Due to recent advancements in interior noise level and the excessive use of different grade leathers and plastics in automotive interiors, squeak noise is one of the top customer complaints. Squeak is caused by friction induced vibration due to material incompatibility. To improve costumer perception, interior designs are following zero gap philosophy with little control on tolerances leading to squeak issues. Often manufacturers are left with costly passive treatments like coatings and felts. The best option is to select a compatible material with color and finish; however, this will reduce the design freedom.
Material compatibility or stick-slip behavior can be analyzed with a tribology test stand. However, this test is performed on a specimen rather than actual geometry. There were instances, when a material pair was found incompatible when tested on a specimen, but never showed any issue in actual part and vice versa. Thus, interface stiffness and system sensitivity between the parts are important while analyzing the stick-slip behavior before implementing any solutions.
To improve the process vehicle interiors are analyzed by CAE methods to evaluate stick-slip behavior by utilizing SSP test data. The CAE methodology considers wide range of input load cases, global and local system sensitivity, local geometries, and connection stiffness to get realistic results from squeak simulations, which otherwise not possible with stick-slip testing. In the present study, “no relative movement no squeak” philosophy is used to drive the design of interior trims to avoid squeaks. Squeak risk at interface is evaluated by comparing in-plane relative displacement with ‘1/ IRmax’ value obtained from stick-slip testing. Meaningful information has been extracted through linear static analysis to understand the influence of preloading on contact forces between the interfaces. This approach has improved the squeak prevention process in product development without changing materials or usage of passive treatments.