Modeling the stress-strain state of variable-thickness composite shells and plates

A model for calculating the stress-strain state of variablethickness composite shells has been developed, based on assumptions such us the classical theory of Timoshenko-Mindlin shells. In the proposed model, the plate thickness is given by a function of curvilinear coordinates and is directly considered in the derivation of the equilibrium equations of the plate. The general equations of the theory of variable-thickness composite plates are derived. The article analyses the solution of the problem of plates bending under uniform pressure considering the variable thickness. For the numerical solution, the finite difference method (FDM) has been applied to the system of differential equations with matrix coefficients. For the resultant algebraic system, the FDM uses the tridiagonal matrix algorithm in computing the solution. The calculation results are compared with a plate of constant thickness. It is shown that the effect of thickness variability is quite significant

Modeling the stress-strain state of variable-thickness composite shells and plates

A model for calculating the stress-strain state of variablethickness composite shells has been developed, based on assumptions such us the classical theory of Timoshenko-Mindlin shells. In the proposed model, the plate thickness is given by a function of curvilinear coordinates and is directly considered in the derivation of the equilibrium equations of the plate. The general equations of the theory of variable-thickness composite plates are derived. The article analyses the solution of the problem of plates bending under uniform pressure considering the variable thickness. For the numerical solution, the finite difference method (FDM) has been applied to the system of differential equations with matrix coefficients. For the resultant algebraic system, the FDM uses the tridiagonal matrix algorithm in computing the solution. The calculation results are compared with a plate of constant thickness. It is shown that the effect of thickness variability is quite significant

Thermomechanics of composite structures under high temperatures

This pioneering book presents new models for the thermomechanical behavior of composite materials and structures taking into account internal physico-chemical transformations such as thermodecomposition, sublimation and melting at high temperatures (up to 3000 K). It is of great importance for the design of new thermostable materials and for the investigation of reliability and fire safety of composite structures. It also supports the investigation of interaction of composites with laser irradiation and the design of heat-shield systems. Structural methods are presented for calculating the effective mechanical and thermal properties of matrices, fibres and unidirectional, reinforced by dispersed particles and textile composites, in terms of properties of their constituent phases. Useful calculation methods are developed for characteristics such as the rate of thermomechanical erosion of composites under high-speed flow and the heat deformation of composites with account of chemical shrinkage. The author expansively compares modeling results with experimental data, and readers will find unique experimental results on mechanical and thermal properties of composites under temperatures up to 3000 K. Chapters show how the behavior of composite shells under high temperatures is simulated by the finite-element method and so cylindrical and axisymmetric composite shells and composite plates are investigated under local high-temperature heating. The book will be of interest to researchers and to engineers designing composite structures, and invaluable to materials scientists developing advanced performance thermostable materials

Finite element modeling of integral viscoelastic properties of textile composites

The problem of modeling the effective integral viscoelastic properties of unidirectional composite materials is considered. To calculate the integral properties of viscoelasticity, the Fourier transform and the inverse Fourier transform are used, as well as the method of asymptotic averaging for composites with steady polyharmonic vibrations, and a finite element algorithm for solving local problems of the viscoelasticity theory on the periodicity cell of the composite. To obtain the material constants, a method of approximation of the Fourier images of the relaxation and creep kernels is proposed, which makes it possible to avoid the numerical error of the inverse Fourier transform