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Yes / Shape memory polymer (SMP) products have been developed for application as crack closure de-vices in concrete. They have been made from PET in the form of both fibres and hollow tubes. Here, manufacturing methods using die-drawing and mandrel-drawing to induce shape memory are reported. The fibre-based devices are incorporated into concrete and, upon triggering, exert shrinkage restraint forces that close cracks in the concrete. The evolution of shrinkage restraint force in the fibres as manufactured was measured as a function of temperature, showing stresses in excess of 35 MPa. Tendons consisting of fibre bundles are incorporated into concreate beams subjected to controlled cracking. When activated, the tendons reduce the crack widths by 80%. The same fibres are used to produce another class of device known as knotted fibres, which have knotted ends that act as anchor points when they incorporated directly into concrete. Upon acti-vation within the cracked concrete, these devices are shown to completely close cracks. The tubes are used to enclose and restrain prestressed Kevlar fibres. When the tubes are triggered, they shrink and release the prestress force in the Kevlar, which is transferred to the surrounding con-crete in the form of a compressive force, thereby closing cracks. The Kevlar fibres also provide substantial reinforcement after activation. The devices are shown to be able to partially and fully close cracks that have been opened to 0.3 mm and achieve post-activation flexural strengths com-parable to those of conventional reinforced and prestressed structural elements. Finally, a pre-liminary life cycle assessment study was used to assess the carbon footprint a nominal unit of concrete made with SMPs fibres compared to conventional concrete. / This research was funded by the UKRI-EPSRC Resilient Materials 4 Life (RM4L), grant number EP/P02081X/1 and the support of ARUP via the UKIMEA research funding.

As applications for shape memory polymers (SMPs) become more advanced, it is necessary to have the ability to monitor both the actuation and thermal properties of structures made of such materials. In this paper, a method of using three stereo pairs of webcams and a single thermal camera is studied for the purposes of both tracking three dimensional motion of shape memory polymers, as well as the temperature of points of interest within the SMP structure. The method used includes a stereo camera calibration with integrated local minimum tracking algorithms to locate points of interest on the material and measure their temperature through interpolation techniques. The importance of the proposed method is that it allows a means to cost effectively monitor the surface temperature of a shape memory polymer structure without having to place intrusive sensors on the samples, which would limit the performance of the shape memory effect. The ability to monitor the surface temperatures of a SMP structure allows for more complex configurations to be created while increasing the performance and durability of the material. Additionally, as compared to the previous version, both the functionalities of the testbed and the user interface have been significantly improved.

Les polymères à mémoire de forme (SMP) sont des matériaux qui peuvent revenir à leur forme d'origine lorsqu'un stimulus approprié (par exemple de la chaleur) est prévu. Ces polymères sont programmés par cycle de mémoire de forme qui se compose de deux parties: une partie de la programmation qui donne un effet mémoire de forme (SME) à savoir la forme temporaire pour le polymère et la partie de récupération où il revient à sa forme initiale. Les SMP ont une faible rigidité, donc, produisent de grandes déformations récupérables, mais produisent des forces de récupération faibles. Cependant, les composites SMP produisent des forces de récupération plus grandes car ils sont relativement rigide mais ont des souches moins récupérables. En outre, de forts actionneurs à mémoire de forme peuvent être produits si deux effets différents peuvent être combinés dans une structure unique. Une structure déjà active (par exemple des alliages à mémoire de forme) peut être intégré dans SMP. Par conséquent, un fort actionneur couplé peut être obtenu. [...] / Shape memory polymers (SMPs) are the materials which can return to their original shape when a suitable stimulus (e.g. heat) is provided. These polymers are programmed through shape memory cycle that consists of two parts: programming part which gives shape memory effect (SME) i.e. temporary shape to the polymer and the recovery part which return it to its original shape. SMPs have low stiffness, therefore, produce large recoverable strains, but produce low recovery forces. However, SMP composites produce larger recovery forces as they are relatively rigid but have less recoverable strains. Moreover, strong shape memory actuators can be produced if two different effects can be combined in a single structure. An already active structure (e.g shape memory alloys) can be embedded in SMP. Consequently, a strong coupled actuator can be obtained. In this work, the shape memory property of CBCM composite (an active composite that works on bimetallic affect) has been studied. CBCM stands for controlled behavior of composite material. CBCM activeness and its SM property has been coupled together to obtain a strong actuator. SM property has been obtained through thermo-mechanical programming at a temperature higher than glass transition temperature (Tg) of Epoxy resin used for its fabrication. The CBCM actuating properties have been studied through different one-step recoveries (unconstrained, constrained and recovery under load). Moreover, different asymmetrical CBCM composites have been developed by changing the position and orientation of the different layers used. These have been studied for their different actuation properties. Similarly, multi-step recoveries (unconstrained and constrained) have also been performed to show multi step actuation capabilities in CBCM. The actuating properties of CBCM have also been compared with symmetrical composite (SYM) to show the advantage of coupled properties in CBCM. It has been found that CBCM has the ability to give high strain, high recovery forces. Also, it can recover under load and recover to its original position at the temperatures lower than the deforming temperature used in the programming cycle.

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In the field of control systems, testbeds are a pivotal step in the validation and improvement of new algorithms for different applications. They provide a safe, controlled environment typically having a significantly lower cost of failure than the final application. Vision systems provide nonintrusive methods of measurement that can be easily implemented for various setups and applications. This work presents methods for modeling, removing distortion, calibrating, and rectifying single and two camera systems, as well as, two very different applications of vision-based control system testbeds: deflection control of shape memory polymers and trajectory planning for mobile robots. First, a testbed for the modeling and control of shape memory polymers (SMP) is designed. Red-green-blue (RGB) thresholding is used to assist in the webcam-based, 3D reconstruction of points of interest. A PID based controller is designed and shown to work with SMP samples, while state space models were identified from step input responses. Models were used to develop a linear quadratic regulator that is shown to work in simulation. Also, a simple to use graphical interface is designed for fast and simple testing of a series of samples. Second a robot testbed is designed to test new trajectory planning algorithms. A templatebased predictive search algorithm is investigated to process the images obtained through a lowcost webcam vision system, which is used to monitor the testbed environment. Also a userfriendly graphical interface is developed such that the functionalities of the webcam, robots, and optimizations are automated. The testbeds are used to demonstrate a wavefront-enhanced, Bspline augmented virtual motion camouflage algorithm for single or multiple robots to navigate through an obstacle dense and changing environment, while considering inter-vehicle conflicts, iv obstacle avoidance, nonlinear dynamics, and different constraints. In addition, it is expected that this testbed can be used to test different vehicle motion planning and control algorithms.

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