Research On Low Speed Impact Resistance Of Flax/Basalt Fiber Composite Laminates

Automotive lightweighting is an important way to reduce fuel consumption of fuel vehicles and increase the range of electric vehicles.The use of new lightweight materials is undoubtedly an important means to achieve this approach.Fiber-reinforced composites have excellent mechanical properties and are often considered as a substitute for traditional automotive steels.The advantages of fiber-reinforced composites depend largely on the fibers used.Flax fiber is a kind of plant fiber,and its high yield and renewable characteristics determine the huge advantage of flax fiber in cost,and flax fiber can be naturally degraded after being discarded,which is a very ideal green material.Basalt fiber is a new type of material processed from natural volcanic rock.It has similar properties to high-strength glass fiber but has a lower price.It can be directly integrated into nature after being discarded and is not harmful to the environment.Therefore,this article uses flax fiber and basalt fiber as reinforcement to prepare a fiber-reinforced composite laminate,combining test and finite element simulation to explore its low-speed impact resistance,analyze the effect of the layering sequence and layering angle on the low-speed impact resistance of the laminate,and analyze the impact of the impact position and impact energy on the low-speed impact response of the laminate.Finally,the material is applied to the inner and outer panels of the engine hood for basic application research.The specific research content of this article is arranged as follows:?1?The basic performance parameters of flax fiber composite laminates were obtained through experiments.Specific parameters include:longitudinal elastic modulus21.3Gpa,tensile strength 301Mpa,transverse elastic modulus 4.41Gpa,tensile strength25Mpa,shear elastic modulus 1.83Gpa,shear strength is 35.2Mpa.The sodium bicarbonate solution was used to alkalize the flax fibers.The test result found that within a given range,as the concentration of the solution increased,the flax fiber composite laminates'resistance to low-speed impact increased,but the energy absorption performance also decreased.The flax fiber composite laminates,basalt fiber composite laminates and flax/basalt fiber composite laminates were tested for low-speed impact resistance.The result showed that the basalt fiber composite laminates had the strongest low-speed impact resistance,and the flax fiber composite laminates have the best energy absorption,and the flax/basalt fiber composite laminates'low-speed impact resistance and energy absorption effect between the two.?2?Established a low-speed impact finite element model of composite laminates and verified the validity of the model.A low-speed impact finite element model of flax/basalt fiber composite laminates was established,and the contact force-time curves obtained by simulation and experiment were compared.The result shows that the two curves have good consistency,which proves that the finite element model is effective.The composite damage subroutine?Vumat?is established based on the three-dimensional Hashin criterion and the linear stiffness degradation method of fracture toughness to improve the rationality of the out-of-plane impact simulation of composite laminates.?3?Analysis of the effect of the layering sequence and layering angle on the low-speed impact resistance of the flax/basalt fiber composite laminates.The result shows that the laminates in the form of B₂F₄B₂ laminates have better resistance to low-speed impacts.It is also the smallest;the maximum displacement of the laminate with the lay angle of[0/45/90/-45°]₂ is the smallest,and its resistance to low-speed impact is the best,but the deformation energy absorption effect of the laminate is the worst.The impact of impact position and impact energy on the low-speed impact response of the laminate is analyzed.The result shows that the closer the impact position is to the constrained area,the greater the peak force generated by the impact.The material in this area cannot produce enough deformation to absorb energy,resulting in the laminate being impacted with the increase of impact energy,the peak load,maximum displacement,and energy absorption of the laminates have increased,but their energy absorption rate has shown a downward trend.?4?Pedestrian protection performance analysis of flax/basalt fiber composite laminates engine hood.With the goal of equating the basic static performance of the original engine hood after material replacement,a total of 16 layers of flax/basalt fiber composite laminates were determined,apply it to the inner and outer panels of the engine hood respectively for replacement,and perform head collision simulation of children's pedestrian.and applied to the inner and outer panels of the engine hood respectively for replacement and head collision of children.The simulation result shows that the protection performance of the child hood of the hood after replacing the inner panel meets the requirements of regulations and is better than that of replacing the outer panel,it also meets the requirement of lightweight.