Modal Analysis of Conceptual Microsatellite Design Employing Perforated Structural Components for Mass Reduction

Sarmad Dawood Salman Dawood,Ahmad Salahuddin Mohd Harithuddin,Mohammad Yazdi Harmin

doi:10.3390/aerospace9010023

Sarmad Dawood Salman Dawood, Ahmad Salahuddin Mohd Harithuddin + Show 1 more

Open Access

https://doi.org/10.3390/aerospace9010023

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Abstract

Mass reduction is a primary design goal pursued in satellite structural design, since the launch cost is proportional to their total mass. The most common mass reduction method currently employed is to introduce honeycomb structures, with space qualified composite materials as facing materials, into the structural design, especially for satellites with larger masses. However, efficient implementation of these materials requires significant expertise in their design, analysis, and fabrication processes; moreover, the material procurement costs are high, therefore increasing the overall program costs. Thus, the current work proposes a low-cost alternative approach through the design and implementation of geometrically-shaped, parametrically-defined metal perforation patterns, fabricated by standard processes. These patterns included four geometric shapes (diamonds, hexagons, squares, and triangles) implemented onto several components of a structural design for a conceptual satellite, with a parametric design space defined by two scale factors and also two aspect ratio variations. The change in the structure’s fundamental natural frequency, as a result of implementing each pattern shape and parameter variation, was the selection criterion, due to its importance during the launcher selection process. The best pattern from among the four alternatives was then selected, after having validated the computational methodology through implementing experimental modal analysis on a scaled down physical model of a primary load-bearing component of the structural design. From the findings, a significant mass reduction percentage of 23.15%, utilizing the proposed perforation concept, was achieved in the final parametric design iteration relative to the baseline unperforated case while maintaining the same fundamental frequency. Dynamic loading analysis was also conducted, utilizing both the baseline unperforated and the finalized perforated designs, to check its capability to withstand realistic launch loads through applying quasi-static loads. The findings show that the final perforated design outperformed the baseline unperforated design with respect to the maximum displacements, maximum Von Mises stresses, and also the computed margin of safety. With these encouraging outcomes, the perforated design concept proved that it could provide an opportunity to develop low-cost satellite structural designs with reduced mass.

Highlights

Reduction of the mass of a satellite is one of the primary design drivers that must be considered when developing its system design
A reduction in mass for any satellite will result in significant cost savings for its space program. Another primary design driver for satellite design is the requirement imposed by launch providers onto any satellite being launched; namely, the value of the satellite’s fundamental natural frequency must be far from the FNF of the launcher, a value known as the critical natural frequency
Emphasis is placed on this specific modal parameter because launch service providers specify this critical value for the fundamental frequency in their user manuals, such as the mission planning guide published by Spaceflight, Inc. [4], a major provider of small satellite launch services

Summary

Introduction

Reduction of the mass of a satellite is one of the primary design drivers that must be considered when developing its system design. A reduction in mass for any satellite will result in significant cost savings for its space program Another primary design driver for satellite design is the requirement imposed by launch providers onto any satellite being launched; namely, the value of the satellite’s fundamental natural frequency (or FNF in the current work) must be far from the FNF of the launcher, a value known as the critical natural frequency. [4], a major provider of small satellite launch services This value is specified to avoid the possibility that the satellite’s fundamental natural frequency, that could be excited due to the highly dynamic launch loads, might synchronize with one of the launcher’s natural frequencies, causing mutual resonance between the two and leading to the loss of the launcher and its payloads, as mentioned by Garcia-Perez et al [5] as well as Fakoor et al [6]. The key parameter considered for comparison in the current work is the FNF of the cases taken under consideration in the current work, as will be shown in the relevant sections below

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