Effect of 3D, 4D, and 5D hooked-end type and loading rate on the pull-out performance of shape memory alloy fibres embedded in cementitious composites

2020 ◽  
pp. 121742
Author(s):  
Ayoub Dehghani ◽  
Farhad Aslani
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Loading Rate ◽  
Cementitious Composites ◽  
Pull Out

scholarly journals Experimental and Numerical Analysis of the Mechanical Properties of a Pretreated Shape Memory Alloy Wire in a Self-Centering Steel Brace

Processes ◽  
2021 ◽  
Vol 9 (1) ◽  
pp. 80
Author(s):  
Bo Zhang ◽  
Sizhi Zeng ◽  
Fenghua Tang ◽  
Shujun Hu ◽  
Qiang Zhou ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Elastic Modulus ◽  
Energy Dissipation ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Loading Rate ◽  
Effective Elastic Modulus ◽  
Maximum Energy ◽  
Numerical Results ◽  
Energy Dissipation Capacity

As a stimulus-sensitive material, the difference in composition, fabrication process, and influencing factors will have a great effect on the mechanical properties of a superelastic Ni-Ti shape memory alloy (SMA) wire, so the seismic performance of the self-centering steel brace with SMA wires may not be accurately obtained. In this paper, the cyclic tensile tests of a kind of SMA wire with a 1 mm diameter and special element composition were tested under multi-working conditions, which were pretreated by first tensioning to the 0.06 strain amplitude for 40 cycles, so the mechanical properties of the pretreated SMA wires can be simulated in detail. The accuracy of the numerical results with the improved model of Graesser’s theory was verified by a comparison to the experimental results. The experimental results show that the number of cycles has no significant effect on the mechanical properties of SMA wires after a certain number of cyclic tensile training. With the loading rate increasing, the pinch effect of the hysteresis curves will be enlarged, while the effective elastic modulus and slope of the transformation stresses in the process of loading and unloading are also increased, and the maximum energy dissipation capacity of the SMA wires appears at a loading rate of 0.675 mm/s. Moreover, with the initial strain increasing, the slope of the transformation stresses in the process of loading is increased, while the effective elastic modulus and slope of the transformation stresses in the process of unloading are decreased, and the maximum energy dissipation capacity appears at the initial strain of 0.0075. In addition, a good agreement between the test and numerical results is obtained by comparing with the hysteresis curves and energy dissipation values, so the numerical model is useful to predict the stress–strain relations at different stages. The test and numerical results will also provide a basis for the design of corresponding self-centering steel dampers.

scholarly journals Tests on Pretrained Superelastic NiTi Shape Memory Alloy Rods: Towards Application in Self-Centering Link Beams

2018 ◽  
Vol 2018 ◽  
pp. 1-13
Author(s):  
Xian Xu ◽  
Guangming Cheng ◽  
Junhua Zheng
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Strain Amplitude ◽  
Loading Rate ◽  
Mechanical Performance ◽  
Material Model ◽  
Niti Shape Memory Alloy ◽  
Test Results ◽  
Potential Applications ◽  
Strain Model

Austenitic shape memory alloy has potential applications in self-centering seismic resistant structural systems due to its superelastic response under cyclic tension. Raw austenitic SMA needs proper pretreatments and pretraining to gain a stable superelastic property. In this paper, tests are carried out to investigate the effects of pretraining, pretreatments, loading rate, and strain amplitude on the mechanical performance on austenitic SMA rods with a given size. The tested rods are to be used in a new concept self-centering steel link beam. Customized pretraining scheme and heat treatment are determined through the tests. The effects of loading rate and strain amplitude are investigated. A simplified stress-strain model for the SMA rods oriented to numerical simulations is obtained based on the test results. An example of using the simplified material model in numerical analysis of a self-centering steel link beam is conducted to validate the applicability of the model.

Micromechanics of stress transfer in shape memory alloy reinforced three-phase composites

2018 ◽  
Vol 29 (15) ◽  
pp. 3151-3164 ◽  
Author(s):  
Fathollah Taheri-Behrooz ◽  
Mohammad Javad Mahdavizade ◽  
Alireza Ostadrahimi
Keyword(s):  
Finite Element ◽  
Stress Distribution ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Thermal Loading ◽  
Hybrid Composites ◽  
Stress Transfer ◽  
Shape Memory Alloy Wire ◽  
Alloy Wire ◽  
Pull Out

Due to the weak interface in shape memory alloy wire–reinforced composites, the influence of interphase on the mechanical properties and stress distribution of hybrid composites is of considerable importance. In this article, a three-cylinder axisymmetric model using a pull-out test is developed to predict stress transfer and interfacial behavior between shape memory alloy wire, interphase, and matrix. In this article, only superelasticity behavior of the shape memory alloy wire is considered. Based on the stress function method and the principle of minimum complementary energy, stress distribution is derived for three different cases in terms of loading and boundary conditions (thermal loading model, intact model, and partially debonded model). Inhomogeneous interphase and different radial and hoop stress components in each phase are considered to achieve deeper physical understanding. Finite element analysis also performed to simulate stress transfer from the wire to the matrix through the interphase. To evaluate the accuracy of this model, the results of the work are compared with the results of the two-cylinder model proposed by Wang et al. and finite element results.

Design, Simulation and Testing of Shape Memory Alloy Actuator for Mixing Two Solutions in High-Pressure Optical Cell for Biophysical Studies

2006 ◽  
Author(s):  
Hongchun Xie ◽  
Jack Zhou ◽  
Parkson Chong
Keyword(s):  
High Pressure ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Nickel Titanium ◽  
Intensity Change ◽  
Optical Cell ◽  
Pull Out ◽  
Spring Force ◽  
Heat Response ◽  
Sma Spring

Window-type high-pressure optical cells (HPOC) such as the one designed by Paladini and Weber [Rev. Sci. Instrum. 52, (1981) p. 419] have provided biophysicists a powerful tool to understand the structure-function relationships of biological molecules. However, the conventional HPOC is only good for single solution testing and does not allow for quick mixing and stirring of additional components while the sample is under pressure. To mix two solutions under pressure, Zhou et al [Rev. Sci. Instrum. 69, (1998) p. 3958] developed a laser activated dual chamber HPOC. However, the expensive laser device and its unavailability in most laboratories make the application difficult. In a later study, Zhou et al. [Rev. Sci. Instrum. 71, (2000) p. 4249] introduced shape memory alloy (SMA) as an actuator to unplug a urethane stopper with a biasing spring for agitation. The drawback is that the biasing spring blocks the observing light beam and creates unwanted reflections. This research is to construct an actuator with concentric SMA spring and compressive biasing spring: an SMA helical tensile spring to pull out the stopper to let two solutions mix; and a helical compressive spring to bias and to agitate solutions, and to leave the lower half cuvette clear for optical observation. Due to the limited space in the cuvette, the alignment of two springs is critical for both motion and heat response to activate each spring separately. This paper discusses the design of SMA actuator, SMA spring testing and mixing testing by the SMA spring actuator. Since SMA (nickel-titanium) spring is not solderable and crimping method is limited due to the space, a conductive adhesive is used not only to fix the alignment between springs and cap, but also to conduct electric current. Spring force testing was done by INSTRON. Mixing testing used flourescein intensity change to trace the mixing process. The bio-compatibility of the nickel-titanium SMA with proteins and phospholipids has also been tested.

scholarly journals Experimental and Finite Elements Analysis Study of Warming Effect on Deboned Force for Embedded NiTinol Wire into Linear Low Density Polyethylene

2018 ◽  
Vol 14 (4) ◽  
pp. 1-8
Author(s):  
Samir Ali Amin ◽  
Ali Yasser Hassan
Keyword(s):  
Shear Stress ◽  
Finite Elements ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Low Density Polyethylene ◽  
Low Density ◽  
Linear Low Density Polyethylene ◽  
Finite Elements Analysis ◽  
Pull Out ◽  
Nitinol Wire

This study presents the debonding propagation in single NiTi wire shape memory alloy into linear low-density polyethylene matrix composite the study of using the pull-out test. The aim of this study is to investigate the pull-out tests to check the interfacial strength of the polymer composite in two cases, with activation NiTinol wire and without activation. In this study, shape memory alloy NiTinol wire 2 mm diameter and linear fully annealed straight shape were used. The study involved experimental and finite element analysis and eventually comparison between them. This pull-out test is considered a substantial test because its results have a relation with behavior of smart composite materials. The pull-out test was carried out by a universal tensile test machine type (Laryee), load capacity (50 kN), and a test speed of 1mm/min. The finite elements modeling was performed by ANSYS V.15. The results of pull-out test showed that in the activation of NiTinol wire embedded in host matrix linear low-density polyethylene (LLDPE), the deboned force was about 74 N, but for the case without activation, it was about 106 N. Deboned shear stress for the case with activation was about 0.73 MPa, but for the case of without activation, it was about 1.05 MPa. ANSYS result for deboned shear stress in case with activation was about 0.8 MPa. As for the case of without activation, deboned shear stress was about 0.99 MPa. The activation of the ratio of deboned shear stress and deboned force decreased by 30.47% and 30.13%, respectively. The error ratio between experimental and ANSYS results was equal to 8% for the case with activation and 5.7% for the case without activation. 

scholarly journals Finite Element Simulation of NiTiNb Shape Memory Alloy Pipe-Joint Subjected to Coupled Transformation and Plastic Deformation

2020 ◽  
Vol 2020 ◽  
pp. 1-14
Author(s):  
Xiang Chen ◽  
Bin Chen ◽  
Xianghe Peng ◽  
Xiaoqing Jin ◽  
Ying Ma ◽  
...  
Keyword(s):  
Plastic Deformation ◽  
Phase Transformation ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
High Performance ◽  
Coupling Effect ◽  
Longitudinal Direction ◽  
Design Parameters ◽  
Pull Out ◽  
Pipe Joint

The assembling process of Ni47Ti44Nb9 alloy pipe joints considering the phase transformation and plasticity was numerically simulated for the first time with a developed constitutive model. The simulated process was based on the experimental material parameters, which were determined with the experimental tensile results of Ni47Ti44Nb9 shape memory alloy (SMA) and steel bars. The results showed that, after assembly, the Mises stress distributed uniformly along the longitudinal direction of the NiTiNb joint, but nonuniformly along the radial direction. The maximum σeq does not appear at the inner wall of the joints due to the coupling effect of the plastic deformation and the recoverable transformation. The contact pressure distributed uniformly along the circumferential direction, but nonuniformly along the longitudinal direction. The sizes of the SMA joint and the pipe should be properly matched to ensure contact during the stage of the rapid reverse phase transformation to obtain stable connection performance. The pull-out force was also computed, and the results were in good agreement with the experimental results. The results obtained can provide available information for the optimization of the design parameters of the high-performance SMA pipe-joint, such as inner diameter and assembly clearance.

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