Study On Mechanical And Hydrothermal Aging Behaviors Of Flax-carbon Hybrid Composite Plates

With the development of sustainable concepts such as energy saving,environmental protection and green,structural materials need to take into account the whole life cycle performance on the basis of mechanical properties.Composite materials can be designed,and different raw materials and manufacturing processes can better meet the needs of the sustainable development of engineering structures.Flax fiber is a kind of natural fiber,which has the advantages of low energy consumption,degradable,renewable and low price.In recent years,it has been widely used in automobile,aerospace and other fields.Compared with synthetic fiber,flax fiber has low mechanical properties and poor hygrothermal resistance.Carbon fiber has excellent mechanical properties,fatigue resistance and corrosion resistance,but it has low ductility,poor toughness and high cost.In this paper,the interlaminar hybrid composites were prepared by mixing flax fiber cloth with a small amount of carbon fiber cloth,and the mechanical properties and hygrothermal resistance were studied to reveal the hybrid effect.The goal is to develop a high-performance,low-cost and sustainable hybrid fiber polymer composite(HFRP)through fiber hybrid design,which can give full play to the advantages of the two materials and avoid the disadvantages.The main research contents and achievements are as follows:Firstly,the static mechanical properties of HFRP were studied.It is found that the mechanical properties of HFRP are between carbon fiber composites(CFRP)and flax fiber composites(FFRP),showing a positive hybrid effect.The arrangement of carbon fiber in the outermost layer shows higher strength,and the tensile fracture strain increases with the arrangement of linen fiber in the outermost layer and carbon fiber in the interval.Secondly,the evolution of mechanical properties of HFRP in moisture and heat environment was experimentally studied.The results show that the water absorption of HFRP decreases and the degradation rate of mechanical properties is lower than that of FFRP.Thirdly,the low-speed impact resistance and damping performance of HFRP are experimentally studied.It is found that HFRP has a peak load close to that of CFRP and higher energy absorption when it is penetrated by impact force.The loss factor and modal damping coefficient of HFRP are higher than those of CFRP,which is closely related to the mode of interlaminar mixing.In conclusion,mixing a small amount of carbon fiber can effectively improve the mechanical properties and hygrothermal resistance of FFRP.It is of great significance to improve the properties of FFRP through fiber mixing and expand its application in engineering structures.