SAR Line Methodâ„¢ - A new method for Squeak & Rattle simulation and test developed at SAAB

To achieve “right first time” design for SAAB projects, thus avoiding unnecessary development loops, a squeak & rattle simulation tool has been developed.

A new squeak & rattle simulation approach is presented 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 close to serial tooling status. The detailed CAD model is then represented by a simulation model of similarly increasing quality. By using the SAR line method the local gap and contact geometry is represented in a way which enables the post processing of the relative displacement due to a random signal in the time domain.

During initial development the global behavior of the structure is of interest. Finally the relative displacement between two detailed trim parts along the SAR line is used to evaluate the risk for squeak & rattle with a statistical approach.

In order to identify the capability of the squeak & rattle simulation different correlation work between test and simulation has been performed. Examples of modal correlation on a global and local level of the interior assemblies are shown. Also a procedure which enables the correlation between the tested (with laser scanning vibrometer) and simulated relative displacement due to a random load is presented.

This new squeak & rattle simulation has been used during the development of the new SAAB 9-5. Different examples of how the simulation results supported and guided the cockpit design clearly justify the benefits of this approach. The method was presented in a SAE paper (SAE 2010-01-1423) at the ISNVH conference in Graz 2010 and won the Best Paper Award.

The Author

Jens Weber Ismail Benhayoun
CAE-Development Engineer CAE-Development Engineer
Interior & Interior Safety Interior & Interior Safety
Saab Automobile AB Saab Automobile AB

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