Squeak and Rattle Prediction for Robust Product Development

Licentiate thesis, 2020

Squeak and rattle are nonstationary, irregular and impulsive sounds that happen inside the car cabin. For decades, customer complaints about squeak and rattle have been, and still are, among the top quality issues in the automotive industry. These annoying sounds are perceived as quality defect indications and burden warranty costs to the car manufacturers. Today, the quality improvements regarding the persistent type of sounds in the car, as well as the increasing popularity of electric engines, as green and quiet propulsion solutions, stress the necessity for suppressing annoying sounds like squeak and rattle more than in the past. The technical solution to this problem is to approach it in the pre-design-freeze phases of the product development and by employing design-concept-related practises. To nail this goal, prediction and evaluation tools and methods are needed to deal with the squeak and rattle quality issues upfront in the product development process.

The available tools and methods for prediction of squeak and rattle sounds in the pre-design-freeze phase in a new car development process are not yet sufficiently mature. The existing knowledge gap about the mechanisms behind the squeak and rattle sounds, the lack of accurate simulation and post-processing methods, as well as the computational cost of complex simulations are some of the significant hurdles in this immaturity. This research addresses this problem by identifying a framework for prediction of squeak and rattle sounds in the form of a cause and effect diagram. The main domains and the elements and the sub-contributors to the problem in each domain within this framework are determined through literature studies, field explorations and the conducted descriptive studies on the subject. Further, improvement suggestions for the squeak and rattle evaluation and prediction methods are proposed through prescriptive studies. The applications of some of the proposed methods in the automotive industry are shown and examined in industrial problems.