Volume 40, Issue 4 (July 2012)
Measurement of Creep-induced Change of Dynamic Stiffness of Resilient Materials Used for Impact Sound Isolation in Floating Floors
The creep-induced change of the dynamic stiffness of resilient materials used in vibration isolation systems in floating floors is an important issue, especially with regard to the use of open cell resilient materials, because the change in the dynamic stiffness is a key factor in the performance of vibration isolators, and open cell materials are vulnerable to creep deformation. This study proposes a method for measuring the creep-induced change of the dynamic stiffness that employs quasi-static mechanical analysis under the assumption that the creep-induced change of the mechanical structure of the resilient material is independent of time and stress. The pre-creep dynamic properties of a sample resilient layer measured with a method very similar to the one recommended in ISO 9052–1 are compared with the data measured with the proposed method, and the results illustrate the consistency in the data measured with the two methods. A proposed creep test is performed for a sample resilient layer including open cell material used for a floating floor, and the change in the dynamic stiffness due to creep deformation is assessed by combining the proposed method and the creep test data. The study indicates that the proposed method is able to assess the creep-induced change of the dynamic stiffness and could be useful for the design of vibration isolation systems in long-term use.