Fabric Reinforced Shape Memory Polymer Research Articles

Shape memory cyclic behavior and mechanical durability of woven fabric reinforced shape memory polymer composites

The shape memory cyclic behavior and mechanical durability of the shape memory polymer (SMP) and three woven fabrics (plain, twill, and satin weaves) reinforced shape memory polymer composite (WFR-SMPCs) are characterized to investigate the effect of woven textures on the mechanical and shape memory properties of WFR-SMPCs. Shape memory cycle test, shape memory durability test, and microscopic observation for SMP and WFR-SMPCs were carried out. Experimental results show that the SMP is temperature-sensitive, and higher temperature facilitates the shape memory performance of the material. The woven fabric reinforcements can significantly enhance the mechanical properties of the SMP matrix while still maintaining good shape recovery ratios above 98 % and shape fixation ratios above 90 % even though there is a slight decrease in these values. The twill WFR-SMPC displays the best mechanical performance. The satin WFR-SMPC has the highest shape recovery ratio. The twill WFR-SMPC performs the best in load-bearing capacity and recovery stress. The microscopic observations show that the rotational misalignment and bending of the fiber tows, and damage to the matrix are the main failure modes of the WFR-SMPCs at high shear strain.

Reversible shape memory behavior of knitting-fabric reinforced polymer matrix composites

Reversible self-shaping behavior has been occurred with chemically crosslinked polymers and multi-layer structures while this behavior is difficultly realized for the fabric reinforced polymeric composites. In this work, a thin weft plain knitted fabric reinforced shape memory polymer composites (SMPCs) with reversible shape memory effect were developed. The effect of sizes, knitting densities and actuated temperatures on reversible shape memory behavior of SMPC was investigated. The results show that the maximum self-bending curvature of SMPCs is 35.8 m-1 and the shape recovery ratio reaches 82.2 %. A simplified finite element model was established to simulate and analyze the process of self-bending with heating and self-recovery with cooling of SMPC. Interestingly, the SMPC in wale direction (90°) has the inverse self-bending curvature of −18.4 m-1 as compared with that of SMPC in course direction (0°). The complex double curvature self-bending behavior of SMPC was also demonstrated. This work helps to broaden the development and research of reversible shape memory composites.

A 3D Anisotropic Thermomechanical Model for Thermally Induced Woven-Fabric-Reinforced Shape Memory Polymer Composites.

Soft robotic grippers offer great advantages over traditional rigid grippers with respect to grabbing objects with irregular or fragile shapes. Shape memory polymer composites are widely used as actuators and holding elements in soft robotic grippers owing to their finite strain, high specific strength, and high driving force. In this paper, a general 3D anisotropic thermomechanical model for woven fabric-reinforced shape memory polymer composites (SMPCs) is proposed based on Helmholtz free energy decomposition and the second law of thermodynamics. Furthermore, the rule of mixtures is modified to describe the stress distribution in the SMPCs, and stress concentration factors are introduced to account for the shearing interaction between the fabric and matrix and warp yarns and weft yarns. The developed model is implemented with a user material subroutine (UMAT) to simulate the shape memory behaivors of SMPCs. The good consistency between the simulation results and experimental validated the proposed model. Furthermore, a numerical investigation of the effects of yarn orientation on the shape memory behavior of the SMPC soft gripper was also performed.

Electrothermally actuated properties of fabric-reinforced shape memory polymer composites based on core–shell yarn

Electrothermally actuated and mechanical properties are important for multifunctional application of fabric-reinforced shape memory polymer composites (SMPCs). Here we presented a new method to prepare the fabric-reinforced shape memory polymer thermoplastic composite molded with plain composite fabric. The composite fabric was weaved with continuous carbon fiber/shape memory polyurethane (CCF/SMPU) core–shell structure yarn. The effects of microstructure, layer number and carbon fiber (CF) content on flexural property, thermo-mechanical, shape recovery behaviors of SMPCs were studied. The flexural load and storage modulus were improved due to the introduction of carbon fiber. The shape recovery ratio of SMPCs could reach 99.3% under thermal and electrical stimulation. Some demonstrations of the SMPCs showed excellent electro-thermal recovery and higher deformability. The yarn and fabric structure are expected to have good potential in smart structure design.

An anisotropic visco-hyperelastic model for thermally-actuated shape memory polymer-based woven fabric-reinforced composites

An anisotropic visco-hyperelastic constitutive model for thermally-actuated woven fabric-reinforced shape memory polymer composites (SMPCs) is proposed. The viscoelasticity of the shape memory polymer and anisotropic hyperelasticity of the fabric are separately described. The second law of thermodynamics is used to derive the constitutive relations through decomposing the thermodynamic free energy. A woven fabric-reinforced SMPC is prepared and its thermomechanical and shape memory experiments are conducted to verify the proposed model. Comparison between the predicted and experiment results indicates an good consistency, which attests that the developed model can predict the anisotropic mechanical and shape memory properties of thermally induced SMPCs reinforced by woven fabrics effectively. And numerical investigation of the effect of fiber yarn orientation on the shape fixity and recovery is also performed.

Ground and geostationary orbital qualification of a sunlight-stimulated substrate based on shape memory polymer composite

A sunlight-stimulated substrate, named Mission SMS-I, carried out the orbital deployment experiment and anti-irradiation verification on an experimental geostationary satellite. It is the prototype of a solar array substrate which integrates the conventional substrate, support structure, and deployment function by using the carbon fabric reinforced shape memory polymer composite (SMPC). The substrate could deploy from the ‘Ω’ packaged configuration to the ‘-’ deployed configuration once its temperature is at or above the glass transition temperature. This paper presents details of the Mission SMS-I in a sequence of material preparation, structure design, manufacture, ground experiments, and orbital experiment. Results show that the Mission SMS-I can withstand the required mechanical and thermal conditions, successfully deploy in orbit and have a good long-term anti-irradiation capability. SMPC is a suitable choice for the substrate of solar arrays or any other deployable structures which need the actuation in material-level or directly exposed to the space environment.

Elastocaloric effects of carbon fabric-reinforced shape memory polymer composites

The applications of the elastocaloric cooling effect (eCE) of shape memory poly(cyclooctene) (PCO) to portable cold-storage devices at high temperatures have been demonstrated. These applications arise due to its good shape fixation properties upon cold-drawing. In this paper, we report that carbon fabric-reinforced PCO composites exhibit enhanced eCE compared to pure PCO due to the increased elasticity and Clausius–Clapeyron factor by carbon fabric reinforcement. The elastocaloric heating and cooling effects of PCO-based shape memory polymer composites (PCO-SMPCs) were characterized and predicted using a constitutive equation of woven fabric-reinforced SMPC and their eCE was analyzed in terms of thermodynamic parameters. Good agreement between experiments and simulations was obtained, showing that 3D finite element analysis can facilitates the design of surface adaptable solid-state coolers fabricated from PCO-SMPC with good efficiency and portability properties.

Three-dimensional constitutive model of woven fabric-reinforced shape memory polymer composites considering thermal residual stress

The mechanical modeling and simulation of woven fabric-reinforced shape-memory polymer composites (wf-SMPCs) are quite complex tasks because a temperature change introduces thermal stress that dramatically affects the interaction between the matrix and fiber. This study aimed to develop a new homogenized constitutive model for wf-SMPCs considering the thermally induced residual stress. The orthotropic properties of the wf-SMPC due to the woven fabric reinforcement were modeled using classical anisotropic hyperelasticity theorems. The stress generated in the hyperelastic model was then complemented by combining with the stress generated in the SMP constitutive equation and the thermal residual stress according to Eshelby’s inclusion theorem. The prediction capability of the proposed model was verified by three-point bending tests of the wf-SMPC having various fiber volume fractions. Finally, the unique features of the proposed constitutive model were investigated by experiments and simulation of a self-deployable antenna made of a wf-SMPC.

Thermo-mechanical modeling of woven fabric reinforced shape memory polymer composites

ABSTRACTIn order to predict thermo-mechanical properties of woven fabric reinforced shape memory polymer composites (WFRSMPCs), the multi-scale theory is employed to establish the microscopic model for fiber bundles and the mesoscopic model for WFRSMPCs respectively. Firstly, the viscoelastic properties of WFRSMPCs with different process parameters are studied numerically in the paper. Then the free recovery and the constrained recovery of WFRSMPCs are studied respectively and the effects of heating rates and process parameters on shape memory properties of WFRSMPCs are investigated. The research in the paper could provide a basis for design and application of WFRSMPCs in engineering.

A Comparative Analysis of Orientation on the Shape Memory Effect of Fabric Reinforced Shape Memory Polymer Composites

Shape memory polymer composites (SMPC) are a new kind of smart materials where many researches have been carried out. In SMPC, shape memory polymers serves as a matrix material and particles or fibers act as reinforcements. As structural applications demand structures to withstand load and stiffness, particles reinforced SMPC does not serve for it. Therefore fiber/fabric reinforced SMPC used widely for such applications. SMPC’S changes its shape during a typical thermo-mechanical cycle and retracts to its original shape upon external stimulus (temperature). Molecular mechanism is the driving force of these SMP’s. SMP consists of 1.molecular switches and 2. netpoints. This project deals with Epoxy shape memory resin (Matrix material) and fabrics such as Glass, Kevlar and Carbon (Reinforcements).A Comparative analysis was carried out to find which combination gives the best results by bend test. Different orientations were tried for bidirectional fabrics such as (0/90)3, (0/45)3, ((0/90)/(±45)/(0/90)) specimens. Finally it was concluded that Carbon fabric which has the orientation of (0/90/±45/0/90) gives better shape memory performance.

Environmental Durability of Fabric-Reinforced Shape-Memory Polymer Composites

This study is a baseline assessment of the environmental durability of current state-of-the-art, fabric-reinforced shape-memory (SM) materials being considered for morphing applications. Tensile dog-bone-shaped specimens are cut along three different directions, namely, along (0°), perpendicular (90°), and oblique (45°) to the planar orientation of the fabric. The elastomeric response and shape memory properties before and after simulated environmental exposure to moisture, lubrication oil, and UV radiation are measured. Weight loss of the as-received and conditioned specimens is monitored and the dog-bone-shaped specimens are subjected to recovery following fixation. Parameters being investigated include modulus in the glassy and rubbery state, stored strain, shape fixity, recovery stress, and unconstrained shape recovery. There is a twofold decrease in the composite stiffness as the material is cycled between room and elevated (above the glass transition) temperature. At room temperature, the 0-degree specimen has the maximum stiffness (5.8 GPa), failure strength (94 MPa), and failure strain (5.4%), while above the Tg, the 90-degree specimen has the least stiffness (∼18 MPa) and largest strain to failure (>200%). Thus, the composite exhibits large deformation in its rubbery state. Parameters which are strongly affected by the damage developed during the first SM cycle include rubbery and glassy (or unloading) moduli values measured during the second SM cycle, while smaller changes are observed in shape fixity and recovery properties.

A self-healing 3D woven fabric reinforced shape memory polymer composite for impactmitigation

In this paper, a three-dimensional (3D) woven fabric reinforced shape memorypolymer composite for impact mitigation was proposed, fabricated, programmedusing a three-step strain-controlled thermomechanical cycle at a pre-strain levelof 5% and machined to two groups of specimens (G1 and G2) with dimensions152.4 mm × 101.6 mm × 12.7 mm. The specimens were impact tested, transversely, centrally and repeatedly with 32 and42 J of energy. G1 specimens were healed after each impact until perforation occurred. G2specimens were not healed after each impact and served as controls. At 32 J impact energy,G2 specimens were perforated at the 9th impact while G1 specimens lasted until the 15thimpact; at 42 J impact energy, G2 specimens were perforated at the 5th impact while G1specimens were perforated at the 7th impact. Visual inspection, C-scan, and scanningelectron microscopy techniques were used to evaluate damage, failure modes, and healingefficiency.

形状記憶ポリマー／ＣＦＲＰハイブリッド積層板の曲げおよび振動特性の評価

Although fiber reinforced plastics (FRP) are often used for structural components and functional materials, the vibration reduction for FRP materials is still difficult. The hybrid construction of FRP is well known as more effective for the improvement of this property. In this paper, in order to improve damping characteristics of FRP materials, carbon fabric reinforced shape memory polymer (SMP/CFRP) hybrid laminates are developed. The bending and damping property is investigated by the three-point bending test and mechanical impedance method. The influence of lamination position and contents of SMP in hybrid laminates on mechanical property is discussed. The theoretical formula for bending modulus and bending strength was proposed, and the validity was confirmed by experiment. The results show that the developed hybrid laminates has high bending modulus and excellent damping properties.

Bending behavior of shape memory polymer based laminates

Shape memory polymers (SMP) are smart materials was characterized by the recoverability of shape memory effect, but its mechanical property such as the strength is low. In this study, for industrial applications, a carbon fiber fabric reinforced shape memory polymer was developed. Four kinds of specimens with different laminations of carbon fiber fabric and shape memory polymer sheet were prepared. The bending recoverability was investigated and compared between the SMP sheet substance and the developed SMP based laminates. Both of the materials were loaded and then unloaded repeatedly above the T g. The bending recoverability characterized by the bending angle, and the influence of weight of specimen was examined. Results show that the SMP based laminates developed have good shape recoverability, and their bending recovery ratio was larger than that of the SMP sheet at any recovery time. Furthermore, the bending recovery ratio was predicted with an analysis model and its result was compared with experiment values. The good agreement between the experiment and analysis suggests that the proposed analysis model is effective for the prediction of the bending recovery of SMP based laminates.

OS09W0348 Development and bending recovery properties of shape memory polymer based laminates

Shape memory polymer as one of smart materials has received much attention. It is characterized by the recoverability of shape memory effect, but its mechanical property such as the strength isn't strong enough. In this study, for the applications in the field of industry, the carbon fabric reinforced shape memory polymer was developed. The bending recoverability was investigated and compared between the SMP simple substance and the development composite material. Both of the materials were loaded and then unloaded repeatedly beyond Tg, and the bending recoverability was characterized by the bending angle and the influence of weight of specimen was also examined.