Vehicle quality has become one of the most important factors in customer satisfaction. Of all quality attributes, noise, vibration, and harshness (NVH) are often immediately noticed by customers during purchase trial drives or initial usage periods. High-quality NVH is, however, one of the most challenging attributes to achieve. Vehicle development constraints usually require that other attributes such as safety, durability, functionality, package, weight, and cost be satisfied prior to NVH attributes. Laser metrology has advantages including spatially dense data points and the fact that it is non-contact, non-invasive, and fast. It has become an indispensable tool to provide optimal solutions for achieving high-quality NVH under various constraints. This article focuses on the state of the art and its applications on reducing NVH and related concerns in the automotive industry.
Keywords: laser metrology, noise and vibration, automotive
INTRODUCTIONis converted to vibratory energy of the brake components, the brake system will vibrate and generate In today's highly competitive automotive market, brake roughness/judder or noise. Brake roughness is customers have high expectations concerning vehicle a low-frequency vibration caused by brake torque quality. Of all quality attributes, noise, vibration, and variation (BTV) at the wheel/brake assembly during harshness (NVH) are often immediately noticed by braking and propagated through the suspension customers during purchase trial drives or in initial and steering. One of the root causes of BTV is purchase usage periods. NVH is one of the items disc/rotor thickness variation (DTV). The challenge shown in JD Power Associates' initial quality survey.is quickly and accurately to obtain a rotor surface Vehicle development constraints usually require that profile with spatially dense data points when the other attributes such as safety, durability, functionrotor manufacturing process capability is being ality, package, weight, and cost be satisfied prior verified. Laser metrology can be used to achieve this to NVH attributes, which makes high-quality NVH goal. Brake noise mainly includes groan, moan, and one of the most challenging attributes to achieve. squeal, with squeal being the most often occurring Of all NVH issues, three of the major sources are noise. Brake squeal is a high-frequency noise and is the noise and vibration from the engine/powertrain generally caused by friction-induced self-vibration system, brake/suspension system, and body panels.[1, 2]. Computer aided engineering (CAE) using a The following examples are taken from vehicle finite element model to simulate brake noise has development/problem solving projects.been greatly advanced recently [3]. However, before Brakes stop vehicles by transforming vehicle kinetic the CAE model can provide a design optimization energy to other forms of energy, such as thermal solution, the model firstly needs to be correlated. energy. However, when some of the kinetic energy One of the correlation and squeal root caus...
