Mode II weight functions for isotropic and orthotropic double cantilever beams |
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Authors: | L Brandinelli R Massabò |
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Affiliation: | (1) Department of Structural and Geotechnical Engineering, University of Genova, Via Montallegro 1, Genova, 16145, Italy |
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Abstract: | Approximate weight functions are derived and validated numerically for isotropic and orthotropic double cantilever beams loaded
in mode II. They define the stress intensity factor at the crack tip due to a pair of unit point forces acting tangentially
to the crack surfaces and have been deduced using asymptotic matching through finite elements and an orthotropy rescaling
technique. Along with the related mode I weight functions, which are recalled in the paper, the functions can be used to formulate
mixed mode problems in beams and plates as integral equations so avoiding the limitations imposed on accuracy by approximations
based on structural theories. An accurate method such as the weight function method becomes necessary when dealing with short
cracks, crack initiation and large scale bridging delamination problems with crack wake mechanisms acting over several scales.
The accuracy of modes I and II solutions based on beam theory approximations is shown to be strongly influenced by the length
of Dugdale type cohesive regions, with short lengths giving rise to large errors in the fracture parameters. Stress intensity
factors obtained using the proposed functions for special problems agree with solutions from the literature. |
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Keywords: | Bridging and cohesive mechanisms double cantilever beam end notched flexural specimen mixed-mode bending specimen orthotropy rescaling weight functions |
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