Shear strength criterion

An improved model based on a shear strength criterion... 

In the shear strength criterion, the debond crack propagates when the maximum IFSS at the debond crack tip z = L - tj reaches the shear bond strength, tb, i.e. 

Based on the shear strength criterion for the interface debonding, the condition for the fully bonded interface requires that the maximum IFSS be obtained at the... 

To show clearly how and to what extent the parameter, Zmax. varies with the properties of the interface and the composite constituents, a simple fiber pull-out model by Karbhari and Wilkins (1990) is chosen here. This model is developed based on the assumption of a constant friction shear stress, Tfr, in the context of the shear strength criterion for interface debonding. In this model, the partial debond stress may be written as... 

There are many features in the analysis of the fiber push-out test which are similar to fiber pull-out. Typically, the conditions for interfacial debonding are formulated based on the two distinct approaches, i.e., the shear strength criterion and the fracture mechanics approach. The fiber push-out test can be analyzed in exactly the same way as the fiber pull-out test using the shear lag model with some modifications. These include the change in the sign of the IFSS and the increase in the interfacial radial stress, (o,z), which is positive in fiber push-out due to expansion of the fiber. These modifications are required as a result of the change in the direction of the external stress from tension in fiber pull-out to compression in fiber push-out. 

Kim, J.K., Zhou, L.M. and Mai, Y.W. (1993b). Stress transfer in the fiber fragmentation test, part I. An improved analysis based on a shear strength criterion. J. Mater. Sci. 28, 6233-6245. 

Barton N.R., 1973, Review of a new shear strength criterion for rock joints[J]. Engineering Geology, 7(4) 287-332. 

Zhao X, 1997b, Joint surface matching and shear strength. Part B JMC-JRC shear strength criterion [J]. Int. J. Rock Mech. Min. Sci. Geomech. Abstr., 34(2) 179-185. 

Most comparisons of a failure criterion with failure data will be for the glass-epoxy data shown in Figure 2-36 as a function of off-axis angle 0 for both tension and compression loading [2-21]. The tension data are denoted by solid circles, and the compression data by solid squares. The tension data were obtained by use of dog-bone-shaped specimens, whereas the compression data were obtained by use of specimens with uniform rectangular cross sections. The shear strength for this glass-epoxy is 8 ksi (55 MPa) instead of the 6 ksi (41 MPa) in Table 2-3. 

As With the shear strength, the maximum shear strain is unaffected by the sign of the shear stress. The strains in principal material coordinates, 1- yi2 be found from the strains in body coordinates by transformation before the criterion can be applied. 

Equation 116 was also derived in Sect. 2. It shows that the fibre strength according to the shear failure criterion increases with improved alignment of the chains, and that it is proportional to the shear modulus g. 

The presented derivations of the load rate and the lifetime relationships applying the shear failure criterion are based on a single orientation angle for the characterisation of the orientation distribution. Therefore these relations give only an approximation of the lifetime of polymer fibres. Yet, they demonstrate quite accurately the effect of the intrinsic structural parameters on the time and the temperature dependence of the fibre strength. 

The maximum shearing stress criterion for failure simply states that failure (by yielding) would occur when the maximum shearing stress reaches a critical value (i.e., the material s yield strength in shear). Taking the maximum and minimum principal stresses to be and 03, respectively, then the failure criterion is given by Eqn. (2.3), where the yield strength in shear is taken to be one-half that for uniaxial tension. 

Hong Li, Xila Liu. 1993. Shear strength calculation based on concrete failure criterion. Engineering Mechanics 10(l) 52-60. 

During the process of stress wave propagation, tensile stresses or shear stresses do occur and cause rock material to fail in tension or in shear. Therefore, a modified principal stress failure criterion is applied to determining material status, which is suitable for describing material tensile failure or shear failure. The modified principal stress failure criterion dictates that when the major principal stress or the maximum shear stress in an element exceeds material tensile or shear strength, the element fails. After an element has failed, it will not be able to sustain any tensile and shear loadings, but it is still able to sustain compressive loading. The normal compressive stresses, and cr, of a failed ele-... 

The Hart Smith criterion proposes that the strength of laminates be characterised by generalizing the maximum-shear-stress criterion for ductile isotropic metals. 

The Tsai-Wu failure criterion requires prior knowledge of the lamina longitudinal tension and compression strengths, the transverse tension and compression strengths and the shear strength in the 1-2 (longitudinaltranverse) plane of the lamina. 

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