Study On The Strength And Toughness Structure Of Resin Based Glass Fiber Reinforced Automobile Plate Spring

Thermosetting resin-based glass fiber reinforced composite material(hereinafter referred to as GFRP)has the characteristics of high strength,impact resistance,and corrosion resistance,and can adapt to the working environment of high bearing capacity,large impact and high fatigue cycles.It has become a trend to replace the lightweight design of automobile plate spring with this kind of composite leaf spring.However,the interlaminar weakness of GFRP plate springs is prone to interlaminar delamination,interlaminar fracture and other damages in the manufacturing process and the use process,and this kind of damage is difficult to directly detect,which greatly affects the reliability of the use of GFRP plate springs.Therefore,improving the interlaminar fracture toughness of GFRP plate springs has very important practical significance.Based on this,this paper has studied the interlaminar fracture toughness of GFRP plate springs,aiming to improve the interlaminar toughness and fatigue life of GFRP plate springs when they meet the stiffness requirements.First,five types of toughened structure laminates,including staggered offset type,staggered type,half-tile offset type,comb type,and brickwork type,were designed,and the five toughened structures were tested through type II interlaminar fracture toughness experiments,the fracture toughness of the composite panel was compared and analyzed,and the experiment found that the toughening effect of the brick structure laminate was the best,therefore,through the type?and type?interlaminar fracture toughness experiments,the geometric parameters that affect the toughening effect of the brick laminate structure the length of the slit and the distribution density of the slit are studied,and it is found that the values of G_IC and G_IIC are larger for the samples with shorter and more densely distributed slits in the three groups of designed variables,that is,the interlaminar toughness of GFRP laminates is enhanced.Then,in view of the force condition of the front leaf spring of a tractor,based on satisfying the replace ability and the performance of the whole vehicle,the composite material leaf spring stiffness theoretical model and the relevant parameters of the leaf spring are used to determine the size of each part of the GFRP leaf spring,and then determine the structure of the whole spring body;after that,the different GFRP leaf spring joint types were compared,and finally,the rubber and screw hybrid connection method was selected to connect the steel coil lugs and the spring body end together,based on ensuring that the joint strength meets the requirements,the geometry of the joint structure was determined parameter.In order to avoid stress concentration caused by drilling,a metal splint is used as a positioning and a force transmission device for the spring body.Finally,a three-dimensional model of GFRP plate spring was established based on the combination of the above structures,and a three-dimensional finite element static analysis model of GFRP plate spring was established to analyze its stiffness.The simulation results are in good agreement with the theoretical analysis results,and the weight of the designed GFRP plate spring is reduced by60.85%compared with the original plate spring.Finally,on the basis of the three-dimensional model of the GFRP leaf spring,considering the huge number of layers and the ultimate goal is to compare the mechanical properties of the specimens,the scaled size of 1:5 was used for the production of leaf spring specimens.Through the three-point bending pressure experiment,the static stiffness of the shrinkage sample of the brick structure GFRP leaf spring and the shrinkage sample of the untoughened structure GFRP leaf spring were compared,the results show that the static average stiffness of the former is reduced by 8.4%compared to the latter.Then through the three-point bending high-frequency fatigue experiment,the fatigue performance of the shrinkage sample of the brick structure GFRP leaf spring and the non-toughened structure GFRP leaf spring was compared.The results show that under the same load,the fatigue life of the former is increased by 28.99%on average compared to the latter.In addition,it is found from the final state of the sample that:unlike the GFRP leaf spring with no toughened structure,which has a catastrophic failure,the brick structure GFRP leaf spring can still maintain the integrity of the appearance,so fatigue damage the post-brick structure GFRP leaf spring scaled-down sample was tested for residual stiffness,and it was found that it still possessed 43.52%of the original stiffness.