Transient Thermal Load Effects on Coatings Bonded to Cylindrical Substrates and Containing Circumferential Cracks

1988 ◽  
Vol 110 (1) ◽  
pp. 35-40 ◽  
Author(s):  
K. Kokini ◽  
T. R. Hornack
Keyword(s):  
Stress Intensity ◽  
Stress Intensity Factors ◽  
Thermal Load ◽  
Edge Crack ◽  
Ceramic Coatings ◽  
The Finite Element Method ◽  
Intensity Factors ◽  
Transfer Rates ◽  
Load Effects ◽  
Transient Thermal

The effect of a transient thermal load on a coating which is bonded to a cylindrical substrate is analyzed using fracture mechanics by considering the presence of a circumferential edge crack normal to the inner boundary of the coating. The solution is obtained using the finite element method and is compared to the exact solution of the problem. The analysis is then used to show that smaller heat transfer rates at the boundary result in smaller stress intensity factors. For three different materials combinations, including two ceramic coatings on metal, the nondimensional stress intensity factor has a similar magnitude for short crack lengths, but varies appreciably as the crack length becomes longer. It is also determined that inner coatings result in smaller or comparable stress intensity factors than thicker ones.

Experimental Determination of KI for Short Internal Cracks

2001 ◽  
Vol 68 (6) ◽  
pp. 937-943 ◽  
Author(s):  
K. Bearden ◽  
J. W. Dally ◽  
R. J. Sanford
Keyword(s):  
Stress Intensity ◽  
Stress Intensity Factors ◽  
Edge Crack ◽  
Series Solution ◽  
Experimental Studies ◽  
Experimental Methods ◽  
Internal Crack ◽  
Intensity Factors ◽  
Mode Stress

Since the pioneering discussion by Irwin, a significant effort has been devoted to determining stress intensity factors (K) using experimental methods. Techniques have been developed to determine stress intensity factors from photoelastic, strain gage, caustics, and moire´ data. All of these methods apply to a relatively long single-ended-edge crack. To date, the determination of K for internal cracks that are double-ended by experimental methods has not been addressed. This paper describes a photoelastic study of tension panels with both central and eccentric internal cracks. The data recorded in the experiments was analyzed using a new series solution for the opening-mode stress intensity factor for an internal crack. The data was also analyzed using the edge-crack series solution, which is currently employed in experimental studies. Results indicated that the experimental methods usually provided results accurate to within three to five percent if the series solution for the internal crack was employed in an overdeterministic numerical analysis of the data. Comparison of experimental results using the new series for the internal crack and the series for an edge crack showed the superiority of the new series.

Stress Intensity Factor Analyses of Interface Cracks Between Anisotropic Media in Electronic Packages

2003 ◽  
Author(s):  
Toru Ikeda ◽  
Koh Yamanaga ◽  
Noriyuki Miyazaki
Keyword(s):  
Finite Element Method ◽  
Stress Intensity ◽  
Interface Crack ◽  
Stress Intensity Factors ◽  
Anisotropic Materials ◽  
Electronic Packages ◽  
Strain Condition ◽  
The Finite Element Method ◽  
Intensity Factors ◽  
Generalized Plane Strain

Delamination from interfaces between dissimilar materials is the primary cause of failure in electronic packages. Fracture mechanics is a powerful tool for the evaluation of delamination. However, many materials used in electronic packages such as composite materials and single crystals are anisotropic materials. Stress intensity factors of an interface crack between dissimilar anisotropic materials which proposed by Hwu are useful for evaluating the reliability of plastic packages. However, numerical methods that can analyze the stress intensity factors of an interface have not been developed. We propose herein a new numerical method for the analysis of an interface crack between dissimilar anisotropic materials. The stress intensity factors of an interface crack are based on the generalized plane strain condition. The energy release rate is obtained by the virtual crack extension method in conjunction with the finite element method for the generalized plane strain condition. The energy release rate is separated into individual modes of stress intensity factors, KI, KII, and KIII, using the principal of superposition. The target problem to be solved is superposed on the asymptotic solution of displacement in the vicinity of an interface crack tip, which is described using the Stroh formalism. Analyses of the stress intensity factors of center interface cracks between semi-infinite dissimilar anisotropic media subjected to concentrated self-balanced loads on the center of crack surfaces as well as to uniform loads are demonstrated. The present method accurately provides the mode-separated stress intensity factors using relatively course meshes for the finite element method.

Determination of energy release rates and stress-intensity factors by the finite-element method

1972 ◽  
Vol 7 (2) ◽  
pp. 125-131 ◽  
Author(s):  
J R Dixon ◽  
J S Strannigan
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Stress Intensity ◽  
Energy Release ◽  
Stress Intensity Factors ◽  
The Finite Element Method ◽  
Intensity Factors ◽  
Release Rates ◽  
Energy Release Rates ◽  
Element Method

It is shown that the finite-element method of analysis, used in conjunction with a generalized form of the compliance equations of fracture mechanics, can provide a general means of determining energy release rates and stress-intensity factors for complex crack configuration and loadings. The method is applied to several crack configurations in flat plates and in round bars.

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