Study Of The Hygrothermal Environment On Mechanical Properties Of Carbon Fiber Rein Based Laminates

The composite material as a new material has been widely used in various industries,such as aerospace,automotive and civilian areas of life and other fields,and the carbon fiber is the most commonly used composite materials,due to its excellent overall performance.With the rapid development and application of composites,more and more composites are used in harsh environments,for example hygrothermal environment in real life.Long-term in the hot and humid environment of composite materials,such as carbon fiber pipes,composite gas cylinders,the material will produce hygrothermal stresses and aging phenomenon,which can undermine the internal properties of materials and reduce the capacity for resisting external damage load.So it is necessary to study the effect of hygrothermal environment on the mechanical properties of composite materials,and to take some protective measures.This article is based on the elasticity mechanics,the fracture mechanics and the classical laminated plate theory,and the research method is based on the combination of experiment and simulation.In the experiment,CCF300 / epoxy(5228)composite laminates were used as the samples and three experiments were carried out.First,the basic performance parameters of the composite laminates were tested which according to the relevant experimental standard,and the basic parameters such as strength and modulus of the material were obtained.Then,the moisture absorption test of the carbon fiber laminate was carried out,and the moisture absorption curve was obtained.It was found that the hygroscopic behavior basically met Fick's second law,and the moisture concentration and diffusion rate were calculated.Finally,the specimens which were treated by four different hygrothermal environment were subjected to tensile and compression and other tests,and then the effects of temperature and humidity on the three kinds of mechanical damage were summarized by comparing the failure load and displacement curve.This article mainly used the finite element analysis software ABAQUS to carry on the numerical simulation,and the simulation was mainly divided into two parts.The first part was to simulate the progressive damage of the structure of carbon fiber composite laminates at room temperature by using Hashin damage criterion which can simulate the fiber tensile,fiber compression failure,matrix cracking and matrix crushing,and at the same time delamination damage was simulated by the cohesive element.Finally,the damage distribution diagram and failure load value of the material were obtained.The second part was to study the constitutive relation model of composite laminates in hygrothermal environment,combining with the theory of heat conduction and mass diffusion.Based on the heat transfer and mass diffusion module in ABAQUS simulation software,the moisture absorption and hygrothermal stresses of the composites were simulated to obtain the moisture concentration distribution and moisture diffusion curve,as well as the hygrothermal stresses distribution diagram.Finally,the experimental and simulation results show that the influence of humidity is greater than the temperature when the temperature is lower than the curing temperature of the material.At the same time,the damage model and the moisture absorption model of the laminated plate are proposed,which verifies the correctness of the model.Therefore,it makes up for the disadvantages of traditional hot and humid experimental methods,such as long cycle and difficult water distribution measurement.