Simulating Squeak & Rattle Phenomena in a Truck Cabin

Squeak and rattle phenomena are studied in the automotive industry in an attempt to reduce the cabin noise and as a result, give a better ride quality and comfort to occupants. In the case of Scania’s Cabin Development Department, this kind of simulation was not performed historically. The team had to rely on tolerance calculations as well as the choice of materials to reduce the risk of squeak and rattle. To reduce development time and cut down on iterative changes, a desirable solution was identified that enabled a simulation-driven design process during the early stages of the cabin development cycle.

Jan Söderlund, Head of Instrument Panel Development, selected LeanNova Engineering AB and Altair ProductDesign as partners to assist with the development process for a Scania truck cabin. Altair ProductDesign presented the squeak and rattle simulation methodology. The first step involved modal correlation of the plastic parts from an existing cockpit in order to improve the material database for future simulations. The second step was to build up a full vehicle model for various types of cabin, and by applying loads from road test measurements, calculate the relative displacement at defined interfaces.

All of this work was conducted using Altair’s Squeak and Rattle Director (SNRD), which empowers engineers to perform more simulations by reducing the time needed for analysis of squeak and rattle phenomena.

Using many calculation loops and continuous calculation iterations, the focus was to improve the performance for each system and then study the interfaces between these different systems. The output from SNRD delivered valuable input for the designers to help find better attachments and boundary conditions to their parts. In addition, the tolerance analyst benefits from the dynamic tolerance calculated in SNRD to include in the static tolerance calculation.

“Altair's Squeak and Rattle Director has helped the Cabin Development Department to focus on the risk areas and make improvements very early in the design process, enabling consciousness of these issues at an early stage without hardware, and creating value to the end customer.”
Jan Söderlund, Head Instrument Panel, Driver Control Unit and Climate System, Scania CV AB