Damage accumulation and strain of fiber reinforced composites

In design of thin-walled structures of fiber reinforced composites it is necessary a reliable determination of resistance to load-bearing exposures. The model representations of damage accumulation have been described and that adequate description with the aid of hereditary type relations has been shown. The approach allowing us to perform nonlinear strain estimation has been suggested. As the initial readings the elastic properties of the layer and stress-strain curves have been used. Matrix algorithms of constitutive equations construction for unidirectional and layered composites have been elaborated. The approaches can be used in strength design of fiber reinforced materials and mechanical behavior prediction of composite materials and its members

A model of nonlinear strain and damage accumulation in polymer composites

This paper presents a model to predict a nonlinear strain of the carbon laminate; the model is based on the relations between the theory of laminated plates and the non-linear approximation of deformation curve of unidirectional layer at the shear in the layer plane. The explicit expressions of stiffness and compliance matrices were obtained via multiplying the matrices that correspond to the elastic characteristics by the matrices, considering the non-linear properties of the laminate. The paper suggests an approximation option for the non-linear properties of the layer at the shear using an exponential function. Some considerations on damage accumulation in carbon laminates were made

Analysis of sensitivity of elastic characteristics of unidirectional carbon fiber specimens with thermoplastic matrix to loading rate at high temperature

The problem of assessing the sensitivity of unidirectional carbon fiber reinforced plastics to loading rate is considered. As a rule, when the loading rate changes, the stress-strain curves for unidirectional CFRP specimens under loading at different off-axis angles change due to the rheological properties and physical nonlinearity. An attempt is made to reveal the degree of anisotropy sensitivity of a unidirectional carbon fiber reinforced plastic with thermoplastic matrix at an elevated temperature in the range of changes in the loading rate by two orders of magnitude both in stress and in strain

Analysis of sensitivity of elastic characteristics of unidirectional carbon fiber specimens with thermoplastic matrix to loading rate at high temperature

The problem of assessing the sensitivity of unidirectional carbon fiber reinforced plastics to loading rate is considered. As a rule, when the loading rate changes, the stress-strain curves for unidirectional CFRP specimens under loading at different off-axis angles change due to the rheological properties and physical nonlinearity. An attempt is made to reveal the degree of anisotropy sensitivity of a unidirectional carbon fiber reinforced plastic with thermoplastic matrix at an elevated temperature in the range of changes in the loading rate by two orders of magnitude both in stress and in strain

Numerical analysis of wave processes under high-speed impact on an object from CFRP

Numerical simulation of the impact of an aluminum particle on a composite medium was carried out. Carbon fiber reinforced plastic (CFRP) laminates T300/69 were used as a research object. The behavior of CFRP was analyzed at an impact velocity of 11 km/s and an aluminum particle mass of 1 g. The composite layers were located in planes oriented perpendicular to the direction of reinforcement. The Smoothed-particle hydrodynamics (SPH) method in conjunction with Ansys Autodyn was used for numerical modeling. Since large deformations and fracture of the objects were observed at such high impact velocities, which indicated a violation of the continuity of the material, that makes it incorrect to use of traditional mesh methods. The dependence of the shock wave propagation velocities in CFRP on time was obtained. The minimum thickness of the protective screen made of CFRP was estimated