Experimental Investigation on the Cyclic Compression Behavior of Superelastic NiTi SMA Bars

Author(s):  
Amedebrhan M. Asfaw ◽  
Guohua Xing ◽  
Osman E. Ozbulut

Abstract Over the past decade, shape memory alloy (SMA) in the form of wires and cables have been extensively studied for various structural engineering applications. There are numerous application areas where pure compression (or coupled with tension) is the primary load bearing scenario, which requires larger size SMA bars. However, the compression behavior of SMA bars is not well known, and little is reported in the literature. In that perspective, this paper presents an experimental study on large diameter superelastic Nickel-Titanium (NiTi) bars subjected to a cyclic compression load. A total of nine SMA bars having slenderness ratios ranging from 60 to 90 were tested. Hysteretic stress-strain responses are plotted and critical buckling load, energy dissipation and residual strain of SMA bars with different slenderness ratios are presented.

Author(s):  
Maiid Tabesh ◽  
Mohammad Elahinia

Shape Memory Alloys, such as Nickel Titanium, undergo a phase transformation in their crystalline structure when transformed from Austenite into Martensite. This inherent phase transformation is the basis for the unique properties of shape memory and superelasticity. Shape memory is attributed to the recovery of large mechanically induced deformations upon raising the temperature upto a specific level (Af). The superelasticity is the ability of the material, at a temperature above Austenite start Af, to recover mechanical deformations upon unloading. Thanks to superelasticity, shape memory effect, high damping capacity, corrosion resistance and biocompatibility, NiTi SMA alloys gain researchers attention for implementation in biomedical fields for the past 40 years [1].


Author(s):  
Shinobu Kaneda ◽  
Hirokazu Tsuji

In the past study the plastic region tightening has been applied to the bolted flange joint with smaller nominal diameter and its advantages have been demonstrated, however, behavior of the bolted flange joint with larger diameter is not investigated. Flange rotation of the bolted flange joint with large diameter increases when the internal pressure is applied. Gasket stress is not uniform and it may cause leak accident. So, it is necessary to investigate the behavior of the larger diameter flange. The present paper describes the behavior of bolted flange joint with large diameter under plastic region tightening. Firstly, API 20-inch flange joint tightened to the plastic region by bolt with a smaller diameter and superiority in the uniformity of the axial bolt force is demonstrated. And then the internal pressure is applied to the bolted flange joint and the behavior of the additional axial bolt force is demonstrated. The axial bolt force decreases with increasing the internal pressure, and the load factor is negative due to increasing of the flange rotation. However, the load factor of the bolted flange joint tightened to the plastic region by using the bolt with the smaller diameter approached zero. Using the bolts with smaller diameter is advantageous to the flange joint with the larger diamter, whose load factor is negative, to prevent the leakage. Additionally, the leak rate from the bolted flange joint is measured and the sufficient sealing performance is obtained.


Author(s):  
Rijk Block ◽  
Barbara Kuit ◽  
Torsten Schröder ◽  
Patrick Teuffel

<p>The structural engineering community has a strong responsibility to contribute to a more efficient use of natural resources. Nowadays the construction industry is by far the most resource intense industry sector, approximately 40-50% of all primary raw materials are used, which raises the question about the architects and engineer’s accountability. In this context and as a result of the Paris Climate agreement the Dutch government defined the program “Nederland Circulair in 2050”, which states the ambition to use 50% less primary materials in 2030 and to have a full circular economy in 2050.</p><p>One possible approach to achieve these ambitious goals is the application of renewable, bio-based materials in the built environment and to replace traditional, typically cement-based, materials. Already in the past natural building materials, such as timber and bamboo have been used widely, but in recent years new materials came up and provide new opportunities to be used in the construction industry. The authors explored various alternatives, such as hemp and flax fibres, mycelium and lignin-based fibres for composite materials, which will be described with various experimental and realised case studies.</p>


2021 ◽  
Vol 73 (06) ◽  
pp. 41-41
Author(s):  
Alex Crabtree

Last year, this feature opened, almost inevitably, with comments on the effects the COVID-19 pandemic might have on our industry. Unfortunately, a year later, we probably have all experienced the effects, both personal and work-related. One of these effects is that there has been re-evaluation of what’s important. To understand what is important takes some reflection and evaluation of the past. In previous features, the focus has been on what is new or reimagined. Therefore, I thought that, in selecting papers for this year’s feature, it would be useful to select ones that look at coiled tubing operations performed and that have been evaluated in one way or another. From Bolivia comes a paper that reviews some 25 well interventions performed. Most of these operations are of a type that will be familiar to the reader. Also, some of the challenges that were faced in performing these coiled tubing operations will be familiar. These operations used a range of established types of coiled tubing operations and blended the techniques to meet particular operating conditions, especially location and logistics challenges. All conclusions and best practices that resulted, however, may not be familiar to all readers. During the past few years, many coiled tubing papers have focused on the use of coiled tubing in multizone fracturing operations, especially plug milling. An area of coiled tubing use in fracturing operations that has had less of an audience recently has been the use of coiled tubing in annular fracturing operations. This activity is still routinely being performed, particularly in Canada. The question has long existed about how the pipe is being eroded. In the related paper in this feature, the authors explain how they have tried to answer that question and have shared some of their review insights. In the past decade, coiled tubing size, weight, and grade all have continued to increase. Looking back at this trend and thinking about its effect on pressure control equipment led the developers in the third of this year’s papers to work on solutions for shear rams. This is particularly relevant after having just passed the 11th anniversary of the tragic Macondo disaster. Again, this year, I ask everyone to stay well. Recommended additional reading at OnePetro: www.onepetro.org. OTC 30408 Design and Safety Considerations To Perform Coiled Tubing Operations in Large-Diameter, High-Temperature Geothermal Wells by Ishaan Singh, Schlumberger, et al. SPE 204446 Implementing Business Analytics Software To Optimize Coiled Tubing Operations: A Digital Approach to Operations Efficiency by Xaymaca Bautista Alarcon, Royal Oaks Energy Services, et al. SPE 203272 The Reinvention of a Well-Established Coiled Tubing Intervention Work Flow Creates New Perspectives for Acidizing Openhole Horizontal Tight Carbonate Water Injectors by Sameer Punnapala, ADNOC, et al.


Author(s):  
Wenwei Zhang ◽  
Zhenyong Zhang ◽  
Jinyuan Zhang ◽  
Peng Yang

China National Petroleum Corporation (CNPC) has constructed large-diameter high-strength pipelines (X70 and X80) in the past decades in areas of seismic activities, mine subsidence, and slope movement using strain-based design (SBD) technology. More pipelines being constructed now traverse regions of active seismic activities, mine subsidence, slope movement, and discontinuous permafrost. CNPC is also interested in moving to linepipe grades higher than X80. In view of the recent development of various tensile strain models, work was undertaken to evaluate those models and determine the most appropriate models for current and future applications. In this paper, selected tensile strain models are reviewed and evaluated against an experimental database. The database of 80 tests from public-domain publications contains both full-scale pipe tests and curved wide plate tests with 46 tests from high strength pipes (X80 and above). The calculated tensile strain capacity from the selected models was compared with the test data. The models were evaluated and the applicability of the models to the linepipes of different strength levels was discussed.


Materials ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 3845
Author(s):  
Eunsoo Choi ◽  
Ha Vinh Ho ◽  
Jong-Su Jeon

This study investigated the recovery stress and bond resistance of cold drawn crimped SMA fiber using two different initial diameters of 1.0 and 0.7 mm. These characteristics are important to the active prestressing effect and crack-closing of the fiber. NiTi SMA fiber was used for the cold drawing, and then crimped shapes were manufactured with various wave heights. After that, tensile, recovery, and pullout tests were conducted. The cold drawn crimped fiber showed softening tensile behavior more clearly than the cold drawn straight fiber when not subjected to heating, whereas they had the same tensile behavior under heating. The recovery stress and the residual stress of the crimped fibers were less than those of the straight fiber with the same diameter. Moreover, crimped fibers with a large diameter and higher wave height would induce more recovery stress and residual stress. The maximum pullout resistance of the crimped fiber was a function of the wave depth, embedded length, yield strength, and flexural rigidity of the fiber.


2020 ◽  
Vol 2020 ◽  
pp. 1-18
Author(s):  
Jisong Zhang ◽  
Lihua Zhao ◽  
Guoqian Ren ◽  
Haijiang Li ◽  
Xiaofei Li

Sustainable building design has become a hot topic over the past decades. Many standards, databases, and tools have been developed for achieving a sustainable building. Not until recently have the importance of structural engineering and its contribution to sustainable building design been full recognised. However, due to the highly fragmented and diversity of knowledge across building and infrastructure domains, there is a lack of approach that can address all the sustainable issues within the structural design. This paper reviews the sustainable design from the perspective of structural engineering: (1) reviewing the current situation; (2) identifying the gaps and difficulties; and (3) making recommendations for future improvements. The strategies and indicators, as well as BIM-enabled methodology, for sustainable structural design (SSD) are also discussed in a holistic way. The results of this investigation show that most of the methods are not doing well in terms of delivering a successful sustainable structural design. It is expected that the future BIM could probably provide such a platform to address these issues.


2014 ◽  
Vol 900 ◽  
pp. 7-10
Author(s):  
Fabrizia Ghezzo ◽  
Xi Geng Miao ◽  
Chun Lin Ji ◽  
Ruo Peng Liu

The application of elastomeric coatings for improving the ability of already existing structures to dissipate the energy released by impact events has been investigated by many researchers in the past decade and is today an area of considerable interest. In recent years, polyurea has been successfully applied as a coating material for enhancing the impact protection of buildings and it has also demonstrated a considerable improvement of the survivability of metallic and non-metallic structures subjected to severe shock and impact loading conditions. Given its remarkable properties in terms of impact energy mitigation, life endurance and corrosion resistance, this material is currently of interest for its application in many fields of engineering. This paper presents and discusses the results of the mechanical characterization conducted on a polyurea elastomer fabricated following two different procedures and subjected to varying strain rates of compression load. The tests were conducted to verify the sensitivity of the material behavior to the varying loading conditions and to verify how the fabrication of the material in the laboratory can influence the test results.


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