Fracture Failure of Oil-Pipes of Truck Diesel Engine Boost Compensator
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Two fractured oil-pipes of truck diesel engine boost compensators were received for failure analysis. Fracture occurred at the connection location of the pipe end with its casing-pipe wherein the positioned spot-welding was conducted. Fatigue fracture is the main failure mode of the two pipes. The chemical composition and the microstructure and the tensile properties of pipe materials are in accordance with the specification. However, the wider spacing of fatigue striations on the fracture surfaces and the shorter service life of pipes indicate that the ultimate strength of the specified material does not meet practical operating load with greater stress amplitude. The fatigue cracks initiated because of stress concentrations resulting from the combined effect of geometry configuration and high stiffness by the positioned spot-welding at the connection location of the pipe end and its casing-pipe.
KeywordsOil-pipe Fatigue fracture Stress concentration Low tensile strength
The project is supported by “the Fundamental Research Funds for the Central Universities (No. 3132014323).”
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