Search Results

Today vehicle owners perceive squeaks and itches inside a vehicle cabin as a major negative indicator of vehicle build quality and durability. Manufacturers struggle to bear the high costs of squeak and rattle (S&R) related warranty. Although the benefits of structural integrity and tight manufacturing tolerances with respect to the prevention of S&R are known, today's cost, weight, crash requirements, aesthetic demands and environmental/fire hazard rules quite often dictate the design of S&R prone sub-systems. Even sub-systems with the best possible structural design and manufacturing tolerances are not immune to extreme environmental conditions, and mating materials can initiate contact leading to S&R. One method of minimizing the possibility of squeaks is by the judicious selection of mating material pairs. This paper describes a test process aimed at the quantification of material pair compatibility.

Over the past five years, the US Automotive Materials Partnership (USAMP) has brought together representatives from DaimlerChrysler, General Motors, Ford Motor Company and over 40 other participant companies from the Mg casting industry to create and test a low-cost, Mg-alloy engine that would achieve a 15 - 20 % Mg component weight savings with no compromise in performance or durability. The block, oil pan, and front cover were redesigned to take advantage of the properties of both high-pressure die cast (HPDC) and sand cast Mg creep- resistant alloys. This paper describes the alloy selection process and the casting and testing of these new Mg-variant components. This paper will also examine the lessons learned and implications of this pre-competitive technology for future applications.

The laboratory test method commonly known as “random vibration” is almost always used for Squeak & Rattle testing in today's automotive applications due to its obvious advantages: the convenience in simulating the real road input, the relatively low cost, and efficiency in obtaining the desired test results. Typically, Loudness N10 is used to evaluate the Squeak & Rattle (S&R) performance. However, due to the nature of random distribution of the excitation input, the repeatability of the loudness N10 measurements may vary significantly. This variation imposes a significant challenge when one is searching for a fine design improvement solution in minimizing S&R noise, such as a six-sigma study. This study intends to investigate (1) the range of the variations of random vibration control method as an excitation input with a given PSD, (2) the possibility of using an alternate control method (“time-history replication”) to produce the vibration of a given PSD for a S&R evaluation.

The authors participated in a task force that was required to develop a repeatable, dependable, and reliable test procedure to compare, rate, and evaluate the severity of rattles. The assemblies involved in the study are designed and manufactured by different companies and are tested by different people on test equipment and instrumentation from different suppliers. The challenges therefore, were considerable and involved both the vibration inputs and responses as well as the acoustic responses. At the beginning of this activity, it was observed that different test labs using the same Ford vibration specs were obtaining different sounds from the same test item! Clearly, this was unacceptable and the test methods had to be improved and standardized. This paper focuses on vibration related to rattle testing. The particular assemblies used in this study were seat belt retractors.