Experimental assessment of self-healing nature in aluminum-based smart composites with NiTi wires and solder alloy as healing agents through Taguchi approach

2020 ◽  
Vol 31 (18) ◽  
pp. 2101-2116 ◽  
Author(s):  
Vaibhav Srivastava ◽  
Manish Gupta
Keyword(s):  
Heat Treatment ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Solder Alloy ◽  
Crack Depth ◽  
Self Healing ◽  
Flexural Testing ◽  
The Matrix ◽  
Healing Temperature ◽  
Niti Wires

In this article, the healing assessment of the AA2014 matrix reinforced with NiTi wires and solder alloy as healing agents is investigated through flexural testing. The idea of a smart composite was such that it could retain its structural stability through NiTi wires reinforced, which ultimately heals the macro cracks, whereas the solder alloy binds the micro-cracks by filling through the gap after heat treatment. The objective of this work is to determine the parameters influencing self-healing assessments. Specimens with different shape memory alloy vol% (0.5%, 1.3%), specimen size (1, 2) and shape memory alloy wires diameter (0.47 mm, 0.96 mm) were fabricated for analysis. Furthermore, Taguchi orthogonal columns of L8 (4^1 2^3) array technique was implemented to study the observations from different experimental runs. Healing temperature (i.e. 600°C) was selected such that it could take advantage of the compositional healing of the matrix. The completely damaged specimens through the bend test were thermally treated at different healing durations (30, 60, 90, 120 min) in a furnace to activate healing. The results show that a maximum of 96.95% of crack depth, 100% of crack width, and 73.76% of the recovery in flexural strength was recovered after heat treatment.

Optimal design of a bio-inspired self-healing metal matrix composite reinforced with NiTi shape memory alloy strips

2018 ◽  
Vol 29 (20) ◽  
pp. 3972-3982 ◽  
Author(s):  
Mohammad Amin Poormir ◽  
Seyed Mohammad Reza Khalili ◽  
Reza Eslami-Farsani
Keyword(s):  
Mechanical Properties ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Metal Matrix Composite ◽  
Matrix Composite ◽  
Smart Materials ◽  
Metal Matrix ◽  
Self Healing ◽  
Healing Temperature ◽  
Design Factors

Utilizing smart materials such as shape memory alloys as reinforcement in metal matrix composites is a novel method to bio-mimic self-healing. This study aims to investigate the influence of design factors of a self-healing metal matrix composite by employing the Taguchi method for designing of the experimental procedure. Three design factors, each in three levels, were studied simultaneously according to L-9 standard Taguchi orthogonal array to determine the optimal level of each factor in mechanical properties enhancement with a reduced number of experiments. Composite specimens were fabricated from Sn-13 wt.% Bi alloy as matrix and nickel–titanium shape memory alloy strips as reinforcement with gravity casting process. Matrix alloy was melted and casted in a preheated metallic mold in which SMA strips were installed in various quantities (one, two, or three strips) and different pre-strains (0%, 2%, or 6%). After fabrication of the specimens, a tensile test was conducted until fracture to specify mechanical properties. Then, specimens were placed in a furnace in three different temperatures (170°C, 180°C, and 190°C) to activate the shape memory effect of strips and achieve crack closure and healing. Specimens were tensile tested again after healing to calculate the amount of healed properties and healing efficiency. Results show that using three strips with 6% of pre-strain and applying 190°C healing temperature can maximize the ultimate tensile strength efficiency. Also, the existence of one strip, 0% pre-strain, and 190°C healing temperature creates the best circumstances for healing ductility.

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.

Shear Load Transfer in Shape Memory Alloy Fiber Reinforced Composites During Elastic Axisymmetric Deformations

2000 ◽  
Author(s):  
Hungyu Tsai ◽  
Xinjian Fan
Keyword(s):  
Phase Transformation ◽  
Stress Concentration ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Transition Layer ◽  
Load Transfer ◽  
Fiber Reinforced Composites ◽  
Shear Load ◽  
Reinforced Composites ◽  
The Matrix

Abstract The axisymmetric elastic deformations in shape memory alloy (SMA) fiber reinforced composites are studied. We analyze the stress concentration near the interface between the fiber and the matrix as a result of a pre-described phase transformation in the active fiber. A typical model involving a single infinite fiber embedded in an infinite elastic matrix is studied. A portion of the fiber is allowed to undergo phase transformation along the axial direction so that its length is changed by the corresponding transformation strain (typically a few percentages), while the matrix is assumed to be linearly elastic and isotropic. Under certain bonding conditions, the deformation of fiber forces the matrix to deform in the elastic regime in order to accommodate the transformation strains. The problem is formulated as axisymmetric deformations coupled with a finite transformation region in the fiber. In order to avoid infinite stresses found under perfect bonding conditions, we adopt a “spring” model which accounts for the elasticity of a transition layer at the interface. This model allows for relative displacements between the fiber and the matrix. A linear relation between this relative displacement and the shear stress is used. The exact elasticity solution (in integral form) to this problem is found using Love’s stress function and Fourier transform. Numerical integration is performed to produce the stress distributions. In particular, the shear load transfer profiles along the interface are calculated for various spring stiffness. It is found that the singularity is eliminated and the stress concentration factor depends on the stiffness of the transition layer.

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