The Experts below are selected from a list of 43884 Experts worldwide ranked by ideXlab platform
Hai-yun Sun - One of the best experts on this subject based on the ideXlab platform.
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Research on Vehicle Accident Simulation Based on Multi-source Information Combined
DEStech Transactions on Computer Science and Engineering, 2017Co-Authors: Wei Zhao, Yan-hui Fan, Hai-yun SunAbstract:The real vehicle accident case is selected, and accident multi-source data such as vehicle Damage Deformation, vehicle final position, scene ground traces, scattered objects, occupant injury and so on are combined in the paper. The vehicle model and road environment model are built on the basis of PC-Crash software. In order to reproduce real accident, the vehicle collision dynamics and kinematics parameters are analyzed by vehicle dynamics simulation, moreover, occupant collision injury and its cause involving vehicle accident are analyzed through human trauma assessment software. The methodology based on multi-source accident information combined in this paper is applied on real accident and validated the practicality and effectiveness on simulation and reconstruction, which is of great value in research on vehicle accident.
Taehyo Park - One of the best experts on this subject based on the ideXlab platform.
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The kinematics of Damage for finite-strain elasto-plastic solids
International Journal of Engineering Science, 1999Co-Authors: George Z. Voyiadjis, Taehyo ParkAbstract:In this paper the kinematics of Damage for finite strain, elasto-plastic Deformation is introduced using the fourth-order Damage effect tensor through the concept of the effective stress within the framework of continuum Damage mechanics. In the absence of the kinematic description of Damage Deformation leads one to adopt one of the following two different hypotheses for the small Deformation problems. One uses either the hypothesis of strain equivalence or the hyphothesis of energy equivalence in order to characterize the Damage of the material. The proposed approach in this work provides a general description of kinematics of Damage applicable to finite strains. This is accomplished by directly considering the kinematics of the Deformation field and furthermore it is not confined to small strains as in the case of the strain equivalence or the strain energy equivalence approaches. In this work, the Damage is described kinematically in both the elastic domain and plastic domain using the fourth order Damage effect tensor which is a function of the second-order Damage tensor. The Damage effect tensor is explicitly characterized in terms of a kinematic measure of Damage through a second-order Damage tensor. Two kinds of second-order Damage tensor representations are used in this work with respect to two reference configurations. The finite elasto-plastic Deformation behavior with Damage is also viewed here within the framework of thermodynamics with internal state variables. Using the consistent thermodynamic formulation one introduces seperately the strain due to Damage and the associated dissipation energy due to this strain.
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Kinematic Description of Damage
Journal of Applied Mechanics, 1998Co-Authors: Taehyo Park, George Z. VoyiadjisAbstract:In this paper the kinematics of Damage for finite elastic Deformations is introduced using the fourth-order Damage effect tensor through the concept of the effective stress within the framework of continuum Damage mechanics. However, the absence of the kinematic description of Damage Deformation leads one to adopt one of the following two different hypotheses. One uses either the hypothesis of strain equivalence or the hypothesis of energy equivalence in order to characterize the Damage of the material. The proposed approach in this work provides a relation between the effective strain and the Damage elastic strain that is also applicable to finite strains. This is accomplished in this work by directly considering the kinematics of the Deformation field and furthermore it is not confined to small strains as in the case of the strain equivalence or the strain energy equivalence approaches. The proposed approach shows that it is equivalent to the hypothesis of energy equivalence for finite strains. In this work, the Damage is described kinematically in the elastic domain using the fourth-order Damage effect tensor which is a function of the second-order Damage tensor. The Damage effect tensor is explicitly characterized in terms of a kinematic measure ofDamage through a second-order Damage tensor. The constitutive equations of the elastic-Damage behavior are derived through the kinematics of Damage using the simple mapping instead of the other two hypotheses.
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Kinematics of large elastoplastic Damage Deformation
Damage Mechanics in Engineering Materials, 1998Co-Authors: George Z. Voyiadjis, Taehyo ParkAbstract:Abstract In this paper the kinematics of Damage for finite strain, elasto-plastic Deformation is introduced using the fourth-order Damage effect tensor through the concept of the effective stress within the framework of continuum Damage mechanics. In the absence of the kinematic description of Damage Deformation leads one to adopt one of the following two different hypotheses for the small Deformation problems. One uses either the hypothesis of strain equivalence or the hyphothesis of energy equivalence in order to characterize the Damage of the material. The proposed approach in this work provides a general description of kinematics of Damage applicable to finite strains. This is accomplished by directly considering the kinematics of the Deformation field and furthermore it is not confined to small strains as in the case of the strain equivalence or the strain energy equivalence approaches. In this work, the Damage is described kinematically in both the elastic domain and plastic domain using the fourth order Damage effect tensor which is a function of the second-order Damage tensor. The Damage effect tensor is explicitly characterized in terms of a kinematic measure of Damage through a second-order Damage tensor. Two kinds of second-order Damage tensor representations are used in this work with respect to two reference configurations. The finite elasto-plastic Deformation behavior with Damage is also viewed here within the framework of thermodynamics with internal state variables. Using the consistent thermodynamic formulation one introduces seperately the strain due to Damage and the associated dissipation energy due to this strain.
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Anisotropic Damage Effect Tensors for the Symmetrization of the Effective Stress Tensor
Journal of Applied Mechanics, 1997Co-Authors: George Z. Voyiadjis, Taehyo ParkAbstract:Based on the concept of the effective stress and on the description of anisotropic Damage Deformation within the framework of continuum Damage mechanics, a fourth order Damage effective tensor is properly defined. For a general state of Deformation and Damage, it is seen that the effective stress tensor is usually asymmetric. Its symmetrization is necessary for a continuum theory to be valid in the classical sense. In order to transform the current stress tensor to a symmetric effective stress tensor, a fourth order Damage effect tensor should be defined such that it follows the rules of tensor algebra and maintains a physical description of Damage. Moreover, an explicit expression of the Damage effect tensor is of particular importance in order to obtain the constitutive relation in the Damaged material. The Damage effect tensor in this work is explicitly characterized in terms of kinematic measure of Damage through a second-order Damage tensor. In this work, tensorial forms are used for the derivation of such a linear transformation tensor which is then converted to a matrix form.
V. M. Fomin - One of the best experts on this subject based on the ideXlab platform.
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The influence of the surface on the fracture process of nanostructures under dynamic loads
Computational Materials Science, 2015Co-Authors: E. I. Golovneva, Igor Golovnev, V. M. FominAbstract:Abstract In this paper, the authors conducted a study of the free surface effect on the process of Damage, Deformation and fracture of metallic nanoclusters. In particular, a detailed study of the dynamic processes in systems of surface and bulk atoms in a metallic copper crystal caused by the movement of one of the external borders of the crystal at a constant velocity was conducted.
George Z. Voyiadjis - One of the best experts on this subject based on the ideXlab platform.
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The kinematics of Damage for finite-strain elasto-plastic solids
International Journal of Engineering Science, 1999Co-Authors: George Z. Voyiadjis, Taehyo ParkAbstract:In this paper the kinematics of Damage for finite strain, elasto-plastic Deformation is introduced using the fourth-order Damage effect tensor through the concept of the effective stress within the framework of continuum Damage mechanics. In the absence of the kinematic description of Damage Deformation leads one to adopt one of the following two different hypotheses for the small Deformation problems. One uses either the hypothesis of strain equivalence or the hyphothesis of energy equivalence in order to characterize the Damage of the material. The proposed approach in this work provides a general description of kinematics of Damage applicable to finite strains. This is accomplished by directly considering the kinematics of the Deformation field and furthermore it is not confined to small strains as in the case of the strain equivalence or the strain energy equivalence approaches. In this work, the Damage is described kinematically in both the elastic domain and plastic domain using the fourth order Damage effect tensor which is a function of the second-order Damage tensor. The Damage effect tensor is explicitly characterized in terms of a kinematic measure of Damage through a second-order Damage tensor. Two kinds of second-order Damage tensor representations are used in this work with respect to two reference configurations. The finite elasto-plastic Deformation behavior with Damage is also viewed here within the framework of thermodynamics with internal state variables. Using the consistent thermodynamic formulation one introduces seperately the strain due to Damage and the associated dissipation energy due to this strain.
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Kinematic Description of Damage
Journal of Applied Mechanics, 1998Co-Authors: Taehyo Park, George Z. VoyiadjisAbstract:In this paper the kinematics of Damage for finite elastic Deformations is introduced using the fourth-order Damage effect tensor through the concept of the effective stress within the framework of continuum Damage mechanics. However, the absence of the kinematic description of Damage Deformation leads one to adopt one of the following two different hypotheses. One uses either the hypothesis of strain equivalence or the hypothesis of energy equivalence in order to characterize the Damage of the material. The proposed approach in this work provides a relation between the effective strain and the Damage elastic strain that is also applicable to finite strains. This is accomplished in this work by directly considering the kinematics of the Deformation field and furthermore it is not confined to small strains as in the case of the strain equivalence or the strain energy equivalence approaches. The proposed approach shows that it is equivalent to the hypothesis of energy equivalence for finite strains. In this work, the Damage is described kinematically in the elastic domain using the fourth-order Damage effect tensor which is a function of the second-order Damage tensor. The Damage effect tensor is explicitly characterized in terms of a kinematic measure ofDamage through a second-order Damage tensor. The constitutive equations of the elastic-Damage behavior are derived through the kinematics of Damage using the simple mapping instead of the other two hypotheses.
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Kinematics of large elastoplastic Damage Deformation
Damage Mechanics in Engineering Materials, 1998Co-Authors: George Z. Voyiadjis, Taehyo ParkAbstract:Abstract In this paper the kinematics of Damage for finite strain, elasto-plastic Deformation is introduced using the fourth-order Damage effect tensor through the concept of the effective stress within the framework of continuum Damage mechanics. In the absence of the kinematic description of Damage Deformation leads one to adopt one of the following two different hypotheses for the small Deformation problems. One uses either the hypothesis of strain equivalence or the hyphothesis of energy equivalence in order to characterize the Damage of the material. The proposed approach in this work provides a general description of kinematics of Damage applicable to finite strains. This is accomplished by directly considering the kinematics of the Deformation field and furthermore it is not confined to small strains as in the case of the strain equivalence or the strain energy equivalence approaches. In this work, the Damage is described kinematically in both the elastic domain and plastic domain using the fourth order Damage effect tensor which is a function of the second-order Damage tensor. The Damage effect tensor is explicitly characterized in terms of a kinematic measure of Damage through a second-order Damage tensor. Two kinds of second-order Damage tensor representations are used in this work with respect to two reference configurations. The finite elasto-plastic Deformation behavior with Damage is also viewed here within the framework of thermodynamics with internal state variables. Using the consistent thermodynamic formulation one introduces seperately the strain due to Damage and the associated dissipation energy due to this strain.
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Anisotropic Damage Effect Tensors for the Symmetrization of the Effective Stress Tensor
Journal of Applied Mechanics, 1997Co-Authors: George Z. Voyiadjis, Taehyo ParkAbstract:Based on the concept of the effective stress and on the description of anisotropic Damage Deformation within the framework of continuum Damage mechanics, a fourth order Damage effective tensor is properly defined. For a general state of Deformation and Damage, it is seen that the effective stress tensor is usually asymmetric. Its symmetrization is necessary for a continuum theory to be valid in the classical sense. In order to transform the current stress tensor to a symmetric effective stress tensor, a fourth order Damage effect tensor should be defined such that it follows the rules of tensor algebra and maintains a physical description of Damage. Moreover, an explicit expression of the Damage effect tensor is of particular importance in order to obtain the constitutive relation in the Damaged material. The Damage effect tensor in this work is explicitly characterized in terms of kinematic measure of Damage through a second-order Damage tensor. In this work, tensorial forms are used for the derivation of such a linear transformation tensor which is then converted to a matrix form.
M. G. D. Geers - One of the best experts on this subject based on the ideXlab platform.
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An FFT-based spectral solver for interface decohesion modelling using a gradient Damage approach
Computational Mechanics, 2020Co-Authors: L. Sharma, R. H. J. Peerlings, P. Shanthraj, F. Roters, M. G. D. GeersAbstract:This work presents a fast Fourier transform (FFT) based method that can be used to model interface decohesion. The inability of an FFT solver to deal with sharp interfaces discards the use of conventional cohesive zones to model the interfacial mechanical behaviour within this framework. This limitation is overcome by approximating sharp interfaces (e.g. grain/phase boundaries) with an interphase. Within the interphase, the background plastic constitutive behaviour is inherited from the respective adjacent grains. The anisotropic kinematics of the decohesion process is modelled using a Damage Deformation gradient that is constructed by mapping the opening strains (in normal and tangential modes) to the associated projection tensors. The degradation (Damage) of the interfacial opening resistances is modelled via a dimensionless nonlocal Damage variable that prevents localisation of Damage within the interphase. This nonlocal variable results from the solution of a gradient Damage based regularisation equation within the interphase subdomain. The Damage field is constrained to the interphase region by applying a relatively large penalisation on the Damage gradients inside the interphase. The extent of nonlocality ensures that the Damage is largely uniform in the direction perpendicular to the interphase, thus making its thickness the theoretical lengthscale for dissipation. To achieve model predictions that are objective with respect to the interphase thickness, scaling relations of the model parameters are proposed. The numerical performance is shown for a uniform opening case and then for a propagating crack. Finally, an application to an artificial polycrystal is shown.
