Recommended Practice Provides Test Procedure to Measure Composite Loss Factor and Bending Stiffness Properties
WARRENDALE, Pa. (Jan. 19, 2024) – SAE International’s Acoustical Materials Committee (AMC) recently released SAE J3130: Laboratory Measurement of Vibration Damping Properties Using Mechanical Impedance Method at the Center of a Bar. This recommended practice provides a test procedure to measure the composite loss factor and bending stiffness properties of a system consisting of a damping material bonded to a vibrating bar which is excited at the center.
This new test is a gamechanger for noise and vibration professionals, and as described by noise and vibration expert and AMC member Pranab Saha, Ph.D., P.E., “very critical for lightweighting body panels.”
“These test methods are not covered by ASTM, ISO, or JIS standards, which are designed more for architectural, commercial, and industrial applications,” Dr. Saha said. “This is the main reason why the AMC developed this standard.”
As manufacturers focus on making lighter vehicles, understanding how different materials perform is a growing concern for industry. The AMC surveyed resources available to engineers for sound package material testing and uncovered a crucial need for a more specific testing procedure unique to the new materials being used for the center bar.
“With the effort toward lightweighting of vehicles, car body panels are changing from steel to aluminum and even non-metallic composite materials,” Dr. Saha said. “SAE J3130 allows one to test any bar: steel, aluminum, glass, composites, and many other kinds.”
According to Dr. Saha, the previous way to measure damping was the Oberst bar test method—first introduced in SAE J1637 in 1993. However, J1637 is applicable only for steel bars. Even there, if the steel bar is very thick, as it is in off-highway vehicles including construction vehicles and harvester vehicles, the J1637 does not work but the J3130 does. Dr. Saha also mentioned that there are two other standards with similar methodology to J3130 (JIS G 0602: Vibration-damping property and ISO 16940: Glass in Building) but noted that their applications are limited to testing steel bars and glass bars, respectively.
The J3130 standard is available here: https://www.sae.org/standards/content/j3130_202312/. To learn more about the Acoustical Materials Committee, visit: https://standardsworks.sae.org/standards-committees/acoustical-materials-committee
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