On the uncertainty of measurement of dynamic stiffness of resilient materials

• Published in: The Journal of the Acoustical Society of America 2017-05, Vol.141 (5), p.3930-3930
• Main Author: Larsson, Krister
• Format: Article
• Language: English
• ISSN: 0001-4966; 1520-8524
• DOI: 10.1121/1.4988890

The apparent dynamic stiffness of resilient materials used for example under floating floors is measured according to the standard ISO 9052-1:1989 (EN 29052-1:1992). Basically, the material under test is loaded by a load plate corresponding to 200 kg/m2 and the resonance frequency of the first vertical mode of the mass-spring system formed by the load plate and the resilient material under test is determined. The resonance frequency then gives the dynamic stiffness. The standard allows for several excitation techniques such as swept sine, continuous noise, or impact excitation. Additionally, vibration excitation at the base as well as force excitation on the load plate is allowed. In this study, the uncertainty because of excitation of multiple vibration modes is investigated in detail. A model for the load plate on an elastic foundation representing the test setup is developed. The model is verified towards measurements and a parameter study is performed. The results show that additional modes may be excited depending on the excitation, which might lead to erroneous results. Suggestions for procedures to take the excitation of multiple modes into account and to improve the uncertainty of the method are given based on the findings.