Papers by Keyword: Interface Crack

Abstract: The bimaterial sample was analyzed to determine the three-dimensional zone at the interface crack tip and the field in the plane stress state. The solutions for the complete 3D field in different zones around the crack tip were approximated by the plane stress and plane strain states' asymptotic solutions. The difference between the solutions for the plane stress and plane strain states is defined by the three variables. The established relationship between the far field and the field around the crack tip in the plane strain conditions, enables relating the measured experimental results of the stress intensity factor to results for the stress intensity factor for the field around the crack tip, which represent the more relevant parameter for formulating the fracture criterion.

Abstract: In the paper, the crack parallel to and lying on the interface in the hard cermet cladding material structure is taken as the study object. Theoretical models of the stress intensity factor (SIF) of the interface crack under steady mechanical-thermal coupled loads are built. Based on which the interface crack SIFs in the cermet cladding material of 5Cr2Ni08C/Q235 under the same loads are analyzed with the finite element method. The crack SIF change laws under the coupled loads are obtained. K_I increases with the increase of the temperature, the mechanical load and the crack length respectively. The absolute values of K_II have the same change laws. And K_I corresponding to the coupled loads is bigger than that to the single load. The research results are very important to develop the interface crack propagation theory. And they will also improve the optimization designs of the hard cladding material parts, and expand their applications.

Abstract: Interface crack is evaluated using modified quarter point crack tip displacement method. Quarter point elements around the crack tip were employed in the Finite Element (ABAQUS) analysis to determine the near crack tip grid point displacements. In this study, a technique is adopted in which the crack opening displacement of the near crack tip grid point is forced to satisfy a known constraint. The linear term in the distance around the crack tip is reduced to zero. The complex stress intensity factor for interface crack is determined using the quarter point and the displacement correlation technique. It is well observed that FEM produce a less reliable displacement approximation around interface crack tip. However, this report will show that the use of near crack tip open displacement as determined by the standard finite element method can be utilised to give satisfactory result for the interface stress intensity factors K₁ and K₂.

Abstract: The goal of the contribution is to develop an asymptotic interface crack-tip solution under conditions of plane strain for a bi-material that obeys a special form of linear isotropic gradient elasticity. Several fracture mechanics problems have been solved in the past within the framework of strain gradient elasticity which is capable to capture additional length/size parameters. However to our best knowledge no solution concerning an interface crack is available in the literature.

Abstract: The interface of the ternary boride hard cladding material consists of hard phase (Mo₂FeB₂) and bonding phase (α-Fe). In this paper, on the basis of the ideal interface model of Mo₂FeB₂ (100)/α-Fe (001) built with the molecular dynamics software, the Mo₂FeB₂ (100)/α-Fe (001) interface models with micro-cracks parallel with the interface, normal to the interface, and inclined to the interface have been built separately. The interface bonding energies of these four different interface models have been calculated, which shows that the interface model with the micro crack inclined to the interface has the biggest interface bonding energy, while the interface model with the micro crack parallel with the interface has the smallest bonding energy, the interface crack will be the most easily to propagate. The change rule of bonding energy of the interface model with the micro crack parallel with the interface with different lengths has been simulated and analyzed.

Abstract: The finite element method combined with the singular element was adopted to study the effects of thickness ratio of the coating-matrix, elastic modulus ratio of the coating-matrix, and the ratio of ensile stress and shear stress on the coating top on the stress intensity of the interface crack on the coating-matrix. Through calculations, results show that elastic modulus ratio of the coating-matrix has little effect on stress intensity factor of interface crack, while the thickness ratio and the tensile stress and shear stress ratio on the coating top have a great effect on it, which should be controlled in the coating-matrix structure design.

Abstract: By application of the theory of complex variable functions, dynamic propagation problems concerning symmetrical mode III interface crack of Aluminum alloys were investigated. The problems dealt with can be very facilely translated into Riemann-Hilbert problem by the approaches of self-similar functions, and the universal representations of analytical solutions of the stresses, displacements and dynamic stress intensity factors for the surfaces of symmetrical mode III interface crack subjected to motive increasing loadings Pt⁵/x⁵ and Px⁶/t⁵ were attained, respectively. After those solutions were utilized by superposition principle, the solutions of discretionally complicated problems could be easily acquired.

Abstract: The propagation behavior of crack with different initiation position is affected by the constraint effect differences in dissimilar weld joints mechanical heterogeneity. The ductile fracture model of interface crack in dissimilar weld joints was built by adopting extended finite element method; the propagation characteristic of interface crack was summarized. The results indicate that the strength mismatch of materials at sides of interface will increase trend of crack advancing into the relative soft material which has lower yield strength and lower hardening exponent.

Abstract: Relations between different solutions of an interface crack in a neighborhood of the crack tip given by the open model, frictionless and frictional contact models of interface cracks are analyzed numerically for a penny-shaped interface crack subjected to remote tension. A new analytic expression for the size of the near-tip contact zone in presence of Coulomb friction between crack faces is proposed in the so-called case of the contact zone field embedded in the oscillatory field.

Abstract: A two-scale method able to carry out a macroscopic failure analysis of a composite structure in presence of microscopic mixed mode interface crack initiation, is proposed. The method is able to accurately predict local failure quantities (fiber/matrix interfacial stresses, energy release and mode mixity for an interface crack) in an arbitrary cell from the results of a macroscopic homogenized analysis. Microscopic crack initiation is thus analyzed by using a coupled stress and energy failure criterion in term of these local quantities. Numerical results are obtained for a plane strain model of a locally periodic fiber-reinforced composite material subjected to shear loading and characterized by initially undamaged fiber/matrix interfaces. Predictions for the critical load factor and interface crack length at crack onset obtained by the proposed model are compared with those obtained by means of a direct simulation.