The Experts below are selected from a list of 240 Experts worldwide ranked by ideXlab platform
D C Pham - One of the best experts on this subject based on the ideXlab platform.
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Rotating Plasticity and nonshakedown collapse modes for elastic–Plastic Bodies under cyclic loads
International Journal of Mechanical Sciences, 2016Co-Authors: Canh V Le, Trac D Tran, D C PhamAbstract:Abstract Different Plastic collapse modes may have different effects on the overall behaviour and load-bearing capacity of an elastic–Plastic structure subjected to variable loads, and they may even be determined by different material Plastic constants (for general Plastic hardening materials). Both lower bound static and upper bound reduced kinematic approaches have been implemented with appropriate finite element realizations and mathematical programming techniques to study the nonshakedown modes for elastic Plastic Bodies under cyclic loads. For sufficiently complex structure and loading program, it has been firstly demonstrated that an elastic–Plastic body may fail by rotating Plasticity collapse rather than the simpler alternating Plasticity one among other possible modes. That and other results also lead to interesting problems for further studies.
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rotating Plasticity and nonshakedown collapse modes for elastic Plastic Bodies under cyclic loads
International Journal of Mechanical Sciences, 2016Co-Authors: Canh V Le, Trac D Tran, D C PhamAbstract:Abstract Different Plastic collapse modes may have different effects on the overall behaviour and load-bearing capacity of an elastic–Plastic structure subjected to variable loads, and they may even be determined by different material Plastic constants (for general Plastic hardening materials). Both lower bound static and upper bound reduced kinematic approaches have been implemented with appropriate finite element realizations and mathematical programming techniques to study the nonshakedown modes for elastic Plastic Bodies under cyclic loads. For sufficiently complex structure and loading program, it has been firstly demonstrated that an elastic–Plastic body may fail by rotating Plasticity collapse rather than the simpler alternating Plasticity one among other possible modes. That and other results also lead to interesting problems for further studies.
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shakedown analysis for elastic Plastic Bodies with limited kinematic hardening
Proceedings of The Royal Society A: Mathematical Physical and Engineering Sciences, 2001Co-Authors: D C Pham, Dieter WeichertAbstract:A shakedown theory for elastic–Plastic Bodies with limited kinematic hardening (Prager's linear kinematic hardening rule is assumed) is developed, which indicates that the Plastic modulus should not influence the shakedown behaviour of structures. A reduced kinematic inadaptation theorem without time integrals is deduced, which is separated into incremental and alternating Plasticity collapse criteria. The yield limit for the alternating Plasticity collapse mode is taken according to particular loading processes from low–cycle to high–cycle ones, or as the lowest one of the fatigue limit. Shakedown behaviour of a spherical shell under quasistatic as well as quasi–periodic dynamic loads illustrates the results.
Pham Duc Chinh - One of the best experts on this subject based on the ideXlab platform.
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Shakedown kinematic theorem for elastic–perfectly Plastic Bodies
International Journal of Plasticity, 2020Co-Authors: Pham Duc ChinhAbstract:Abstract The classical shakedown kinematic theorem due to Koiter for elastic–perfectly Plastic Bodies is re-examined and divided into separated shakedown and nonshakedown theorems. While the shakedown theorem is based on the set of Koiter's Plastic strain rate cycles, the non-shakedown one involves a broader set of admissible Plastic strain rate cycles, the end-cycle accumulated strains of which are deviatoric parts of compatible strain fields. For certain broad classes of practical problems the two statements are unified to yield the unique theorem in Koiter's sense.
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Shakedown theory for elastic-perfectly Plastic Bodies revisited
International Journal of Mechanical Sciences, 2003Co-Authors: Pham Duc ChinhAbstract:Abstract Yield criteria for elastic-perfectly Plastic solids, in particular, the Mises and Tresca ones, permit unlimited hydrostatic stresses, leading to some singularity in the classical Melan–Koiter shakedown theory. Classical shakedown theory is re-examined regarding this problem. It is shown that the complete proofs of both static and kinematic theorems require restrictions on the hydrostatic stresses. A modified shakedown kinematic theorem using a fictitious material that can yield in bulk tension and compression has been constructed for subsequent treatment of real engineering materials, which cannot yield but fail under high hydrostatic stresses. The kinematic theorem should have vanishing hydrostatic Plastic strain rate solution for the safety of the body against hydrostatic fracture. In this way, the modified kinematic formulation including the limits on hydrostatic stresses are suggested for application. The modifications are also naturally added into the Plastic limit theory, which is a limiting case of the shakedown one. Also in the paper, the kinematic approach is used to deduce some simplified estimates for specific non-shakedown collapse modes of elastic Plastic structures.
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shakedown kinematic theorem for elastic perfectly Plastic Bodies
International Journal of Plasticity, 2001Co-Authors: Pham Duc ChinhAbstract:Abstract The classical shakedown kinematic theorem due to Koiter for elastic–perfectly Plastic Bodies is re-examined and divided into separated shakedown and nonshakedown theorems. While the shakedown theorem is based on the set of Koiter's Plastic strain rate cycles, the non-shakedown one involves a broader set of admissible Plastic strain rate cycles, the end-cycle accumulated strains of which are deviatoric parts of compatible strain fields. For certain broad classes of practical problems the two statements are unified to yield the unique theorem in Koiter's sense.
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Reduced forms of shakedown kinematic theorem for elastic-perfectly Plastic Bodies
Proceedings of The Royal Society A: Mathematical Physical and Engineering Sciences, 1997Co-Authors: Pham Duc ChinhAbstract:A kinematical approach, started from the structure of the loading domain, is developed for shakedown analysis of elastic‐perfectly Plastic Bodies. Reduced forms of the kinematic theorem without time integrals are deduced, which are equivalent to the primary one and reflect the path‐independent nature of shakedown capacity of the structures.
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Extended Shakedown Theorems for Elastic Plastic Bodies under Quasi-Periodic Dynamic Loading
Proceedings of The Royal Society A: Mathematical Physical and Engineering Sciences, 1992Co-Authors: Pham Duc ChinhAbstract:The shakedown theorems for elastic-perfectly Plastic Bodies subjected to quasi-periodic loads, when the amplitudes, mean values over a period and frequencies of external agencies are changing slowly with time, are presented. Examples of applications of both statical and kinematical theorems are considered.
Muneo Hori - One of the best experts on this subject based on the ideXlab platform.
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three dimensional stochastic finite element method for elasto Plastic Bodies
International Journal for Numerical Methods in Engineering, 2001Co-Authors: Maciej Anders, Muneo HoriAbstract:A new stochastic finite element method (SFEM) is formulated for three-dimensional softening elasto-Plastic Bodies with random material properties. The method is based on the Karhunen–Loeve and polynomial chaos expansions, and able to efficiently estimate complete probabilistic characteristics of the response, such as moments or PDFs. To reduce the computational complexity in the three-dimensional setting, two alterations are made with respect to the two-dimensional SFEM proposed earlier by the authors. First, a variability preserving modification of the Karhunen–Loeve expansion is rigorously derived and applied in the stochastic discretization of random fields representing material properties. Second, an efficient algorithm for parallel processing is developed, with time consumption being the same order as for an ordinary FEM, rendering the proposed SFEM an effective alternative to Monte-Carlo simulation. The applicability of the proposed method to stochastic analysis of strain localization is examined using Monte-Carlo simulation. Then, it is applied to a fault formation problem which is a recent concern of earthquake engineering. Ground surface layers are modelled by a softening elasto-Plastic body, and the evolution of probabilistic characteristics of the rupture process is analysed in detail. Some practical observations are made regarding the nature of the fault formation from the stochastic viewpoint. Copyright © 2001 John Wiley & Sons, Ltd.
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Three‐dimensional stochastic finite element method for elasto‐Plastic Bodies
International Journal for Numerical Methods in Engineering, 2001Co-Authors: Maciej Anders, Muneo HoriAbstract:A new stochastic finite element method (SFEM) is formulated for three-dimensional softening elasto-Plastic Bodies with random material properties. The method is based on the Karhunen–Loeve and polynomial chaos expansions, and able to efficiently estimate complete probabilistic characteristics of the response, such as moments or PDFs. To reduce the computational complexity in the three-dimensional setting, two alterations are made with respect to the two-dimensional SFEM proposed earlier by the authors. First, a variability preserving modification of the Karhunen–Loeve expansion is rigorously derived and applied in the stochastic discretization of random fields representing material properties. Second, an efficient algorithm for parallel processing is developed, with time consumption being the same order as for an ordinary FEM, rendering the proposed SFEM an effective alternative to Monte-Carlo simulation. The applicability of the proposed method to stochastic analysis of strain localization is examined using Monte-Carlo simulation. Then, it is applied to a fault formation problem which is a recent concern of earthquake engineering. Ground surface layers are modelled by a softening elasto-Plastic body, and the evolution of probabilistic characteristics of the rupture process is analysed in detail. Some practical observations are made regarding the nature of the fault formation from the stochastic viewpoint. Copyright © 2001 John Wiley & Sons, Ltd.
Hao Yuan - One of the best experts on this subject based on the ideXlab platform.
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local contact behavior between elastic and elastic Plastic Bodies
International Journal of Solids and Structures, 2018Co-Authors: Xiaoyun Dong, Qingming Deng, Bo Yu, Hui Wang, Panpan Weng, Chuanqing Chen, Hao YuanAbstract:Abstract The loading–unloading behavior of local contact between elastic body and elastic-ideally Plastic body is studied analytically and numerically. An analytical model is derived based on the simulating results pertinent to Brinell indentation and elastic–Plastic beam impact. The observed linear and nonlinear contact characters from simulations are introduced into the proposed analytical model. The contact law is expressed in much easier formulations by four normalized contact variables, normalized average contact pressure H ¯ , relative strain Λ, normalized contact area c2 and relative contact force Ψ. The elastic loading is following Hertz contact theory. The linear contact laws for the elastic–Plastic and fully Plastic loadings and the nonlinear contact laws for the finite deformation loading are introduced in term of the finite element (FE) contact simulations pertinent to Brinell indentation. The coefficients in the contact law are determined by fitting the FE contact simulations and by satisfying the continuous conditions. The more suitable regime of Hertz solution and a refined force–indentation relation of unloading are introduced as well into the analytical model according to the FE impact simulations. The model is finally verified with the FE simulation and experiment of elastic-ideally beam struck by elastic sphere. The analytical model shows a very good agreement between the FE-simulations and the experimental data for either low or moderate velocity impacts, while Stronge model is dependent upon impact velocity. The loading and unloading laws are highly accurate, even for the finite contact deformation in which the nearly 90% of cross section has yielded and the contact radius a (normalized by the indenter radius R) is up to a/R = 0.217.
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Local contact behavior between elastic and elastic–Plastic Bodies
International Journal of Solids and Structures, 2018Co-Authors: Xiaoyun Dong, Qingming Deng, Bo Yu, Hui Wang, Panpan Weng, Chuanqing Chen, Hao YuanAbstract:Abstract The loading–unloading behavior of local contact between elastic body and elastic-ideally Plastic body is studied analytically and numerically. An analytical model is derived based on the simulating results pertinent to Brinell indentation and elastic–Plastic beam impact. The observed linear and nonlinear contact characters from simulations are introduced into the proposed analytical model. The contact law is expressed in much easier formulations by four normalized contact variables, normalized average contact pressure H ¯ , relative strain Λ, normalized contact area c2 and relative contact force Ψ. The elastic loading is following Hertz contact theory. The linear contact laws for the elastic–Plastic and fully Plastic loadings and the nonlinear contact laws for the finite deformation loading are introduced in term of the finite element (FE) contact simulations pertinent to Brinell indentation. The coefficients in the contact law are determined by fitting the FE contact simulations and by satisfying the continuous conditions. The more suitable regime of Hertz solution and a refined force–indentation relation of unloading are introduced as well into the analytical model according to the FE impact simulations. The model is finally verified with the FE simulation and experiment of elastic-ideally beam struck by elastic sphere. The analytical model shows a very good agreement between the FE-simulations and the experimental data for either low or moderate velocity impacts, while Stronge model is dependent upon impact velocity. The loading and unloading laws are highly accurate, even for the finite contact deformation in which the nearly 90% of cross section has yielded and the contact radius a (normalized by the indenter radius R) is up to a/R = 0.217.
Maciej Anders - One of the best experts on this subject based on the ideXlab platform.
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three dimensional stochastic finite element method for elasto Plastic Bodies
International Journal for Numerical Methods in Engineering, 2001Co-Authors: Maciej Anders, Muneo HoriAbstract:A new stochastic finite element method (SFEM) is formulated for three-dimensional softening elasto-Plastic Bodies with random material properties. The method is based on the Karhunen–Loeve and polynomial chaos expansions, and able to efficiently estimate complete probabilistic characteristics of the response, such as moments or PDFs. To reduce the computational complexity in the three-dimensional setting, two alterations are made with respect to the two-dimensional SFEM proposed earlier by the authors. First, a variability preserving modification of the Karhunen–Loeve expansion is rigorously derived and applied in the stochastic discretization of random fields representing material properties. Second, an efficient algorithm for parallel processing is developed, with time consumption being the same order as for an ordinary FEM, rendering the proposed SFEM an effective alternative to Monte-Carlo simulation. The applicability of the proposed method to stochastic analysis of strain localization is examined using Monte-Carlo simulation. Then, it is applied to a fault formation problem which is a recent concern of earthquake engineering. Ground surface layers are modelled by a softening elasto-Plastic body, and the evolution of probabilistic characteristics of the rupture process is analysed in detail. Some practical observations are made regarding the nature of the fault formation from the stochastic viewpoint. Copyright © 2001 John Wiley & Sons, Ltd.
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Three‐dimensional stochastic finite element method for elasto‐Plastic Bodies
International Journal for Numerical Methods in Engineering, 2001Co-Authors: Maciej Anders, Muneo HoriAbstract:A new stochastic finite element method (SFEM) is formulated for three-dimensional softening elasto-Plastic Bodies with random material properties. The method is based on the Karhunen–Loeve and polynomial chaos expansions, and able to efficiently estimate complete probabilistic characteristics of the response, such as moments or PDFs. To reduce the computational complexity in the three-dimensional setting, two alterations are made with respect to the two-dimensional SFEM proposed earlier by the authors. First, a variability preserving modification of the Karhunen–Loeve expansion is rigorously derived and applied in the stochastic discretization of random fields representing material properties. Second, an efficient algorithm for parallel processing is developed, with time consumption being the same order as for an ordinary FEM, rendering the proposed SFEM an effective alternative to Monte-Carlo simulation. The applicability of the proposed method to stochastic analysis of strain localization is examined using Monte-Carlo simulation. Then, it is applied to a fault formation problem which is a recent concern of earthquake engineering. Ground surface layers are modelled by a softening elasto-Plastic body, and the evolution of probabilistic characteristics of the rupture process is analysed in detail. Some practical observations are made regarding the nature of the fault formation from the stochastic viewpoint. Copyright © 2001 John Wiley & Sons, Ltd.