New method for predicting residual thermal stress of planar-knitted composite material

Abstract

The invention relates to a new method for predicting the residual thermal stress of a planar-knitted composite material, which comprises the following three steps of 1. selecting a minimum repetitive unit as a representative volume element according to the planar-knitting mode of a fiber bundle so as to determine the cell-body unit of the fiber bundle, and obtaining a simplified cell-body unit model according to the contraction deformation and stress conditions of component materials, i.e. a basal body and fibers, in the processes of cooling and solidification on the basis; 2. analyzing the stress of the basal body and the fibers in the cell-body unit according to the contraction-deformation compatibility conditions of the component materials i.e. the basal body and the fibers in the processes of cooling and solidification, and obtaining the constitutive relation between the thermal deformation of the component materials and the internal force of the cell-body unit so as to establish the thermal-stress analytic model of a planar-knitted composite-material single-layer plate; 3. establishing the thermal-stress equation of the planar-knitted composite-material single-layer plate according to the thermal-deformation compatibility conditions of the planar-knitted composite-material single-layer plate and a pure basal-body layer, and predicting the macroscopic residual thermal stress of a planar-knitted composite-material laminated plate through the performance of the component materials.

Description

technical field [0001] The invention relates to a new method for predicting the residual thermal stress of a plane braided composite material, which belongs to the technical field of composite materials. Background technique [0002] During the processing and application of composite materials, due to the different thermal expansion coefficients of the matrix and fibers and the influence of processing conditions, residual thermal stress inside the composite material will be generated. Residual thermal stress has an important influence on the mechanical properties of composite materials. The residual tensile stress in the matrix and the residual compressive stress in the fibers will cause the material to enter the yield state in advance under the action of tensile load, thereby reducing the strength of the composite material. Over the years, people have carried out in-depth research on the residual thermal stress of composite materials through experiments, numerical simulatio...

AI Technical Summary

Problems solved by technology

Residual thermal stress has an important influence on the mechanical properties of composite materials. The residual tensile stress in the matrix and the residual compressive stress in the fibers will cause the material to enter the yield state in advance under the action of tensile load, thereby reducing the strength of the composite material.

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