3D Nonlinear Stress Analysis of Tin Whisker Initiation on Lead-Free Components

2003 ◽  
Vol 125 (4) ◽  
pp. 621-624 ◽  
Author(s):  
John H. Lau ◽  
Stephen H. Pan
Keyword(s):  
Stress Analysis ◽  
Compressive Stress ◽  
Chemical Reaction ◽  
Plastic Material ◽  
Copper Substrate ◽  
Three Dimensional ◽  
Lead Free ◽  
Tin Whisker ◽  
Weak Spot ◽  
Nonlinear Stress

In this study, a three-dimensional (3D) nonlinear stress analysis of the tin whisker initiation on a pure matte Sn-plated copper substrate is investigated. The structure is subjected to a compressive stress acting at the Sn layer which is generated by the spontaneous chemical reaction of the Sn layer and the Sn5Cu6 layer. The Sn layer is assumed to be an elasto-plastic material. The results presented herein is useful in understanding why the compressive stress in the Sn layer can initiate a tin whisker near the weak spot of a SnOx layer.

Steady Flow and Wall Compression in Stenotic Arteries: A Three-Dimensional Thick-Wall Model With Fluid–Wall Interactions

2001 ◽  
Vol 123 (6) ◽  
pp. 548-557 ◽  
Author(s):  
Dalin Tang ◽  
Chun Yang ◽  
Shunichi Kobayashi ◽  
David N. Ku
Keyword(s):  
Compressive Stress ◽  
Stokes Equations ◽  
Tube Wall ◽  
Three Dimensional ◽  
Thick Wall ◽  
Critical Flow ◽  
Severe Stenosis ◽  
Wall Model ◽  
Nonlinear Stress ◽  
Wall Interactions

Severe stenosis may cause critical flow and wall mechanical conditions related to artery fatigue, artery compression, and plaque rupture, which leads directly to heart attack and stroke. The exact mechanism involved is not well understood. In this paper, a nonlinear three-dimensional thick-wall model with fluid–wall interactions is introduced to simulate blood flow in carotid arteries with stenosis and to quantify physiological conditions under which wall compression or even collapse may occur. The mechanical properties of the tube wall were selected to match a thick-wall stenosis model made of PVA hydrogel. The experimentally measured nonlinear stress–strain relationship is implemented in the computational model using an incremental linear elasticity approach. The Navier–Stokes equations are used for the fluid model. An incremental boundary iteration method is used to handle the fluid–wall interactions. Our results indicate that severe stenosis causes considerable compressive stress in the tube wall and critical flow conditions such as negative pressure, high shear stress, and flow separation which may be related to artery compression, plaque cap rupture, platelet activation, and thrombus formation. The stress distribution has a very localized pattern and both maximum tensile stress (five times higher than normal average stress) and maximum compressive stress occur inside the stenotic section. Wall deformation, flow rates, and true severities of the stenosis under different pressure conditions are calculated and compared with experimental measurements and reasonable agreement is found.

scholarly journals Origin and Application of the Twinned Calcite Strain Gauge

Geosciences ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 296
Author(s):  
Richard H. Groshong
Keyword(s):  
Stress Analysis ◽  
Strain Gauge ◽  
Strain Tensor ◽  
Three Dimensional ◽  
Constant Strain Rate ◽  
Axis Orientation ◽  
Order Of Magnitude ◽  
Rate Experiment ◽  
Strain Axis ◽  
Expected Values

This paper is a personal account of the origin and development of the twinned-calcite strain gauge, its experimental verification, and its relationship to stress analysis. The method allows the calculation of the three-dimensional deviatoric strain tensor based on five or more twin sets. A minimum of about 25 twin sets should provide a reasonably accurate result for the magnitude and orientation of the strain tensor. The opposite-signed strain axis orientation is the most accurately located. Where one strain axis is appreciably different from the other two, that axis is generally within about 10° of the correct value. Experiments confirm a magnitude accuracy of 1% strain over the range of 1–12% axial shortening and that samples with more than 40% negative expected values imply multiple or rotational deformations. If two deformations are at a high angle to one another, the strain calculated from the positive and negative expected values separately provides a good estimate of both deformations. Most stress analysis techniques do not provide useful magnitudes, although most provide a good estimate of the principal strain axis directions. Stress analysis based on the number of twin sets per grain provides a better than order-of-magnitude approximation to the differential stress magnitude in a constant strain rate experiment.

Finite Element Analysis of Drum on the New Type Self-Driven Towing Machine for Cable

2011 ◽  
Vol 55-57 ◽  
pp. 664-669
Author(s):  
Jin Ning Nie ◽  
Hui Wang ◽  
De Feng Xie
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Stress Analysis ◽  
Compressive Stress ◽  
Wire Rope ◽  
Ansys Software ◽  
Element Analysis ◽  
Structure Improvement ◽  
Improvement Measures ◽  
New Type

According to the situation that the dual-friction drums on the new type towing machine lack stress analysis when designed, the safety is difficult to test and verify. The pull of wire rope in various positions was derived and calculated, so both compressive stress and tangent friction force generated by the pull of wire rope were calculated. The result made by ANSYS software demonstrates the safety of the left drum which suffers from larger loads, structure improvement measures are put forward for the drum.

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