Bond behavior of NiTiNb SMA wires embedded in CFRP composites

Abstract

This article summarizes the details of an experimental and analytical program that was conducted to study the bond behavior between nickel‐titanium‐niobium shape memory alloy wires and fiber reinforced polymer composites. Understanding this bond behavior will facilitate the design of composite systems that are fabricated using both materials and which would exhibit unique properties that cannot be achieved using either material separately. A total of nine pull‐out specimens were fabricated and tested. A digital image correlation (DIC) noncontact measurement system was used to identify the onset and propagation of the debonding. The experimental results indicated that the interfacial bond transfer consists of two components: cohesion (before the onset of debonding) and friction (after the onset of debonding). A 3‐D nonlinear finite element analysis (FEA) was conducted to investigate the debonding mechanism of the pull‐out specimens. A trilinear cohesive zone model was used to model the interface taking into account the cohesive and friction components of the stress transfer at the interface. The debonding mechanism predicted by the FEA matches the experimental observations that were obtained using conventional instruments and the DIC system, well. POLYM. COMPOS., 39:3780–3791, 2018. © 2017 Society of Plastics Engineers

Experimental investigation on debonding behavior of Fe-SMA-to-steel joints

“…A trilinear bond-slip behavior is processed from every Fe-SMA-tosteel lap-shear joint with nonlinear adhesive. Such a trilinear bond-slip was also reported by Schranz et al [53] and El-Tahan et al [54], where pull-out tests were conducted on Fe-SMA rebars embedded in concrete blocks and Nickel-Titanium-SMA wires embedded in CFRP composites, respectively. In these studies, friction and mechanical interlock are believed to form the third branch of the bond-slip behavior.…”

Prestressed CFRP-strengthening and long-term wireless monitoring of an old roadway metallic bridge

“…Furthermore, Hosseini et al have developed the concept of PUR systems for fatigue strengthening of tensile steel members [22,23]. More recently, some studies (e.g., [15,[24][25][26]) on the application of shape memory alloys (SMAs) for the prestressed strengthening of steel plates have shown a promising future for this material. The SMA retrofit elements can be prestressed by thermal activation of the alloy [26].…”

“…Most existing studies on this topic have used a bonded retrofit (BR) system to attach the CFRP material to steel substrates (e.g., [11][12][13][14][15][16]). Despite extensive laboratory studies of BR systems, in practice, the CFRP strengthening of metallic bridges has not advanced by much.…”

Ultimate Bearing Capacity Analysis of CFRP-Strengthened Shield Segments Using Bonding Slip Behavior Experiments

“…Moreover, direct pull-out tests, which indicate that CFRP bars are embedded in concrete, showed a decrease of 12% in the ultimate bearing capacity caused by wet-dry cycles, with similar characteristic results for the "fish-spine" crack pattern. In addition, the bonding behavior [21,22] of concrete with CFRP under load and seawater wet-dry cycles where the entire liquid was 5% NaCl dropped from 85% to 60%. In contrast, in [23], the joints of the CFRP/steel under wet-freeze cycles showed no negative effect.…”

“…In this arrangement, the CFRP is subjected to eccentric tension, as shown in Figure 1 b [ 23 , 28 ]. The double-sided shear test refers to CFRP sheets bonded in the upper and lower surfaces of concrete, which is complicated to use in the existing tensile test machine, as shown in Figure 1 c [ 21 , 24 ]. Hamada and Fang [ 29 ] use the method of the bending shear experiment that is based on the bending experiment of the beam.…”