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Magnetorheological (MR) elastomers are composite materials consisting of magnetic particles in elastomer matrices, whose mechanical properties can be influenced by applying a magnetic field. Main parameters which determine the behavior of these smart materials are the concentration of the magnetic particles and the mechanical stiffness of the elastomer matrix. The viscoelastic properties of silicone-based MR elastomers are outlined in terms of their storage and loss moduli. The mechanical behavior of the material is also influenced by a magnetic field during the curing of the elastomer matrix, which leads to materials with anisotropic microstructures. The storage modulus of soft elastomer matrix composites can be increased in the presence of a magnetic field by significantly more than one order of magnitude or several hundreds of kPa. The relative increase exceeds that of all previously reported data. A shape memory effect, i. e. the deformation of an MR elastomer in a magnetic field and its return to original shape on cessasion of the magnetic field, is described.

In recent years, Nitinol, near-equiatomic nickel-titanium alloys, have found growing applications in medical technology and joining technology, due to their special characteristics such as shape memory, superelasticity and biocompatibility. The production of Nitinol tube cost-effectively remains a technical challenge. In this paper, we describe a hot drawing process for Nitinol tube production. A Nitinol tube blank and a metal core are assembled together. The assembly is hot drawn for several passes to a final diameter. The metal core is then plastically stretched to reduce its diameter and removed from the tube. Hot drawing process has been applied to Ni50.7Ti and Ni47Ti44Nb9 alloys. Nitinol tubes of 13.6 mm outer diameter and 1 mm wall thickness have been successfully produced from a tube blank of 20 mm outer diameter and 3.5 mm thickness.

Shape memory polymer composite (SMPC) structures, due to their ability to be formed into a small compact volume and then transform back to their original shape, are considered as a solution in the design of light-weight large deployable space structures. There is a wide array of constitutive and qualitative work being done on SMPC’s but little or no development of dynamic equations. This paper documents a macroscopic model for the shape fixation and shape recovery processes of a SMPC cantilever beam. In particular the focus is on the shape fixation process, whereby a quasi-static equilibrium model can be used instead of a full equation of motion. Numerical results are obtained in this regard by use of finite difference approximation with Newton’s method. This formulation combines a nonlinear geometric model with a temperature dependent constitutive law. Additionally, the dynamic equations of the SMPC cantilever are derived. Future work will include a dynamic numerical model, and a finite element model of the SMPC structure.

Due to their large latent heats, pseudoelastic Ni–Ti-based shape memory alloys (SMAs) are attractive candidate materials for ferroic cooling, where elementary solid-state processes like martensitic transformations yield the required heat effects. The present work aims for a chemical and microstructural optimization of Ni–Ti for ferroic cooling. A large number of Ni–Ti-based alloy compositions were evaluated in terms of phase transformation temperatures, latent heats, mechanical hysteresis widths and functional stability. The aim was to identify material states with superior properties for ferroic cooling. Different material states were prepared by arc melting, various heat treatments and thermo-mechanical processing. The cooling performance of selected materials was assessed by differential scanning calorimetry, uniaxial tensile loading/unloading, and by using a specially designed ferroic cooling demonstrator setup. A Ni${}_{45}$Ti${}_{47.25}$Cu₅V${}_{2.75}$ SMA was identified as a potential candidate material for ferroic cooling. This material combines extremely stable pseudoelasticity at room temperature and a very low hysteresis width. The ferroic cooling efficiency of this material is four times higher than in the case of binary Ni–Ti.

In this study, we synthesized semi-crystalline thermosetting polymer that have two-way-reversible shape memory effect (2W-SME) with a single crystalline phase and an amorphous phase. The polymer could be synthesized readily and its glass transition temperature (Tg) could be tuned over a wide range. The effect of acrylic monomers on the degree of cross-linking, the effects of different conditions, the applied stress, the acrylic monomers used, and the phase ratio of the crystalline and amorphous domains on the 2W-SME were studied. Measurement results confirmed that the polymer showed the 2W-SME and, the strongest 2W-SME achieved under the optimized conditions corresponded to a reversible deformation of 8.5%.

4D printing of biocompatible shape memory polymer materials is of great significance in the biomedical field. The addition of PCL material into PLA matrix is capable of modulating the elastic modulus of the material while remaining a reduced degradation rate. However, the influence of 4D printing parameters and shape programming parameters on their shape memory properties had not been systematically investigated. Here, we examine the effects of 4D printing process parameters and shape programming parameters on the shape memory properties of PLA/PCL composites. We first explore the effects of key printing parameters on the print quality and shape memory properties of pure PLA materials, and select composites with a PCL mass fraction of 15% to fully characterize their thermodynamic properties. The effects of programming stress and programming temperature on the shape memory properties of the PCL15 composites are analyzed. Finally, the artificial neural network algorithm is employed to optimize its programming parameters, and brings 5.76% enhancement of shape recovery ratio compared with that before optimization. This work provides a systematic study of the shape memory properties of 4D printed PLA/PCL composites, paving the way for promoting their application in the biomedical industry.

This chapter introduces the principle of shape memory function in polymers and classifies shape memory polymers according to their molecular structures, trigger patterns and applications based on a literature review. One of the novel functional shape memory polymers with substrate bonding antibacterial activity is detailed and a new design of supramolecular shape memory polymers is discussed. Finally, shape memory fibres are introduced in comparison with other existing man-made fibres to clarify the uniqueness of such smart textile materials.