Study On Fatigue And Mechanical Properties Of Carbon Fiber Composite Laminates After Fire

Carbon fiber reinforced resin matrix composites are widely used in aerospace,transportation,energy generation,marine engineering and other fields because of their superior performance and unique process characteristics such as light weight,high specific strength,high specific modulus,fatigue resistance,high temperature resistance,corrosion resistance,and designability.With the increase of the application ratio of composite materials,it makes the fatigue problem of composite structures appear continuously,while the epoxy resin base also means that its composite materials are flammable,and the occurrence of air disasters in recent years makes the fire problem has been the core concern of the aviation industry,so it is especially important to study the fatigue performance and the mechanical properties of carbon fiber composite laminates after fire.Many scholars at home and abroad have studied the fatigue problem,but there is little research on the fatigue performance of high-strength carbon fiber composite laminates with different layups,and there is also a lack of research on the fire reaction characteristics and post-fire mechanical properties of three-dimensional woven laminates.In this paper,the following work has been carried out using high-strength carbon fiber composite laminates with different layups and three-dimensional twill weave laminates as research materials.1.Static tensile-compression tests and tensile-compression fatigue life tests of carbon fiber composite laminates with 0° and ±45° layups were conducted with T700 carbon fiber composite laminates as the study materials,and the tensile-compression strength and fatigue life of the materials under different load levels were tested,and it was found that the 0° layup materials were brittle damage and the ±45° layup materials were plastic damage under static load.The fatigue life and fatigue damage characteristics of the high-performance carbon fiber materials with different layups were analyzed,and it was found that the degree of stiffness degradation and the main damage forms of the two materials were very different with the increase of cycle cycles,and the 0° specimen retained certain stiffness at the end of fatigue,while the ±45° specimen showed more serious delamination and fiber distortion.2,using three-dimensional woven twill T300 carbon fiber composite laminate as the research material,the experimental material was firstly prepared by hot pressing with prepreg,and the experiments used two kinds of 3K twill prepreg with flame retardant resin and common resin to study its damage form after fire at different temperatures,and the damage evolution process was analyzed by C sweep and SEM,etc.It was found that the damage after fire was mainly manifested in the damage area on the surface of the specimen and the thickness It is found that the damage after fire is mainly in the surface area of the specimen and the layered damage in the direction of thickness,and the damage of flame retardant resin laminate is less than that of ordinary resin laminate under the high temperature fire conditions of both materials.The internal damage patterns of the laminates were obtained by C-scan and SEM damage detection methods,and it was found that the fire damage would change the energy absorption mechanism of the laminates,thus increasing the peak impact force and changing the impact damage morphology.The results showed that both fire and impact damage significantly reduced the residual compressive strength of the laminate,and the transverse cracks of the laminate with fire damage were more likely to form plastic kink in the delamination zone of the flame degradation zone during the compression process.band.