Design and Analysis of SMA-Based Tendon for Marine Structures

A tension-leg platform (TLP), as an offshore structure, is a vertically moored floating structure, connecting to tendon groups, fixed to subsea by foundations, to eliminate its vertical movements. TLPs are subjected to various non-deterministic loadings, including winds, currents, and ground motions, keeping the tendons under ongoing cyclic tensions. The powerful loads can affect the characteristics of tendons and cause permanent deformation. As a result of exceeding the strain beyond the elastic phase of the tendons, it makes unbalancing on the floated TLPs. Shape memory alloy (SMA)-based tendons due to their superelasticity properties may potentially resolve such problem in TLP structures. In the present work, performance and functionality of SMA wire, as the main component of SMA-based tendon under cyclic loading, have been experimentally investigated. It shows a significant enhancement in recovering large deformation and reduces the amount of permanent deformation

The Recent Advances in Magnetorheological Fluids-Based Applications

The magnetorheological fluids (MRF) are a generation of smart fluids with the ability to alter their variable viscosity. Moreover, the state of the MRF can be switched from the semisolid to the fluid phase and vice versa upon applying or removing the magnetic field. The fast response and the controllability are the main features of the MRF-based systems, which make them suitable for applications with high sensitivity and controllability requirements. Nowadays, MRF-based systems are rapidly growing and widely being used in many industries such as civil, aerospace, and automotive. This study presents a comprehensive review to investigate the fundamentals of MRF and manufacturing and applications of MRF-based systems. According to the existing works and current and future demands for MRF-based systems, the trend for future research in this field is recommended

Impact Analysis of MR-Laminated Composite Structures

Laminated composite structures are being used in many applications, including aerospace, automobiles, and civil engineering applications, due to their high stiffness to weight ratio. However, composite structures suffer from low ductility and sufficient flexibility to resist against dynamic, particularly impact loadings. Recently, a new generation of laminated composite structures has been developed in which some layers have been filled fully or partially with magnetorheological (MR) fluids; hereafter we call them MR-laminated structures. The present article investigates the effects of MR fluid layers on vibration characteristics and specifically on impact loadings of the laminated composite beams. Experimental works have been conducted to study the dynamic performance of the MR-laminated beams

Hysteresis Behavior of Pre-Strained Shape Memory Alloy Wires Subject to Cyclic Loadings: An Experimental Investigation

Shape memory alloys (SMAs) are a class of smart materials with the ability to recover their initial shape after releasing the applied load and experiencing a relatively large amount of strain. However, sequential loading and unloading which is an unavoidable issue in many applications significantly reduces the strain recovery of SMA wires. In the present work, experimental tests have been performed to study the pre-strain effect of SMA wires on hysteresis behavior of SMA under cyclic loadings. The effects of cyclic loading on austenite and martensite properties have been investigated. SMA wires with diameter of 1.5 mm and length of 560 mm subjected to about 1000 cycles show about 3 mm residual deformation, which is approximately equal to 0.5% residual strain. It is observed that applying 1.7% pre-strain on the SMA wire fully eliminates the residual strain due to cyclic loading

Shape memory allow-magnetorheological fluid core bracing system

Magnetorheological fluid (MRF) and shape memory alloy (SMA) are two smart materials used in many protective systems in civil engineering to mitigate unpredicted hazards. Isolation systems, dampers, and bracing systems are examples of smart protective systems integrated with civil infrastructures, such as building, to enhance their dynamic behaviour. Among them, bracing systems are the most common technique to keep buildings safe and healthy under seismic loads. In this study, both materials are used to develop a new bracing system called the SMA-MRF core-based bracing. A prototype of the system is fabricated and tested by the loading frame machine to prove the functionality of the system regardless of loading directions. Then, a numerical model of the systems is developed in the Open System for Earthquake Engineering Simulation (OpenSees). This model is implemented in a simplified two-story steel frame and exposed to the simulated ground motions. It is noted that the system improves the structural dynamic behaviour, such as the drift ratio, in the time-domain as well as frequency-domain. A control strategy is applied to the SMA-MRF core bracing systems. It is found that the system enhances the dynamic response with the embedded controller. The experimental results indicate that pre-straining SMA elements lead to a sharp increase in the energy absorption capacity as well as the recovery ability under short and long-term loadings. It is worth mentioning that the pre-strained SMA maintains the specifications, particularly the recovery capability, rather than conventional SMA under simulated short- and long-term loading.Applied Science, Faculty ofEngineering, School of (Okanagan)Graduat

Optimal Design of Adaptive Laminated Beam Using Layerwise Finite Element

First, an efficient and accurate finite element model for smart composite beams is presented. The developed model is based on layerwise theory and includes the electromechanical coupling effects. Then, an efficient design optimization algorithm is developed which combines the layerwise finite element analysis model for the smart laminated beam, sensitivity analysis based on analytical gradients and sequential quadratic programming (SQP). Optimal size/location of sensors/actuators is determined for dynamic displacement measurement purposes and for vibration control applications. For static and eigenvalue problems, the objective is to minimize the mass of the beam under various constraints including interlaminar stresses, displacements, and frequencies. For transient vibration problems, the objective is the minimization of the actuation control effort to suppress the vibration in a controlled manner. Illustrative examples are provided to validate the formulation and to demonstrate the capabilities of the present methodology