Synergic computational and experimental development of a cast iron crankshaft for high performance automotive diesel engine

In order to achieve consistent cost reduction, an extensive and simultaneous experimental and computational activity has been performed within GM Powertrain Europe (GMPT-E) with the aim of substituting a steel crankshaft with a cast iron one in a high performance automotive diesel engine, as described in this paper. By means of a preliminary simulation analysis the most critical sections of the crankshaft have been identified andsubsequently strain-gauges have been installed in such locations on a prototype crankshaft. This latter has been then installed on a firing engine in order to provide bending and torsion stresses on the selected points, so to correlate the crankshaft mathematical model outputs with actual results. The following step has been to run a more detailed simulation, by using the calibrated finite element model of the crankshaft, in the framework of a multi-body analysis, with the aim of assessing the crankshaft fatigue behaviour. A key feature of the above described approach is the ability to set-up a reliable mathematical model to be extensively applied for Virtual Validation, by means of DOE (Design Of Experiment), FLP (Fatigue Life Prediction) and DFSS (Design For Six Sigma) approaches, aimed at assuring a final robust design of the crankshaft. The activities described above, together with GM standard components reliability verification, demonstrated the feasibility of this cost reduction initiative and provided a powerful design and validation technique in the framework of the ongoing migration from "road to rig to math".