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Geometric factor for mode II stress intensity factor for a finite strip under under pure shear loading
Thu, 2009-08-20 23:30 - aysha.kalanad
The geometric factor for mode I stress intensity factor for a finite strip under pure tensile loading is reported in Tada handbook as F(a/h) = 1.122 - 0.231(a/h) + 10.55*(a/h)^2 - 21.71*(a/h)^3 + 30.382*(a/h)^4 , but in the existing literature, I could not find such geometric factor for mode II stress intensity factor for a finite strip under under pure shear loading. Does anyone know such geometric factor for mode II stress intensity factor for a finite strip under under pure shear loading, if it is reported in the existing literature? or, if it is available in any unpublished sources?
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Mode II stress intensity factor
Aysha,
You should refer to Prof. Suresh's paper titled 'Mixed-mode fracture toughness of ceramic materials' (1990) from Journal of American Ceramic Society. In this paper, the authors use a 4-point bend specimen to develop an experimental technique where the combined effect of Mode I and Mode II is studied. They give expressions for both KI and KII as follows.
KI=6*P*(A-B)/(A+B)/(B*W)*sqrt(∏a)*S/W*FI(a/W)
KII=P*(A-B)/(A+B)/(B*W)*sqrt(∏a)*FII(a/W)
Here, P is the applied load, A and B are the offset of the load points from the center (for the assymetric 4-point bend specimen), B is the thickness and W is the width of the specimen. S is the off-set of the initial crack from the center line. FI and FII are geometric factors which depend on a/W (or on a/h in your case).
From this formula, if you choose S to be 0 (ie initial crack at the mid-span), you find that KI goes to 0 and KII is non-zero, implying pure Mode-II conditions.The geometric factors have been reported by Prof. Suresh and his co-authors in this paper and are plotted against the relative crack depth (a/W).
Arun