As a new class of smart materials, shape memory polymers and their composites (SMPs and SMPCs) can respond to specific external stimulus and remember the original shape. There are many types of stimulus methods to actuate the deformation of SMPs and SMPCs, of which the thermal- and electro-responsive components and structures are common. In this review, the general mechanism of SMPs and SMPCs are first introduced, the stimulus methods are then discussed to demonstrate the shape recovery effect, and finally, the applications of SMPs and SMPCs that are reinforced with fiber materials in aerospace are reviewed. SMPC hinges and booms are discussed in the part on components; the booms can be divided again into foldable SMPC truss booms, coilable SMPC truss booms and storable tubular extendible member (STEM) booms. In terms of SMPC structures, the solar array and deployable panel, reflector antenna and morphing wing are introduced in detail. Considering the factors of weight, recovery force and shock effect, SMPCs are expected to have great potential applications in aerospace.

https://iopscience.iop.org/article/10.1088/0964-1726/23/2/023001/pdf

Shape memory polymers and their composites in aerospace applications: a review

A review on large deployable structures for astrophysics missions

Inflatable structures offer the potential of compactly stowing lightweight structures,
which assume a fully deployed state in space. An important category of space inflatables
are cylindrical booms, which may form the structural members of trusses or the support
structure for solar sails. Two critical and interdependent aspects of designing inflatable
cylindrical booms for space applications are i) packaging methods that enable compact
stowage and ensure reliable deployment, and ii) rigidization techniques that provide
long-term structural ridigity after deployment. The vast literature in these two fields
is summarized to establish the state of the art.

/pdf/review-of-inflatable-booms-for-deployable-space-structures-5atrdj1lxs.pdf

Review of Inflatable Booms for Deployable Space Structures: Packing and Rigidization

Research on aircraft morphing has exploded in recent years. The motivation and driving force behind this has been to find new and novel ways to increase the capabilities of aircraft. Materials advancements have helped to increase possibilities with respect to actuation and, hence, a diversity of concepts and unimagined capabilities. The expanded role of unmanned aerial vehicles (UAVs) has provided an ideal platform for exploring these emergent morphing concepts since at this scale a greater amount of risk can be taken, as well as having more manageable fabrication and cost requirements. This review focuses on presenting the role UAVs have in morphing research by giving an overview of the UAV morphing concepts, designs, and technologies described in the literature. A presentation of quantitative information as well as a discussion of technical issues is given where possible to begin gaining some insight into the overall assessment and performance of these technologies.

https://iopscience.iop.org/article/10.1088/0964-1726/20/10/103001/pdf

Morphing unmanned aerial vehicles

This study aims to enable solid-state aerodynamic force generation in high-dynamic-pressure airflow. A novel, high-load-output, bidirectional variable-camber airfoil employing a type of piezoceramic composite actuator known as a Macro-Fiber Composite is presented. The novel airfoil employs two active surfaces and a single four-bar (box) mechanism as the internal structure. The unique choice of boundary conditions allows variable and smooth deformation in both directions from a flat camber line. The paper focuses on actuation modeling and response characterization under aerodynamic loads. A parametric study of aerodynamic response is employed to optimize the kinematic parameters of the airfoil. The concept is fabricated by implementing eight Macro-Fiber Composite 8557-P1-type actuators in a bimorph configuration to construct the active surfaces. The box mechanism generates deflection and camber change as predicted. Wind-tunnel experiments are conducted on a 12.6% maximum thickness, 127 mm chord airfoil. Aerodynamic and structural performance results are presented for a flow rate of 15 m /s and a Reynolds number of 127,000. Nonlinear effects due to aerodynamic and piezoceramic hysteresis are identified and discussed. A lift coefficient change of 1.54 is observed purely due to voltage actuation. Results are compared with conventional, zero-camber NACA and other airfoils. A 72% increase in the lift-curve slope is achieved when compared with a NACA 0009 airfoil.

Novel, Bidirectional, Variable-Camber Airfoil via Macro-Fiber Composite Actuators

https://imageserv5.team-logic.com/mediaLibrary/93/Rigidizable_Materials_for_use_in_Gossamer_Space_Inflatable_Structures.pdf

Rigidizable Materials for use in Gossamer Space Inflatable Structures

Inflatable and Rigidizable Wing Components for Unmanned Aerial Vehicles

Ultra-lightweight inflatable rigidizable space structures have been identified as an enabling technology for many large-scale and Gossamer type spacecraft planned by NASA and DoD for future space missions. The unique benefits of this class of structure, such as low packing volume, reduced complexity, and reduced mass, enable the development of large antennas, solar sails, and sunshields that would have been otherwise unrealizable. Through the maturation of this technology, many applications such as space based radar would benefit directly, and other applications such as mechanical actuation devices would benefit indirectly but significantly from material advancements. ILC Dover, under contract to the Jet Propulsion Laboratory (JPL) and NASA Langley Research Center (LaRC), has developed an ultra-lightweight inflatable rigidizable boom structure for use on gossamer spacecraft. The wall of the boom structural component is comprised of a grid-work of equilateral triangles that provide isotropic performance properties. This type of construction is termed an isogrid boom (See Figure 1). The grid-work is encased in two tubular polymeric films that act as gas containment vessels to enable inflation for deployment of the structure, and prevent the material from adhering to itself when packed. The exterior film also provides insulation to control the thermal conditions that govern the deployment process and structural performance in space. This structural concept was selected for study because of its high structural efficiency and simplicity in design. The material used in the fabrication of the isogrid structure is a composite, which consists of graphite and a shape memory polymer (GR/SMP). This GR/SMP material acts as a thermoplastic material and is able to be repeatedly heated and cooled to alter the structural shape. This allows the gossamer structure flight hardware to be packed and deployed for evaluation several times during ground test for checkout prior to launch and deployment in space. Shape memory polymers exhibit the unique property of returning to the originally formed shape when heated in a packed condition. In the case of structures with considerable deployment loads, inflation is used in conjunction with the weak SMP restoring force for deployment. This type of material was selected for study because of its structural performance properties, ability to be deployed and rigidized several times prior to launch, and storage life. The overriding goal was to develop a structural rigidizable beam technology that was close to flight readiness. This goal was met by performing numerous materials development tests on several candidate composite materials, manufacturing and testing numerous subcomponents and tube sections in simulated space and lab environments, and performing a deployment and rigidization test of a long boom section in a simulated space environment. The summation of the data indicated that the GR/SMP Isogrid was at a NASA Technology Readiness Level TRL of 5 to 6, but further study is required before the technology can be transitioned to a flight program. INTRODUCTION AIAA-2002-1297 Figure 1. 24K Tow Inflatable Isogrid Boom without Membranes * ILC Dover, Inc., Frederica, DE † Member AIAA ‡ Associate Fellow AIAA Copyright © 2002 by ILC Dover, Inc. Published by the American Institute of Aeronautics and Astronautics, Inc., with permission.

https://imageserv5.team-logic.com/mediaLibrary/93/Inflatable_Rigidizable_Isogrid_Boom_Development.pdf

Inflatable rigidizable isogrid boom development

A boom structure deployed by inflating the structure to a desired shape and rigidizing the structure via an external influence. The structure frame has a series of frame members which are made of a fibrous material and a resin material. This frame is encased in between a pair of membrane layers, an inner membrane inflatable to move the frame into its desired shape and an outer membrane that allows for folding the structure. Following inflation of the inner layer, an external influence acts on the resin material to solidify it, and render the structure rigid. The external influence may also act on the resin material to soften it when it is already rigid, to allow for collapsing and folding of the structure.

Inflatable rigidizable boom

This paper presents development of a structural model of warping inflatable wings. In order to quickly and effectively analyze the effects of aerodynamic loading and to consider design options for warping actuation, a detailed finite element model is required. The methodology used to develop and initially validate a finite element model of an inflatable wing is described in this paper. The wing is a complex structural system including intricate geometry, internal pressurization and a woven fabric shell structure. This effort includes determination of material properties via laboratory tests. These are verified with finite element simulations of simple inflatable cylinders constructed of similar material. The process used to create a finite element simulation of the wing is presented, including modeling assumptions and nonlinear analysis stages. Results for various loadings of interest are included. Finally, the paper presents initial validation of the finite element model using results of static cantilever wing bending and twisting loads applied at the inflatable wing tip. Although the model represents important deformation characteristics of the inflatable wing, it is generally too stiff compared to experimental results. Future modifications to the model and further validation are also discussed.

https://imageserv5.team-logic.com/mediaLibrary/93/Development_of_a_Finite_Element_Model_of_Warping_Inflatable_Wings.pdf

Stephen Scarborough

Papers

Rigidizable Materials for use in Gossamer Space Inflatable Structures

Inflatable and Rigidizable Wing Components for Unmanned Aerial Vehicles

Inflatable rigidizable isogrid boom development

Inflatable rigidizable boom

Development of a Finite Element Model of Warping Inflatable Wings