A Modification of an Estimation Method of the Natural Frequency of a Cube Form Micro Satellite

Abstract

Micro satellites must survive severe mechanical conditions during their launch phase. One design requirement for rockets is the stiffness requirement, i.e. the natural frequencies requirement. In the early stages of satellite development, presumption of the natural frequency of a satellite may be difficult.
 The material used for the structure of many micro satellites is an aluminum alloy. The structure subsystem occupies a large portion of the satellite mass, and the elastic modulus of this aluminum alloy is larger than that of other subsystems. Therefore, the mechanical property of the aluminum alloy cannot be used to represent the mechanical property of the whole satellite. The density of an actual satellite differs from the density of the aluminum alloy. Therefore, when estimating the minimum natural frequency, the size and the elastic modules of an actual satellite structure must be used. When using an actual satellite structure, the estimated minimum natural frequencies of the lateral direction and the longitudinal direction during the ascent phase are in agreement with the measured values acquired by the vibration tests.
 In order to shorten a process of satellite development, this paper describes a practical method for estimating the natural frequency of a cube-shaped micro satellite
 This paper is a modified version of the previous paper [1] using new measurement results.

A Simple Method for Identifying the Natural Frequency of a Micro Satellite with a Primary Structure made of Aluminum Alloy

“…A satellite with which the fitting is carried out in a rocket is expressed in Figure 1 [2]. This is called a single-degree-of-freedom system (SDOF system).…”

“…These forms were cubes mostly and the lengths of one side ranged from approximately 50 cm. The specifications of the micro satellites used for this testing are shown in Table 2 [2]. Each micro satellite was vibrated in the Launch direction (longitudinal direction), and the minimum natural frequencies for each were measured.…”

“…This is the n value used to calculate the deflection when a bending moment load is applied to the free end of a fixedly supported cantilever beam. Okuyama et al obtained the minimum natural frequencies in the lateral direction of five cubeshaped micro satellites through vibration tests as well as in the longitudinal direction [2]. Table 3 shows the calculated values of the minimum natural frequency obtained by inputting 3 as the n value in Eq.…”

Structural Responses of a Conceptual Microsatellite Structure Incorporating Perforation Patterns to Dynamic Launch Loads

“…As a result, these loads will be disregarded in the current work, and will not be mentioned again. Previous works that considered dynamic launch loads included Aborehab et al [40], Oh et al [41], Cote et al [42], Okuyama et al [43], Park et al [44], and others.…”