Moisture-Assisted Crack Growth in Polymer Adhesive-Glass Sandwich Geometries

1994 ◽  
Vol 338 ◽  
Author(s):  
J. E. Ritter ◽  
T. J. Lardner ◽  
G. C. Prakash ◽  
A. J. Stewart

ABSTRACTMoisture-assisted crack growth in polymer/glass interfaces was measured as a function of the applied energy release using a four-point flexure test coupled with an inverted microscope. The specimens consisted of two glass plates bonded together with a thin layer of epoxy adhesive. Roughening the surface of one of the interfaces increased its fracture resistance sufficiently so that crack growth on this interface was inhibited. Thus, crack growth would occur only on the “smooth” interface (one with the least fracture resistance) or in the case where both interfaces were smooth, dual cracking occurred. Finite element analysis was used to explain the observed crack growth results.

Author(s):  
Vinícius Felipe Wandscher ◽  
César Dalmolin Bergoli ◽  
Ariele Freitas de Oliveira ◽  
Osvaldo Bazzan Kaizer ◽  
Alexandre Luiz Souto Borges ◽  
...  

Author(s):  
Charles Fourcade ◽  
Minji Fong ◽  
James Axline ◽  
Do Jun Shim ◽  
Chris Lohse ◽  
...  

Abstract As part of a fatigue management program for subsequent license renewal, a flaw tolerance evaluation based on ASME Code, Section XI, Appendix L may be performed. The current ASME Code, Section XI, Appendix L flaw tolerance methodology requires determination of the flaw aspect ratio for initial flaw size calculation. The flaw aspect ratios listed in ASME Section XI, Appendix L, Table L-3210-2, for austenitic piping for example, are listed as a function of the membrane-to-gradient cyclic stress ratio. The Code does not explicitly describe how to determine the ratio, especially when utilizing complex finite element analyses (FEA), involving different loading conditions (i.e. thermal transients, piping loads, pressure, etc.). The intent of the paper is to describe the methods being employed to determine the membrane-to-gradient cyclic stress ratios, and the corresponding flaw aspect ratios (a/l) listed in Table L-3210-2, when using finite element analysis methodology. Included will be a sample Appendix L evaluation, using finite element analysis of a pressurized water reactor (PWR) pressurizer surge line, including crack growth calculations for circumferential flaws in stainless steel piping. Based on this example, it has been demonstrated that, unless correctly separated, the membrane-to-gradient cyclic stress ratios can result in extremely long initial flaw lengths, and correspondingly short crack growth durations.


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