Abstract

In turbocharger, there is possibility that the impeller may sometimes burst at high rotating speed due to high centrifugal forces and temperature conditions at such high speed. The occurrence of such type of failure is very less but the risk in high. Therefore, to ensure safety of end customer, a turbocharger goes through multiple tests, out of which one is containment test. In this test, the wheel is burst by rotating it beyond the maximum operating speed. In this condition, the compressor housing should be able to contain these wheel fragments within the housing. But in test data of midrange turbocharger failed in burst and containment test, one of the causes of test failure was failure of bolted joint between compressor housing and bearing housing. Hence re-designing of the bolted joint is seen as a possible method to help in compressor cover retention. These re-designed bolted joints are termed as non-axial bolted joint.

As wheel burst is time dependent impact event, explicit dynamic analysis is carried out for simulating that event. The objective is to observe effect of re-designed bolted joint in terms of stress results in explicit analysis. This paper presents a new methodology developed for explicit dynamic analysis of structure with bolted joint. The methodology is for applying bolt pretension for performing explicit analysis. Analysis on proposed model was carried out as turbocharger assembly takes large computational time. The explicit analysis results of proposed models are compared by DOE tool.

Keywords:Containment test; Impeller burst; Bolted joint