Accession Number : ADA305152

Title :   A Cracked Orthotropic Sheet Stiffened by a Semi-Infinite Orthotropic Sheet.

Descriptive Note : Technical paper,

Corporate Author : NATIONAL AERONAUTICS AND SPACE ADMINISTRATION HAMPTON VA LANGLEY RESEARCH CEN TER

Personal Author(s) : Bigelow, C. A.

PDF Url : ADA305152

Report Date : JUL 1985

Pagination or Media Count : 26

Abstract : The stress-intensity factor is determined for a cracked orthotropic sheet adhesively bonded to an orthotropic stringer. Since the stringer is modeled as a semi-infinite sheet, the solution is most appropriate for a crack tip located near a stringer edge. Both adherends are treated as homogeneous, orthotropic media. It is assumed they are in plane stress and the adhesive is in pure shear. From 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 is solved to obtain the shear-stress distribution in the adhesive layer. With these stresses, equations for the stress-intensity factors at both crack tips are found. A parametric study is conducted to determine the sensitivity of the system to material properties and specimen configuration. Unless the crack tip is very close to or under the stringer, the stress-intensity factor is approximately that of an unstiffened sheet. However, as the crack propagates beneath the stringer, the stress-intensity factor decreases significantly. Increasing the stiffness of the stringer or the adhesive also results in a decrease in the stress-intensity factor. (MM)

Descriptors :   *CRACKING(FRACTURING), *STIFFENING, *EPOXY LAMINATES, STIFFNESS, CRACKS, DAMAGE ASSESSMENT, DISPLACEMENT, FIBER REINFORCED COMPOSITES, ADHESION, ELASTIC PROPERTIES, MODULUS OF ELASTICITY, SHEAR STRESSES, AEROSPACE CRAFT, TOLERANCES(MECHANICS), GREENS FUNCTIONS, INTEGRAL EQUATIONS, FLEXIBLE STRUCTURES, POISSON RATIO, ADHESIVE BONDING, GRAPHITE EPOXY COMPOSITES, STRESS CONCENTRATION.

Subject Categories : Laminates and Composite Materials
      Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE