Evaluation of fatigue strength of carbon fiber reinforced plastics (CFRP) with various types of hybrid matrices

Abstract

Polymer composite materials (PCM) have found wide application in various industries due to the ability to create low-weight products with specified operational properties. During operation, composite products are exposed to static and cyclic loads, climatic and many other factors. Evaluation of the fatigue strength of composite materials and the influence of various additives and modifiers on it is an urgent scientific and practical task. The article describes the technology of obtaining PCM with various types of hybrid matrices formed by the main binder material and the material representing an independent "liquid" phase in the composite structure. Based on the analysis of the kinetics of curing, anaerobic polymer material (Loctite 638), silicone elastomer (Unisil-9628) and synthetic wax were selected as the materials of the components of the "liquid" phase. Fatigue strength assessment tests were carried out by applying cyclically varying tension-compression loads to the samples. The load during cyclic tests was 70% of the static tensile strength of the samples. The residual strength was evaluated by testing the tensile strength of the samples until complete destruction after cyclic loading. The results of fatigue strength tests of carbon fiber plastics with various types of hybrid matrices (formed by various components of the "liquid" phase) are presented. The analysis of the results showed that the use of an anaerobic polymer material as a component of the "liquid" phase of the hybrid matrix makes it possible to increase both the initial static strength of the material (by ~ 1%) and the residual strength after cyclic loading (by ~ 11%) compared with these indicators obtained during the testing of control samples. After performing cyclic loading, carbon fiber plastics with anaerobic polymer material and silicone elastomer have an increase in residual strength compared to previously performed static tensile tests by ~ 8% and ~13%, respectively. The use of an anaerobic polymer material and silicone elastomer as a component of the "liquid" phase makes it possible to increase the modulus of elasticity of carbon fiber plastics after cyclic loading by ~ 13% and 5%, respectively, compared with the results of preliminary static tests.