Effects of Material Nonlinearities on Design of Composite Constructions-Elasto-Plastic Behaviour.

Aleksander Muc

doi:10.3390/ma13071792

Abstract

Usually, the design of composite structures is limited to the linear elastic analysis only. The experimental results discussed in the paper demonstrate the physical non-linear behaviour both for unidirectional and woven roving composites. It is mainly connected with the micromechanical damages in composite structures, particularly with the effects of matrix cracking modeled in the form of elastic-plastic physical relations. In the present paper, the effects of both physical and geometrical non-linearities are taken into account. Their influence on the limit states (understood in the sense of buckling or failure/damage) of composite structures is discussed. The numerical examples deal with the behaviour of composite pressure vessels components, such as a cylindrical shell and the reinforcement of the junction of shells. The optimisation method of the reinforcement thickness is also formulated and solved herein.

Highlights

It is well known that the polymeric matrix of fibre-reinforced plastics (FRP) exhibits significant non-linear stress/strain behavior
It should be emphasised that for our purposes, the character of deformations is the most important and significant effect and not the numbers, since they are directly related to the type of composite materials
The necessity of taking into account of both geometrical and physical non-linearities in the design of pressure vessels made of fibre-reinforced plastics is pointed out in the present paper

Summary

Introduction

It is well known that the polymeric matrix of fibre-reinforced plastics (FRP) exhibits significant non-linear stress/strain behavior (the σ–ε diagram). The non-linearity may even be detected upon initial loading of the material and continue until catastrophic failure. This non-linear mechanical response is mostly due to the non-linear constitutive behavior of the polymer matrix, microcracking of the matrix material, fibre/matrix interface debonding, and interlaminar delamination. This effect may be enhanced by fibre orientations especially for fibres oriented at 45◦ where a typical plastic hardening is observed. There has been a considerable amount of research performed on the non-linear behavior of woven fabric composites at the meso-mechanical level using numerical [4,5] and analytical approaches [6,7]

Methods

Results

Conclusion