Recent advances in brake noise and vibration engineering using laser metrology

Noise, vibration, and harshness (NVH) can be predominate brake noise described as roughness/judder, brake creep groan, and brake squeal, all of which are important issues and concerns for customer satisfaction in the automotive industry. Brake roughness and groan are low-frequency vibration and noise, while brake squeal is a high-frequency noise. These have been the challenging issues for engineers and researchers for many years due to their complex nature that involves multiple disciplines such as nonlinear dynamics, contact mechanics, and tribology or nanotribology. As in the body/chassis and power-train arena, laser metrology can be uniquely applied in brake NVH to shed light on this complex issue. Engineers can gain insight on NVH fundamental root causes and provide guidance for optimal design resolution. We provide some examples that illustrate the recent progress and novel applications of holographic interferometry, pulsed laser holographic interferometry, pulsed laser electronic speckle pattern interferometry, and laser Doppler vibrometry methodology to identify the root causes of brake concerns and verify engineering solutions.