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NVH (Noise Vibration & Harshness) is one of the main focus areas during the development of products such as passenger cars or trucks. Physical test methods have traditionally been used to assess NVH, but the necessity for reducing cost and creating a robust solution early in the design process has driven the increased usage of simulation tools. Development of well-defined methods and tools for NVH analysis allows today’s OEMs to have a virtual engineering based development cycle from concept to test. However, a subset of NVH problems including squeak and rattle (S&R) have not been generally focused upon. In a vehicle, S&R is a recurring problem for interior plastic parts such as an instrument panel or door trim. Since 2012, Altair has been developing S&R Director (SnRD), which is a solution that identifies and combats S&R issues by embedding the Evaluation-Line (E-Line) methodology [1] [2].

A new Squeak & Rattle simulation method was presented at the ISNVH conference 2010 (SAE 201-01-1423). This method, called the SAR-LINE™ method, is based on the evaluation of the relative displacement in time domain due to a random load. A specific challenge for a Squeak & Rattle simulation approach is to correlate the results to a real squeak or rattle phenomenon. This paper presents a new test procedure which enables the correlation between the results of the SAR-LINE™ simulation and the audible rattle occurrence. Three different configurations with increasing complexity were both tested and simulated. A pseudo random signal was used as load and the relative displacement was measured with the Laser Scanning Vibrometer in time domain. The movement in the gap and the rattle sound were recorded in a video sequence. The simulated results along the SAR line can directly be compared with the measured results along the gap.

To achieve “right first time” design for SAAB projects, thus avoiding unnecessary development loops, a squeak & rattle simulation tool was required. This paper presents a new squeak & rattle simulation approach which covers the complete development process of interior parts. The process starts with a rough model, which is mainly based on styling data and ends with a model of a very high detail level close to serial tooling status. The detailed CAD model is then represented by a simulation model of similarly increasing quality. By using different types of analyses in the frequency and time domains (modal analysis, frequency response and transient analysis), the output of these simulations can be matched to the available FE model quality. During initial development the global behavior of the structure is of interest. Finally the relative displacement between two detailed trim parts is used to evaluate the risk for squeak & rattle.