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Dietmar Gross - One of the best experts on this subject based on the ideXlab platform.

  • 3376 - STUDY OF THE DYNAMIC INTERACTION BETWEEN A FAST RUNNING Crack AND AN INCLUSION USING THE TIME DOMAIN BEM
    2013
    Co-Authors: Wang Y.-s., J Leii, Dietmar Gross
    Abstract:

    ABSTRACT In this paper, a fast running Crack in an elastic matrix with an inclusion is studied by using the time domain boundary element method (BEM). The bi-material system is divided into two parts along the interface between the inclusion and the matrix. Each part is linear, elastic, homogeneous and isotropic. For the Crack surfaces, the non-hypersingular traction boundary integral equations are applied; while for the interface and external boundaries, traditional displacement boundary integral equations are used. In the numerical solution procedure, square root shape functions are adopted as to describe the proper asymptotic behavior in the vicinity of the Crack-Tips. The integrations over time are analytically computed via linear or constant temporal interpolation functions. The Crack growth is modeled by adding new elements of constant length to the Moving Crack Tip, which is controlled by the fracture criterion based on the maximum circumferential stress. The fracture criterion is evaluated to determine the direction and the speed of the Crack advance in each time step. As an example, a rectangular plate with a pre-existing edged Crack and a circular inclusion under the action of wedged impact loading is computed in details. The numerical results of the Crack growth path, running speed, dynamic stress intensity factors (DSIFs) and dynamic interface tractions are presented for various material combinations and geometries. The effects of the inclusion on the fast Crack propagation are discussed.

  • Numerical simulation of Crack deflection and penetration at an interface in a bi-material under dynamic loading by time-domain boundary element method
    International Journal of Fracture, 2008
    Co-Authors: Jun Lei, Yue-sheng Wang, Dietmar Gross
    Abstract:

    The hybrid time-domain boundary element method (BEM), together with the multi-region technique, is applied to simulate the dynamic process of Crack deflection/ penetration at an interface in a bi-material. The whole bi-material is divided into two regions along the interface. The traditional displacement boundary integral equations (BIEs) are employed with respect to the exterior boundaries; meanwhile, the non-hypersingular traction BIEs are used with respect to the part of the Crack in the matrix. Crack propagation along the interface is numerically modelled by releasing the nodes in the front of the Moving Crack Tip and Crack propagation in the matrix is modeled by adding new elements of constant length to the Moving Crack Tip. The dynamic behaviours of the Crack deflection/penetration at an interface, propagation in the matrix or along the interface and kinking out off the interface, are controlled by criteria developed from the quasi-static ones. The numerical results of the Crack growth trajectory for different inclined interface and bonded strength are computed and compared with the corresponding experimental results. Agreement between numerical and experimental results implies that the present time-domain BEM can provide a simulation for the dynamic propagation and deflection of a Crack in a bi-material.

  • Two dimensional numerical simulation of Crack kinking from an interface under dynamic loading by time domain boundary element method
    International Journal of Solids and Structures, 2007
    Co-Authors: Jun Lei, Yue-sheng Wang, Dietmar Gross
    Abstract:

    AbstractThe hybrid time-domain boundary element method, together with the multi-region technique, is applied to simulate the dynamic process of propagation and/or kinking of an interface Crack in a two-dimensional bi-material. The whole bi-material is divided into two regions along the interface. The traditional displacement boundary integral equations are employed with respect to each region. However, when the Crack kinks into the matrix material, the non-hypersingular traction boundary integral equations are used with respect to the part of the Crack in the matrix. Crack propagation along the interface is numerically modelled by releasing the nodes in the front of the Moving Crack-Tip controlled by the fracture criterion. Kinking of the interface Crack is controlled by a criterion developed from the quasi-static one. Once the Crack kinks into the matrix, its propagation is modeled by adding new elements of constant length to the Moving Crack-Tip controlled by a criterion extended from the quasi-static maximum circumferential stress. The numerical results of the Crack growth trajectory for different material combinations are computed and compared with the corresponding experimental results. Good agreement between numerical and experimental results implies that the present boundary element numerical method can provide an excellent simulation for the dynamic propagation and deflection of an interface Crack

  • Analysis of dynamic interaction between an inclusion and a nearby Moving Crack by BEM
    Engineering Analysis with Boundary Elements, 2005
    Co-Authors: Jun Lei, Yue-sheng Wang, Dietmar Gross
    Abstract:

    In this paper, the dynamic interaction between an inclusion and a nearby Moving Crack embedded in an elastic medium is studied by the boundary element method (BEM). To deal with this problem, the multi-region technique and two kinds of time-domain boundary integral equations (BIEs) are introduced. The system is divided into two parts along the interface between the inclusion and the matrix medium. Each part is linear, elastic, homogeneous and isotropic. The non-hypersingular traction boundary integral equation is applied on the Crack surfaces; while the traditional displacement boundary integral equation is used on the interface and external boundaries. In the numerical solution procedure, square root shape functions are adopted as to describe the proper asymptotic behavior in the vicinity of the Crack-Tips. The Crack growth is modeled by adding new elements of constant length to the Moving Crack Tip, which is controlled by the fracture criterion based on the maximum circumferential stress. In each time step, the direction and the speed of the Crack advance are evaluated. The numerical results of the Crack growth path, speed, dynamic stress intensity factors (DSIFs) and dynamic interface tractions for various material combinations and geometries are presented. The effect of the inclusion on the Moving Crack is discussed.

  • Time-domain BEM analysis of a rapidly growing Crack in a bi-material
    International Journal of Fracture, 2004
    Co-Authors: Jun Lei, Yue-sheng Wang, Dietmar Gross
    Abstract:

    Rapid propagation of a matrix Crack in a bi-material system is studied with emphasis on the dynamic interaction between the Crack and the interface by combining the traditional time-domain displacement boundary element method (BEM) and the non-hypersingular traction BEM. The Crack growth is controlled by the fracture criterion based on the maximum circumferential stress, and is modeled by adding new elements to the Moving Crack Tip. Detailed computation is performed for an unbounded bi-material with a Crack subjected to incident impact waves and a bounded rectangular bi-material plate under dynamic wedged loading. Numerical results of the Crack growth path, speed, dynamic stress intensity factors (DSIFs) and dynamic interface tractions are presented for various material combinations and geometries. The effects of the interface on the Crack growth are discussed.

Jun Lei - One of the best experts on this subject based on the ideXlab platform.

  • Crack propagation in matrix with inclusions by BEM
    2011 IEEE International Conference on Mechatronics and Automation, 2011
    Co-Authors: Yifeng Huang, Jun Lei, Qingsheng Yang
    Abstract:

    A time-domain boundary element method is applied to simulate the matrix Crack propagation in composite with inclusions under impact loading. The Crack-growth direction is determined by the maximum circumferential stress criterion, and the instantaneous velocity is approached by a bisection technique. New Crack-Tip elements of inconstant length are added to the Moving Crack-Tip to simulate the unsteady growth at each propagation time step. The interactions of a Crack with various clusters of inclusions are investigated.

  • Dynamic effects of inclusions and microCracks on a main Crack
    International Journal of Fracture, 2010
    Co-Authors: Jun Lei, Qingsheng Yang, Chuanzeng Zhang, Yue-sheng Wang
    Abstract:

    The shielding and amplification effects of mulTiple inclusions and microCracks on the Tip or the growth path of a main Crack under dynamic loading are investigated using numerical simulations. The simulations employ a combined numerical tool based on the time-domain boundary element method together with the sub-region technique for multi-regions, the maximum circumferential stress criterion for Crack-growth direction and discrete modelling for the Crack propagation. New elements of constant length are added to the Moving Crack-Tip to simulate the growth at an adaptable time-step according to the Crack propagation criterion. Of particular interest is the study of the effects of the sizes and positions of inclusions and microCracks and the material combinations on the dynamic stress intensity factors and the Crack growth path. The numerical results demonstrate the Crack-Tip shielding and amplification effects of inclusions and micro-Cracks.

  • Numerical simulation of Crack deflection and penetration at an interface in a bi-material under dynamic loading by time-domain boundary element method
    International Journal of Fracture, 2008
    Co-Authors: Jun Lei, Yue-sheng Wang, Dietmar Gross
    Abstract:

    The hybrid time-domain boundary element method (BEM), together with the multi-region technique, is applied to simulate the dynamic process of Crack deflection/ penetration at an interface in a bi-material. The whole bi-material is divided into two regions along the interface. The traditional displacement boundary integral equations (BIEs) are employed with respect to the exterior boundaries; meanwhile, the non-hypersingular traction BIEs are used with respect to the part of the Crack in the matrix. Crack propagation along the interface is numerically modelled by releasing the nodes in the front of the Moving Crack Tip and Crack propagation in the matrix is modeled by adding new elements of constant length to the Moving Crack Tip. The dynamic behaviours of the Crack deflection/penetration at an interface, propagation in the matrix or along the interface and kinking out off the interface, are controlled by criteria developed from the quasi-static ones. The numerical results of the Crack growth trajectory for different inclined interface and bonded strength are computed and compared with the corresponding experimental results. Agreement between numerical and experimental results implies that the present time-domain BEM can provide a simulation for the dynamic propagation and deflection of a Crack in a bi-material.

  • Two dimensional numerical simulation of Crack kinking from an interface under dynamic loading by time domain boundary element method
    International Journal of Solids and Structures, 2007
    Co-Authors: Jun Lei, Yue-sheng Wang, Dietmar Gross
    Abstract:

    AbstractThe hybrid time-domain boundary element method, together with the multi-region technique, is applied to simulate the dynamic process of propagation and/or kinking of an interface Crack in a two-dimensional bi-material. The whole bi-material is divided into two regions along the interface. The traditional displacement boundary integral equations are employed with respect to each region. However, when the Crack kinks into the matrix material, the non-hypersingular traction boundary integral equations are used with respect to the part of the Crack in the matrix. Crack propagation along the interface is numerically modelled by releasing the nodes in the front of the Moving Crack-Tip controlled by the fracture criterion. Kinking of the interface Crack is controlled by a criterion developed from the quasi-static one. Once the Crack kinks into the matrix, its propagation is modeled by adding new elements of constant length to the Moving Crack-Tip controlled by a criterion extended from the quasi-static maximum circumferential stress. The numerical results of the Crack growth trajectory for different material combinations are computed and compared with the corresponding experimental results. Good agreement between numerical and experimental results implies that the present boundary element numerical method can provide an excellent simulation for the dynamic propagation and deflection of an interface Crack

  • Analysis of dynamic interaction between an inclusion and a nearby Moving Crack by BEM
    Engineering Analysis with Boundary Elements, 2005
    Co-Authors: Jun Lei, Yue-sheng Wang, Dietmar Gross
    Abstract:

    In this paper, the dynamic interaction between an inclusion and a nearby Moving Crack embedded in an elastic medium is studied by the boundary element method (BEM). To deal with this problem, the multi-region technique and two kinds of time-domain boundary integral equations (BIEs) are introduced. The system is divided into two parts along the interface between the inclusion and the matrix medium. Each part is linear, elastic, homogeneous and isotropic. The non-hypersingular traction boundary integral equation is applied on the Crack surfaces; while the traditional displacement boundary integral equation is used on the interface and external boundaries. In the numerical solution procedure, square root shape functions are adopted as to describe the proper asymptotic behavior in the vicinity of the Crack-Tips. The Crack growth is modeled by adding new elements of constant length to the Moving Crack Tip, which is controlled by the fracture criterion based on the maximum circumferential stress. In each time step, the direction and the speed of the Crack advance are evaluated. The numerical results of the Crack growth path, speed, dynamic stress intensity factors (DSIFs) and dynamic interface tractions for various material combinations and geometries are presented. The effect of the inclusion on the Moving Crack is discussed.

Yue-sheng Wang - One of the best experts on this subject based on the ideXlab platform.

  • Dynamic effects of inclusions and microCracks on a main Crack
    International Journal of Fracture, 2010
    Co-Authors: Jun Lei, Qingsheng Yang, Chuanzeng Zhang, Yue-sheng Wang
    Abstract:

    The shielding and amplification effects of mulTiple inclusions and microCracks on the Tip or the growth path of a main Crack under dynamic loading are investigated using numerical simulations. The simulations employ a combined numerical tool based on the time-domain boundary element method together with the sub-region technique for multi-regions, the maximum circumferential stress criterion for Crack-growth direction and discrete modelling for the Crack propagation. New elements of constant length are added to the Moving Crack-Tip to simulate the growth at an adaptable time-step according to the Crack propagation criterion. Of particular interest is the study of the effects of the sizes and positions of inclusions and microCracks and the material combinations on the dynamic stress intensity factors and the Crack growth path. The numerical results demonstrate the Crack-Tip shielding and amplification effects of inclusions and micro-Cracks.

  • Numerical simulation of Crack deflection and penetration at an interface in a bi-material under dynamic loading by time-domain boundary element method
    International Journal of Fracture, 2008
    Co-Authors: Jun Lei, Yue-sheng Wang, Dietmar Gross
    Abstract:

    The hybrid time-domain boundary element method (BEM), together with the multi-region technique, is applied to simulate the dynamic process of Crack deflection/ penetration at an interface in a bi-material. The whole bi-material is divided into two regions along the interface. The traditional displacement boundary integral equations (BIEs) are employed with respect to the exterior boundaries; meanwhile, the non-hypersingular traction BIEs are used with respect to the part of the Crack in the matrix. Crack propagation along the interface is numerically modelled by releasing the nodes in the front of the Moving Crack Tip and Crack propagation in the matrix is modeled by adding new elements of constant length to the Moving Crack Tip. The dynamic behaviours of the Crack deflection/penetration at an interface, propagation in the matrix or along the interface and kinking out off the interface, are controlled by criteria developed from the quasi-static ones. The numerical results of the Crack growth trajectory for different inclined interface and bonded strength are computed and compared with the corresponding experimental results. Agreement between numerical and experimental results implies that the present time-domain BEM can provide a simulation for the dynamic propagation and deflection of a Crack in a bi-material.

  • Two dimensional numerical simulation of Crack kinking from an interface under dynamic loading by time domain boundary element method
    International Journal of Solids and Structures, 2007
    Co-Authors: Jun Lei, Yue-sheng Wang, Dietmar Gross
    Abstract:

    AbstractThe hybrid time-domain boundary element method, together with the multi-region technique, is applied to simulate the dynamic process of propagation and/or kinking of an interface Crack in a two-dimensional bi-material. The whole bi-material is divided into two regions along the interface. The traditional displacement boundary integral equations are employed with respect to each region. However, when the Crack kinks into the matrix material, the non-hypersingular traction boundary integral equations are used with respect to the part of the Crack in the matrix. Crack propagation along the interface is numerically modelled by releasing the nodes in the front of the Moving Crack-Tip controlled by the fracture criterion. Kinking of the interface Crack is controlled by a criterion developed from the quasi-static one. Once the Crack kinks into the matrix, its propagation is modeled by adding new elements of constant length to the Moving Crack-Tip controlled by a criterion extended from the quasi-static maximum circumferential stress. The numerical results of the Crack growth trajectory for different material combinations are computed and compared with the corresponding experimental results. Good agreement between numerical and experimental results implies that the present boundary element numerical method can provide an excellent simulation for the dynamic propagation and deflection of an interface Crack

  • Analysis of dynamic interaction between an inclusion and a nearby Moving Crack by BEM
    Engineering Analysis with Boundary Elements, 2005
    Co-Authors: Jun Lei, Yue-sheng Wang, Dietmar Gross
    Abstract:

    In this paper, the dynamic interaction between an inclusion and a nearby Moving Crack embedded in an elastic medium is studied by the boundary element method (BEM). To deal with this problem, the multi-region technique and two kinds of time-domain boundary integral equations (BIEs) are introduced. The system is divided into two parts along the interface between the inclusion and the matrix medium. Each part is linear, elastic, homogeneous and isotropic. The non-hypersingular traction boundary integral equation is applied on the Crack surfaces; while the traditional displacement boundary integral equation is used on the interface and external boundaries. In the numerical solution procedure, square root shape functions are adopted as to describe the proper asymptotic behavior in the vicinity of the Crack-Tips. The Crack growth is modeled by adding new elements of constant length to the Moving Crack Tip, which is controlled by the fracture criterion based on the maximum circumferential stress. In each time step, the direction and the speed of the Crack advance are evaluated. The numerical results of the Crack growth path, speed, dynamic stress intensity factors (DSIFs) and dynamic interface tractions for various material combinations and geometries are presented. The effect of the inclusion on the Moving Crack is discussed.

  • Time-domain BEM analysis of a rapidly growing Crack in a bi-material
    International Journal of Fracture, 2004
    Co-Authors: Jun Lei, Yue-sheng Wang, Dietmar Gross
    Abstract:

    Rapid propagation of a matrix Crack in a bi-material system is studied with emphasis on the dynamic interaction between the Crack and the interface by combining the traditional time-domain displacement boundary element method (BEM) and the non-hypersingular traction BEM. The Crack growth is controlled by the fracture criterion based on the maximum circumferential stress, and is modeled by adding new elements to the Moving Crack Tip. Detailed computation is performed for an unbounded bi-material with a Crack subjected to incident impact waves and a bounded rectangular bi-material plate under dynamic wedged loading. Numerical results of the Crack growth path, speed, dynamic stress intensity factors (DSIFs) and dynamic interface tractions are presented for various material combinations and geometries. The effects of the interface on the Crack growth are discussed.

A J Rosakis - One of the best experts on this subject based on the ideXlab platform.

  • transonic Crack growth along a bimaterial interface an investigation of the asymptotic structure of near Tip fields
    International Journal of Solids and Structures, 1996
    Co-Authors: Yonggang Huang, A J Rosakis
    Abstract:

    Abstract Transonic interfacial Crack growth in bimaterial systems is analysed, and the asymptotic field around the Moving Crack Tip is obtained by the straightforward approach of analytic continuation. The power of singularity is less than 1/2 for anti-plane shear deformation. For in-plane deformation, the power of singularity can be real or complex, depending on the speed of the Crack Tip. Across the Rayleigh wave speed, the real part of the power has a jump of −1/2, and the imaginary part approaches infinity. The stresses are singular, not only around the Crack Tip, but also on an entire ray Moving with the Crack Tip. These observations are illustrated by examples using PMMA/steel and Al/Al 2 O 3 bimaterial systems.

  • determination of temperature field around a rapidly Moving Crack Tip in an elastic plastic solid
    International Journal of Heat and Mass Transfer, 1996
    Co-Authors: Xiaomin Deng, A J Rosakis
    Abstract:

    Abstract The problem of local heating and temperature rise induced by dynamic Crack growth in elastic-plastic solids is studied numerically. Heat generation caused by plastic work dissipation is estimated from Crack-Tip stress and deformation fields obtained separately by two of the authors. The temperature field in an Eulerian description is shown to be governed by a convection-dominated flow equation with a singular source term that is distributed over an irregular Crack-Tip region, the active plastic zone. The peak value and spatial distribution of the temperature increase are determined using two independent computer codes, which are developed by the authors based on an integral representation of the temperature field and on an upwind finite element formulation. The accuracy and reliability of the numerical methods and their solutions are studied carefully against exact, closed-form solutions for several specially designed boundary value problems. These methods are used to simulate dynamic fracture tests on AISI 4340 steel specimens, and the predicted temperature contours and maximum values are found to be in good agreement with those measured and estimated experimentally.

Sunil Saigal - One of the best experts on this subject based on the ideXlab platform.

  • An Element Free Galerkin analysis of steady dynamic growth of a mode i Crack in elastic–plastic materials
    International Journal of Solids and Structures, 1999
    Co-Authors: Sunil Saigal
    Abstract:

    Abstract An Element Free Galerkin (EFG) method based formulation for steady dynamic Crack growth in elastic–plastic materials is developed. A domain convecting parallel to the steadily Moving Crack Tip is employed. The EFG methodology eliminates the stringent mesh requirements of the Finite Element Method (FEM) for such problems. Both rate-independent materials and rate-dependent materials are considered. The material is characterized by von Mises yielding condition and an associated flow rule. For rate-independent materials, both the influence of Crack speeds and that of strain hardening on the mechanics of steady dynamic Crack growth are investigated. For rate-dependent materials, only a non-hardening material is considered with emphasis on determining the influence of viscous properties of materials and Crack speeds. The influence of strain hardening on steady dynamic Crack growth shows the same trends as for steady quasi-static Crack growth. The simplifications used in the literature in deriving analytical solutions for high strain-rate Crack growth have been examined thoroughly using the numerical results.