CAE Techniques for System Analysis of Hypoid Gearset Vibration 2011-01-1502

Traditionally, the development of automotive drivelines incorporating hypoid or spiral bevel gearing using Computer Aided Engineering (CAE) methods have included the analysis of gear contact patterns independent of the influence of the flexible members of the driveline such as the housing and shafting. The gear tooth form development typically occurs using various non-linear gear contact solutions available on the market, but the final refinement of the gear itself usually must wait until the actual hardware can be fabricated and tested in the driveline system. This behavior may result in several costly and time consuming iterations of testing, modifying, and re-testing a gearset, since the up-front CAE tools did not account for the flexibility of the driveline system, nor factors such as bearing pre-load effects, thermal growth, driveline torque levels, dynamic modes of the shafting, and many other important factors. While, in the past, finite element tools have addressed the system response sensitivity to unit transmission error excitation for analysis of the noise and vibration performance, this method has not been coupled with the non-linear gear contact as part of the analysis for prediction of absolute vibration levels of the housing, accurately accounting for bearing stiffness due to load, for instance. Using a strategic software interface, an advanced CAE tool was recently developed allowing predictions of hypoid gearset contact patterns and absolute vibration performance, as well as gear and bearing durability ratings, to be evaluated factoring in the aforementioned driveline system effects. An additional interface allows the same model to be evaluated using a non-linear, time-varying software tool developed by a major university. The complete CAE solution will be examined in detail, using real world hardware for comparative purposes.