Topic
Smart material
About: Smart material is a research topic. Over the lifetime, 3704 publications have been published within this topic receiving 74280 citations. The topic is also known as: intelligent material & responsive material.
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TL;DR: In this paper, a commercial 3D-printer was used to produce 3D printed polyurethane-based shape memory polymers (SMPs) specimens and an annealing heat treatment was applied to some of the specimens.
Abstract: Material extrusion additive manufacturing (MEAM), also known as three-dimensional (3D) printing, is a popular additive manufacturing technique suitable for producing 3D shapes using thermoplastic materials. The majority of companies that design and test 3D printing machines work with thermoplastic acrylonitrile butadiene styrene (ABS) and polylactic acid (PLA) filaments. It is, however, crucial to utilize different types of filaments for a broader range of applications with different mechanical property requirements. Shape memory polymers (SMPs) are smart materials that react to an applied stimulus in order to recover large strains. MEAM techniques may be used for the production of SMP-based parts, allowing for smart structures to be created in a wide variety of geometries. In this work, a commercial 3D-printer was used to produce 3D printed polyurethane-based SMP specimens. An annealing heat treatment was applied to some of the specimens. Mechanical and thermomechanical testing was conducted to study the effects of testing temperatures and annealing heat treatments on the tensile and shape memory properties of the samples. 3D printing was shown to be a suitable technique for producing SMP parts capable of retaining good shape memory characteristics. Different annealing heat treatments and test temperatures were found to have considerable effects on the SMP specimen properties. In particular, annealing the specimens at 85 °C for 2 h helped to improve the rate of shape recovery and the consistency of mechanical test results.
75 citations
TL;DR: In this paper, a flexible phase change composite with unidirectional shape memory effects and motion detection properties was proposed, which is composed of carbonized cotton cloth as a conductive supporting structure, paraffin wax as a latent heat storage material and thermoplastic polyurethane as a protective layer.
Abstract: In addition to their lower thermal conductivity, leakage during the melting phase and poor energy conversion ability, the fragility of phase change materials is an issue that is worth addressing to widen their application scope. Herein, we propose a low-cost and facile method to develop a flexible electro-driven phase change composite with unidirectional shape memory effects and motion detection properties. The phase change composite is composed of carbonized cotton cloth as a conductive supporting structure, paraffin wax as a latent heat storage material and thermoplastic polyurethane as a protective layer. The woven framework of carbonized cloth endowed the paraffin wax with the ability to generate Joule heating at a lower voltage due to its high electrical conductivity (374 S m−1). The multifunctional layer of thermoplastic polyurethane wrapped the carbon cloth/paraffin and greatly improved the form-stability, flexibility and mechanical strength of the composite. Shape fixity and shape recovery properties of the composite were achieved by the synergic effect of the phase transition in paraffin and the elasticity of thermoplastic polyurethane. Moreover, the presence of conductive carbon cloth enabled the composite to achieve good electrothermal conversion efficiency and motion sensing properties. The fabricated flexible phase change composite may serve as a smart material for versatile thermal management applications.
75 citations
TL;DR: This study links the topology of the network organization in space to its nonlinear rheological response preceding yielding and damage: this analysis elucidates how the network connectivity alone could be used to modify the gel mechanics at large strains, from strain-softening to hardening and even to a brittle response.
Abstract: The structural complexity of soft gels is at the origin of a versatile mechanical response that allows for large deformation, controlled elastic recovery, and toughness in the same material. A limit to exploiting the potential of such materials is the insufficient fundamental understanding of the microstructural origin of the bulk mechanical properties. Here we investigate the role of the network topology in a model gel through 3D numerical simulations. Our study links the topology of the network organization in space to its nonlinear rheological response preceding yielding and damage: our analysis elucidates how the network connectivity alone could be used to modify the gel mechanics at large strains, from strain-softening to hardening and even to a brittle response. These findings provide new insight for smart material design and for understanding the nontrivial mechanical response of a potentially wide range of technologically relevant materials.
74 citations
TL;DR: In this article, a shear mode magnetorheological fluid damper is attached to a 12.65 m inclined flat-sag steel cable to reduce cable vibration in cable-stayed bridges.
Abstract: Stay cables, such as are used in cable-stayed bridges, are prone to vibration due to their low inherent damping characteristics. Transversely attached passive viscous dampers have been implemented in many bridges to dampen such vibration. However, only minimal damping can be added if the attachment point is close to the bridge deck. For longer bridge cables, the relative attachment point becomes increasingly smaller, and passive damping may become insufficient. A recent analytical study by the authors demonstrated that “smart” semiactive damping can provide increased supplemental damping. This paper experimentally verifies a smart damping control strategy employing H2 ∕linear quadratic Gaussian (LQG) clipped optimal control using only force and displacement measurements at the damper for an inclined flat-sag cable. A shear mode magnetorheological fluid damper is attached to a 12.65 m inclined flat-sag steel cable to reduce cable vibration. Cable response is seen to be substantially reduced by the smart da...
74 citations
TL;DR: In this paper, the authors report on the development of a wavelength demodulation system that is inexpensive and easily implemented with a minimum of equipment, which can process many fiber optic sensors, yet be small enough to be integrated within the structural interface and thereby address the interconnect problem.
Abstract: Smart materials and adaptive structures will require structurally integrated fiber optic sensing systems that can operate in practical situations including harsh environments. The intracore fiber optic Bragg grating has considerable potential to serve as the sensor of choice for this emerging field. However, its role has been impeded by the lack of a simple, passive and fast method of determining the wavelength of its narrow back-reflected optical signal. The authors report on the development of just such a wavelength demodulation system that is inexpensive and easily implemented with a minimum of equipment. Furthermore, they shall show that this approach lends itself to the development of an optoelectronic chip that could process many fiber optic sensors, yet be small enough to be integrated within the structural interface and thereby address the interconnect problem-potentially one of the most critical facing the development of practical smart structures.
74 citations