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As part of the update process to SAE J1637, Laboratory Measurement of the Composite Vibration Damping Properties of Materials on a Supporting Steel Bar, the Acoustical Materials Committee commissioned a round robin study to determine the current laboratory-to-laboratory variation, and to better understand best practices for composite loss factor measurements. Guidance within the current standard from a previous round robin study indicates a coefficient of variation of 35% for laboratory-to-laboratory measurements. It was hoped that current instrumentation and test practices would yield lower variability. Over the course of 2 years, 8 laboratories tested 4 bars, three damped steel bars and one bare steel bar. These bars were tested at -20°C, -5°C, 10°C, 25°C, 40°C, and 55°C. The damping materials were intentionally selected to provide low damping, moderate damping, and high damping as difficulties in determining the composite loss increase with increased damping.

As part of the update process to SAE J1637, “Laboratory Measurement of the Composite Vibration Damping Properties of Materials on a Supporting Steel Bar”, the Acoustical Materials Committee commissioned a round robin study to determine the current laboratory-to-laboratory variation, and to better understand best practices for composite loss factor measurements. Guidance within the current standard from a previous round robin study indicates a coefficient of variation of 35% for laboratory-to-laboratory measurements. It was hoped that current instrumentation and test practices would yield lower variability. Over the course of 5 years, 10 separate laboratories tested 4 bars: three damped steel bars and one bare steel bar. The bars were tested at -20°C, -5°C, 10°C, 25°C, 40°C, and 55°C. The damping materials were intentionally selected to provide low damping, moderate damping, and high damping to illustrate difficulties in determining the composite loss factor with increased damping.