Abstract
<div class="section abstract"><div class="htmlview paragraph">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 comfort performances.</div><div class="htmlview paragraph">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.</div><div class="htmlview paragraph">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 allowing quick and effective criteria of estimating damage.</div><div class="htmlview paragraph">The first case study 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. The main criterion is the consideration that the local damage at the failure zone can be derived from the absolute displacement of the item under test.</div><div class="htmlview paragraph">The second case involved air conditioning system blowers. Based on physics-of-failure criteria, we demonstrate that vibration endurance tests requested by carmakers are not representative of real environments and resulting test failures are not realistic. A more representative profile is then proposed for durability tests.</div></div>