<title>Passive and active launch vibration studies in the LVIS program</title>

Abstract

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Influence of flexible interface on the performance of whole spacecraft vibration isolation

“…This may considerably decrease the performance of a vibration isolation device. In some applications, some rotation constraint devices are added into the vibration isolation devices (Edberg et al, 1998;Liu et al, 2005). The inherent flexibility of the interface structure may also degrade the function of such devices.…”

“…In such cases, the single degree of freedom model is the most widely used approach to represent a vibration isolation system. However, there are other cases in which the interface should be considered as a flexible structure, such as the vibration isolation platform (VIP) developed in Edberg et al (1998) for improving the dynamic environment of a spacecraft, which is composed of several isolators assembled together to provide multi-axial vibration isolation to the spacecraft. For limiting the weight added and saving the space occupied, especially for the whole spacecraft vibration isolation, the stiffness of the interface structure cannot be made sufficiently high, and also that of the interface of the isolated structure.…”

“…For limiting the weight added and saving the space occupied, especially for the whole spacecraft vibration isolation, the stiffness of the interface structure cannot be made sufficiently high, and also that of the interface of the isolated structure. Numerous publications have studied and discussed the modeling of the vibration isolation devices (Edberg et al, 1998;Liu et al, 2005). Typically, the interface of the VIP is assumed to be rigid.…”

“…A spacecraft usually has a cone-shaped thin shell adaptor for the connection to the launch-vehicle, under which is the VIP's interface with flange on which the isolators are installed at circumferentially distributed points by joints such as spherical hinges and bracket assemblies whose dimensions are relatively small in comparison to the diameter of the interface flange. The VIP provides support to the spacecraft adaptor at these connection points (eight points in OVIP in Edberg et al (1998)). Because of the flexibility of the interface structure, there are flexible motions in all directions and some typical flexible motions are shown in Figures 1 and 2, which are inphase motion and petal-like motion.…”