Acoustic VS reliability. Case study of automotive components undergoing vibration endurance tests 2024-01-2948

During design development phases, automotive components undergo a strict validation process aiming to demonstrate requested levels of performance and durability. In some cases, specific developments encounter a major blocking point : decoupling systems responsible for optimal acoustic performances. On the one hand, damping rubbers need to be soft to comply with noise, vibration & harshness criteria. However, softness would provoke such high amplitudes during vibration endurance tests that components would suffer from failures. On the other hand, stiffer rubbers, designed for durability purposes, would fail to meet noise compliance. The rubber design development goes through a double-faced dilemma : design with acceptable trade-off between NVH and durability, and efficient ways to develop compliant designs. This paper illustrates two case studies where different methodologies are applied to validate decoupling systems from both acoustic and reliability perspectives. The goal was to develop a strategy permitting quick and effective criteria of damage estimation. The first case involved HVAC blowers. Based on physics-of-failure criteria, we demonstrate that vibration endurance tests requested by carmakers are not representative of real environments and resulting failures are not realistic. A more representative profile is then proposed for durability tests. The second case describes a new methodology, based on vibration measurements, reliability prediction and the simultaneous acoustic feedback, that helped establish an iterative design optimization of engine cooling module dampers. Finally we illustrated the state of the art concepts related to the design validation process digitalization in the framework of a modern environment approach design.