Study of Welding Distortion and Residual Stress Considering Nonlinear Yield Stress Curves and Multi-constraint Equations

2016 ◽  
Vol 25 (10) ◽  
pp. 4484-4494 ◽  
Author(s):  
Youmin Rong ◽  
Guojun Zhang ◽  
Yu Huang
Keyword(s):  
Residual Stress ◽  
Yield Stress ◽  
Welding Distortion ◽  
Constraint Equations

scholarly journals Effect of Trailing Intensive Cooling on Residual Stress and Welding Distortion of Friction Stir Welded 2060 Al-Li Alloy

2018 ◽  
Vol 37 (5) ◽  
pp. 397-403 ◽  
Author(s):  
Shude Ji ◽  
Zhanpeng Yang ◽  
Quan Wen ◽  
Yumei Yue ◽  
Liguo Zhang
Keyword(s):  
Residual Stress ◽  
Friction Stir Welding ◽  
Plastic Strain ◽  
Welding Process ◽  
Butt Joint ◽  
Welding Distortion ◽  
Welding Temperature ◽  
Friction Stir ◽  
Numerical Simulation Methods ◽  
Conventional Cooling

AbstractTrailing intensive cooling with liquid nitrogen has successfully applied to friction stir welding of 2 mm thick 2060 Al-Li alloy. Welding temperature, plastic strain, residual stress and distortion of 2060 Al-Li alloy butt-joint are compared and discussed between conventional cooling and trailing intensive cooling using experimental and numerical simulation methods. The results reveal that trailing intensive cooling is beneficial to shrink high temperature area, reduce peak temperature and decrease plastic strain during friction stir welding process. In addition, the reduction degree of plastic strain outside weld is smaller than that inside weld. Welding distortion presents an anti-saddle shape. Compared with conventional cooling, the reductions of welding distortion and longitudinal residual stresses of welding joint under intense cooling reach 47.7 % and 23.8 %, respectively.

Measuring the Mechanical Properties of Thin Metal Films by Means of Bulge Testing of Micromachined Windows

1994 ◽  
Vol 356 ◽  
Author(s):  
V. M. Paviot ◽  
J. J. Vlassak ◽  
W. D. Nix
Keyword(s):  
Residual Stress ◽  
Silicon Nitride ◽  
Yield Stress ◽  
Plane Strain ◽  
Metal Films ◽  
Nitride Film ◽  
Silicon Nitride Film ◽  
Free Standing ◽  
Plastic Properties ◽  
Bulge Testing

AbstractFree-standing films of gold and aluminum have been fabricated using standard micro-machining techniques. LPCVD silicon nitride films are deposited onto (100) silicon wafers. Square and rectangular silicon nitride membranes are made by anisotropic etching of the silicon substrates. Then, metal films are deposited onto the silicon nitride membranes by means of evaporation. Finally, the sacrificial silicon nitride film is etched away by means of reactive plasma etching, resulting in well-defined, square and rectangular metal membranes.Bulge testing of square windows allows one to determine the biaxial modulus of the film as well as the residual stress in it. Testing rectangular windows yields the plane-strain elastic modulus and the residual stress. Since deformation in rectangular membranes approaches plane-strain deformation, this geometry is ideal for studying the plastic properties of the metal films. Stress-strain curves can be readily determined from the load-deflection curves of rectangular membranes. The gold films have a biaxial modulus of 161±3 GPa and a plane-strain modulus of 105±5 GPa, slightly lower than the literature values for a (111) textured film. The yield stress of these films is approximately 231±17 MPa at 10−4% plastic strain. The elastic moduli of the aluminum films are 105±3 GPa and 76.4±0.7 GPa, respectively; the yield stress of these films is 187±30MPa.

The Research of Surface Residual Stress about Glass Ceramics

2012 ◽  
Vol 226-228 ◽  
pp. 2014-2018
Author(s):  
Jing He Wang ◽  
Kui Wang ◽  
Xun Wang ◽  
Wei Song ◽  
Xiao Li Song ◽  
...  
Keyword(s):  
Residual Stress ◽  
Yield Stress ◽  
Glass Ceramics ◽  
Contact Theory ◽  
Spherical Indentation ◽  
Calculation Formula ◽  
Processing Quality ◽  
Surface Residual Stress ◽  
Stress Strain ◽  
Nano Indentation

We have researched the residual stress in super-smooth glass ceramics using nano-indentation technology, according to the characteristic that the residual stress in the process of pressure is sensitive to the pileup around the indenter, we can determine the changing area, then combine this with the elasto-plastic contact theory, thus the residual stress calculation formula is obtained. By the continuous strain obtained by a spherical indenter and the research on the yield stress and stress-strain curves of microcrystalline glass through spherical indentation experiments, we can get the rule which can tell us how the residual stress of the microcrystalline glass changes with the depth from surface. This research helps to improve the processing quality as well as the performance of the super-smooth surfaced microcrystalline glass, obviously it has a wide application prospect.

Hole-Drilling Method for Residual Stress Measurement - Consideration of Elastic-Plastic Material Properties

2013 ◽  
Vol 768-769 ◽  
pp. 174-181 ◽  
Author(s):  
David von Mirbach
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Yield Stress ◽  
Material Properties ◽  
Plastic Material ◽  
Hole Drilling ◽  
Hole Drilling Method ◽  
Drilling Method ◽  
Elastic Plastic Material ◽  
Ring Core

Two commonly used mechanical methods for the determination of residual stresses are the hole-drilling method and the ring-core method, which can be regarded as semi-destructive. The most restricting limitation for the general applicability of both methods, according to the current state of science and technology, is the fact that the scope for relatively low residual stress under 60% of the yield stress is limited.This is a result of the notch effect of the hole or ring core, which leads to a plastification around and on the bottom of the hole and ring shaped groove already at stresses well below the yield stress of the material. The elastic evaluation of the resulting plastic strains leads consequently to an overestimation of the delineated residual stresses. In this paper the influence of elastic-plastic material properties no the specific calibration function for the hole-drilling method using the differential method is studied, and the method of adaptive calibration functions is presented.

Computational Welding Mechanics and Concept of Inherent Strain for Industrial Applications

2007 ◽  
Vol 539-543 ◽  
pp. 181-186 ◽  
Author(s):  
Hidekazu Murakawa
Keyword(s):  
Residual Stress ◽  
Theoretical Prediction ◽  
Industrial Applications ◽  
Computational Method ◽  
Welding Distortion ◽  
Industrial Structures ◽  
Computational Welding Mechanics ◽  
Inherent Deformation ◽  
Inherent Strain

The distortion and the residual stress are the inevitable consequences of the welding and these may reduce the strength and the quality of the welded structures. To prevent the harmful influence of the welding distortion and the residual stress, their theoretical prediction is necessary. However the existing methods are mostly developed for the study of specimens in laboratories. Compared to the specimens, the structures manufactured in the industry are larger in size and more complex in geometry. For the theoretical prediction applicable to industrial structures, more powerful and practical methods are necessary. To achieve this goal, the authors developed a fast computational method for thermal elastic plastic analysis and an elastic finite element method using inherent deformation.

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