| With the rapid development of the automotive market,the automobile has become an essential tool for people.At the same time,the demand for energy saving and environmental protection of automobile is getting higher and higher.The lightweight of the automobiles can improve the fuel economy,and it becomes an important research project which complies with requirements of energy saving and environmental protection in the new era.By replacing the steel leaf spring of light vehicle with the basalt fiber composite leaf spring,more than 50% weight can be reduced on the basis of satisfying the performance of the whole vehicle.The application of basalt fiber as a new type of environmental protection fiber material on the auto leaf spring is of great significance.Basalt fiber composite material was selected as the manufacturing material of plate spring in this paper,through analyzing the structure and static and dynamic characteristics of basalt composite leaf springs,the forward design of the basalt fiber composite leaf spring was put forward.Firstly,in order to obtain the basalt fiber composite leaf spring which satisfied the performance of the entire vehicle,the stiffness model of the composite leaf spring was established by using the related knowledge of laminate theory and mechanics of materials.And based on the theoretical knowledge,the MATLAB program was written.Based on the known mechanical properties and structural parameters of composite materials,the stiffness of the composite leaf spring was obtained,which provided the theory base for verifying the correctness of the structural design in the later period.Secondly,on the basis of satisfying the replaceability,the spring body structure of the basalt fiber composite leaf spring was designed by the concept of equivalent modulus.Compared with the advantages and disadvantages of different type of joint,the connection of the metal joint and the spring end was determined,which combined the mechanical connection with the cementing connection.The structural parameters of the contact part of the joint and the spring body were reasonably designed.In order to avoid the stress concentration in the middle of the spring body caused by the bolt connection,the boss structure was arranged in the middle of the spring body to cooperate with the upper and lower clamps,which could ensure the reliable transmission of the longitudinal load and the positioning between the spring body and the lower clamp can be ensured.The three-dimensional solid model of the basalt fiber composite leaf spring was established using CATIA.Then,the static characteristics of the basalt fiber composite leaf spring were simulated and analyzed by finite element method.The simulation results showed that both the static stiffness and static strengths met the requirements,which verified the correctness of the structural design.At the same time,the lamination scheme of the basalt fiber composite leaf spring was brought into the theoretical model of stiffness to obtain the theoretical value,thus the correctness of the structural design was also verified from the view of theoretical point.Finally,due to the fact that the leaf spring mainly bore dynamic loads during actual movement,the key dynamic properties of the leaf spring needed to be studied in order to better simulate the actual situation.The modal analysis of the basalt fiber composite leaf spring was analyzed by the finite element simulation method.According to the obtained low-order natural frequency and modal shapes,it was preliminarily judged that it would not resonate with road excitation and so on.The basic concept of damping and the damping mechanism of composite materials were introduced,then the first three orders' loss factor were obtained from the material damping test of basalt fiber laminates.The finite element simulation results were compared with the test results to verify the correctness of the damping simulation model,thus the damping ratio of the basalt fiber composite laminate was determined. |
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