Study on Failure Behavior of Spiral Spring for Automotive Suspension System
Received:June 20, 2021  Revised:July 16, 2021
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DOI:10.7643/issn.1672-9242.2021.08.017
KeyWord:spiral spring  failure  shot peening  folding defect  fatigue fracture
                          
AuthorInstitution
ZHANG Qiang-hong Southwest Institute of Technology and Engineering, Chongqing , China
CHEN Ke-zhong The Sixth Military Representative Office of the Amy Equipment Department in Chongqing, Chongqing , China
FU Yang-fan Southwest Institute of Technology and Engineering, Chongqing , China
WANG Chang-peng Southwest Institute of Technology and Engineering, Chongqing , China
CHEN Da-jun Southwest Institute of Technology and Engineering, Chongqing , China
MEI Hua-sheng Southwest Institute of Technology and Engineering, Chongqing , China
LIU Zheng-tao Southwest Institute of Technology and Engineering, Chongqing , China
DAI Ye Southwest Institute of Technology and Engineering, Chongqing , China
CONG Da-long Southwest Institute of Technology and Engineering, Chongqing , China
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Abstract:
      In order to put forward improvement measures, the causes of the failure of spiral springs for vehicle suspension are researched. The failure behavior of spiral spring is concluded based on the analysis of several tests such as chemical component test, hydrogen content test, non-metallic inclusion test, mechanical property test, fracture morphology analysis and microstructure analysis. The maximum shear stress is in the inner side of the specimen, where the stress concentration is easily caused. The elongation after fracture is low, and the brittle fracture can be seen. The decarburized layer and other original defects on the surface are not completely removed by shot peening, so the possibility of forming fatigue defects on the surface is increased. Due to shot peening, there are deep pits on the surface of the spiral spring, and obvious convex edges are formed on the edge of the pits, resulting in stress concentration. Under the action of stress, the end of the fold defect in the pits becomes the crack initiation area. Under the action of cyclic stress, the crack continues to expand and finally causes fatigue fracture. The shot size and pressure should be reduced, to avoid deep pits and sharp convex edges. In addition, the removal depth of surface layer in shot peening process should be increased appropriately. The heat treatment process should be adjusted to reduce the strength and improve the toughness of the material, so that the elongation after fracture can be more than 10%. The rolling process should be improved to eliminate the folding defects, and the detection of material defects also should be strengthened.
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