Vedenje kratkih vlaken C/PPS kompozitov pri lezenju

Abstract

Composite materials with a polymeric matrix reinforced by carbon fibres are nowadays widely used as high-tech structural materials with excellent mechanical properties (particularly their stiffness and strength). The application of this type of composite to structural parts exposed to thermal loading has recently been proposed. Such an application requires an investigation and analysis of the mechanical behaviour under long-term exposure to simultaneous thermal and mechanical loading. In this paper the measurements and results of the creep behaviour of a composite with a polyphenylene sulphide matrix reinforced with chopped poly-acrylonitrile carbon fibres (C/PPS) are presented. The measured compound is proposed for use as a structural material for a jet-engine frame in the aerospace industry and the internal parts of aircraft with possible thermal loading. A custom experimental device designed for the creep measurements of composite materials was used for measurements of the developing strain at a constant tensile stress and temperature. Short-term creep tests with continuous strain monitoring were performed at a constant stress level at several elevated temperatures below and above the glass-transition temperature of the matrix. The strain was measured using the digital image correlation (DIC) method. The measured data were processed to find the strain-to-time dependency and the creep-compliance-to-time dependency. The creep-compliance-to-time data were also fitted using Findley’s creep law for polymers to evaluate the model parameters and to analyse the applicability of the model for a PPS polymer reinforced with chopped carbon fibres.