The Thought and Reasoning Behind Developing SAE J1637 - Vibration Damping Test Method 931320
The paper discusses the importance of a well documented standardized laboratory test procedure to evaluate damping material performance for the automotive industry, and to understand the parameters that influence the precision of the test method. The standard outlines a methodology which was developed with the general consensus of automotive engineers, suppliers, and independent test laboratories. The methodology is based on the Oberst bar test method where a damping material is bonded to a specific size steel bar and the system is excited at its various modes of vibration under a cantilevered configuration. The damping performance is expressed in terms of composite loss factor, ηc, within the frequency range of approximately 100 Hz to 1000 Hz, and over the useful range of temperatures for the given application. The paper reviews the results of round-robin tests that were conducted at ten different laboratories, and discusses various precautions that need to be taken to obtain valid data. The paper also discusses the variability of the round-robin test results within a laboratory (repeatability) as well as that of between laboratories (reproducibility). Finally, the paper discusses ways to evaluate the consistency of the data and to detect unusual values which affect the precision of the test method.