Experiment And Finite Element Analysis Of Strength Design For Bicycle Pedal

This thesis focused on bicycle pedal and carried out an experimental study and CAE structure optimization analysis on the static load strength,fatigue strength and impact strength of the bicycle pedal with reference to the theoretical knowledge of material mechanics,fatigue strength,fracture mechanics and impact dynamics.The main contents are described as follows:(1)The quasi-static tensile test on the pedal mandrel(made of 10B21 alloy structure steel)was performed using MTS universal testing machine,the basic mechanical properties of the material was obtained and the effect of heat treatment process on its mechanical properties was analyzed;these mechanical properties will be used for the subsequent CAE analysis model.The test standard for static load strength of bicycle pedals in the prevailing standards was briefly introduced.According to this test standard for static load strength,the finite element model of bicycle pedals was established,the finite element analysis of static-load compression was performed on the middle area,ends and sides of the pedal respectively,and the stress distributions of critical parts were obtained.Based on the analysis results,the weakest areas of relevant parts were identified to provide an important instruction for the design optimization of bicycle pedals.(2)The test program for fatigue strength of the pedal mandrel was prepared on my own,the experimental study on fatigue resistance performance of the pedal mandrel was completed to get its S-N curve and fit into a mathematical expression.The metallographic analysis and the microscopic analysis of the pedal mandrel fracture due to fatigue break were performed using fracture failure technique,so as to reveal the microscopic mechanism of fatigue break.Based on the experimental study,a finite element analysis was performed on fatigue strength of the pedal mandrel,and the structural design and optimization of the pedal were implemented according to the analysis results,so as to meet the design specifications.(3)Instron small hammer was used as the loading test device,the impact loading test bench for the bicycle pedal was designed on my own,the impact test studies on pedal mandrel and the pedal body were carried out respectively,the impact time history curve and the deformation displacement time history curve of the pedal mandrel were obtained using the strain-gauge force transducer and the digital image correlation-based contactless deformation testing technology,and the effects of hammer drop height,hammer head quality,hammer head impact direction and position were discussed.The findings show that the test results will provide basic experimental parameters for the impact performance assessment of the bicycle pedal and give an instruction for the design and optimization of impact performance of the bicycle pedal.(4)Based on the hammer test results,a finite element analysis of impact performance of the bicycle pedal was performed using ANSYS/LS-DYNA transient dynamic finite element software,a comparative study between the calculation results and the test results was made to verify the reliability of finite element calculation and identify the stress distributions for weak areas of the bicycle pedal subject to impact load,the simulation results were basically consistent with the test results.Based on the test and simulation results,an optimization design of the bicycle pedal was performed,and another test was carried out on the optimized product to prove the effectiveness of the optimization.