Carbon Fiber Reinforced Shape Memory Research Articles

Electrical/thermal triggering on shape memory composite tubes with different braiding angles

2D braided shape memory composite (SMPC) tubes, with near-net shape manufacturing and programmable, are widely utilized in smart structures. Here we have developed braided tubes of continuous carbon fiber reinforced shape memory polyurethane (SMPU) composites. This innovative design yields a synergistic boost in both mechanical strength, shape memory functionality, and dual-trigger responsiveness. The mechanical properties, electrical/thermal shape memory performance, and recovery force of the SMPC tubes with various braiding angles have been investigated. The effects of braiding angle, temperature dependence, and applied current on the mechanical properties and shape memory properties were revealed. We found a substantial increase in compression load and ring stiffness as the braiding angle increased and the temperature decreased. The SMPC tubes exhibited a recovery ratio of 99% under electrical and thermal triggering, demonstrating a more rapid shape recovery compared to the SMPU tubes solely under thermal triggering. The large-angle specimens exhibited shorter recovery times, higher recovery forces (up to 11.40 N), and faster responses upon electrical stimulation. The ability of SMPC tubes to generate a recovery force several times greater than their weight holds great potential for expanding the applications of smart actuators.

Dual thermal/electrical-driven compressive recovery behaviors of 3D braided shape memory composite tubes

3D braided shape memory composite (SMPC) tubes have great potential in designing smart structural components because of high inertia moment and near-net shape manufacturing. Here we developed a 3D braided carbon fiber reinforced shape memory polyurethane-based composite tube and investigated their thermal/electrical shape memory behaviors subjected to compression. The radial and axial compressive behaviors, thermally-electrically shape memory behaviors, and shape recovery forces of the SMPC tubes with different braiding angles were analyzed. The out-of-plane displacement and temperature field were obtained with 3D digital image correlation (DIC) and infrared thermography to characterize transverse compression deformation. We found that the 60° sample had the highest recovery force compared to the other braided angle samples, while the shape recovery speed was lower than small-angle samples. In the transverse compressive electro-thermal recovery test, the 30° sample reaches to glass transition temperature faster at the same voltage, and the 45° sample exhibits maximum shape recovery speed. The 3D braided SMPC tubes exhibited excellent electro-thermal shape memory behaviors and high recovery force, which were expected to extend the application of smart actuators.

Electro-induced tensile deformation of over-braiding composite tube with carbon fiber reinforced shape memory polyurethane filament

2D shape memory composite tubes, which has excellent flexibility and high durability, have been widely used in intelligent material design. Here we report fabrication of an over-braiding pure shape memory polyurethane (SMPU) and continuous carbon fiber reinforced SMPU (CCF/SMPU) braided tubes with different braided layers (L1, L2, L3). The dynamic thermomechanical behaviors, tensile properties, shape memory behaviors and tensile recovery forces had been investigated. Tensile shape recovery force was recorded to find effects of recovery temperature, applied voltage on the shape memory behaviors. We found that the tensile load, shape recovery ratio and recovery force increase with the braided layers increased. The maximum shape recovery ratio could be reached to 98.8% and shape recovery force of over-braiding CCF/SMPU composite tube was up to 14.825 N. The infilling of carbon fibers could improve the tensile strength and shape memory behaviors simultaneously. Such an effect could be benefit to explore applications of braided composite structures both with high strength and deformation recovery capacity.

Modeling the laminated carbon fiber reinforced shape memory polymer composites by using a refined plate theory

Laminated carbon fiber reinforced shape memory polymer composites (CFRSMPCs) have the advantages of simple structures and flexible properties in achieving a high loading capacity and novel shape memory effects. Because the mechanical properties of the laminated CFRSMPCs decrease rapidly during the process of carbon fiber failure, it should be avoided in application. To address this issue, modeling approach for the laminated CFRSMPCs is proposed by using a refined sinusoidal shear deformation plate theory (RPT) together with the simplified constitutive model of the CFRSMPCs, for the first time. Because the carbon fiber is liable to buckle under compression in the soft SMP matrix, the buckling behavior is studied here. For comparison, the pre-buckling loading capacities of the simply supported plates with different components are simulated. Furthermore, the effect of raising fiber volume fraction or adding layers on the loading capacity is studied. Therefore, this study provides useful guidance for reasonable design of laminated CFRSMPCs.

Effect of Molding Temperature on Shape Memory Performance of SMPC

Carbon fiber reinforced shape memory polymer composite (SMPC) is a kind of smart material with shape memory characteristics, which is widely used in aerospace, biomedicine, robotics and other fields. In this paper, SMPC was prepared by heating molding process at five different molding temperatures. The effect of molding temperature on the shape memory performance of SMPC was studied. The results show that the shape memory properties of SMPC are closely related to the infiltration effect during the preparation process. When the molding temperature is 70 °C, SMPC has an optimum penetration effect and the preparation defects are effectively controlled. The shape fixing rate is 84.3%, and the shape recovery rate is 94.7%, which lays a foundation for the better application of shape memory composite.

Temperature dependence of elastic constants in unidirectional carbon fiber reinforced shape memory polymer composites

The work describes a model to predict the elastic constants of unidirectional carbon fiber reinforced shape memory polymer composites (SMPCs) with different fiber volume fractions within the temperature range of 293 K to 393 K. The model is based on a theoretical description of the phase transition of the shape memory polymer (SMP). Two glassy phase volume fraction functions are developed, one based on the Eyring equation, the other based on the normal distribution equation. The longitudinal and transverse moduli, axial and transverse shear moduli, and axial Poisson's ratio are derived by using the glassy phase volume fraction function and modified rule of mixture. The axial Poisson's ratio increases with the temperature increase, while the other four constants decrease nonlinearly with rising temperatures. An inverse identification of the elastic constants at different temperature via numerical and experimental modal analysis from a flat SMPC laminate shows that the model proposed is adequate to describe the temperature dependence of the elastic constants of the laminate.

4D printed electro-induced continuous carbon fiber reinforced shape memory polymer composites with excellent bending resistance

Four-dimensional (4D) printing technology of continuous carbon fiber reinforced shape memory polymer composites is a potential manufacturing process for lightweight and high-strength intelligent composite structures. In this study, a 3D printer with dual feed channels based on the fused deposition modeling (FDM) was designed to fabricate continuous carbon fiber reinforced shape memory poly(lactic acid)-based composites (CFRSMPC). The impact of various printing parameters on the bending strength and flexural modulus of 4D printed CFRSMPC was evaluated by the three-point bending test. Meanwhile, mathematical prediction models of bending strength and modulus based on the existing experimental data were established. The electro-induced shape memory effect of 4D printed CFRSMPC was investigated by the electric heating shape recovery test. The shape recovery rate of the specimens was more than 95%, indicating that the resistance heating method is stable and feasible. The quantitative effect of bending angle and temperature on the resistance of CFRSMPC during the programming and recovery process was further investigated. The results demonstrated that the real-time deformation of the CFRSMPC could be monitored by the resistance measurement method. It can be concluded that the CFRSMPC fabricated using the 4D printing method can serve as potential building blocks for electrically activated and deployable structures.

Modeling the thermomechanical behavior of carbon fiber–reinforced shape memory polymer composites under the finite deformation

In this article, a thermoviscoelastic constitutive model is introduced to describe the unidirectional continuous elastic fiber–reinforced shape memory polymer composites under the finite deformation. Although the shape memory polymers can be used in finite deformations, only a small strain can be applied on the carbon fiber for its small failure tensile strain (about 2%). Using the model, the effective strain of the carbon fiber for the unidirectional continuous carbon fiber–reinforced shape memory polymer composites can be derived. It is found that the carbon fiber–reinforced shape memory polymer composites with the fiber inclination angle in a typical range can be used in the finite deformation, without failure of the carbon fiber. Besides, a simplified buckling model is proposed to predict the fiber buckling under axial compression. It is calculated that the buckling critical stress is rather small. Therefore, it should be avoided in application. As for carbon fiber–reinforced shape memory polymer composites, the bending driving capacity is the crucial property in their applications. Hence, the shape memory effect of the carbon fiber–reinforced shape memory polymer composite beam under the finite deformation is also studied here. The findings can be used to provide guidance for the design and application of the carbon fiber–reinforced shape memory polymer composites and their structures.

Study on 3D printing process of continuous carbon fiber reinforced shape memory polymer composites

In this paper, shape memory polymer (SMP) and continuous carbon fibers (CCF) were utilized as raw materials to manufacture composites by means of 3D printing based on FDM. Various process parameters were systematically studied by the orthogonal experiment to find out the optimal process combination where interfaces and mechanical properties of printed composites specimens were treated as research objectives. The influence of each factor on the performance of the specimen was discussed. The results indicated that the mechanical properties were preferable when the printing temperature was 200°C, the printing speed was 4.5mm/s, the scanning pitch was 1.1 mm, and the ply stacking sequence was 0°. Furthermore, the fiber content had little effect on the shape memory performance of the polymer matrix. The rapid manufacture of shape memory carbon fiber composites has potential use in the field of aerospace.

Carbon fiber reinforced shape memory epoxy composites with superior mechanical performances

For the shape memory polymers' (SMPs) applications in demanding, high performance scenarios are usually limited by their poor mechanical performances during shape transformation. In this work, shape memory epoxy composites (SMEPCs) with superior mechanical properties are fabricated by adding various short and continuous carbon fibers (CFs) into neat shape memory epoxies (SMEPs) matrix. The resultant SMEPC's storage modulus (E’) at room temperature is as high as 37 GPa, and the maximum recovery force exceeds 4.4 GPa, with good shape memory capabilities. These properties are at least an order of magnitude higher than those in existing typical SMP systems. The excellent mechanical properties of the fibers and their ability to retard crack propagation in the matrix are believed to play an important role in achieving high moduli below and above the shape-memory triggering temperature. The potential applications of such SMEPCs are demonstrated with wind blades. Experimental results and numerical models regarding air flow velocity variation as initiated by shape change in the blades indicate that our SMEPCs can sustain continuous stable mechanical state and provide variable wind speeds. These CF reinforced SMEPCs can be employed as smart structural materials to automatically switch shapes in response to the change in environment, such as those seen in aero foils and energy harvesters.

Integrative hinge based on shape memory polymer composites: Material, design, properties and application

Self-deployable structures based on shape memory polymer composites (SMPCs) have the capability of self-deploy, light weight and high load-bearing. This paper presents the detail of an integrative hinge fabricated by carbon fiber reinforced shape memory epoxy composites in the sequence of material selection, structure design and manufacture, material and structure experiments, and application. DMA experiments have been conducted to figure out the temperature sensitivity of SMP. The temperature dependent elastic modulus and strength of SMPC were determined by tensile experiments. Results from three point bending tests and shape memory recovery tests verify the variable stiffness of the integrate SMPC hinge under different temperatures and superior shape memory properties. Strain distribution during bending process are obtained from both digital image correlation (DIC) measurements and ABAQUS simulation, showing good consistency with each other. To compare the modal characteristics with traditional SMPC hinge, modal testing and computation have been designed with free boundary condition. It can be found that the integrative SMPC hinges have the characteristics of improved reliability and performance, and higher post-deployment stiffness and strength, when compared to traditional SMPC hinges. Finally, prospective applications of the self-deployable structure have also been illustrated.

Recovery torque modeling of carbon fiber reinforced shape memory polymer nanocomposites

Carbon fiber and carbon nanofiber paper (CF&CNFP) can be incorporated into shape memory polymers (SMPs) to increase electrical conductivity and allow high speed electrical actuation with a low power. This paper studies the interactions among the recovery torques of CF&CNFP and SMP and the gravity torque during the shape recovery process. The proposed recovery torque model in a SMP CF&CNFP based structure is validated by experimental data obtained using a recently developed low cost, non-contact measurement testbed.

Preparation and Properties of Shape Memory Epoxy Resin Composites

Kevlar fiber and carbon fiber reinforced shape memory epoxy composites were prepared respectively. The fold-deploy shape memory properties of the composite system were studied at the temperature which was 30°C higher than the glass transition temperature of resin. The results shows that shape fixed rate and shape recovered rate of the composites are decreased with the increase of Kevlar and carbon fiber volume. The shape fixed rate of Kevlar fiber reinforced shape memory composite is higher than that of carbon fiber reinforced shape memory composite, but the shape recovered rate of the former is much lower than the latter.

Carbon Fiber Reinforced Shape Memory Polymer Composites

In this paper we present results on the deformation of carbon fiber reinforced shape memory polymer matrix composites for deployable space structure applications. The composites were processed using resin transfer molding or a pre-impregnated (pre-preg) laminate press, with both satin and plain weave fiber architectures. The polymer matrix glass transition temperature, T g, was approximately 95°C. Composite specimens were bent to specific radii at T = 120°C, and cooled while constrained to a temperature of 25°C, which left them frozen in the bent state. Heating the specimens above T g caused the composites to return to their original unbent shape with up to 95% recovery based on bend angle. The effect of constraint hold times up to 350 hours on the recoverability was found to be negligible. Microscopic investigations revealed that the dominant local deformation mode of the composites was buckling of the carbon fibers on the inner surface of the bend. Localized buckling out of the material plane lead to detrimental interfacial matrix failure while dispersed in-plane buckling was elastic and non-damaging. A clear path for tailoring the shape memory polymer composites to facilitate in-plane elastic buckling is presented and tested. The improved materials can bend to local radii of curvature, R, of 1.6 mm with full recoverability and negligible local damage.