Fast Iterative Design Optimization for Reliability Vibration Tests in Automotive

The development of an engine-cooling module (ECM) for an European carmaker faced a major blocking point. The stalemate concerned the design of the suspension rubbers separating the engine-cooling radiator (the ECM carrier) from the chassis. The development of an engine-cooling module (ECM) for an European carmaker faced a major blocking point. The stalemate concerned the design of the suspension rubbers separating the engine-cooling radiator (the ECM carrier) from the chassis. From the one hand, the damping rubbers had to be soft, in order to be compliant with noise, vibration & harshness (NVH) criteria - acoustic noise and vibration transmitted to the cabin. On the other hand, their softness would provoke such high amplitude response during shaker tests that the module carrier (the radiator) would fail at the early stage of vibration testing - a leakage was observed after 10 hours of the targeted 90 hours duration. New rubbers, designed for durability purposes, would fail to meet the NVH criteria. The project development team went through a double-faced dilemma: how to design rubbers with an acceptable trade-off between NVH and durability of the engine-cooling radiator, and how to find a quick and efficient way to validate the design in order to be compliant with vibration validation tests. Together with the customer, our company (automotive tier-1 supplier) established an iterative design optimization of the damping rubbers, based on the simultaneous feedback from the acoustic response and the durability predictions. The goal was to develop a strategy permitting a quick an effective criteria for damage estimation for each design proposed.