| Popis: |
With the emphasis in lightweighting of vehicle body structures, body panel vibration and structure-borne noise are big concerns to sound package engineers. Damping materials are used to mitigate these issues. As aluminum and different composite materials are used to make lightweight vehicle body panels, a damped panel using these materials cannot be used in Oberst bar damping tests which uses a non-contacting transducer. To address this situation, SAE's Acoustical Materials Committee is developing a new damping standard (SAE J3130) based on the mechanical impedance measurement method, also called the CenterPoint method. The committee is currently conducting a round robin study that includes different types of damping materials and different types of vibrating bars, including steel, aluminum, and glass bars. This paper discusses the status of the round robin testing. It emphasizes the importance of data analysis using h statistic and k statistic, where h statistic checks the difference between means and k statistic checks the difference between variances. The paper illustrates some case studies based on the work done so far. |
