Nonlinear adhesive behavior effects in a cracked orthotropic sheet stiffened by a semi-infinite orthotropic sheet
✍ Scribed by C.A. Bigelow
- Publisher
- Elsevier Science
- Year
- 1986
- Tongue
- English
- Weight
- 932 KB
- Volume
- 25
- Category
- Article
- ISSN
- 0013-7944
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✦ Synopsis
The stress-intensity factors are determined for a cracked orthotropic sheet adhesiveiy bonded to an orthotropic stringer where the adhesive layer is modeled with a nonlinear stress-strain curve. Since the stringer is modeled as a semi-infinite sheet, the solution is most appropriate for a crack tip located near a stringer edge. By the use of Green's functions and the complex variable theory of orthotropic elasticity developed by Lekhnitskii, a set of integral equations is obtained. The integral equations are replaced by an equivalent set of algebraic equations, which are solved to obtain the shear stress distribution in the adhesive layer. With these adhesive stresses, the cracktip stress-intensity factors are found.
When the adhesive was modeled with a nonlinear stress-strain curve, the peak shear stresses in the adhesive were considerably reduced in comparison to the solution for the linear elastic adhesive. This resulted in increases in the stress-intensity factors for the nonlinear adhesive solution compared to the linear adhesive solution. The nonlinear adhesive did not have a significant effect on the stress-intensity factor unless the near crack tip was beneath the stringer. The present investigation assumes that the adhesive bond remains intact. Onset of adhesive failure is predicted to occur at decreasing levels of applied stress as the crack propagates beneath the stringer. NOMENCLATURE half-crack length, m distance from edge of stringer to center of crack, m domain of integration stress functions, m3/N tangent shear modulus of adhesive layer, Pa thickness of layer j, m mode I component of stress-intensity factor, Pa,/; number of cells or collocation points in the domain complex kernels in integral equations (j, k = 1,2), I/(Pa m) Cartesian coordinates coordinates of concentrated load point, m complex variable (j = 1,2), m incremental distances (j = 1, N), m shear strains crack-face pressure, Pa shear stress, Pa adhesive shear stresses, Pa