Rehabilitation of Concrete Beam by Using Martensitic Shape Memory Alloy Strands

2011 ◽  
Vol 243-249 ◽  
pp. 5527-5530 ◽  
Author(s):  
Di Cui ◽  
Guan Ping
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Crack Width ◽  
Concrete Beam ◽  
Single Point ◽  
Electrical Current ◽  
Reinforced Concrete Structures ◽  
Ordinary Concrete ◽  
Steel Bars ◽  
Three Stages

The rehabilitation properties of intelligent concrete beam reinforced with shape memory alloys (SMA) is investigated. In this study, SMA strands, made of 7 single wires, are used to replace the steel bars in ordinary concrete beam. The test of single point loading at the mid-span is conducted on the beam. The experiment has three stages including loading, unloading and heating the SMA strands. During heating the SMA strands by electrical current, the crack width can be reduced by taking the advantage of the shape memory effect of SMA strands. The results illustrate that SMA is a candidate material for rehabilitation of reinforced concrete structures.

On a Finger Model Actuated With Shape Memory Alloy Artificial Muscles

2003 ◽  
Author(s):  
Veturia Chiroiu ◽  
Ligia Munteanu ◽  
Traian Badea ◽  
Cornel Mihai Nicolescu
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Aluminum Matrix ◽  
Electrical Current ◽  
Longitudinal Axis ◽  
Damping Capacity ◽  
Artificial Muscles ◽  
Niti Wires ◽  
Finger Model ◽  
Start Temperature

The simulation of a flexible finger, actuated with the shape memory alloys (SMAs) artificial muscles, is presented in the paper. The finger is modeled as a cylindrically rod with three embedded NiTi wires in a n aluminum matrix. Forces between NiTi wires causes bending in any plane perpendicular to the longitudinal axis of the finger. The NiTi wires are heated above the austenitic start temperature by passing an electrical current, and the deflected wire tends to return to the initial configuration. Using characteristics of SMAs such as high damping capacity, super-elasticity, thermo-mechanical behavior and shape memory, the actuation for the finger is theoretically introduced and discussed.

scholarly journals Numerical Evaluation of Bond Behavior of Ribbed Steel Bars or Seven-wire Strands Embedded in Lightweight Concrete

2020 ◽  
Author(s):  
Mohammed A. Abed ◽  
Zaher Alkurdi ◽  
Ahmad Kheshfeh ◽  
Tamás Kovács ◽  
Salem Nehme
Keyword(s):  
Reinforced Concrete ◽  
Crack Width ◽  
Lightweight Concrete ◽  
Reinforced Concrete Structures ◽  
Bond Slip ◽  
Bond Behavior ◽  
Pull Out ◽  
Steel Bars ◽  
Maximum Crack ◽  
3D Software

The bond-slip relationship between concrete and steel is significant in evaluating the nonlinear behavior of reinforced concrete structures. The force transmitted by the bond in reinforced concrete structures was studied numerically in high-strength, lightweight concrete with ribbed reinforcing steel bar or seven-wire strand, using ATENA 3D software. The first part of the study was a validation of the model based on the actual results of standardized pull-out tests using the software. Subsequently, the bond behavior was studied, where a four-point static bending test was modeled based on the real bond-slip relationship of the pull-out test. It was deduced that the ATENA 3D software can simulate the experimental tests and provide meaningful results. In addition, inferred from the numerical modeling, the maximum crack width and the mid-span deflection of the reinforced concrete beam increased when the bond stress between the concrete and the reinforcing steel bars was decreased. When a high amount of reinforcement (two strands) was used, concrete failure occurred before the strands yielded. However, further increase of the bond stress also decreased the maximum crack width and mid-span deflection. The failure occurred due to the increase in the strand yielding point by using one strand as a reinforcement of the beam.

Shape Memory Alloy As Artificial Muscles for Facial Prosthesis

2017 ◽  
Author(s):  
Paul Mazza ◽  
Moochul Shin ◽  
Anthony Santamaria
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Response Times ◽  
Electrical Current ◽  
Artificial Muscles ◽  
Elliptical Equation ◽  
Facial Motion ◽  
Facial Prosthesis ◽  
Nitinol Wire ◽  
Original Length

Facial paralysis affects hundreds of thousands of people each year; a common result of infection, trauma, stroke, and Bell’s palsy, among others. Achieving facial prosthetics that are lightweight, comfortable, aesthetically pleasing, energy efficient, and that allow human-like facial motion is a challenge. This study focuses on examining the feasibility of the use of a shape memory alloy as a means of low-power artificial muscles. Nitinol is a shape memory alloy (SMA) that can recover up to four percent of its original length when exposed to either a large enough change in temperature which can be controlled via electrical current or a stress. In this work, human eyelid muscles are replicated using Nitinol embedded in silicon. Silicone is used due to its elasticity, texture, flexibility, compatibility and ease of manufacturing. A mold is created based on human facial geometry around the orbital using a 3D printer. Based on average human eyelid dimensions, as well as the contraction properties of the Nitinol wire, an elliptical equation is used determine the length of wire required to completely close the eyelid from an open position. Temperature change of the system is controlled by modulating current through the resistive Nitinol wire. The contraction and expansion times of the eyelids are measured. The circuit is then optimized so that response times mimicked that of the human eyelid. Finally, based on the amount of times the average human blinks, the average daily power consumption is calculated. Future directions including miniaturization of the control system, bonding between SMA wires and silicone, and energy management are discussed.

Behavior of a simple concrete beam driven by shape memory alloy wires

2006 ◽  
Vol 15 (4) ◽  
pp. 1039-1046 ◽  
Author(s):  
Hui Li ◽  
Zhi-qiang Liu ◽  
Jin-ping Ou
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Concrete Beam
Sign in / Sign up

Export Citation Format

Share Document