Study On The Strength Of Glass/Carbon Fiber Hybrid Composites Under Hydrothermal Environment

At present,with the development of human society and science and technology,the use of hybrid composite materials is becoming more and more extensive and has been applied in various industrial fields.To adapt to social development and save production costs,carbon fiber and glass fiber are sometimes used to reinforce the same resin matrix,and glass/carbon fiber hybrid composite materials with excellent specific strength,specific stiffness,and fracture toughness can be obtained.However,its use in engineering is often subject to the combined effects of the hydrothermal environment and external loads,which seriously affects the strength of the composite material.Therefore,it is of great engineering importance to carry out strength studies of glass/carbon fiber hybrid composites under a hydrothermal environment.In this paper,from the perspective of macro mechanics,a function containing hydrothermal variables is established through the strength and stiffness of the composite lamina.Based on the classical laminate theory in a hydrothermal environment,the stiffness reduction correction method and the Hofmann strength failure criterion.A strength model for glass/carbon fiber hybrid composite laminates was developed.The strength of symmetric laminates of glass/carbon fiber hybrid composites and asymmetric laminates of glass/carbon fiber hybrid composites under a hydrothermal environment was investigated.The details of the study and the conclusions are as follows:(1)The strength calculation program of glass/carbon fiber hybrid composite symmetric laminate under a hydrothermal environment was written using MATLAB software,and the influence law of different layup methods,layup thickness,and layup structure on the tensile strength of glass/carbon fiber hybrid composite symmetric laminate under hydrothermal environment was investigated.It was found that the tensile strength of the symmetrical laminate of the glass/carbon fiber hybrid composite with the lay-up method of(0_G/90_C)_4Swas better under the same hydrothermal environment.In the layup design,the tensile strength gradually decreases with increasing mass fraction of 45°or 90°plies when combining 45°or 90°plies with 0°plies,respectively,under the condition that the total number of plies of glass/carbon fiber hybrid composite symmetrical laminates remains unchanged.Under the hydrothermal environment,with(0_C/90_G)_mas the incremental unit layer,with the increase of the m value,the tensile strength of the glass/carbon fiber hybrid composite symmetric laminate increases.(2)The effects of temperature,layup thickness,and layup sequence on the bending strength of glass/carbon fiber hybrid composite symmetric laminates subjected to bending moment load Mx in a hydrothermal environment were investigated.The study shows that the bending strength of the glass/carbon fiber hybrid composite symmetrical laminate gradually decreases with the increase of ambient temperature within the temperature of20??110?in dry and wet state environments,and the more obvious the influence of humidity on the bending strength of the laminate.Under the dry and wet state environment,the glass/carbon fiber sandwich hybrid composite symmetrical laminate takes the carbon fiber/epoxy resin monolayer as the surface layer and the glass fiber/epoxy resin monolayer as the core layer,and its bending strength is better.The number of groups of(0°/90°)or(0°/45°)in the symmetrical laminate of glass/carbon fiber hybrid composite should be increased as much as possible within the engineering thickness to enhance its bending strength.(3)Based on the classical laminate theory under a hydrothermal environment,the existence of coupled stiffness matrix of composite asymmetric laminates was considered,and the strength calculation program of glass/carbon fiber hybrid composite asymmetric laminates was written using MATLAB.The tensile and flexural strengths of asymmetric laminates of glass/carbon fiber hybrid composites under a hydrothermal environment were calculated.The effect of temperature and layup ratio on the strength of glass/carbon fiber hybrid composite asymmetric laminates under a hydrothermal environment is discussed.The study showed that the tensile strength and bending strength of glass/carbon fiber hybrid composite asymmetric laminates decreased more significantly with the increase of temperature in the hydrothermal environment and were affected by the temperature to a greater extent.The higher the proportion of 0°plies in the asymmetric laminates of glass/carbon fiber hybrid composites the higher their tensile and flexural strengths under a hydrothermal environment.When the 90°plies are stacked continuously,the matrix cracking in the 90°plies when the glass/carbon fiber hybrid composite asymmetric laminate is subjected to tensile loading will lead to increasingly severe local stress concentrations near the fibers of the other plies,thus gradually reducing the tensile strength of the glass/carbon fiber hybrid composite asymmetric laminate.