Oblique surface cracking and crack closure in an orthotropic medium under contact loading

This article presents analytical methods for analysis of an inclined surface crack in an orthotropic medium subjected to contact loading. Governing partial differential equations are derived in accordance with plane theory of orthotropic elasticity. Contact and crack problems are formulated separately utilizing Fourier transformation techniques. The contact problem consists of a rigid flat punch pressing upon an orthotropic half-plane, and is reduced to a singular integral equation of the second kind. The surface crack is assumed to be tilted at an arbitrary angle with respect to the normal of the half-plane surface. Three different crack configurations are considered, which are completely closed, partially-closed, and fully-open cracks. Frictional contact between the crack faces is implemented in the cases of completely closed, and partially-closed cracks. A single singular integral equation is derived for the completely closed crack, whereas each of the problems of partially- and fully-open cracks requires derivation of a set of two singular integral equations. The contact problem and each of the crack problems are solved numerically by means of the expansion-collocation technique. A flowchart is developed and implemented to detect the type of crack closure configuration under a given contact loading. The parametric analyses carried out illustrate the influences of factors such as crack inclination angle, crack face and contact surface friction coefficients, material orthotropy, and relative punch location on crack face contact stresses, degree of crack closure, and mode I and II stress intensity factors.


Computation of Thermal Fracture Parameters for Inclined Cracks in Functionally Graded Materials Using Jk-Integral
Dağ, Serkan (Informa UK Limited, 2009-01-01)
This article describes the formulation and implementation of the Jk-integral for the analysis of inclined cracks located in functionally graded materials (FGMs) that are subjected to thermal stresses. The generalized definition of the Jk-integral over a vanishingly small curve at the tip of an inclined crack is converted to a domain independent form that consists of area and line integrals defined over finite domains. A numerical procedure based on the finite element method is then developed, which allows t...
Surfactant-modified multiscale composites for improved tensile fatigue and impact damage sensing
Yesil, Sertan; Winkelrnann, Charles; Bayram, Göknur; La Saponara, Valeria (Elsevier BV, 2010-10-25)
This paper documents the mechanical and electrical performance of self-sensing conductive polymer composites prepared with a low-cost technique and small hardware, able to considerably improve the dispersion and the surface adhesion of multi-walled carbon nanotubes (CNTs) in epoxy resin with respect to amine-modified CNTs and as-received CNTs. Surface treatment of the CNTs is performed using hexamethylene diamine, or a mix of sulfuric and nitric acid, and one of two surfactants (for the diamine treatment on...
Coupled thermoviscoplasticity of glassy polymers in the logarithmic strain space based on the free volume theory
Miehe, Christian; Mendez Diez, Joel; Göktepe, Serdar; Schaenzel, Lisa Marie (Elsevier BV, 2011-06-15)
The paper outlines a constitutive model for finite thermo-visco-plastic behavior of amorphous glassy polymers and considers details of its numerical implementation. In contrast to existing kinematical approaches to finite plasticity of glassy polymers, the formulation applies a plastic metric theory based on an additive split of Lagrangian Hencky-type strains into elastic and plastic parts. The analogy between the proposed formulation in the logarithmic strain space and the geometrically linear theory of pl...
Mixed-mode fracture analysis of orthotropic functionally graded materials under mechanical and thermal loads
Dağ, Serkan; Sarikaya, Duygu (Elsevier BV, 2007-12-01)
Mixed-mode fracture problems of orthotropic functionally graded materials (FGMs) are examined under mechanical and thermal loading conditions. In the case of mechanical loading, an embedded crack in an orthotropic FGM layer is considered. The crack is assumed to be loaded by arbitrary normal and shear tractions that are applied to its surfaces. An analytical solution based on the singular integral equations and a numerical approach based on the enriched finite elements are developed to evaluate the mixed-mo...
Inclusion induced anisotropy of short fatigue crack growth in steel
Kaynak, Cevdet; Baker, TJ (Informa UK Limited, 1996-07-01)
In this study, the growth behaviour of short fatigue cracks in En7A steel with a high content of elongated MnS inclusions was investigated by generating and evaluating the short crack data under different loading conditions for the six principal specimen orientations. Short cracks showed a strong anisotropic behaviour in which they grew much faster in the transverse and short transverse orientations than in the longitudinal orientations in all fatigue processes. This was due to the relatively high content o...
Citation Formats
S. E. Toktaş and S. Dağ, “Oblique surface cracking and crack closure in an orthotropic medium under contact loading,” THEORETICAL AND APPLIED FRACTURE MECHANICS, pp. 0–0, 2020, Accessed: 00, 2020. [Online]. Available: https://hdl.handle.net/11511/69482.