Journal of Failure Analysis and Prevention

, Volume 14, Issue 2, pp 139–147 | Cite as

Failure Analysis and Design Optimization of the Steady Rest Hanger Rod Pipe Assembly

  • Bharat Joshi
  • John George
  • Brian Rose
  • Yin Chen
Case History---Peer-Reviewed


This article investigates the failure of the steady rest hanger rod pipe assembly weld joints of an automotive exhaust system. Rig testing of the exhaust system showed the presence of crack at the steady rest hanger rod and brace weld joints. Metallurgical investigation was performed in order to determine the root case of failure and contribution factors. Metallurgical analysis methods included visual examination, thickness measurements, optical and scanning electron microscopy, chemical analysis of the material and weld evaluation. A CAE analysis was performed to simulate the rig test. Finite element simulation of the system also showed high damage at the steady rest hanger and brace weld locations. A DOE study was conducted to identify the design variables that could impact the dynamic response of the system like the thickness of the parts, the weld characteristics of joints, etc. Design changes were proposed; to improve the fatigue life of steady rest hanger rod pipe assembly based on the results of DOE-based study. The new design was analyzed using finite element analysis and compared with the original design for fatigue life, which showed a considerable improvement in the durability of the joint.


Automotive exhaust systems Steady rest hanger rod Failure analysis Fatigue failure Finite element analysis Design of experiments (DOE) 


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Copyright information

© ASM International 2013

Authors and Affiliations

  • Bharat Joshi
    • 1
  • John George
    • 2
  • Brian Rose
    • 1
  • Yin Chen
    • 2
  1. 1.Materials Engineering and Warranty Analysis LaboratoryFaurecia Emission Control TechnologiesColumbusUSA
  2. 2.Computer Aided EngineeringFaurecia Emission Control TechnologiesColumbusUSA

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