openHSU – Research Showcase

Shockmounts are widely used to isolate sensitive equipment from vibrations and mechanical shock. Despite the highly dynamic nature of shock events, the force-displacement-characteristics of shockmounts which are provided by manufacturers are gained by static measurements. Therefore, this paper presents a dynamic mechanical model of a setup for dynamic measurements of force-displacement-characteristics. The model bases on acceleration measurement of an inert loading mass, which displaces the shockmount, when the arrangement gets excited by means of a shock test machine. The influence of the shockmount’s mass in measuring setup is considered as well as special needs for handling measurements under shear or roll loading. A method for allocating the measured force data on the displacement axis is developed. An equivalent of a hysteresis-loop in a decaying force-displacement-diagram is proposed. Based on exemplary measurements, error calculation and statistical analysis show the qualification of the proposed method for attaining dynamic FDC.

Shockmounts in naval applications are used to mount technical equipment onto the structure of naval vessels. The insulating effect against mechanical shock is important here, as it can excite the structure in the event of underwater explosions and otherwise cause damage to the equipment. Although knowledge of the dynamic properties of shockmounts is important to naval architects, the dynamic force-displacement characteristics of shockmounts are often tested and measured statically and/or in the harmonic field. Recently, an inertia-based method and a dynamic model for measuring the dynamic force-displacement characteristics of shockmounts was described. This paper presents a full description of a testbench for implementing this method. The testbench incorporates a drop table for excitation. The proposed setup can be configured for measuring the dynamic characteristics of elastomer and wire rope shockmounts, with shock loads in compression, tension, shear and roll directions. The advanced Kelvin–Voigt model for shockmounts is applied, showing that the dynamic force-displacement characteristics measured with this setup are qualified to generate model parameters for further use.