Showing papers on "Micromechanics published in 1971"
TL;DR: In this paper, a generalized Duhamel-Neumann form of Hooke's law is used to develop laminated plate equations which include the effect of expansional strains, such as temperature, absorption by a polymeric matrix material of a swelling agent such as water vapor, and by sudden expansion of absorbed gases in the matrix.
Abstract: A generalized Duhamel-Neumann form of Hooke's law is used to develop laminated plate equations which include the effect of expansional strains. Such strains are induced in composite materials by temperature, absorption by a polymeric matrix material of a swelling agent such as water vapor, and by sudden expansion of absorbed gases in the matrix. Solutions to specific boundary value problems are presented for both symmetric and nonsymmetric laminates. Numerical results indicate that in addition to inducing residual stresses, expansional strains can substantially affect the gross response characteristics of a composite material.
211 citations
TL;DR: In this paper, a method for calculating internal stresses in rubber-modified polymers and for predicting elastic constants as well as a critical stress for onset of crazing is discussed, and a simple model is used to simulate the structure and behavior of the composite, and the necessary assumptions are listed.
Abstract: A method is discussed for calculating internal stresses in rubber-modified polymers and for predicting elastic constants as well as a critical stress for onset of crazing. A simple model is used to simulate the structure and behavior of the composite, and the necessary assumptions are listed. It is possible to account for interactions between particles which to date has been neglected in other analyses.
59 citations
01 Mar 1971
TL;DR: In this paper, a FORTRAN IV computer code for the analysis of multilayered fiber composite structural components is described, which can be used either individually or as a subroutine within a complex structural analysis/synthesis program.
Abstract: : A FORTRAN IV computer code for the micromechanics, macromechanics, and laminate analysis of multilayered fiber composite structural components is described. The code can be used either individually or as a subroutine within a complex structural analysis/synthesis program. The in-puts to the code are constituent materials properties, composite geometry, and loading conditions. The outputs are various properties for ply and composite; composite structural response, including bending-stretching coupling; and composite stress analysis, including comparisons with failure criteria for combined stress. The code was used successfully in the analysis and structural synthesis of flat panels, in the buckling analysis of flat panels, in multilayered composite material failure studies, and lamination residual stresses analysis.
36 citations
TL;DR: In this paper, a finite element analysis was used to calculate the internal stresses and deformations everywhere within spherically filled or porous ceramics and demonstrated the importance of these interactions on stress fields around the inclusions.
Abstract: A finite element analysis was used to calculate the internal stresses and deformations everywhere within spherically filled or porous ceramic materials. This analysis accounts for interactions between inclusions and demonstrates the importance of these interactions on stress fields around the inclusions. Modulus of elasticity and Poisson's ratio were calculated for porous and filled ceramics. The predicted modulus is compared with experimental data for two glass composites; the agreement is excellent.
27 citations
TL;DR: Theoretical and experimental results for the magnitude and distribution of interfiber stresses in a transversely loaded composite consisting of an elastic matrix reinforced with elastic fibers are presented in this article.
Abstract: Theoretical and experimental results for the magnitude and distribution of interfiber stresses in a transversely loaded composite consisting of an elastic matrix reinforced with elastic fibers are presented. Interfiber stress distribution is also given for an in plane shear load condition. The mathematical model consists of uniformly spaced circular fibers in a square array. An approximate solution is obtained for the interfiber stresses. Theoretical results are compared with results of a photoelasticity investigation, Fil'shtinskii's rigorous elasticity solution for a plate containing rigid circular inclusions, and with results of a rigorous elasticity solution for a three-dimensional problem. The present approximate solution provides good agreement with the experimental results and with the theoretical results obtained by other authors. The method of solution presented can be used for predicting interfiber stresses in composites with various shape fibers arranged in arbitrary arrays, as well as for investigating interfiber thermal stresses, elasto-plastic deformations, and residual stresses.
26 citations
TL;DR: In this paper, the point matching numerical method and its generalization, the method of boundary point least squares, have been successfully applied to numerous boundary value and eigenvalue problems.
Abstract: The point matching numerical method and its generalization, the method of boundary point least squares, have been successfully applied to numerous boundary value and eigenvalue problems. The present paper demonstrates the application of these techniques to problems in the micromechanics of fibrous composite materials, i.e. determination of elastic moduli and stress concentrations for parallel-fibre materials which are loaded transversely with respect to the fibres. The solution technique utilizes exact solutions of the governing equations of plane elasticity for each component fibre and its surrounding matrix material in a typical repeating section of the composite material. The continuity conditions for stresses and displacements between fibre and matrix and the repeatability conditions at the boundary of the repeating section are satisfied approximately in a pointwise manner. Some special numerical techniques which were found to be particularly useful in applying the point matching method to these problems are delineated. The method is demonstrated for composite materials having circular, elliptical and square fibres in regular, staggered arrays. Numerical results are given which show the accuracy of the method as well as stress concentration and composite elastic moduli data.
10 citations
6 citations
19 Apr 1971
5 citations
TL;DR: In this article, the influence of strain-hardening and grain size on the early stage of fatigue damage of polycrystal subjected to fluctuating stress is considered, and it is shown that the increase of the strainhardening rate and/or the decrease of the grain size decreases the rate of early fatigue damage.
Abstract: E arly fatigue damage is assumed to correspond to the build-up of local plastic shear strain. The influence of strain-hardening and grain size on the early stage of fatigue damage of a polycrystal subjected to fluctuating stress is considered. The calculations are based on a micromechanics theory proposed recently by the authors. It is shown that the increase of the strain-hardening rate and/or the decrease of the grain size decreases the rate of early fatigue damage. In order to produce 100 per cent local plastic shear strain for a given number of loading cycles, the range of the alternating stress decreases with increasing amounts of mean stress. This result is shown to be rather insensitive to the rate of strain-hardening and is found to lie between the values predicted by Gerber's parabolic law and by the modified Goodman linear law for fatigue failure.
3 citations