Improvement in separation of SMA from matrix in SMA embedded smart structures

Umezaki, Eisaku

doi:10.1016/s0921-5093(00)00693-6

Cited by 18 publications

(10 citation statements)

References 3 publications

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“…It has been recommended that the working temperature of the Ni-Ti SMA actuator should not exceed the glass transition temperature (T g ) of the matrix material. To avoid this, intermittent supply of electric current during heating, the SMA is recommended (Umezaki, 2000).…”

Section: Methods For Arresting/healing Cracks In Polymeric Compositesmentioning

confidence: 99%

Development and testing of an intelligent hybrid polymeric composite beam embedded with Ni-Ti shape memory alloy with crack growth retarding ability

Mwita¹,

Mtawa²

2012

Sci. Res. Essays

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Hybrid Polymeric Composites (HPC) structural materials pose a challenge of developing microcracks and delaminations under impact and dynamic loads. This paper presents the development and testing of an Intelligent Hybrid Polymeric Composite (IHPC) beam embedded with Ni-Ti Shape Memory Alloy (SMA) with crack growth retarding ability. Upon heating to austenite finish temperature (A f), Ni-Ti SMA wire contracts as a result of detwinned martensite-austenite phase transformation. The contraction of the SMA was utilized to stiffen and retard crack growth in the IHPC beam, hence resulting to an increase of mode I fracture stress intensity factor (K IC). The SMA wire specimens were aged at 250°C, then prestrained at 3% in order to stabilize austenite start (A s) and austenite finish (A f) transformation temperatures. The values of A s and A f for Ni-Ti SMA were determined. The IHPC and Polymeric Virgin (PV) notched beams were fabricated from epoxy resin. A four point bending test was performed on the beams to determine the effect of actuated Ni-Ti SMA on mode I fracture stress intensity factor K IC. The test was done at two temperatures, at T1 (below A s) and at T2 (A f). Results showed that actuation of the Ni-Ti SMA increased the value of K IC for IHPC beams at T2 by 189% over the value of K IC for PV beams at T1. Actuation of the Ni-Ti SMA increased the value of K IC for IHPC beams at T2 by 41% over the value of K IC for IHPC beams at T1. Results showed that at T1 the loaded PV and IHPC beams fractured with unsteady crack propagation, while at T2 the loaded IHPC beams fractured with steady crack propagation. An increased value of K IC and steady crack propagation at T2 indicated that the SMA improved the crack retarding ability of the HPC beam.

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Section: Methods For Arresting/healing Cracks In Polymeric Compositesmentioning

confidence: 99%

Development and testing of an intelligent hybrid polymeric composite beam embedded with Ni-Ti shape memory alloy with crack growth retarding ability

Mwita¹,

Mtawa²

2012

Sci. Res. Essays

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show abstract

“…In addition to the confinement and pre-stressing effects obtained through SMA wire application, the self-crack closing behavior of composites reinforced with SMA wire has also been investigated. SMA wires added to epoxy or cement mortar were applied to generate a crack closing capability in a beam [18,19,20]. In order to create the crack closing ability, it is important to have a strong interfacial bond strength between the fiber or wire and the surrounding matrix.…”

Section: Introductionmentioning

confidence: 99%

“…In order to create the crack closing ability, it is important to have a strong interfacial bond strength between the fiber or wire and the surrounding matrix. Accordingly, Umezaki [18] investigated the pullout resistance of SMA wires, reporting that spiral SMA wires produced a higher pullout resistance than smooth SMA wires. Wang et al [21] investigated the internal stress distribution to prevent debonding at the SMA fiber and epoxy matrix interface, in order to eventually utilize the shape memory effect more efficiently.…”

Section: Introductionmentioning

confidence: 99%

Effects of a Short Heat Treatment Period on the Pullout Resistance of Shape Memory Alloy Fibers in Mortar

Kim

Chung

et al. 2019

Materials

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The feasibility of the crack closure of cementitious composites reinforced with shape memory alloy (SMA) fibers was investigated by performing single-fiber pullout tests. To demonstrate the fast crack closing ability, in this study, a heat treatment (300 °C) was applied for a short time (10 min). A short heat treatment was applied for 10 min, after the slip reached 0.5 mm, to activate the shape memory effects of cold-drawn SMA fibers. Two types of alloys were investigated, NiTi and NiTiNb, with two geometries, either smooth or dog-bone-shaped. During the heat treatment, the pullout stress of the SMA fibers initially decreased due to thermal extension, and then increased after heating for 1–3 min, resulting from the shape memory effects. However, their pullout stress recovery during and after the heat treatment was different for the different alloys and fiber geometries. The NiTi fibers generally produced a higher and faster recovery in terms of their pullout stress than the NiTiNb fibers, while the dog-bone-shaped fibers showed a faster pullout stress recovery than the smooth fibers.

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“…However, the utilization of SMA wires as actuators is often limited by the weak interface between SMA fiber and matrix. Researchers have therefore undertaken much experimental work to improve interfacial adhesion by mechanical or chemical methods [11][12][13]. Stress transfer during the SMA fiber pull-out has also been studied theoretically.…”

Section: Introductionmentioning

confidence: 99%

Analysis of internal stresses induced by strain recovery in a single SMA fiber–matrix composite

Wang

Zhou

Wang

et al. 2011

Composites Part B: Engineering

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Improvement in separation of SMA from matrix in SMA embedded smart structures

Cited by 18 publications

References 3 publications

Development and testing of an intelligent hybrid polymeric composite beam embedded with Ni-Ti shape memory alloy with crack growth retarding ability

Development and testing of an intelligent hybrid polymeric composite beam embedded with Ni-Ti shape memory alloy with crack growth retarding ability

Effects of a Short Heat Treatment Period on the Pullout Resistance of Shape Memory Alloy Fibers in Mortar

Analysis of internal stresses induced by strain recovery in a single SMA fiber–matrix composite

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