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With the amount of adjustability present in today's automotive seat, it is a given that some form of looseness and free-play will exist in the structure. The automotive seat community is commonly faced with free-play issues; this is a significant issue where modal analysis is concerned. Free-play creates a non-linear situation, causing a violation of the linear mathematics that modal analysis is based on. Obviously, this situation is not the ideal circumstances under which to perform modal testing and analysis, but 99.9% of the time, the receipt of better samples (reduced free-play) is not a likely option, and the test must still go on. Ideally, you would want to test this structure using random excitation with a shaker to minimize the nonlinearities and provide a repeatable input force.

Measuring and modeling parasitic losses in driveline components continues to be an important topic in product development. There are existing standards (SAE J2985 [1], J3039[2], and J3218[3]) for measuring and reporting spin loss parasitic losses. All these tests are conducted at fixed temperatures of 28°C and 65°C with a variety of controls and measurement positions to ensure these conditions. The limitation of these methods is that they do not represent the actual vehicle range of operating temperatures. In 2020, Guarino et al presented the paper SAE 2020-01-1413 [4] on development of a test method for beam axles (which was developed into SAE J3218). In the paper, a floating temperature sweep test method was developed for testing efficiency over a range of temperature at a fixed operating condition. This paper will highlight adapting the efficiency floating temperature sweep test method and applying it to spin loss measurement (a transfer case was used in this development).