Effect of tensile loading rate on interfacial properties of SMA/polymer composites

Fathi, Hamidreza; Shokrieh, M.M.; Saeedi, Ali

doi:10.1016/j.compositesb.2019.107730

Cited by 10 publications

(11 citation statements)

References 23 publications

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“…In order to induce a similar stress state in all SMA wire configurations and to ensure the comparability of the results, the mechanically induced pull-out test was performed, which corresponds to the state of the art. ,,, In the case of the thermally activated pull-out test, the stress distribution at the interface has not yet been understood as the transformation behavior, and thus the contraction of the SMA wire, is not homogeneous. , …”

Section: Materials and Methodsmentioning

confidence: 99%

Electrochemical Surface Structuring for Strong SMA Wire–Polymer Interface Adhesion

Gapeeva

Vogtmann

Zeller‐Plumhoff

et al. 2021

ACS Appl. Mater. Interfaces

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Active hybrid composites represent a novel class of smart materials used to design morphing surfaces, opening up new applications in the aircraft and automotive industries. The bending of the active hybrid composite is induced by the contraction of electrically activated shape memory alloy (SMA) wires, which are placed with an offset to the neutral axis of the composite. Therefore, the adhesion strength between the SMA wire and the surrounding polymer matrix is crucial to the load transfer and the functionality of the composite. Thus, the interface adhesion strength is of great importance for the performance and the actuation potential of active hybrid composites. In this work, the surface of a commercially available one-way effect NiTi SMA wire with a diameter of 1 mm was structured by selective electrochemical etching that preferably starts at defect sites, leaving the most thermodynamically stable surfaces of the wire intact. The created etch pits lead to an increase in the surface area of the wire and a mechanical interlocking with the polymer, resulting in a combination of adhesive and cohesive failure modes after a pull-out test. Consequently, the force of the first failure determined by an optical stress measurement was increased by more than 3 times when compared to the as-delivered SMA wire. The actuation characterization test showed that approximately the same work capacity could be retrieved from structured SMA wires. Moreover, structured SMA wires exhibited the same shape of the stress−strain curve as the as-delivered SMA wire, and the mechanical performance was not influenced by the structuring process. The austenite start A s and austenite finish A f transformation temperatures were also not found to be affected by the structuring process. The formation of etching pits with different geometries and densities was discussed with regard to the kinetics of oxide formation and dissolution.

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Section: Materials and Methodsmentioning

confidence: 99%

Electrochemical Surface Structuring for Strong SMA Wire–Polymer Interface Adhesion

Gapeeva

Vogtmann

Zeller‐Plumhoff

et al. 2021

ACS Appl. Mater. Interfaces

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“…It is found from Figure 4b that the predicted tensile strength are slightly higher than the experimental values at high temperatures compared with Figure 4a. This is due to the fact that the material is more susceptible to the crack growth at high loading rates, resulting in degradation of interfacial properties 57,58 . The present model does not account for the strain rate effect directly, and thus leads to the higher predicted results.…”

Section: Resultsmentioning

confidence: 89%

“…This is due to the fact that the material is more susceptible to the crack growth at high loading rates, resulting in degradation of interfacial properties. 57,58 The present model does not account for the strain rate effect directly, and thus leads to the higher predicted results. In general, the comparison results show that when the tensile strength decreases by 90% with increasing temperature, our model can still accurately predict the tensile strengths at high temperatures.…”

Section: Peek Based Smp Prepared By Zhuang Jingdong Huazhong Universi...mentioning

confidence: 88%

Temperature dependent tensile strength modeling and analysis of shape memory polymers with physics‐based energy equivalence principle

Zhang

Zuo

et al. 2023

J of Applied Polymer Sci

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The quantitative characterization of the tensile strength of shape memory polymers (SMPs) at different temperatures has always been an important research topic. In this study, the critical failure energy density of SMPs including the strain energy density, potential energy and kinetic energy of atomic motion per unit volume is first introduced. Then, based on the equivalent contribution of these energies on material failure, a temperature dependent tensile strength (TDTS) model considering the corresponding physical mechanism for SMPs is established. The model provides the quantitative relationship among temperature, Young's modulus, hardening index and the tensile strength of SMPs.Meanwhile, the predicted results of the proposed model are compared with the available TDTS of SMPs, and the agreement between theory and experiment is satisfactory. In addition, the influencing factors of tensile strength and their variation with temperature are analyzed. This work contributes the novel insight for the theoretical predictions on the TDTS of SMPs, which is helpful for the high temperature strength evaluation and property optimization.

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“…[5][6][7] The most widely adopted test is a mechanically induced pull-out test with an external force pulling out the embedded SMA wire. [8][9][10][11] However, in this test, the influence of temperature during activation of the SMA wire and the resulting nonlinear stress-strain characteristics during phase transformation of the SMA wire are not considered. In contrast, in an in situ thermally induced pull-out test, the SMA wire generates the pull-out force itself upon heating above its phase transition temperature.…”

Section: Introductionmentioning

confidence: 99%

Pull‐Out Testing of Electrochemically Etched NiTi Shape Memory Alloy Wires in Shape Memory Alloy Hybrid Composites

Gapeeva,

Jungbluth,

Zeller‐Plumhoff

et al. 2024

Adv Eng Mater

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This study presents an experimental characterization of the interface strength of the shape memory alloy hybrid composite (SMAHC) consisting of the two‐way effect NiTi shape memory alloy (SMA) wire structured by electrochemical etching and the surrounding thermoset matrix. Mechanically induced, in situ thermally induced, and cyclic load‐increase pull‐out tests consistently reveal that SMAHC with structured SMA wires outperforms those with as‐delivered SMA wires by a substantial factor of 2.6 to 2.7 in interfacial strength — the critical factor governing the overall performance and functionality of the composite. Analyzing the force‐displacement curves from mechanically induced pull‐out tests demonstrates that structuring the SMA wire surface leads to a significantly increased elastic energy to initiate a crack and achieve complete failure. SMA wires with structured surfaces continue transferring load even after the initial interfacial failure due to the presence of intact mechanical interlocking sites. The cyclic load‐increase pull‐out test confirms that SMA wires with structured surfaces exhibit a significantly higher load‐bearing capacity, withstanding more load levels and demonstrating greater force of the first failure. Furthermore, in thermally induced pull‐out tests with structured SMA wires, a re‐initiation of failure from the lower side follows an initial failure progression at the SMA wire entry point.This article is protected by copyright. All rights reserved.

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Effect of tensile loading rate on interfacial properties of SMA/polymer composites

Cited by 10 publications

References 23 publications

Electrochemical Surface Structuring for Strong SMA Wire–Polymer Interface Adhesion

Electrochemical Surface Structuring for Strong SMA Wire–Polymer Interface Adhesion

Temperature dependent tensile strength modeling and analysis of shape memory polymers with physics‐based energy equivalence principle

Pull‐Out Testing of Electrochemically Etched NiTi Shape Memory Alloy Wires in Shape Memory Alloy Hybrid Composites

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