Some corrections and supplements to ?A generalised solution for the crack surface displacement of the mode I two-dimensional part-elliptical crack?

1993 ◽  
Vol 62 (3) ◽  
pp. R39-R48 ◽  
Author(s):  
G. S. Wang
Keyword(s):  
Crack Surface ◽  
Surface Displacement ◽  
Elliptical Crack ◽  
Mode I ◽  
Two Dimensional ◽  
Crack Surface Displacement

The First-Order Variation of the Displacement Field Due to Geometrical Changes in an Elliptical Crack

1990 ◽  
Vol 57 (3) ◽  
pp. 639-646 ◽  
Author(s):  
T. Nishioka ◽  
S. N. Atluri
Keyword(s):  
Stress Intensity ◽  
Displacement Field ◽  
Crack Surface ◽  
Surface Displacement ◽  
Intensity Variation ◽  
Elastic Solid ◽  
Elliptical Crack ◽  
Weight Functions ◽  
Surface Flaws ◽  
Analytical Expressions

Analytical expressions are derived for the derivatives of the crack-surface displacement field, with respect to the lengths of the major and minor axes, respectively, of an elliptical crack embedded in an infinite isotropic elastic solid, when the crack faces are subjected to arbitrary tractions. These results are shown to lead, in turn, to analytical expressions for weight functions for the stress intensity factors along the fronts of elliptical-shaped embedded or part-elliptical shaped surface flaws, when a simple two-parameter characterization of the stress intensity variation along the flaw border is used. In the case of part-elliptical surface flaws, a finite-element alternating method, based on the Schwartz-Neumann superposition technique, is proposed to determine the coefficients in the analytical expressions for crack-surface displacements, and their gradients with respect to the crack dimensions.

A New Modified Crack Surface Displacement Extrapolation Method for Analysis of Package Delamination

2005 ◽  
Author(s):  
Guojun Hu ◽  
Andrew A. O. Tay
Keyword(s):  
Vapor Pressure ◽  
Crack Surface ◽  
Surface Displacement ◽  
Extrapolation Method ◽  
New Method ◽  
Bimaterial Interface ◽  
Solder Reflow ◽  
Displacement Extrapolation Method ◽  
Crack Surface Displacement ◽  
Displacement Extrapolation

Based on a new second-order analysis of the bimaterial interface crack, a modified crack surface displacement extrapolation method (MCSDEM) for evaluating the stress intensity factor (SIF) and mode mixity at a crack has been developed. Unlike existing methods which require extrapolation of values of SIFs with the concomitant uncertainties, the new method engenders a constant SIF over a considerable distance from the crack tip. The new method is also much less sensitive to mesh density than existing methods. The new MCSDEM is then used to investigate the effects of temperature, moisture diffusion and interface vapor pressure on the delamination of the interface between the leadframe pad and the encapsulant of a plastic quad flat pack (PQFP) during solder reflow for both eutectic solder and leadfree solder. Using a 160-leaded PQFP as a test vehicle, the effect of initial delamination size varying from 0.1 mm to 3.5 mm was studied. The results show that the relative contributions of temperature, moisture and interface vapor pressure is qualitatively different for solder reflow of leadfree soldered and eutectic soldered components.

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