Papers by Keyword: Bimaterial Interface

Abstract: In the contribution the limits of the validity of classical linear elastic fracture mechanics are extended to problems connected with failure of composite structures. The work is focused mainly on the case of a crack touching the interface between two different materials, two different constituents. The approach suggested in the paper facilitates the answer to the question what is the influence of particle (in particulate composite) or layer (in laminates) on crack propagation through bimaterial interface. Different composite (bimaterial) structures are considered: layered composites and composites reinforced by particles. The presented approach follows the basic idea of linear elastic fracture mechanics, i.e. the validity of small scale yielding conditions is assumed, and has a phenomenological character.

Abstract: The evaluation of the stress singularities and generalised stress intensity factor (GSIF) for the case of an inclined surface crack terminating perpendicular to the interface between two orthotropic materials is considered. The knowledge of the regular and auxiliary solution allows evaluating the GSIF using the reciprocal theorem (Ψ-integral). A co-operating effect of a stronger and a weaker singular stress field for a crack impinging a bimaterial interface is investigated.

Abstract: Composite materials or generally materials with interfaces are nowadays used in many varied engineering applications. In comparison with classical engineering materials the existence of material interface causes locally different stress distribution, which can strongly influence behaviour of whole structure and can have an important influence on failure mechanisms of such materials. The paper presented is devoted to the investigation of stress singularity exponents of a crack growing in a bimaterial body perpendicularly to the interface and touching the material interface. Discrepancies between value of stress singularity exponent in the centre of bimaterial body and on the free surface were found. The assumptions of linear elastic fracture mechanics (LEFM) and small scale yielding (SSY) are considered. For numerical calculations finite element analysis was used. Results obtained can contribute to a better understanding of failure of materials with interfaces.

Abstract: A steady-state subsonic interface crack propagating between an elastic solid and a rigid substrate with crack face contact is studied. Two cases with respective to the contact length are considered, i.e., semi-infinite and finite crack face contact. Different from a stationary or an open subsonic interface crack, stress singularity at the crack tip in the present paper is found to be non-oscillatory. Furthermore, in the semi-infinite contact case, the singularity of the stress field near the crack tip is less than 1/2. In the finite contact case, no singularity exists near the crack tip, but less than 1/2 singularity does at the end of the contact zone. In both cases, the singularity depends on the linear contact coefficient and the crack speed. Asymptotic solutions near the crack tip are given and analyzed. In order to satisfy the contact conditions, reasonable region of the linear contact coefficient is found. In addition, the solution predicts a non-zero-energy dissipation rate due to crack face contact.

Abstract: Fracture along an interface between materials plays a major role in failure of material. In this investigation, finite element calculations with Kachanov–Rabotnov damage law were carried out to study the creep damage distribution near the interface cavity in bimaterial specimens. The specimens with central hole were divided into three types. The material parameters of K-R law used in this paper were chosen for a brittle material and ductile material. All calculations were performed under four load cases. Due to the difference between elastic moduli of the bounded materials, the elastic stress field as a function of the Young’s modulus ratio (R=E1/E2) was determined. At the same time, the influence of model type on elastic stress distribution near the cavity was considered. Under the same conditions, the material with larger modulus is subjected to larger stress. The creep damage calculations show that the location of the maximum damage is different for each model. The distributions of creep damage for all three models are dependent on the material properties and load cases.