Thermal morphing anisogrid smart space structures: Part 1. Introduction, modeling, and performance of the novel smart structural application

Abstract

To meet the requirements for the next generation of space missions, a paradigm shift is required from current structures that are static, heavy, and stiff to innovative structures that are adaptive, lightweight, versatile, and intelligent. The largest benefit provided by this new structural concept is in the ability to deliver high precision position stability. The conventional high precision structural design uses two decoupled systems to achieve positional stability. First, a high mass structure delivers the effectively infinite stiffness and thermal stability so that no deformations occur under all operational loading conditions. Second, to meet the morphing and on-orbit positional requirements, supplementary mechanisms provide the nano, micro, and macro displacement control required. This paper proposes the use of a novel morphing structure, the thermally actuated anisogrid morphing boom, to meet the design requirements through actively morphing the primary structure in order to adapt to the on-orbit environment and meet both requirements in a consolidated structure. The proposed concept achieves the morphing control through the use of thermal strain to actuate the individual helical members in the anisogrid structure. Properly controlling the temperatures of multiple helical members can introduce six degree of freedom morphing control. This system couples the use of low coefficient of thermal expansion materials with precise thermal control to provide the high precision morphing capability. This concept has the potential to provide substantial mass reductions relative to current methods and meet the high precision displacement requirements of spacecraft systems. This paper will detail the concept itself, demonstrate the modeling procedure, and investigate the design space to quantify the potential of the thermally morphing anisogrid smart structure.