness on the performance of CRMS-grown ITO films.
Meshless Solution of the Problem on the Static Behavior of Thin and Thick Laminated Composite Beams
Xiang, S.; Kang, G. W.
2018-03-01
For the first time, the static behavior of laminated composite beams is analyzed using the meshless collocation method based on a thin-plate-spline radial basis function. In the approximation of a partial differential equation by using a radial basis function, the shape parameter has an important role in ensuring the numerical accuracy. The choice of a shape parameter in the thin plate spline radial basis function is easier than in other radial basis functions. The governing differential equations are derived based on Reddy's third-order shear deformation theory. Numerical results are obtained for symmetric cross-ply laminated composite beams with simple-simple and cantilever boundary conditions under a uniform load. The results found are compared with available published ones and demonstrate the accuracy of the present method.
Ben Elbahri, M.; Kahouli, A.; Mercey, B.; Lebedev, O.; Donner, W.; Lüders, U.
2018-02-01
Dielectrics based on amorphous sub-nanometric laminates of TiO2 and Al2O3 are subject to elevated dielectric losses and leakage currents, in large parts due to the extremely thin individual layer thickness chosen for the creation of the Maxwell-Wagner relaxation and therefore the high apparent dielectric constants. The optimization of performances of the laminate itself being strongly limited by this contradiction concerning its internal structure, we will show in this study that modifications of the dielectric stack of capacitors based on these sub-nanometric laminates can positively influence the dielectric losses and the leakage, as for example the nature of the electrodes, the introduction of thick insulating layers at the laminate/electrode interfaces and the modification of the total laminate thickness. The optimization of the dielectric stack leads to the demonstration of a capacitor with an apparent dielectric constant of 90, combined with low dielectric loss (tan δ) of 7 · 10-2 and with leakage currents smaller than 1 × 10-6 A cm-2 at 10 MV m-1.
Mechanics of Through-Thickness Reinforced Laminates: Delamination and Dynamic Response
Massabo, Roberta
2002-01-01
Through-thickness reinforcement (stitching, z-pins, weaving) is a promising technology to develop fall-safe load bearing components for aeronautical structures and lightweight armor and combat vehicles with superior capabilities...
Spatial Evolution of the Thickness Variations over a CFRP Laminated Structure
Davila, Yves; Crouzeix, Laurent; Douchin, Bernard; Collombet, Francis; Grunevald, Yves-Henri
2017-10-01
Ply thickness is one of the main drivers of the structural performance of a composite part. For stress analysis calculations (e.g., finite element analysis), composite plies are commonly considered to have a constant thickness compared to the reality (coefficients of variation up to 9% of the mean ply thickness). Unless this variability is taken into account reliable property predictions cannot be made. A modelling approach of such variations is proposed using parameters obtained from a 16-ply quasi-isotropic CFRP plate cured in an autoclave. A discrete Fourier transform algorithm is used to analyse the frequency response of the observed ply and plate thickness profiles. The model inputs, obtained by a mathematical representation of the ply thickness profiles, permit the generation of a representative stratification considering the spatial continuity of the thickness variations that are in good agreement with the real ply profiles spread over the composite part. A residual deformation FE model of the composite plate is used to illustrate the feasibility of the approach.
Golmakani, M. E.; Far, M. N. Sadraee; Moravej, M. [Dept. of Mechanical Engineering, Mashhad Branch, Islamic Azad University, Mashhad (Iran, Islamic Republic of)
2016-12-15
Using new approach proposed by Dynamic relaxation (DR) method, buckling analysis of moderately thick Functionally graded (FG) cylindrical panels subjected to axial compression is investigated for various boundary conditions. The mechanical properties of FG panel are assumed to vary continuously along the thickness direction by the simple rule of mixture and Mori-Tanaka model. The incremental form of nonlinear formulations are derived based on First-order shear deformation theory (FSDT) and large deflection von Karman equations. The DR method combined with the finite difference discretization technique is employed to solve the incremental form of equilibrium equations. The critical mechanical buckling load is determined based on compressive load-displacement curve by adding the incremental displacements in each load step to the displacements obtained from the previous ones. A detailed parametric study is carried out to investigate the influences of the boundary conditions, rule of mixture, grading index, radius-to-thickness ratio, length-to-radius ratio and panel angle on the mechanical buckling load. The results reveal that with increase of grading index the effect of radius-to-thickness ratio on the buckling load decreases. It is also observed that effect of distribution rules on the buckling load is dependent to the type of boundary conditions.
da Cunha, Leonardo Fernandes; Pedroche, Lorena Oliveira; Gonzaga, Carla Castiglia; Furuse, Adilson Yoshio
2014-12-01
Ceramic veneers of minimum thickness provide satisfactory esthetic outcomes while preserving the dental structure. Dental ceramics can both improve the esthetic appearance and reestablish the strength and function of teeth. In worn anterior teeth, functional surfaces, for example, anterior and lateral guidance, can be restored effectively. The characteristics of dental ceramics, such as color stability and mechanical and optical properties, make this material a good choice for indirect restorations, especially when optimum function and esthetics are required. This clinical report presents an occlusal, periodontal, and restorative solution with minimum thickness glass ceramic veneers for worn anterior teeth with multiple diastemas. Copyright © 2014 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.
Hassan Zafarmand
Full Text Available AbstractIn this paper three dimensional free vibration and transient response of a cylindrical panel made of two directional functionally graded materials (2D-FGMs based on three dimensional equations of elasticity and subjected to internal impact loading is considered. Material properties vary through both radial and axial directions continuously. The 3D graded finite element method (GFEM based on Rayleigh-Ritz energy formulation and Newmark direct integration method has been applied to solve the equations in space and time domains. The fundamental normalized natural frequency, time history of displacements and stresses in three directions and velocity of radial stress wave propagation for various values of span angel of cylindrical panel and different power law exponents have been investigated. The present results show that using 2D-FGMs leads to a more flexible design than conventional 1D-FGMs. The GFEM solution have been compared with the results of an FG thick hollow cylinder and an FG curved panel, where a good agreement between them is observed.
Ramazan Kurt,
2012-07-01
Full Text Available Laminated veneer lumbers (LVLs were manufactured from half-round sliced I-214 hybrid poplar clone veneers with MUF adhesives using press pressures ranging from 2.5 to 15 kg cm-2. The results showed that the press pressures affected the glue line thickness (GLT and the physical and mechanical properties of the LVLs. Higher specific gravity (SG and mechanical properties, but lower GLT were developed as a result of using higher press pressures. The optimum press pressure was found to be 10 kg cm-2 in relation to GLT, SG, and mechanical properties. Significant linear correlations were found between GLT and mechanical properties. GLT can be used to determine the quality of wood bonding and may become a valuable tool for this purpose. Reliable data on the optimum GLT and press pressures can be used to design safe wood bonding applications in all aspects of wood based composites, as well as wood constructions when appropriate techniques are adopted to measure the GLT.
Dongyan Shi
2017-01-01
Full Text Available An improved Fourier series method (IFSM is applied to study the free and forced vibration characteristics of the moderately thick laminated composite rectangular plates on the elastic Winkler or Pasternak foundations which have elastic uniform supports and multipoints supports. The formulation is based on the first-order shear deformation theory (FSDT and combined with artificial virtual spring technology and the plate-foundation interaction by establishing the two-parameter foundation model. Under the framework of this paper, the displacement and rotation functions are expressed as a double Fourier cosine series and two supplementary functions which have no relations to boundary conditions. The Rayleigh-Ritz technique is applied to solve all the series expansion coefficients. The accuracy of the results obtained by the present method is validated by being compared with the results of literatures and Finite Element Method (FEM. In this paper, some results are obtained by analyzing the varying parameters, such as different boundary conditions, the number of layers and points, the spring stiffness parameters, and foundation parameters, which can provide a benchmark for the future research.
Hu, Shoufeng; Nairn, John A.
1992-01-01
An analytical method for calculating thermally-induced residual stresses in laminated plates is applied to cross-ply PEEK laminates. We considered three cooling procedures: slow cooling (uniform temperature distribution); convective and radiative cooling; and rapid cooling by quenching (constant surface temperature). Some of the calculated stresses are of sufficient magnitude to effect failure properties such as matrix microcracking.
Renganathan, K.; Nageswara Rao, B.; Jana, M.K. [Vikram Sarabhai Space Centre, Trivandrum (India). Structural Engineering Group
2000-09-01
A solid propellant rocket motor can be considered to be made of various circumferential layers of different properties. A simple procedure is described here to obtain an analytical solution for the general case of multilayered thick cyclindrical shell for internal pressure and thermal loads. This analytical procedure is useful in the preliminary design analysis of solid propellant rocket motors. Since solid propellant material is of viscoelastic behaviour an approximate viscoelastic solution methodology for the multilayered shell is described for estimation of time dependent solutions of propellant grain in a rocket motor. The analytical solution for a two layer reinforced thick cylindrical shell available in the literature is shown to be a special case of the present analytical solution. The results from the present analytical solution for multilayers is found to be in good agreement with FEA results. (orig.) [German] Der grundlegende Aufbau von Feststoffraketenmotoren kann auf einen Zylinder aus mehreren Schichten mit unterschiedlichen Eigenschaften zurueckgefuehrt werden. Eine einfache Berechnungsprozedur fuer die analytische Loesung des allgemeinen Falles eines mehrschichtigen Zylinders unter innerem Druck und thermischer Belastung wird hier vorgestellt. Diese analytische Methodik ist fuer den Auslegungsprozess von Feststoffraketenmotoren von grundlegender Bedeutung. Das viskoelastische Fliessverhalten des festen Brennstoffes, das den zeitlichen Ablauf des Verbrennungsprozesses wesentlich bestimmt, wird durch ein Naeherungsverfahren gut erfasst. Ein in der Literatur enthaltenes spezielles Ergebnis fuer einen zweischaligen verstaerkten Zylinder ergibt sich als Sonderfall der hier vorgestellten Methodik. Die analytisch erhaltenen Loesungen fuer mehrschichtige Aufbauten sind in guter Uebereinstimmung mit mittels der FEM ermittelten Ergebnisse. (orig.)
Dickerson, G. E. (Inventor)
1977-01-01
A process was developed for preparing relatively thick composite laminate structure wherein thin layers of prepreg tapes are assembled, these thin layers are cut into strips that are partially cured, and stacked into the desired thickness with uncured prepreg disposed between each layer of strips. The formed laminate is finally cured and thereafter machined to the desired final dimensions.
Construction of self-supporting cylindrical multiwire proportional chambers
Kobayashi, Masaaki; Fujitani, Takeo; Omori, Tsunehiko; Sugimoto, Shojiro; Yamaguchi, Yoshitake; Nakagawa, Yuji; Wada, Toshiaki.
1984-08-01
Cylindrical MWPC's have been constructed with 240-430 mm in anode diameter and 750 mm in length. They are supported by inner and outer cathode cylinders made of approximately 6 mm thick aramid fibre/phenolic resin honeycomb, sandwiched between 50 μm thick Kapton sheets with or without Cu strips laminated to them. The chambers have been successfully used throughout the E68(P-barPC) experiment at the KEK 12 GeV Proton Synchrotrons. Constructional details are described. (author)
Vibration and Energy Dissipation of Nanocomposite Laminates for Below Ballistic Impact Loading
G. Balaganesan
Full Text Available Abstract Composite laminates are made of glass woven roving mats of 610gsm, epoxy resin and nano clay which are subjected to projectile impact. Nano clay dispersion is varied from 1% to 5%. Impact tests are conducted in a gas gun setup with a spherical nose cylindrical projectile of diameter 9.5 mm of mass 7.6 g. The energy absorbed by the laminates when subjected to impact loading is studied, the velocity range is below ballistic limit. The effect of nano clay on energy absorption in vibration, delamination and matrix crack is studied for different weight % of nano clay and for different thickness values of the laminates. The natural frequencies and damping factors are obtained for the laminates during impact and the effect of nano clay is studied. The results show considerable improvement in energy absorption due to the presence of nano clay
Matsuda, Akihiro; Yabana, Shuichi
2000-01-01
In this report, to evaluate creep properties and effects of creep deformation on mechanical properties of thick rubber bearings for three-dimensional isolation system, we show results of compression creep test for rubber bearings of various rubber materials and shapes and development of numerical simulation method. Creep properties of thick rubber bearings were obtained from compression creep tests. The creep strain shows steady creep that have logarithmic relationships between strain and time and accelerated creep that have linear relationships. We make numerical model of a rubber material with nonlinear viscoelastic constitutional equations. Mechanical properties after creep loading test are simulated with enough accuracy. (author)
Gastaldi, Ugo; Averdung, H; Bailey, J; Beer, G A; Dreher, B; Erdman, K L; Klempt, E; Merle, K; Neubecker, K; Sabev, C; Schwenk, H; Wendling, R D; White, B L; Wodrich, R
1978-01-01
The characteristics and performances of a cylindrical multiwire proportional chamber built and used at CERN in experiment S142 for the study of the pp atom spectroscopy are presented. The chamber surrounds a high-pressure gaseous H/sub 2/ target, from which it is separated by a very thin window (6 mu m mylar foil). The active volume (90 cm long; 2 cm thick, internal diameter=30 cm) is divided into 36 equal and independent cells each covering 10 degrees in azimuth. At 4 abs. atm the detection efficiency for X-rays is higher than 20% in the whole energy range 1.5-15 keV. Typical resolutions are 35% fwhm for the 3 ke V Ar fluorescence line and 25% fwhm for the 5.5 keV /sup 54/Mn line. Working pressures from 0.5 to 16 abs. atm have been used. (8 refs).
Melcer, Shai; Gruenbaum, Yosef; Krohne, Georg
2007-01-01
Lamins are the main component of the nuclear lamina and considered to be the ancestors of all intermediate filament proteins. They are localized mainly at the nuclear periphery where they form protein complexes with integral proteins of the nuclear inner membrane, transcriptional regulators, histones and chromatin modifiers. Studying lamins in invertebrate species has unique advantages including the smaller number of lamin genes in the invertebrate genomes and powerful genetic analyses in Caenorhabditis elegans and Drosophila melanogaster. These simpler nuclear lamina systems allow direct analyses of their structure and functions. Here we give an overview of recent advances in the field of invertebrate nuclear lamins with special emphasis on their evolution, assembly and functions
Ridgway, P.C.; Case, D.F.
1979-01-01
In a method of bonding laminations of a magnetic core, photo-resist material consisting of a co-polymer is applied as a film to a sheet of magnetic material to define lamination shapes to enable the laminations to be formed by etching. The film of photo-resist material on the laminations is then utilised to bond the laminations together in a stack. In order to permit the core to operate at temperatures higher than the softening temperature of the photo-resist material, the bonded stack is irradiated with 1 - 2 Mer gamma radiation to a dose of 1 - 5 Mrads in 2 - 10 hrs to cause changes to the bonding material such that the material does not soften at the operating temperature of the core. (U.K.)
Laminated piezoelectric transformer
Vazquez Carazo, Alfredo (Inventor)
2006-01-01
A laminated piezoelectric transformer is provided using the longitudinal vibration modes for step-up voltage conversion applications. The input portions are polarized to deform in a longitudinal plane and are bonded to an output portion. The deformation of the input portions is mechanically coupled to the output portion, which deforms in the same longitudinal direction relative to the input portion. The output portion is polarized in the thickness direction relative its electrodes, and piezoelectrically generates a stepped-up output voltage.
Laser cutting of Kevlar laminates
VanCleave, R.A.
1977-09-01
An investigation has been conducted of the use of laser energy for cutting contours, diameters, and holes in flat and shaped Kevlar 49 fiber-reinforced epoxy laminates as an alternate to conventional machining. The investigation has shown that flat laminates 6.35 mm thick may be cut without backup by using a high-powered (1000-watt) continuous wave CO/sub 2/ laser at high feedrates (33.87 mm per second). The cut produced was free of the burrs and delaminations resulting from conventional machining methods without intimate contact backup. In addition, the process cycle time was greatly reduced.
Vebil Yıldırım
2017-07-01
Full Text Available Heat-induced, pressure-induced, and centrifugal force-induced axisymmetric exact deformation and stresses in a thick-walled spherical vessel, a cylindrical vessel, and a uniform disk are all determined analytically at a specified constant surface temperature and at a constant angular velocity. The inner and outer pressures are both included in the formulation of annular structures made of an isotropic and homogeneous linear elastic material. Governing equations in the form of Euler-Cauchy differential equation with constant coefficients are solved and results are presented in compact forms. For disks, three different boundary conditions are taken into account to consider mechanical engineering applications. The present study is also peppered with numerical results in graphical forms.
A MEMS lamination technology based on sequential multilayer electrodeposition
Kim, Minsoo; Kim, Jooncheol; Herrault, Florian; Schafer, Richard; Allen, Mark G
2013-01-01
A MEMS lamination technology based on sequential multilayer electrodeposition is presented. The process comprises three main steps: (1) automated sequential electrodeposition of permalloy (Ni 80 Fe 20 ) structural and copper sacrificial layers to form multilayer structures of significant total thickness; (2) fabrication of polymeric anchor structures through the thickness of the multilayer structures and (3) selective removal of copper. The resulting structure is a set of air-insulated permalloy laminations, the separation of which is sustained by insulating polymeric anchor structures. Individual laminations have precisely controllable thicknesses ranging from 500 nm to 5 µm, and each lamination layer is electrically isolated from adjacent layers by narrow air gaps of similar scale. In addition to air, interlamination insulators based on polymers are investigated. Interlamination air gaps with very high aspect ratio (>1:100) can be filled with polyvinylalcohol and polydimethylsiloxane. The laminated structures are characterized using scanning electron microscopy and atomic force microscopy to directly examine properties such as the roughness and the thickness uniformity of the layers. In addition, the quality of the electrical insulation between the laminations is evaluated by quantifying the eddy current within the sample as a function of frequency. Fabricated laminations are comprised of uniform, smooth (surface roughness <100 nm) layers with effective electrical insulation for all layer thicknesses and insulator approaches studied. Such highly laminated structures have potential uses ranging from energy conversion to applications where composite materials with highly anisotropic mechanical or thermal properties are required. (paper)
Optimum design of laminated composite under axial compressive load
In the present study optimal design of composite laminates, with and without rectangular cut-out, is carried out for maximizing the buckling load. Optimization study is carried out for obtaining the maximum buckling load with design variables as ply thickness, cut-out size and orientation of cut-out with respect to laminate.
Rippel, Wally E.; Kobayashi, Daryl M.
2005-10-11
An electric motor, transformer or inductor having a lamination cooling system including a stack of laminations, each defining a plurality of apertures at least partially coincident with apertures of adjacent laminations. The apertures define a plurality of cooling-fluid passageways through the lamination stack, and gaps between the adjacent laminations are sealed to prevent a liquid cooling fluid in the passageways from escaping between the laminations. The gaps are sealed by injecting a heat-cured sealant into the passageways, expelling excess sealant, and heat-curing the lamination stack. The apertures of each lamination can be coincident with the same-sized apertures of adjacent laminations to form straight passageways, or they can vary in size, shape and/or position to form non-axial passageways, angled passageways, bidirectional passageways, and manifold sections of passageways that connect a plurality of different passageway sections. Manifold members adjoin opposite ends of the lamination stack, and each is configured with one or more cavities to act as a manifold to adjacent passageway ends. Complex manifold arrangements can create bidirectional flow in a variety of patterns.
Plastic buckling of cylindrical shells
Bandyopadhyay, K.; Xu, J.; Shteyngart, S.; Eckert, H.
1994-01-01
Cylindrical shells exhibit buckling under axial loads at stresses much less than the respective theoretical critical stresses. This is due primarily to the presence of geometrical imperfections even though such imperfections could be very small (e.g., comparable to thickness). Under internal pressure, the shell regains some of its buckling strength. For a relatively large radius-to-thickness ratio and low internal pressure, the effect can be reasonably estimated by an elastic analysis. However, for low radius-to-thickness ratios and greater pressures, the elastic-plastic collapse controls the failure load. in order to quantify the elastic-plastic buckling capacity of cylindrical shells, an analysis program was carried out by use of the computer code BOSOR5 developed by Bushnell of Lockheed Missiles and Space Company. The analysis was performed for various radius-to-thickness ratios and imperfection amplitudes. The purpose of the analytical program was to compute the buckling strength of underground cylindrical tanks, that are used for storage of nuclear wastes, for realistic geometric imperfections and internal pressure loads. This paper presents the results of the elastic-plastic analyses and compares them with other available information for various pressure loads
Minimum weight design of composite laminates for multiple loads
Krikanov, A.A.; Soni, S.R.
1995-01-01
A new design method of constructing optimum weight composite laminates for multiple loads is proposed in this paper. A netting analysis approach is used to develop an optimization procedure. Three ply orientations permit development of optimum laminate design without using stress-strain relations. It is proved that stresses in minimum weight laminate reach allowable values in each ply with given load. The optimum ply thickness is defined at maximum value among tensile and compressive loads. Two examples are given to obtain optimum ply orientations, thicknesses and materials. For comparison purposes, calculations of stresses are done in orthotropic material using classical lamination theory. Based upon these calculations, matrix degrades at 30 to 50% of ultimate load. There is no fiber failure and therefore laminates withstand all applied loads in both examples
Laminated Ti-Al composites: Processing, structure and strength
Du, Yan; Fan, Guohua; Yu, Tianbo
2016-01-01
Laminated Ti-Al composite sheets with different layer thickness ratios have been fabricated through hot pressing followed by multi-pass hot rolling at 500 °C.The laminated sheets show strong bonding with intermetallic interface layers of nanoscale thickness between the layers of Ti and Al....... The mechanical properties of the composites with different volume fractions of Al from 10% to 67% show a good combination of strength and ductility. A constraint strain in the hot-rolled laminated structure between the hard and soft phases introduces an elastic-plastic deformation stage, which becomes more...
Keenan, R.
1985-01-01
Two-piece unit heats and presses protective layers to form laminate. Rubber diaphragm between upper and lower vacuum chambers alternates between neutral position and one that presses against solar-cell array, supplying distributed force necessary to press layers of laminate together. Encapsulation helps to protect cells from environment and to ensure long panel life while allowing efficient generation of electricity from Sunlight.
Mechanical performance of laminated composites incorporated with nanofibrous membranes
Liu, L.; Huang, Z.-M.; He, C.L.; Han, X.J.
2006-01-01
The effect of non-woven nanofibrous membranes as interlaminar interfaces on the mechanical performance of laminated composites was investigated experimentally. The nanofibrous membranes are porous, thin and lightweight, and exhibit toughness and strength to some extent. They give little increase in weight and thickness when incorporated into a laminate. More important, they can be used as a functional agent carrier for the laminate. The nanofiber membranes used in this paper were prepared by electrospinning of Nylon-6 (PA6), Epoxy 609 (EPO 1691-410) and thermoplastic polyurethane (TPU), with a thickness ranging from 20 to 150 μm. The non-woven fabrics were attached to one side of a glass/epoxy fabric lamina prior to lamination and each fabric was arranged in between two adjacent plies of the laminate. The nanofibrous membranes were characterized through scanning electron microscopy (SEM) and tensile testing, whereas the mechanical properties of the laminate were understood in terms of three-point bending and short-beam shear tests. Results have shown that the nanofibrous membranes in the ply interfaces with a proper thickness did not affect the mechanical performance of the composite laminates significantly
The mechanical behavior of GLARE laminates for aircraft structures
Wu, Guocai; Yang, J.-M.
2005-01-01
GLARE (glass-reinforced aluminum laminate) is a new class of fiber metal laminates for advanced aerospace structural applications. It consists of thin aluminum sheets bonded together with unidirectional or biaxially reinforced adhesive prepreg of high-strength glass fibers. GLARE laminates offer a unique combination of properties such as outstanding fatigue resistance, high specific static properties, excellent impact resistance, good residual and blunt notch strength, flame resistance and corrosion properties, and ease of manufacture and repair. GLARE laminates can be tailored to suit a wide variety of applications by varying the fiber/resin system, the alloy type and thickness, stacking sequence, fiber orientation, surface pretreatment technique, etc. This article presents a comprehensive overview of the mechanical properties of various GLARE laminates under different loading conditions.
Study of the Formability of Laminated Lightweight Metallic Materials
Girjob Claudia
2017-01-01
Full Text Available The main objective of this work was to test the formability of laminated materials. Laminated materials are considered a good choice when parts with reduced weight are considered. Thus, a laminated material, aluminum - polypropylene - aluminum (Al-PP-Al, as sheet 1.2 mm and 1.4 mm thickness was used. Before processing the material by means of unconventional plastic deformation, its formability was determined by running the Nakajima test. After obtaining the forming limit curves, the material was machined by means of incremental forming.
Lamination cooling system formation method
Rippel, Wally E [Altadena, CA; Kobayashi, Daryl M [Monrovia, CA
2009-05-12
An electric motor, transformer or inductor having a cooling system. A stack of laminations have apertures at least partially coincident with apertures of adjacent laminations. The apertures define straight or angled cooling-fluid passageways through the lamination stack. Gaps between the adjacent laminations are sealed by injecting a heat-cured sealant into the passageways, expelling excess sealant, and heat-curing the lamination stack. Manifold members adjoin opposite ends of the lamination stack, and each is configured with one or more cavities to act as a manifold to adjacent passageway ends. Complex manifold arrangements can create bidirectional flow in a variety of patterns.
Lamins, laminopathies and disease mechanisms
2011-07-08
Jul 8, 2011 ... Lamins, laminopathies and disease mechanisms: Possible role for proteasomal degradation of ... Mutations in the human lamin genes lead to highly degenerative genetic diseases that affect a number of different ... June 2018.
Arteiro, Albertino; Borstnar, Gregor; Mavrogordato, Mark N.; Sinclair, Ian; Spearing, S. Mark; Camanho, Pedro P.; Cohen, Estelle; Kopp, Reed Alan; Furtado Pereira da Silva, Carolina; Ni, Xinchen; Wardle, Brian L
2017-01-01
Thin-ply carbon fiber laminates have exhibited superior mechanical properties, including higher initiation and ultimate strength, when compared to standard thickness plies and enable greater flexibility in laminate design. However, the increased ply count in thin-ply laminates also increases the number of ply-ply interfaces, thereby increasing the number of relatively weak and delamination-prone interlaminar regions. In this study, we report the first experimental realization of aligned carbo...
EB curable laminating adhesives
Matsuyama, Asao; Kobayashi, Masahide; Gotoh, Sakiko
1992-01-01
New developed solvent free EB curable laminating adhesives have two liquid components, A with hydroxy and acryloyl group, B with isocyanate and acryloyl group in a molecule. These EB laminating adhesives do not need any aging process, which is a big advantage, and are very suitable for environment, safety, and health because of no heating process and solvent free formulas. And we have made basic research about the relation of peel strength or heat seal strength versus Tg of cured film, elongation at break, elastic modulus, and so on. Basic specifications of the new developed adhesives are shown. (author)
Laminated multilayer sheet structure and its utilization
Chiba, K.; Itoh, K.; Mitani, Y.; Sobajima, S.; Yonemura, U.
1980-01-01
A laminated multilayer sheet structure is described comprising (A) an opaque flexible sheet layer, and (B) a flexible layer laminated on the surface of layer (A) and composed of a transparent thermic ray reflecting layer (B 1 ) bonded to a transparent synthetic resin layer (B 2 ), said layer (B 1 ) being a transparent thermic ray reflecting layer composed of (I) a layer of a metal having a thickness of about 50 to about 600 A, said metal being selected from the group consisting of gold, silver, copper, aluminum and a mixture of alloy of at least two of said metals, and (II) a high refractive substance layer having a thickness of about 50 to about 600 A, of an oxide of titanium derived from a layer of an organic titanium compound of the formula Ti 1 O/sub m/R/sub n/, where R is alkyl of 1-20 carbon atoms, l=1-30, m=4+3(1-1), and n=4+2(1-1), and containing the organic residual moiety of the organic titanium compound, the amount of said organic residual moiety being 0.1 to 30% by weight based on the weight of the high refractive substance layer; or said layer (B 1 ) being a transparent semiconductive layer having a thickness of about 500 to about 5,000 a and being composed of a compound selected from the group consisting of indium oxide, tin oxide, cadmium oxide, antimony oxide, copper iodide, and a mixture of at least two of said compounds. A method is described for heat-insulating a room, which comprises applying to the surface of a floor, wall, ceiling or partition in the room a laminated multilayer sheet structure comprising (A) an opaque flexible sheet layer, and (B) a flexible layer laminated on the surface of layer (A) and composed of a transparent thermic ray reflecting layer (B 1 ) bonded to a transparent synthetic resin layer
A historical perspective of laminitis.
Heymering, Henry W
2010-04-01
The causes of laminitis are many-often interrelated, sometimes direct opposites. The history of laminitis has been a search for the cause or causes of laminitis and for effective treatment. Going in and out of fashion, many treatments have lasted for centuries, some for millennia, but very few have been proven. Copyright 2010 Elsevier Inc. All rights reserved.
DESIGN ALTERNATIVES ON THE LAMINATES
Gökay Nemli
2004-04-01
Full Text Available Wood based panel manufacturers use increasing volumes of laminates. Laminates are resistant to the water, humidity, scratch, abrasion, burning and chemicals. These products consist of printed decor papers that have been saturated with thermosetting resin. In this study, laminate types, composition form and design alternatives were investigated.
Mahadev, Sthanu
distinguished with respect to the circumferential arc angle, thickness-to-mean radius ratio and total laminate thickness. The potential of this methodology is challenged to analytically determine the location of the centroid. This precise location dictates the decoupling of extension-bending type deformational response in tension loaded composite structures. Upon the cross-validation of the centroidal point through the implementation of an ANSYS based finite element routine, influence of centroid is analytically examined under the application of a concentrated longitudinal tension and bending type loadings on a series of cylindrical shells characterized by three different symmetric-balanced stacking sequences. In-plane ply-stresses are computed and analyzed across the circumferential contour. An experimental investigation has been incorporated via designing an ad-hoc apparatus and test-up that accommodates the quantification of in-plane strains, computation of ply-stresses and addresses the physical characteristics for a set of auto-clave fabricated cylindrical shell articles. Consequently, this work is shown to essentially capture the mechanical aspects of cylindrical shells, thus facilitating structural engineers to design and manufacture viable structures.
Design and analysis of reactor containment of steel-concrete composite laminated shell
Ichikawa, K.; Isobata, O.; Kawamata, S.
1977-01-01
A new scheme of containment consisting of steel-concrete laminated shell is being developed. In the main part of a cylindrical vessel, the shell consists of two layers of thin steel plates located at the inner and outer surfaces, and a layer of concrete core into which both the steel plates are anchored. Because of the compressive and shearing resistance of the concrete core, the layers behave as a composite solid shell. Membrane forces are shared by steel plates and partly by concrete core. Bending moment is effectively resisted by the section with extreme layers of steel. Therefore, both surfaces can be designed as extremely thin plates: the inner plate, which is a load carrying members as well as a liner, can be welded without the laborious process of stress-relieving, and various jointing methods can be applied to the outer plate which is free from the need for leak tightness. The capability of the composite layers of behaving as a unified solid shell section depends largely on the shearing rigidity of the concrete core. However, as its resisting capacity to transverse shearing force is comparatively low, a device for reducing the shearing stress at the junction to the base mat is needed. In the new scheme, this part of the cylindrical shell is divided into multiple layers of the same kind of composite shell. This device makes the stiffness of the bottom of the cylindrical shell to lateral movement minimum while maintaining the proper resistance to membrane forces. The analysis shows that the transverse shearing stress can be reduced to less than 1√n of the ordinary case by dividing the thickness of the shell into n layers which are able to slip against each other at the contact surface. In order to validate the feasibility and safety of this new design, the results of analysis on the basis of up-to-date design loads are presented
Calculation of deflection for cross laminated timber floor panel
Kozarić Ljiljana M.
2016-01-01
Full Text Available In this paper analytically calculated values of effective flexural stiffness and deflections of five-layer CLT panels height 14 cm due to the payload defined in Eurocode 1 for floors in residential buildings are compared. Effective flexural stiffness was calculated using Gamma method, K-method and Kreuzinger's analogy. Three floor panels with identical height but with different combinations of lamination thicknesses in cross-layers were analyzed. The panels are 4.5 meters long and 1 meter wide. Lamination thicknesses in cross-sections of panels are 33,4 cm+21,9 cm, then 33 cm+22,5 cm and 52,8 cm.
Modeling of Nonlinear Mechanical Response in CFRP Angle-Ply Laminates
Ogihara, Shinji
2014-03-01
It is known that the failure process in angle-ply laminate involves matrix cracking and delamination and that they exhibit nonlinear stress-strain relation. There may be a significant effect of the constituent blocked ply thickness on the mechanical behavior of angle-ply laminates. These days, thin prepregs whose thickness is, for example 50 micron, are developed and commercially available. Therefore, we can design wide variety of laminates with various constituent ply thicknesses. In this study, effects of constituent ply thickness on the nonlinear mechanical behavior and the damage behavior of CFRP angle-ply laminates are investigated experimentally. Based on the experimental results, the mechanical response in CFRP angle-ply laminates is modeled by using the finite strain viscoplasticity model. We evaluated the mechanical behavior and damage behavior in CFRP angle-ply laminates with different constituent ply thickness under tensile loading experimentally. It was found that as the constituent ply thickness decreases, the strength and failure strain increases. We also observed difference in damage behavior. The preliminary results of finite strain viscoplasticity model considering the damage effect for laminated composites are shown. A qualitative agreement is obtained.
Antibubbles and fine cylindrical sheets of air
Beilharz, D.
2015-08-14
Drops impacting at low velocities onto a pool surface can stretch out thin hemispherical sheets of air between the drop and the pool. These air sheets can remain intact until they reach submicron thicknesses, at which point they rupture to form a myriad of microbubbles. By impacting a higher-viscosity drop onto a lower-viscosity pool, we have explored new geometries of such air films. In this way we are able to maintain stable air layers which can wrap around the entire drop to form repeatable antibubbles, i.e. spherical air layers bounded by inner and outer liquid masses. Furthermore, for the most viscous drops they enter the pool trailing a viscous thread reaching all the way to the pinch-off nozzle. The air sheet can also wrap around this thread and remain stable over an extended period of time to form a cylindrical air sheet. We study the parameter regime where these structures appear and their subsequent breakup. The stability of these thin cylindrical air sheets is inconsistent with inviscid stability theory, suggesting stabilization by lubrication forces within the submicron air layer. We use interferometry to measure the air-layer thickness versus depth along the cylindrical air sheet and around the drop. The air film is thickest above the equator of the drop, but thinner below the drop and up along the air cylinder. Based on microbubble volumes, the thickness of the cylindrical air layer becomes less than 100 nm before it ruptures.
Antibubbles and fine cylindrical sheets of air
Beilharz, D.; Guyon, A.; Li, E. Q.; Thoraval, M.-J.; Thoroddsen, Sigurdur T
2015-01-01
Drops impacting at low velocities onto a pool surface can stretch out thin hemispherical sheets of air between the drop and the pool. These air sheets can remain intact until they reach submicron thicknesses, at which point they rupture to form a myriad of microbubbles. By impacting a higher-viscosity drop onto a lower-viscosity pool, we have explored new geometries of such air films. In this way we are able to maintain stable air layers which can wrap around the entire drop to form repeatable antibubbles, i.e. spherical air layers bounded by inner and outer liquid masses. Furthermore, for the most viscous drops they enter the pool trailing a viscous thread reaching all the way to the pinch-off nozzle. The air sheet can also wrap around this thread and remain stable over an extended period of time to form a cylindrical air sheet. We study the parameter regime where these structures appear and their subsequent breakup. The stability of these thin cylindrical air sheets is inconsistent with inviscid stability theory, suggesting stabilization by lubrication forces within the submicron air layer. We use interferometry to measure the air-layer thickness versus depth along the cylindrical air sheet and around the drop. The air film is thickest above the equator of the drop, but thinner below the drop and up along the air cylinder. Based on microbubble volumes, the thickness of the cylindrical air layer becomes less than 100 nm before it ruptures.
Tearing instability in cylindrical plasma configuration
Zelenyj, L.M.
1979-01-01
The effect of the neutral-layer cylindrical geometry on the development of the tearing instability has been investigated in detail. The increments of the instability for all the regimes have been found. The influence of cylindrical effects becomes manifesting itself at small, as compared to the layer characteristic thickness, distances from the axis, and, finally, the electron regime of the instability development transforms into an ion one. The results obtained are of interest for studying the plasma stability in the devices of the ''Astron'' type and in magnetospheres of cosmic objects
Forced Vibration Analysis for a FGPM Cylindrical Shell
Hong-Liang Dai
2013-01-01
Full Text Available This article presents an analytical study for forced vibration of a cylindrical shell which is composed of a functionally graded piezoelectric material (FGPM. The cylindrical shell is assumed to have two-constituent material distributions through the thickness of the structure, and material properties of the cylindrical shell are assumed to vary according to a power-law distribution in terms of the volume fractions for constituent materials, the exact solution for the forced vibration problem is presented. Numerical results are presented to show the effect of electric excitation, thermal load, mechanical load and volume exponent on the static and force vibration of the FGPM cylindrical shell. The goal of this investigation is to optimize the FGPM cylindrical shell in engineering, also the present solution can be used in the forced vibration analysis of cylindrical smart elements.
Tunable characteristics of bending resonance frequency in magnetoelectric laminated composites
Chen Lei; Li Ping; Wen Yu-Mei; Zhu Yong
2013-01-01
As the magnetoelectric (ME) effect in piezoelectric/magnetostrictive laminated composites is mediated by mechanical deformation,the ME effect is significantly enhanced in the vicinity of resonance frequency.The bending resonance frequency (fr) of bilayered Terfenol-D/PZT (MP) laminated composites is studied,and our analysis predicts that (i) the bending resonance frequency of an MP laminated composite can be tuned by an applied dc magnetic bias (Hdc) due to the △E effect; (ii) the bending resonance frequency of the MP laminated composite can be controlled by incorporating FeCuNbSiB layers with different thicknesses.The experimental results show that with Hdc increasing from 0Oe (1 Oe=79.5775 A/m)to 700 Oe,the bending resonance frequency can be shifted in a range of 32.68 kHz ≤ fr ≤ 33.96 kHz.In addition,with the thickness of the FeCuNbSiB layer increasing from 0 μm to 90 μm,the bending resonance frequency of the MP laminated composite gradually increases from 33.66 kHz to 39.18 kHz.This study offers a method of adjusting the strength of dc magnetic bias or the thicknesses of the FeCuNbSiB layer to tune the bending resonance frequency for ME composite,which plays a guiding role in the ME composite design for real applications.
Leung, Ka-Ngo [Hercules, CA
2008-04-22
A cylindrical neutron generator is formed with a coaxial RF-driven plasma ion source and target. A deuterium (or deuterium and tritium) plasma is produced by RF excitation in a cylindrical plasma ion generator using an RF antenna. A cylindrical neutron generating target is coaxial with the ion generator, separated by plasma and extraction electrodes which contain many slots. The plasma generator emanates ions radially over 360.degree. and the cylindrical target is thus irradiated by ions over its entire circumference. The plasma generator and target may be as long as desired. The plasma generator may be in the center and the neutron target on the outside, or the plasma generator may be on the outside and the target on the inside. In a nested configuration, several concentric targets and plasma generating regions are nested to increase the neutron flux.
Balci, Murat [Dept. of Mechanical Engineering, Bayburt University, Bayburt (Turkmenistan); Gundogdu, Omer [Dept. of Mechanical Engineering, Ataturk University, Erzurum (Turkmenistan)
2017-01-15
In this study, estimation of some physical properties of a laminated composite plate was conducted via the inverse vibration problem. Laminated composite plate was modelled and simulated to obtain vibration responses for different length-to-thickness ratio in ANSYS. Furthermore, a numerical finite element model was developed for the laminated composite utilizing the Kirchhoff plate theory and programmed in MATLAB for simulations. Optimizing the difference between these two vibration responses, inverse vibration problem was solved to obtain some of the physical properties of the laminated composite using genetic algorithms. The estimated parameters are compared with the theoretical results, and a very good correspondence was observed.
Balci, Murat; Gundogdu, Omer
2017-01-01
In this study, estimation of some physical properties of a laminated composite plate was conducted via the inverse vibration problem. Laminated composite plate was modelled and simulated to obtain vibration responses for different length-to-thickness ratio in ANSYS. Furthermore, a numerical finite element model was developed for the laminated composite utilizing the Kirchhoff plate theory and programmed in MATLAB for simulations. Optimizing the difference between these two vibration responses, inverse vibration problem was solved to obtain some of the physical properties of the laminated composite using genetic algorithms. The estimated parameters are compared with the theoretical results, and a very good correspondence was observed
Photovoltaic module and laminate
Bunea, Gabriela E.; Kim, Sung Dug; Kavulak, David F.J.
2018-04-10
A photovoltaic module is disclosed. The photovoltaic module has a first side directed toward the sun during normal operation and a second, lower side. The photovoltaic module comprises a perimeter frame and a photovoltaic laminate at least partially enclosed by and supported by the perimeter frame. The photovoltaic laminate comprises a transparent cover layer positioned toward the first side of the photovoltaic module, an upper encapsulant layer beneath and adhering to the cover layer, a plurality of photovoltaic solar cells beneath the upper encapsulant layer, the photovoltaic solar cells electrically interconnected, a lower encapsulant layer beneath the plurality of photovoltaic solar cells, the upper and lower encapsulant layers enclosing the plurality of photovoltaic solar cells, and a homogenous rear environmental protection layer, the rear environmental protection layer adhering to the lower encapsulant layer, the rear environmental protection layer exposed to the ambient environment on the second side of the photovoltaic module.
Theoretical modeling and experimental analyses of laminated wood composite poles
Cheng Piao; Todd F. Shupe; Vijaya Gopu; Chung Y. Hse
2005-01-01
Wood laminated composite poles consist of trapezoid-shaped wood strips bonded with synthetic resin. The thick-walled hollow poles had adequate strength and stiffness properties and were a promising substitute for solid wood poles. It was necessary to develop theoretical models to facilitate the manufacture and future installation and maintenance of this novel...
A theory of piezoelectric laminates
Giangreco, E.
1997-01-01
A theory of piezoelectric laminates is rationally derived from the three-dimensional Voigt theory of piezoelectricity. The present theory is a generalization to piezoelectric laminates of the Reissner-Mindlin-type layer-wise theory of elastic laminates. Both a differential formulation and a variational formulation of the piezoelectric laminate problem are presented. The proposed theory is adopted in the analysis of simple problems, in order to verify its effectiveness. The results it provides turn out to be in good agreement with the results supplied by the Voigt theory of piezoelectricity
Thermoelastic wave propagation in laminated composites plates
Verma K. L.
2012-12-01
Full Text Available The dispersion of thermoelastic waves propagation in an arbitrary direction in laminated composites plates is studied in the framework of generalized thermoelasticity in this article. Three dimensional field equations of thermoelasticity with relaxation times are considered. Characteristic equation is obtained on employing the continuity of displacements, temperature, stresses and thermal gradient at the layers’ interfaces. Some important particular cases such as of free waves on reducing plates to single layer and the surface waves when thickness tends to infinity are also discussed. Uncoupled and coupled thermoelasticity are the particular cases of the obtained results. Numerical results are also obtained and represented graphically.
Bautista, Zhierwinjay; Shin, Hyung Seop [Dept. of Mechanical Design Engineering, Andong National University, Andong (Korea, Republic of); Mean, Byoung Jean; Lee, Jae Hun [SuNAM Co Ltd., Anseong (Korea, Republic of)
2016-12-15
The mechanical properties of REBCO coated conductor (CC) wires under uniaxial tension are largely determined by the thick component layers in the architecture, namely, the substrate and the stabilizer or even the reinforcement layer. Depending on device applications of the CC tapes, it is necessary to reinforce thin metallic foils externally to one-side or both sides of the CC tapes. Due to the external reinforcement of brass foils, it was found that this could increase the reversible strain limit from the Cu-stabilized CC tapes. In this study, the effects of differently hardened brass foil laminate on the electromechanical property of CC tapes were investigated under uniaxial tension loading. The tensile strain dependence of the critical current (I{sub c}) was measured at 77 K and self-field. Depending on whether the I{sub c} of CC tapes were measured during loading or after unloading, a reversible strain (or stress) limit could be determined, respectively. The both-sides of the Cu-stabilized CC tapes were laminated with brass foils with different hardness, namely 1/4H, 1H and EH. From the obtained results, it showed that the yield strength of the brass laminated CC tapes with EH brass foil laminate was comparable to the one of the Cu-stabilized CC tape due to its large yield strength even though its large volume fraction. It was found that the brass foil with different hardness was mainly sensitive on the stress dependence of I{sub c}, but not on the strain sensitivity due to the residual strain induced in the laminated CC tapes during unloading.
Beiermann, Brett A. (Inventor); Keller, Michael W. (Inventor); White, Scott R. (Inventor); Sottos, Nancy R. (Inventor)
2016-01-01
A laminate material may include a first flexible layer, and a self-healing composite layer in contact with the first flexible layer. The composite layer includes an elastomer matrix, a plurality of first capsules including a polymerizer, and a corresponding activator for the polymerizer. The laminate material may self-heal when subjected to a puncture or a tear.
Development of High Performance CFRP/Metal Active Laminates
Asanuma, Hiroshi; Haga, Osamu; Imori, Masataka
This paper describes development of high performance CFRP/metal active laminates mainly by investigating the kind and thickness of the metal. Various types of the laminates were made by hot-pressing of an aluminum, aluminum alloys, a stainless steel and a titanium for the metal layer as a high CTE material, a unidirectional CFRP prepreg as a low CTE/electric resistance heating material, a unidirectional KFRP prepreg as a low CTE/insulating material. The aluminum and its alloy type laminates have almost the same and the highest room temperature curvatures and they linearly change with increasing temperature up to their fabrication temperature. The curvature of the stainless steel type jumps from one to another around its fabrication temperature, whereas the titanium type causes a double curvature and its change becomes complicated. The output force of the stainless steel type attains the highest of the three under the same thickness. The aluminum type successfully increased its output force by increasing its thickness and using its alloys. The electric resistance of the CFRP layer can be used to monitor the temperature, that is, the curvature of the active laminate because the curvature is a function of temperature.
Cox, F.M.; Chamberlain, J.D.; Shrader, E.F.; Shoffner, B.M.; Szalanczy, A.
1975-01-01
A laminated card with one or more apertures, each adapted to peripherally seal an encapsulated dosimeter, is formed by bonding a foraminous, code-adaptable, rigid sheet of low-Z material with a codedly transparent sheet of low-Z material in light-transmitting registry with particular code-holes of the rigid sheet. The laminated card may be coded to identify the person carrying it, and/or the location or circumstances related to its exposure to radiation. This card is particularly adapted for use in an instrument capable of evaluating a multiplicity of cards, substantially continuously. The coded identification from the card may be displayed by an appropriate machine, and if desired an evaluation may be recorded because of a ''parity checking'' system incorporated in each card, which permits ''auto-correction.'' Alternatively, where means for effecting the correction automatically are available, the operation of the machine may be interrupted to permit visual examination of a rejected card. The card of this invention is also coded for identifying the type of card with respect to its specific function, and whether or not a card is correctly positioned at any predetermined location during its sequential progress through the instrument in which it is evaluated. Dosimeters are evaluated and the card identified in one pass through the instrument. (auth)
Investigation of Forming Performance of Laminated Steel Sheets Using Finite Element Analyses
Liu Wenning; Sun Xin; Ruokolainen, Robert; Gayden Xiaohong
2007-01-01
Laminated steel sheets have been used in automotive structures for reducing in-cabin noise. However, due to the marked difference in material properties of the different laminated layers, integrating laminated steel parts into the manufacturing processes can be challenging. Especially, the behavior of laminated sheets during forming processes is very different from that of monolithic steel sheets. During the deep-draw forming process, large shear deformation and corresponding high interfacial stress may initiate and propagate interfacial cracks between the core polymer and the metal skin, hence degrading the performance of the laminated sheets. In this paper, the formability of the laminated steel sheets is investigated by means of numerical analysis. The goal of this work is to gain insight into the relationship between the individual properties of the laminated sheet layers and the corresponding formability of the laminated sheet as a whole, eventually leading to reliable design and successful forming process development of such materials. Finite element analyses of laminate sheet forming are presented. Effects of polymer core thickness and viscoelastic properties of the polymer core, as well as punching velocity, are also investigated
Design and analysis of reactor containment of steel-concrete composite laminated shell
Ichikawa, K.
1977-01-01
Reinforced and prestressed concrete containments for reactors have been developed in order to avoid the difficulties of welding of steel containments encountered as their capacities have become large: growing thickness of steel shells gave rise to the requirement of stress relief at the construction sites. However, these concrete vessels also seem to face another difficulty: the lack of shearing resistance capacity. In order to improve the shearing resistance capacity of the containment vessel, while avoiding the difficulty of welding, a new scheme of containment consisting of steel-concrete laminated shell is being developed. In the main part of a cylindrical vessel, the shell consists of two layers of thin steel plates located at the inner and outer surfaces, and a layer of concrete core into which both the steel plates are anchored. In order to validate the feasibility and safety of this new design, the results of analysis on the basis of up-to-date design loads are presented. The results of model tests in 1:30 scale are also reported. (Auth.)
Structured cylindrical targets
Arnold, R.
1986-01-01
A variety of experimental concepts using high-energy heavy-ion beams in cylindrical targets have been studied through numerical simulation. With an accelerator planned for GSl, plasma temperatures of 100 eV can be reached by cylindrical compression, using inhomogeneous hollow-shell targets. Magnetic insulation, using external fields, has been explored as an aid in reaching high core temperatures. Experiments on collision-pumped x-ray laser physics are also discussed. (ii) Two-dimensional PlC code simulations of homogeneous solid targets show hydrodynamic effects not found in previous 1-D calculations. (iii) Preliminary ideas for an experiment on non-equilibrium heavy-ion charge-states using an existing accelerator and a pre-formed plasma target are outlined. (author)
Structured cylindrical targets
Arnold, R.; Lackner-Russo, D.; Meyer-ter-Vehn, J.; Hoffmann, I.
1986-01-01
A variety of experimental concepts using high-energy heavy-ion beams in cylindrical targets have been studied through numerical simulation. With an accelerator planned for GSl, plasma temperatures of 100 eV can be reached by cylindrical compression, using inhomogenous hollow-shell targets. Magnetic insulation, using external fields, has been explored as an aid in reaching high core temperatures. Experiments on collision-pumped x-ray laser physics are also discussed. (ii) Two-dimensional PlC code simulations of homogeneous solid targets show hydrodynamic effects not found in previous l-D calculations. (iii) Preliminary ideas for an experiment on non-equilibrium heavy-ion charge-states using an existing accelerator and a pre-formed plasma target are outlined. (author)
"Subclinical" laminitis in dairy cattle.
Vermunt, J J
1992-12-01
In dairying countries worldwide, the economic importance of lameness in cattle is now recognised. Laminitis is regarded as a major predisposing factor in lameness caused by claw disorders such as white zone lesions, sole ulcer, and heel horn erosion. The existence of subclinical laminitis was first suggested in the late 1970s by Dutch workers describing the symptoms of sole haemorrhages and yellowish-coloured, soft sole horn. In an attempt to clarify some of the confusing and often conflicting terminology, the literature on laminitis is reviewed. Disturbed haemodynamics, in particular repeated or prolonged dilation of arteriovenous anastomoses, have been implicated in the pathogenesis of both equine and bovine laminitis. Some characteristics of the vascular system of the bovine claw which may be of importance in the pathophysiology of the subclinical laminitis syndrome are therefore discussed. Clinical observations suggest that subclinical laminitis is a multifactorial disease. The different factors that are or may be involved in its aetiology vary in complexity and severity according to the management protocol of the animals. The possible involvement of subclinical laminitis in claw lesions is assessed.
Continuous jute fibre reinforced laminated paper composite
Jute fibre; laminated paper composite; plastic bag pollution. Abstract. Plastic bags create a serious environmental problem. The proposed jute fibre reinforced laminated paper composite and reinforcement-fibre free paper laminate may help to combat the war against this pollutant to certain extent. The paper laminate ...
Subclinical laminitis in dairy heifers.
Bradley, H K; Shannon, D; Neilson, D R
1989-08-19
By causing poorer horn quality, subclinical laminitis is considered to be a major predisposing cause of other hoof problems, particularly sole ulcers in newly calved heifers. In this study the hind hooves of 136 female Friesian/Holstein cattle aged between four months and two years were examined to discover at what age the signs of subclinical laminitis appeared. Sole haemorrhages were found in the hoof horn of calves as young as five months. The consistent finding of these lesions in heifers of all ages indicated that subclinical laminitis of varying degree was a common condition during the early growing period of young dairy heifers.
Free vibration of fully functionally graded carbon nanotube reinforced graphite/epoxy laminates
Kuo, Shih-Yao
2018-03-01
This study provides the first-known vibration analysis of fully functionally graded carbon nanotube reinforced hybrid composite (FFG-CNTRHC) laminates. CNTs are non-uniformly distributed to reinforce the graphite/epoxy laminates. Some CNT distribution functions in the plane and thickness directions are proposed to more efficiently increase the stiffening effect. The rule of mixtures is modified by considering the non-homogeneous material properties of FFG-CNTRHC laminates. The formulation of the location dependent stiffness matrix and mass matrix is derived. The effects of CNT volume fraction and distribution on the natural frequencies of FFG-CNTRHC laminates are discussed. The results reveal that the FFG layout may significantly increase the natural frequencies of FFG-CNTRHC laminate.
Laskoski, Luciane Maria; Valadão, Carlos Augusto Araújo; Dittrich, Rosangela Locatelli; Deconto, Ivan; Faleiros, Rafael Resende
2016-01-01
ABSTRACT: Laminitis is a severe podal affection, which pathophysiology remains partially renowned. Ischemic, enzymatic, metabolic and inflammatory mechanisms are connected to the development of laminar lesions. However, few therapeutic measures are effective to prevent or control the severity of acute laminitis and its prodromal stage, which often determines serious complications such as rotation and/or sinking of the distal phalanx and even the loss of hoof. The purpose of this study is to c...
Analysis of spring-in in U-shaped composite laminates: Numerical and experimental results
Bellini, Costanzo; Sorrentino, Luca; Polini, Wilma; Parodo, Gianluca
2018-05-01
The phenomena that happen during the cure process of a composite material laminate are responsible for the rise of residual stresses and, consequently, for the deformation at the end of the manufacturing process. The most analyzed deformation is the spring-in, that represent the flange-to-flange angle deviance from the theoretical value. In this work, the influence of some parameters, such as the laminate thickness, the stacking sequence and the mold radius, on the spring-in angle of a U-shaped laminate was studied exploring a full factorial plan through numerical simulations. First of all, a numerical model proper for cure simulation was introduced and its suitability to simulate the deformation behavior was demonstrated. As a result, only the stacking sequence influenced the spring-in value, while the effect of the tool radius and laminate thickness was minimal.
NiCoCrAl/YSZ laminate composites fabricated by EB-PVD
Shi Guodong; Wang Zhi; Liang Jun; Wu Zhanjun
2011-01-01
Highlights: → The metal-ceramic laminate composites were fabricated by EB-PVD. → Both metal and ceramic layers consisted of straight columns with banded structures. → Columnar grain size was limited by the periodic layer interfaces in the laminates. → Effect of columns on fracture property was decreased by limiting layer thickness. → Laminates showed greater specific strength than monolithic metal foil. - Abstract: Two NiCoCrAl/YSZ laminate composites (A and B) with different metal-layer thickness (∼35 μm and 14 μm, respectively) were fabricated by electron beam physical vapor deposition (EB-PVD). Their microstructure was examined and their mechanical properties were compared with the 289 μm thick NiCoCrAl monolithic foil produced by EB-PVD. Both the YSZ and NiCoCrAl layers of the laminate composites had columnar grain structure. But the periodic layer interfaces limited the columnar grain size. Some pores between the columns were also observed. It was found that the strength of the laminate A was equal approximately to that of the NiCoCrAl monolithic foil, and that laminate B had the greater strength. Moreover, the density of the foils decreased with the increasing thickness ratio of YSZ/NiCoCrAl layers and the increasing the layer number. Thus, comparing with the NiCoCrAl monolithic foil, the NiCoCrAl/YSZ laminate composites not only had the equal or greater strength, but also had the much greater specific strength.
Low-energy impact of adaptive cylindrical piezoelectric-composite shells
Saravanos, D.A. [University of Patras (United Kingdom). Dept. of Mechanical Engineering and Aeronautics; Christoforou, A.P. [Kuwait Univ. (Kuwait). Dept. of Mechanical Engineering
2002-04-01
A theoretical framework for analyzing low-energy impacts of laminated shells with active and sensory piezoelectric layers is presented, including impactor dynamics and contact law. The formulation encompasses a coupled piezoelectric shell theory mixing first order shear displacement assumptions and layerwise variation of electric potential. An exact in-plane Ritz solution for the impact of open cylindrical piezoelectric-composite shells is developed and solved numerically using an explicit time integration scheme. The active impact control problem of adaptive cylindrical shells with distributed curved piezoelectric actuators is addressed. The cases of optimized state feedback controllers and output feedback controllers using piezoelectric sensors are analyzed. Numerical results quantify the impact response of cylindrical shells of various curvatures including the signal of curved piezoelectric sensors. Additional numerical studies quantify the impact response of adaptive cylindrical panels and investigate the feasibility of actively reducing the impact force. (author)
On the stabilization of viscoelastic laminated beams with interfacial slip
Mustafa, Muhammad I.
2018-04-01
In this paper, we consider a viscoelastic laminated beam model. This structure is given by two identical uniform layers on top of each other, taking into account that an adhesive of small thickness is bonding the two surfaces and produces an interfacial slip. We use viscoelastic damping with general assumptions on the relaxation function and establish explicit energy decay result from which we can recover the optimal exponential and polynomial rates. Our result generalizes the earlier related results in the literature.
Damage in woven CFRP laminates subjected to low velocity impacts
Ullah, H; Abdel-Wahab, A A; Harland, A R; Silberschmidt, V V
2012-01-01
Carbon fabric-reinforced polymer (CFRP) composites used in sports products can be exposed to different in-service conditions such as large dynamic bending deformations caused by impact loading. Composite materials subjected to such loads demonstrate various damage modes such as matrix cracking, delamination and, ultimately, fabric fracture. Damage evolution in these materials affects both their in-service properties and performance that can deteriorate with time. These processes need adequate means of analysis and investigation, the major approaches being experimental characterisation and non-destructive examination of internal damage in composite laminates. This research deals with a deformation behaviour and damage in woven composite laminates due to low-velocity dynamic out-of-plane bending. Experimental tests are carried out to characterise the behaviour of such laminates under large-deflection dynamic bending in un-notched specimens in Izod tests using a Resil Impactor. A series of low-velocity impact tests is carried out at various levels of impact energy to assess the energy absorbed and force-time response of CFRP laminates. X-ray micro computed tomography (micro-CT) is used to investigate material damage modes in the impacted specimens. X-ray tomographs revealed that through-thickness matrix cracking, inter-ply delamination and intra-ply delamination, such as tow debonding and fabric fracture, were the prominent damage modes.
Static Analysis of Laminated Composite Plate using New Higher Order Shear Deformation Plate Theory
Ibtehal Abbas Sadiq
2017-02-01
Full Text Available In the present work a theoretical analysis depending on the new higher order . element in shear deformation theory for simply supported cross-ply laminated plate is developed. The new displacement field of the middle surface expanded as a combination of exponential and trigonometric function of thickness coordinate with the transverse displacement taken to be constant through the thickness. The governing equations are derived using Hamilton’s principle and solved using Navier solution method to obtain the deflection and stresses under uniform sinusoidal load. The effect of many design parameters such as number of laminates, aspect ratio and thickness ratio on static behavior of the laminated composite plate has been studied. The modal of the present work has been verified by comparing the results of shape functions with that were obtained by other workers. Result shows the good agreement with 3D elasticity solution and that published by other researchers.
The modelling and control of failure in bi-material ceramic laminates
Phillipps, A.J.; Howard, S.J.; Clegg, W.J.; Clyne, T.W.
1993-01-01
Recent experimental and theoretical work on simple, single phase, laminated systems has indicated that failure resistant ceramics can be produced using an elegant method that avoids many of the problems and limitations of comparable fibrous ceramic composites. Theoretical work on these laminated systems has shown good agreement with experiment and simulated the effects of material properties and laminate structure on the composite performance. This work has provided guidelines for optimised laminate performance. In the current study, theoretical work has been simply extended to predict the behaviour of bi-material laminates with alternating layers of weak and strong material with different stiffnesses. Expressions for the strain energy release rates of internal advancing cracks are derived and combined with existing criteria to predict the failure behaviour of these laminates during bending. The modelling indicates three modes of failure dictated by the relative proportions, thicknesses and interfacial properties of the weak and strong phases. A critical percentage of strong phase is necessary to improve failure behaviour, in an identical argument to that for fibre composites. Incorporation of compliant layers is also investigated and implications for laminate design discussed. (orig.)
Binder-free highly conductive graphene laminate for low cost printed radio frequency applications
Huang, Xianjun; Leng, Ting; Zhang, Xiao; Hu, Zhirun, E-mail: Z.Hu@manchester.ac.uk [School of Electrical and Electronic Engineering, University of Manchester, Manchester (United Kingdom); Chen, Jia Cing; Chang, Kuo Hsin [BGT Materials Limited, Photon Science Institute, University of Manchester, Manchester M13 9PL (United Kingdom); Geim, Andre K. [Manchester Centre for Mesoscience and Nanotechnology, University of Manchester, Manchester (United Kingdom); Novoselov, Kostya S. [School of Physics and Astronomy, University of Manchester, Manchester (United Kingdom)
2015-05-18
In this paper, we demonstrate realization of printable radio frequency identification (RFID) antenna by low temperature processing of graphene ink. The required ultra-low resistance is achieved by rolling compression of binder-free graphene laminate. With compression, the conductivity of graphene laminate is increased by more than 50 times compared to that of as-deposited one. Graphene laminate with conductivity of 4.3 × 10{sup 4 }S/m and sheet resistance of 3.8 Ω/sq (with thickness of 6 μm) is presented. Moreover, the formation of graphene laminate from graphene ink reported here is simple and can be carried out in low temperature (100 °C), significantly reducing the fabrication costs. A dipole antenna based on the highly conductive graphene laminate is further patterned and printed on a normal paper to investigate its RF properties. The performance of the graphene laminate antenna is experimentally measured. The measurement results reveal that graphene laminate antenna can provide practically acceptable return loss, gain, bandwidth, and radiation patterns, making it ideal for low cost printed RF applications, such as RFID tags and wearable wireless sensor networks.
Binder-free highly conductive graphene laminate for low cost printed radio frequency applications
Huang, Xianjun; Leng, Ting; Zhang, Xiao; Hu, Zhirun; Chen, Jia Cing; Chang, Kuo Hsin; Geim, Andre K.; Novoselov, Kostya S.
2015-01-01
In this paper, we demonstrate realization of printable radio frequency identification (RFID) antenna by low temperature processing of graphene ink. The required ultra-low resistance is achieved by rolling compression of binder-free graphene laminate. With compression, the conductivity of graphene laminate is increased by more than 50 times compared to that of as-deposited one. Graphene laminate with conductivity of 4.3 × 10 4 S/m and sheet resistance of 3.8 Ω/sq (with thickness of 6 μm) is presented. Moreover, the formation of graphene laminate from graphene ink reported here is simple and can be carried out in low temperature (100 °C), significantly reducing the fabrication costs. A dipole antenna based on the highly conductive graphene laminate is further patterned and printed on a normal paper to investigate its RF properties. The performance of the graphene laminate antenna is experimentally measured. The measurement results reveal that graphene laminate antenna can provide practically acceptable return loss, gain, bandwidth, and radiation patterns, making it ideal for low cost printed RF applications, such as RFID tags and wearable wireless sensor networks
Rotation, inversion and perversion in anisotropic elastic cylindrical tubes and membranes
Goriely, A.
2013-03-06
Cylindrical tubes and membranes are universal structural elements found in biology and engineering over a wide range of scales.Working in the framework of nonlinear elasticity, we consider the possible deformations of elastic cylindrical shells reinforced by one or two families of fibres. We consider both small and large deformations and the reduction from thick cylindrical shells (tubes) to thin shells (cylindrical membranes). In particular, a number of universal parameter regimes can be identified where the response behaviour of the cylinder is qualitatively different. This include the possibility of inversion of twist or axial strain when the cylinder is subject to internal pressure. Copyright © The Royal Society 2013.
Shearfree cylindrical gravitational collapse
Di Prisco, A.; Herrera, L.; MacCallum, M. A. H.; Santos, N. O.
2009-01-01
We consider diagonal cylindrically symmetric metrics, with an interior representing a general nonrotating fluid with anisotropic pressures. An exterior vacuum Einstein-Rosen spacetime is matched to this using Darmois matching conditions. We show that the matching conditions can be explicitly solved for the boundary values of metric components and their derivatives, either for the interior or exterior. Specializing to shearfree interiors, a static exterior can only be matched to a static interior, and the evolution in the nonstatic case is found to be given in general by an elliptic function of time. For a collapsing shearfree isotropic fluid, only a Robertson-Walker dust interior is possible, and we show that all such cases were included in Cocke's discussion. For these metrics, Nolan and Nolan have shown that the matching breaks down before collapse is complete, and Tod and Mena have shown that the spacetime is not asymptotically flat in the sense of Berger, Chrusciel, and Moncrief. The issues about energy that then arise are revisited, and it is shown that the exterior is not in an intrinsic gravitational or superenergy radiative state at the boundary.
Detection of layup errors in prepreg laminates using shear ultrasonic waves
Hsu, David K.; Fischer, Brent A.
1996-11-01
The highly anisotropic elastic properties of the plies in a composite laminate manufactured from unidirectional prepregs interact strongly with the polarization direction of shear ultrasonic waves propagating through its thickness. The received signals in a 'crossed polarizer' transmission configuration are particularly sensitive to ply orientation and layup sequence in a laminate. Such measurements can therefore serve as an NDE tool for detecting layup errors. For example, it was shown experimentally recently that the sensitivity for detecting the presence of misoriented plies is better than one ply out of a 48-ply laminate of graphite epoxy. A physical model based on the decomposition and recombination of the shear polarization vector has been constructed and used in the interpretation and prediction of test results. Since errors should be detected early in the manufacturing process, this work also addresses the inspection of 'green' composite laminates using electromagnetic acoustic transducers (EMAT). Preliminary results for ply error detection obtained with EMAT probes are described.
A Novel Electro-Thermal Laminated Ceramic with Carbon-Based Layer
Yi Ji
2017-06-01
Full Text Available A novel electro-thermal laminated ceramic composed of ceramic tile, carbon-based layer, dielectric layer, and foaming ceramic layer was designed and prepared by tape casting. The surface temperature achieved at an applied voltage of 10 V by the laminated ceramics was 40.3 °C when the thickness of carbon-based suspension was 1.0 mm and the adhesive strength between ceramic tile and carbon-based layer was 1.02 ± 0.06 MPa. In addition, the thermal aging results at 100 °C up to 192 h confirmed the high thermal stability and reliability of the electro-thermal laminated ceramics. The development of this laminated ceramic with excellent electro-thermal properties and safety provides a new individual heating device which is highly expected to be widely applied in the field of indoor heat supply.
Parametric study on patch repaired CFRP laminates using FEA
Kashfuddoja, M.; Ramji, M. [Indian Institute of Technology. Engineering Optics Lab. Dept. of Mechanical Engineering, Hyderabad (India)
2012-07-01
Carbon fibre reinforced plastic (CFRP) composite laminates have become popular for structural applications as they are lighter, stronger and tougher. Composite structures are also susceptible to damage while in service. For improved service life, the damage needs to be repaired so that repair structure integrity is enhanced. Various parameters like patch size and shape, it's layup sequence and adhesive thickness would influence the performance of the repaired structure. In present work, a parametric study is carried out using finite element analysis (FEA) to investigate the influence of various parameters involved in composite repair. The panel is made of carbon / epoxy composite laminate with stacking sequence of (0/{+-}45/900)s and is subjected to tensile load. Damaged CFRP laminates is repaired by symmetrical patch adhesively bonded over the damaged area. Circular patch of different stacking sequence and size is considered. Influence of adhesive material and it's thickness on repair efficiency is also investigated. The influence of various repair parameters on peel stress is also analysed. (Author)
Henrichsen, Søren Randrup; Lindgaard, Esben; Lund, Erik
2015-01-01
Robust buckling optimal design of laminated composite structures is conducted in this work. Optimal designs are obtained by considering geometric imperfections in the optimization procedure. Discrete Material Optimization is applied to obtain optimal laminate designs. The optimal geometric...... imperfection is represented by the “worst” shape imperfection. The two optimization problems are combined through the recurrence optimization. Hereby the imperfection sensitivity of the considered structures can be studied. The recurrence optimization is demonstrated through a U-profile and a cylindrical panel...... example. The imperfection sensitivity of the optimized structure decreases during the recurrence optimization for both examples, hence robust buckling optimal structures are designed....
Optimization of Cylindrical Hall Thrusters
Raitses, Yevgeny; Smirnov, Artem; Granstedt, Erik; Fisch, Nathaniel J.
2007-01-01
The cylindrical Hall thruster features high ionization efficiency, quiet operation, and ion acceleration in a large volume-to-surface ratio channel with performance comparable with the state-of-the-art annular Hall thrusters. These characteristics were demonstrated in low and medium power ranges. Optimization of miniaturized cylindrical thrusters led to performance improvements in the 50-200W input power range, including plume narrowing, increased thruster efficiency, reliable discharge initiation, and stable operation.
Optimization of Cylindrical Hall Thrusters
Raitses, Yevgeny; Smirnov, Artem; Granstedt, Erik; Fi, Nathaniel J.
2007-01-01
The cylindrical Hall thruster features high ionization efficiency, quiet operation, and ion acceleration in a large volume-to-surface ratio channel with performance comparable with the state-of-the-art annular Hall thrusters. These characteristics were demonstrated in low and medium power ranges. Optimization of miniaturized cylindrical thrusters led to performance improvements in the 50-200W input power range, including plume narrowing, increased thruster efficiency, reliable discharge initiation, and stable operation
Baltacioglu, A.K.; Civalek, O.; Akgoez, B.; Demir, F.
2011-01-01
This paper presents nonlinear static analysis of a rectangular laminated composite thick plate resting on nonlinear two-parameter elastic foundation with cubic nonlinearity. The plate formulation is based on first-order shear deformation theory (FSDT). The governing equation of motion for a rectangular laminated composite thick plate is derived by using the von Karman equation. The nonlinear static deflections of laminated plates on elastic foundation are investigated using the discrete singular convolution method. The effects of foundation and geometric parameters of plates on nonlinear deflections are investigated. The validity of the present method is demonstrated by comparing the present results with those available in the literature. - Highlights: → Large deflection analysis of laminated composite plates are investigated. → As foundation, nonlinear elastic models have been used firstly. → The effects of three-parameter foundation are investigated in detail.
Failure modes of laminate structures
Gordon, L.B.; Druce, R.L.; Wilson, M.J.
1987-06-01
Laminate structures composed of alternating thin layers of conductor and dielectric material are commonly used in energy storage and transmission components. The failure of the dielectric layers in regions of high field stress, with applied 60 Hz ac, dc and impulse voltages, was studied. Several geometries were compared, including staggered and flush edges. Electrical trees developed between the laminated dielectric layers. The visual characteristics and growth rates of the electrical trees under ac, dc and impulse stresses were different. Partial discharge detection and analysis was used to measure the inception voltage and discharge activity at the conductor edge voids, to observe tree formation and growth, and to predict impending failure due to dielectric erosion. Electric field distributions were modeled and partial discharge inception levels were estimated from known void geometries. The staggered edge geometry appears to enhance the electric field stress at the recessed electrode.
Optimization of Laminated Composite Structures
Henrichsen, Søren Randrup
of the contributions of the PhD project are included in the second part of the thesis. Paper A presents a framework for free material optimization where commercially available finite element analysis software is used as analysis tool. Robust buckling optimization of laminated composite structures by including...... allows for a higher degree of tailoring of the resulting material. To enable better utilization of the composite materials, optimum design procedures can be used to assist the engineer. This PhD thesis is focused on developing numerical methods for optimization of laminated composite structures...... nonlinear analysis of structures, buckling and post-buckling analysis of structures, and formulations for optimization of structures considering stiffness, buckling, and post-buckling criteria. Lastly, descriptions, main findings, and conclusions of the papers are presented. The papers forming the basis...
Specific contribution of lamin A and lamin C in the development of laminopathies
Sylvius, Nicolas; Hathaway, Andrea; Boudreau, Emilie; Gupta, Pallavi; Labib, Sarah; Bolongo, Pierrette M.; Rippstein, Peter; McBride, Heidi; Bilinska, Zofia T.; Tesson, Frederique
2008-01-01
Mutations in the lamin A/C gene are involved in multiple human disorders for which the pathophysiological mechanisms are partially understood. Conflicting results prevail regarding the organization of lamin A and C mutants within the nuclear envelope (NE) and on the interactions of each lamin to its counterpart. We over-expressed various lamin A and C mutants both independently and together in COS7 cells. When expressed alone, lamin A with cardiac/muscular disorder mutations forms abnormal aggregates inside the NE and not inside the nucleoplasm. Conversely, the equivalent lamin C organizes as intranucleoplasmic aggregates that never connect to the NE as opposed to wild type lamin C. Interestingly, the lamin C molecules present within these aggregates exhibit an abnormal increased mobility. When co-expressed, the complex formed by lamin A/C aggregates in the NE. Lamin A and C mutants for lipodystrophy behave similarly to the wild type. These findings reveal that lamins A and C may be differentially affected depending on the mutation. This results in multiple possible physiological consequences which likely contribute in the phenotypic variability of laminopathies. The inability of lamin C mutants to join the nuclear rim in the absence of lamin A is a potential pathophysiological mechanism for laminopathies
Control and characterization of a bistable laminate generated with piezoelectricity
Lee, Andrew J.; Moosavian, Amin; Inman, Daniel J.
2017-08-01
Extensive research has been conducted on utilizing smart materials such as piezoelectric and shape memory alloy actuators to induce snap through of bistable structures for morphing applications. However, there has only been limited success in initiating snap through from both stable states due to the lack of actuation authority. A novel solution in the form of a piezoelectrically generated bistable laminate consisting of only macro fiber composites (MFC), allowing complete configuration control without any external assistance, is explored in detail here. Specifically, this paper presents the full analytical, computational, and experimental results of the laminate’s design, geometry, bifurcation behavior, and snap through capability. By bonding two actuated MFCs in a [0MFC/90MFC]T layup and releasing the voltage post cure, piezoelectric strain anisotropy and the resulting in-plane residual stresses yield two statically stable states that are cylindrically shaped. The analytical model uses the Rayleigh-Ritz minimization of total potential energy and finite element analysis is implemented in MSC Nastran. The [0MFC/90MFC]T laminate is then manufactured and experimentally characterized for model validation. This paper demonstrates the adaptive laminate’s unassisted forward and reverse snap through capability enabled by the efficiencies gained from simultaneously being the actuator and the primary structure.
Power deposition in a cylindrical geometry using B-10 coatings
Chung, A.K.; Prelas, M.A.
1983-01-01
The transport of charged particles produced by 10 B (n, α) Li and 235 U (n, νn) ff nuclear reactions in a two region cylindrical geometry is predicted. We employed a mean-range straight-flight approximation to calculate the power deposition by the charged particles in a gaseous medium. Our model demonstrated some features in a cylindrical experiment which were suspected but not proven. In the common slab model used by Guyot et al 1 and Romero 2 , the spatial distribution of power deposition is much flatter than it would be in a cylindrical model. A steeper gradient in the power deposition is expected in a cylindrical geometry than in a slab geometry. We also found that for a standard thickness of Boron-10 coating (1.73 μm) used in NPLs, the expected efficiency of a cylindrical geometry (7.5%) is much lower than the 12% efficiency predicted by the slab model. Indeed the use of slab geometry in modeling current NPL experimental devices is not accurate
Impact damages modeling in laminated composite structures
Kreculj Dragan D.
2014-01-01
Full Text Available Laminated composites have an important application in modern engineering structures. They are characterized by extraordinary properties, such as: high strength and stiffness and lightweight. Nevertheless, a serious obstacle to more widespread use of those materials is their sensitivity to the impact loads. Impacts cause initiation and development of certain types of damages. Failures that occur in laminated composite structures can be intralaminar and interlaminar. To date it was developed a lot of simulation models for impact damages analysis in laminates. Those models can replace real and expensive testing in laminated structures with a certain accuracy. By using specialized software the damage parameters and distributions can be determined (at certain conditions on laminate structures. With performing numerical simulation of impact on composite laminates there are corresponding results valid for the analysis of these structures.
Esthetic Rehabilitation of Anterior Teeth with Porcelain Laminates and Sectional Veneers
Gresnigt, Marco; Ozcan, Mutlu
2011-01-01
Full-coverage bonded porcelain restorations offer predictable treatment options in dentistry, but a certain amount of tooth material must be removed to allow space for the required thickness of the restorative material. Laminate veneers and inlays are considered minimally invasive, but they also
Nielsen, Michael Wenani
to their accuracy in predicting process induced strain and stress development in thick section laminates during curing, and more precisely regarding the evolution of the composite thermoset polymer matrix mechanical behaviour during the phase transitions experienced during curing. The different constitutive...
Glucocorticoids and laminitis in the horse.
Johnson, Philip J; Slight, Simon H; Ganjam, Venkataseshu K; Kreeger, John M
2002-08-01
The administration of exogenously administered GCs and syndromes associated with GC excess are both attended by increased risk for the development of laminitis in adult horses. However, there exists substantial controversy as to whether excess GCs cause laminitis de novo. If true, the pathogenesis of laminitis arising from the effects of GC excess is probably different from that associated with diseases of the gastrointestinal tract and endotoxemia. Although a satisfactory explanation for the development of laminitis as a consequence of GC action is currently lacking, numerous possible and plausible theoretical mechanisms do exist. Veterinarians must exert caution with respect to the use of GCs in adult horses. The extent to which individual horses are predisposed to laminitis as a result of GC effect cannot be predicted based on current information. However, the administration of systemic GCs to horses that have been previously affected by laminitis should be used only with extreme caution, and should be accompanied by careful monitoring for further signs of laminitis. The risk of laminitis appears to be greater during treatment using some GCs (especially dexamethasone and triamcinalone) compared with others (prednisone and prednisolone). Whenever possible, to reduce the risk of laminitis, GCs should be administered locally. For example, the risk of GC-associated laminitis is evidently considerably reduced in horses affected with chronic obstructive pulmonary disease (COPD) if GC treatment is administered via inhalation. We have hypothesized that structural changes in the equine hoof that resemble laminitis may arise as a consequence of excess GC effect. Although these changes are not painful per se, and are not associated with inflammation, they could likely predispose affected horses to the development of bona fide laminitis for other reasons. Moreover, the gross morphological appearance of the chronically GC-affected hoof resembles that of a chronically
Embedded adhesive connection for laminated glass plates
Hansen, Jens Zangenberg; Poulsen, S.H.; Bagger, A.
2012-01-01
The structural behavior of a new connection design, the embedded adhesive connection, used for laminated glass plates is investigated. The connection consists of an aluminum plate encapsulated in-between two adjacent triple layered laminated glass plates. Fastening between glass and aluminum...... usage in a design situation. The embedded connection shows promising potential as a future fastening system for load-carrying laminated glass plates....
Cylindrical acoustic levitator/concentrator
Kaduchak, Gregory; Sinha, Dipen N.
2002-01-01
A low-power, inexpensive acoustic apparatus for levitation and/or concentration of aerosols and small liquid/solid samples having particulates up to several millimeters in diameter in air or other fluids is described. It is constructed from a commercially available, hollow cylindrical piezoelectric crystal which has been modified to tune the resonance frequency of the breathing mode resonance of the crystal to that of the interior cavity of the cylinder. When the resonance frequency of the interior cylindrical cavity is matched to the breathing mode resonance of the cylindrical piezoelectric transducer, the acoustic efficiency for establishing a standing wave pattern in the cavity is high. The cylinder does not require accurate alignment of a resonant cavity. Water droplets having diameters greater than 1 mm have been levitated against the force of gravity using; less than 1 W of input electrical power. Concentration of aerosol particles in air is also demonstrated.
Fabrication of laminated Bi-2212/Ag multifilamentary tape
Yuan, D.-W.; Majer, W. J.; Francavilla, T. L.
2000-03-01
The powder-in-tube (PIT) process has been successfully used to make long lengths of Ag-sheathed oxide superconductors. A modified PIT approach is proposed to fabricate conductors with laminated Bi-2212 configurations. Ag/Bi-2212 tapes consisting of seven laminae were produced with various thicknesses ranging from 0.38 to 0.25 mm. The use of a turkshead was found to be beneficial, yielding tapes with good dimensional integrity and consistency. Critical current density (Jc ) values greater than 105 A cm-2 (0.01 T and Bicons/Journals/Common/perp" ALT="perp" ALIGN="TOP"/> tape surface) have been attained for tapes of different thicknesses. Nonetheless, Jc was found to be related to the average thickness of individual Bi-2212 lamina. It is believed that excessive cold working accounts for the decrease in Jc with decreasing size below a threshold value. The enhancement of Jc is attributed to the high Bi-2212 grain alignment along the Ag-oxide interfaces and uniform dimensions within the laminate conductors.
Grammatikos, S.A.; Kordatos, E.Z.; Matikas, T.E.; David, C.; Paipetis, A.S.
2014-01-01
Highlights: • A novel Current injection phase thermography NDE method has been developed. • Blind impact damage has been successfully detected in composite laminates. • Carbon nanotubes enhance detection by improving of through thickness conductivity. • Detection is feasible with considerably less energy than for IR excited thermography. - Abstract: An innovative non-destructive evaluation (NDE) technique is presented based on current stimulated thermography. Modulated electric current is injected to Carbon Fibre Reinforced Plastics (CFRP) laminates as an external source of thermal excitation. Pulsed Phase Thermography (PPT) is concurrently employed to identify low velocity impact induced (LVI) damage. The efficiency of the proposed method is demonstrated for both plain and with Carbon Nanotubes (CNTs) modified laminates, which are subjected to low-velocity impact damaged composite laminates at different energy levels. The presence of the nano reinforcing phase is important in achieving a uniform current flow along the laminate, as it improves the through thickness conductivity. The acquired thermographs are compared with optical PPT, C-scan images and Computer Tomography (CT) representations. The typical energy input for successful damage identification with current injection is three to four orders of magnitude less compared to the energy required for optical PPT
Dost, Ernest F.; Ilcewicz, Larry B.; Avery, William B.; Coxon, Brian R.
1991-01-01
Residual strength of an impacted composite laminate is dependent on details of the damage state. Stacking sequence was varied to judge its effect on damage caused by low-velocity impact. This was done for quasi-isotropic layups of a toughened composite material. Experimental observations on changes in the impact damage state and postimpact compressive performance were presented for seven different laminate stacking sequences. The applicability and limitations of analysis compared to experimental results were also discussed. Postimpact compressive behavior was found to be a strong function of the laminate stacking sequence. This relationship was found to depend on thickness, stacking sequence, size, and location of sublaminates that comprise the impact damage state. The postimpact strength for specimens with a relatively symmetric distribution of damage through the laminate thickness was accurately predicted by models that accounted for sublaminate stability and in-plane stress redistribution. An asymmetric distribution of damage in some laminate stacking sequences tended to alter specimen stability. Geometrically nonlinear finite element analysis was used to predict this behavior.
Development of active CFRP/metal laminates and their demonstrations in complicated forms
Asanuma, H.; Nakata, T.; Tanaka, T.; Imori, M.; Haga, O.
2006-03-01
This paper describes development of high performance CFRP/metal active laminates and demonstrations of them in complicated forms. Various types of the laminates were made by hot-pressing of an aluminum, aluminum alloys, a stainless steel and a titanium for the metal layer as a high CTE material, a unidirectional CFRP prepreg as a low CTE/electric resistance heating material, a unidirectional KFRP prepreg as a low CTE/insulating material. The aluminum and its alloy type laminates have almost the same and the highest room temperature curvatures and they linearly change with increasing temperature up to their fabrication temperature. The curvature of the stainless steel type jumps from one to another around its fabrication temperature, whereas the titanium type causes a double curvature and its change becomes complicated. The output force of the stainless steel type attains the highest of the three under the same thickness. The aluminum type successfully increased its output force by increasing its thickness and using its alloys. The electric resistance of the CFRP layer can be used to monitor the temperature, that is, the curvature of the active laminate because the curvature is a function of temperature. The aluminum type active laminate was made into complicated forms, that is, a hatch, a stack, a coil and a lift types, and their actuation performances were successfully demonstrated.
Telescoping cylindrical piezoelectric fiber composite actuator assemblies
Allison, Sidney G. (Inventor); Shams, Qamar A. (Inventor); Fox, Robert L. (Inventor); Fox, legal representative, Christopher L. (Inventor); Fox Chattin, legal representative, Melanie L. (Inventor)
2010-01-01
A telescoping actuator assembly includes a plurality of cylindrical actuators in a concentric arrangement. Each cylindrical actuator is at least one piezoelectric fiber composite actuator having a plurality of piezoelectric fibers extending parallel to one another and to the concentric arrangement's longitudinal axis. Each cylindrical actuator is coupled to concentrically-adjacent ones of the cylindrical actuators such that the plurality of cylindrical actuators can experience telescopic movement. An electrical energy source coupled to the cylindrical actuators applies actuation energy thereto to generate the telescopic movement.
Filling of charged cylindrical capillaries
Das, Siddhartha; Chanda, Sourayon; Eijkel, J.C.T.; Tas, N.R.; Chakraborty, Suman; Mitra, Sushanta K.
2014-01-01
We provide an analytical model to describe the filling dynamics of horizontal cylindrical capillaries having charged walls. The presence of surface charge leads to two distinct effects: It leads to a retarding electrical force on the liquid column and also causes a reduced viscous drag force because
Optics Demonstrations Using Cylindrical Lenses
Ivanov, Dragia; Nikolov, Stefan
2015-01-01
In this paper we consider the main properties of cylindrical lenses and propose several demonstrational experiments that can be performed with them. Specifically we use simple glasses full of water to demonstrate some basic geometrical optics principles and phenomena. We also present some less standard experiments that can be performed with such…
Dismantling OPAL's cylindrical magnet core
Laurent Guiraud
2001-01-01
Lifting a handling device for dismounting the pressure bells, which are inside the cylindrical magnet coil on the central section of OPAL, on the right part of the photo. OPAL was a detector on the LEP accelerator, which ran from 1989 to 2000.
Cylindrical thin-shell wormholes
Eiroa, Ernesto F.; Simeone, Claudio
2004-01-01
A general formalism for the dynamics of nonrotating cylindrical thin-shell wormholes is developed. The time evolution of the throat is explicitly obtained for thin-shell wormholes whose metric has the form associated with local cosmic strings. It is found that the throat collapses to zero radius, remains static, or expands forever, depending only on the sign of its initial velocity
Convolute laminations — a theoretical analysis: example of a Pennsylvanian sandstone
Visher, Glenn S.; Cunningham, Russ D.
1981-03-01
Data from an outcropping laminated interval were collected and analyzed to test the applicability of a theoretical model describing instability of layered systems. Rayleigh—Taylor wave perturbations result at the interface between fluids of contrasting density, viscosity, and thickness. In the special case where reverse density and viscosity interlaminations are developed, the deformation response produces a single wave with predictable amplitudes, wavelengths, and amplification rates. Physical measurements from both the outcropping section and modern sediments suggest the usefulness of the model for the interpretation of convolute laminations. Internal characteristics of the stratigraphic interval, and the developmental sequence of convoluted beds, are used to document the developmental history of these structures.
... in individuals with nail fungus (onychomycosis), psoriasis and hypothyroidism. Those who have problems with the thickness of their toenails should consult a foot and ankle surgeon for proper diagnosis and treatment. Find an ACFAS Physician Search Search Tools Find ...
Schilf, Paul; Peter, Annette; Hurek, Thomas; Stick, Reimer
2014-07-01
Lamin proteins are found in all metazoans. Most non-vertebrate genomes including those of the closest relatives of vertebrates, the cephalochordates and tunicates, encode only a single lamin. In teleosts and tetrapods the number of lamin genes has quadrupled. They can be divided into four sub-types, lmnb1, lmnb2, LIII, and lmna, each characterized by particular features and functional differentiations. Little is known when during vertebrate evolution these features have emerged. Lampreys belong to the Agnatha, the sister group of the Gnathostomata. They split off first within the vertebrate lineage. Analysis of the sea lamprey (Petromyzon marinus) lamin complement presented here, identified three functional lamin genes, one encoding a lamin LIII, indicating that the characteristic gene structure of this subtype had been established prior to the agnathan/gnathostome split. Two other genes encode lamins for which orthology to gnathostome lamins cannot be designated. Search for lamin gene sequences in all vertebrate taxa for which sufficient sequence data are available reveals the evolutionary time frame in which specific features of the vertebrate lamins were established. Structural features characteristic for A-type lamins are not found in the lamprey genome. In contrast, lmna genes are present in all gnathostome lineages suggesting that this gene evolved with the emergence of the gnathostomes. The analysis of lamin gene neighborhoods reveals noticeable similarities between the different vertebrate lamin genes supporting the hypothesis that they emerged due to two rounds of whole genome duplication and makes clear that an orthologous relationship between a particular vertebrate paralog and lamins outside the vertebrate lineage cannot be established. Copyright © 2014 Elsevier GmbH. All rights reserved.
Wettability of graphene-laminated micropillar structures
Bong, Jihye; Seo, Keumyoung; Ju, Sanghyun; Park, Ji-Hoon; Ahn, Joung Real
2014-01-01
The wetting control of graphene is of great interest for electronic, mechanical, architectural, and bionic applications. In this study, the wettability of graphene-laminated micropillar structures was manipulated by changing the height of graphene-laminated structures and employing the trichlorosilane (HDF-S)-based self-assembly monolayer. Graphene-laminated micropillar structures with HDF-S exhibited higher hydrophobicity (contact angle of 129.5°) than pristine graphene thin film (78.8°), pristine graphene-laminated micropillar structures (97.5°), and HDF-S self-assembled graphene thin film (98.5°). Wetting states of the graphene-laminated micropillar structure with HDF-S was also examined by using a urea solution, which flowed across the surface without leaving any residues
Homotheties of cylindrically symmetric static spacetimes
Qadir, A.; Ziad, M.; Sharif, M.
1998-08-01
In this note we consider the homotheties of cylindrically symmetric static spacetimes. We find that we can provide a complete list of all metrics that admit non-trivial homothetic motions and are cylindrically symmetric static. (author)
Ceramic laminates with tailored residual stresses
Baudín, C.
2009-12-01
Full Text Available Severe environments imposed by new technologies demand new materials with better properties and ensured reliability. The intrinsic brittleness of ceramics has forced scientists to look for new materials and processing routes to improve the mechanical behaviour of ceramics in order to allow their use under severe thermomechanical conditions. The laminate approach has allowed the fabrication of a new family of composite materials with strength and reliability superior to those of monolithic ceramics with microstructures similar to those of the constituent layers. The different ceramic laminates developed since the middle 1970´s can be divided in two large groups depending on whether the development of residual stresses between layers is the main design tool. This paper reviews the developments in the control and tailoring of residual stresses in ceramic laminates. The tailoring of the thickness and location of layers in compression can lead to extremely performing structures in terms of strength values and reliability. External layers in compression lead to the strengthening of the structure. When relatively thin and highly compressed layers are located inside the material, threshold strength, crack bifurcation and crack arrest during fracture occur.
Las severas condiciones de trabajo de las nuevas aplicaciones tecnológicas exigen el uso de materiales con mejores propiedades y alta fiabilidad. La potencialidad de uso de materiales frágiles, como los cerámicos, en estas aplicaciones exige el desarrollo de nuevos materiales y métodos de procesamiento que mejoren su comportamiento mecánico. El concepto de material laminado ha permitido la fabricación de una nueva familia de materiales con tensiones de fractura y fiabilidad superiores a las de materiales monolíticos con microestructuras similares a las de las láminas que conforman el laminado. Los distintos materiales laminados desarrollados desde mediados de los años 70 se pueden
Irradiating rubber laminate containing sensitive agent in layer
Bohm, G.G.A.
1979-01-01
Rubber compounds may be sensitized to cure or partially cure when subjected to irradiation. If certain layers of a rubber laminate are treated with sensitizing materials and other layers wth densensitizing materials a composite is produced having cured and uncured layers after it has been subjected to irradiation. This technique enables the production of composite laminates in which predetermined layers have predetermined physical characteristics which are desirable in the manufacture of the ultimate end product, for example, automotive tires. Several chemicals have been found to accelerate the cure of rubber compounds by irradiation and several have been found which inhibit the cure. Paradichlorobenzene (PDCB) and certain of the thioetherpolythiols are effective cure promotors. Effective retarders include aromatic oils, sulfur, sulfur cure accelerators and some rubber antioxidants and/or antiozonants of the substituted diphenylamine type. The dosage of irradiation is dependent upon several variables: the type of rubber, the promotor or retarder utilized, the level of the promotor or retarder, the thickness of the layer of material, the thickness of adjacent layers of materials, the sequence of the layers of material, the number of the layers of material and whether the irradiation is applied to one or both sides of the composite strip. The dosage may be controlled by the amount of energy employed so that the electrons do not completely penetrate the entire strip. This results in the irradiaton of part of the strip, but not the entire strip. (LL)
Design and Manufacture of Conical Shell Structures Using Prepreg Laminates
Khakimova, Regina; Burau, Florian; Degenhardt, Richard; Siebert, Mark; Castro, Saullo G. P.
2016-06-01
The design and manufacture of unstiffened composite conical structures is very challenging, as the variation of the fiber orientations, lay-up and the geometry of the ply pieces have a significant influence on the thickness imperfections and ply angle deviations imprinted to the final part. This paper deals with the manufacture of laminated composite cones through the prepeg/autoclave process. The cones are designed to undergo repetitive buckling tests without accumulating permanent damage. The aim is to define a process that allows the control of fiber angle deviations and the removal of thickness imperfections generated from gaps and overlaps between ply pieces. Ultrasonic scan measurements are used to proof the effectiveness of the proposed method.
Master plot analysis of microcracking in graphite/epoxy and graphite/PEEK laminates
Nairn, John A.; Hu, Shoufeng; Bark, Jong Song
1993-01-01
We used a variational stress analysis and an energy release rate failure criterion to construct a master plot analysis of matrix microcracking. In the master plot, the results for all laminates of a single material are predicted to fall on a single line whose slope gives the microcracking toughness of the material. Experimental results from 18 different layups of AS4/3501-6 laminates show that the master plot analysis can explain all observations. In particular, it can explain the differences between microcracking of central 90 deg plies and of free-surface 90 deg plies. Experimental results from two different AS4/PEEK laminates tested at different temperatures can be explained by a modified master plot that accounts for changes in the residual thermal stresses. Finally, we constructed similar master plot analyses for previous literature microcracking models. All microcracking theories that ignore the thickness dependence of the stresses gave poor results.
Third-order polynomial model for analyzing stickup state laminated structure in flexible electronics
Meng, Xianhong; Wang, Zihao; Liu, Boya; Wang, Shuodao
2018-02-01
Laminated hard-soft integrated structures play a significant role in the fabrication and development of flexible electronics devices. Flexible electronics have advantageous characteristics such as soft and light-weight, can be folded, twisted, flipped inside-out, or be pasted onto other surfaces of arbitrary shapes. In this paper, an analytical model is presented to study the mechanics of laminated hard-soft structures in flexible electronics under a stickup state. Third-order polynomials are used to describe the displacement field, and the principle of virtual work is adopted to derive the governing equations and boundary conditions. The normal strain and the shear stress along the thickness direction in the bi-material region are obtained analytically, which agree well with the results from finite element analysis. The analytical model can be used to analyze stickup state laminated structures, and can serve as a valuable reference for the failure prediction and optimal design of flexible electronics in the future.
Eye and sheath folds in turbidite convolute lamination: Aberystwyth Grits Group, Wales
McClelland, H. L. O.; Woodcock, N. H.; Gladstone, C.
2011-07-01
Eye and sheath folds are described from the turbidites of the Aberystwyth Group, in the Silurian of west Wales. They have been studied at outcrop and on high resolution optical scans of cut surfaces. The folds are not tectonic in origin. They occur as part of the convolute-laminated interval of each sand-mud turbidite bed. The thickness of this interval is most commonly between 20 and 100 mm. Lamination patterns confirm previous interpretations that convolute lamination nucleated on ripples and grew during continued sedimentation of the bed. The folds amplified vertically and were sheared horizontally by continuing turbidity flow, but only to average values of about γ = 1. The strongly curvilinear fold hinges are due not to high shear strains, but to nucleation on sinuous or linguoid ripples. The Aberystwyth Group structures provide a warning that not all eye folds in sedimentary or metasedimentary rocks should be interpreted as sections through high shear strain sheath folds.
Cylindrical collapse and gravitational waves
Herrera, L [Escuela de FIsica, Faculdad de Ciencias, Universidad Central de Venezuela, Caracas, Venezuela (Venezuela); Santos, N O [Universite Pierre et Marie Curie, CNRS/FRE 2460 LERMA/ERGA, Tour 22-12, 4eme etage, BoIte 142, 4 place Jussieu, 75252 Paris Cedex 05 (France); Laboratorio Nacional de Computacao Cientifica, 25651-070 Petropolis RJ (Brazil); Centro Brasileiro de Pesquisas Fisicas, 22290-180 Rio de Janeiro RJ (Brazil)
2005-06-21
We study the matching conditions for a collapsing anisotropic cylindrical perfect fluid, and we show that its radial pressure is non-zero on the surface of the cylinder and proportional to the time-dependent part of the field produced by the collapsing fluid. This result resembles the one that arises for the radiation-though non-gravitational-in the spherically symmetric collapsing dissipative fluid, in the diffusion approximation.
Cracking of anisotropic cylindrical polytropes
Mardan, S.A. [University of the Management and Technology, Department of Mathematics, Lahore (Pakistan); Azam, M. [University of Education, Division of Science and Technology, Lahore (Pakistan)
2017-06-15
We study the appearance of cracking in charged anisotropic cylindrical polytropes with generalized polytropic equation. We investigate the existence of cracking in two different kinds of polytropes existing in the literature through two different assumptions: (a) local density perturbation with conformally flat condition, and (b) perturbing polytropic index, charge and anisotropy parameters. We conclude that cracking appears in both kinds of polytropes for a specific range of density and model parameters. (orig.)
Cylindrical Piezoelectric Fiber Composite Actuators
Allison, Sidney G.; Shams, Qamar A.; Fox, Robert L.
2008-01-01
The use of piezoelectric devices has become widespread since Pierre and Jacques Curie discovered the piezoelectric effect in 1880. Examples of current applications of piezoelectric devices include ultrasonic transducers, micro-positioning devices, buzzers, strain sensors, and clocks. The invention of such lightweight, relatively inexpensive piezoceramic-fiber-composite actuators as macro fiber composite (MFC) actuators has made it possible to obtain strains and displacements greater than those that could be generated by prior actuators based on monolithic piezoceramic sheet materials. MFC actuators are flat, flexible actuators designed for bonding to structures to apply or detect strains. Bonding multiple layers of MFC actuators together could increase force capability, but not strain or displacement capability. Cylindrical piezoelectric fiber composite (CPFC) actuators have been invented as alternatives to MFC actuators for applications in which greater forces and/or strains or displacements may be required. In essence, a CPFC actuator is an MFC or other piezoceramic fiber composite actuator fabricated in a cylindrical instead of its conventional flat shape. Cylindrical is used here in the general sense, encompassing shapes that can have circular, elliptical, rectangular or other cross-sectional shapes in the planes perpendicular to their longitudinal axes.
Predisposing factors of laminitis in cattle.
Vermunt, J J; Greenough, P R
1994-01-01
Laminitis is regarded as a major predisposing factor in lameness caused by claw disorders. Despite intensive study, both by experiment and by clinical observation, knowledge of the precise aetiology and pathogenesis of bovine laminitis is still incomplete. It is often hypothesized that changes in the micro-circulation of the corum (dermis) of the bovine claw contribute significantly to the development of laminitis; arteriovenous anastomoses (AVAs) playing a crucial role. Many factors have been implicated as contributing causes of laminitis in cattle; the disease has a multifactorial aetiology. The cause of laminitis should be considered as a combination of predisposing factors leading to vascular (AVAs in particular) reactivity and inhibition of normal horn synthesis. Nutrition, disease, management and behaviour appear to be closely involved in the pathogenesis of bovine laminitis. The major factors predisposing to laminitis in cattle, as reported or suggested in the literature, are reviewed, including systemic disease, nutrition (barley grain, protein, carbohydrate and fibre), management (housing, bedding and exercise), calving, season, age, growth, genetics, conformation and behaviour.
Laminitis and the equine metabolic syndrome.
Johnson, Philip J; Wiedmeyer, Charles E; LaCarrubba, Alison; Ganjam, V K Seshu; Messer, Nat T
2010-08-01
Although much has been written about laminitis in the context of its association with inflammatory processes, recognition is growing that most cases of laminitis examined by veterinarians in private practice are those associated with pasture grazing, obesity, and insulin resistance (IR). The term 'endocrinopathic laminitis' has been adopted to classify the instances of laminitis in which the origin seems to be more strongly associated with an underlying endocrinopathy, such as either IR or the influence of corticosteroids. Results of a recent study suggest that obesity and IR represent the most common metabolic and endocrinopathic predispositions for laminitis in horses. IR also plays an important role in the pathogenesis of laminitis that develops when some horses or ponies are allowed to graze pastures at certain times of the year. The term equine metabolic syndrome (EMS) has been proposed as a label for horses whose clinical examination results (including both physical examination and laboratory testing) suggest heightened risk for developing laminitis as a result of underlying IR. Copyright (c) 2010 Elsevier Inc. All rights reserved.
Meshfree modeling in laminated composites
Simkins, Daniel Craig; Collier, Nathan; Alford, Joseph B.
2012-01-01
A problem of increasing importance in the aerospace industry is in detailed modeling of explicit fracture in laminated composite materials. For design applications, the simulation must be capable of initiation and propagation of changes in the problem domain. Further, these changes must be able to be incorporated within a design-scale simulation. The use of a visibility condition, coupled with the local and dynamic nature of meshfree shape function construction allows one to initiate and explicitly open and propagate holes inside a previously continuous problem domain. The method to be presented naturally couples to a hierarchical multi-scale material model incorporating external knowldege bases to achieve the goal of a practical explicit fracture modeling capability for full-scale problems. © 2013 Springer-Verlag.
Meshfree modeling in laminated composites
Simkins, Daniel Craig
2012-09-27
A problem of increasing importance in the aerospace industry is in detailed modeling of explicit fracture in laminated composite materials. For design applications, the simulation must be capable of initiation and propagation of changes in the problem domain. Further, these changes must be able to be incorporated within a design-scale simulation. The use of a visibility condition, coupled with the local and dynamic nature of meshfree shape function construction allows one to initiate and explicitly open and propagate holes inside a previously continuous problem domain. The method to be presented naturally couples to a hierarchical multi-scale material model incorporating external knowldege bases to achieve the goal of a practical explicit fracture modeling capability for full-scale problems. © 2013 Springer-Verlag.
Sun, Yao; Yang, Tiejun; Chen, Yuehua
2018-06-01
In this paper, sound radiation modes of baffled cylinders have been derived by constructing the radiation resistance matrix analytically. By examining the characteristics of sound radiation modes, it is found that radiation coefficient of each radiation mode increases gradually with the increase of frequency while modal shapes of sound radiation modes of cylindrical shells show a weak dependence upon frequency. Based on understandings on sound radiation modes, vibro-acoustics behaviors of cylindrical shells have been analyzed. The vibration responses of cylindrical shells are described by modified Fourier series expansions and solved by Rayleigh-Ritz method involving Flügge shell theory. Then radiation efficiency of a resonance has been determined by examining whether the vibration pattern is in correspondence with a sound radiation mode possessing great radiation efficiency. Furthermore, effects of thickness and boundary conditions on sound radiation of cylindrical shells have been investigated. It is found that radiation efficiency of thicker shells is greater than thinner shells while shells with a clamped boundary constraint radiate sound more efficiently than simply supported shells under thin shell assumption.
Design of a cylindrical LED substrate without radiator
Tang, Fan; Guo, Zhenning
2017-12-01
To reduce the weight and production costs of light-emitting diode (LED) lamps, we applied the principle of the chimney effect to design a cylindrical LED substrate without a radiator. We built a 3D model by using Solidworks software and applied the flow simulation plug-in to conduct model simulation, thereby optimizing the heat source distribution and substrate thickness. The results indicate that the design achieved optimal cooling with a substrate with an upper extension length of 35 mm, a lower extension length of 8 mm, and a thickness of 1 mm. For a substrate of those dimensions, the highest LED chip temperature was 64.78 °C, the weight of the substrate was 35.09 g, and R jb = 7.00 K/W. If the substrate is powered at 8, 10, and 12 W, its temperature meets LED safety requirements. In physical tests, the highest temperature for a physical 8 W cylindrical LED substrate was 66 °C, which differed by only 1.22 °C from the simulation results, verifying the validity of the simulation. The designed cylindrical LED substrate can be used in high-power LED lamps that do not require radiators. This design is not only excellent for heat dissipation, but also for its low weight, low cost, and simplicity of manufacture.
Masking ability of bi- and tri- laminate all-ceramic veneers on tooth-colored ceramic discs.
Farhan, Daniel; Sukumar, Smitha; von Stein-Lausnitz, Axel; Aarabi, Ghazal; Alawneh, Ahmad; Reissmann, Daniel R
2014-01-01
A predictable esthetic outcome is imperative when placing ceramic veneers. Discolored teeth pose a major challenge as sufficient material thickness is required to achieve a good esthetic result. There is limited evidence in the literature that compares the masking ability of multi-laminate veneers. The aim of this in-vitro study was to compare the masking ability of bi-laminate (BL) and tri-laminate (TL) all-ceramic veneers cemented on tooth-colored ceramic discs. A total of 40 veneers (shade A1, 10-mm diameter, 0.8-mm thick) were manufactured-20 BL veneers (0.4-mm pressable ceramic coping veneered with 0.4-mm thick enamel layer) and 20 TL veneers (0.4-mm coping veneered with 0.2-mm thick opaque interlayer and 0.2-mm thick enamel layer). A bonding apparatus was utilized to adhesively cement all veneers on the ceramic discs (shade A1), simulating teeth of light and dark color. The resulting groups (N = 10 each) were the reference groups (shade A1 ceramic base) BL-1 and TL-1 veneers, and the test groups (shade A4 ceramic base) BL-4 and TL-4 veneers. The color of the cemented veneers was measured using a spectrophotometer. The data were converted to CIE L*a*b* coordinates, and ΔE* were calculated to allow for statistical analysis. The color differences between the samples with the A1 and A4 ceramic bases were significantly lower when covered with TL veneers (mean ΔE*: 3.2 units) than with BL veneers (mean ΔE*: 4.0 units: p bi-laminate veneers. Patients with discolored/darker teeth may benefit from a more predictable esthetic result when teeth restored with tri-laminate rather than bi-laminate veneers. © 2014 Wiley Periodicals, Inc.
Bautista, Zhierwinjay M.; Shin, Hyung Seop [Dept. of Mechanical Design Engineering, Andong National University, Andong (Korea, Republic of); Lee, Jae Hun; Lee, Hun Ju; Moon, Seung Hyun [SuNAM Co Ltd., Anseong (Korea, Republic of)
2016-09-15
The enhancement of mechanical properties of coated conductor (CC) tapes in practical application are usually achieved by reinforcing through lamination or electroplating metal layers on either sides of the CC tape. Mechanical or electromechanical properties of the CC tapes have been largely affected by the lamination structure under various loading modes such as tension, bending or even cyclic. In this study, the influence of brass laminate volume fraction on electromechanical properties of RCE-DR processed Gadolinium-barium-copper-oxide (GdBCO) CC tapes was investigated. The samples used were composed of single-side and both-side laminate of brass layer to the Cu-stabilized CC tape and their Ic behaviors were compared to those of the Cu-stabilized CC tape without external lamination. The stress/strain dependences of Ic in laminated CC tapes under uniaxial tension were analyzed and the irreversible stress/strain limits were determined. As a result, the increase of brass laminate volume fraction initially increased the irreversible strain limit and became gradual. The corresponding irreversible stress limit, however, showed no difference even though the brass laminate volume fraction increased to 3.4. But the irreversible load limit linearly increased with the brass laminate volume fraction.
Laminate mechanics for balanced woven fabrics
Akkerman, Remko
2006-01-01
Laminate mechanics equations are presented for composites with balanced woven fabric reinforcements. It is shown that mimicking these textile composites with equivalent transversely isotropic (‘unidirectional’) layers requires disputable manipulations. Various micromechanics predictions of textile
Natural fabric sandwich laminate composites: development and ...
3Department of Production Technology, MIT Campus, Anna University, Chennai 600044, India. MS received ... In this work, eco-friendly natural fabric sandwich laminate (NFSL) composites are formulated using ... and eco-friendly quality [22].
Behaviour of Mechanically Laminated CLT Members
Kuklík, P.; Velebil, L.
2015-11-01
Cross laminated timber (CLT) is one of the structural building systems based on the lamination of multiple layers, where each layer is oriented perpendicularly to each other. Recent requirements are placed to develop an alternative process based on the mechanical lamination of the layers, which is of particular interest to our research group at the University Centre for Energy Efficient Buildings. The goal is to develop and verify the behaviour of mechanically laminated CLT wall panels exposed to shear stresses in the plane. The shear resistance of mechanically jointed CLT is ensured by connecting the layers by screws. The paper deals with the experimental analysis focused on the determination of the torsional stiffness and the slip modulus of crossing areas for different numbers of orthogonally connected layers. The results of the experiments were compared with the current analytical model.
Absorption factor for cylindrical samples
Sears, V.F.
1984-01-01
The absorption factor for the scattering of X-rays or neutrons in cylindrical samples is calculated by numerical integration for the case in which the absorption coefficients of the incident and scattered beams are not equal. An extensive table of values having an absolute accuracy of 10 -4 is given in a companion report [Sears (1983). Atomic Energy of Canada Limited, Report No. AECL-8176]. In the present paper an asymptotic expression is derived for the absorption factor which can be used with an error of less than 10 -3 for most cases of interest in both neutron inelastic scattering and neutron diffraction in crystals. (Auth.)
Peloso, J.G.; Cohen, N.D.; Walker, M.A.; Watkins, J.P.; Gayle, J.M.; Moyer, W.
1996-01-01
To identify risk factors associated with development of laminitis of the supporting limb in Equidae with unilateral laminitis and to determine the radiographic appearance of this type of laminitis. Retrospective analysis of medical records. 20 Equidae with unilateral lameness that developed laminitis of the contralateral limb. Case animals were compared with matched and unmatched populations of control animals that did not develop contralateral limb laminitis. Lateromedial radiographic projections of affected feet were evaluated for evidence of laminitis. Body weight of case animals was not significantly different from that of control animals, but number of days that control animals were lame prior to recovery was significantly less than number of days that case animals were lame prior to the onset of laminitis. Lateromedial radiographic projections of the foot of the support limb were available for 16 of the 20 case animals. For all 16, thickness of the soft tissue dorsal to the distal phalanx was > 29% of the palmar cortical length of the distal phalanx, but only 1 had evidence of rotation of the distal phalanx. The proportion of case animals that were euthanatized was significantly greater than the proportion of control animals that were euthanatized. Duration of lameness, but not body weight, was a risk factor for development of laminitis in the contralateral limb in Equidae with unilateral lameness, and animals that developed this complication were more likely to be euthanatized than were animals that did not
Herwan, J.
2014-11-01
© Institute of Materials, Minerals and Mining 2014. Mode II delamination properties of Vectran stitched composites were investigated, and tabbed end notch flexural specimen testing was used to prevent premature failure. The effects of stitch density and stitch thread thickness were explored, and fibre compaction due to the stitching process was also verified. The results show that, in moderately stitched laminates (low stitch density), the improvement in GIIC was negligible. Crack bridging by the stitch threads at the crack zone were mostly compensated for the effect of fibre compaction, which reduced the GIIC values. Conversely, in densely stitched laminates (high stitch density), GIIC values were improved significantly (2·4 times higher than those of unstitched laminates). The effects of stitch thread thickness appeared to be negligible in moderately stitched laminates. For densely stitched laminates, thicker stitch thread (500 denier) possessed GIIC values that were 45·7% higher than thinner stitch thread (200 denier).
Herwan, J.; Kondo, A.; Morooka, S.; Watanabe, N.
2014-01-01
© Institute of Materials, Minerals and Mining 2014. Mode II delamination properties of Vectran stitched composites were investigated, and tabbed end notch flexural specimen testing was used to prevent premature failure. The effects of stitch density and stitch thread thickness were explored, and fibre compaction due to the stitching process was also verified. The results show that, in moderately stitched laminates (low stitch density), the improvement in GIIC was negligible. Crack bridging by the stitch threads at the crack zone were mostly compensated for the effect of fibre compaction, which reduced the GIIC values. Conversely, in densely stitched laminates (high stitch density), GIIC values were improved significantly (2·4 times higher than those of unstitched laminates). The effects of stitch thread thickness appeared to be negligible in moderately stitched laminates. For densely stitched laminates, thicker stitch thread (500 denier) possessed GIIC values that were 45·7% higher than thinner stitch thread (200 denier).
Temperature distribution of thick thermoset composites
Guo, Zhan-Sheng; Du, Shanyi; Zhang, Boming
2004-05-01
The development of temperature distribution of thick polymeric matrix laminates during an autoclave vacuum bag process was measured and compared with numerically calculated results. The finite element formulation of the transient heat transfer problem was carried out for polymeric matrix composite materials from the heat transfer differential equations including internal heat generation produced by exothermic chemical reactions. Software based on the general finite element software package was developed for numerical simulation of the entire composite process. From the experimental and numerical results, it was found that the measured temperature profiles were in good agreement with the numerical ones, and conventional cure cycles recommended by prepreg manufacturers for thin laminates should be modified to prevent temperature overshoot.
Sensitivity study of buckling strength for cylindrical shells
Kato, Hideo; Sasaki, Toru [Institute of Nuclear Safety System Inc., Mihama, Fukui (Japan)
2001-09-01
Aiming at making clear buckling behavior of cylindrical shells under earthquake loadings, we investigated procedure of recent elastic-plastic buckling analysis by finite element method (FEM). Thereby it is confirmed that the buckling strength becomes as well as that of a shell with a cross section of a perfect cylinder, if we apply the first buckling eigenvector to imperfection mode and assume the maximum imperfection amplitude to be 1% of the wall thickness. And then, by carrying out sensitivity study of buckling with geometrical parameters, such as length (L), radius (R), wall thickness (t), and load parameter, such as pressure, we obtained several characteristics about buckling strength and buckling mode for cylindrical shells. From the geometrical parameter analysis, it is seen that bending buckling occurs for small R/t (thick wall) and elastic buckling occurs for 2{<=}L/R{<=}4 and R/t{>=}400. And from the load parameter analysis, it is shown that hoop stress caused by the inner pressure increases shear buckling strength but decreases bending buckling strength, and hoop stress by hydrostatic pressure changes buckling mode and generates local deformation. (author)
Scarf Repair of Composite Laminates
Xie Zonghong
2016-01-01
Full Text Available The use of composite materials, such as carbon-fiber reinforced plastic (CFRP composites, aero-structures has led to an increased need of advanced assembly joining and repair technologies. Adhesive bonded repairs as an alternative to recover full or part of initial strength were investigated. Tests were conducted with the objective of evaluating the effectiveness of techniques used for repairing damage fiber reinforced laminated composites. Failure loads and failure modes were generated and compared with the following parameters: scarf angles, roughness of grind tool and number of external plies. Results showed that scarf angle was the critical parameter and the largest tensile strength was observed with the smallest scarf angle. Besides, the use of external plies at the outer surface could not increase the repairs efficiency for large scarf angle. Preparing the repair surfaces by sanding them with a sander ranging from 60 to 100 grit number had significant effect on the failure load. These results allowed the proposal of design principles for repairing CFRP structures.
Cohesive Modeling of Transverse Cracking in Laminates with a Single Layer of Elements per Ply
VanDerMeer, Frans P.; Davila, Carlos G.
2013-01-01
This study aims to bridge the gap between classical understanding of transverse cracking in cross-ply laminates and recent computational methods for the modeling of progressive laminate failure. Specifically, the study investigates under what conditions a finite element model with cohesive X-FEM cracks can reproduce the in situ effect for the ply strength. It is shown that it is possible to do so with a single element across the thickness of the ply, provided that the interface stiffness is properly selected. The optimal value for this interface stiffness is derived with an analytical shear lag model. It is also shown that, when the appropriate statistical variation of properties has been applied, models with a single element through the thickness of a ply can predict the density of transverse matrix cracks
A paper sheet phantom for scintigraphic planar imaging. Usefulness of pouch-laminated paper source
Takaki, Akihiro; Soma, Tsutomu; Murase, Kenya; Teraoka, Satomi; Murakami, Tomonori; Kojima, Akihiro; Matsumoto, Masanori
2007-01-01
In order to perform experimental measurements for evaluation of imaging device's performance, data acquisition technique, and clinical images on scintigraphic imaging, many kinds of phantoms are employed. However, since these materials are acrylic and plastic, the thickness and quality of those materials cause attenuation and scatter in itself. We developed a paper sheet phantom sealed with a pouch laminator, which can be a true radioactive source in air. In this study, the paper sheet phantom was compared to the acrylic liver phantom, with the thickness of 2 cm, which is commercially available. The results showed that although some scatter counts were contained within the image of the acrylic liver phantom, there were few scattered photons in the paper sheet phantom image. Furthermore, this laminated paper sheet phantom made handling of the source and its waste easier. If the paper sheet phantom will be designed more sophisticatedly, it becomes a useful tool for planar imaging experiments. (author)
Thermal flexural analysis of cross-ply laminated plates using trigonometric shear deformation theory
Yuwaraj Marotrao Ghugal
Full Text Available Thermal stresses and displacements for orthotropic, two-layer antisymmetric, and three-layer symmetric square cross-ply laminated plates subjected to nonlinear thermal load through the thickness of laminated plates are presented by using trigonometric shear deformation theory. The in-plane displacement field uses sinusoidal function in terms of thickness co-ordinate to include the shear deformation effect. The theory satisfies the shear stress free boundary conditions on the top and bottom surfaces of the plate. The present theory obviates the need of shear correction factor. Governing equations and boundary conditions of the theory are obtained using the principle of virtual work. The validity of present theory is verified by comparing the results with those of classical plate theory and first order shear deformation theory and higher order shear deformation theory.
Zhamu, Aruna; Shi, Jinjun; Guo, Jiusheng; Jang, Bor Z
2014-05-20
An electrically conductive laminate composition for fuel cell flow field plate or bipolar plate applications. The laminate composition comprises at least a thin metal sheet having two opposed exterior surfaces and a first exfoliated graphite composite sheet bonded to the first of the two exterior surfaces of the metal sheet wherein the exfoliated graphite composite sheet comprises: (a) expanded or exfoliated graphite and (b) a binder or matrix material to bond the expanded graphite for forming a cohered sheet, wherein the binder or matrix material is between 3% and 60% by weight based on the total weight of the first exfoliated graphite composite sheet. Preferably, the first exfoliated graphite composite sheet further comprises particles of non-expandable graphite or carbon in the amount of between 3% and 60% by weight based on the total weight of the non-expandable particles and the expanded graphite. Further preferably, the laminate comprises a second exfoliated graphite composite sheet bonded to the second surface of the metal sheet to form a three-layer laminate. Surface flow channels and other desired geometric features can be built onto the exterior surfaces of the laminate to form a flow field plate or bipolar plate. The resulting laminate has an exceptionally high thickness-direction conductivity and excellent resistance to gas permeation.
Boosman, R; Németh, F; Gruys, E
1991-07-01
This review deals with the features of clinical and subclinical laminitis in cattle. Prominent clinical signs of acute laminitis are a tender gait and arched back. The sole horn reveals red and yellowish discolourations within five days. In subacute and chronic cases clinical signs are less severe. In chronic laminitis the shape of the claws is altered. Laminitis is frequently followed by sole ulceration and white zone lesions. Blood tests showed no significant changes for laminitic animals. Arteriographic studies of claws affected by laminitis indicated that blood vessels had narrowed lumens. Gross pathology revealed congestion of the corium and rotation of the distal phalanx. Histopathologic studies indicate that laminitis is associated with changes of the vasculature. Peripartum management and nutrition are important factors in its aetiology. It is hypothesised that laminitis is evoked by disturbed digital circulation. In the pathogenesis of acute laminitis three factors are considered important: the occurrence of thrombosis, haemodynamic aspects of the corium, and endotoxins which trigger these pathologic events.
Effect of laminate edge conditions on the formation of microvoids in composite laminates
Anderson, J. P.; Altan, M. C.
2015-05-01
Manufacturing defects such as microvoids are common in thermoset composite components and are known to negatively affect their strength. The resin pressure developed in and the resin flow out from the laminates during cure have been reported to be the primary factors influencing the final void content of a composite component. In this work, the effect of laminate edge conditions during the cure process on the formation of microvoids was experimentally investigated. This was achieved by fabricating eight-ply laminates from TenCate® BT250/7781 prepreg in a hot-press at a constant cure pressure of 170 kPa while limiting the laminate perimeter available for resin flow by 0%, 25%, 50%, 75%, and 100%. The individual plies of these five laminates were conditioned at 99% relative humidity before curing to maximize the moisture present in the lay-up before fabrication. The presence of moisture in the lay-ups was expected to promote void formation and allow the effect of restricting flow at the edges of a laminate to be better identified. The restriction of resin outflow was found to cause the average characteristic void diameter to decrease by 17% and void content to rise by 33%. This phenomenon was identified to be a result of the outflow restriction increasing the number of voids trapped within the laminate and indicates that for laminates cured at low pressures resin outflow is the dominant mechanism for void reduction.
Structural properties of laminated Douglas fir/epoxy composite material
Spera, D.A. (National Aeronautics and Space Administration, Cleveland, OH (USA). Lewis Research Center); Esgar, J.B. (Sverdrup Technology, Inc., Cleveland, OH (USA)); Gougeon, M.; Zuteck, M.D. (Gougeon Bros., Bay City, MI (USA))
1990-05-01
This publication contains a compilation of static and fatigue and strength data for laminated-wood material made from Douglas fir and epoxy. Results of tests conducted by several organizations are correlated to provide insight into the effects of variables such as moisture, size, lamina-to-lamina joint design, wood veneer grade, and the ratio of cyclic stress to steady stress during fatigue testing. These test data were originally obtained during development of wood rotor blades for large-scale wind turbines of the horizontal-axis (propeller) configuration. Most of the strength property data in this compilation are not found in the published literature. Test sections ranged from round cylinders 2.25 in. in diameter to rectangular slabs 6 in. by 24 in. in cross section and approximately 30 ft long. All specimens were made from Douglas fir veneers 0.10 in. thick, bonded together with the WEST epoxy system developed for fabrication and repair of wood boats. Loading was usually parallel to the grain. Size effects (reduction in strength with increase in test volume) are observed in some of the test data, and a simple mathematical model is presented that includes the probability of failure. General characteristics of the wood/epoxy laminate are discussed, including features that make it useful for a wide variety of applications. 9 refs.
The electrostatic cylindrical sheath in a plasma
Wang Chunhua; Sun Xiaoxia; Bai Dongxue
2004-01-01
The electrostatic sheath with a cylindrical geometry in an ion-electron plasma is investigated. Assuming a Boltzmann response to electrons and cold ions with bulk flow, it is shown that the radius of the cylindrical geometry do not affect the sheath potential significantly. The authors also found that the sheath potential profile is steeper in the cylindrical sheath compared to the slab sheath. The distinct feature of the cylindrical sheath is that the ion density distribution is not monotonous. The sheath region can be divided into three regions, two ascendant regions and one descendant region. (author)
The influence of lay-up and thickness on composite impact damage and compression strength
Guynn, E. G.; Obrien, T. K.
1985-01-01
The effects of composite stacking sequence, thickness, and percentage of zero-degree plies on the size, shape, and distribution of delamination through the laminate thickness and on residual compression strength following impact were studied. Graphite/epoxy laminates were impacted with an 0.5 inch diameter aluminum sphere at a specific low or high velocity. Impact damage was measured nondestructively by ultrasonic C-scans and X-radiography and destructively by the deply technique, and compression strength tests were performed. It was found that differences in compression failure strain due to stacking sequence were small, while laminates with very low percentages of zero-degree plies had similar failure loads but higher failure strains than laminates with higher percentages of zero-degree plies. Failure strain did not correlate with planar impact damage area, and delaminations in impact regions were associated with matrix cracking.
Xiping Wang; Robert J. Ross; Brian K. Brashaw; Steven A. Verhey; John W. Forsman; John R. Erickson
2003-01-01
The study described in this report was conducted to examine the flexural properties of laminated veneer lumber (LVL) manufactured from red maple veneer. Ultrasonically rated veneer, which was peeled from low value red maple saw-logs, was fabricated into 1/2-in.-(1.3-cm-) and 2-in.-(5-cm-) thick LVL billets. The flexural properties of the billets and of corresponding...
Study on mechanical properties of laminated rubber bearing with small shape factor
Mazda, T.; Ootori, Y.; Yabana, S.; Hirata, K.; Ishida, K.
1995-01-01
Laminated rubber bearings with a small shape factor are regarded as one of the most promising isolation devices to reduce the vertical seismic load of a nuclear power plant. In this study, three types of natural rubber bearings with different aspect ratios (diameter/total thickness of rubber) and one high-damping rubber bearing are tested under varied loading conditions. Basic characteristics and ultimate characteristics of the bearings are made clear, and applicability of estimation formula and analysis method are verified
Microcracking in composite laminates under thermal and mechanical loading. Thesis
Maddocks, Jason R.
1995-01-01
Composites used in space structures are exposed to both extremes in temperature and applied mechanical loads. Cracks in the matrix form, changing the laminate thermoelastic properties. The goal of the present investigation is to develop a predictive methodology to quantify microcracking in general composite laminates under both thermal and mechanical loading. This objective is successfully met through a combination of analytical modeling and experimental investigation. In the analysis, the stress and displacement distributions in the vicinity of a crack are determined using a shear lag model. These are incorporated into an energy based cracking criterion to determine the favorability of crack formation. A progressive damage algorithm allows the inclusion of material softening effects and temperature-dependent material properties. The analysis is implemented by a computer code which gives predicted crack density and degraded laminate properties as functions of any thermomechanical load history. Extensive experimentation provides verification of the analysis. AS4/3501-6 graphite/epoxy laminates are manufactured with three different layups to investigate ply thickness and orientation effects. Thermal specimens are cooled to progressively lower temperatures down to -184 C. After conditioning the specimens to each temperature, cracks are counted on their edges using optical microscopy and in their interiors by sanding to incremental depths. Tensile coupons are loaded monotonically to progressively higher loads until failure. Cracks are counted on the coupon edges after each loading. A data fit to all available results provides input parameters for the analysis and shows them to be material properties, independent of geometry and loading. Correlation between experiment and analysis is generally very good under both thermal and mechanical loading, showing the methodology to be a powerful, unified tool. Delayed crack initiation observed in a few cases is attributed to a
Intelligent processing for thick composites
Shin, Daniel Dong-Ok
2000-10-01
Manufacturing thick composite parts are associated with adverse curing conditions such as large in-plane temperature gradient and exotherms. The condition is further aggravated because the manufacturer's cycle and the existing cure control systems do not adequately counter such affects. In response, the forecast-based thermal control system is developed to have better cure control for thick composites. Accurate cure kinetic model is crucial for correctly identifying the amount of heat generated for composite process simulation. A new technique for identifying cure parameters for Hercules AS4/3502 prepreg is presented by normalizing the DSC data. The cure kinetics is based on an autocatalytic model for the proposed method, which uses dynamic and isothermal DSC data to determine its parameters. Existing models are also used to determine kinetic parameters but rendered inadequate because of the material's temperature dependent final degree of cure. The model predictions determined from the new technique showed good agreement to both isothermal and dynamic DSC data. The final degree of cure was also in good agreement with experimental data. A realistic cure simulation model including bleeder ply analysis and compaction is validated with Hercules AS4/3501-6 based laminates. The nonsymmetrical temperature distribution resulting from the presence of bleeder plies agreed well to the model prediction. Some of the discrepancies in the predicted compaction behavior were attributed to inaccurate viscosity and permeability models. The temperature prediction was quite good for the 3cm laminate. The validated process simulation model along with cure kinetics model for AS4/3502 prepreg were integrated into the thermal control system. The 3cm Hercules AS4/3501-6 and AS4/3502 laminate were fabricated. The resulting cure cycles satisfied all imposed requirements by minimizing exotherms and temperature gradient. Although the duration of the cure cycles increased, such phenomena was
2011-03-01
Full Text Available In consequence of an increased interest in using endless carbon fibre reinforced thermoplastic composites (TPC, automated and highly productive processing technologies for cutting and trimming steps of consolidated materials are sought. In this paper, the influence on the thermal effect caused by laser cutting with respect to static strength properties of TPC based on a polyphenylene sulfide (PPS matrix is studied. For the cutting experiments, consolidated TPC laminates at varying thicknesses up to s = 3.1 mm and a disc laser emitting at a wavelength of λ = 1030 nm at a maximum output power of PL = 2 kW are used. For the first time, the resulting magnitude of the heat affected zone (HAZ at the cutting edge of the composite material is correlated with interlaminar shear strength tests. The results are compared to specimens prepared by milling and abrasive water jet cutting. Depending on the laminate thickness, the laser treated TPC samples show comparable properties to those of conventionally processed specimens. A reduced load bearing area, as a consequence of damaged fibre-matrix-adhesion due to laser impact, is identified as main factor for the reduction of interlaminar shear strengths for higher laminate thicknesses.
Diffusion from cylindrical waste forms
Thomas, G.F.
1985-05-01
The diffusion of a single component material from a finite cylindrical waste form, initially containing a uniform concentration of the material, is investigated. Under the condition that the cylinder is maintained in a well-stirred bath, expressions for the fractional inventory leached and the leach rate are derived with allowance for the possible permanent immobilization of the diffusant through its decay to a stable product and/or its irreversible reaction with the waste form matrix. The usefulness of the reported results in nuclear waste disposal applications is emphasized. The results reported herein are related to those previously derived at Oak Ridge National Laboratory by Bell and Nestor. A numerical scheme involving the partial decoupling of nested infinite summations and the use of rapidly converging rational approximants is recommended for the efficient implementation of the expressions derived to obtain reliable estimates of the bulk diffusion constant and the rate constant describing the diffusant-waste form interaction from laboratory data
Calculation of neutron albedo from laminated semiinfinite media
Dobrynin, Yu.L.; Mikaehlyan, L.A.; Skorokhvatov, M.D.
1978-01-01
A version of a laminated neutron detector with increased efficiency for recording external neutron fluxes by gamma-quanta from neutron capture is considered. The detector comprises two zones. The first zone constitutes an absorbent layer (europium oxide) 0.5 cm thick, and the second one is a moderator (water with gadolinium salt at the concentration of 0.8 g/l). Mono-energetic neutrons fall normally onto the detector surface. Neutron energy varied from 0.1 eV to MeV. The results of calculations of the integral numerical current albedo (INCA) of neutrons by the Monte Carlo method are presented. The INCA dependences on neutron energy are obtained for one moderator with different gadolinium contents; for the absorbent with the moderator containing and lacking the gadolinium. The resultant dependences are indicative of preferential capture of neutrons by the gadolinium in the moderator, this being more desirable for recording neutrons in the (n, γ) reaction
Compression of laminated composite beams with initial damage
Breivik, Nicole L.; Gurdal, Zafer; Griffin, O. H., Jr.
1993-01-01
The effect of isolated damage modes on the compressive strength and failure characteristics of laminated composite test specimens were evaluated experimentally and numerically. In addition to specimens without initial damage, specimens with three types of initial damage were considered: (1) specimens with short delaminations distributed evenly through the specimen thickness, (2) specimens with few long delaminations, and (3) specimens with local fiber damage in the surface plies under the three-point bend contact point. It was found that specimens with short multiple delamination experienced the greatest reduction in compression strength compared to the undamaged specimens. Single delaminations far from the specimen surface had little effect on the final compression strength, and moderate strength reduction was observed for specimens with localized surface ply damage.
Processing and impact properties of steel based laminated composites
Carreno, F.; Pozuelo, M.; Chao, J.; Ruano, O. A.
2001-01-01
A seven layers steel based laminated composite (four ultra-high carbon steel, UHCS, layers and three mild steel, MS layers) has been processed by rolling bonding and its microstructure and impact properties have been studied. Suitable parameters of temperature and thickness reduction were selected to obtain a finer microstructure relative to the original materials components. This finer microstructure induces improved mechanical properties. Charpy impact tests values in both crack arrester and crack divider orientations improve the values of the UHCS constituent materials. Furthermore, the crack arrester orientation value exceed that of the MS material. The delamination, which is controlled by interface bonding, plays a key role defecting the crack, absorbing energy and imposing the nucleation of new cracks in the next materials layers. (Author) 10 refs
Evaluation of Behaviours of Laminated Glass
Sable, L.; Japins, G.; Kalnins, K.
2015-11-01
Visual appearance of building facades and other load bearing structures, which now are part of modern architecture, is the reason why it is important to investigate in more detail the reliability of laminated glass for civil structures. Laminated glass in particular has become one of the trendy materials, for example Apple© stores have both load carrying capacity and transparent appearance. Glass has high mechanical strength and relatively medium density, however, the risk of sudden brittle failure like concrete or other ceramics determine relatively high conservatism in design practice of glass structures. This should be changed as consumer requirements evolve calling for a safe and reliable design methodology and corresponding building standards. A design methodology for glass and glass laminates should be urgently developed and included as a chapter in Eurocode. This paper presents initial experimental investigation of behaviour of simple glass sheets and laminated glass samples in 4-point bending test. The aim of the current research is to investigate laminated glass characteristic values and to verify the obtained experimental results with finite element method for glass and EVA material in line with future European Structural Design of Glass Components code.
Spiral modes in cold cylindrical systems
Robe, H.
1975-01-01
The linearized hydrodynamical equations governing the non-axisymmetric free modes of oscillation of cold cylindrical stellar systems are separated in cylindrical coordinates and solved numerically for two models. Short-wavelength unstable modes corresponding to tight spirals do not exist; but there exists an unstable growing mode which has the form of trailing spirals which are quite open. (orig.) [de
Hybrid Laminates for Application in North Conditions
Antipov, V. V.; Oreshko, E. I.; Erasov, V. S.; Serebrennikova, N. Yu.
2016-11-01
A hybrid aluminum-lithium alloy/SIAL laminate as a possible material for application in structures operated in North conditions is considered. The finite-element method is used for a buckling stability analysis of hybrid panels, bars, and plates. A technique allowing one to compare the buckling stability of multilayered hybrid plates is offered. Compression tests were run on a hybrid laminate wing panel as a prototype of the top panel of TU-204SM airplane made from a high-strength B95T2 aluminum alloy. It turned out that the lighter composite panel had a higher load-carrying capacity than the aluminum one. Results of investigation into the properties the hybrid aluminum-lithium alloy/SIAL laminate and an analysis of scientific-technical data on this subject showed that this composite material could be used in the elements of airframes, including those operated in north conditions.
Plated lamination structures for integrated magnetic devices
Webb, Bucknell C.
2014-06-17
Semiconductor integrated magnetic devices such as inductors, transformers, etc., having laminated magnetic-insulator stack structures are provided, wherein the laminated magnetic-insulator stack structures are formed using electroplating techniques. For example, an integrated laminated magnetic device includes a multilayer stack structure having alternating magnetic and insulating layers formed on a substrate, wherein each magnetic layer in the multilayer stack structure is separated from another magnetic layer in the multilayer stack structure by an insulating layer, and a local shorting structure to electrically connect each magnetic layer in the multilayer stack structure to an underlying magnetic layer in the multilayer stack structure to facilitate electroplating of the magnetic layers using an underlying conductive layer (magnetic or seed layer) in the stack as an electrical cathode/anode for each electroplated magnetic layer in the stack structure.
Optimal Design of Laminated Composite Beams
Blasques, José Pedro Albergaria Amaral
model for the analysis of laminated composite beams is proposed. The structural analysis is performed in a beam finite element context. The development of a finite element based tool for the analysis of the cross section stiffness properties is described. The resulting beam finite element formulation...... is able to account for the effects of material anisotropy and inhomogeneity in the global response of the beam. Beam finite element models allow for a significant reduction in problem size and are therefore an efficient alternative in computationally intensive applications like optimization frameworks...... design of laminated composite beams. The devised framework is applied in the optimal design of laminated composite beams with different cross section geometries and subjected to different load cases. Design criteria such as beam stiffness, weight, magnitude of the natural frequencies of vibration...
On Subsurface Crack Growth in Fibre Metal Laminate Materials
Randall, Christian
2003-01-01
Fatigue crack growth in fibre metal laminates (FMLs) is significantly more complex than in monolithic materials due to the interaction of various physical mechanisms that govern the growth of cracks in laminates...
Fields, T.; Guarino, V.; Petereit, E.; Schoessow, P.; Thompson, K.
1996-01-01
This proposal describes an alternative to the reference design for the construction of the toroidal magnet for the detector for the MINOS experiment. This design proposes to construct the steel planes from several steel sheets and laminate them into the required thickness of four centimeters. The 8 meter planes are constructed by cutting all of the steel plates to the same size, which is pie a pie shaped segment of either 30 or 22.5 degrees each. All of the plates in the construction are identical, which is conducive to rapid production and lower cost. The advantages of the proposed laminated construction over the reference design are listed in this paper
Chee Zhou Kam
2013-01-01
Full Text Available A laminated composite plate element with an interface description is developed using the finite element approach to investigate the bending performance of two-layer cross-ply laminated composite plates in presence of a diagonally perturbed localized interfacial degeneration between laminae. The stiffness of the laminate is expressed through the assembly of the stiffnesses of lamina sub-elements and interface element, the latter of which is formulated adopting the well-defined virtually zero-thickness concept. To account for the extent of both shear and axial weak bonding, a degeneration ratio is introduced in the interface formulation. The model has the advantage of simulating a localized weak bonding at arbitrary locations, with various degeneration areas and intensities, under the influence of numerous boundary conditions since the interfacial description is expressed discretely. Numerical results show that the bending behavior of laminate is significantly affected by the aforementioned parameters, the greatest effect of which is experienced by those with a localized total interface degeneration, representing the case of local delamination.
Davood Askari and Mehrdad N Ghasemi-Nejhad
2012-01-01
Full Text Available The main objective is to improve the most commonly addressed weakness of the laminated composites (i.e. delamination due to poor interlaminar strength using carbon nanotubes (CNTs as reinforcement between the laminae and in the transverse direction. In this work, a chemical vapor deposition technique has been used to grow dense vertically aligned arrays of CNTs over the surface of chemically treated two-dimensionally woven cloth and fiber tows. The nanoforest-like fabrics can be used to fabricate three-dimensionally reinforced laminated nanocomposites. The presence of CNTs aligned normal to the layers and in-between the layers of laminated composites is expected to considerably enhance the properties of the laminates. To demonstrate the effectiveness of our approach, composite single lap-joint specimens were fabricated for interlaminar shear strength testing. It was observed that the single lap-joints with through-the-thickness CNT reinforcement can carry considerably higher shear stresses and strains. Close examination of the test specimens showed that the failure of samples with CNT nanoforests was completely cohesive, while the samples without CNT reinforcement failed adhesively. This concludes that the adhesion of adjacent carbon fabric layers can be considerably improved owing to the presence of vertically aligned arrays of CNT nanoforests.
Askari, Davood; Ghasemi-Nejhad, Mehrdad N
2012-08-01
The main objective is to improve the most commonly addressed weakness of the laminated composites (i.e. delamination due to poor interlaminar strength) using carbon nanotubes (CNTs) as reinforcement between the laminae and in the transverse direction. In this work, a chemical vapor deposition technique has been used to grow dense vertically aligned arrays of CNTs over the surface of chemically treated two-dimensionally woven cloth and fiber tows. The nanoforest-like fabrics can be used to fabricate three-dimensionally reinforced laminated nanocomposites. The presence of CNTs aligned normal to the layers and in-between the layers of laminated composites is expected to considerably enhance the properties of the laminates. To demonstrate the effectiveness of our approach, composite single lap-joint specimens were fabricated for interlaminar shear strength testing. It was observed that the single lap-joints with through-the-thickness CNT reinforcement can carry considerably higher shear stresses and strains. Close examination of the test specimens showed that the failure of samples with CNT nanoforests was completely cohesive, while the samples without CNT reinforcement failed adhesively. This concludes that the adhesion of adjacent carbon fabric layers can be considerably improved owing to the presence of vertically aligned arrays of CNT nanoforests.
Minimization of complementary energy to predict shear modulus of laminates with intralaminar cracks
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.
Modeling Bistable Composite Laminates for Piezoelectric Morphing Structures
Darryl V. Murray; Oliver J. Myers
2013-01-01
A sequential modeling effort for bistable composite laminates for piezoelectric morphing structures is presented. Thin unsymmetric carbon fiber composite laminates are examined for use of morphing structures using piezoelectric actuation. When cooling from the elevated cure temperature to room temperature, these unsymmetric composite laminates will deform. These postcure room temperature deformation shapes can be used as morphing structures. Applying a force to these deformed laminates will c...
Investigation into the Quality of Thermally Treated Package Lamination
Darius Kazlauskas
2011-02-01
Full Text Available The article deals with the problem of delaminating the package after pasteurization at relatively high temperatures. The main parameters of the lamination process influencing lamination strength were determined. The role of the amount of lamination glue and tension in the rewinder for two glue types were experimentally examined defining lamination regimes at which the process of delamination is excluded.Article in Lithuanian
Properties of Chitosan-Laminated Collagen Film
Vera Lazić
2012-01-01
Full Text Available The objective of this study is to determine physical, mechanical and barrier properties of chitosan-laminated collagen film. Commercial collagen film, which is used for making collagen casings for dry fermented sausage production, was laminated with chitosan film layer in order to improve the collagen film barrier properties. Different volumes of oregano essential oil per 100 mL of filmogenic solution were added to chitosan film layer: 0, 0.2, 0.4, 0.6 and 0.8 mL to optimize water vapour barrier properties. Chitosan layer with 0.6 or 0.8 % of oregano essential oil lowered the water vapour transmission rate to (1.85±0.10·10–6 and (1.78±0.03·10–6 g/(m2·s·Pa respectively, compared to collagen film ((2.51±0.05·10–6 g/(m2·s·Pa. However, chitosan-laminated collagen film did not show improved mechanical properties compared to the collagen one. Tensile strength decreased from (54.0±3.8 MPa of the uncoated collagen film to (36.3±4.0 MPa when the film was laminated with 0.8 % oregano essential oil chitosan layer. Elongation at break values of laminated films did not differ from those of collagen film ((18.4±2.7 %. Oxygen barrier properties were considerably improved by lamination. Oxygen permeability of collagen film was (1806.8±628.0·10–14 cm3/(m·s·Pa and values of laminated films were below 35·10–14 cm3/(m·s·Pa. Regarding film appearance and colour, lamination with chitosan reduced lightness (L and yellowness (+b of collagen film, while film redness (+a increased. These changes were not visible to the naked eye.
Lu Junqing; Yang Lin; Yoon, Jae Hong; Cho, Tong Yul; Tao Guoqing
2008-01-01
Severe asymmetry of the metal deposits on the trench sidewalls occurs near the wafer edge during low pressure ionized metal physical vapor deposition of Cu seed layer for microprocessor interconnects. To investigate this process and mitigate the asymmetry, an analytical view factor model based on the analogy between metal sputtering and diffuse thermal radiation was constructed to investigate deposition uniformity and symmetry for cylindrical target sputtering in low pressure (below 0.1 Pa) ionized Cu physical vapor deposition. The model predictions indicate that as the distance from the cylindrical target to wafer increases, the metal film thickness becomes more uniform across the wafer and the asymmetry of the metal deposits at the wafer edge increases significantly. These trends are similar to those for planar targets. To minimize the asymmetry, the height of the cylindrical target should be kept at a minimum. For cylindrical targets, the outward-facing sidewall of the trench could receive more direct Cu fluxes than the inward-facing one when the target to wafer distance is short. The predictions also indicate that increasing the diameter of the cylindrical target could significantly reduce the asymmetry in metal deposits at the wafer edge and make the film thickness more uniform across the wafer
Intrinsic cylindrical and spherical waves
Ludlow, I K
2008-01-01
Intrinsic waveforms associated with cylindrical and spherical Bessel functions are obtained by eliminating the factors responsible for the inverse radius and inverse square radius laws of wave power per unit area of wavefront. The resulting expressions are Riccati-Bessel functions for both cases and these can be written in terms of amplitude and phase functions of order v and wave variable z. When z is real, it is shown that a spatial phase angle of the intrinsic wave can be defined and this, together with its amplitude function, is systematically investigated for a range of fixed orders and varying z. The derivatives of Riccati-Bessel functions are also examined. All the component functions exhibit different behaviour in the near field depending on the order being less than, equal to or greater than 1/2. Plots of the phase angle can be used to display the locations of the zeros of the general Riccati-Bessel functions and lead to new relations concerning the ordering of the real zeros of Bessel functions and the occurrence of multiple zeros when the argument of the Bessel function is fixed
Diffusion in a cylindrical plasma
Reid, J.
1977-04-01
Modern plasma containment devices, such as the Tokamak, employ magnetic fields which are toroidal in shape. They are able to contain a plasma for times approaching a second. Magnetohydrodynamics (M.H.D.) is one of the most attractive theoretical methods for understanding their behaviour, but the equations involved are complex non-linear partial differential equations, and analytic methods are not available for their solution. Numerical methods must be used. A model system of equations representing a cylindrical plasma with no axial variation is considered. It is convenient to introduce a flux function psi for the component of the magnetic field directed around the axis of the cylinder, called the poloidal field, and the M.H.D. equations are rewritten in terms of psi. This produces a set of highly coupled equations describing the evolution of the flux function, the axial field and the plasma pressure. Various steps are taken to gain a better understanding of the properties of these equations. (author)
YagnaSri, P.; Siddiqui, Maimuna; Vijaya Nirmala, M.
2018-03-01
The objective of the work is to develop the higher order theory for piezoelectric composite laminated plates with zigzag function and to determine the thermal characteristics of piezoelectric laminated plate with zig zag function for different aspect ratios (a/h), thickness ratios (z/h) and voltage and also to evaluate electric potential function by solving second order differential equation satisfying electric boundary conditions along the thickness direction of piezoelectric layer. The related functions and derivations for equation of motion are obtained using the dynamic version of the principle of virtual work or Hamilton’s principle. The solutions are obtained by using Navier’s stokes method for anti-symmetric angle-ply with specific type of simply supported boundary conditions. Computer programs have been developed for realistic prediction of stresses and deflections for various sides to thickness ratios (a/h) and voltages.
Jeevan Kumar, N.; Ramesh Babu, P.
2018-04-01
This paper presents the numerical study of the mode I and mode II interlaminar crack growth arrest in hybrid laminated curved composite stiffened joint with Z-fibre reinforcement. A FE model of hybrid laminated skin-stiffener joint reinforced with Z-pins is developed to investigate the effect of Z- fibre pins on mode I and mode II crack growth where the delamination is embedded inbetween the skin and stiffener interface. A finite element model was developed using S4R element of a 4-node doubly curved thick shell elements to model the composite laminates and non linear interface elements to simulate the reinforcements. The numerical analyses revealed that Z-fibre pinning were effective in suppressing the delamination growth when propagated due to applied loads. Therefore, the Z-fibre technique effectively improves the crack growth resistance and hence arrests or delays crack growth extension.
Numerical Simulation of the Layer-Bylayer Destruction of Cylindrical Shells Under Explosive Loading
Abrosimov, N. A.; Novoseltseva, N. A.
2015-09-01
A technique of numerical analysis of the influence of reinforcement structure on the nature of the dynamic response and the process of layer-by-layer destruction of layered fiberglass cylindrical shells under an axisymmetric internal explosive loading is elaborated. The kinematic model of deformation of the laminate package is based on a nonclassical theory of shells. The geometric dependences are based on simple quadratic relations of the nonlinear theory of elasticity. The relationship between the stress and strain tensors are established by using Hooke's law for orthotropic bodies with account of degradation of stiffness characteristics of the multilayer composite due to the local destruction of some its elementary layers. An energetically consistent system of dynamic equations for composite cylindrical shells is obtained by minimizing the functional of total energy of the shell as a three-dimensional body. The numerical method for solving the formulated initial boundary-value problem is based on an explicit variational-difference scheme. Results confirming the reliability of the method used to analyze the influence of reinforcement structure on the character of destruction and the bearing capacity of pulse-loaded cylindrical shells are presented.
Lamination sheet of AA BST magnet
CERN PhotoLab
1979-01-01
The AA had 2 types of bending magnets: BLG (window-frame, long and narrow)and BST (H-type, short and wide). The BST had a very wide aperture, 0.564 m of "good field". To demonstrate the size, the petite AA secretary, Val Mansfield, poses with a lamination sheet. See also 7811105, 7906163, 8006050.
Laminated Root Rot of Western Conifers
E.E. Nelson; N.E. Martin; R.E. Williams
1981-01-01
Laminated root rot is caused by the native fungus Phellinus weirii (Murr.) Gilb. It occurs throughout the Northwestern United States and in southern British Columbia, Canada. The disease has also been reported in Japan and Manchuria. In the United States, the pathogen is most destructive in pure Douglas-fir stands west of the crest of the Cascade Range in Washington...
[Laminitis in cattle: a literature review].
Lischer, C; Ossent, P
1994-10-01
Worldwide afflictions of the claws belong to the economically important diseases in dairy cattle. The significance of laminitis has gained importance in the last years since the condition is regarded as the most important predisposing factor for the development of lesions such as sole ulcer, white line disease and heel horn erosion. Apart from the clinical stages (acute, subacute, chronic, chronic-recurrent) there is also a subclinical form of laminitis which does not cause lameness. It is characterized by soft yellowish sole and heel horn with haemorrhages in the sole and along the white line. Laminitis is a multifactorial event in which nutrition, genetic disposition and the perinatal period, combined with the associated diseases of high-yielding cows, have a particular significance. Currently, two principally different hypotheses on the pathogenesis are discussed. The generally accepted theory bases on a disturbance in the microcirculation of the corium. According to the other theory the circulatory disturbances are secondary to changes which occur in the horn producing cells of the stratum basale of the epidermis. The predisposing factors and the pathogenesis of laminitis are discussed in the light of possible therapeutic and prophylactic measures.
Nuclear Structures Surrounding Internal Lamin Invaginations
Legartová, Soňa; Stixová, Lenka; Laur, O.; Kozubek, Stanislav; Sehnalová, Petra; Bártová, Eva
2014-01-01
Roč. 115, č. 3 (2014), s. 476-487 ISSN 0730-2312 R&D Projects: GA MŠk(CZ) LD11020 Institutional support: RVO:68081707 Keywords : LAMINS * NUCLEAR PORES * CHROMATIN Subject RIV: BO - Biophysics Impact factor: 3.263, year: 2014
Doped LZO buffer layers for laminated conductors
Paranthaman, Mariappan Parans [Knoxville, TN; Schoop, Urs [Westborough, MA; Goyal, Amit [Knoxville, TN; Thieme, Cornelis Leo Hans [Westborough, MA; Verebelyi, Darren T [Oxford, MA; Rupich, Martin W [Framingham, MA
2010-03-23
A laminated conductor includes a metallic substrate having a surface, a biaxially textured buffer layer supported by the surface of the substrate, the biaxially textured buffer layer comprising LZO and a dopant for mitigating metal diffusion through the LZO, and a biaxially textured conductor layer supported by the biaxially textured buffer layer.
Tropicalized Lambda Lengths, Measured Laminations and Convexity
C. Penner, R.
This work uncovers the tropical analogue for measured laminations of the convex hull construction of decorated Teichmueller theory, namely, it is a study in coordinates of geometric degeneration to a point of Thurston's boundary for Teichmueller space. This may offer a paradigm for the extension ...
Progressive delamination in polymer matrix composite laminates: A new approach
Chamis, C. C.; Murthy, P. L. N.; Minnetyan, L.
1992-01-01
A new approach independent of stress intensity factors and fracture toughness parameters has been developed and is described for the computational simulation of progressive delamination in polymer matrix composite laminates. The damage stages are quantified based on physics via composite mechanics while the degradation of the laminate behavior is quantified via the finite element method. The approach accounts for all types of composite behavior, laminate configuration, load conditions, and delamination processes starting from damage initiation, to unstable propagation, and to laminate fracture. Results of laminate fracture in composite beams, panels, plates, and shells are presented to demonstrate the effectiveness and versatility of this new approach.
Simulating squeeze flows in multiaxial laminates using an improved TIF model
Ibañez, R.; Abisset-Chavanne, Emmanuelle; Chinesta, Francisco
2017-10-01
Thermoplastic composites are widely considered in structural parts. In this paper attention is paid to squeeze flow of continuous fiber laminates. In the case of unidirectional prepregs, the ply constitutive equation is modeled as a transversally isotropic fluid, that must satisfy both the fiber inextensibility as well as the fluid incompressibility. When laminate is squeezed the flow kinematics exhibits a complex dependency along the laminate thickness requiring a detailed velocity description through the thickness. In a former work the solution making use of an in-plane-out-of-plane separated representation within the PGD - Poper Generalized Decomposition - framework was successfully accomplished when both kinematic constraints (inextensibility and in-compressibility) were introduced using a penalty formulation for circumventing the LBB constraints. However, such a formulation makes difficult the calculation on fiber tractions and compression forces, the last required in rheological characterizations. In this paper the former penalty formulation is substituted by a mixed formulation that makes use of two Lagrange multipliers, while addressing the LBB stability conditions within the separated representation framework, questions never until now addressed.
Mercan, Kadir; Demir, Çiǧdem; Civalek, Ömer
2016-01-01
In the present manuscript, free vibration response of circular cylindrical shells with functionally graded material (FGM) is investigated. The method of discrete singular convolution (DSC) is used for numerical solution of the related governing equation of motion of FGM cylindrical shell. The constitutive relations are based on the Love's first approximation shell theory. The material properties are graded in the thickness direction according to a volume fraction power law indexes. Frequency values are calculated for different types of boundary conditions, material and geometric parameters. In general, close agreement between the obtained results and those of other researchers has been found.
Goyal, T. [Indian Institute of Technology Kanpur. Dept. of Aerospace Engineering, UP (India); Gupta, R. [Infotech Enterprises Ltd., Hyderabad (India)
2012-07-01
In this work, minimum weight-cost design for laminated composites is presented. A genetic algorithm has been developed for the optimization process. Maximum-Stress, Tsai-Wu and Tsai-Hill failure criteria have been used along with buckling analysis parameter for the margin of safety calculations. The design variables include three materials; namely Carbon-Epoxy, Glass-Epoxy, Kevlar-Epoxy; number of plies; ply orientation angles, varying from -75 deg. to 90 deg. in the intervals of 15 deg. and ply thicknesses which depend on the material in use. The total cost is a sum of material cost and layup cost. Layup cost is a function of the ply angle. Validation studies for solution convergence and weight-cost inverse proportionality are carried out. One set of results for shear loading are also validated from literature for a particular case. A Pareto-Optimal solution set is demonstrated for biaxial loading conditions. It is then extended to applied moments. It is found that global optimum for a given loading condition is a function of the failure criteria for shear loading, with Maximum Stress criteria giving the lightest-cheapest and Tsai-Wu criteria giving the heaviest-costliest optimized laminates. Optimized weight results are plotted from the three criteria to do a comparative study. This work gives a global optimized laminated composite and also a set of other local optimum laminates for a given set of loading conditions. The current algorithm also provides with adequate data to supplement the use of different failure criteria for varying loadings. This work can find use in the industry and/or academia considering the increased use of laminated composites in modern wind blades. (Author)
Modeling the kinematics of multi-axial composite laminates as a stacking of 2D TIF plies
Ibañez, Ruben; Abisset-Chavanne, Emmanuelle; Chinesta, Francisco; Huerta, Antonio
2016-10-01
Thermoplastic composites are widely considered in structural parts. In this paper attention is paid to sheet forming of continuous fiber laminates. In the case of unidirectional prepregs, the ply constitutive equation is modeled as a transversally isotropic fluid, that must satisfy both the fiber inextensibility as well as the fluid incompressibility. When the stacking sequence involves plies with different orientations the kinematics of each ply during the laminate deformation varies significantly through the composite thickness. In our former works we considered two different approaches when simulating the squeeze flow induced by the laminate compression, the first based on a penalty formulation and the second one based on the use of Lagrange multipliers. In the present work we propose an alternative approach that consists in modeling each ply involved in the laminate as a transversally isotropic fluid - TIF - that becomes 2D as soon as incompressibility constraint and plane stress assumption are taken into account. Thus, composites laminates can be analyzed as a stacking of 2D TIF models that could eventually interact by using adequate friction laws at the inter-ply interfaces.
Effects of Constituents and Lay-up Configuration on Drop-Weight Tests of Fiber-Metal Laminates
Liu, Yanxiong; Liaw, Benjamin
2010-02-01
Impact responses and damage of various fiber-metal laminates were studied using a drop-weight instrument with the post-impact damage characteristics being evaluated through ultrasonic and mechanical sectioning techniques. The first severe failure induced by the low-velocity drop-weight impact occurred as delamination between the aluminum and fiber-epoxy layers at the non-impact side. It was followed by a visible shear crack in the outer aluminum layer on the non-impact face. Through-thickness shear cracks in the aluminum sheets and severe damage in the fiber laminated layers (including delamination between adjacent fiber-epoxy laminae with different fiber orientations) developed under higher energy impacts. The impact properties of fiber-metal laminates varied with different constituent materials and fiber orientations. Since it was punched through easily, the aramid-fiber reinforced fiber-metal laminates (ARALL) offered poorer impact resistance than the glass-fiber reinforced fiber-metal laminates (GLARE). Tougher and more ductile aluminum alloys improved the impact resistance. GLARE made of cross-ply prepregs provided better impact resistance than GLARE with unidirectional plies.
Cylindrical fabric-confined soil structures
Harrison, Richard A.
A cylindrical fabric-soil structural concept for implementation on the moon and Mars which provides many advantages is proposed. The most efficient use of fabric is to fashion it into cylindrical tubes, creating cylindrical fabric-confined soil structures. The length, diameter, and curvature of the tubes will depend on the intended application. The cylindrical hoop forces provide radial confinement while end caps provide axial confinement. One of the ends is designed to allow passage of the soil into the fabric tube before sealing. Transportation requirements are reduced due to the low mass and volume of the fabric. Construction requirements are reduced due to the self-erection capability via the pneumatic exoskeleton. Maintenance requirements are reduced due to the passive nature of the concept. The structure's natural ductility is well suited for any seismic activity.
Cylindrical-shaped nanotube field effect transistor
Hussain, Muhammad Mustafa
2015-12-29
A cylindrical-shaped nanotube FET may be manufactured on silicon (Si) substrates as a ring etched into a gate stack and filled with semiconductor material. An inner gate electrode couples to a region of the gate stack inside the inner circumference of the ring. An outer gate electrode couples to a region of the gate stack outside the outer circumference of the ring. The multi-gate cylindrical-shaped nanotube FET operates in volume inversion for ring widths below 15 nanometers. The cylindrical-shaped nanotube FET demonstrates better short channel effect (SCE) mitigation and higher performance (I.sub.on/I.sub.off) than conventional transistor devices. The cylindrical-shaped nanotube FET may also be manufactured with higher yields and cheaper costs than conventional transistors.
Cylindrical-shaped nanotube field effect transistor
Hussain, Muhammad Mustafa; Fahad, Hossain M.; Smith, Casey E.; Rojas, Jhonathan Prieto
2015-01-01
A cylindrical-shaped nanotube FET may be manufactured on silicon (Si) substrates as a ring etched into a gate stack and filled with semiconductor material. An inner gate electrode couples to a region of the gate stack inside the inner circumference of the ring. An outer gate electrode couples to a region of the gate stack outside the outer circumference of the ring. The multi-gate cylindrical-shaped nanotube FET operates in volume inversion for ring widths below 15 nanometers. The cylindrical-shaped nanotube FET demonstrates better short channel effect (SCE) mitigation and higher performance (I.sub.on/I.sub.off) than conventional transistor devices. The cylindrical-shaped nanotube FET may also be manufactured with higher yields and cheaper costs than conventional transistors.
Micromagnetic simulations of cylindrical magnetic nanowires
Ivanov, Yurii P.; Chubykalo-Fesenko, O.
2015-01-01
This chapter reviews micromagnetic simulations of cylindrical magnetic nanowires and their ordered arrays. It starts with a description of the theoretical background of micromagnetism. The chapter discusses main magnetization reversal modes, domain
Plasma waves in an inhomogeneous cylindrical plasma
Pesic, S.S.
1976-01-01
The complete dispersion equation governing small amplitude plasma waves propagating in an inhomogeneous cylindrical plasma confined by a helical magnetic field is solved numerically. The efficiency of the wave energy thermalization in the lower hybrid frequency range is studied
Gravitational Instability of Cylindrical Viscoelastic Medium ...
similar to that of viscoelastic fluid where both properties work together. They also ... cylindrical gravitational waves provides a strong motivation in this regard. .... which represents the solenoidal character of the magnetic field and the total stress.
Analysis of Thermo-Acoustic Emission from Damage in Composite Laminates under Thermal Cyclic Loading
Kim, Young Bok; Min, Dae Hong; Lee, Deok Bo; Choi, Nak Sam
2001-01-01
An investigation on nondestructive evaluation of thermal stress-reduced damage in the composite laminates (3mm in thickness and [+45 6 /-45 6 ] S lay-up angles) has been performed using the thermo-acoustic emission technique. Reduction of thermo-AE events due to repetitive thermal load cycles showed a Kaiser effect. An analysis of the thermo-AE behavior determined the stress free temperature of composite laminates. Fiber fracture and matrix cracks were observed using the optical microscopy, scanning electron microscopy and ultrasonic C-sean. Short-Time Fourier Transform of thermo-AE signals offered the time-frequency characteristics which might classify the thermo-AE as three different types to estimate the damage processes of the composites
Equivalent circuit and optimum design of a multilayer laminated piezoelectric transformer.
Dong, Shuxiang; Carazo, Alfredo Vazquez; Park, Seung Ho
2011-12-01
A multilayer laminated piezoelectric Pb(Zr(1-x)Ti(x))O(3) (PZT) ceramic transformer, operating in a half- wavelength longitudinal resonant mode (λ/2 mode), has been analyzed. This piezoelectric transformer is composed of one thickness-polarized section (T-section) for exciting the longitudinal mechanical vibrations, two longitudinally polarized sections (L-section) for generating high-voltage output, and two insulating layers laminated between the T-section and L-section layers to provide insulation between the input and output sections. Based on the piezoelectric constitutive and motion equations, an electro-elasto-electric (EEE) equivalent circuit has been developed, and correspondingly, an effective EEE coupling coefficient was proposed for optimum design of this multilayer transformer. Commercial finite element analysis software is used to determine the validity of the developed equivalent circuit. Finally, a prototype sample was manufactured and experimental data was collected to verify the model's validity.
Determination of maximum negative Poisson's ratio for laminated fiber composites
Shokrieh, M.M.; Assadi, A. [Composites Research Laboratory, Mechanical Engineering Department, Center of Excellence in Experimental Solid Mechanics and Dynamics, Iran University of Science and Technology, Tehran 16846-13114 (Iran, Islamic Republic of)
2011-05-15
Contrary to isotropic materials, composites always show complicated mechanical behavior under external loadings. In this article, an efficient algorithm is employed to obtain the maximum negative Poisson's ratio for laminated composite plates. We try to simplify the problem based on normalization of parameters and some manufacturing constraints to overlook the additional constraint of the optimization procedure. A genetic algorithm is used to find the optimal thickness of each lamina with a specified fiber direction. It is observed that the laminated composite with the configuration of (15/60/15) has the maximum negative Poisson's ratio. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)
Effects of the shock duration on the response of CFRP composite laminates
Gay, Elise; Berthe, Laurent; Boustie, Michel; Arrigoni, Michel; Buzaud, Eric
2014-01-01
Shock loads induce a local tensile stress within a sample. The location and amplitude of this high strain rate stress can be monitored respectively by the duration and intensity of the shock. The process is applied to carbon fibre reinforced polymer (CFRP) composites, involved in aeronautic or defense industry. This paper describes the response of CFRP laminates of different thicknesses to a shock load normal to the fibres direction. The effects of the shock duration on the wave propagation are key issues of this work. Experiments have been performed on high power laser facilities and on a high power pulsed generator to get a wide range of pulse duration from fs to µs. Numerical simulation provides a comprehensive approach of the wave propagation and tensile stress generation within these complex materials. The main result concerns the relation between the load duration, the tensile stress and the induced delamination within 1, 4 and 8 ply composite laminates. (paper)
Chekhonin, Paul; Beausir, Benoît; Scharnweber, Juliane; Oertel, Carl-Georg; Hausöl, Tina; Höppel, Heinz Werner; Brokmeier, Heinz-Günter; Skrotzki, Werner
2012-01-01
Aluminium laminates consisting of high-purity aluminium and commercially pure aluminium have been produced by accumulative roll bonding (ARB) at ambient temperature for up to 10 cycles. To study the microstructure and texture development of the high-purity aluminium layers with regard to the shrinking layer thickness during ARB, microstructure and texture investigations were carried out by electron backscatter diffraction and neutron and X-ray diffraction, respectively. While the commercially pure aluminium layers develop an ultrafine-grained microstructure, partial discontinuous recrystallization occurs in the high-purity layers. The texture of the high-purity layers mainly consists of Cube and “Tilted Cube” (tilted with respect to the transverse direction) components. The experimental results are discussed with respect to confined recrystallization in the ARB aluminium laminates.
Radon progeny distribution in cylindrical diffusion chambers
Pressyanov, Dobromir S.
2008-01-01
An algorithm to model the diffusion of radioactive decay chain atoms is presented. Exact mathematical solutions in cylindrical geometry are given. They are used to obtain expressions for the concentrations of 222 Rn progeny atoms in the volume and deposited on the wall surface in cylindrical diffusion chambers. The dependence of volume fractions of 222 Rn progeny and chamber sensitivity on the coefficient of diffusion of 222 Rn progeny atoms in air is modeled.
Cylindrical geometry for proportional and drift chambers
Sadoulet, B.
1975-06-01
For experiments performed around storage rings such as e + e - rings or the ISR pp rings, cylindrical wire chambers are very attractive. They surround the beam pipe completely without any dead region in the azimuth, and fit well with the geometry of events where particles are more or less spherically produced. Unfortunately, cylindrical proportional or drift chambers are difficult to make. Problems are discussed and two approaches to fabricating the cathodes are discussed. (WHK)
Cylindrical dust acoustic waves with transverse perturbation
Xue Jukui
2003-01-01
The nonlinear dust acoustic waves in dusty plasmas with the combined effects of bounded cylindrical geometry and the transverse perturbation are studied. Using the perturbation method, a cylindrical Kadomtsev-Petviashvili (CKP) equation that describes the dust acoustic waves is deduced for the first time. A particular solution of this CKP equation is also obtained. It is shown that the dust acoustic solitary waves can exist in the CKP equation
Effect of Electrospun Nanofibers on the Short Beam Strength of Laminated Fiberglass Composite
Shinde, Dattaji K.
High specific modulus and strength are the most desirable properties for the material used in structural applications. Composite materials exhibit these properties and over the last decade, their usage has increased significantly, particularly in automotive, defense, and aerospace applications. The major cause of failures in composite laminates is due to delaminations. Delamination in composite laminates can occur due to fatigue, low velocity impact and other loadings modes. Conventional methods like "through-the-thickness stitching" or "Z-Pinning" have limitations for improving flexural and interlaminar properties in woven composites due to the fact that while improving interlaminar properties, the presence of stitches or Z pins affects in-plane properties. This study investigates the flexural behavior of fiberglass composites interleaved with non-woven Tetra Ethyl Orthosilicate (TEOS) electrsopsun nanofibers (ENFs). TEOS ENFs were manufactured using an electrospinning technique and then sintered. Nanoengineered beams were fabricated by interleaving TEOS ENFs between the laminated fiberglass composites to improve the flexural properties. TEOS ENFs, resin film, and failed fiberglass laminated composites with and without nanofibers were characterized using SEM Imaging and ASTM standard testing methods. A hybrid composite was made by interleaving a non-woven sheet of TEOS ENFs between the fiberglass laminates with additional epoxy resin film and fabricated using the out of autoclave vacuum bagging method. Four commonly used stacking sequences of fiberglass laminates with and without nanofibers were used to study the progressive failure and deformation mechanics under flexural loadings. The experimental study has shown significant improvements in short beam strength and strain energy absorption in the nanoengineered laminated fiberglass composites before complete failure. The modes were investigated by performing detailed fractographic examination of failed specimens
The Pulsed Cylindrical Magnetron for Deposition
Korenev, Sergey
2012-10-01
The magnetron sputtering deposition of films and coatings broadly uses in microelectronics, material science, environmental applications and etc. The rate of target evaporation and time for deposition of films and coatings depends on magnetic field. These parameters link with efficiency of gas molecules ionization by electrons. The cylindrical magnetrons use for deposition of films and coatings on inside of pipes for different protective films and coatings in oil, chemical, environmental applications. The classical forming of magnetic field by permanent magnets or coils for big and long cylindrical magnetrons is complicated. The new concept of pulsed cylindrical magnetron for high rate deposition of films and coating for big and long pipes is presented in this paper. The proposed cylindrical magnetron has azimuthally pulsed high magnetic field, which allows forming the high ionized plasma and receiving high rate of evaporation material of target (central electrode). The structure of proposed pulsed cylindrical magnetron sputtering system is given. The main requirements to deposition system are presented. The preliminary data for forming of plasma and deposition of Ta films and coatings on the metal pipers are discussed. The comparison of classical and proposed cylindrical magnetrons is given. The analysis of potential applications is considered.
Effects of stitching on fracture toughness of uniweave textile graphite/epoxy laminates
Sankar, Bhavani V.; Sharma, Suresh
1995-01-01
The effects of through-the-thickness stitching on impact damage resistance, impact damage tolerance, and Mode 1 and Mode 2 fracture toughness of textile graphite/epoxy laminates were studied experimentally. Graphite/epoxy laminates were fabricated from AS4 graphite uniweave textiles and 3501-6 epoxy using Resin Transfer Molding. The cloths were stitched with Kevlar(tm) and glass yarns before resin infusion. Delamination was implanted during processing to simulate impact damage. Sublaminate buckling tests were performed in a novel fixture to measure Compression After Impact (CAI) strength of stitched laminates. The results show that CAI strength can be improved up to 400% by through-the-thickness stitching. Double Cantilever Beam tests were performed to study the effect of stitching on Mode 1 fracture toughness G(sub 1c). It was found that G(sub 1c) increased 30 times for a low stitching density of 16 stitches/sq in. Mode 2 fracture toughness was measured by testing the stitched beams in End Notch Flexure tests. Unlike in the unstitiched beams, crack propagation in the stitched beams was steady. The current formulas for ENF tests were not found suitable for determining G(sub 2C) for stitched beams. Hence two new methods were developed - one based on crack area measured from ultrasonic C-scanning and the other based on equivalent crack area measured from the residual stiffness of the specimen. The G(sub 2c) was found to be at least 5-15 times higher for the stitched laminates. The mechanisms by which stitching increases the CAI strength and fracture toughness are discussed.
Frequency response analysis of cylindrical shells conveying fluid using finite element method
Seo, Young Soo; Jeong, Weui Bong; Yoo, Wan Suk; Jeong, Ho Kyeong
2005-01-01
A finite element vibration analysis of thin-walled cylindrical shells conveying fluid with uniform velocity is presented. The dynamic behavior of thin-walled shell is based on the Sanders' theory and the fluid in cylindrical shell is considered as inviscid and incompressible so that it satisfies the Laplace's equation. A beam-like shell element is used to reduce the number of degree-of-freedom by restricting to the circumferential modes of cylindrical shell. An estimation of frequency response function of the pipe considering of the coupled effects of the internal fluid is presented. A dynamic coupling condition of the interface between the fluid and the structure is used. The effective thickness of fluid according to circumferential modes is also discussed. The influence of fluid velocity on the frequency response function is illustrated and discussed. The results by this method are compared with published results and those by commercial tools
Accelerating Thick Aluminum Liners Using Pulsed Power
Kyrala, G.A.; Hammerburg, J.E.; Bowers, D.; Stokes, J.; Morgan, D.V.; Anderson, W.E.; Cochrane, J.C.
1999-01-01
The authors have investigated the acceleration of very thick cylindrical aluminum liners using the Pegasus II capacitory bank. These accelerated solid liners will be used to impact other objects at velocities below 1.5 km/sec, allowing one to generate and sustain shocks of a few 100 kilobar for a few microseconds. A cylindrical shell of 1100 series aluminum with an initial inner radius of 23.61 mm, an initial thickness of 3.0 mm, and a height of 20 mm, was accelerated using a current pulse of 7.15 MA peak current and a 7.4 microsecond quarter cycle time. The aluminum shell was imploded within confining copper glide planes with decreasing separation with an inward slope of 8 degrees. At impact with a cylindrical target of diameter 3-cm, the liner was moving at 1.4 km/sec and its thickness increased to 4.5 mm. Radial X-ray radiograms of the liner showed both the liner and the glide plane interface. The curvature of the inner surface of the liner was measured before impact with the 15-mm radius target. The radiograms also showed that the copper glide planes distorted as the liner radius decreased and that some axial stress is induced in the liner. The axial stresses did not affect the inner curvature significantly. Post-shot calculations of the liner behavior indicated that the thickness of the glide plane played a significant role in the distortion of the interface between the liner and the glide plane
Fatigue and fracture of fibre metal laminates
Alderliesten, René
2017-01-01
This book contributes to the field of hybrid technology, describing the current state of knowledge concerning the hybrid material concept of laminated metallic and composite sheets for primary aeronautical structural applications. It is the only book to date on fatigue and fracture of fibre metal laminates (FMLs). The first section of the book provides a general background of the FML technology, highlighting the major FML types developed and studied over the past decades in conjunction with an overview of industrial developments based on filed patents. In turn, the second section discusses the mechanical response to quasi-static loading, together with the fracture phenomena during quasi-static and cyclic loading. To consider the durability aspects related to strength justification and certification of primary aircraft structures, the third section discusses thermal aspects related to FMLs and their mechanical response to various environmental and acoustic conditions.
Prediction of fatigue damage in tapered laminates
Raeis Hosseiny, Seyed Aydin; Jakobsen, Johnny
2017-01-01
Effective implementation of ply-drops configurations substantially improve the damage tolerant design of flexible and aero-elastic wind turbine blades. Terminating a number of layers for an optimized blade design creates local bending effects. Inter-laminar stress states in tapered areas give rise...... to delamination and premature structural failure. Precise calculation of the stress levels for embedded ply-drops is required to predict failure initiation within acceptable limits. Multi-axial stress states in orthotropic laminates subjected to diverse loading mechanisms nucleate microscopic cracks....... By increasing the cracks density, damage occurs when residual material properties reduce to a critical level. Residual strength and stiffness of simple laminates are assigned in a set of fatigue failure criteria to assess the remaining life of the components by increasing number of loading cycles. The mode...
Fabrication of CFRP/Al Active Laminates
Asanuma, Hiroshi; Haga, Osamu; Ohira, Junichiro; Takemoto, Kyosuke; Imori, Masataka
This paper describes fabrication and evaluation of the active laminate. It was made by hot-pressing of an aluminum plate as a high CTE material, a unidirectional CFRP prepreg as a low CTE material and an electric resistance heater, a KFRP prepreg as a low CTE material and an insulator between them, and copper foils as electrodes. In this study, fabricating conditions and performances such as curvature change and output force were examined. Under optimized fabricating conditions, it became clear that 1) the curvature of the active laminate linearly changes as a function of temperature, between room temperature and its hot pressing temperature without hysteresis by electric resistance heating of carbon fiber in the CFRP layer and cooling, and 2) the output force against a fixed punch almost linearly increases with increasing temperature during heating from 313K up to around the glass transition temperature of the epoxy matrix.
Process simulations for manufacturing of thick composites
Kempner, Evan A.
The availability of manufacturing simulations for composites can significantly reduce the costs associated with process development. Simulations provide a tool for evaluating the effect of processing conditions on the quality of parts produced without requiring numerous experiments. This is especially significant in parts that have troublesome features such as large thickness. The development of simulations for thick walled composites has been approached by examining the mechanics of resin flow and fiber deformation during processing, applying these evaluations to develop simulations, and evaluating the simulation with experimental results. A unified analysis is developed to describe the three-dimensional resin flow and fiber preform deformation during processing regardless of the manufacturing process used. It is shown how the generic governing evaluations in the unified analysis can be applied to autoclave molding, compression molding, pultrusion, filament winding, and resin transfer molding. A comparison is provided with earlier models derived individually for these processes. The evaluations described for autoclave curing were used to produce a one-dimensional cure simulation for autoclave curing of thick composites. The simulation consists of an analysis for heat transfer and resin flow in the composite as well as bleeder plies used to absorb resin removed from the part. Experiments were performed in a hot press to approximate curing in an autoclave. Graphite/epoxy laminates of 3 cm and 5 cm thickness were cured while monitoring temperatures at several points inside the laminate and thickness. The simulation predicted temperatures fairly closely, but difficulties were encountered in correlation of thickness results. This simulation was also used to study the effects of prepreg aging on processing of thick composites. An investigation was also performed on filament winding with prepreg tow. Cylinders were wound of approximately 12 mm thickness with pressure
Numerical analysis of laminated elastomer by FEM
Mazda, T.; Shiojiri, H.
1993-01-01
A Computer code based on mixed finite element method was developed for three dimensional large strain analyses of laminated elastomers including nonlinear bulk stress vs. bulk strain relationships. The adopted element is the variable node element with maximum node numbers of 27 for displacements and 4 for pressures. At first, the displacements and pressures were calculated by the code using single element under various loading conditions. The results were compared with theoretical solutions and the both results' exactly coincided with each other. Next, the analyses of laminated elastomers subjected to axial loadings were conducted using both the new code and ABAQUS code, and the results were compared with the test results. The agreement of the results of the present code were better than ABAQUS code mainly due to the capability of handling wider range of material properties. Lastly, the shearing tests of laminated elastomers were simulated by the new code. The results were shown to be in good agreement with the test results. (author)
Local and global Casimir energies for a semitransparent cylindrical shell
Cavero-Pelaez, Ines; Milton, Kimball A; Kirsten, Klaus
2007-01-01
The local Casimir energy density and the global Casimir energy for a massless scalar field associated with a λδ-function potential in a (3 + 1)-dimensional circular cylindrical geometry are considered. The global energy is examined for both weak and strong coupling, the latter being the well-studied Dirichlet cylinder case. For weak coupling, through O(λ 2 ), the total energy is shown to vanish by both analytic and numerical arguments, based both on Green's-function and zeta-function techniques. Divergences occurring in the calculation are shown to be absorbable by renormalization of physical parameters of the model. The global energy may be obtained by integrating the local energy density only when the latter is supplemented by an energy term residing precisely on the surface of the cylinder. The latter is identified as the integrated local energy density of the cylindrical shell when the latter is physically expanded to have finite thickness. Inside and outside the δ-function shell, the local energy density diverges as the surface of the shell is approached; the divergence is weakest when the conformal stress tensor is used to define the energy density. A real global divergence first occurs in O(λ 3 ), as anticipated, but the proof is supplied here for the first time; this divergence is entirely associated with the surface energy and does not reflect divergences in the local energy density as the surface is approached
Explosion-Induced Implosions of Cylindrical Shell Structures
Ikeda, C. M.; Duncan, J. H.
2010-11-01
An experimental study of the explosion-induced implosion of cylindrical shell structures in a high-pressure water environment was performed. The shell structures are filled with air at atmospheric pressure and are placed in a large water-filled pressure vessel. The vessel is then pressurized to various levels P∞=αPc, where Pc is the natural implosion pressure of the model and α is a factor that ranges from 0.1 to 0.9. An explosive is then set off at various standoff distances, d, from the model center line, where d varies from R to 10R and R is the maximum radius of the explosion bubble. High-speed photography (27,000 fps) was used to observe the explosion and resulting shell structure implosion. High-frequency underwater blast sensors recorded dynamic pressure waves at 6 positions. The cylindrical models were made from aluminum (diameter D = 39.1 mm, wall thickness t = 0.89 mm, length L = 240 mm) and brass (D = 16.7 mm, t = 0.36 mm, L=152 mm) tubes. The pressure records are interpreted in light of the high-speed movies. It is found that the implosion is induced by two mechanisms: the shockwave generated by the explosion and the jet formed during the explosion-bubble collapse. Whether an implosion is caused by the shockwave or the jet depends on the maximum bubble diameter and the standoff distance.
Implosion of Cylindrical Cavities via Short Duration Impulsive Loading
Huneault, Justin; Higgins, Andrew
2014-11-01
An apparatus has been developed to study the collapse of a cylindrical cavity in gelatin subjected to a symmetric impact-driven impulsive loading. A gas-driven annular projectile is accelerated to approximately 50 m/s, at which point it impacts a gelatin casting confined by curved steel surfaces that allow a transition from an annular geometry to a cylindrically imploding motion. The implosion is visualized by a high-speed camera through a window which forms the top confining wall of the implosion cavity. The initial size of the cavity is such that the gelatin wall is two to five times thicker than the impacting projectile. Thus, during impact the compression wave which travels towards the cavity is closely followed by a rarefaction resulting from the free surface reflection of the compression wave in the projectile. As the compression wave in the gelatin reaches the inner surface, it will also reflect as a rarefaction wave. The interaction between the rarefaction waves from the gelatin and projectile free surfaces leads to large tensile stresses resulting in the spallation of a relatively thin shell. The study focuses on the effect of impact parameters on the thickness and uniformity of the imploding shell formed by the cavitation in the imploding gelatin cylinder.
Nonlinear Vibration and Mode Shapes of FG Cylindrical Shells
Saeed Mahmoudkhani
Full Text Available Abstract The nonlinear vibration and normal mode shapes of FG cylindrical shells are investigated using an efficient analytical method. The equations of motion of the shell are based on the Donnell’s non-linear shallow-shell, and the material is assumed to be gradually changed across the thickness according to the simple power law. The solution is provided by first discretizing the equations of motion using the multi-mode Galerkin’s method. The nonlinear normal mode of the system is then extracted using the invariant manifold approach and employed to decouple the discretized equations. The homotopy analysis method is finally used to determine the nonlinear frequency. Numerical results are presented for the backbone curves of FG cylindrical shells, nonlinear mode shapes and also the nonlinear invariant modal surfaces. The volume fraction index and the geometric properties of the shell are found to be effective on the type of nonlinear behavior and also the nonlinear mode shapes of the shell. The circumferential half-wave numbers of the nonlinear mode shapes are found to change with time especially in a thinner cylinder.
Understanding the edge crack phenomenon in ceramic laminates
O. Ševeček
2015-10-01
Full Text Available Layered ceramic materials (also referred to as “ceramic laminates” are becoming one of the most promising areas of materials technology aiming to improve the brittle behavior of bulk ceramics. The utilization of tailored compressive residual stresses acting as physical barriers to crack propagation has already succeeded in many ceramic systems. Relatively thick compressive layers located below the surface have proven very effective to enhance the fracture resistance and provide a minimum strength for the material. However, internal compressive stresses result in out-of plane stresses at the free surfaces, what can cause cracking of the compressive layer, forming the so-called edge cracks. Experimental observations have shown that edge cracking may be associated with the magnitude of the compressive stresses and with the thickness of the compressive layer. However, an understanding of the parameters related to the onset and extension of such edge cracks in the compressive layers is still lacking. In this work, a 2D parametric finite element model has been developed to predict the onset and propagation of an edge crack in ceramic laminates using a coupled stress-energy criterion. This approach states that a crack is originated when both stress and energy criteria are fulfilled simultaneously. Several designs with different residual stresses and a given thickness in the compressive layers have been computed. The results predict the existence of a lower bound, below no edge crack will be observed, and an upper bound, beyond which the onset of an edge crack would lead to the complete fracture of the layer
Verification and Validation of Carbon-Fiber Laminate Low Velocity Impact Simulations.
English, Shawn Allen; Nelson, Stacy Michelle; Briggs, Timothy; Brown, Arthur A.
2014-10-01
Presented is a model verification and validation effort using low - velocity impact (LVI) of carbon fiber reinforced polymer laminate experiments. A flat cylindrical indenter impacts the laminate with enough energy to produce delamination, matrix cracks and fiber breaks. Included in the experimental efforts are ultrasonic scans of the damage for qualitative validation of the models. However, the primary quantitative metrics of validation are the force time history measured through the instrumented indenter and initial and final velocities. The simulations, whi ch are run on Sandia's Sierra finite element codes , consist of all physics and material parameters of importance as determined by a sensitivity analysis conducted on the LVI simulation. A novel orthotropic damage and failure constitutive model that is cap able of predicting progressive composite damage and failure is described in detail and material properties are measured, estimated from micromechanics or optimized through calibration. A thorough verification and calibration to the accompanying experiment s are presented. Specia l emphasis is given to the four - point bend experiment. For all simulations of interest, the mesh and material behavior is verified through extensive convergence studies. An ensemble of simulations incorporating model parameter unc ertainties is used to predict a response distribution which is then compared to experimental output. The result is a quantifiable confidence in material characterization and model physics when simulating this phenomenon in structures of interest.
Design Investigation of a Laminated Waveguide Fed Multi-Band DRA for Military Applications
Kumar, Pramod; Dwari, Santanu; Singh, Shailendra; Agrawal, N. K.
2017-12-01
In this paper a laminated waveguide fed DR Antenna is investigated. It can use for moderate power military applications. Cylindrical DRA is excited by two closely spaced asymmetric longitudinal slots on the broad wall of the laminated cavity are responsible for producing three different frequency bands. Parametric study of slots has been done with the help of commercial software ANSOFT HFSS. All the bands have sharp rejection. The final model of the antenna is simulated, fabricated and experimentally measured. Measured results are in quite accordant with design results. SIW feeding structures have small losses, moderate power handling capacity, low costs, compact sizes and can be seamlessly integrated with planar circuits. At all the bands 9.76 GHz, 10.53 GHz and 11.8 GHz resonant frequency, the antenna shows 56 MHz, 160 MHz, and 250 MHz impedance bandwidth (for VSWR<2) with 6 dB,6.2 dB and 6.8 dB gain respectively. Simulated and measured results reveal outstanding performance with a cross-polar level of 29 dB lower than that of the co-polar level at 9.76 GHz, the cross-polar level of 32 dB lower than that of the co-polar level at 10.53, GHz, and similarly cross-polar level of 30 dB lower than that of the co-polar level at 11.8 GHz.
Circumferential buckling instability of a growing cylindrical tube
Moulton, D.E.
2011-03-01
A cylindrical elastic tube under uniform radial external pressure will buckle circumferentially to a non-circular cross-section at a critical pressure. The buckling represents an instability of the inner or outer edge of the tube. This is a common phenomenon in biological tissues, where it is referred to as mucosal folding. Here, we investigate this buckling instability in a growing elastic tube. A change in thickness due to growth can have a dramatic impact on circumferential buckling, both in the critical pressure and the buckling pattern. We consider both single- and bi-layer tubes and multiple boundary conditions. We highlight the competition between geometric effects, i.e. the change in tube dimensions, and mechanical effects, i.e. the effect of residual stress, due to differential growth. This competition can lead to non-intuitive results, such as a tube growing to be thinner and yet buckle at a higher pressure. © 2011 Elsevier Ltd. All rights reserved.
Arteriographical and pathological changes in chronic laminitis in dairy cattle.
Boosman, R; Nemeth, F; Gruys, E; Klarenbeek, A
1989-07-01
The arteriographic appearance of 76 bovine hind digits, obtained from a slaughterhouse, was related to the macroscopic signs of chronic laminitis in the digits. There were statistically significant correlations between the macroscopic and the arteriographic appearance of the claws. Subsequent histological examination of the radiographically abnormal arteries revealed features indicative of arteriosclerosis. The results of this study indicate that chronic laminitis develops following a subclinical attack of laminitis due to a continous hypoperfusion of the digit.
Energy Saving Glass Lamination via Selective Radio-Frequency Heating
Shulman, Holly S.; Allan, Shawn M.
2009-11-11
This Inventions and Innovations program supported the technical and commercial research and development needed to elevate Ceralink's energy saving process for flat glass lamination from bench scale to a self-supporting technology with significant potential for growth. Radio-frequency heating was any un-explored option for laminating glass prior to this program. With significant commercial success through time and energy savings in the wood, paper, and plastics industries, RF heating was found to have significant promise for the energy intensive glass lamination industry. A major technical goal of the program was to demonstrate RF lamination across a wide range of laminate sizes and materials. This was successfully accomplished, dispelling many skeptics' concerns about the abilities of the technology. Ceralink laminated panels up to 2 ft x 3 ft, with four sets processed simultaneously, in a 3 minute cycle. All major categories of interlayer materials were found to work with RF lamination. In addition to laminating glass, other materials including photovoltaic silicon solar cells, light emitting diodes, metallized glass, plastics (acrylic and polycarbonate), and ceramics (alumina) were found compatible with the RF process. This opens up a wide range of commercial opportunities beyond the initially targeted automotive industry. The dramatic energy savings reported for RF lamination at the bench scale were found to be maintained through the scale up of the process. Even at 2 ft x 3 ft panel sizes, energy savings are estimated to be at least 90% compared to autoclaving or vacuum lamination. With targeted promotion through conference presentations, press releases and internet presence, RF lamination has gained significant attention, drawing large audiences at American Ceramic Society meetings. The commercialization success of the project includes the establishment of a revenue-generating business model for providing process development and demonstrations for
Simulation of temperature distribution in cylindrical and prismatic lithium ion secondary batteries
Inui, Y.; Kobayashi, Y.; Watanabe, Y.; Watase, Y.; Kitamura, Y.
2007-01-01
The authors develop two-dimensional and three-dimensional simulation codes of the transient response of the temperature distribution in the lithium ion secondary battery during a discharge cycle. At first, a two-dimensional simulation code for a cylindrical battery is developed, and the simulation results for a commercially available small size battery are compared with the corresponding experimental results. The simulation results of the transient temperature and voltage variations coincide very well with the experimental results. The simulation result of the temperature difference between the center of the battery body and the center of the battery side is also in reasonable agreement with the experimental result. Next, the authors develop a three-dimensional simulation code and perform numerical simulations for three large size prismatic batteries with the same capacity and different cross sectional shapes. It is made clear that selecting the battery with the laminated cross section has a remarkable effect on the suppression of the temperature rise in comparison with the battery with square cross section, whereas the effect of the lamination on the suppression of the temperature unevenness is unexpectedly small. These results indicate the accuracy and usefulness of the developed simulation codes
Minimization of stress concentration factor in cylindrical pressure vessels with ellipsoidal heads
Magnucki, K.; Szyc, W.; Lewinski, J.
2002-01-01
The paper presents the problem of stress concentration in a cylindrical pressure vessel with ellipsoidal heads subject to internal pressure. At the line, where the ellipsoidal head is adjacent to the circular cylindrical shell, a shear force and bending moment occur, disturbing the membrane stress state in the vessel. The degree of stress concentration depends on the ratio of thicknesses of both the adjacent parts of the shells and on the relative convexity of the ellipsoidal head, with the range for radius-to-thickness ratio between 75 and 125. The stress concentration was analytically described and, afterwards, the effect of these values on the stress concentration ratio was numerically examined. Results of the analysis are shown on charts
K.P. Pradhan
2015-12-01
Full Text Available In this paper, an analytical threshold voltage model is proposed for a cylindrical gate-all-around (CGAA MOSFET by solving the 2-D Poisson’s equation in the cylindrical coordinate system. A comparison is made for both the center and the surface potential model of CGAA MOSFET. This paper claims that the calculation of threshold voltage using center potential is more accurate rather than the calculation from surface potential. The effects of the device parameters like the drain bias (VDS, oxide thickness (tox, channel thickness (r, etc., on the threshold voltage are also studied in this paper. The model is verified with 3D numerical device simulator Sentaurus from Synopsys Inc.
Energy Saving Glass Lamination via Selective Radio Frequency Heating
Allan, Shawn M; Baranova, Inessa; Poley, Joseph; Reis, Henrique
2012-02-27
This project focused on advancing radio-frequency (RF) lamination technology closer to commercial implementation, in order to reduce the energy intensity of glass lamination by up to 90%. Lamination comprises a wide range of products including autoglass, architectural safety and innovative design glass, transparent armor (e.g. bullet proof glass), smart glass, mirrors, and encapsulation of photovoltaics. Lamination is also the fastest growing segment of glass manufacturing, with photovoltaics, architectural needs, and an anticipated transition to laminated side windows in vehicles. The state-of-the-art for glass lamination is to use autoclaves, which apply heat and uniform gas pressure to bond the laminates over the course of 1 to 18 hours. Laminates consist of layers of glass or other materials bonded with vinyl or urethane interlayers. In autoclaving, significant heat energy is lost heating the chamber, pressurized air, glass racks, and the glass. In RF lamination, the heat is generated directly in the vinyl interlayer, causing it to heat and melt quickly, in just 1 to 10 minutes, without significantly heating the glass or the equipment. The main purpose of this project was to provide evidence that low energy, rapid RF lamination quality met the same standards as conventionally autoclaved windows. The development of concepts for laminating curved glass with RF lamination was a major goal. Other primary goals included developing a stronger understanding of the lamination product markets described above, and to refine the potential benefits of commercial implementation. The scope of the project was to complete implementation concept studies in preparation for continuation into advanced development, pilot studies, and commercial implementation. The project consisted of 6 main tasks. The first dealt with lamination with poly-vinyl butyral (PVB) interlayers, which prior work had shown difficulties in achieving good quality laminates, working with Pilkington North
Energy Saving Glass Lamination via Selective Radio Frequency Heating
Allan, Shawn M.
2012-02-27
This project focused on advancing radio-frequency (RF) lamination technology closer to commercial implementation, in order to reduce the energy intensity of glass lamination by up to 90%. Lamination comprises a wide range of products including autoglass, architectural safety and innovative design glass, transparent armor (e.g. bullet proof glass), smart glass, mirrors, and encapsulation of photovoltaics. Lamination is also the fastest growing segment of glass manufacturing, with photovoltaics, architectural needs, and an anticipated transition to laminated side windows in vehicles. The state-of-the-art for glass lamination is to use autoclaves, which apply heat and uniform gas pressure to bond the laminates over the course of 1 to 18 hours. Laminates consist of layers of glass or other materials bonded with vinyl or urethane interlayers. In autoclaving, significant heat energy is lost heating the chamber, pressurized air, glass racks, and the glass. In RF lamination, the heat is generated directly in the vinyl interlayer, causing it to heat and melt quickly, in just 1 to 10 minutes, without significantly heating the glass or the equipment. The main purpose of this project was to provide evidence that low energy, rapid RF lamination quality met the same standards as conventionally autoclaved windows. The development of concepts for laminating curved glass with RF lamination was a major goal. Other primary goals included developing a stronger understanding of the lamination product markets described above, and to refine the potential benefits of commercial implementation. The scope of the project was to complete implementation concept studies in preparation for continuation into advanced development, pilot studies, and commercial implementation. The project consisted of 6 main tasks. The first dealt with lamination with poly-vinyl butyral (PVB) interlayers, which prior work had shown difficulties in achieving good quality laminates, working with Pilkington North
Current perpendicular to plane giant magnetoresistance in laminated nanostructures
Vedyayev, A.; Zhukov, I.; Dieny, B.
2005-01-01
We theoretically studied spin-dependent electron transport perpendicular-to-plain (CPP) in magnetic laminated multilayered structures by using Kubo formalism. We took into account not only bulk scattering, but the interface resistance due to both specular and diffuse reflection and also spin conserving and spin-flip processes. It was shown that spin-flip scattering at interfaces substantially reduces the value of giant magnetoresistance (GMR). This can explain the experimental observations that the CPP GMR ratio for laminated structures only slightly increases as compared to non-laminated ones even though lamination induces a significant increase in CPP resistance
Forced vibrations of rotating circular cylindrical shells
Igawa, Hirotaka; Maruyama, Yoshiyuki; Endo, Mitsuru
1995-01-01
Forced vibrations of rotating circular cylindrical shells are investigated. Basic equations, including the effect of initial stress due to rotation, are formulated by the finite-element method. The characteristic relations for finite elements are derived from the energy principle by considering the finite strain. The equations of motion can be separated into quasi-static and dynamic ones, i.e., the equations in the steady rotating state and those in the vibration state. Radial concentrated impulses are considered as the external dynamic force. The transient responses of circular cylindrical shells are numerically calculated under various boundary conditions and rotating speeds. (author)
Scattering of spermatozoa off cylindrical pillars
Bukatin, Anton; Lushi, Enkeleida; Kantsler, Vasily
2017-11-01
The motion of micro-swimmers in structured environments, even though crucial in processes such as in vivo and in vitro egg fertilization, is still not completely understood. We combine microfluidic experiments with mathematical modeling of 3D swimming near convex surfaces to quantify the dynamics of individual sperm cells in the proximity of cylindrical pillars. Our results show that the hydrodynamic and contact forces that account for the shape asymmetry and flagellar motion, are crucial in correctly describing the dynamics observed in the experiments. Last, we discuss how the size of the cylindrical obstacles determines whether the swimmers scatter off or get trapped circling the pillar.
Micromagnetic simulations of cylindrical magnetic nanowires
Ivanov, Yurii P.
2015-05-27
This chapter reviews micromagnetic simulations of cylindrical magnetic nanowires and their ordered arrays. It starts with a description of the theoretical background of micromagnetism. The chapter discusses main magnetization reversal modes, domain wall types, and state diagrams in cylindrical nanowires of different types and sizes. The results of the hysteresis process in individual nanowires and nanowire arrays also are presented. Modeling results are compared with experimental ones. The chapter also discusses future trends in nanowire applications in relation to simulations, such as current-driven dynamics, spintronics, and spincaloritronics. The main micromagnetic programs are presented and discussed, together with the corresponding links.
Cylindrical concave body of composite fibrous material
1979-01-01
The invention is concerned with a cylindrical concave body of compound fibrous material which is intended to be exposed to high rotation speeds around its own longitudinal axis. The concave body in question has at least one layer of fibrils that are interwoven and enclose an identical angle with the longitudinal axis of the concave body in both directions. The concave body in question also has at least a second layer of fibrils that run in the direction of the circumference and are fitted radially to the outside. The cylindrical concave body of the invention is particularly well suited for application as a rotor tube in a gas ultra-centrifuge
Cylindrical pressure vessel constructed of several layers
Yamauchi, Takeshi.
1976-01-01
For a cylindrical pressure vessel constructed of several layers whose jacket has at least one circumferential weld joining the individual layers, it is proposed to provide this at least at the first bending line turning point (counting from the weld between the jacket and vessel floor), which the sinusoidally shaped jacket has. The section of the jacket extending in between should be made as a full wall section. The proposal is based on calculations of the bending stiffness of cylindrical jackets, which could not yet be confirmed for jackets having several layers. (UWI) [de
Magnetic guns with cylindrical permanent magnets
Vokoun, David; Beleggia, Marco; Heller, Luděk
2012-01-01
The motion of a cylindrical permanent magnet (projectile) inside a tubular permanent magnet, with both magnets magnetized axially, illustrates nicely the physical principles behind the operation of magnetic guns. The force acting upon the projectile is expressed semi-analytically as derivative...... of the magnetostatic interaction energy. For comparison, the forces involved are also calculated numerically using finite elements methods. Based on the conservation of the magnetostatic and kinetic energies, the exit and asymptotic velocities are determined. The derived formulas can be used to optimize the generated...... forces and motion of the inner cylindrical magnet....
American Society for Testing and Materials. Philadelphia
2004-01-01
1.1 This test method covers the determination of translaminar fracture toughness, KTL, for laminated and pultruded polymer matrix composite materials of various ply orientations using test results from monotonically loaded notched specimens. 1.2 This test method is applicable to room temperature laboratory air environments. 1.3 Composite materials that can be tested by this test method are not limited by thickness or by type of polymer matrix or fiber, provided that the specimen sizes and the test results meet the requirements of this test method. This test method was developed primarily from test results of various carbon fiber – epoxy matrix laminates and from additional results of glass fiber – epoxy matrix, glass fiber-polyester matrix pultrusions and carbon fiber – bismaleimide matrix laminates (1-4, 6, 7). 1.4 A range of eccentrically loaded, single-edge-notch tension, ESE(T), specimen sizes with proportional planar dimensions is provided, but planar size may be variable and adjusted, with asso...
Process monitoring of glass reinforced polypropylene laminates using fiber Bragg gratings
Mulle, Matthieu
2015-12-29
Hot-press molding of glass-fiber-reinforced polypropylene (GFPP) laminates was monitored using longitudinally and transversely embedded fiber Bragg gratings (FBGs) at different locations in unidirectional laminates. The optical sensors proved to efficiently characterize some material properties; for example, strain variations could be related physical change of the laminate, revealing key transition points such as the onset of melt or solidification. These results were confirmed through some comparison with traditional techniques such as differential scanning calorimetry. After the GFPP plate was released from the mold, residual strains were estimated. Because cooling rate is an important process parameter in thermoplastics, affecting crystallinity and ultimately residual strain, two different conditions (22 and 3 °C/min) were investigated. In the longitudinal direction, results were nearly identical while in the transverse direction results showed a 20% discrepancy. Coefficients of thermal expansion (CTE) were also identified during a post-process heating procedure using the embedded FBGs and compared to the results of a thermo-mechanical analysis. Again, dissimilarities were observed for the transverse direction. With regards to through the thickness properties, no differences were observed for residual strains or for CTEs.
Investigation of actuator debonding effects on active control in smart composite laminates
Bin Huang
2015-04-01
Full Text Available This article presents a numerical study of active vibration control of smart composite laminates in the presence of actuator debonding failures. A comparison between the smart composite laminates with healthy actuator and various partially debonded actuator cases is performed to investigate the debonding effects on the vibration suppression. The improved layerwise theory with Heaviside’s unit step function is adopted to model the displacement field with actuator debonding failure. The higher order electric potential field is adopted to describe the potential variation through the thickness. The finite element method–based formulations are derived using the plate element, taking into consideration the electro-mechanical coupling effect. The reduced-order model is represented by the state-space form and further for the vibration suppression using a simple constant gain velocity feedback control strategy. For the purpose of demonstration, a 16-layer cross-ply substrate laminate ([0/90]4s is employed for the numerical study. The results show that the actuator debonding affects the closed-loop frequencies, active damping ratios, and efficiency of vibration suppression.
B. E. B. Uribe
2017-01-01
Full Text Available In this paper, a cost-effective and eco-friendly method to improve mechanical performance in continuous carbon fiber-reinforced polymer (CFRP matrix composites is presented. Unsized fiber fabric preforms are coated with self-assembling sugarcane bagasse microfibrillated cellulose, and undergo vacuum-assisted liquid epoxy resin infusion to produce solid laminates after curing at ambient temperature. Quasi-static tensile, flexural and short beam testing at room temperature indicated that the stiffness, ultimate strength and toughness at ultimate load of the brand-new two-level hierarchical composite are substantially higher than in baseline, unsized fiber-reinforced epoxy laminate. Atomic force microscopy for height and phase imaging, along with scanning electron microscopy for the fracture surface survey, revealed a 400 nm-thick fiber/matrix interphase wherein microfibrillated cellulose exerts strengthening and toughening roles in the hybrid laminate. Market expansion of this class of continuous fiber-reinforced-polymer matrix composites exhibiting remarkable mechanical performance/cost ratios is thus conceivable.
Cylindrically symmetric, static strings with a cosmological constant in Brans-Dicke theory
Delice, Oezguer
2006-01-01
The static cylindrically symmetric vacuum solutions with a cosmological constant in the framework of the Brans-Dicke theory are investigated. Some of these solutions admitting Lorentz boost invariance along the symmetry axis correspond to local, straight cosmic strings with a cosmological constant. Some physical properties of such solutions are studied. These strings apply attractive or repulsive forces on the test particles. A smooth matching is also performed with a recently introduced interior thick string solution with a cosmological constant
Dexter, H. B.; Funk, J. G.
1986-01-01
Five through-the-thickness stitch configurations are analyzed to determine the effect of impact resistance and interlaminar fracture toughness on T3000/3501-6 graphite/epoxy. The test specimens were stitched with either polyester or Kevlar yarns and with various stitch parameters. Tension and compression mechanical, impact and compression-after-impact, and double cantilever beam tests were conducted. It is observed that the stitched laminates have tension and compression strengths 20-25 percent lower than the strengths of unstitched laminates, the tension strength of stitched laminates is reduced with increasing number of stitches, and the compression strength increases as the number of stitches are increased. The impact data reveal that the Kevlar stitched laminates have less damage than unstitched laminates; the most effective configuration for suppressing impact damage and improving interlaminar fracture toughness consists of Kevlar yarns 1/4 inch apart with eight stitches per inch. The mode 1 critical strain energy release rate for the 1/4 inch Kevlar eight stitch laminate was calculated as 30 times higher than that of the unstitched.
Fabrication and characterization of laminated Ti-(TiB+La2O3/Ti composite
Yuanfei Han
2015-10-01
Full Text Available The incorporation of ceramic particulate reinforcements into titanium alloys can improve the specific strength and specific stiffness, while inevitably reduce the plasticity and ductility. In this study, in situ synthesized multilayer Ti-(TiB+La2O3/Ti composite was designed by learning from the microstructure of nature biological materials with excellent mechanical properties. The Ti-(TiB+La2O3/Ti composite with unique characteristic of laminated structure was prepared by combined powder metallurgy and hot rolling. The method has the synthesize advantages with in-situ reaction of Ti and LaB6 at high temperature and controllability of reinforcements size and constituent phases in composites. The result shows that the pores in the as sintered laminated structure composite completely disappeared after hot rolling at 1050 °C. The agglomerated reinforcement particles were well dispersed and distributed uniformly along the rolling direction. The thickness of pure Ti layer and (TiB+La2O3/Ti composite layer decreased from 1 mm to about 200 μm. Meanwhile, the grains size was refined obviously after rolling deformation. The room temperature tensile test indicates that the elongation of the laminated Ti-(TiB+La2O3/Ti composite improved from 13% to 17% in comparison with the uniform (TiB+La2O3/Ti composite, while the tensile strength had little change. It provides theoretical and experimental basis for fabricating the novel high performance laminated Ti-(TiB+La2O3/Ti composites.
A thick level set interface model for simulating fatigue-drive delamination in composites
Latifi, M.; Van der Meer, F.P.; Sluys, L.J.
2015-01-01
This paper presents a new damage model for simulating fatigue-driven delamination in composite laminates. This model is developed based on the Thick Level Set approach (TLS) and provides a favorable link between damage mechanics and fracture mechanics through the non-local evaluation of the energy
Quasi-Static Indentation Analysis of Carbon-Fiber Laminates.
Briggs, Timothy [Sandia National Lab. (SNL-CA), Livermore, CA (United States); English, Shawn Allen [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Nelson, Stacy Michelle [Sandia National Lab. (SNL-CA), Livermore, CA (United States)
2015-12-01
A series of quasi - static indentation experiments are conducted on carbon fiber reinforced polymer laminates with a systematic variation of thicknesses and fixture boundary conditions. Different deformation mechanisms and their resulting damage mechanisms are activated b y changing the thickn ess and boundary conditions. The quasi - static indentation experiments have been shown to achieve damage mechanisms similar to impact and penetration, however without strain rate effects. The low rate allows for the detailed analysis on the load response. Moreover, interrupted tests allow for the incremental analysis of various damage mechanisms and pr ogressions. The experimentally tested specimens are non - destructively evaluated (NDE) with optical imaging, ultrasonics and computed tomography. The load displacement responses and the NDE are then utilized in numerical simulations for the purpose of model validation and vetting. The accompanying numerical simulation work serves two purposes. First, the results further reveal the time sequence of events and the meaning behind load dro ps not clear from NDE . Second, the simulations demonstrate insufficiencies in the code and can then direct future efforts for development.
Optimization of sensor introduction into laminated composite materials
Schaaf, Kristin; Nemat-Nasser, Sia
2008-03-01
This work seeks to extend the functionality of the composite material beyond that of simply load-bearing and to enable in situ sensing, without compromising the structural integrity of the host composite material. Essential to the application of smart composites is the issue of the mechanical coupling of the sensor to the host material. Here we present various methods of embedding sensors within the host composite material. In this study, quasi-static three-point bending (short beam) and fatigue three-point bending (short beam) tests are conducted in order to characterize the effects of introducing the sensors into the host composite material. The sensors that are examined include three types of polyvinylidene fluoride (PVDF) thin film sensors: silver ink with a protective coating of urethane, silver ink without a protective coating, and nickel-copper alloy without a protective coating. The methods of sensor integration include placement at the midplane between the layers of prepreg material as well as a sandwich configuration in which a PVDF thin film sensor is placed between the first and second and nineteenth and twentieth layers of prepreg. Each PVDF sensor is continuous and occupies the entire layer, lying in the plane normal to the thickness direction in laminated composites. The work described here is part of an ongoing effort to understand the structural effects of integrating microsensor networks into a host composite material.
An investigation on cylindrical imploding turbulent mixing
Liao Haidong; Yang Libin; Zhang Xilin; Ouyang Kai; Li Jun
2001-01-01
The interfacial instability experiments in cylindrically convergent geometry are performed by imploding jelly liner with high pressure gases; and instability growth were observed with high-speed framing camera. The relevant 2D numerical simulation programs were developed and their results are in good agreement with those of experiments
Wellposedness of a cylindrical shell model
McMillan, C.
1994-01-01
We consider a well-known model of a thin cylindrical shell with dissipative feedback controls on the boundary in the form of forces, shears, and moments. We show that the resulting closed loop feedback problem generates a s.c. semigroup of contractions in the energy space
Exact relativistic cylindrical solution of disordered radiation
Fonseca Teixeira, A.F. da; Wolk, I.; Som, M.M.
1976-05-01
A source free disordered distribution of electromagnetic radiation is considered in Einstein' theory, and a time independent exact solution with cylindrical symmetry is obtained. The gravitation and pressure effects of the radiation alone are sufficient to give the distribution an equilibrium. A finite maximum concentration is found on the axis of symmetry, and decreases monotonically to zero outwards. Timelike and null geodesics are discussed
Shear stresses around circular cylindrical openings
Hoogenboom, P.C.J.; Van Weelden, C.; Blom, C.M.B.
2010-01-01
In this paper stress concentrations are studied around circular cylindrical openings or voids in a linear elastic continuum. The loading is such that a uniform shear stress occurs in the continuum, which is disturbed by the opening. The shear stress is in the direction of the centre axis of the
On isotropic cylindrically symmetric stellar models
Nolan, Brien C; Nolan, Louise V
2004-01-01
We attempt to match the most general cylindrically symmetric vacuum spacetime with a Robertson-Walker interior. The matching conditions show that the interior must be dust filled and that the boundary must be comoving. Further, we show that the vacuum region must be polarized. Imposing the condition that there are no trapped cylinders on an initial time slice, we can apply a result of Thorne's and show that trapped cylinders never evolve. This results in a simplified line element which we prove to be incompatible with the dust interior. This result demonstrates the impossibility of the existence of an isotropic cylindrically symmetric star (or even a star which has a cylindrically symmetric portion). We investigate the problem from a different perspective by looking at the expansion scalars of invariant null geodesic congruences and, applying to the cylindrical case, the result that the product of the signs of the expansion scalars must be continuous across the boundary. The result may also be understood in relation to recent results about the impossibility of the static axially symmetric analogue of the Einstein-Straus model
A strong focussing cylindrical electrostatic quadrupole
Sheng Yaochang
1986-01-01
The construction and performance of small cylindrical electrostatic quadrupole, which is installed in JM-400 pulse electrostatic accelerator, are described. This electrostatic quadrupole is not only used in neutron generator, but also suitable for ion injector as well as for low energy electron accelerator
Cylindrical Induction Melter Modicon Control System
Weeks, G.E.
1998-04-01
In the last several years an extensive R ampersand D program has been underway to develop a vitrification system to stabilize Americium (Am) and Curium (Cm) inventories at SRS. This report documents the Modicon control system designed for the 3 inch Cylindrical Induction Melter (CIM)
A cylindrical furnace for absorption spectral studies
A cylindrical furnace with three heating zones, capable of providing a temperature of 1100°C, has been fabricated to enable recording of absorption spectra of high temperature species. The temperature of the furnace can be controlled to ± 1°C of the set temperature. The salient feature of this furnace is that the material ...
Laminitis subclínica en bovinos
Franco, M. S.; Oliver, O. J.
2012-01-01
La laminitis subclínica es una entidad multifactorial que afecta a los bovinos especialmente en el periodo del periparto. Se caracteriza por la coloración amarilla de la suela, hemorragias de la suela, separación de la línea blanca y erosiones de talón. Se considera que es el mayor factor predisponente para la presentación de cojeras de pezuña a causa del debilitamiento del tejido corneo de la misma, lo que comrpromete el bienestar del animal y acarrea perdidas económicas directas e indirecta...
Electroform/Plasma-Spray Laminates for X-Ray Optics
Ulmer, Melville P.; Graham, Michael; Vaynman, Semyon
2007-01-01
Electroform/plasma-spray laminates have shown promise as lightweight, strong, low-thermal-expansion components for xray optics. The basic idea is to exploit both (1) the well-established art of fabrication of optical components by replication and (2) plasma spraying as a means of reinforcing a thin replica optic with one or more backing layer(s) having tailorable thermomechanical properties. In x-ray optics as in other applications, replication reduces the time and cost of fabrication because grinding and polishing can be limited to a few thick masters, from which many lightweight replicas can thereafter be made. The first step in the fabrication of a component of the type in question is to make a replica optic by electroforming a thin layer of nickel on a master. Through proper control of the electroforming process conditions, it is possible to minimize residual stress and, hence, to minimize distortion in the replica. Next, a powder comprising ceramic particles coated with a metal compatible with the electroformed nickel is plasma-sprayed onto the backside of the nickel replica. Then through several repetitions and variations of the preceding steps or perhaps a small compressive stress, alternating layers of electroformed nickel and plasma-sprayed metal-coated ceramic powder are deposited. The thicknesses of the layers and the composition of the metal-coated ceramic powder are chosen to optimize the strength, areal mass density, and toughness of the finished component. An important benefit of using both electroforming and plasma spraying is the possibility of balancing stresses to a minimum level, which could be zero or perhaps a small net compressive stress designed to enhance the function of the component in its intended application.
Mechanical properties and the laminate structure of Arapaima gigas scales.
Lin, Y S; Wei, C T; Olevsky, E A; Meyers, Marc A
2011-10-01
The Arapaima gigas scales play an important role in protecting this large Amazon basin fish against predators such as the piranha. They have a laminate composite structure composed of an external mineralized layer and internal lamellae with thickness of 50-60 μm each and composed of collagen fibers with ~1 μm diameter. The alignment of collagen fibers is consistent in each individual layer but varies from layer to layer, forming a non-orthogonal plywood structure, known as Bouligand stacking. X-ray diffraction revealed that the external surface of the scale contains calcium-deficient hydroxyapatite. EDS results confirm that the percentage of calcium is higher in the external layer. The micro-indentation hardness of the external layer (550 MPa) is considerably higher than that of the internal layer (200 MPa), consistent with its higher degree of mineralization. Tensile testing of the scales carried out in the dry and wet conditions shows that the strength and stiffness are hydration dependent. As is the case of most biological materials, the elastic modulus of the scale is strain-rate dependent. The strain-rate dependence of the elastic modulus, as expressed by the Ramberg-Osgood equation, is equal to 0.26, approximately ten times higher than that of bone. This is attributed to the higher fraction of collagen in the scales and to the high degree of hydration (30% H(2)O). Deproteinization of the scale reveals the structure of the mineral component consisting of an interconnected network of platelets with a thickness of ~50 nm and diameter of ~500 nm. Copyright © 2011 Elsevier Ltd. All rights reserved.
Yuan, Li-Yun; Xiang, Yu; Lu, Jing; Jiang, Hong-Hua
2015-12-01
Based on the transfer matrix method of exploring the circular cylindrical shell treated with active constrained layer damping (i.e., ACLD), combined with the analytical solution of the Helmholtz equation for a point source, a multi-point multipole virtual source simulation method is for the first time proposed for solving the acoustic radiation problem of a submerged ACLD shell. This approach, wherein some virtual point sources are assumed to be evenly distributed on the axial line of the cylindrical shell, and the sound pressure could be written in the form of the sum of the wave functions series with the undetermined coefficients, is demonstrated to be accurate to achieve the radiation acoustic pressure of the pulsating and oscillating spheres respectively. Meanwhile, this approach is proved to be accurate to obtain the radiation acoustic pressure for a stiffened cylindrical shell. Then, the chosen number of the virtual distributed point sources and truncated number of the wave functions series are discussed to achieve the approximate radiation acoustic pressure of an ACLD cylindrical shell. Applying this method, different radiation acoustic pressures of a submerged ACLD cylindrical shell with different boundary conditions, different thickness values of viscoelastic and piezoelectric layer, different feedback gains for the piezoelectric layer and coverage of ACLD are discussed in detail. Results show that a thicker thickness and larger velocity gain for the piezoelectric layer and larger coverage of the ACLD layer can obtain a better damping effect for the whole structure in general. Whereas, laying a thicker viscoelastic layer is not always a better treatment to achieve a better acoustic characteristic. Project supported by the National Natural Science Foundation of China (Grant Nos. 11162001, 11502056, and 51105083), the Natural Science Foundation of Guangxi Zhuang Autonomous Region, China (Grant No. 2012GXNSFAA053207), the Doctor Foundation of Guangxi
Charge Distribution Dependency on Gap Thickness of CMS Endcap RPC
Park, Sung K.; Lee, Kyongsei
2016-01-01
We report a systematic study of charge distribution dependency of CMS Resistive Plate Chamber (RPC) on gap thickness. Prototypes of double-gap RPCs with six different gap thickness ranging from from 1.0 to 2.0 mm in 0.2-mm steps have been built with 2-mm-thick phenolic high-pressure-laminated plates. The efficiencies of the six gaps are measured as a function of the effective high voltages. We report that the strength of the electric fields of the gap is decreased as the gap thickness is increased. The distributions of charges in six gaps are measured. The space charge effect is seen in the charge distribution at the higher voltages. The logistic function is used to fit the charge distribution data. Smaller charges can be produced within smaller gas gap. But the digitization threshold should be also lowered to utilize these smaller charges.
Díaz, G A; Cruz, R A; Chávez, A M
2013-01-01
Bamboo is considered one of the best timber resources in the world because for its mechanical properties and high sustainability; this research aims to improve the mechanical properties of the laminated glued bamboo Guadua Angustifolia Kunth (GAK) for use as structural elements, starting from de very manufacture process; this is important because it is possible to observe variations in the flexural strength and the elastic modulus in GAK samples taken from different heights and thickness of the culm. In order to analyze the influence of these final mechanical properties variations in the laminated, the height of the culm where samples are extracted (cepa, basa and sobrebasa) it is taken as a variable from where different types of laminated were manufactured, seeking to make optimal the configuration based in the transversal section area and the material strength. Three assemblies were designed varying the overlap of the adhesion lines and it concluded that the highest strength average values were obtained in the laminated composites manufactured with samples taken from the bottom of the culm (basa), which is possible because in these elements there are less adhesion lines than the other ones (middle, top and mixed) or the better matching of themselves
Jegley, Dawn C.
1988-01-01
Natural vibration frequencies of orthotropic and anisotropic simply supported right circular cylinders are predicted using a higher-order transverse-shear deformation theory. A comparison of natural vibration frequencies predicted by first-order transverse-shear deformation theory and the higher-order theory shows that an additional allowance for transverse shear deformation has a negligible effect on the lowest predicted natural vibration frequencies of laminated cylinders but significantly reduces the higher natural vibration frequencies. A parametric study of the effects of ply orientation on the natural vibration frequencies of laminated cylinders indicates that while stacking sequence affects natural vibration frequencies, cylinder geometry is more important in predicting transverse-shear deformation effects. Interaction curves for cylinders subjected to axial compressive loadings and low natural vibration frequencies indicate that transverse shearing effects are less important in predicting low natural vibration frequencies than in predicting axial compressive buckling loads. The effects of anisotropy are more important than the effects of transverse shear deformation for most strongly anisotropic laminated cylinders in predicting natural vibration frequencies. However, transverse-shear deformation effects are important in predicting high natural vibration frequencies of thick-walled laminated cylinders. Neglecting either anisotropic effects or transverse-shear deformation effects leads to non-conservative errors in predicted natural vibration frequencies.
Jegley, Dawn C.
1989-01-01
Natural vibration frequencies of orthotropic and anisotropic simply supported right circular cylinders are predicted using a higher-order transverse-shear deformation theory. A comparison of natural vibration frequencies predicted by first-order transverse-shear deformation theory and the higher-order theory shows that an additional allowance for transverse shear deformation has a negligible effect on the lowest predicted natural vibration frequencies of laminated cylinders but significantly reduces the higher natural vibration frequencies. A parametric study of the effects of ply orientation on the natural vibration frequencies of laminated cylinders indicates that while stacking sequence affects natural vibration frequencies, cylinder geometry is more important in predicting transverse-shear deformation effects. Interaction curves for cylinders subjected to axial compressive loadings and low natural vibration frequencies indicate that transverse shearing effects are less important in predicting low natural vibration frequencies than in predicting axial compressive buckling loads. The effects of anisotropy are more important than the effects of transverse shear deformation for most strongly anisotropic laminated cylinders in predicting natural vibration frequencies. However, transverse-shear deformation effects are important in predicting high natural vibration frequencies of thick-walled laminated cylinders. Neglecting either anisotropic effects or transverse-shear deformation effects leads to non-conservative errors in predicted natural vibration frequencies.
Du, Y.; Fan, G.H.; Yu, Tianbo
2015-01-01
A laminated Ti-Al composite has been fabricated by hot compaction and hot rolling of alternate layers of commercial purity Ti and Al sheets with a thickness of 200 μm. The hot compaction temperature was 500˚C and in a following step the composite has been reduced 50% in thickness by hot rolling....... The fully consolidated composite has been annealed at 300˚C and 500˚C for different length of time. As a result of the differences in crystal structure and mechanical properties between Ti and Al protrusions and retrusions formed at the interface. A heterogeneous interface has thereby been created...
Hole-thru-laminate mounting supports for photovoltaic modules
Wexler, Jason; Botkin, Jonathan; Culligan, Matthew; Detrick, Adam
2015-02-17
A mounting support for a photovoltaic module is described. The mounting support includes a pedestal having a surface adaptable to receive a flat side of a photovoltaic module laminate. A hole is disposed in the pedestal, the hole adaptable to receive a bolt or a pin used to couple the pedestal to the flat side of the photovoltaic module laminate.
78 FR 23591 - Certain Prepregs, Laminates, and Finished Circuit Boards
2013-04-19
... INTERNATIONAL TRADE COMMISSION [Investigation No. 337-TA-659 (Enforcement)] Certain Prepregs... United States after importation of certain prepregs, laminates, and finished circuit boards that infringe... prepregs and laminates that are the subject of the investigation or that otherwise infringe, induce, and/or...
Lateral testing of glued laminated timber tudor arch
Douglas R. Rammer; Philip Line
2016-01-01
Glued laminated timber Tudor arches have been in wide use in the United States since the 1930s, but detailed knowledge related to seismic design in modern U.S. building codes is lacking. FEMA P-695 (P-695) is a methodology to determine seismic performance factors for a seismic force resisting system. A limited P-695 study for glued laminated timber arch structures...
Bayesian inference model for fatigue life of laminated composites
Dimitrov, Nikolay Krasimirov; Kiureghian, Armen Der; Berggreen, Christian
2016-01-01
A probabilistic model for estimating the fatigue life of laminated composite plates is developed. The model is based on lamina-level input data, making it possible to predict fatigue properties for a wide range of laminate configurations. Model parameters are estimated by Bayesian inference. The ...
Nuclear lamins: laminopathies and their role in premature ageing
Broers, J.L.V.; Ramaekers, F.C.S.; Bonne, G.; Yaou, R.; Hutchison, C.J.
2006-01-01
It has been demonstrated that nuclear lamins are important proteins in maintaining cellular as well as nuclear integrity, and in maintaining chromatin organization in the nucleus. Moreover, there is growing evidence that lamins play a prominent role in transcriptional control. The family of
Laminated lumber may be more profitable than sawn lumber
P. Koch
1976-01-01
By laminating 1/4-in. rotary-cut veneer into structural lumber, manufacturers can expand lumber output by at least 30% without increasing volume logged. The idea merits intensive study. Manufacturing plus raw material costs should total about $142/Mbf; sales price for desirable widths and lengths of the strong laminated product should approach or exceed $200/Mbf.
Fatigue Performance of Composite Laminates After Low-velocity Impact
LIANG Xiao-lin
2016-12-01
Full Text Available Compression-compression fatigue tests were carried out on T300/5405 composite laminates after low-velocity impact, compression performance of the laminates with different impact damages was studied together with its fatigue life and damage propagation under different stress levels, then the effects of impact energy, stress level and damage propagation on fatigue life of laminates were discussed. The results indicate that impact damage can greatly reduce the residual strength of laminates; under low fatigue load levels, the higher impact energy is, the shorter the fatigue life of laminates with impact damage will be; damage propagation undergoes two stages during the fatigue test, namely the steady propagation and the rapid propagation, accounting for 80% and 20% of the overall fatigue life, respectively; damage propagation rate decreases with the reduction of stress level.
Water entry of cylindrical bodies with various aspect ratios
Kim, Nayoung; Park, Hyungmin
2017-11-01
We experimentally investigate the water entry of cylindrical bodies with different aspect ratio (1.0-8.0), focusing on the deformation of free surface and resulting phenomena over and under the surface. The experiment is performed using a high-speed imaging (upto 10000 fps) and PIV. The head and tail of bodies are hemispherical and the nose part is additionally roughened with a sandpaper to see the effect of roughness as well. The release height is also adjusted to change the impact velocity at the free surface (Reynolds number is order of 105). For smooth surface (without cavity formation), a thin liquid film rises up the body after impacting, gathers at the pole and forms a jet over the free surfaces. The jet is created in the form of a thick and thin jet. The thin jet is produced by a water film riding up the surface of an object, and a thick jet is produced by rising water from underwater as the object sinks. However, as the aspect ratio increases, the liquid film does not fully ride up the body and cannot close, so there is an empty space below the free surface. With roughness (with cavity), the liquid film is detached from the body and splash/dome is formed above the free surface. The splash height and its collapsing time decrease with increasing the aspect ratio. Supported by Grants (MPSS-CG-2016-02, NRF-2017R1A4A1015523) of the Korea government.
High Pressure Laminates with Antimicrobial Properties
Sandra Magina
2016-02-01
Full Text Available High-pressure laminates (HPLs are durable, resistant to environmental effects and good cost-benefit decorative surface composite materials with special properties tailored to meet market demand. In the present work, polyhexamethylene biguanide (PHMB was incorporated for the first time into melamine-formaldehyde resin (MF matrix on the outer layer of HPLs to provide them antimicrobial properties. Chemical binding of PHMB to resin matrix was detected on the surface of produced HPLs by attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR. Antimicrobial evaluation tests were carried out on the ensuing HPLs doped with PHMB against gram-positive Listeria innocua and gram-negative Escherichia coli bacteria. The results revealed that laminates prepared with 1.0 wt % PHMB in MF resin were bacteriostatic (i.e., inhibited the growth of microorganisms, whereas those prepared with 2.4 wt % PHMB in MF resin exhibited bactericidal activity (i.e., inactivated the inoculated microorganisms. The results herein reported disclose a promising strategy for the production of HPLs with antimicrobial activity without affecting basic intrinsic quality parameters of composite material.
Numerical Investigation of Corrugated Wire Mesh Laminate
Jeongho Choi
2013-01-01
Full Text Available The aim of this work is to develop a numerical model of Corrugated Wire Mesh Laminate (CWML capturing all its complexities such as nonlinear material properties, nonlinear geometry and large deformation behaviour, and frictional behaviour. Development of such a model will facilitate numerical simulation of the mechanical behaviour of the wire mesh structure under various types of loading as well as the variation of the CWML configuration parameters to tailor its mechanical properties to suit the intended application. Starting with a single strand truss model consisting of four waves with a bilinear stress-strain model to represent the plastic behaviour of stainless steel, the finite element model is gradually built up to study single-layer structures with 18 strands of corrugated wire meshes consistency and double- and quadruple-layered laminates with alternating crossply orientations. The compressive behaviour of the CWML model is simulated using contact elements to model friction and is compared to the load-deflection behaviour determined experimentally in uniaxial compression tests. The numerical model of the CWML is then employed to conduct the aim of establishing the upper and lower bounds of stiffness and load capacity achievable by such structures.
Acoustic resonance scattering from a multilayered cylindrical shell with imperfect bonding.
Rajabi, M; Hasheminejad, Seyyed M
2009-12-01
The method of wave function expansion is adopted to study the three dimensional scattering of a time-harmonic plane progressive sound field obliquely incident upon a multi-layered hollow cylinder with interlaminar bonding imperfection. For the generality of solution, each layer is assumed to be cylindrically orthotropic. An approximate laminate model in the context of the modal state equations with variable coefficients along with the classical T-matrix solution technique is set up for each layer to solve for the unknown modal scattering and transmission coefficients. A linear spring model is used to describe the interlaminar adhesive bonding whose effects are incorporated into the global transfer matrix by introduction of proper interfacial transfer matrices. Following the classic acoustic resonance scattering theory (RST), the scattered field and response to surface waves are determined by constructing the partial waves and obtaining the non-resonance (backgrounds) and resonance components. The solution is first used to investigate the effect of interlayer imperfection of an air-filled and water submerged bilaminate aluminium cylindrical shell on the resonances associated with various modes of wave propagation (i.e., symmetric/asymmetric Lamb waves, fluid-borne A-type waves, Rayleigh and Whispering Gallery waves) appearing in the backscattered spectrum, according to their polarization and state of stress. An illustrative numerical example is also given for a multi-layered (five-layered) cylindrical shell for which the stiffness of the adhesive interlayers is artificially varied. The sensitivity of resonance frequencies associated with higher mode numbers to the stiffness coefficients is demonstrated to be a good measure of the bonding strength. Limiting cases are considered and fair agreements with solutions available in the literature are established.
Silami, Francisca Daniele Jardilino; Tonani, Rafaella; Alandia-Román, Carla Cecilia; Pires-de-Souza, Fernanda de Carvalho Panzeri
2016-01-01
The aim of this study was to evaluate the influence of accelerated aging (AAA) on the color stability of resin cements for bonding ceramic laminate veneers of different thicknesses. The occlusal surfaces of 80 healthy human molars were flattened. Ceramic laminate veneers (IPS e-max Ceram) of two thicknesses (0.5 and 1.0 mm) were bonded with three types of luting agents: light-cured, conventional dual and self-adhesive dual cement. Teeth without restorations and cement samples (0.5 mm) were used as control. After initial color evaluations, the samples were subjected to AAA for 580 h. After this, new color readouts were made, and the color stability (ΔE) and luminosity (ΔL) data were analyzed. The greatest color changes (p<0.05) occurred when 0.5 mm veneers were fixed with light-cured cement and the lowest when 1.0 mm veneers were fixed with conventional dual cement. There was no influence of the restoration thickness when the self-adhesive dual cement was used. When veneers were compared with the control groups, it was verified that the cement samples presented the greatest alterations (p<0.05) in comparison with both substrates and restored teeth. Therefore, it was concluded that the thickness of the restoration influences color and luminosity changes for conventional dual and light-cured cements. The changes in self-adhesive cement do not depend on restoration thickness.
Robotic Hand with Flexible Fingers for Grasping Cylindrical Objects
柴田, 瑞穂
2015-01-01
In this manuscript, a robotic hand for grasping a cylindrical object is proposed. This robotic hand has flexible fingers that can hold a cylindrical object during moving. We introduce a grasping strategy for a cylindrical object in terms of state transition graph. In this strategy the robotic hand picks up the cylindrical object utilizing a suction device before the hand grasp the object. We also design the flexible fingers; then, we investigate the validity of this robotic hand via several e...
Park, Chang Gyu; Kim, Tae Sung; Kim, Hoe Woong; Kim, Jong Bum
2013-01-01
A coolant free surface level is dependent on the operating conditions, and thus the fluid added mass caused by contacting sodium with the structure affects the dynamic characteristic of the UIS. In this study, a numerical analysis model was proposed and a feasibility study was performed through structural testing. The dynamic characteristics for a simple cylindrical structure simulating the UIS outer cylinder will be tested. Currently, the FE analyses were carried out to confirm the effect of water chamber structure on the natural frequency of the test model. The submerged condition of a UIS cylinder affects its natural frequency. A test model of a simple cylindrical structure was prepared to conduct a dynamic test, and each structure component of the test equipment may affect the natural frequency. A cup-shaped cylindrical structure was applied to develop the numerical analysis method for a structure submerged in water and it was verified through a structural test. With this numerical analysis model, the effect of the water chamber material for a simple cylindrical structure was studied. The candidate materials for water chamber were acryl and 316SS with different thicknesses. Both materials showed a higher natural frequency than the reference model. A water chamber made of 316SS with a thick wall gave a closer result to the reference natural frequency than an acryl chamber. The expected natural frequency of the test facility has about a 4% difference based on the reference value, considering a water chamber with a 1 cm thickness. This result will be verified through an ongoing future structural test activity
Cylindrical continuous martingales and stochastic integration in infinite dimensions
Veraar, M.C.; Yaroslavtsev, I.S.
2016-01-01
In this paper we define a new type of quadratic variation for cylindrical continuous local martingales on an infinite dimensional spaces. It is shown that a large class of cylindrical continuous local martingales has such a quadratic variation. For this new class of cylindrical continuous local
Analysis of Usability in Furniture Production of Wood Plastic Laminated Board
Abdullah Cemil Ilçe
2015-05-01
Full Text Available The objective of this study was to manufacture a lightweight and easily producible wood plastic laminate (WPL board that could be used in the furniture sector. Eastern beech (Fagus orientalis L. veneer papels (A and hollow polycarbonate boards (B, both with a thickness of 4 mm, were laminated in different combinations using polyurethane (PUR and polychloroprene (PCR adhesives. The physical and mechanical properties of the WPL boards obtained were determined according to the principles specified in the EN 326-1, EN 317, EN 310, ASTM D1037, and ASTM D1761 standards. Subsequently, the specimens were compared with particle boards (PB, medium density fiberboards (MDF, and okoume plywoods (PW. According to the results, the AABAA, ABABA, and ABBBA combinations of the WPL materials had better physical properties, such as weight, water absorption, and swelling thickness, compared to the other composites. Furthermore, because the WPL materials had a high bending resistance, modulus of elasticity, and nail and screw withdrawal strength, they could be used instead of PB and MDF. The WPL material obtained within the scope of this study are suitable for furniture making.
Development of a Higher Order Laminate Theory for Modeling Composites with Induced Strain Actuators
Chattopadhyay, Aditi; Seeley, Charles E.
1996-01-01
A refined higher order plate theory is developed to investigate the actuation mechanism of piezoelectric materials surface bonded or embedded in composite laminates. The current analysis uses a displacement field which accurately accounts for transverse shear stresses. Some higher order terms are identified by using the conditions that shear stresses vanish at all free surfaces. Therefore, all boundary conditions for displacements and stresses are satisfied in the present theory. The analysis is implemented using the finite element method which provides a convenient means to construct a numerical solution due to the discrete nature of the actuators. The higher order theory is computationally less expensive than a full three dimensional analysis. The theory is also shown to agree well with published experimental results. Numerical examples are presented for composite plates with thicknesses ranging from thin to very thick.
Investigation on Surface Roughness in Cylindrical Grinding
Rudrapati, Ramesh; Bandyopadhyay, Asish; Pal, Pradip Kumar
2011-01-01
Cylindrical grinding is a complex machining process. And surface roughness is often a key factor in any machining process while considering the machine tool or machining performance. Further, surface roughness is one of the measures of the technological quality of the product and is a factor that greatly influences cost and quality. The present work is related to some aspects of surface finish in the context of traverse-cut cylindrical grinding. The parameters considered have been: infeed, longitudinal feed and work speed. Taguchi quality design is used to design the experiments and to identify the significantly import parameter(s) affecting the surface roughness. By utilization of Response Surface Methodology (RSM), second order differential equation has been developed and attempts have also been made for optimization of the process in the context of surface roughness by using C- programming.
Method of dismantling cylindrical structure by cutting
Harada, Minoru; Mitsuo, Kohei; Yokota, Isoya; Nakamura, Kenjiro.
1989-01-01
This invention concerns a method of cutting and removing cylindrical structures, for example, iron-reinforced concrete materials such as thermal shielding walls in BWR type power plants into block-like form. That is, in a method of cutting and removing the cylindrical structure from the side of the outer wall, the structural material is cut from above to below successively in the axial direction and the circumferential direction by means abrasive jet by remote operation and cut into blocks each of a predetermined size. The cut out blocks are successively taken out. Cutting of the material from above to below by remote operation and taking out of small blocks causes no hazards to human body. Upon practicing the present invention, it is preferred to use a processing device for slurry and exhaust gases for preventing scattering of activated dismantled pieces or powdery dusts. (K.M.)
Cylindrically converging blast waves in air
Matsuo, H.; Nakamura, Y.
1981-07-01
Cylindrically converging shock waves are produced by utilizing the detonation of cylindrical explosive shells. The production and the propagation of shock waves are observed by framing and streak camera photographs, and the trajectory of shock propagations is determined by using an electrical ionization probing system. The effect of the quantity of explosives on the stability, or the axial symmetry, of shock fronts and on the strength of shocks produced is investigated. It has been shown that, for practical purposes, the approximation of shock trajectories by Guderley's formulas would be sufficiently acceptable in an unexpectedly wide region near the implosion center, and that the axial symmetry of the shock front is improved by increasing the quantity of explosives, and thus, strong shocks are produced by merely increasing the quantity of explosives. The reflected diverging shock seems to be very stable. Piezoelectric elements have also been used to detect reflected diverging waves.
Rohem, N.R.F.; Sampaio, E.M.; Queiroz, R.A.; Cortines, V.J. [Universidade do Estado do Rio de Janeiro (LAA/UERJ), Campus Regional - Instituto Politecnico (IPRJ) - Laboratorio de Adesao e Aderencia, Nova Friburgo, RJ (Brazil)], e-mail: nrohem@iprj.uerj.br
2010-07-01
The use of polymeric matrix composites to repair and strengthen structures in the oil industry has become a common industry practice. In the year of 2006 the ISO/PDTS 24817 'Petroleum, petrochemical and natural gas industries - Qualification, design, installation, testing and inspection' was presented. This study presents the development of a new laminate, manual lamination process, and some of the certifying tests in accordance with ISO, for through-wall damage repairs. The test consists of applying the composite laminate repair in 9 carbon steel tubes, NPS6, with 600mm of length, with drilled holes of 10, 15, and 25mm. After the curing time a hydrostatic test is performed. The laminate must fail by delamination at the substrate/composite interface. With this test we obtain the {lambda}LCL (energy release rate), used to determine the thickness of the repair applied in tubes with through-wall damage. (author)
Escape and transmission probabilities in cylindrical geometry
Bjerke, M.A.
1980-01-01
An improved technique for the generation of escape and transmission probabilities in cylindrical geometry was applied to the existing resonance cross section processing code ROLAIDS. The algorithm of Hwang and Toppel, [ANL-FRA-TM-118] (with modifications) was employed. The probabilities generated were found to be as accurate as those given by the method previously applied in ROLAIDS, while requiring much less computer core storage and CPU time
The large cylindrical drift chamber of TASSO
Boerner, H.; Fischer, H.M.; Hartmann, H.; Loehr, B.; Wollstadt, M.; Fohrmann, R.; Schmueser, P.; Cassel, D.G.; Koetz, U.; Kowalski, H.
1980-03-01
We have built and operated a large cylindrical drift chamber for the TASSO experiment at the DESY storage ring, PETRA. The chamber has a length of 3.5 m, a diameter of 2.5 m, and a total of 2340 drift cells. The cells are arranged in 15 concentric layers such that tracks can be reconstructed in three dimensions. A spatial resolution of 220 μm has been achieved for tracks of normal incidence on the drift cells. (orig.)
Magnetic guns with cylindrical permanent magnets
Vokoun, David; Beleggia, M.; Heller, Luděk
2012-01-01
Roč. 324, č. 9 (2012), s. 1715-1719 ISSN 0304-8853 R&D Projects: GA ČR(CZ) GAP107/11/0391; GA AV ČR IAA100100920 Institutional research plan: CEZ:AV0Z10100520 Keywords : permanent magnet * cylindrical magnet * Earnshaw's theorem * magnetic gun * magnetostatic interaction Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.826, year: 2012 http://www.sciencedirect.com/science/article/pii/S0304885311008997
Transmission of infrared radiation through cylindrical waveguides
Nucara, A.; Dore, P.; Calvani, P.; Cannavo', D.; Marcelli, A.
1998-01-01
Measurement of the transmittance of infrared radiation (v -1 ) through cylindrical waveguides are presented and discussed. The experimental results are compared with numerical simulations, obtained through conventional ray tracing programs. Finally, it' estimated the transmittance of a waveguide in the case of an infrared synchrotron radiation source. Are applied the results to the case of the DAΦNE collider, where a synchrotron radiation beamline for the far infrared is under construction
A 2D analytical cylindrical gate tunnel FET (CG-TFET) model: impact of shortest tunneling distance
Dash, S.; Mishra, G. P.
2015-09-01
A 2D analytical tunnel field-effect transistor (FET) potential model with cylindrical gate (CG-TFET) based on the solution of Laplace’s equation is proposed. The band-to-band tunneling (BTBT) current is derived by the help of lateral electric field and the shortest tunneling distance. However, the analysis is extended to obtain the subthreshold swing (SS) and transfer characteristics of the device. The dependency of drain current, SS and transconductance on gate voltage and shortest tunneling distance is discussed. Also, the effect of scaling the gate oxide thickness and the cylindrical body diameter on the electrical parameters of the device is analyzed.
A 2D analytical cylindrical gate tunnel FET (CG-TFET) model: impact of shortest tunneling distance
Dash, S; Mishra, G P
2015-01-01
A 2D analytical tunnel field-effect transistor (FET) potential model with cylindrical gate (CG-TFET) based on the solution of Laplace’s equation is proposed. The band-to-band tunneling (BTBT) current is derived by the help of lateral electric field and the shortest tunneling distance. However, the analysis is extended to obtain the subthreshold swing (SS) and transfer characteristics of the device. The dependency of drain current, SS and transconductance on gate voltage and shortest tunneling distance is discussed. Also, the effect of scaling the gate oxide thickness and the cylindrical body diameter on the electrical parameters of the device is analyzed. (paper)
Cylindric-like algebras and algebraic logic
Ferenczi, Miklós; Németi, István
2013-01-01
Algebraic logic is a subject in the interface between logic, algebra and geometry, it has strong connections with category theory and combinatorics. Tarski’s quest for finding structure in logic leads to cylindric-like algebras as studied in this book, they are among the main players in Tarskian algebraic logic. Cylindric algebra theory can be viewed in many ways: as an algebraic form of definability theory, as a study of higher-dimensional relations, as an enrichment of Boolean Algebra theory, or, as logic in geometric form (“cylindric” in the name refers to geometric aspects). Cylindric-like algebras have a wide range of applications, in, e.g., natural language theory, data-base theory, stochastics, and even in relativity theory. The present volume, consisting of 18 survey papers, intends to give an overview of the main achievements and new research directions in the past 30 years, since the publication of the Henkin-Monk-Tarski monographs. It is dedicated to the memory of Leon Henkin.
The analytic nodal method in cylindrical geometry
Prinsloo, Rian H.; Tomasevic, Djordje I.
2008-01-01
Nodal diffusion methods have been used extensively in nuclear reactor calculations, specifically for their performance advantage, but also for their superior accuracy. More specifically, the Analytic Nodal Method (ANM), utilising the transverse integration principle, has been applied to numerous reactor problems with much success. In this work, a nodal diffusion method is developed for cylindrical geometry. Application of this method to three-dimensional (3D) cylindrical geometry has never been satisfactorily addressed and we propose a solution which entails the use of conformal mapping. A set of 1D-equations with an adjusted, geometrically dependent, inhomogeneous source, is obtained. This work describes the development of the method and associated test code, as well as its application to realistic reactor problems. Numerical results are given for the PBMR-400 MW benchmark problem, as well as for a 'cylindrisized' version of the well-known 3D LWR IAEA benchmark. Results highlight the improved accuracy and performance over finite-difference core solutions and investigate the applicability of nodal methods to 3D PBMR type problems. Results indicate that cylindrical nodal methods definitely have a place within PBMR applications, yielding performance advantage factors of 10 and 20 for 2D and 3D calculations, respectively, and advantage factors of the order of 1000 in the case of the LWR problem
Combined tension and bending testing of tapered composite laminates
O'Brien, T. Kevin; Murri, Gretchen B.; Hagemeier, Rick; Rogers, Charles
1994-11-01
A simple beam element used at Bell Helicopter was incorporated in the Computational Mechanics Testbed (COMET) finite element code at the Langley Research Center (LaRC) to analyze the responce of tappered laminates typical of flexbeams in composite rotor hubs. This beam element incorporated the influence of membrane loads on the flexural response of the tapered laminate configurations modeled and tested in a combined axial tension and bending (ATB) hydraulic load frame designed and built at LaRC. The moments generated from the finite element model were used in a tapered laminated plate theory analysis to estimate axial stresses on the surface of the tapered laminates due to combined bending and tension loads. Surfaces strains were calculated and compared to surface strains measured using strain gages mounted along the laminate length. The strain distributions correlated reasonably well with the analysis. The analysis was then used to examine the surface strain distribution in a non-linear tapered laminate where a similarly good correlation was obtained. Results indicate that simple finite element beam models may be used to identify tapered laminate configurations best suited for simulating the response of a composite flexbeam in a full scale rotor hub.
Effect of nanomodified polyester resin on hybrid sandwich laminates
Anbusagar, NRR.; Giridharan, P.K.; Palanikumar, K.
2014-01-01
Highlights: • Effect of nanomodified polyester resin on hybrid sandwich laminates is evaluated. • The hybrid sandwich laminates are fabricated with varying wt% of nanoclay. • Flexural, impact and moisture absorbtion properties are evaluated for hybrid composites. • Scanning electron microscopy is utilized to analyze the dispersion of clay and fractured surfaces of the nanocomposites. - Abstract: Effect of nanoclay modified polyester resin on flexural, impact, hardness and water absorption properties of untreated woven jute and glass fabric hybrid sandwich laminates have been investigated experimentally. The hybrid sandwich laminates are prepared by hand lay-up manufacturing technique (HL) for investigation. All hybrid sandwich laminates are fabricated with a total of 10 layers, by varying the extreme layers and wt% of nanoclay in polyester resin so as to obtain four different combinations of hybrid sandwich laminates. For comparison of the composite with hybrid composite, jute fiber reinforced composite laminate also fabricated. X-ray diffraction (XRD) results obtained from samples with nanoclay indicated that intergallery spacing of the layered clay increases with matrix. Scanning electron microscopy (SEM) gave a morphological picture of the cross-sections and energy dispersive X-ray spectroscopy (EDS) allowed investigating the elemental composition of matrix in composites. The testing results indicated that the flexural properties are greatly increased at 4% of nanoclay loading while impact, hardness and water absorption properties are increased at 6% of nanoclay loading. A plausible explanation for high increase of properties has also been discussed
An, Jae-Yoon; Kim, Sumin; Kim, Hyun-Joong
2011-03-15
Formaldehyde was measured with a desiccator, a 20 L chamber and the FLEC method. The formaldehyde emission rate from laminate was the highest at 32 °C using the desiccator, which then decreased with time. The formaldehyde emission using the 20 L small chamber and FLEC showed a similar tendency. There was a strong correlation between the formaldehyde and total volatile organic compounds (TVOCs) with both types of floorings using the two different methods. The formaldehyde emission rate and TVOC results were higher when tested using the FLEC method than with the 20 L small chamber method. The emission rate was affected by the joint edge length in laminate flooring. Toluene, ethylbenzene and xylene were the main VOCs emitted from laminate flooring, and there were more unidentified VOCs emitted than identified VOCs. The samples heated with a floor heating system emitted more formaldehyde than those heated using an air circulation system due to the temperature difference between the bottom panel and flooring. The TVOC emission level of the samples was higher when an air circulation system was used than when a floor heating system was used due to the high ventilation rate. Copyright © 2010 Elsevier B.V. All rights reserved.
LamLum : a tool for evaluating the financial feasibility of laminated lumber plants
E.M. (Ted) Bilek; John F. Hunt
2006-01-01
A spreadsheet-based computer program called LamLum was created to analyze the economics of value- added laminated lumber manufacturing facilities. Such facilities manufacture laminations, typically from lower grades of structural lumber, then glue these laminations together to make various types of higher value laminated lumber products. This report provides the...
Aesthetic Qualities of Cross Laminated Timber
Bejder, Anne Kirkegaard
to its sustainable profile. In parallel to this, new production methods and further refined timber products have been developed. Among these are the engineered timber-based product Cross Laminated Timber (CLT) that show enhanced structural properties compared to unrefined timber. However, the question...... an undefined aesthetic potential that may innovate how we construct and perceive timber architecture, the overall aim of the thesis is to inquire into the architectural and aesthetic qualities of CLT. Through three chapters this thesis examines and discusses 1) the architectural qualities of CLT, 2......) the materiality of CLT, and 3) how one can deal with these qualitative aspects in the design process. This leads to: firstly, the development of an explicit model to help structuring the analysis and evaluation of the materiality of CLT, and secondly, a clarification and articulation of the aesthetic qualities...
Permeability After Impact Testing of Composite Laminates
Nettles, Alan T.
2003-01-01
Since composite laminates are beginning to be identified for use in reusable launch vehicle propulsion systems, an understanding of their permeance is needed. A foreign object impact event can cause a localized area of permeability (leakage) in a polymer matrix composite and it is the aim of this study to assess a method of quantifying permeability-after-impact results. A simple test apparatus is presented and variables that could affect the measured values of permeability-after-impact were assessed. Once it was determined that valid numbers were being measured, a fiber/resin system was impacted at various impact levels and the resulting permeability measured, first with a leak check solution (qualitative) then using the new apparatus (quantitative). The results showed that as the impact level increased, so did the measured leakage. As the pressure to the specimen was increased, the leak rate was seen to increase in a non-linear fashion for almost all of the specimens tested.
Yong Cao
2017-01-01
Full Text Available Determination of the local interlaminar stress distribution in a laminate with a bolt-filled hole is helpful for optimal bolted joint design, due to the three-dimensional (3D nature of the stress field near the bolt hole. A new interlaminar stress distribution phenomenon induced by the bolt-head and clamp-up load, which occurs in a filled-hole composite laminate, is investigated. In order to efficiently evaluate interlaminar stresses under the complex boundary condition, a calculation strategy that using zero-thickness cohesive interface element is presented and validated. The interface element is based on a linear elastic traction-separation description. It is found that the interlaminar stress concentrations occur at the hole edge, as well as the interior of the laminate near the periphery of the bolt head. In addition, the interlaminar stresses near the periphery of the bolt head increased with an increase in the clamp-up load, and the interlaminar normal and shear stresses are not at the same circular position. Therefore, the clamp-up load cannot improve the interlaminar stress distribution in the laminate near the periphery of the bolt head, although it can reduce the magnitude of the interlaminar shear stress at the hole edge. Thus, the interlaminar stress distribution phenomena may lead to delamination initiation in the laminate near the periphery of the bolt head, and should be considered in composite bolted joint design.
Motoki, S.; Fukuda, T. (Osaka City Univ., Osaka (Japan). Faculty of Engineering); Tanaka, M. (Kobe City College of Technology, Kobe (Japan))
1992-05-15
In this research, with regard to GFRP cross-ply laminates, which were the most basic lamination composition, the factors governing the progress of matrix cracks at the 90{degree} layer were studied, in particular the criterion for not depending on the thickness of the 90{degree} layer was examined. For the experiment concerning the above, GFRP prepreg was laminated and three kinds of cross-ply laminates were made for use. A quasistatic tensile load was applied to these specimens and a load-displacement curve was measured, and at the same time, the matrix crack numbers generated in the 90{degree} layer were counted. As a result, it was found that the maximum value of the vertical stress in the loading direction of 90{degree} layer did not depend on the lamination composition, hence could become the criterion for the crack progress. Also it was found that in case when this stress surpassed a certain threshold value, cracks were formed, but in case when it was smaller than the threshold value, no crack was formed. 12 refs., 14 figs.
Sørensen, Søren N.; Stolpe, Mathias
2015-01-01
rate. The capabilities of the method and the effect of active versus inactive manufacturing constraints are demonstrated on several numerical examples of limited size, involving at most 320 binary variables. Most examples are solved to guaranteed global optimality and may constitute benchmark examples...... but is, however, convex in the original mixed binary nested form. Convexity is the foremost important property of optimization problems, and the proposed method can guarantee the global or near-global optimal solution; unlike most topology optimization methods. The material selection is limited...... for popular topology optimization methods and heuristics based on solving sequences of non-convex problems. The results will among others demonstrate that the difficulty of the posed problem is highly dependent upon the composition of the constitutive properties of the material candidates....
Ionizing radiation thickness meters for materials in the form of sheets, coatings or laminates
1979-04-01
The draft standard deals with definitions and test methods for all measuring instruments used in connection with ionizing radiation, either for continuous operation or for discontinuous control measurements of plane materials or coating. It applies to systems where the signal relates directly to the measured value as well as to systems where the signal refers to the deviation from a given rated value. (orig./RW) [de
Modeling delamination of FRP laminates under low velocity impact
Jiang, Z.; Wen, H. M.; Ren, S. L.
2017-09-01
Fiber reinforced plastic laminates (FRP) have been increasingly used in various engineering such as aeronautics, astronautics, transportation, naval architecture and their impact response and failure are a major concern in academic community. A new numerical model is suggested for fiber reinforced plastic composites. The model considers that FRP laminates has been constituted by unidirectional laminated plates with adhesive layers. A modified adhesive layer damage model that considering strain rate effects is incorporated into the ABAQUS / EXPLICIT finite element program by the user-defined material subroutine VUMAT. It transpires that the present model predicted delamination is in good agreement with the experimental results for low velocity impact.
Olney, K L; Chiu, P H; Nesterenko, V F; Higgins, A; Serge, M; Weihs, T P; Fritz, G; Stover, A; Benson, D J
2014-01-01
Ni-Al laminates have shown promise as reactive materials due to their high energy release through intermetallic reaction. In addition to the traditional ignition methods, the reaction may be initiated in hot spots that can be created during mechanical loading. The explosively driven thick walled cylinder (TWC) technique was performed on two Ni-Al laminates composed of thin foil layers with different mesostructues: concentric and corrugated. These experiments were conducted to examine how these materials accommodate large plastic strain under high strain rates. Finite element simulations of these specimens with mesostuctures digitized from the experimental samples were conducted to provide insight into the mesoscale mechanisms of plastic flow. The dependence of dynamic behaviour on mesostructure may be used to tailor the hot spot formation and therefore the reactivity of the material system.
Sternstein, S. S.; Yang, P.
1983-01-01
A new test geometry, referred to as centro-symmetric deformation (CSD), is proposed for characterizing the viscoelastic behavior of the matrix of carbon-epoxy laminates. The sample consists of a thin disk, typically 6-14 plies thick, having a nominal diameter of 30 mm. The disk is freely supported on a circular anvil; the load is applied to the center of the disk using an 8-mm-diameter ball bearing nosepiece. The CSD test geometry provides viscoelastic dispersion data which are independent of the angular orientation of the sample. The test geometry is sufficiently sensitive to matrix changes to allow its use for postcuring, humidity, crosslink density, and other matrix change studies. Test results are presented for a carbon-epoxy laminate.
Results from beam tests of MEGA's low-mass, high-rate cylindrical MWPCs
Stanislaus, S.; Armijo, V.; Black, J.K.; Bolton, R.D.; Carius, S.; Cooper, M.D.; Espinoza, C.; Hart, G.; Hogan, G.; Gonzales, A.; Mischke, R.E.; Piilonen, L.E.; Sandoval, J.; Schilling, S.; Sena, J.; Suazo, G.; Szymanski, J.J.; Whitehouse, D.A.; Wilkinson, C.A.; Fisk, R.; Koetke, D.D.; Manweiler, R.W.; Jui, C.C.
1991-01-01
One of the leading experimental projects at LAMPF has been the MEGA experiment. This is an experiment to search for the rare decay μ → eγ with a sensitivity of 10 -13 . A prime component of this project has been the design and construction of high-rate, low mass MWPCs for the tracking of positrons from muon decay. With rate capabilities of 2 x 10 4 e + /mm 2 /s and a thickness of 3 x 10 -4 radiation lengths, these chambers are state-of-the-art cylindrical MWPCs. Cylindrical chambers of this size (0.9 m 2 ) and thinness have never been previously constructed. The MEGA project at LAMPF has recently succeeded in building chambers with these necessary performance characteristics as demonstrated by data taken from muon decays, cosmic rays, and sources
De-An, Pan; Shen-Gen, Zhang; Jian-Jun, Tian; Li-Jie, Qiao; Jun-Sai, Sun; Volinsky, Alex A.
2010-01-01
Current–voltage measurements obtained from lead zirconate titanate/nickel bilayered hollow cylindrical magnetoelectric composite showed that a sinusoidal current applied to the copper coil wrapped around the hollow cylinder circumference induces voltage across the lead zirconate titanate layer thickness. The current–voltage coefficient and the maximum induced voltage in lead zirconate titanate at 1 kHz and resonance (60.1 kHz) frequencies increased linearly with the number of the coil turns and the applied current. The resonance frequency corresponds to the electromechanical resonance frequency. The current–voltage coefficient can be significantly improved by optimizing the magnetoelectric structure geometry and/or increasing the number of coil turns. Hollow cylindrical lead zirconate titanate/nickel structures can be potentially used as current sensors. (condensed matter: electronic structure, electrical, magnetic, and optical properties)
Radiation history and energy coupling to cylindrical targets on the Z machine
Aubrey, J.; Bowers, R.L.; Peterson, D.L.; Chandler, G.A.; Derzon, M.S.; Nash, T.J.; Fehl, D.L.
1999-01-01
A series of experiments have been designed and fielded on the Sandia Z machine to characterize the radiation history and energy coupling to cylindrical targets embedded in a central cushion. The implosion of, a nested wire array, which has produced temperatures of 230 eV in a central cushion (Flying Radiation Case/Dynamic Hohlraum), is used as a source, in the calculations, to drive ablative shocks in cylindrical shells. These shells have initial radii of 1 mm, wall thickness of 20 to 50 microm and are embedded in low density foam. Simulations of the radiation environment in the cushion, including the radiation pre-pulse associated with the run-in of the load plasma and the energy coupling to the target will be presented. The dynamics of the imploding plasma, its evolution near the axial aperture and its effects on diagnostic access will also be considered
The size-dependent vibration of embedded magneto-electro-elastic cylindrical nanoshells
Ke, Liao-Liang; Wang, Yue-Sheng; Yang, Jie; Kitipornchai, Sritawat
2014-01-01
Based on the nonlocal Love’s shell theory, this paper develops an embedded magneto-electro-elastic (MEE) cylindrical nanoshell model. This model incorporates effects of the small scale parameter and thermo-electro-magnetic loadings. The surrounding elastic medium is described as the Winkler model characterized by the spring. By using this model and the Hamilton principle, the governing equations and boundary conditions are derived for free vibration of the embedded MEE cylindrical nanoshells. The Navier’s method is first utilized to obtain the analytical solution for the simply supported MEE nanoshell. Then, numerical solutions for MEE nanoshells under various boundary conditions are obtained by using the differential quadrature (DQ) method. A detailed parametric study is conducted to highlight the influences of the nonlocal parameter, temperature rise, external electric potential, external magnetic potential, spring constant, radius-to-thickness ratio and length-to-radius ratio on natural frequencies of MEE nanoshells. (paper)
Salvatore Brischetto
2014-01-01
equilibrium written in orthogonal curvilinear coordinates for the free vibrations of simply supported structures. These equations consider an exact geometry for shells without simplifications. The main novelty is the possibility of a general formulation for different geometries. The equations written in general orthogonal curvilinear coordinates allow the analysis of spherical shell panels and they automatically degenerate into cylindrical shell panel, cylindrical closed shell, and plate cases. Results are proposed for isotropic and orthotropic structures. An exhaustive overview is given of the vibration modes for a number of thickness ratios, imposed wave numbers, geometries, embedded materials, and angles of orthotropy. These results can also be used as reference solutions to validate two-dimensional models for plates and shells in both analytical and numerical form (e.g., closed solutions, finite element method, differential quadrature method, and global collocation method.
Charge distribution dependency on gap thickness of CMS endcap RPC
Park, Sung Keun
2016-01-01
We present a systematic study of charge distribution dependency of CMS Resistive Plate Chamber (RPC) on gap thickness.Prototypes of double-gap with five different gap thickness from 1.8mm to 1.0mm in 0.2mm steps have been built with 2mm thick phenolic high-pressure-laminated (HPL) plates. The charges of cosmic-muon signals induced on the detector strips are measured as a function of time using two four-channel 400-MHz fresh ADCs. In addition, the arrival time of the muons and the strip cluster sizes are measured by digitizing the signal using a 32-channel voltage-mode front-end-electronics and a 400-MHz 64-channel multi-hit TDC. The gain and the input impedance of the front-end-electronics were 200mV/mV and 20 Ohm, respectively.
Analysis of a cylindrical shell vibrating in a cylindrical fluid region
Chung, H.; Turula, P.; Mulcahy, T.M.; Jendrzejczyk, J.A.
1976-08-01
Analytical and experimental methods are presented for evaluating the vibration characteristics of cylindrical shells such as the thermal liner of the Fast Flux Test Facility (FFTF) reactor vessel. The NASTRAN computer program is used to calculate the natural frequencies, mode shapes, and response to a harmonic loading of a thin, circular cylindrical shell situated inside a fluid-filled rigid circular cylinder. Solutions in a vacuum are verified with an exact solution method and the SAP IV computer code. Comparisons between analysis and experiment are made, and the accuracy and utility of the fluid-solid interaction package of NASTRAN is assessed
Moon, Haksu; Teixeira, Fernando L.; Donderici, Burkay
2014-09-01
Computation of electromagnetic fields due to point sources (Hertzian dipoles) in cylindrically stratified media is a classical problem for which analytical expressions of the associated tensor Green's function have been long known. However, under finite-precision arithmetic, direct numerical computations based on the application of such analytical (canonical) expressions invariably lead to underflow and overflow problems related to the poor scaling of the eigenfunctions (cylindrical Bessel and Hankel functions) for extreme arguments and/or high-order, as well as convergence problems related to the numerical integration over the spectral wavenumber and to the truncation of the infinite series over the azimuth mode number. These problems are exacerbated when a disparate range of values is to be considered for the layers' thicknesses and material properties (resistivities, permittivities, and permeabilities), the transverse and longitudinal distances between source and observation points, as well as the source frequency. To overcome these challenges in a systematic fashion, we introduce herein different sets of range-conditioned, modified cylindrical functions (in lieu of standard cylindrical eigenfunctions), each associated with nonoverlapped subdomains of (numerical) evaluation to allow for stable computations under any range of physical parameters. In addition, adaptively-chosen integration contours are employed in the complex spectral wavenumber plane to ensure convergent numerical integration in all cases. We illustrate the application of the algorithm to problems of geophysical interest involving layer resistivities ranging from 1000 Ω m to 10-8 Ω m, frequencies of operation ranging from 10 MHz down to the low magnetotelluric range of 0.01 Hz, and for various combinations of layer thicknesses.
Tensile strength of glulam laminations of Nordic spruce
Hoffmeyer, Preben; Bräuner, Lise; Boström, Lars
1999-01-01
Design of glulam according to the European timber code Eurocode 5 is based on the standard document prEN1194 , according to which glulam beam strength is to be established either by full scale testing or by calculation. The calculation must be based on a knowledge of lamination tensile strength....... This knowledge may be obtained either by adopting a general rule that the characteristic tensile strength is sixty percent of the characteristic bending strength, or by performing tensile tests on an adequate number of laminations representative of the whole population. The present paper presents...... an investigation aimed at establishing such an adequate experimental background for the assignment of strength classes for glulam made of visually strength graded laminations from Nordic sawmills. The investigation includes more than 1800 boards (laminations) of Norway spruce (Picea abies) sampled from eight...
Fatigue damage mechanics of notched graphite-epoxy laminates
Spearing, Mark; Beaumont, Peter W. R.; Ashby, Michael F.
A modeling approach is presented that recognizes that the residual properties of composite laminates after any form of loading depend on the damage state. Therefore, in the case of cyclic loading, it is necessary to first derive a damage growth law and then relate the residual properties to the accumulated damage. The propagation of fatigue damage in notched laminates is investigated. A power law relationship between damage growth and the strain energy release rate is developed. The material constants used in the model have been determined in independent experiments and are invariant for all the layups investigated. The strain energy release rates are calculated using a simple finite element representation of the damaged specimen. The model is used to predict the effect of tension-tension cyclic loading on laminates of the T300/914C carbon-fiber epoxy system. The extent of damage propagation is successfully predicted in a number of cross-ply laminates.
Climbing ripple structure and associated storm-lamination from a ...
Pranhita–Godavari Valley, south India, displays well developed climbing ripple lamination and ... sedimentary environments, such as river flood .... Sediment, sequence and facies ..... tic Archaean Witwatersrand Supergroup, South Africa;.
Finite elements modeling of delaminations in composite laminates
Gaiotti, m.; Rizzo, C.M.; Branner, Kim
2011-01-01
of the buckling strength of composite laminates containing delaminations. Namely, non-linear buckling and post-buckling analyses are carried out to predict the critical buckling load of elementary composite laminates affected by rectangular delaminations of different sizes and locations, which are modelled......The application of composite materials in many structures poses to engineers the problem to create reliable and relatively simple methods, able to estimate the strength of multilayer composite structures. Multilayer composites, like other laminated materials, suffer from layer separation, i.......e., delaminations, which may affect the stiffness and stability of structural components. Especially deep delaminations in the mid surface of laminates are expected to reduce the effective flexural stiffness and lead to collapse, often due to buckling behaviour. This paper deals with the numerical modelling...
Pliocene benthonic foraminifera from homogeneous and laminated marls on Crete
Jonkers, H.A.
1984-01-01
In the Pliocene, the paleogeography of central Crete consisted of a number of basins which were filled by predominantly marly sediments. In the sedimentary sequence numerous laminated sapropelic intercalations can be observed. At a higher stratigraphic level diatomaceous laminites appear.
Modal analysis of pre and post impacted nano composite laminates
R. Velmurugan
Full Text Available Modal analysis is carried out on pre and post impacted nano composite laminates. The laminates are prepared using 3, 5 and 8 layers of 610gsm glass woven roving mats(WRM with epoxy resin and montmorillonite(MMT clay content is varied from 1% to 5%. Impulse hammer technique is used to find natural frequency and damping factor of laminates. Medium velocity impact tests are conducted by using a gas gun. The vibration responses of natural frequency and damping factor are obtained and are studied for laminates with all edges clamped boundary conditions. Results show considerable improvement in natural frequency and damping factor due to nano clay addition. It is also seen that the nano clay controls the delamination due to impact loading.
Fast, inexpensive, diffraction limited cylindrical microlenses
Synder, J.J.; Reichert, P.
1991-01-01
We have developed a technique for fabricating fast, well corrected cylindrical microlenses. With this technique we have made a number of different microlenses with dimensions and focal lengths in the range of few hundred μm, and diffraction limited numerical apertures as high as 0.9. The microlenses are specifically designed for applications where they can increase the radiance or otherwise enhance the optical characteristics of laser diode light. The fabrication method we use is very versatile, and the microlenses produced this way would be very inexpensive in production quantities. 6 refs., 4 figs
History of the small cylindrical melter
Allen, T.L.; Iverson, D.C.; Plodinec, M.J.
1985-08-01
The small cylindrical melter (SCM) was designed to provide engineering data useful for operation and design of full-scale glass melters for vitrification of high-level radioactive waste. This melter was part of the research and development program for the Defense Waste Processing Facility (DWPF) at the Savannah River Plant (SRP). Extensive corrosion testing of melter materials of construction (Monofrax K3, Inconel 690), simulated radioactive waste glass characterization, and melter component development were conducted in support of the DWPF full-scale melter design. 66 figs., 14 tabs
Acoustic propagation mode in a cylindrical plasma
Ishida, Yoshio; Idehara, Toshitaka; Inada, Hideyo
1975-01-01
The sound velocity in a cylindrical plasma produced by a high frequency discharge is measured by an interferometer system. The result shows that the acoustic wave guide effect does exist in a neutral gas and in a plasma. It is found that the wave propagates in the mode m=2 in a rigid boundary above the cut-off frequency fsub(c) and in the mode m=0 below fsub(c). Because the mode m=0 is identical to a plane wave, the sound velocity in free space can be evaluated exactly. In the mode m=2, the sound velocity approaches the free space value, when the frequency increases sufficiently. (auth.)
Cylindrical ionization chamber with compressed krypton
Kuz'minov, V.V.; Novikov, V.M.; Pomanskii, A.A.; Pritychenko, B.V.; Viyar, J.; Garcia, E.; Morales, A.; Morales, J.; Nunes-Lagos, R.; Puimedon, J.; Saens, K.; Salinas, A.; Sarsa, M.
1993-01-01
A cylindrical ionization chamber with a grid is used to search for double positron decay and atomic electron conversion to a positron in 78 Kr. Krypton is the working gas material of the chamber. The spectrometric characteristics of the chamber filled with krypton and xenon are presented. The energy resolution is 2.1% for an energy of 1.84 MeV (the source of γ-quanta is 88 Y) when the chamber is filled with a mixture of Kr+0.2% H 2 under a pressure of 25 atm
Cullet Manufacture Using the Cylindrical Induction Melter
Miller, D. H.
2000-01-01
The base process for vitrification of the Am/Cm solution stored in F-canyon uses 25SrABS cullet as the glass former. A small portion of the cullet used in the SRTC development work was purchased from Corning while the majority was made in the 5 inch Cylindrical Induction Melter (CIM5). Task 1.01 of TTR-NMSS/SE-006, Additional Am-Cm Process Development Studies, requested that a process for the glass former (cullet) fabrication be specified. This report provides the process details for 25SrAB cullet production thereby satisfying Task 1.01
Stability analysis of cylindrical Vlasov equilibria
Short, R.W.
1979-01-01
A general method of stability analysis is described which may be applied to a large class of such problems, namely those which are described dynamically by the Vlasov equation, and geometrically by cylindrical symmetry. The method is presented for the simple case of the Vlasov-Poisson (electrostatic) equations, and the results are applied to a calculation of the lower-hybrid-drift instability in a plasma with a rigid rotor distribution function. The method is extended to the full Vlasov-Maxwell (electromagnetic) equations. These results are applied to a calculation of the instability of the extraordinary electromagnetic mode in a relativistic E-layer interacting with a background plasma
Enhanced Performance of Cylindrical Hall Thrusters
Raitses, Y.; Smirnov, A.; Fisch, N.J.
2007-01-01
The cylindrical thruster differs significantly in its underlying physical mechanisms from the conventional annular Hall thruster. It features high ionization efficiency, quiet operation, ion acceleration in a large volume-to-surface ratio channel, and performance comparable with the state-of-the-art conventional Hall thrusters. Very significant plume narrowing, accompanied by the increase of the energetic ion fraction and improvement of ion focusing, led to 50-60% increase of the thruster anode efficiency. These improvements were achieved by overrunning the discharge current in the magnetized thruster plasma
Waves in inhomogeneous plasma of cylindrical geometry
Rebut, P.H.
1966-01-01
The conductivity tensor of a hot and inhomogeneous plasma has been calculated for a cylindrical geometry using Vlasov equations. The method used consists in a perturbation method involving the first integrals of the unperturbed movement. The conductivity tensor will be particularly useful for dealing with stability problems. In the case of a cold plasma the wave equation giving the electric fields as a function of the radius is obtained. This equation shows the existence of resonant layers which lead to an absorption analogous to the Landau absorption in a hot plasma. (author) [fr
Subclinical Laminitis in Dairy Cattle: 205 Selected Cases
BAKIR, Ali BELGE Bahtiyar
2005-01-01
The economic importance of lameness in dairy cattle has newly been recognized in Turkey. Lameness incidence in Turkey has been reported to be between 13% and 58%, which is similar to that of other countries where 4% and 55% incidence rates have been reported. The objective of this study was to determine the prevalence of sole lesions associated with subclinical laminitis in the hooves of dairy cattle in Van, Turkey. The risk factors for subclinical laminitis are proposed and discussed. The so...
Dowelled structural connections in laminated bamboo and timber
Reynolds, Thomas Peter; Sharma, Bhavna; Harries, Kent; Ramage, Michael Hector
2015-01-01
Structural sections of laminated bamboo can be connected using methods common in timber engineering, however the different material properties of timber and laminated bamboo suggest that the behaviour of connections in the two materials would not be the same. This study investigates the dowelled connection, in which a connector is passed through a hole in the material, and load is resisted by shear in the connector and embedment into the surrounding material. Steel dowels were used in a conne...
Laminitis in a mature elk hind (Cervus elaphus)
Gray, Heather E.; Card, Claire; Baptiste, Keith E.
2001-01-01
Laminitis should be considered as a differential diagnosis in elk presenting with shifting leg lameness, reluctance to move, recumbency and hoof wall ridging. Eliminating the underlying cause and corrective trimming lead to a good prognosis for recovery.......Laminitis should be considered as a differential diagnosis in elk presenting with shifting leg lameness, reluctance to move, recumbency and hoof wall ridging. Eliminating the underlying cause and corrective trimming lead to a good prognosis for recovery....
Retortable Laminate/Polymeric Food Tubes for Specialized Feeding
2012-06-01
Report STP #3010 Results and Accomplishments (June 2010 – June 2012) Report No: FTR 303 CDRL Sequence: A003 June 2012 CORANET CONTRACT #: SP4701-08-D...June 2010 - June 2012 Retortable Laminate/Polymeric Food Tubes for Specialized Feeding - STP # 3010 SP4701-08-D-0004 MANTECH (0708011S) CORANET A003...on commercial off-the-shelf materials and not military unique. A market survey of commercially available laminated tubes revealed that they are all
Electroplating moulds using dry film thick negative photoresist
Kukharenka, E.; Farooqui, M. M.; Grigore, L.; Kraft, M.; Hollinshead, N.
2003-07-01
This paper reports on progress on the feasibility of fabricating moulds for electroplating using Ordyl P-50100 (negative) acrylate polymer based dry film photoresist, commercially available from Elga Europe (http://www.elgaeurope.it). We used this photoresist as an alternative to SU8 negative epoxy based photoresist, which is very difficult to process and remove after electroplating (Lorenz et al 1998 Microelectron. Eng. 41/42 371-4, Eyre et al 1998 Proc. MEMS'98 (Heidelberg) (Piscataway, NJ: IEEE) pp 218-22). Ordyl P-50100 is easy to work with and can be easily removed after processing. A single layer of Ordyl P-50100 was deposited by lamination up to 20 µm thickness. Thicker layers (200 µm and more) can be achieved with multilayer lamination using a manual laminator. For our applications we found that Ordyl P-50100 dry film photoresist is a very good alternative to SU8 for the realization of 100 µm high moulds. The results presented will open up new possibilities for low-cost LIGA-type processes for MEMS applications.
Mohammed, I.; Abu Talib, A. R.; Sultan, M. T. H.; Saadon, S.
2017-12-01
Aerospace and other industries use fibre metal laminate composites extensively due to their high specific strength, stiffness and fire resistance, in addition to their capability to be tailored into different forms for specific purposes. The behaviours of such composites under impact loading is another factor to be considered due to the impacts that occur in take-off, landing, during maintenance and operations. The aim of the study is to determine the specific perforation energy and impact strength of the fibre metal laminates of different layering pattern of carbon fibre reinforced aluminium alloy and hybrid laminate composites of carbon fibre and natural fibres (kenaf and flax). The composites are fabricated using the hand lay-up method in a mould with high bonding polymer matrix and compressed by a compression machine, cured at room temperature for one day and post cure in an oven for three hours. The impact tests are conducted using a gun tunnel system with a flat cylindrical bullet fired using a helium gas at a distance of 14 inches to the target. Impact and residual velocity of the projectile are recorded by high speed video camera. Specific perforation energy of carbon fibre reinforced aluminium alloy (CF+AA) for both before and after fire test are higher than the specific perforation energy of the other composites considered before and after fire test respectively. CF +AA before fire test is 55.18% greater than after. The same thing applies to impact strength of the composites where CF +AA before the fire test has the highest percentage of 11.7%, 50.0% and 32.98% as respectively compared to carbon fibre reinforced aluminium alloy (CARALL), carbon fibre reinforced flax aluminium alloy (CAFRALL) and carbon fibre reinforced kenaf aluminium alloy (CAKRALL), and likewise for the composites after fire test. The considered composites in this test can be used in the designated fire zone of an aircraft engine to protect external debris from penetrating the engine
Experimental Assessment of Tensile Failure Characteristic for Advanced Composite Laminates
Lee, Myoung Keon [Agency for Defense Development, Daejeon (Korea, Republic of); Lee, Jeong Won; Yoon, Dong Hyun; Kim, Jae Hoon [Chungnam Nat’l Univ., Daejeon (Korea, Republic of)
2017-10-15
In recent years, major airplane manufacturers have been using the laminate failure theory to estimate the strain of composite structures for airplanes. The laminate failure theory uses the failure strain of the laminate to analyze composite structures. This paper describes a procedure for the experimental assessment of laminate tensile failure characteristics. Regression analysis was used as the experimental assessment method. The regression analysis was performed with the response variable being the laminate failure strain and with the regressor variables being two-ply orientation (0° and ±45°) variables. The composite material in this study is a carbon/epoxy unidirectional (UD) tape that was cured as a pre-preg at 177°C(350°F). A total of 149 tension tests were conducted on specimens from 14 distinct laminates that were laid up at standard angle layers (0°, 45°, -45°, and 90°). The ASTM-D-3039 standard was used as the test method.
Experimental Assessment of Tensile Failure Characteristic for Advanced Composite Laminates
Lee, Myoung Keon; Lee, Jeong Won; Yoon, Dong Hyun; Kim, Jae Hoon
2017-01-01
In recent years, major airplane manufacturers have been using the laminate failure theory to estimate the strain of composite structures for airplanes. The laminate failure theory uses the failure strain of the laminate to analyze composite structures. This paper describes a procedure for the experimental assessment of laminate tensile failure characteristics. Regression analysis was used as the experimental assessment method. The regression analysis was performed with the response variable being the laminate failure strain and with the regressor variables being two-ply orientation (0° and ±45°) variables. The composite material in this study is a carbon/epoxy unidirectional (UD) tape that was cured as a pre-preg at 177°C(350°F). A total of 149 tension tests were conducted on specimens from 14 distinct laminates that were laid up at standard angle layers (0°, 45°, -45°, and 90°). The ASTM-D-3039 standard was used as the test method.
Fatigue qualification of high thickness composite rotor components
Raggi, M.; Mariani, U.; Zaffaroni, G.
Fatigue qualification aspects of composite rotor components are presented according with the safe life procedure usually applied by helicopter manufacturers. Test activities are identified at three levels of specimen complexity: coupon, structural element and full scale component. Particular attention is given to high thickness laminates qualification as far as environmental exposure is concerned. A practical approach for an accelerated conditioning procedure is described. The application to a main rotor tension link is presented showing the negligible effect of the moisture absorption on its fatigue strength.
Rucinski, R.
1998-01-01
The preshower lead thickness applied to the outside of D-Zero's superconducting solenoid vacuum shell was measured at the time of application. This engineering documents those thickness measurements. The lead was ordered in sheets 0.09375-inch and 0.0625-inch thick. The tolerance on thickness was specified to be +/- 0.003-inch. The sheets all were within that thickness tolerance. The nomenclature for each sheet was designated 1T, 1B, 2T, 2B where the numeral designates it's location in the wrap and 'T' or 'B' is short for 'top' or 'bottom' half of the solenoid. Micrometer measurements were taken at six locations around the perimeter of each sheet. The width,length, and weight of each piece was then measured. Using an assumed pure lead density of 0.40974 lb/in 3 , an average sheet thickness was calculated and compared to the perimeter thickness measurements. In every case, the calculated average thickness was a few mils thinner than the perimeter measurements. The ratio was constant, 0.98. This discrepancy is likely due to the assumed pure lead density. It is not felt that the perimeter is thicker than the center regions. The data suggests that the physical thickness of the sheets is uniform to +/- 0.0015-inch.
B. Attaf
2015-08-01
Full Text Available The present investigation aims to examine the influence of geometric ratios and fibre orientation on the natural frequencies of fibre-reinforced laminated composite plates using finite element method based on Yang’s theory and his collaborators. The transverse shear and rotatory inertia effects were taken into consideration in the developed Fortran computer program. It has been shown that the use of first-order displacement field provides the same accuracy as higher-order displacement field when the number of elements representing the plate structure is increased (refined mesh. However, poor precision may appear for plates with high thickness-to-side ratio h/a (thickness/side length. This discrepancy limits the application of the developed theory to thick plates (h/a<0.5. The various curves show the evolution of the dimensionless frequency (w* versus fibre orientation angle (q and illustrate the apparition of a “triple-point” phenomenon engendered by the increase of the plate aspect ratio a/b (length/width for a specific value of h/a. This point defines the maximum natural frequency and the associated fibre orientation. Also, results show that for high and/or low aspect ratios, the triple-point phenomenon does not occur. This latter is rapidly reached for thick plates than thin plates when the plate aspect ratio a/b is progressively increased.
Multimode interaction in axially excited cylindrical shells
Silva F. M. A.
2014-01-01
Full Text Available Cylindrical shells exhibit a dense frequency spectrum, especially near the lowest frequency range. In addition, due to the circumferential symmetry, frequencies occur in pairs. So, in the vicinity of the lowest natural frequencies, several equal or nearly equal frequencies may occur, leading to a complex dynamic behavior. So, the aim of the present work is to investigate the dynamic behavior and stability of cylindrical shells under axial forcing with multiple equal or nearly equal natural frequencies. The shell is modelled using the Donnell nonlinear shallow shell theory and the discretized equations of motion are obtained by applying the Galerkin method. For this, a modal solution that takes into account the modal interaction among the relevant modes and the influence of their companion modes (modes with rotational symmetry, which satisfies the boundary and continuity conditions of the shell, is derived. Special attention is given to the 1:1:1:1 internal resonance (four interacting modes. Solving numerically the governing equations of motion and using several tools of nonlinear dynamics, a detailed parametric analysis is conducted to clarify the influence of the internal resonances on the bifurcations, stability boundaries, nonlinear vibration modes and basins of attraction of the structure.
Experiment and Simulation Analysis on Noise Attenuation of Al/MF Cylindrical Shells
Bin Li
2017-01-01
Full Text Available For the issue concerning internal noise reduction of Al-made cylindrical shell structure, the noise control method of laying melamine foam (MF layer is adopted for in-shell noise attenuation experiments of Al and Al/MF cylindrical shells and corresponding internal noise response spectrograms are obtained. Based on the Virtual.Lab acoustics software, a finite element model is established for the analysis of noise in the Al/MF cylinder shell and numerical simulation computation is conducted for the acoustic mode and in-shell acoustic response; the correctness of the finite element model is verified via comparison with measured data. On this basis, influence rules of different MF laying rate and different laying thickness on acoustic cavity resonance response within the low and medium frequency range of 100–400 Hz are studied. It is indicated that noise reduction increases with MF laying rate, but the amplification decreases along with the rising of MF laying rate; noise reduction per unit thickness decreases with the increase of laying thickness, while noise reduction per unit area increases.
Laminate for use in instrument dials or hands and method of making laminate
Westland, J.M.; Crowther, A.
1981-01-01
A translucent sheet of PVC has a coating e.g. of black ink or luminous material, with apertures and optionally luminous or non-luminous indicia. Behind the apertures there are tritium-activated luminous indicia or markings which are covered by an opaque white sheet. A self-adhesive protective film may be temporarily applied to the coating. The laminated structure may be used for faces or hands in time-pieces or other instruments. The use of the white sheet and protective film prevents operatives coming into contact with luminous materials. (author)
Note: Electrochemical etching of cylindrical nanoprobes using a vibrating electrolyte
Wang, Yufeng; Zeng, Yongbin; Qu, Ningsong; Zhu, Di
2015-01-01
An electrochemical etching process using a vibrating electrolyte of potassium hydroxide to prepare tungsten cylindrical nanotips is developed. The vibrating electrolyte eases the effects of a diffusion layer and extends the etching area, which aid in the production of cylindrical nanotips. Larger amplitudes and a vibration frequency of 35 Hz are recommended for producing cylindrical nanotips. Nanotips with a tip radius of approximately 43 nm and a conical angle of arctan 0.0216 are obtained
Rassmann, S.; Paskaramoorthy, R.; Reid, R.G.
2011-01-01
The objective of this study is to compare the mechanical and water absorption properties of kenaf (Hibiscus cannabinus L.) fibre reinforced laminates made of three different resin systems. The use of different resin systems is considered so that potentially complex and expensive fibre treatments are avoided. The resin systems used include a polyester, a vinyl ester and an epoxy. Laminates of 15%, 22.5% and 30% fibre volume fraction were manufactured by resin transfer moulding. The laminates were tested for strength and modulus under tensile and flexural loading. Additionally, tests were carried out on laminates to determine the impact energy, impact strength and water absorption. The results revealed that properties were affected in markedly different ways by the resin system and the fibre volume fraction. Polyester laminates showed good modulus and impact properties, epoxy laminates displayed good strength values and vinyl ester laminates exhibited good water absorption characteristics. Scanning electron microscope studies show that epoxy laminates fail by fibre fracture, polyester laminates by fibre pull-out and vinyl ester laminates by a combination of the two. A comparison between kenaf and glass laminates revealed that the specific tensile and flexural moduli of both laminates are comparable at the volume fraction of 15%. However, glass laminates have much better specific properties than the kenaf laminates at high fibre volume fractions for all three resins used.
Electron beam curable polymer thick film
Nagata, Hidetoshi; Kobayashi, Takashi
1988-01-01
Currently, most printed circuit boards are produced by the selective etching of copper clads laminated on dielectric substrates such as paper/phenolic resion or nonwoven glass/epoxy resin composites. After the etchig, various components such as transistors and capacitors are mounted on the boards by soldering. But these are troublesome works, therefore, as an alternative, printing method has been investigated recently. In the printing method, conductor circuits and resistors can be made by printing and curing of the specially prepared paste on dielectric substrates. In the near future, also capacitors are made by same method. Usually, conductor paste, resistor paste and dielectric paste are employed, and in this case, the printing is screen printing, and the curing is done thermally. In order to avoid heating and the deterioration of substrates, attention was paid to electron beam curing, and electron beam curable polymer thick film system was developed. The electron beam curable paste is the milled mixture of a filler and an electron beam curable binder of oligomer/monomer. The major advantage of electron beam curable polymer thick film, the typical data of a printed resistor of this type and its trial are reported. (K.I.)
Education and "Thick" Epistemology
Kotzee, Ben
2011-01-01
In this essay Ben Kotzee addresses the implications of Bernard Williams's distinction between "thick" and "thin" concepts in ethics for epistemology and for education. Kotzee holds that, as in the case of ethics, one may distinguish between "thick" and "thin" concepts of epistemology and, further, that this distinction points to the importance of…
Hoffheins, Barbara S.; Lauf, Robert J.
1995-01-01
A thick film hydrogen sensor element includes an essentially inert, electrically-insulating substrate having deposited thereon a thick film metallization forming at least two resistors. The metallization is a sintered composition of Pd and a sinterable binder such as glass frit. An essentially inert, electrically insulating, hydrogen impermeable passivation layer covers at least one of the resistors.
Magnetostatic interactions and forces between cylindrical permanent magnets
Vokoun, David; Beleggia, Marco; Heller, Ludek; Sittner, Petr
2009-01-01
Permanent magnets of various shapes are often utilized in magnetic actuators, sensors or releasable magnetic fasteners. Knowledge of the magnetic force is required to control devices reliably. Here, we introduce an analytical expression for calculating the attraction force between two cylindrical permanent magnets on the assumption of uniform magnetization. Although the assumption is not fulfilled exactly in cylindrical magnets, we obtain a very good agreement between the calculated and measured forces between two identical cylindrical magnets and within an array of NdFeB cylindrical magnets.
Drabczyk, Kazimierz, E-mail: kazimierz.drabczyk@wp.pl [Institute of Metallurgy and Materials Science, 25 Reymonta St., 30-059 Krakow (Poland); Panek, Piotr [Institute of Metallurgy and Materials Science, 25 Reymonta St., 30-059 Krakow (Poland)
2012-09-01
In more than 80% of the worldwide photovoltaic (PV) modules, mostly very fragile and 200 {mu}m thick, crystalline silicon solar cells are encapsulated into ethylene-vinyl acetate (EVA) foils, which bond the module components together, provide physical protection, electrical insulation and a barrier for moisture ingress. The understanding of what can happen with EVA during its transport, storage and lamination process is necessary to optimize the quality of the PV module for its long exposure to outdoor weather conditions. Achieving a proper cross-link density of over 70%, it is essential to overcome the cold flow of EVA and to make the module durable. In this work, the feasibility of the use of differential scanning calorimetry (DSC) compared with the solvent extraction (SE) method by toluene were evaluated in order to provide structural information on the EVA curing kinetics and the cross-link density. DSC tests were performed on a DTA DuPont1600 tester. The temperature range for the test was from -50 Degree-Sign C to 200 Degree-Sign C, with the heating rate of 10 Degree-Sign C/min, and the endothermic and exothermic peaks were evaluated. Toluene solvent extractions were performed on the same set of samples that were analyzed by DSC. The measured cross-link density shows a direct dependence on the pre-lamination conditions of EVA, which is in good agreement with the data obtained with the DSC method.
Drabczyk, Kazimierz; Panek, Piotr
2012-01-01
In more than 80% of the worldwide photovoltaic (PV) modules, mostly very fragile and 200 μm thick, crystalline silicon solar cells are encapsulated into ethylene-vinyl acetate (EVA) foils, which bond the module components together, provide physical protection, electrical insulation and a barrier for moisture ingress. The understanding of what can happen with EVA during its transport, storage and lamination process is necessary to optimize the quality of the PV module for its long exposure to outdoor weather conditions. Achieving a proper cross-link density of over 70%, it is essential to overcome the cold flow of EVA and to make the module durable. In this work, the feasibility of the use of differential scanning calorimetry (DSC) compared with the solvent extraction (SE) method by toluene were evaluated in order to provide structural information on the EVA curing kinetics and the cross-link density. DSC tests were performed on a DTA DuPont1600 tester. The temperature range for the test was from −50 °C to 200 °C, with the heating rate of 10 °C/min, and the endothermic and exothermic peaks were evaluated. Toluene solvent extractions were performed on the same set of samples that were analyzed by DSC. The measured cross-link density shows a direct dependence on the pre-lamination conditions of EVA, which is in good agreement with the data obtained with the DSC method.
Sensitivity Analysis of a CPAM Inverse Algorithm for Composite Laminates Characterization
Farshid Masoumi
2017-01-01
Full Text Available Using experimental data and numerical simulations, a new combined technique is presented for characterization of thin and thick orthotropic composite laminates. Four or five elastic constants, as well as ply orientation angles, are considered as the unknown parameters. The material characterization is first examined for isotropic plates under different boundary conditions to evaluate the method’s accuracy. The proposed algorithm, so-called CPAM (Combined Programs of ABAQUS and MATLAB, utilizes an optimization procedure and makes simultaneous use of vibration test data together with their corresponding numerical solutions. The numerical solutions are based on a commercial finite element package for efficiently identifying the material properties. An inverse method based on particle swarm optimization algorithm is further provided using MATLAB software. The error function to be minimized is the sum of squared differences between experimental and simulated data of eigenfrequencies. To evaluate the robustness of the model’s results in the presence of uncertainty and unwanted noises, a sensitivity analysis that employs Gaussian disorder model is directly applied to the measured frequencies. The results with high accuracy confirm the validity and capability of the present method in simultaneous determination of mechanical constants and fiber orientation angles of composite laminates as compared to prior methods.
Shade evaluation of ceramic laminates according to different try-in materials.
Lopes, Lawrence Gonzaga; Vaz, Maysa Magalhaes; de Magalhaes, Ana Paula Rodrigues; Cardoso, Paula Carvalho; de Souza, Joao Batista; de Torres, Erica Miranda
2014-01-01
The porcelain laminate replaces the visible portion of enamel with a ceramic, which is attached to the dental surface. To enhance cosmetic results, a preliminary color matching procedure is performed prior to cementing the veneers. This procedure can be performed using water, water-soluble gel, or try-in paste. The different shades of cement and try-in pastes are intended to obtain better color and esthetics of the final restoration. This study sought to evaluate the shade of ceramic veneers produced by different try-in materials. Forty bovine teeth and 40 ceramic discs (0.6 mm thick) were prepared. The samples were divided into 4 groups (n = 10). For Group 1 samples, no material was used between the tooth and the ceramic, Group 2 interposed samples with water, Group 3 used a water-soluble gel, and Group 4 used try-in paste (value 0). The color was measured with a spectrophotometer, obtaining L*, a*, and b* values to calculate the color difference (ΔE*). The data were subjected to normality tests and 1-way ANOVA. No significant statistical differences were found among the groups, indicating that the different try-in materials had similar effects on the color of the ceramic laminates.
Mechanical performance of carbon-epoxy laminates. Part I: quasi-static and impact bending properties
José Ricardo Tarpani
2006-06-01
Full Text Available In Part I of this study, quasi-static and impact bending properties of four aeronautical grade carbon-epoxy laminates have been determined and compared. Materials tested were unidirectional cross-ply (tape and bidirectional woven textile (fabric carbon fiber lay-up architectures, impregnated with standard and rubber-toughened resins, respectively, giving rise to 1.5 mm-thick laminates. Quasi-static mechanical properties assessed in transversal mode loading were modulus of elasticity, flexural strength and tenacity at the maximum load, whereas the net absorbed energy was determined under translaminar impact conditions. Two-dimensional woven carbon fiber reinforcements embedded in a rubber-toughened matrix presented the best mechanical performance under static loading. Under dynamic loading conditions, woven fiber fabric pre-forms were favorably sensitive to increasing impact energies regardless the nature of the employed epoxy resin. However, it was concluded that great care should be taken with this material within the low energy impact regimen.
Cylindrical vector beams of light from an electrically excited plasmonic lens
Cao, Shuiyan, E-mail: shuiyan.cao@u-psud.fr; Le Moal, Eric; Boer-Duchemin, Elizabeth; Dujardin, Gérald [Institut des Sciences Moléculaires d' Orsay, CNRS—Université Paris-Sud (UMR 8214), Orsay (France); Drezet, Aurélien; Huant, Serge [Université Grenoble Alpes, Inst. NEEL, F-38000 Grenoble (France); CNRS, Inst. NEEL, F-38042 Grenoble (France)
2014-09-15
The production of cylindrical vector beams from a low-energy, electric, microscale light source is demonstrated both experimentally and theoretically. This is achieved by combining a “plasmonic lens” with the ability to locally and electrically excite propagating surface plasmons on gold films. The plasmonic lens consists of concentric circular subwavelength slits that are etched in a thick gold film. The local excitation arises from the inelastic tunneling of electrons from the tip of a scanning tunneling microscope. We report on the emission of radially polarized beams with an angular divergence of less than ±4°.
The finite element simulation analysis research of 38CrSi cylindrical power spinning
Liang, Wei; Lv, Qiongying; Zhao, Yujuan; Lv, Yunxia
2018-01-01
In order to grope for the influence of the main cylindrical spinning process parameters on the spinning process, this paper combines with real tube power spinning process and uses ABAQUS finite element analysis software to simulate the tube power spinning process of 38CrSi steel materials, through the analysis of the stress, strain of the part forming process, analyzes the influence of the thickness reduction and the feed rate to the forming process, and analyzes the variation of the spinning force, finally determines the reasonable main spinning process parameters combination.
Acoustic radiation force on cylindrical shells in a plane standing wave
Mitri, F G
2005-01-01
In this paper, the radiation force per length resulting from a plane standing wave incident on an infinitely long cylindrical shell is computed. The cases of elastic and viscoelastic shells immersed in ideal (non-viscous) fluids are considered with particular emphasis on their thickness and the content of their interior hollow spaces. Numerical calculations of the radiation force function Y st are performed. The fluid-loading effect on the radiation force function curves is analysed as well. The results show several features quite different when the interior hollow space is changed from air to water. Moreover, the theory developed here is more general since it includes the results on cylinders
Three-dimensional vibrations of cylindrical elastic solids with V-notches and sharp radial cracks
McGee, O. G.; Kim, J. W.
2010-02-01
This paper provides free vibration data for cylindrical elastic solids, specifically thick circular plates and cylinders with V-notches and sharp radial cracks, for which no extensive previously published database is known to exist. Bending moment and shear force singularities are known to exist at the sharp reentrant corner of a thick V-notched plate under transverse vibratory motion, and three-dimensional (3-D) normal and transverse shear stresses are known to exist at the sharp reentrant terminus edge of a V-notched cylindrical elastic solid under 3-D free vibration. A theoretical analysis is done in this work utilizing a variational Ritz procedure including these essential singularity effects. The procedure incorporates a complete set of admissible algebraic-trigonometric polynomials in conjunction with an admissible set of " edge functions" that explicitly model the 3-D stress singularities which exist along a reentrant terminus edge (i.e., α>180°) of the V-notch. The first set of polynomials guarantees convergence to exact frequencies, as sufficient terms are retained. The second set of edge functions—in addition to representing the corner stress singularities—substantially accelerates the convergence of frequency solutions. This is demonstrated through extensive convergence studies that have been carried out by the investigators. Numerical analysis has been carried out and the results have been given for cylindrical elastic solids with various V-notch angles and depths. The relative depth of the V-notch is defined as (1- c/ a), and the notch angle is defined as (360°- α). For a very small notch angle (1° or less), the notch may be regarded as a "sharp radial crack." Accurate (four significant figure) frequencies are presented for a wide spectrum of notch angles (360°- α), depths (1- c/ a), and thickness ratios ( a/ h for plates and h/ a for cylinders). An extended database of frequencies for completely free thick sectorial, semi-circular, and
Sliding behaviors of elastic cylindrical tanks under seismic loading
Kobayashi, N.
1993-01-01
There is a paper that reports on the occurrence of sliding in several oil tanks on Alaskan earthquake of 1964. This incident appears to be in need of further investigation for the following reasons: First, in usual seismic designing of cylindrical tanks ('tanks'), sliding is considered to occur when the lateral inertial force exceeds the static friction force. When the tank in question can be taken as a rigid body, this rule is known to hold true. If the tank is capable of undergoing a considerable amount of elastic deformation, however, its applicability has not been proved. Second, although several studies have been done on the critical conditions for static sliding the present author is unaware of like ones made on the dynamic sliding, except for the pioneering work of Sogabe, in which they have empirically indicated possibility of sliding to occur under the force of sloshing. Third, this author has shown earlier on that tanks, if not anchored properly, will start rocking, inducing uplifting of the base plate, even at a relatively small seismic acceleration of 10 gal or so. The present study has been conducted with these observations for the background. Namely, based on a notion that elastic deformation given rise to by rocking oscillation should be incorporated as an important factor in any set of critical conditions for the onset of sliding, a series of shaking table experiments were performed for rigid steel block to represent the rigid tanks ('rigid model') and a model tank having a same sort of plate thickness-to-diameter ratio as industrial tanks to represent the elastic cylindrical tanks ('elastic model'). Following observations have been obtained for the critical condition of the onset of sliding: (1) sliding of rigid tanks will occur when the lateral force given rise to by oscillation exceeds the static, or the Coulombic, friction force. (2) if vertical oscillation is imposed on the lateral oscillation, the lateral force needed to induce sliding of a
Zhou, Hao-Miao; Li, Chao; Xuan, Li-Ming; Zhao, Ji-Xiang; Wei, Jing
2011-01-01
This paper analyzes the magnetoelectric (ME) response around the resonance frequency in the magnetostrictive/piezoelectric/magnetostrictive (MPM) magnetoelectric laminate composites. Following the equivalent circuit method and considering the mechanical loss, we select the nonlinear magnetostrictive constitutive model to present a novel explicit nonlinear expression for the resonant magnetoelectric (ME) coefficient of the magnetoelectric laminate composites. Compared with the experimental results, the predicted resonant ME coefficient of the explicit expression shows a good agreement both qualitatively and quantitatively. Also, when the electromechanical coupling factor of the piezoelectric material, k 31 p , is small, this explicit expression can be reduced to the existing model. On this basis, this paper considers and predicts the magnetoelectric conversion characteristics of the magnetoelectric laminate composites, calculates and analyzes the influences of the thickness ratio of magnetostrictive layer and piezoelectric material, bias magnetic field, and saturation magnetostrictive coefficient on the resonant ME coefficient. This research can provide a theoretical basis for the preparation of magnetoelectric devices with good magnetoelectric conversion characteristics, such as magnetoelectric sensors, energy harvesting transducers, microwave devices etc
Fazzini, Pablo Gabriel [Universidad Nacional de Mar del Plata (Argentina); [Consejo de Investigaciones Cientificas de la Provincia de Buenos Aires (CIC) (Argentina). Instituto de Investigaciones en Ciencia y Tecnologia de Materiales (INTEMA)]. E-mail: pgf@fi.mdp.edu.ar; Otegui, Jose Luis [Universidad Nacional de Mar del Plata (Argentina). Instituto de Investigaciones en Ciencia y Tecnologia de Materiales (INTEMA) (Argentina). CONICET; Motylicki, J [OLDELVAL S.A. (Argentina)
2003-07-01
Experimental results from seven hydrostatic tests on ex-service tubes from a 14'' diameter, 6.3 mm thickness ERW (electrical resistance seam welded) oil pipeline are presented. Lamination defects had been detected in these tracts by means of TFI in line inspection and the ultrasonic technique FAST. Of these tests, four were strain gauge instrumented. Five tubes failed in the ERW, burst pressures of defects in base material were larger. The fracture mechanics model of the most representative defect concludes that a lamination defect with an inclination of up to 3 mm in the radial direction, is not critical, test results show that this prediction is conservative. The largest laminations found in base material reduced burst pressure by less than 25%. On the contrary, defects that propagated in the ERW reduced burst resistance up to almost 50 %. These results show that the location of the defects is more important than size, the most important reason being the low toughness of the ERW. The results of this study confirm the validity of the restrictions that imposes section 8 of API 579. (author)
Teter, Andrzej; Kolakowski, Zbigniew
2018-01-01
The numerical modelling of a plate structure was performed with the finite element method and a one-mode approach based on Koiter's method. The first order approximation of Koiter's method enables one to solve the eigenvalue problem. The second order approximation describes post-buckling equilibrium paths. In the finite element analysis, the Lanczos method was used to solve the linear problem of buckling. Simulations of the non-linear problem were performed with the Newton-Raphson method. Detailed calculations were carried out for a short Z-column made of general laminates. Configurations of laminated layers were non-symmetric. Due to possibilities of its application, the general laminate is very interesting. The length of the samples was chosen to obtain the lowest value of local buckling load. The amplitude of initial imperfections was 10% of the wall thickness. Thin-walled structures were simply supported on both ends. The numerical results were verified in experimental tests. A strain-gauge technique was applied. A static compression test was performed on a universal testing machine and a special grip, which consisted of two rigid steel plates and clamping sleeves, was used. Specimens were obtained with an autoclave technique. Tests were performed at a constant velocity of the cross-bar equal to 2 mm/min. The compressive load was less than 150% of the bifurcation load. Additionally, soft and thin pads were used to reduce inaccuracy of the sample ends.
Fazzini, Pablo Gabriel [Universidad Nacional de Mar del Plata (Argentina)]|[Consejo de Investigaciones Cientificas de la Provincia de Buenos Aires (CIC) (Argentina). Instituto de Investigaciones en Ciencia y Tecnologia de Materiales (INTEMA)]. E-mail: pgf@fi.mdp.edu.ar; Otegui, Jose Luis [Universidad Nacional de Mar del Plata (Argentina). Instituto de Investigaciones en Ciencia y Tecnologia de Materiales (INTEMA) (Argentina). CONICET]. E-mail: jotegui@fi.mdp.edu.ar; Motylicki, J. [OLDELVAL S.A. (Argentina)]. E-mail: jmotylic@oldelval.com.ar
2003-07-01
Experimental results from seven hydrostatic tests on ex-service tubes from a 14'' diameter, 6.3 mm thickness ERW (electrical resistance seam welded) oil pipeline are presented. Lamination defects had been detected in these tracts by means of TFI in line inspection and the ultrasonic technique FAST. Of these tests, four were strain gauge instrumented. Five tubes failed in the ERW, burst pressures of defects in base material were larger. The fracture mechanics model of the most representative defect concludes that a lamination defect with an inclination of up to 3 mm in the radial direction, is not critical, test results show that this prediction is conservative. The largest laminations found in base material reduced burst pressure by less than 25%. On the contrary, defects that propagated in the ERW reduced burst resistance up to almost 50 %. These results show that the location of the defects is more important than size, the most important reason being the low toughness of the ERW. The results of this study confirm the validity of the restrictions that imposes section 8 of API 579. (author)
Guenanou, A.; Houmat, A.
2018-05-01
The optimum stacking sequence design for the maximum fundamental frequency of symmetrically laminated composite circular plates with curvilinear fibres is investigated for the first time using a layer-wise optimization method. The design variables are two fibre orientation angles per layer. The fibre paths are constructed using the method of shifted paths. The first-order shear deformation plate theory and a curved square p-element are used to calculate the objective function. The blending function method is used to model accurately the geometry of the circular plate. The equations of motion are derived using Lagrange's method. The numerical results are validated by means of a convergence test and comparison with published values for symmetrically laminated composite circular plates with rectilinear fibres. The material parameters, boundary conditions, number of layers and thickness are shown to influence the optimum solutions to different extents. The results should serve as a benchmark for optimum stacking sequences of symmetrically laminated composite circular plates with curvilinear fibres.
Ling, Chen; Sommer, André J
2015-06-01
Until recently, the analysis of polymer laminates using infrared microspectroscopy involved the painstaking separation of individual layers by dissection or by obtaining micrometer thin cross-sections. The latter usually requires the expertise of an individual trained in microtomy and even then, the very structure of the laminate could affect the outcome of the spectral results. The recent development of attenuated total internal reflection (ATR) infrared microspectroscopy imaging has provided a new avenue for the analysis of these multilayer structures. This report compares ATR infrared microspectroscopy imaging with conventional transmission infrared microspectroscopy imaging. The results demonstrate that the ATR method offers improved spatial resolution, eliminates a variety of competing optical processes, and requires minimal sample preparation relative to transmission measurements. These advantages were illustrated using a polymer laminate consisting of 11 different layers whose thickness ranged in size from 4-20 μm. The spatial resolution achieved by using an ATR-FTIR (Fourier transform infrared spectroscopy) imaging technique was diffraction limited. Contrast in the ATR images was enhanced by principal component analysis.
Focusing properties of cylindrical vector vortex beams
Xiaoqiang, Zhang; Ruishan, Chen; Anting, Wang
2018-05-01
In this paper, following Richards and Wolf vectorial diffraction theory, the focusing properties of cylindrical vector vortex beams (CVVB) are investigated, and a diffractive optical element (DOE) is designed to spatially modulate the amplitude of the CVVB. Simulated results show that the CVVB focused by an objective also carry orbital angular momentum (OAM), and the optical fields near the focal region can be modulated by changing the topological charge of the CVVB. We numerically simulate the focus properties of radially and azimuthally polarized beams with topological charge equal to 0, 1, 2 and 10 respectively. As a result, a dark channel with a length about 20 λ can be obtained. These new properties have the potential applications such as particle acceleration, optical trapping and material processing.
Indentation of Ellipsoidal and Cylindrical Elastic Shells
Vella, Dominic
2012-10-01
Thin shells are found in nature at scales ranging from viruses to hens\\' eggs; the stiffness of such shells is essential for their function. We present the results of numerical simulations and theoretical analyses for the indentation of ellipsoidal and cylindrical elastic shells, considering both pressurized and unpressurized shells. We provide a theoretical foundation for the experimental findings of Lazarus etal. [following paper, Phys. Rev. Lett. 109, 144301 (2012)PRLTAO0031-9007] and for previous work inferring the turgor pressure of bacteria from measurements of their indentation stiffness; we also identify a new regime at large indentation. We show that the indentation stiffness of convex shells is dominated by either the mean or Gaussian curvature of the shell depending on the pressurization and indentation depth. Our results reveal how geometry rules the rigidity of shells. © 2012 American Physical Society.
Confined detonations with cylindrical and spherical symmetry
Linan, A.; Lecuona, A.
1979-01-01
An imploding spherical or cylindrical detonation, starting in the interface of the detonantion with an external inert media, used as a reflector, creates on it a strong shock wave moving outward from the interface. An initially weak shock wave appears in the detonated media that travels toward the center, and it could reach the detonation wave, enforcing it in its process of implosion. To describe the fluid field, the Euler s equations are solved by means of expansions valid for the early stages of the process. Isentropic of the type P/pγ-K for the detonated and compressed inert media are used. For liquid or solid reflectors a more appropriate equation is used. (Author) 8 refs
Unbalanced Cylindrical Magnetron for Accelerating Cavities Coating
Rosaz, Guillaume; Calatroni, Sergio; Sublet, Alban; Tobarelli, Mauro
2016-01-01
We report in this paper the design and qualification of a cylindrical unbalanced magnetron source. The dedicated magnetic assemblies were simulated using a finite element model. A hall-effect magnetic probe was then used to characterize those assemblies and compared to the theoretical magnet profiles. These show a good agreement between the expected and actual values. the qualification of the different magnetic assemblies was then performed by measuring the ion flux density reaching the surface of the sample to be coated using a commercial retarding field energy analyzer. The strongest unbalanced configuration shows an increase from 0.016A.cm^-2 to 0.074A.cm^-2 of the ion flux density reaching the sample surface compared to the standard balanced configuration for a pressure 5.10^-3 mbar and a plasma source power of 300W.
Space charge emission in cylindrical diode
Torres-Córdoba, Rafael; Martínez-García, Edgar
2014-01-01
In this paper, a mathematical model to describe cylindrical electron current emissions through a physics approximation method is presented. The proposed mathematical approximation consists of analyzing and solving the nonlinear Poisson's equation, with some determined mathematical restrictions. Our findings tackle the problem when charge-space creates potential barrier that disable the steady-state of the beam propagation. In this problem, the potential barrier effects of electron's speed with zero velocity emitted through the virtual cathode happens. The interaction between particles and the virtual cathode have been to find the inter-atomic potentials as boundary conditions from a quantum mechanics perspective. Furthermore, a non-stationary spatial solution of the electrical potential between anode and cathode is presented. The proposed solution is a 2D differential equation that was linearized from the generalized Poisson equation. A single condition was used solely, throughout the radial boundary conditions of the current density formation
Analysis of a cylindrical imploding shock wave
Mishkin, E.A.; Fujimoto, Y.
1978-01-01
the self-similar solution of the gasdynamic equations of a strong cylindrical shock wave moving through an ideal gas, with γ = csub(p)/csub(v), is considered. These equations are greatly simplified following the transformation of the reduced velocity U 1 (xi) → U 1 = 1/2(γ + 1 ) (U + xi). The requirement of a single maximum pressure, dsub(xi)P = 0, leads to an analytical determination of the self-similarity exponent α(γ). For gases with γ = 2 + 3sup(1/2), this maximum ensues right at the shock front and the pressure distribution then decreases monotonically. The postulate of analyticity by Gelfand and Butler is shown to concur with the requirement dsub(xi)P 0. The saturated density of the gas left in the wake of the shock is computed and - U is shown to be the reduced velocity of sound at P = P sub(m). (author)
Cathode Effects in Cylindrical Hall Thrusters
Granstedt, E.M.; Raitses, Y.; Fisch, N. J.
2008-09-12
Stable operation of a cylindrical Hall thruster (CHT) has been achieved using a hot wire cathode, which functions as a controllable electron emission source. It is shown that as the electron emission from the cathode increases with wire heating, the discharge current increases, the plasma plume angle reduces, and the ion energy distribution function shifts toward higher energies. The observed effect of cathode electron emission on thruster parameters extends and clarifies performance improvements previously obtained for the overrun discharge current regime of the same type of thruster, but using a hollow cathode-neutralizer. Once thruster discharge current saturates with wire heating, further filament heating does not affect other discharge parameters. The saturated values of thruster discharge parameters can be further enhanced by optimal placement of the cathode wire with respect to the magnetic field.
Solar heat gain through vertical cylindrical glass
Kassem, M.A.; Kaseb, S.; El-Refaie, M.F. [Cairo Univ., Mechanical Power Engineering Dept., Cairo (Egypt)
1999-10-01
Spaces with nonplanar glazed envelopes are frequently encountered in contemporary buildings. Such spaces represent a problem when calculating the solar heat gain in the course of estimating the cooling or heating load; and hence, sizing of cooling or heating systems. The calculation, using the information currently available in the literature, is tedious and/or approximate. In the present work, the computational procedure for evaluating the solar heat gain to a space having a vertical cylindrical glass envelope is established, and, a computer program is coded to carry out the necessary computations and yield the results in a detailed usable form. The program is versatile and allows for the arbitrary variation of all pertinent parameters. (Author)
Solar heat gain through vertical cylindrical glass
Kassem, M.A.; Kaseb, S.; El-Refaie, M.F.
1999-01-01
Spaces with nonplanar glazed envelopes are frequently encountered in contemporary buildings. Such spaces represent a problem when calculating the solar heat gain in the course of estimating the cooling or heating load; and hence, sizing of cooling or heating systems. The calculation, using the information currently available in the literature, is tedious and/or approximate. In the present work, the computational procedure for evaluating the solar heat gain to a space having a vertical cylindrical glass envelope is established, and, a computer program is coded to carry out the necessary computations and yield the results in a detailed usable form. The program is versatile and allows for the arbitrary variation of all pertinent parameters. (Author)
Solar heat gain through vertical cylindrical glass
Kassem, M.A.; Kaseb, S.; El-Refaie, M.F. [Cairo Univ., Mechanical Power Engineering Dept., Cairo (Egypt)
1999-07-01
Spaces with nonplanar glazed envelopes are frequently encountered in contemporary buildings. Such spaces represent a problem when calculating the solar heat gain in the course of estimating the cooling or heating load; and hence, sizing of cooling or heating systems. The calculation, using the information currently available in the literature, is tedious and/or approximate. In the present work, the computational procedure for evaluating the solar heat gain to a space having a vertical cylindrical glass envelope is established, and, a computer program is coded to carry out the necessary computations and yield the results in a detailed usable form. The program is versatile and allows for the arbitrary variation of all pertinent parameters. (Author)
Diffusion coefficient calculations for cylindrical cells
Lam-Hime, M.
1983-03-01
An accurate and general diffusion coefficient calculation for cylindrical cells is described using isotropic scattering integral transport theory. This method has been particularly applied to large regular lattices of graphite-moderated reactors with annular coolant channels. The cells are divided into homogeneous zones, and a zone-wise flux expansion is used to formulate a collision probability problem. The reflection of neutrons at the cell boundary is accounted for by the conservation of the neutron momentum. The uncorrected diffusion coefficient Benoist's definition is used, and the described formulation does not neglect any effect. Angular correlation terms, energy coupling non-uniformity and anisotropy of the classical flux are exactly taken into account. Results for gas-graphite typical cells are given showing the importance of these approximations
Study of Cylindrical Honeycomb Solar Collector
Atish Mozumder
2014-01-01
Full Text Available We present the results of our investigation on cylindrical honeycomb solar collector. The honeycomb has been fabricated with transparent cellulose triacetate polymer sheets. Insulation characteristics of the honeycomb were studied by varying the separation between the honeycomb and the absorber plate. The optimal value of the separation was found to be 3.3 mm for which the heat transfer coefficient is 3.06 W m−2 K−1. This supports result of previous similar experiments. Further we test the honeycomb through a field experiment conducted in Delhi (28.6°N, 77°E and found that when the incident angle of the solar radiation is within 20° then the performance of the system with the honeycomb is better than the one without the honeycomb.
Wang, Fei; Gong, Haoran; Chen, Xi; Chen, C. Q.
2016-09-01
Origami structures enrich the field of mechanical metamaterials with the ability to convert morphologically and systematically between two-dimensional (2D) thin sheets and three-dimensional (3D) spatial structures. In this study, an in-plane design method is proposed to approximate curved surfaces of interest with generalized Miura-ori units. Using this method, two combination types of crease lines are unified in one reprogrammable procedure, generating multiple types of cylindrical structures. Structural completeness conditions of the finite-thickness counterparts to the two types are also proposed. As an example of the design method, the kinematics and elastic properties of an origami-based circular cylindrical shell are analysed. The concept of Poisson’s ratio is extended to the cylindrical structures, demonstrating their auxetic property. An analytical model of rigid plates linked by elastic hinges, consistent with numerical simulations, is employed to describe the mechanical response of the structures. Under particular load patterns, the circular shells display novel mechanical behaviour such as snap-through and limiting folding positions. By analysing the geometry and mechanics of the origami structures, we extend the design space of mechanical metamaterials and provide a basis for their practical applications in science and engineering.
Liu, Yang; Kim, Eunju; Han, Jeong In
2016-01-01
During the initial development of wearable computing devices, the conductive fibers of Al thin film on cylindrical PET monofilament were fabricated by thermal evaporation. Their electrical current-voltage characteristics curves were excellent for incorporation into wearable devices such as fiber-based cylindrical capacitors or thin film transistors. Their surfaces were modified by UV exposure and dip coating of acryl or PVP to investigate the surface effect. The conductive fiber with PVP coating showed the best conductivities because the rough surface of the PET substrate transformed into a smooth surface. The conductivities of PET fiber with and without PVP were 6.81 × 103 Ω-1cm-1 and 5.62 × 103 Ω-1cm-1, respectively. In order to understand the deposition process of Al thin film on cylindrical PET, Al thin film on PET fiber was studied using SEM (Scanning Electron Microscope), conductivities and thickness measurements. Hillocks on the surface of conductive PET fibers were observed and investigated by AFM on the surface. Hillocks were formed and grown during Al thermal evaporation because of severe compressive strain and plastic deformation induced by large differences in thermal expansion between PET substrate and Al thin film. From the analysis of hillock size distribution, it turns out that hillocks grew not transversely but longitudinally. [Figure not available: see fulltext.
Savchenko, V.G.
1995-01-01
In this investigation, we will use a cylindrical coordinate system to study the stress state of laminated shells of revolution made of inelastically deforming isotropic materials and elastic materials with linear orthotropy. One of the principal directions of anisotropy coincides with the axis of revolution of the body. The shells will be subjected to nonaxisymmetric loading by body bar K (K Z , K r , K var-phi ) and surface bar t n (t nz , t nr , t nvar-phi ) forces and heating. The level of loading is such that the rheological properties of the materials of the layers are not a factor, although their thermomechanical characteristics depend on temperature. In addition, the loading and heating of the body occur in such a way that simple (or close to simple) deformation processes take place in its isotropic elements. These processes are accompanied by inelastic strains and the formation of unloading regions in which plastic strains having the sign opposite the initial strains develop. It is assumed that the layers of the body are secured to one another without interference and that conditions corresponding to ideal contact prevail at their interfaces
Welding of a metal-polymer laminate
Gower, H.L.
2007-01-01
The purpose of this work is to investigate the weldability of a metal polymer sandwich structure. The welding of the sandwich material proceeds first by welding of the skin layer. The material selected for this research is Steelite, a sandwich structure developed by Corus, with 0.12 mm thick mild
Vascular Dysfunction in Horses with Endocrinopathic Laminitis.
Ruth A Morgan
Full Text Available Endocrinopathic laminitis (EL is a vascular condition of the equine hoof resulting in severe lameness with both welfare and economic implications. EL occurs in association with equine metabolic syndrome and equine Cushing's disease. Vascular dysfunction, most commonly due to endothelial dysfunction, is associated with cardiovascular risk in people with metabolic syndrome and Cushing's syndrome. We tested the hypothesis that horses with EL have vascular, specifically endothelial, dysfunction. Healthy horses (n = 6 and horses with EL (n = 6 destined for euthanasia were recruited. We studied vessels from the hooves (laminar artery, laminar vein and the facial skin (facial skin arteries by small vessel wire myography. The response to vasoconstrictors phenylephrine (10-9-10-5M and 5-hydroxytryptamine (5HT; 10-9-10-5M and the vasodilator acetylcholine (10-9-10-5M was determined. In comparison with healthy controls, acetylcholine-induced relaxation was dramatically reduced in all intact vessels from horses with EL (% relaxation of healthy laminar arteries 323.5 ± 94.1% v EL 90.8 ± 4.4%, P = 0.01, laminar veins 129.4 ± 14.8% v EL 71.2 ± 4.1%, P = 0.005 and facial skin arteries 182.0 ± 40.7% v EL 91.4 ± 4.5%, P = 0.01. In addition, contractile responses to phenylephrine and 5HT were increased in intact laminar veins from horses with EL compared with healthy horses; these differences were endothelium-independent. Sensitivity to phenylephrine was reduced in intact laminar arteries (P = 0.006 and veins (P = 0.009 from horses with EL. Horses with EL exhibit significant vascular dysfunction in laminar vessels and in facial skin arteries. The systemic nature of the abnormalities suggest this dysfunction is associated with the underlying endocrinopathy and not local changes to the hoof.
Free Vibration Study of Anti-Symmetric Angle-Ply Laminated Plates under Clamped Boundary Conditions
Viswanathan, K. K.; Karthik, K.; Sanyasiraju, Y. V. S. S.; Aziz, Z. A.
2016-11-01
Two type of numerical approach namely, Radial Basis Function and Spline approximation, used to analyse the free vibration of anti-symmetric angle-ply laminated plates under clamped boundary conditions. The equations of motion are derived using YNS theory under first order shear deformation. By assuming the solution in separable form, coupled differential equations obtained in term of mid-plane displacement and rotational functions. The coupled differential is then approximated using Spline function and radial basis function to obtain the generalize eigenvalue problem and parametric studies are made to investigate the effect of aspect ratio, length-to-thickness ratio, number of layers, fibre orientation and material properties with respect to the frequency parameter. Some results are compared with the existing literature and other new results are given in tables and graphs.
Mode I Cohesive Law Characterization of Through-Crack Propagation in a Multidirectional Laminate
Bergan, Andrew C.; Davila, Carlos G.; Leone, Frank A.; Awerbuch, Jonathan; Tan, Tein-Min
2014-01-01
A method is proposed and assessed for the experimental characterization of through-the-thickness crack propagation in multidirectional composite laminates with a cohesive law. The fracture toughness and crack opening displacement are measured and used to determine a cohesive law. Two methods of computing fracture toughness are assessed and compared. While previously proposed cohesive characterizations based on the R-curve exhibit size effects, the proposed approach results in a cohesive law that is a material property. The compact tension specimen configuration is used to propagate damage while load and full-field displacements are recorded. These measurements are used to compute the fracture toughness and crack opening displacement from which the cohesive law is characterized. The experimental results show that a steady-state fracture toughness is not reached. However, the proposed method extrapolates to steady-state and is demonstrated capable of predicting the structural behavior of geometrically-scaled specimens.
Suhad D. Salman
2016-07-01
Full Text Available Traditionally, the helmet shell has been used to provide protection against head injuries and fatalities caused by ballistic threats. In this study, because of the high cost of aramid fibres and the necessity for environmentally friendly alternatives, a portion of aramid was replaced with plain woven kenaf fibre, with different arrangements and thicknesses, without jeopardising the requirements demanded by U.S. Army helmet specifications. Furthermore, novel helmets were produced and tested to reduce the dependency on the ballistic resistance components. Their use could lead to helmets that are less costly and more easily available than conventional helmet armour. The hybrid materials subjected to ballistic tests were composed of 19 layers and were fabricated by the hot press technique using different numbers and configurations of plain woven kenaf and aramid layers. In the case of ballistic performance tests, a positive effect was found for the hybridisation of kenaf and aramid laminated composites.
Neutron diffraction stress determination in W-laminates for structural divertor applications
R. Coppola
2015-07-01
Full Text Available Neutron diffraction measurements have been carried out to develop a non-destructive experimental tool for characterizing the crystallographic structure and the internal stress field in W foil laminates for structural divertor applications in future fusion reactors. The model sample selected for this study had been prepared by brazing, at 1085 °C, 13 W foils with 12 Cu foils. A complete strain distribution measurement through the brazed multilayered specimen and determination of the corresponding stresses has been obtained, assuming zero stress in the through-thickness direction. The average stress determined from the technique across the specimen (over both ‘phases’ of W and Cu is close to zero at −17 ± 32 MPa, in accordance with the expectations.
Steel skin - SMC laminate structures for lightweight automotive manufacturing
Quagliato, Luca; Jang, Changsoon; Murugesan, Mohanraj; Kim, Naksoo
2017-09-01
In the present research work an innovative material, made of steel skin and sheet molding compound core, is presented and is aimed to be utilized for the production of automotive body frames. For a precise description of the laminate structure, the material properties of all the components, including the adhesive utilized as an interlayer, have been carried out, along with the simple tension test of the composite material. The result have shown that the proposed laminate structure has a specific yield strength 114% higher than 6061 T6 aluminum, 34% higher than 7075 T6 aluminum, 186% higher than AISI 304 stainless steel (30HRC) and 42% than SK5 high-strength steel (52HRC), showing its reliability and convenience for the realization of automotive components. After calibrating the material properties of the laminate structure, and utilizing as reference the simple tension results of the laminate structure, the derived material properties have been utilized for the simulation of the mechanical behavior of an automotive B-pillar. The results have been compared with those of a standard B-pillar made of steel, showing that the MS-SMC laminate structure manifests load and impact carry capacity comparable with those of high strength steel, while granting, at least, an 11% weight reduction.
Gautam, Girish Dutt; Pandey, Arun Kumar
2018-03-01
Kevlar is the most popular aramid fiber and most commonly used in different technologically advanced industries for various applications. But the precise cutting of Kevlar composite laminates is a difficult task. The conventional cutting methods face various defects such as delamination, burr formation, fiber pullout with poor surface quality and their mechanical performance is greatly affected by these defects. The laser beam machining may be an alternative of the conventional cutting processes due to its non-contact nature, requirement of low specific energy with higher production rate. But this process also faces some problems that may be minimized by operating the machine at optimum parameters levels. This research paper examines the effective utilization of the Nd:YAG laser cutting system on difficult-to-cut Kevlar-29 composite laminates. The objective of the proposed work is to find the optimum process parameters settings for getting the minimum kerf deviations at both sides. The experiments have been conducted on Kevlar-29 composite laminates having thickness 1.25 mm by using Box-Benkhen design with two center points. The experimental data have been used for the optimization by using the proposed methodology. For the optimization, Teaching learning Algorithm based approach has been employed to obtain the minimum kerf deviation at bottom and top sides. A self coded Matlab program has been developed by using the proposed methodology and this program has been used for the optimization. Finally, the confirmation tests have been performed to compare the experimental and optimum results obtained by the proposed methodology. The comparison results show that the machining performance in the laser beam cutting process has been remarkably improved through proposed approach. Finally, the influence of different laser cutting parameters such as lamp current, pulse frequency, pulse width, compressed air pressure and cutting speed on top kerf deviation and bottom kerf
The magnetic properties of the hollow cylindrical ideal remanence magnet
Bjørk, Rasmus
2016-01-01
We consider the magnetic properties of the hollow cylindrical ideal remanence magnet. This magnet is the cylindrical permanent magnet that generates a uniform field in the cylinder bore, using the least amount of magnetic energy to do so. The remanence distribution of this magnet is derived...
Cylindrical and spherical dust-acoustic wave modulations in dusty ...
Abstract. The nonlinear wave modulation of planar and non-planar (cylindrical and spherical) dust-acoustic waves (DAW) propagating in dusty plasmas, in the presence of non-extensive distribu- tions for ions and electrons is investigated. By employing multiple scales technique, a cylindrically and spherically modified ...
Coupled dilaton and electromagnetic field in cylindrically symmetric ...
The dilaton black hole solutions have attracted considerable attention for the ... theory and study the corresponding cylindrically symmetric spacetime, where .... where Йm and Йe are integration constants to be interpreted later as the ..... feature is apparent for the cylindrically symmetric spacetime in the presence of the dila-.
Ingestion of six cylindrical and four button batteries
Nielsen, Simon U; Rasmussen, Morten; Hoegberg, Lotte C G
2010-01-01
We report a suicidal ingestion of six cylindrical and four button batteries, in combination with overdosed prescription medicine and smoking of cannabis.......We report a suicidal ingestion of six cylindrical and four button batteries, in combination with overdosed prescription medicine and smoking of cannabis....
Settling of a cylindrical particle in a stagnant fluid
Sørensen, Henrik; Rosendahl, Lasse; Yin, Chungen
The objective of this work is to collect data and develop models for cylindrical particles which could be used in numerical multiphase flow modeling. Trajectories of cylindrical particles settling in stagnant water are filmed from two directions in order to derive detailed information on their mo...
Analysis of radial vibrations of poroelastic circular cylindrical shells ...
DR OKE
vanished, the considered problem reduces to the problem of radial vibrations of fluid-filled poroelastic circular cylindrical shell. (2). When the .... the volume change of the solid to that of liquid. ..... When the outer fluid density is zero, that is, ρof = 0 then the poroelastic cylindrical shell immersed in an acoustic medium will.
Ocean Sediment Thickness Contours
National Oceanic and Atmospheric Administration, Department of Commerce — Ocean sediment thickness contours in 200 meter intervals for water depths ranging from 0 - 18,000 meters. These contours were derived from a global sediment...
Czubek, J.A.; Woznicka, U.
1997-01-01
A solution of the neutron diffusion equation is given for a three layer cylindrical coaxial geometry. The calculation is performed in two neutron-energy groups which distinguish the thermal and epithermal neutron fluxes in the media irradiated by the fast point neutron source. The aim of the calculation is to define the neutron slowing down and migration lengths which are observed at a given point of the system. Generally, the slowing down and migration lengths are defined for an infinite homogenous medium (irradiated by the point neutron source) as a quotient of the neutron flux moment of the (2n + 2)-order to the moment of the 2n-order. Czubek(1992) introduced in the same manner the apparent neutron slowing down length and the apparent migration length for a given multi-region cylindrical geometry. The solutions in the present paper are applied to the method of semi-empirical calibration of neutron well-logging tools. The three-region cylindrical geometry corresponds to the borehole of radius R 1 surrounded by the intermediate region (e.g. mud cake) of thickness (R 2 -R 1 ) and finally surrounded by the geological formation which spreads from R 2 up to infinity. The cylinders of an infinite length are considered. The paper gives detailed solutions for the 0-th, 2-nd and 4-th neutron moments of the neutron fluxes for each neutron energy group and in each cylindrical layer. A comprehensive list of the solutions for integrals containing Bessel functions or their derivatives, which are absent in common tables of integrals, is also included. (author)
Czubek, J.A.; Woznicka, U. [The H. Niewodniczanski Inst. of Nuclear Physics, Cracow (Poland)
1997-12-31
A solution of the neutron diffusion equation is given for a three layer cylindrical coaxial geometry. The calculation is performed in two neutron-energy groups which distinguish the thermal and epithermal neutron fluxes in the media irradiated by the fast point neutron source. The aim of the calculation is to define the neutron slowing down and migration lengths which are observed at a given point of the system. Generally, the slowing down and migration lengths are defined for an infinite homogenous medium (irradiated by the point neutron source) as a quotient of the neutron flux moment of the (2n{sup +}2)-order to the moment of the 2n-order. Czubek(1992) introduced in the same manner the apparent neutron slowing down length and the apparent migration length for a given multi-region cylindrical geometry. The solutions in the present paper are applied to the method of semi-empirical calibration of neutron well-logging tools. The three-region cylindrical geometry corresponds to the borehole of radius R{sub 1} surrounded by the intermediate region (e.g. mud cake) of thickness (R{sub 2}-R{sub 1}) and finally surrounded by the geological formation which spreads from R{sub 2} up to infinity. The cylinders of an infinite length are considered. The paper gives detailed solutions for the 0-th, 2-nd and 4-th neutron moments of the neutron fluxes for each neutron energy group and in each cylindrical layer. A comprehensive list of the solutions for integrals containing Bessel functions or their derivatives, which are absent in common tables of integrals, is also included. (author) 6 refs, 2 figs
Fast calculation method for computer-generated cylindrical holograms.
Yamaguchi, Takeshi; Fujii, Tomohiko; Yoshikawa, Hiroshi
2008-07-01
Since a general flat hologram has a limited viewable area, we usually cannot see the other side of a reconstructed object. There are some holograms that can solve this problem. A cylindrical hologram is well known to be viewable in 360 deg. Most cylindrical holograms are optical holograms, but there are few reports of computer-generated cylindrical holograms. The lack of computer-generated cylindrical holograms is because the spatial resolution of output devices is not great enough; therefore, we have to make a large hologram or use a small object to fulfill the sampling theorem. In addition, in calculating the large fringe, the calculation amount increases in proportion to the hologram size. Therefore, we propose what we believe to be a new calculation method for fast calculation. Then, we print these fringes with our prototype fringe printer. As a result, we obtain a good reconstructed image from a computer-generated cylindrical hologram.
Wenqiang Wei
2016-05-01
Full Text Available At present, the details of lamina alterations after baculovirus infection remain elusive. In this study, a lamin gene in the Sf9 cell line of Spodoptera frugiperda was cloned. The open reading frame (orf of the Sf9 lamin was 1860 bp and encoded a protein with a molecular weight of 70 kDa. A transfection assay with a red fluorescence protein (rfp-lamin fusion protein indicated that Sf9 lamin was localized in the nuclear rim. Transmission electron microscopy observations indicated that Autographa californica multiple nucleopolyhedrovirus (AcMNPV nucleocapsids may pass through the nuclear envelope. Immunofluorescence assay indicated that the lamina showed a ruffled staining pattern with the formation of invaginations in the Sf9 cells infected with AcMNPV, while it was evenly distributed at the nuclear periphery of mock-infected cells. Western blotting results indicated that the total amount of lamin in the baculovirus-infected Sf9 cells was significantly decreased compared with the mock-infected cells. These results imply that AcMNPV infection induces structural and biochemical rearrangements of lamina of Sf9 cells.
Correlation of laminated MR apperance of articular cartilage with histology
Kim, Dong Joon; Suh, Jin Suck; Jeong, Eun Kee; Shin, Kyu Ho; Yang, Woo Ick
1999-01-01
To determine the correlation of laminae of different signal intensities (SI) of articular cartilage, as seen on magnetic resonance(MR) imaging with histologic layers, using artificially constructed landmarks. For a landmark that can exactly correlate the cartilage specimen with the MR image, five 'V'-shaped markings of different depths were made on the surface of bovine patella. Both T1-weighted (TR/TE : 300/14) and FSE T2-weighted images (TR/TE : 2000/53) were obtained on a 1.5T system with high gradient echo strength (25mT/m) and a voxel size of 78X78X2000μm. Images were obtained with 1) changed frequency-encoding directions on T1-weighted study, and 2) changed readout gradient strength ( X2, X1/2) on T2-weighted sequence. Raw image data were transferred to a workstation and signal intensity profile was generated for each image. 1 : 1 correlation of histologic specimens and MR images was performed. Line profile through the cartilage showed few peaks, suggesting changes in signal intensity profile in the cartilage. On the basis of artificial landmarks, the histologic zone was accurately identified. The histologic tangential and transitional zones correlated with superficial high SI on T1WI, as well as high and low SI on T2WI. On T1WI, the radial zone correlated with a lamina of intermediate SI, and on T2WI, with a lamina for which SI gradually decreased from high to low. Additional well-defined low and intermediate SI bands were noted on bovine T1WI in the lower radial zone. In both T1 and T2 studies, calcified cartilage layers were of low SI. On T1-weighted study, changes in the direction of frequency gradient did not lead to changes in the laminae. The alteration of readout gradient strengths did not result in an inversely proportional difference in the thickness of the laminae. These became more distinct thus ruling out chemical shift and susceptibility artifacts. The laminated appearance of articular cartilage, as seen on spin echo and fast spin-echo MR
Using lamb waves tomonitor moisture absorption thermally fatigues composite laminates
Lee, Jae Sun; Cho, Youn Ho [School of Mechanical Engineering, Pusan National University, Busan (Korea, Republic of)
2016-06-15
Nondestructive evaluation for material health monitoring is important in aerospace industries. Composite laminates are exposed to heat cyclic loading and humid environment depending on flight conditions. Cyclic heat loading and moisture absorption may lead to material degradation such as matrix breaking, debonding, and delamination. In this paper, the moisture absorption ratio was investigated by measuring the Lamb wave velocity. The composite laminates were manufactured and subjected to different thermal aging cycles and moisture absorption. For various conditions of these cycles, not only changes in weight and also ultrasonic wave velocity were measured, and the Lamb wave velocity at various levels of moisture on a carbon-epoxy plate was investigated. Results from the experiment show a linear correlation between moisture absorption ratio and Lamb wave velocity at different thermal fatigue stages. The presented method can be applied as an alternative solution in the online monitoring of composite laminate moisture levels in commercial flights.
Selvakumaran, Lakshmi; Lubineau, Gilles
2014-01-01
Electrical Resistance Tomography (ERT) is a promising health monitoring technique to assess damage in laminated composites. Yet, the missing link between the various complex degradation mechanisms within the laminate and its global change
Process monitoring of glass reinforced polypropylene laminates using fiber Bragg gratings
Mulle, Matthieu; Wafai, Husam; Yudhanto, Arief; Lubineau, Gilles; Yaldiz, R.; Schijve, W.; Verghese, N.
2015-01-01
Hot-press molding of glass-fiber-reinforced polypropylene (GFPP) laminates was monitored using longitudinally and transversely embedded fiber Bragg gratings (FBGs) at different locations in unidirectional laminates. The optical sensors proved
Fabrication technology for a series of cylindrical thin-wall cavity targets
Zheng Yong; Sun Zu Oke; Wang Ming Da; Zhou La; Zhou Zhi Yun
2002-01-01
Cylindrical thin-wall cavity targets have been fabricated to study the behavior of superthermal electrons and their effects on inertial confinement fusion (ICF). Self-supporting cavity targets having adjustable, uniform wall thickness, and low surface roughness were required. This required production of high-quality mandrels, coating them by sputtering or electroplating, developing techniques for measurement of wall thickness and other cavity parameters, improving the uniformity of rotation of the mandrels, and preventing damage to the targets during removal from the mandrels. Details of the fabrication process are presented. Experimental results from the use of these targets are presented. These results, in good agreement with simulations, indicate that the use of thin-wall cavity targets is an effective method for studying superthermal electrons in ICF.
Optimal design of sandwich ribbed flat baffle plates of a circular cylindrical tank
Malinowski, Marek; Magnucki, Krzysztof
2005-01-01
The subject of this paper is a sandwich ribbed flat baffle plate of a circular cylindrical tank. The paper deals with a problem of optimal thickness of this construction with a soft core. The construction is distinguished by a local axisymmetric pre-springing. The mathematical description is based on the theory of shells with analysis of disturbance of the stress membrane state. The sandwich ribbed flat baffle plate divides the tank into two chambers. One of them is loaded by uniform pressure, while the other is empty and unloaded. Dimensions of ribs, faces and the entire baffle plate have been determined with a view to minimize the mass under strength constraints. The effect of optimal thickness of this sandwich plate has been examined by means of the finite element method
Antibubbles and fine cylindrical sheets of air
Beilharz, D.; Guyon, A.; Li, E.Q.; Thoraval, Marie-Jean; Thoroddsen, S.T.
2015-01-01
Drops impacting at low velocities onto a pool surface can stretch out thin hemispherical sheets of air between the drop and the pool. These air sheets can remain intact until they reach submicron thicknesses, at which point they rupture to form a myriad of microbubbles. By impacting a
Feeding practices and potential risk factors for laminitis in dairy cows in Thailand
Pilachai, R.
2013-01-01
Laminitis is considered an important health problem facing the Thai dairy industry. Although the etiology of laminitis is multifactorial, nutrition is considered an important risk factor. Rumen acidosis, lipopolysaccharides (LPS) and histamine may play a role in the development of laminitis in dairy cattle. However, the relevancy of these risk factors in relation to the occurrence of laminitis under practical feeding conditions in Thailand is not clear. In Thailand, dairy rations are generall...
Subclinical laminitis and its association with pO2 and faecal alterations: Isikli, Aydin experience
Ibrahim Akin; Deniz Alic Ural; Mehmet Gultekin; Kerem Ural
2015-01-01
ABSTRACTObjective. The aim of this field trial was to investigate the relationships among subclinical laminitis, hematological, ruminal and faecal alterations. Materials and Methods. To this extent dairy cows presenting subclinical laminitis (n=11) and to those of other healthy cows without laminitis (n=10) were enrolled and assigned into two groups. All animals were receiving the same daily ration formulated to contain 47% cornsilage and 18% hay, mainly. Effects of subclinical laminitis chal...
A transparent, solvent-free laminated top electrode for perovskite solar cells
Makha, Mohammed; Fernandes, Silvia Let?cia; Jenatsch, Sandra; Offermans, Ton; Schleuniger, J?rg; Tisserant, Jean-Nicolas; V?ron, Anna C.; Hany, Roland
2016-01-01
Abstract A simple lamination process of the top electrode for perovskite solar cells is demonstrated. The laminate electrode consists of a transparent and conductive plastic/metal mesh substrate, coated with an adhesive mixture of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate), PEDOT:PSS, and sorbitol. The laminate electrode showed a high degree of transparency of 85%. Best cell performance was achieved for laminate electrodes prepared with a sorbitol concentration of ~30 wt% per mil...
Theoretical models to predict the mechanical behavior of thick composite tubes
Volnei Tita
2012-02-01
Full Text Available This paper shows theoretical models (analytical formulations to predict the mechanical behavior of thick composite tubes and how some parameters can influence this behavior. Thus, firstly, it was developed the analytical formulations for a pressurized tube made of composite material with a single thick ply and only one lamination angle. For this case, the stress distribution and the displacement fields are investigated as function of different lamination angles and reinforcement volume fractions. The results obtained by the theoretical model are physic consistent and coherent with the literature information. After that, the previous formulations are extended in order to predict the mechanical behavior of a thick laminated tube. Both analytical formulations are implemented as a computational tool via Matlab code. The results obtained by the computational tool are compared to the finite element analyses, and the stress distribution is considered coherent. Moreover, the engineering computational tool is used to perform failure analysis, using different types of failure criteria, which identifies the damaged ply and the mode of failure.
The fatigue behavior of composite laminates under various mean stresses
Rotem, A.
1991-01-01
A method is developed for predicting the S-N curve of a composite laminate which is subjected to an arbitrary stress ratio, R (minimum stress/maximum stress). The method is based on the measuring of the S-N behavior of two distinct cases, tension-tension and compression-compression fatigue loadings. Using these parameters, expressions are formulated that estimate the fatigue behavior under any stress ratio loading. Experimental results from the testing of graphite/epoxy laminates, with various structures, are compared with the predictions and show good agreement.
Recent developments of discrete material optimization of laminated composite structures
Lund, Erik; Sørensen, Rene
2015-01-01
This work will give a quick summary of recent developments of the Discrete Material Optimization approach for structural optimization of laminated composite structures. This approach can be seen as a multi-material topology optimization approach for selecting the best ply material and number...... of plies in a laminated composite structure. The conceptual combinatorial design problem is relaxed to a continuous problem such that well-established gradient based optimization techniques can be applied, and the optimization problem is solved on basis of interpolation schemes with penalization...
Multi-material topology design of laminates with strength criteria
Lund, Erik
2012-01-01
The objective of this paper is to present a novel approach for multi-material topology optimization of laminated composite structures where strength constraints are taken into account together with other global structural performance measures. The topology design problem considered contains very...... many design variables, and when strength criteria are included in the problem, a very large number of criteria functions must be considered in the optimization problem to be solved. Thus, block aggregation methods are introduced, such that global strength measures are obtained. These formulations...... are illustrated for multi-material laminated design problems where the maximum failure index is minimized while compliance and mass constraints are taken into account....
Criterion of damage beginning: experimental identification for laminate composite
Thiebaud, F.; Perreux, D.; Varchon, D.; Lebras, J.
1996-01-01
The aim of this study is to propose a criterion of damage beginning for laminate composite. The materials is a glass-epoxy laminate [+55 deg.,-55 deg.[ n performed by winding filament process. First of all a description of the damage is performed and allows to define a damage variable. Thanks to the potential of free energy, an associated variable is defined. The damage criterion is written by using this last one. The parameter of the criterion is identified using mechanical and acoustical methods. The result is compared and exhibit a good agreement. (authors). 13 refs., 5 figs
Converging cylindrical shocks in ideal magnetohydrodynamics
Pullin, D. I.; Mostert, W.; Wheatley, V.; Samtaney, R.
2014-01-01
We consider a cylindrically symmetrical shock converging onto an axis within the framework of ideal, compressible-gas non-dissipative magnetohydrodynamics (MHD). In cylindrical polar co-ordinates we restrict attention to either constant axial magnetic field or to the azimuthal but singular magnetic field produced by a line current on the axis. Under the constraint of zero normal magnetic field and zero tangential fluid speed at the shock, a set of restricted shock-jump conditions are obtained as functions of the shock Mach number, defined as the ratio of the local shock speed to the unique magnetohydrodynamic wave speed ahead of the shock, and also of a parameter measuring the local strength of the magnetic field. For the line current case, two approaches are explored and the results compared in detail. The first is geometrical shock-dynamics where the restricted shock-jump conditions are applied directly to the equation on the characteristic entering the shock from behind. This gives an ordinary-differential equation for the shock Mach number as a function of radius which is integrated numerically to provide profiles of the shock implosion. Also, analytic, asymptotic results are obtained for the shock trajectory at small radius. The second approach is direct numerical solution of the radially symmetric MHD equations using a shock-capturing method. For the axial magnetic field case the shock implosion is of the Guderley power-law type with exponent that is not affected by the presence of a finite magnetic field. For the axial current case, however, the presence of a tangential magnetic field ahead of the shock with strength inversely proportional to radius introduces a length scale R=√(μ 0 /p 0 ) I/(2 π) where I is the current, μ 0 is the permeability, and p 0 is the pressure ahead of the shock. For shocks initiated at r ≫ R, shock convergence is first accompanied by shock strengthening as for the strictly gas-dynamic implosion. The diverging magnetic field
Converging cylindrical shocks in ideal magnetohydrodynamics
Pullin, D. I.
2014-09-01
We consider a cylindrically symmetrical shock converging onto an axis within the framework of ideal, compressible-gas non-dissipative magnetohydrodynamics (MHD). In cylindrical polar co-ordinates we restrict attention to either constant axial magnetic field or to the azimuthal but singular magnetic field produced by a line current on the axis. Under the constraint of zero normal magnetic field and zero tangential fluid speed at the shock, a set of restricted shock-jump conditions are obtained as functions of the shock Mach number, defined as the ratio of the local shock speed to the unique magnetohydrodynamic wave speed ahead of the shock, and also of a parameter measuring the local strength of the magnetic field. For the line current case, two approaches are explored and the results compared in detail. The first is geometrical shock-dynamics where the restricted shock-jump conditions are applied directly to the equation on the characteristic entering the shock from behind. This gives an ordinary-differential equation for the shock Mach number as a function of radius which is integrated numerically to provide profiles of the shock implosion. Also, analytic, asymptotic results are obtained for the shock trajectory at small radius. The second approach is direct numerical solution of the radially symmetric MHD equations using a shock-capturing method. For the axial magnetic field case the shock implosion is of the Guderley power-law type with exponent that is not affected by the presence of a finite magnetic field. For the axial current case, however, the presence of a tangential magnetic field ahead of the shock with strength inversely proportional to radius introduces a length scale R = √μ0/p0 I/(2π) where I is the current, μ0 is the permeability, and p0 is the pressure ahead of the shock. For shocks initiated at r ≫ R, shock convergence is first accompanied by shock strengthening as for the strictly gas-dynamic implosion. The diverging magnetic field then
Converging cylindrical shocks in ideal magnetohydrodynamics
Pullin, D. I.; Mostert, W.; Wheatley, V.; Samtaney, Ravi
2014-01-01
We consider a cylindrically symmetrical shock converging onto an axis within the framework of ideal, compressible-gas non-dissipative magnetohydrodynamics (MHD). In cylindrical polar co-ordinates we restrict attention to either constant axial magnetic field or to the azimuthal but singular magnetic field produced by a line current on the axis. Under the constraint of zero normal magnetic field and zero tangential fluid speed at the shock, a set of restricted shock-jump conditions are obtained as functions of the shock Mach number, defined as the ratio of the local shock speed to the unique magnetohydrodynamic wave speed ahead of the shock, and also of a parameter measuring the local strength of the magnetic field. For the line current case, two approaches are explored and the results compared in detail. The first is geometrical shock-dynamics where the restricted shock-jump conditions are applied directly to the equation on the characteristic entering the shock from behind. This gives an ordinary-differential equation for the shock Mach number as a function of radius which is integrated numerically to provide profiles of the shock implosion. Also, analytic, asymptotic results are obtained for the shock trajectory at small radius. The second approach is direct numerical solution of the radially symmetric MHD equations using a shock-capturing method. For the axial magnetic field case the shock implosion is of the Guderley power-law type with exponent that is not affected by the presence of a finite magnetic field. For the axial current case, however, the presence of a tangential magnetic field ahead of the shock with strength inversely proportional to radius introduces a length scale R = √μ0/p0 I/(2π) where I is the current, μ0 is the permeability, and p0 is the pressure ahead of the shock. For shocks initiated at r ≫ R, shock convergence is first accompanied by shock strengthening as for the strictly gas-dynamic implosion. The diverging magnetic field then
Converging cylindrical shocks in ideal magnetohydrodynamics
Pullin, D. I. [Graduate Aerospace Laboratories, California Institute of Technology, Pasadena, California 91125 (United States); Mostert, W.; Wheatley, V. [School of Mechanical and Mining Engineering, University of Queensland, Queensland 4072 (Australia); Samtaney, R. [Mechanical Engineering, Physical Sciences and Engineering Division, King Abdullah University of Science and Technology, Thuwal (Saudi Arabia)
2014-09-15
We consider a cylindrically symmetrical shock converging onto an axis within the framework of ideal, compressible-gas non-dissipative magnetohydrodynamics (MHD). In cylindrical polar co-ordinates we restrict attention to either constant axial magnetic field or to the azimuthal but singular magnetic field produced by a line current on the axis. Under the constraint of zero normal magnetic field and zero tangential fluid speed at the shock, a set of restricted shock-jump conditions are obtained as functions of the shock Mach number, defined as the ratio of the local shock speed to the unique magnetohydrodynamic wave speed ahead of the shock, and also of a parameter measuring the local strength of the magnetic field. For the line current case, two approaches are explored and the results compared in detail. The first is geometrical shock-dynamics where the restricted shock-jump conditions are applied directly to the equation on the characteristic entering the shock from behind. This gives an ordinary-differential equation for the shock Mach number as a function of radius which is integrated numerically to provide profiles of the shock implosion. Also, analytic, asymptotic results are obtained for the shock trajectory at small radius. The second approach is direct numerical solution of the radially symmetric MHD equations using a shock-capturing method. For the axial magnetic field case the shock implosion is of the Guderley power-law type with exponent that is not affected by the presence of a finite magnetic field. For the axial current case, however, the presence of a tangential magnetic field ahead of the shock with strength inversely proportional to radius introduces a length scale R=√(μ{sub 0}/p{sub 0}) I/(2 π) where I is the current, μ{sub 0} is the permeability, and p{sub 0} is the pressure ahead of the shock. For shocks initiated at r ≫ R, shock convergence is first accompanied by shock strengthening as for the strictly gas-dynamic implosion. The
Mutzl, J.
1978-01-01
This burst protection device controls forces to be expected in an accident by resolving them into axial (vertical) and radial (horizontal) components, which are taken by a large number of elements stressed in tension. The steam raising unit is surrounded by a containment, but remains easily accessible. The containment consists of a steel jacket, lid and floor. Several cylindrical sections above one another form the steel jacket, which surrounds the steam raising unit with an intermediate insulating layer of concrete. The insulating concrete cylinder is of several times the thickness of the steel jacket, and also consists of cylindrical sections. An outer supporting ring for the lid and floor of the containment have outside diameters which project beyond the jacket. Prestressed circumferential vertical tension ropes between the supporting ring and floor take any additional tensional forces. The lid is domed with downward curvature towards the upper boiler dome. Internal bursting forces produce compressive stresses in the lid, which thus pass along its outside diameter into the surrounding ring. The lid, which is devided along one diameter, makes dismantling and access to the boiler easy even with a central steam pipe going upwards. The floor of the burst protection is also the floor of the steam raising unit. It is of several times the thickness of the tube floor, which, with its spacing above the floor forms the usual inlet and outlet space for the reactor cooling water. The main coolant pump installed there is driven by an external motor through a floor penetration. (HP) [de
Peculiarities of carrying capacity evaluations of cylindrical CFST columns with new type casing
Sinkovskaya Olena
2017-01-01
Full Text Available This paper deals with a cylindrical steel-concrete load-bearing unit. The feature of the unit is a steel mesh casing that is made from the expanded metal mesh. The optimal parameters of the suggested footing are determined taking into account anisotropy, i. e. different strength and rigidity in different directions that coincide and do not coincide with the direction of reinforcement. The optimal cell angle, when a casing deformation brings about maximum compression of a concrete core, is determined. Details for theoretical calculation of the bearing capacity of a cylindrical steel-concrete load-bearing unit are provided taking into consideration a complex three-dimensional structure of the suggested mesh casing. The validity of the calculations is confirmed by comparison them with the results of the Lira software package. The results of the calculations are provided in the form of the table showing the dependence of the adduced thickness of the plate on the longitudinal movement of the strip of the steel mesh casing. The dependencies to determine the adduced thickness of the mesh casing using the graphical method are provided for all the existing types of the mesh using concrete wedges or excluding them.
Polyelectrolyte layer-by-layer deposition in cylindrical nanopores.
Lazzara, Thomas D; Lau, K H Aaron; Abou-Kandil, Ahmed I; Caminade, Anne-Marie; Majoral, Jean-Pierre; Knoll, Wolfgang
2010-07-27
Layer-by-layer (LbL) deposition of polyelectrolytes within nanopores in terms of the pore size and the ionic strength was experimentally studied. Anodic aluminum oxide (AAO) membranes, which have aligned, cylindrical, nonintersecting pores, were used as a model nanoporous system. Furthermore, the AAO membranes were also employed as planar optical waveguides to enable in situ monitoring of the LbL process within the nanopores by optical waveguide spectroscopy (OWS). Structurally well-defined N,N-disubstituted hydrazine phosphorus-containing dendrimers of the fourth generation, with peripherally charged groups and diameters of approximately 7 nm, were used as the model polyelectrolytes. The pore diameter of the AAO was varied between 30-116 nm and the ionic strength was varied over 3 orders of magnitude. The dependence of the deposited layer thickness on ionic strength within the nanopores is found to be significantly stronger than LbL deposition on a planar surface. Furthermore, deposition within the nanopores can become inhibited even if the pore diameter is much larger than the diameter of the G4-polyelectrolyte, or if the screening length is insignificant relative to the dendrimer diameter at high ionic strengths. Our results will aid in the template preparation of polyelectrolyte multilayer nanotubes, and our experimental approach may be useful for investigating theories regarding the partitioning of nano-objects within nanopores where electrostatic interactions are dominant. Furthermore, we show that the enhanced ionic strength dependence of polyelectrolyte transport within the nanopores can be used to selectively deposit a LbL multilayer atop a nanoporous substrate.
Feeding practices and potential risk factors for laminitis in dairy cows in Thailand
Pilachai, R.
2013-01-01
Laminitis is considered an important health problem facing the Thai dairy industry. Although the etiology of laminitis is multifactorial, nutrition is considered an important risk factor. Rumen acidosis, lipopolysaccharides (LPS) and histamine may play a role in the development of laminitis in dairy
Schatten, G.; Schatten, H.; Simerly, C.; Maul, G. G.; Chaly, N.
1985-01-01
Nuclear structural changes during fertilization and embryogenesis in mice and sea urchins are traced using four antibodies. The oocytes from virgin female mice, morulae and blastocytes from mated females, and gametes from the sea urchin Lytechnius variegatis are studied using mouse monoclonal antibodies to nuclear lamin A/C, monoclonal antibody to P1, human autoimmune antibodies to lamin A/C, and to lamin B. The mouse fertilization data reveal no lamins on the oocyte; however, lamins are present on the pronuclei, and chromosomes are found on the oocytes and pronuclei. It is detected that on the sea urchin sperm the lamins are reduced to acrosomal and centriolar fossae and peripheral antigens are around the sperm nucleus. The mouse sperm bind lamin antibodies regionally and do not contain antigens. Lamins and antigens are observed on both pronuclei and chromosomes during sea urchin fertilization. Mouse embryogenesis reveals that lamin A/C is not recognized at morula and blastocyst stages; however, lamin B stains are retained. In sea urchin embryogenesis lamin recognition is lost at the blastrula, gastrula, and plutei stages. It is noted that nuclear lamins lost during spermatogenesis are restored at fertilization and peripheral antigens are associated with the surface of chromosomes during meiosis and mitosis and with the periphery of the pronuclei and nuclei during interphase.
2012-10-05
... INTERNATIONAL TRADE COMMISSION [Inv. No. 337-TA-659] Certain Prepregs, Laminates, and Finished..., and the sale within the United States after importation of certain prepregs, laminates, and finished... for sale, and selling for importation into the United States prepregs and laminates that are the...
Abnormal A-type lamin organization in a human lung carcinoma cell line
Machiels, BM; Broers, JL; Raymond, Y; de Leij, Louis; Kuijpers, HJH; Caberg, NEH; Ramaekers, Frans C. S.
We have studied the expression of lamins A and C (A-type lamins) in a lung carcinoma cell line using type-specific monoclonal antibodies, Using immunofluorescence and immunoblotting studies it was noted that several irregularities in lamin expression exist in the cell line GLC-A1, derived from an
Hasselberg, Nina E; Edvardsen, Thor; Petri, Helle
2014-01-01
Mutations in the Lamin A/C gene may cause atrioventricular block, supraventricular arrhythmias, ventricular arrhythmias (VA), and dilated cardiomyopathy. We aimed to explore the predictors and the mechanisms of VA in Lamin A/C mutation-positive subjects.METHODS AND RESULTS: We included 41 Lamin A/C...
On the plastic behaviour of multi directional epoxy-bolted CFRP laminates
Jensen, Aage; Poulsen, Ervin
2004-01-01
The second generation of CFRP laminate has recently been developed. It is a multi directional CFRP laminate, i.e. a laminate with carbon fibres having several directions other than the first generation. The paper describes the laboratory tests carried out in order to develop anchorage devices for...
Arbitrarily elliptical-cylindrical invisible cloaking
Jiang Weixiang; Cui Tiejun; Yu Guanxia; Lin Xianqi; Cheng Qiang; Chin, J Y
2008-01-01
Based on the idea of coordinate transformation (Pendry, Schurig and Smith 2006 Science 312 1780), arbitrarily elliptical-cylindrical cloaks are proposed and designed. The elliptical cloak, which is composed of inhomogeneous anisotropic metamaterials in an elliptical-shell region, will deflect incoming electromagnetic (EM) waves and guide them to propagate around the inner elliptical region. Such EM waves will return to their original propagation directions without distorting the waves outside the elliptical cloak. General formulations of the inhomogeneous and anisotropic permittivity and permeability tensors are derived for arbitrarily elliptical axis ratio k, which can also be used for the circular cloak when k = 1. Hence the elliptical cloaks can make a large range of objects invisible, from round objects (when k approaches 1) to long and thin objects (when k is either very large or very small). We also show that the material parameters in elliptical cloaking are singular at only two points, instead of on the whole inner circle for circular cloaking, which are much easier to be realized in actual applications. Full-wave simulations are given to validate the arbitrarily elliptical cloaking
Electrical tensor Green functions for cylindrical waveguides
Prijmenko, S.D.; Papkovich, V.G.; Khizhnyak, N.A.
1988-01-01
Formation of electrical tensor Green functions for cylindrical waveguides is considered. Behaviour of these functions in the source region is studied. Cases of electrical tensor Green functions for vector potential G E (r-vector, r'-vector) and electric field G e (r-vector, r'-vector) are analysed. When forming G E (r-vector, r'-vector), its dependence on lateral coordinates is taken into account by means of two-dimensional fundamental vector Hansen functions, several methods are used to take into account the dependence on transverse coordinate. When forming G e (r-vector, r'-vector) we use the fact that G E (r-vector, r'-vector) and G e (r-vector, r'-vector) are the generalized functions. It is shown that G e (r-vector, r'-vector) behaviour in the source region is defined by a singular term, which properties are described by the delta-function. Two variants of solving the problem of defining singular and regular sides of tensor function G E (r-vector, r'-vector) are presented. 23 refs
Cylindrical Hall Thrusters with Permanent Magnets
Raitses, Yevgeny; Merino, Enrique; Fisch, Nathaniel J.
2010-01-01
The use of permanent magnets instead of electromagnet coils for low power Hall thrusters can offer a significant reduction of both the total electric power consumption and the thruster mass. Two permanent magnet versions of the miniaturized cylindrical Hall thruster (CHT) of different overall dimensions were operated in the power range of 50W-300 W. The discharge and plasma plume measurements revealed that the CHT thrusters with permanent magnets and electromagnet coils operate rather differently. In particular, the angular ion current density distribution from the permanent magnet thrusters has an unusual halo shape, with a majority of high energy ions flowing at large angles with respect to the thruster centerline. Differences in the magnetic field topology outside the thruster channel and in the vicinity of the channel exit are likely responsible for the differences in the plume characteristics measured for the CHTs with electromagnets and permanent magnets. It is shown that the presence of the reversing-direction or cusp-type magnetic field configuration inside the thruster channel without a strong axial magnetic field outside the thruster channel does not lead to the halo plasma plume from the CHT.
Electron emitter pulsed-type cylindrical IEC
Miley, G.H.; Gu, Y.; Stubbers, R.; Zich, R.; Anderl, R.; Hartwell, J.
1997-01-01
A cylindrical version of the single grid Inertial Electrostatic Confinement (IEC) device (termed the C-device) has been developed for use as a 2.5-MeV D-D fusion neutron source for neutron activation analysis. The C-device employs a hollow-tube type cathode with similar anodes backed up by ''reflector'' dishes. The resulting discharge differs from a conventional hollow cathode discharge, by creating an explicit ion beam which is ''pinched'' in the cathode region. Resulting fusion reactions generate ∼10 6 neutron/s. A pulsed version is under development for applications requiring higher fluxes. Several pulsing techniques are under study, including an electron emitter (e-emitter) assisted discharge in a thorated tungsten wire emitter located behind a slotted area in the reflector dishes. Pulsing is initiated after establishing a low power steady-state discharge by pulsing the e-emitter current using a capacitor switch type circuit. The resulting electron jet, coupled with the discharge by the biased slot array, creates a strong pulse in the pinched ion beam. The pulse length/repetition rate are controlled by the e-emitter pulse circuit. Typical parameters in present studies are ∼30micros, 10Hz and 1-amp ion current. Corresponding neutron measurements are an In-foil type activation counter for time averaged rates. Results for a wide variety of operating conditions are presented
Parametric Investigation of Miniaturized Cylindrical and Annular Hall Thrusters
Smirnov, A.; Raitses, Y.; Fisch, N.J.
2002-01-01
Conventional annular Hall thrusters become inefficient when scaled to low power. An alternative approach, a 2.6-cm miniaturized cylindrical Hall thruster with a cusp-type magnetic field distribution, was developed and studied. Its performance was compared to that of a conventional annular thruster of the same dimensions. The cylindrical thruster exhibits discharge characteristics similar to those of the annular thruster, but it has a much higher propellant ionization efficiency. Significantly, a large fraction of multi-charged xenon ions might be present in the outgoing ion flux generated by the cylindrical thruster. The operation of the cylindrical thruster is quieter than that of the annular thruster. The characteristic peak in the discharge current fluctuation spectrum at 50-60 kHz appears to be due to ionization instabilities. In the power range 50-300 W, the cylindrical and annular thrusters have comparable efficiencies (15-32%) and thrusts (2.5-12 mN). For the annular configuration, a voltage less than 200 V was not sufficient to sustain the discharge at low propellant flow rates. The cylindrical thruster can operate at voltages lower than 200 V, which suggests that a cylindrical thruster can be designed to operate at even smaller power
Monitoring production target thickness
Oothoudt, M.A.
1993-01-01
Pion and muon production targets at the Clinton P. Anderson Meson Physics Facility consist of rotating graphite wheels. The previous target thickness monitoring Procedure scanned the target across a reduced intensity beam to determine beam center. The fractional loss in current across the centered target gave a measure of target thickness. This procedure, however, required interruption of beam delivery to experiments and frequently indicated a different fractional loss than at normal beam currents. The new monitoring Procedure compares integrated ups and downs toroid current monitor readings. The current monitors are read once per minute and the integral of readings are logged once per eight-hour shift. Changes in the upstream to downstream fractional difference provide a nonintrusive continuous measurement of target thickness under nominal operational conditions. Target scans are now done only when new targets are installed or when unexplained changes in the current monitor data are observed
Wang Junping; Shah, Ami; Yu Xiaojun
2011-01-01
We have developed a 3D nanofibrous spiral scaffold for bone tissue engineering which has shown enhanced cell attachment, proliferation and differentiation compared to traditional cylindrical scaffolds due to the spiral structures and the nanofiber incorporation. Some important parameters of these spiral scaffolds including gap distance, wall thickness and especially fiber thickness are crucial to the performance of the spiral structured scaffolds. In this study, we investigated the fiber thickness, gap distance and wall thickness of the spiral structure on the behavior of osteoblast cells. The human osteoblast cells are seeded on spiral structured scaffolds with various fiber thickness, gap distance and wall thickness and cell attachment, proliferation, differentiation and mineralized matrix deposition on the scaffolds are evaluated. It was found that increasing the thickness of nanofiber layer not only limited the cell infiltration into the scaffolds, but also restrained the osteoblastic cell phenotype development. Moreover, the geometric effect studies indicated that scaffolds with the thinner wall and gap distance 0.2 mm show the best bioactivity for osteoblasts.
Lal Achchhe
2017-09-01
Full Text Available This paper presents the free vibration response of piezo laminated composite geometrically nonlinear conical shell panel subjected to a thermo-electrical loading. The temperature field is assumed to be a uniform distribution over the shell surface and through the shell thickness and the electric field is assumed to be the transverse component E2 only. The material properties are assumed to be independent of the temperature and the electric field. The basic formulation is based on higher order shear deformation plate theory (HSDT with von-Karman nonlinearity. A C0 nonlinear finite element method based on direct iterative approach is outlined and applied to solve nonlinear generalized eigenvalue problem. Parametric studies are carried out to examine the effect of amplitude ratios, stacking sequences, cone angles, piezoelectric layers, applied voltages, circumferential length to thickness ratios, change in temperatures and support boundary conditions on the nonlinear natural frequency of laminated conical shell panels. The present outlined approach has been validated with those available results in the literature.
Cylindrical solitons in shallow water of variable depth
Carbonaro, P.; Floris, R.; Pantano, P.
1983-01-01
The propagation and the interaction of cylindrical solitons in shallow water of variable depth are studied. Starting from the cylindrically symmetric version of the equations describing long waves in a beach, a Korteweg-de Vries equation is derived. Since no exact analytical solution has been found to date for this equation, some remarkable cases in which the equation takes up a tractable form are analyzed. Finally the intercation between cylindrical imploding and expanding waves is considered and the phase shifts caused by the head-on collision are given
Vibrational analysis of submerged cylindrical shells based on elastic foundations
Shah, A.G.; Naeem, M.N.
2014-01-01
In this study a vibration analysis was performed of an isotropic cylindrical shell submerged in fluid, resting on Winkler and Pasternak elastic foundations for simply supported boundary condition. Love's thin shell theory was exploited for strain- and curvature- displacement relationship. Shell problem was solved by using wave propagation approach. Influence of fluid and Winkler as well as Pasternak elastic foundations were studied on the natural frequencies of submerged isotropic cylindrical shells. Results were validated by comparing with the existing results in literature. Vibration, Submerged cylindrical shell, Love's thin shell theory, Wave propagation method, Winkler and Pasternak foundations. (author)
G. H. Rahimi
2014-01-01
Full Text Available A three-dimensional elasticity theory by means of a state-space based differential quadrature method is presented for free vibration analysis of fiber metal laminate annular plate. The kinds of composite material and metal layers are considered to be S2-glass and aluminum, respectively. A semianalytical approach which uses state-space in the thickness and differential quadrature in the radial direction is implemented for evaluating the nondimensional natural frequencies of the annular plates. The influences of changes in boundary condition, plate thickness, and lay-up direction on the natural frequencies are studied. A comparison is also made with the numerical results reported by ABAQUS software which shows an excellent agreement.
Process-induced viscoelastic stress in composite laminates
Stango, R.J.
1985-01-01
In recent years, considerable interest has developed in evaluating the stress response of composite laminates which is associated with cooling the material system from the cure temperature to room temperature. This research examines the fundamental nature of time-dependent residual-thermal stresses in composite laminates which are caused by the extreme temperature reduction encountered during the fabrication process. Viscoelastic stress in finite-width, symmetric composite laminates is examined on the basis of a formulation that employs an incremental hereditary integral approach in conjunction with a quasi-three dimensional finite element analysis. A consistent methodology is developed and employed for the characterization of lamina material properties. Special attention is given to the time-dependent stress response at ply-interface locations near the free-edge. In addition, the influence of cooling path on stress history is examined. Recently published material property data for graphite-epoxy lamina is employed in the analysis. Results of the investigation generally indicate that nominal differences between the thermoelastic and viscoelastic solutions are obtained. Slight changes of the final stress state are observed to result when different cooling paths are selected for the temperature history. The methodology employed is demonstrated to result in an accurate, efficient, and consistent approach for the viscoelastic analysis of advanced composite laminates
Laminated structure in internally oxidized Ru-Ta coatings
Chen, Yung-I, E-mail: yichen@mail.ntou.edu.tw
2012-12-01
During the development of refractory alloy coatings for protective purposes at high temperature under oxygen-containing atmospheres, previous studies noted and examined the internal oxidation phenomenon for Mo-Ru and Ru-Ta coatings. The internally oxidized zone shows a laminated structure, consisting of alternating oxygen-rich and deficient layers stacked with a general orientation. Previous studies proposed a forming mechanism. To investigate in detail, Ru-Ta coatings were prepared with various rotating speeds of a substrate-holder. The coatings were annealed at 600 Degree-Sign C in an atmosphere continuously purged with 1% O{sub 2}-99% Ar mixed gas for 30 min. Transmission electron microscopy was used to examine the laminated-layer periods. Auger electron spectroscopy depth profiles certified the periodical variation of the related constituents. X-ray photoelectron spectroscopy proved the valence variation of Ta in the near surface, accompanied by the introduction of oxygen ions. The inward diffusion of oxygen was dominated by lattice diffusion. - Highlights: Black-Right-Pointing-Pointer Laminated Ru-Ta coatings consisted of a cyclical gradient concentration. Black-Right-Pointing-Pointer The as-deposited coatings showed a laminated structure with a period of 4-34 nm. Black-Right-Pointing-Pointer Internal oxidation of Ru-Ta coatings executed after annealing in 1% O{sub 2}-Ar atmosphere. Black-Right-Pointing-Pointer Oxygen inward diffusion was dominated by lattice diffusion.
Design of Multiple Bolted Connections for Laminated Veneer Lumber
Borjen Yeh; Douglas Rammer; Jeff Linville
2014-01-01
The design of multiple bolted connections in accordance with Appendix E of the National Design Specification for Wood Construction (NDS) has incorporated provisions for evaluating localized member failure modes of row and group tear-out when the connections are closely spaced. Originally based on structural glued laminated timber (glulam) members made with all L1...
Bending analysis of laminated composite plates using finite element ...
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theory to analyze the laminated composite plates. They concluded that ...... Aeronautics and Astronautics”, Inc.1801, Chapter 8, pp. 240. Baltacıoğlu A.K .... He is working as Assistant Professor in the Department of Mechanical. Engineering in ...
Characterisation of fibre metal laminates under thermomechanical loadings
Hagenbeek, M.
2005-01-01
Fibre metal laminates, such as Arall or Glare, can offer improved properties compared to monolithic materials. Glare for example shows improved fatigue, residual strength, burn-through, impact and corrosion properties with respect to aluminium 2024, together with a considerable weight reduction and
Chapter 4: Lateral design of cross-laminated timber buildings
John W. van de Lindt; Douglas Rammer; Marjan Popovski; Phil Line; Shiling Pei; Steven E. Pryor
2013-01-01
Cross-laminated timber (CLT) is an innovative wood product that was developed approximately two decades ago in Europe and has since been gaining in popularity. Based on the experience of European researchers and designers, it is believed that CLT can provide the U.S. market the opportunity to build mid- and high-rise wood buildings. This Chapter presents a summary of...
Thermoviscoelastic characterization and prediction of Kevlar/epoxy composite laminates
Gramoll, K. C.; Dillard, D. A.; Brinson, H. F.
1990-01-01
The thermoviscoelastic characterization of Kevlar 49/Fiberite 7714A epoxy composite lamina and the development of a numerical procedure to predict the viscoelastic response of any general laminate constructed from the same material were studied. The four orthotropic material properties, S sub 11, S sub 12, S sub 22, and S sub 66, were characterized by 20 minute static creep tests on unidirectional (0) sub 8, (10) sub 8, and (90) sub 16 lamina specimens. The Time-Temperature Superposition-Principle (TTSP) was used successfully to accelerate the characterization process. A nonlinear constitutive model was developed to describe the stress dependent viscoelastic response for each of the material properties. A numerical procedure to predict long term laminate properties from lamina properties (obtained experimentally) was developed. Numerical instabilities and time constraints associated with viscoelastic numerical techniques were discussed and solved. The numerical procedure was incorporated into a user friendly microcomputer program called Viscoelastic Composite Analysis Program (VCAP), which is available for IBM PC type computers. The program was designed for ease of use. The final phase involved testing actual laminates constructed from the characterized material, Kevlar/epoxy, at various temperatures and load level for 4 to 5 weeks. These results were compared with the VCAP program predictions to verify the testing procedure and to check the numerical procedure used in the program. The actual tests and predictions agreed for all test cases which included 1, 2, 3, and 4 fiber direction laminates.
Damage and Failure of Non-Conventional Composite Laminates
Lopes, C.S.
2009-01-01
For a long time, the application of composite materials was restricted to military aircraft and secondary structures of commercial aircraft. Furthermore, the design possibilities offered by composite laminates were narrowed to quasi-isotropic configurations due to their closer behaviour with
Photodegradation in ballistic laminates: Spectroscopy and lifetime extension
Renschler, C.L.; Stallard, B.R.; White, C.A.; Garcia, M.J.; Morse, H.E. [Sandia National Labs., Albuquerque, NM (United States). Properties of Organic Materials Dept.
1996-06-01
Several years ago, the Materials and Process Sciences Center (Org. 1800) was asked by Dept. 9613 to study the materials aging issues which had led to the loss of ballistic protection by Armored Tractor (AT) windshields and windows. The authors speculated that this loss of impact strength was due to photodegradation of the polycarbonate (PC) inboard ply. They developed a spectroscopic method to identify changes in the outboard surface of the PC, and showed that the changes in the surface which occurred upon natural aging in the field could be reproduced by exposing the laminates to a simulated solar flux. Based on these results, they recommended changes in the adhesive interlayers to filter out the ultraviolet (UV) light causing the aging problem. Working with the laminate vendor, PPG, they re-designed the laminates to implement these changes and block essentially all UV light from the inboard ply. The most recent phase of this work involved accelerated solar aging of laminates made with the new design to verify that photoaging effects have been blocked by the new materials. They report here the results of that study, and recommended follow-on work.
Computational Fatigue Life Analysis of Carbon Fiber Laminate
Shastry, Shrimukhi G.; Chandrashekara, C. V., Dr.
2018-02-01
In the present scenario, many traditional materials are being replaced by composite materials for its light weight and high strength properties. Industries like automotive industry, aerospace industry etc., are some of the examples which uses composite materials for most of its components. Replacing of components which are subjected to static load or impact load are less challenging compared to components which are subjected to dynamic loading. Replacing the components made up of composite materials demands many stages of parametric study. One such parametric study is the fatigue analysis of composite material. This paper focuses on the fatigue life analysis of the composite material by using computational techniques. A composite plate is considered for the study which has a hole at the center. The analysis is carried on (0°/90°/90°/90°/90°)s laminate sequence and (45°/-45°)2s laminate sequence by using a computer script. The life cycles for both the lay-up sequence are compared with each other. It is observed that, for the same material and geometry of the component, cross ply laminates show better fatigue life than that of angled ply laminates.
Self-extinguishment of cross-laminated timber
Crielaard, R.; van de Kuilen, J.W.G.; Terwel, K.C.; Ravenshorst, G.J.P.; Steenbakkers, P.; Breunesse, A.
2016-01-01
Cross-laminated timber, or CLT, is receiving attention for its potential use in tall buildings. As a combustible material, one of the challenges for the construction of these buildings is the fire risk that results from its use in the structure. Unprotected CLT can burn along with the fuel load
Dual Teichmüller and lamination spaces
Fock, Vladimir V.; Goncharov, Alexander B.
2007-01-01
We survey explicit coordinate descriptions for two versions of Teichmüller and lamination spaces for open surfaces, and extend them to the more general set-up of surfaces with distinguished collections of points on the boundary. Main features, such as mapping class group action, Poisson and sympl...
Buckling analysis for anisotropic laminated plates under combined inplane loads
Viswanathan, A. V.; Tamekuni, M.; Baker, L. L.
1974-01-01
The buckling analysis presented considers rectangular flat or curved general laminates subjected to combined inplane normal and shear loads. Linear theory is used in the analysis. All prebuckling deformations and any initial imperfections are ignored. The analysis method can be readily extended to longitudinally stiffened structures subjected to combined inplane normal and shear loads.