Failure Mode Effect and Criticality Analysis of Stub Axle Subassembly

991 Words Sep 11th, 2013 4 Pages
Failure Mode Effect and Criticality Analysis of
Stub axle subassembly

1. Introduction: FMECA is a methodology to identify and analyse predicted failure modes of various parts within the assembly or system. It is a technique to resolve potential problems in a system before they occur. It is most widely used reliability analysis technique performed between the conceptual and initial stage of the detailed design phase of the system in order to assure that all the potential failures have been considered and the proper provisions have been made to eliminate these failures. [1] (Ref. system reliability theory,2nd edition, Marvin Rausand) this technique can assist in selecting alternative concept for the same system and also provide
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iii. Steering arm: The steering arm may fail from two places: one is from weld joint with the assembly and another is the swivel join on the far end where it is connected with the steering rod. But the probability of failure of swivel joint is higher because it repetitively undergoes excessive wear as vehicle takes turning (cornering), the steering arm of the inner wheel moves in two planes as shown in diagram 3 below facing excessive wear.

The other probability of failure of that joint is shear failure of either bolt or steering rod tip as mentioned in diagram 4 above. The failure effect of the system due to weld failure is severe, as system cease working and is a high safety impact.

iv. Rod end bearing: The main function of this component is to provide support of whole subassembly through HTS bolt. It has to bear all the impact load imparted by the stub axle through bolt. So sufficiently tough enough to withstand such load. So the probability of failure is crushing of bush or shearing off bolt as shown in force body diagram 5 below. The effect of such failure on the system is severe having high safety impact.

4. FMECA worksheet: On the basis of the discussion above about each part’s functions, expected caused of failure and its effect on the system, it would now be ease to make FMECA

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