scholarly journals Active Reinforcing Fiber of Cementitious Materials Using Crimped NiTi SMA Fiber for Crack-Bridging and Pullout Resistance

Materials ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 3845
Author(s):  
Eunsoo Choi ◽  
Ha Vinh Ho ◽  
Jong-Su Jeon
Keyword(s):  
Residual Stress ◽  
Flexural Rigidity ◽  
Large Diameter ◽  
Cold Drawing ◽  
Cementitious Materials ◽  
Tensile Behavior ◽  
Recovery Stress ◽  
Pullout Resistance ◽  
Niti Sma ◽  
Straight Fiber

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.

Estimation of Residual Stress in Spiral Welded Pipe: Regression and Numerical Model

2012 ◽  
Author(s):  
Abul Fazal M. Arif ◽  
Ahmad S. Al-Omari ◽  
Anwar K. Sheikh ◽  
Yagoub Al-Nassar ◽  
M. Anis
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Critical Role ◽  
Large Diameter ◽  
Element Model ◽  
Regression Equation ◽  
Field Analysis ◽  
Welding Parameters ◽  
Splitting Test ◽  
Welded Pipe

Double submerged spiral-welded pipe (SWP) is used extensively throughout the world for large-diameter pipelines. Fabrication-induced residual stresses in spiral welded pipe have received increasing attention in gas, oil and petrochemical industry. Several studies reported in the literature verify the critical role of residual stresses in the failure of these pipes. Therefore, it is important that such stresses are accounted for in safety assessment procedures such as the British R6 and BS7910. This can be done only when detailed information on the residual stress distribution in the component is known. In industry, residual stresses in spiral welded pipe are measured experimentally by means of destructive techniques known as Ring Splitting Test. In this study, statistical analysis and linear-regression modeling were used to study the effect of several structural, material and welding parameters on ring splitting test opening for spiral welded pipes. The experimental results were employed to develop an appropriate regression equation, and to predict the residual stress on the spiral welded pipes. It was found that the developed regression equation explains 36.48% of the variability in the ring opening. In the second part, a 3-D finite element model is presented to perform coupled-field analysis of the welding of spiral pipe. Using this model, temperature as well as stress fields in the region of the weld edges is predicted.

Minimization of the Local Residual Stress in 3D Flip Chip Structures by Optimizing the Mechanical Properties of Electroplated Materials and the Alignment Structure of TSVs and Fine Bumps

2011 ◽  
Author(s):  
Kohta Nakahira ◽  
Hironori Tago ◽  
Fumiaki Endo ◽  
Ken Suzuki ◽  
Hideo Miura
Keyword(s):  
Mechanical Properties ◽  
Residual Stress ◽  
Thermal Deformation ◽  
Flip Chip ◽  
Flexural Rigidity ◽  
Three Dimensional ◽  
Strain Gauges ◽  
Copper Interconnection ◽  
Induced Stress ◽  
Alignment Structure

Since the thickness of the stacked silicon chips in 3D integration has been thinned to less than 100 μm, the local thermal deformation of the chips has increased drastically because of the decrease of the flexural rigidity of the thinned chips. The clear periodic thermal deformation and thus, the thermal residual stress distribution appears in the stacked chips due to the periodic alignment of metallic bumps, and they deteriorate the reliability of products. In this paper, the dominant structural factors of the local residual stress in a silicon chip are discussed quantitatively based on the results of a three-dimensional finite element analysis and the measurement of the local residual stress in a chip using stress sensor chips. The piezoresistive strain gauges were embedded in the sensor chips. The length of each gauge was 2 μm, and an unit cell consisted of 4 gauges with different crystallographic directions. This alignment of strain gauges enables to measure the tensor component of three-dimensional stress fields separately. Test flip chip substrates were made by silicon chip on which the area-arrayed tin/copper bumps were electroplated. The width of a bump was fixed at 200 μm, and the bump pitch was varied from 400 μm to 1000 μm. The thickness of the copper layer was about 40 μm and that of tin layer was about 10 μm. This tin layer was used for the rigid joint formation by alloying with copper interconnection formed on a stress sensing chip. The measured amplitude of the residual stress increased from about 30 MPa to 250 MPa depending on the combination of materials such as bump, underfill, and interconnections. It was confirmed that both the material constant of underfill and the alignment structure of fine bumps are the dominant factors of the local deformation and stress of a silicon chip mounted on area-arrayed metallic bumps. It was also confirmed experimentally that both the hound’s-tooth alignment between a TSV (Through Silicon Via) and a bump and control of mechanical properties of electroplated copper thin films used for the TSV and bump is indispensable in order to minimize the packaging-induced stress in the three-dimensionally mounted chips. This test chip is very effective for evaluating the packaging-process induced stress in 3D stacked chips quantitatively.

Weld Residual Stress in Large Diameter Nuclear Nozzles

2011 ◽  
Author(s):  
Tao Zhang ◽  
F. W. Brust ◽  
Gery Wilkowski
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Nuclear Power ◽  
Kinematic Hardening ◽  
Large Diameter ◽  
Thick Wall ◽  
Isotropic Hardening ◽  
Residual Stress Field ◽  
Mixed Hardening ◽  
Weld Residual Stress

Weld residual stresses in nuclear power plant can lead to cracking concerns caused by stress corrosion. These are large diameter thick wall pipe and nozzles. Many factors can lead to the development of the weld residual stresses and the distributions of the stress through the wall thickness can vary markedly. Hence, understanding the residual stress distribution is important to evaluate the reliability of pipe and nozzle joints with welds. This paper represents an examination of the weld residual stress distributions which occur in various different size nozzles. The detailed weld residual stress predictions for these nozzles are summarized. Many such weld residual stress solutions have been developed by the authors in the last five years. These distributions will be categorized and organized in this paper and general trends for the causes of the distributions will be established. The residual stress field can therefore feed into a crack growth analysis. The solutions are made using several different constitutive models such as kinematic hardening, isotropic hardening, and mixed hardening model. Necessary fabrication procedures such as repair, overlay and post weld heat treatment are also considered. Some general discussions and comments will conclude the paper.

Tensile Behavior of Large Diameter Carbon Fiber Anchors

2021 ◽  
pp. 1199-1207
Author(s):  
Emrah Tasdemir ◽  
Rudolf Seracino ◽  
Mervyn Kowalsky ◽  
James Nau
Keyword(s):  
Carbon Fiber ◽  
Large Diameter ◽  
Tensile Behavior

Inducing recovery stress of NiTiNb SMA wires using heat of hydration for confining concrete

2011 ◽  
Vol 22 (17) ◽  
pp. 1949-1957 ◽  
Author(s):  
Eunsoo Choi ◽  
Baik-Soon Cho ◽  
Joonam Park ◽  
Kyoungsoo Park
Keyword(s):  
Residual Stress ◽  
Shape Memory ◽  
Concrete Beams ◽  
Plain Concrete ◽  
Heat Of Hydration ◽  
Reinforced Concrete Beams ◽  
Recovery Stress ◽  
Concrete Cylinders ◽  
Temperature Window ◽  
Compressive Tests

This study suggests the utilization of heat of hydration of concrete to activate the shape memory effect (SME) of shape memory alloy (SMA) wires embedded in concrete and produce recovery and residual stress on the wires. This method is more convenient than the previous electronic resistance heating. For the purpose, this study prepares NiTiNb SMA wires that show appropriate temperature window for the use of heat of hydration. Axial compressive tests of concrete cylinders confined by the NiTiNb SMA wire jackets are used to prove that the utilization of heat of hydration is valid to generate recovery and residual stress in the SMA wires. The confined cylinders show increased peak strengths and much larger failure strains than those of the plain concrete. The general behavior of the SMA wire-confined specimens in this study is similar to that of specimens heated by electronic heating jacket. Also, this study explains two examples for the utilization of heat of hydration for the SME in reinforced concrete beams and columns.

Influence of Processing State on Recovery Stress in NiTiNb Shape Memory Alloy

2014 ◽  
Vol 875-877 ◽  
pp. 1525-1528 ◽  
Author(s):  
Er Min Wang ◽  
Qi Hu Hong ◽  
Zhi Ming Ni ◽  
Jin Han
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Stress Level ◽  
Microstructure Evolution ◽  
Hot Rolling ◽  
Cold Drawing ◽  
Eutectic Microstructure ◽  
Recovery Stress ◽  
Tini Phase

Self-made tension machine was used to measure the evolution of recovery stress under different processing state for NiTiNb alloy. Then, SEM was used to investigate the microstructure evolution. The results show that the range of the highest recovery stress for forged NiTiNb alloy is between 210-215MPa. Otherwise, the recovery stress level of the samples enduring cold drawing and hot rolling is basically same, which all belong to the rage of 210-220MPa. After forging, the firstly precipitated TiNi phase particles become fine, only 5-8μm. The Nb tablets in eutectic microstructure, which originally contributed between TiNi phase particles, appear spheroidization.

Preliminary Results of Stress Recovery of Constrained NiTi SMA Wire for Aerospace Applications

2010 ◽  
Vol 643 ◽  
pp. 15-18
Author(s):  
Júlio Cesar Santos ◽  
Antunes Andre Da Silva ◽  
Afonso Paulo Monteiro Pinheiro ◽  
Leonardo Kyo Kabayama ◽  
Odair Doná Rigo ◽  
...  
Keyword(s):  
Shape Recovery ◽  
Electrical Current ◽  
Recovery Stress ◽  
Wire Electrode ◽  
Recovery Effect ◽  
Ignition System ◽  
Gas Leakage ◽  
Aerospace Applications ◽  
Niti Sma ◽  
The Wire

The rocket propellant ignition system uses electro-explosive device actuated by wire electrode. Those wires are usually made by Fe-Ni based alloy with controlled thermal expansion inserted into a ceramic feed-through and are connected to thin resistive wire which is heated through the passage of an electrical current for propellant ignition. The contact between ceramic feed-through and wires should be reliable since sometimes it could fail. A novel alternative process is to use SMA wires taking into account the shape recovery effect constraining the wire inside the feed-through. The recovery stress of 326 MPa for 4% pre-strain should be enough to constrain the wire inside the feed-trough avoiding the gas leakage.

An Experimental Study on Improved Production Process of Large-Diameter Cylinder Assembly

2013 ◽  
Vol 427-429 ◽  
pp. 200-203
Author(s):  
Hui Fan Zeng
Keyword(s):  
Residual Stress ◽  
Large Diameter ◽  
Aging Treatment ◽  
Dimensional Accuracy ◽  
Welding Residual Stress ◽  
Production Cycle ◽  
Welding Deformation ◽  
Residual Stress State ◽  
Deformation Law ◽  
Large Cylinder

Post-welding annealing and aging treatment are commonly used to reduce welding residual stress and post-welding deformation. However, both show their limited effect in the application of large workpieces. Present study attempts to explore the residual stress state and post-welding deformation law of large workpieces by improving the production technology of the important workpieces of certain engineering equipment a large cylinder assembly. It is proposed that the deformation induced by post-welding residual stress can be effectively compensated by increasing the dimensional accuracy in cutting processing. In this way, aging process is replaced and qualified products can be obtained in a much shorter production cycle.

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