engleski

Hydraulic torque wrench adapter failure analysis

Flaw appearance, crack occurrence and consequential failures are of serious concern in any mechanical design process. Once failed, parts can be analysed in order to determine the causes of failures. Therefore, failure analysis proves to be a valuable tool in design improvement. This research deals with a failure of hydraulic torque wrench square drive adapter. It is a 1.5″ size adapter capable of handling 15, 500 Nm torque. There has been a considerable number of identical failures so an attempt was made to determine the cause. Failure analysis was performed using experimental and numerical approach. Visual examination revealed the location and path of the fracture, while optical microscopy was used to inspect fracture surface and reveal possible flaws. Detailed scanning electron microscopy (SEM) examination at suitable magnifications was employed to characterize fine microstructure of the fractured surface and reveal flaws that served as crack initiation points. Chemical composition of the material was determined using optical emission spectrometer with glow discharge source (GDS) sample stimulation. Maximum tensile strength of the material was derived from the performed hardness test results. Further research employed finite element (FE) analysis to determine stress levels of a loaded square drive adapter. Excessive stress concentration is noticed at a point where actual crack initiated. Optimized design is proposed, capable of handling declared torque. FE stress analysis of optimized square adapter revealed acceptable stress levels and shifting of stress concentration point further along the adapter. Conclusion is that the manufacturer needs to reconsider actual design in order to avoid future failures.

Torque wrench adapter ; Failure analysis ; Failure ; Fracture ; Crack

nije evidentirano