Matching Design And Performance Study Of Composite Leaf Spring For A Light Truck

In recent years,people have paid more and more attention to energy conservation and environmental protection,and with the continuous increase in the number of residential vehicles in my country,the state has also issued a series of policies to put forward higher requirements on vehicle energy consumption and emissions.Lightweight design can effectively meet the performance requirements of automobiles while reducing energy consumption and emissions.Material replacement is a very effective way to achieve automobile lightweight.The weight of the leaf spring accounts for 10%-20% of the unsprung mass of commercial vehicles.The use of composite materials to replace them in whole or in part can generally achieve at least 50% weight reduction,and at the same time can further improve the vehicle’s driving performance and reduce energy burn.In addition,in terms of fatigue life,composite leaf springs can generally be at least twice that of leaf springs,with good corrosion resistance and fracture safety.Therefore,the design and application of composite leaf springs is an important development direction for automobile lightweight.In this paper,composite materials will be used to replace steel,and the matching design and key performance of composite leaf springs will be studied,combined with theoretical simulation and bench tests,to verify the main performance of composite leaf spring assembly structure.The specific research content is as follows:First,determine the main structure and performance parameters of the composite leaf spring based on the technical parameters of the target vehicle and the leaf spring.Comprehensive analysis of relevant domestic and foreign research results and combined with the actual situation,design a composite leaf spring assembly structure with a steel plate structure,that is,an assembly plan including steel plate leaf spring,composite leaf spring,and other connectors.Select the manufacturing material of the composite leaf spring and trialproduce the composite laminate to obtain the performance parameters of the material,which lays the foundation for the matching optimization and simulation calculation in the following.Then,according to the relevant mechanics theory,a theoretical calculation model for the stiffness of the composite leaf spring is established.On this basis,a theoretical calculation model for the strength of the composite leaf spring is established based on the Tsai-Wu tensor criterion.A multi-objective optimization model for composite material sheets was established with the goal of stiffness,strength and quality parameters using genetic algorithms,and the corresponding weight coefficients were assigned to each sub-objective according to the optimization sequence,so as to obtain the optimal layup plan that meets the target performance requirements.Simulation optimization and trial production and assembly of composite material sheets provide a parameter basis.Second,the finite element analysis software Hyper Mesh and ABAQUS were selected to establish the finite element model of each leaf spring and connector in the composite leaf spring assembly structure,and complete the simulation calculation of stiffness and strength under various extreme conditions.The results show that the stiffness values of the composite leaf spring assembly and each leaf spring are within the reasonable design range,and the strengths of the assembly and leaf springs meet the performance requirements under various extreme driving conditions.Compared with the calculation results of the theoretical model established above,the calculation errors of the stiffness and strength of the assembly and each leaf spring are relatively small,which also verifies the correctness of the theoretical calculation model.Finally,the advantages and disadvantages of each composite material molding process are analyzed,combined with the existing technical conditions,the molding process is selected to complete the trial production of the composite material sheet in the composite leaf spring assembly structure and the assembly structure assembly.Set up a test bench,carry out the static stiffness and static strength bench test of the composite leaf spring assembly,and analyze the test data.The results show that the stiffness and strength of the composite leaf spring assembly meet the design requirements.It also shows that both theoretical model calculations and simulation calculations can more accurately predict and obtain the performance of the leaf spring.Analyze the fatigue failure mechanism of the composite leaf spring,and improve and optimize the original layup sequence based on the idea of the sandwich layup unit.After the optimization,the composite leaf spring assembly was subjected to 200,000 cycles of cyclic load,and no component was damaged,and no delamination occurred on the surface of the composite sheet,indicating the correctness and effectiveness of the fatigue optimization method in this paper.