Abstract
A mechanical and optical characterization study in a uniaxial field was conducted on a commercial di-phase photoelastic material suitable for stress freezing. Results were used in a plane-strain theory for predicting nonlinear crack-tip behavior with the Prandtl-Reuss equations and a Mises criterion. These predictions were compared with frozen-stress photoelastic results obtained from experiments on a variety of technologically important three-dimensional cracked-body problems. Results indicate substantially greater stiffness or constraint in the nonlinear zone near the crack tip than predicted using uniaxial data. However, the value of the maximum shear stress at the onset of nonlinear behavior was accurately established and was the same for all cases examined.
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Abbreviations
- n, t, z :
-
local rectangular Cartesian coordinates along the flaw border
- σ ij i,j=n,z :
-
stress components in plane normal to the flaw surface and flaw border near crack tip (kPa)
- σ ij o i,j=n,z :
-
part of regular stress field near crack tip (kPa)
- r, θ:
-
polar coordinates, measured from crack tip (mm, rad)
- K I :
-
Mode I — stress-intensity factor (kPa-m1/2)
- K II :
-
Mode II — stress-intensity factor (kPa-m1/2)
- K AP :
-
Mode I — apparent stress-intensity factor [τ max (8\(\pi r)^{1/2} \)] (kPa-m1/2)
- a :
-
characteristic crack depth (mm)
- τ max :
-
maximum shear stress inn−z plane (kPa)
- N′:
-
stress-fringe order
- f :
-
material-fringe value (N/m)
- t′:
-
slice thicknes in thet direction (mm)
- q :
-
remote loading parameter (i.e. uniform stress, pressure, etc.) (kPa)
- E :
-
Young's modulus (kPa)
- σº :
-
proportional-limit stress (kPa)
- α:
-
material constant
- N :
-
hardening exponent
- δe :
-
effective stress (kPa)
- ∈1 :
-
total strain (mm/mm)
- γe :
-
maximum shear strain (rad)
- G :
-
shear modulus (kPa/rad)
- σ rs rs,=1,2,3:
-
stress components (kPa)
- ∈ rs rs,=1,2,3:
-
strain components (mm/mm)
- σ e :
-
effective stress (kPa)
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J. J. McGowan was Assistant Professor in same department at VPI & SU
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Smith, C.W., McGowan, J.J. & Peters, W.H. A study of crack-tip nonlinearities in frozen-stress fields. Experimental Mechanics 18, 309–315 (1978). https://doi.org/10.1007/BF02324162
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DOI: https://doi.org/10.1007/BF02324162