scholarly journals Assessment of SMA Electrical Resistance Change during Cyclic Stretching with Small Elongation

Sensors ◽  
2021 ◽  
Vol 21 (20) ◽  
pp. 6804
Author(s):  
Sebastian Sławski ◽  
Marek Kciuk ◽  
Wojciech Klein

In this article, changes in NiTi alloy (Flexinol) electrical resistance during cyclic stretching with small elongation were investigated. A dedicated test stand consisting of motorized vertical test stand, force gauge, and electric resistance measuring device with an accuracy of 0.006 Ω was developed. A dedicated control algorithm was developed using LabVIEW software. Changes in electrical resistance were investigated for the 0.1 mm Flexinol wire with length of 120 mm. Testing was performed in the elongation range between 0.25% and 1.5% in martensite phase. Tested samples were subjected to 30 stretching cycles with a movement speed of 10 mm/min. Obtained results show that the cyclic stretching of Flexinol wire reduces its electrical resistance with each stretching cycle. Moreover, it was noted that changes in Flexinol electrical resistance during cycling stretching depend on the assumed elongation and number of the already performed stretching cycles. The observed electrical resistance change decreases with each stretching cycle. Thus, the observed changes are greater during the first stretching cycles. For elongations exceeding 1%, the Flexinol electrical resistance in the first stretching cycle increases. In each subsequent cycle, electrical resistance decreases, as in the case of the smallest value of assumed elongation. In almost all tested cases (except in the case with 1.5% of assumed elongation), Flexinol electrical resistance after 30 stretching cycles was smaller than before the test.

Author(s):  
Byoung-Joon Kim ◽  
Hae-A-Seul Shin ◽  
In-Suk Choi ◽  
Young-Chang Joo

Abstract The electrical resistance Cu film on flexible substrate was investigated in cyclic bending deformation. The electrical resistance of 1 µm thick Cu film on flexible substrate increased up to 120 % after 500,000 cycles in 1.1 % tensile bending strain. Crack and extrusion were observed due to the fatigue damage of metal film. Low bending strain did not cause any damage on metal film but higher bending strain resulted in severe electrical and mechanical damage. Thinner film showed higher fatigue resistance because of the better mechanical property of thin film. Cu film with NiCr under-layer showed poorer fatigue resistance in tensile bending mode. Ni capping layer did not improve the fatigue resistance of Cu film, but Al capping layer suppressed crack formation and lowered electrical resistance change. The NiCr under layer, Ni capping layer, and Al capping layer effect on electrical resistance change of Cu film was compared with Cu only sample.


RSC Advances ◽  
2015 ◽  
Vol 5 (39) ◽  
pp. 31074-31080 ◽  
Author(s):  
Shaodi Zheng ◽  
Jie Deng ◽  
Luqiong Yang ◽  
Danqi Ren ◽  
Wei Yang ◽  
...  

The electrical resistance change of highly extensible films consisting of a network of carbon blacks in high-density polyethylene, with different regularity of stacked lamellae, is investigated.


Author(s):  
Ismael Payo ◽  
J. L. Polo ◽  
Blanca Lopez ◽  
Diana Serrano ◽  
Antonio M. Rodríguez ◽  
...  

Abstract Conductive Hydrogels are soft materials which have been used by some researchers as resistive strain sensors in the last years. The electrical resistance change, when the sensor is stretched or compressed, is usually measured by the two-electrode method. This method is not always suitable to measure the electrical resistance of polymers-based materials, like hydrogels, because it could be highly influenced by the electrode/sample interface, as explained in this study. For this reason, a signal conditioning circuit, based on four-electrode impedance measurements, is proposed to measure the electrical resistance change when the gel is stretched or compressed. Experimental results show that the tested gels can be used as resistance force/pressure sensors with a quite linear behaviour.


2020 ◽  
Vol 20 (12) ◽  
pp. 7644-7652
Author(s):  
Khalid Marbou ◽  
Waqas Gil ◽  
Amal Al Ghaferi ◽  
Irfan Saadat ◽  
Khalid Alhammadi ◽  
...  

In hostile environments, sensing is critical for many industries such as chemical and oil/gas. Within this industry, the deposition of scales or minerals on various infrastructure components (e.g., pipelines) forms a reliability hazard that needs to be monitored. Therefore, the approach adopted in this study to tackle this issue relies on the use of real-time sensing of specific ions in brine, the natural trigger for ions deposition. In order to do so, electrochemical sensors based on carbon nanotubes (CNTs) are developed, taking advantage of their unique properties facilitated by different synthesis and fabrication methods. One of these promising synthesis methods is inkjet printing of CNT films since in general, it has exceptional benefits over other approaches that are used to print CNTs. Furthermore, it does not need the use templates. In addition, it is a very fast technique with consistent printing results for many applications along with very low cost on various shapes/formfactors. As these sensors are exposed to a hostile environment (chemical, temperature, etc.), the stability of the CNT films is of great importance. In this study, a comprehensive investigation of the stability of CNT surfaces upon exposure to elements is presented. Accordingly, the several impacts of this interaction on physical properties of the surfaces as a function of interaction time and brine chemical composition are assessed. Moreover, the approach used for investigating the impact of this exposure involves the following: surface electrical resistance change using four probe measurements; surface roughness/topography using Atomic Force Microscopy (AFM) along Scanning Electron Microscopy (SEM); quality of CNT through Raman spectroscopy and wettability using the sessile drop method. The sensing capabilities of the devices are investigated by looking at the sensing selectivity of target ions, resetting capabilities, and sensing sensitivity manifested in the electrical resistance change. Consequently, our results indicate that while inkjet films are very promising sensor material, the fabrication and long term stability require further optimization of the films along with the process to make them meet reliability and lifetime requirements in the oil/gas hostile operational environments.


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