检索结果-内蒙古大学图书馆

A robust stress update algorithm for elastoplastic models without analytical derivation of the consistent tangent operator and loading/unloading estimation

引用

INTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS 2023年第6期47卷 1022-1050页

作者： Lu, Dechun Zhang, Yaning Zhou, Xin Su, Cancan Gao, Zhiwei Du, Xiuli Beijing Univ Technol Inst Geotech & Underground Engn Beijing Peoples R China Univ Glasgow James Watt Sch Engn Glasgow City Scotland Beijing Univ Technol Inst Geotech & Underground Engn Beijing 100124 Peoples R China

A robust and concise implicit stress integration algorithm of elastoplastic models is presented. It does not require the loading/unloading estimation and analytical derivation operation for the stress update. First, the elastoplastic stress update problem is recast into an unconstrained minimization problem by utilizing the smooth function to bypass the loading/unloading estimation. Then, the object problem is solved by the line search method instead of the Newton method for better convergence. The consistent tangent operator is evaluated by the complex step derivative approximation without the subtraction cancellation error, which provides the quadratic convergence rate of global iteration. The rationality of the numerical consistent tangent operator is validated by the one obtained by the analytical derivation. A recently developed non-orthogonal elastoplastic (NEP) clay model is implemented using the new algorithm. The algorithm is confirmed through comparing the numerical solution and the analytical one for a cavity expansion problem. The algorithm performance is assessed based on a series of geotechnical boundary value problems. It is found that the new algorithm is more robust than the one employed by ABAQUS. The source code of the model implementation can be downloaded from .

关键词： complex step derivative approximation consistent tangent operator constitutive model line search method smooth function stress update algorithm

来源：评论

学校读者我要写书评

暂无评论

stress update algorithm for enhanced homogeneous anisotropic hardening model

引用

COMPUTER METHODS IN APPLIED MECHANICS AND ENGINEERING 2015年 286卷 63-86页

作者： Lee, J. Kim, D. Lee, Y. -S. Bong, H. J. Barlat, F. Lee, M. -G. Korea Inst Mat Sci Mat Deformat Dept Chang Won 642831 South Korea Pohang Univ Sci & Technol Grad Inst Ferrous Technol Pohang 790784 South Korea Korea Univ Dept Mat Sci & Engn Seoul 136713 South Korea

A stress integration algorithm is provided for a novel homogeneous-yield-function-based anisotropic hardening (HAH) model. The new model is an extension of the original HAH model that describes cross-hardening or softening of a sheet metal under an orthogonal strain path change. A semi-explicit integration scheme for the stress update is utilized to efficiently handle the gradient of the distorted yield surface during complex strain path changes, as originally proposed by Lee et al. (2012). Validations of the algorithm developed were conducted by comparing the predicted stress-strain curves of dual-phase (DP) 780 and extra-deep-drawing-quality (EDDQ) steels with experimental stress-strain responses observed under cross-loading conditions. Finally, the accuracy of the proposed finite element (FE) formulations was assessed by r-value prediction and preparation of iso-error maps. (C) 2014 Elsevier B.V. All rights reserved.

关键词： Anisotropic hardening stress update algorithm Cross-loading Yield surface

来源：评论

学校读者我要写书评

暂无评论

Distortional hardening revisited: Advanced strength prediction model after multi-directional forming

引用

INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES 2025年 286卷

作者： Choi, Seonghwan Kim, Seungwoo Kang, Soo-Chang Lee, Myoung-Gyu Seoul Natl Univ Dept Mat Sci & Engn Seoul 08826 South Korea Seoul Natl Univ RIAM Seoul 08826 South Korea POSCO Steel Solut Res Lab 180-1 Songdo Dong Incheon 21985 South Korea

This study presents the first in-depth evaluation of the Extended Homogeneous Anisotropic Hardening (HEXAH) model for industrial-scale applications, particularly in multi-axial pipe forming processes. Building upon the Homogeneous Anisotropic Hardening (HAH) models, the HEXAH model addresses the limitations of HAH models, including "rotation singularity", by incorporating multiple microstructure deviators to resolve physical discrepancies. This enhancement enables more reliable modeling of material response under cross-loading conditions. The HEXAH model was implemented into finite element (FE) analysis through a novel fully implicit stress update algorithm within ABAQUS, utilizing a user material subroutine (UMAT)-the HEXAH-FE framework. A comparative analysis was conducted in an industrial context, predicting the mechanical strength of the steel plate after multi-directional pipe forming processes. As a main result, only the HEXAH model accurately predicted yield strength along the hoop direction (HD), especially under cross-loading conditions where other HAH models fell short. The HEXAH model's ability to allow superposed distortions highlights its superiority in representing anisotropic hardening even under complex loading conditions. This study introduces the first application and validation of the HEXAH framework to real-world, industrial-scale problems with its implementation. Our work bridges the gap between theoretical advancements in material modeling and practical industrial applications.

关键词： Anisotropic hardening Finite element analysis Mechanical strength Pipe forming process Distortional hardening stress update algorithm

来源：评论

学校读者我要写书评

暂无评论

An efficient nonlocal integral method based on the octree algorithm

引用

COMPUTERS AND GEOTECHNICS 2024年 176卷

作者： Lu, Dechun Zhang, Yaning Zhou, Xin Meng, Fanping Su, Cancan Du, Xiuli Beijing Univ Technol Inst Geotech & Underground Engn Beijing 100124 Peoples R China Tsinghua Univ Minist Educ Key Lab Civil Engn Safety & Durabil Beijing 100084 Peoples R China Leibniz Univ Hannover Inst Photon Dept Math & Phys D-30060 Hannover Germany

The nonlocal integral method typically requires a very high computing cost to search neighborhood integration points for calculating the nonlocal variable, which limits its application in large-scale problems. This paper proposes an efficient nonlocal integral method based on the octree algorithm, in which the integration point information is stored in the tree data structure to accelerate the search task. Firstly, the fundamental principles and implementation details of using the octree algorithm to search neighborhood integration points are described in detail. Subsequently, a Mohr-Coulomb nonlocal damage plastic model is presented as the application object of the proposed method. The model is implemented further in the ABAQUS using the octree-based nonlocal method and the return mapping algorithm enhanced by a line search method. Finally, two typical boundary value problems are simulated to verify the effectiveness and to assess the computational efficiency of the proposed nonlocal method. For the given test environment, the octree algorithm can achieve up to 100 times speedup at the integration point level compared to the traversal algorithm, and the developed efficient nonlocal method can achieve up to 7.9 times speedup at the boundary value problem level compared to the original nonlocal method.

关键词： Nonlocal integral method Octree algorithm Strain softening model stress update algorithm

来源：评论

学校读者我要写书评

暂无评论

A return mapping algorithm based on the hyper dual step derivative approximation for elastoplastic models

引用

COMPUTER METHODS IN APPLIED MECHANICS AND ENGINEERING 2023年第PartA期417卷

作者： Zhou, Xin Shi, Anyu Lu, Dechun Chen, Yun Zhuang, Xiaoying Lu, Xinzheng Du, Xiuli Beijing Univ Technol Inst Geotech & Underground Engn Beijing 100124 Peoples R China Tsinghua Univ Dept Civil Engn Beijing 100084 Peoples R China Leibniz Univ Hannover Inst Continuum Mech D-30060 Hannover Germany

Accurately evaluating derivatives poses a key challenge when numerically implementing complex constitutive models. This work presents an implicit stress update algorithm that utilizes the hyper dual step derivative approximation to address derivative evaluations in elastoplastic problems. Initially, the performance of various numerical differentiation methods is discussed and compared by examining their numerical errors in the representative example. Subsequently, the hyper dual step derivative approximation, without truncation and subtractive cancellation errors, is employed to compute the Jacobian matrix and consistent tangent operator, ensuring quadratic convergence in both local and global computations. The size of the Newton search step is optimized by the line search technique, thereby enhancing the convergence in solving nonlinear stress integral equations. Finally, the proposed stress update algorithm is used to implement the non-associated Mohr-Coulomb plastic model in the ABAQUS software using the UMAT subroutine. The stress update algorithm's performance and its practical application in geotechnical engineering problems are demonstrated using five boundary value problems. (c) 2023 Elsevier B.V. All rights reserved.

关键词： stress update algorithm Plastic model Hyper dual step approximation Line search method Consistent tangent operator

来源：评论

学校读者我要写书评

暂无评论

A non-associated flow rule with simple non-branching form representing the apparent non-normality effects after abrupt strain-path change

引用

INTERNATIONAL JOURNAL OF PLASTICITY 2022年 159卷

作者： Zhang, Tianyin Liu, Maosheng Han, Xianhong Shanghai Jiao Tong Univ Natl Engn Res Ctr Die & Mold CAD Shanghai 200240 Peoples R China Shanghai Jiao Tong Univ State Key Lab Met Matrix Composites Shanghai 200240 Peoples R China Shanghai Jiao Tong Univ Inst Forming Technol & Equipment Sch Mat Sci & Engn Shanghai 200030 Peoples R China Baosteel Engn & Technol Grp Co LTD Shanghai 201999 Peoples R China

Although the existed 'corner models' are capable of reasonably predicting experimental obser-vations of the corner effects including the formation of a sharp vertex on the subsequent yield surface and the apparent non-normality of plastic flows after abrupt strain-path change, these models have not been widely used in metal forming computation due to their complexity. The present work proposes a non-associated flow rule with simple non-branching form to represent the non-normality effects after abrupt strain-path change. Then a stable stress update algorithm for the present rule is developed, based on the fully implicit backward Euler method. The present rule is implemented in ABAQUS and its effectiveness is verified through the FEM simulations of two typical strain-path change experiments. Furthermore, some concerned influencing factors of the non-normality effects after strain-path change are discussed. The results show that the new rule has good prediction performance by comparing with the previous works by Simo, Yoshida et al. and the associated flow rule (AFR). And the combination of the non-associated flow rule and the visco-plastic model can closely reproduce the complete experimental observations of corner effects. Moreover, the plane strain tension simulations reveal that the proposed rule predicts the earlier and sharper strain localization than AFR.

关键词： Non-associated flow rule Non-normality Strain-path change stress update algorithm

来源：评论

学校读者我要写书评

暂无评论

Numerical integration algorithm of updated homogeneous anisotropic hardening model through finite element framework

引用

COMPUTER METHODS IN APPLIED MECHANICS AND ENGINEERING 2020年 372卷 113449-113449页

作者： Yoon, Seong-Yong Lee, Shin-Yeong Barlat, Frederic Pohang Univ Sci & Technol Grad Inst Ferrous Technol 77 Cheongam Ro Pohang 37673 Gyeongbuk South Korea

In this work, an updated version of the homogeneous anisotropic hardening (HAH20) model proposed by Barlat et al. (2020) is implemented into a finite element framework through a stress integration algorithm. To improve the convergence of this model inside the integration algorithm, the algorithmic step sizes of the solution variable increments are controlled by the line-search method. The HAH20 implementation is validated by comparing the simulation results obtained from the finite element analysis with those calculated by stand-alone HAH20 code. In addition, the simulation results of tests, including strain path changes such as tension-compression and cross-loading, are compared with experimental measurements, and the effectiveness of the step size control in the current HAH20 model is investigated. The performance of the implemented algorithm is analyzed through convergence maps for critical strain path change simulations. (C) 2020 Elsevier B.V. All rights reserved.

关键词： Anisotropic yield function Anisotropic hardening model Finite element method Computational plasticity stress update algorithm

来源：评论

学校读者我要写书评

暂无评论

Explicit, fully implicit and forward gradient numerical integration of a hyperelasto-viscoplastic constitutive model for amorphous polymers undergoing finite deformation

引用

COMPUTATIONAL MECHANICS 2019年第5期64卷 1389-1401页

作者： Bonnaud, Etienne L. Faleskog, Jonas Royal Inst Technol Dept Solid Mech S-10044 Stockholm Sweden

Following the growing use of amorphous polymers in an expanding range of applications, interest for numerical modeling of polymer behavior has greatly increased. Together with reliable constitutive models, stable, accurate and rapid integration algorithms valid for large deformations need to be developed. Here, in the framework of hyperelasto-viscoplasticity and multiplicative split formulation, three integration algorithms (explicit, fully implicit and forward gradient) are generated for a constitutive polymer model and respective stability is investigated. The algorithms are furthermore implemented in a commercial Finite Element code and simulation of a full field tensile test is shown to capture the actual deformation behavior of polymers.

关键词： Amorphous polymers Viscoplasticity Finite element method stress update algorithm Finite strain

来源：评论

学校读者我要写书评

暂无评论

An SBFEM Approach for Rate-Dependent Inelasticity with Application to Image-Based Analysis

引用

INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES 2020年 182卷 105778-105778页

作者： Eisentrager, Johanna Zhang, Junqi Song, Chongmin Eisentrager, Sascha Univ New South Wales Sch Civil & Environm Engn Sydney NSW Australia

The contribution at hand presents the implementation of a non-linear constitutive model for rate-dependent inelasticity into the scaled boundary finite element method (SBFEM). To increase the numerical efficiency and simplify the formulation, the stress update algorithm is only performed at the scaling centre of the polytope elements. The presented SBFEM framework is ideally suited for the image-based analysis of composites since many matrix materials exhibit rate-dependent inelasticity, particularly at high temperatures. Thereby, meshes are generated based on images of the complex microstructures by employing an efficient quadtree-decomposition. The main advantage of this approach lies in its high degree of automation requiring only minimal intervention by the user. Various benchmark examples are presented to verify the formulation. Furthermore, the influence of jagged boundaries, resulting from the quadtree decomposition, on the accuracy and convergence of results is discussed in detail. The paper concludes with the study of a metal-matrix composite, whereby rate-dependent inelasticity is taken into account to model the mechanical behaviour of the matrix.

关键词： Scaled boundary finite element method Rate-dependent inelasticity stress update algorithm Image-based analysis Quadtree algorithm

来源：评论

学校读者我要写书评

暂无评论

Simulation of the irradiation-induced thermo-mechanical behaviors evolution in monolithic U-Mo/Zr fuel plates under a heterogeneous irradiation condition

引用

NUCLEAR ENGINEERING AND DESIGN 2015年 285卷 84-97页

作者： Zhao, Yunmei Gong, Xin Ding, Shurong Fudan Univ Dept Mech & Engn Sci Shanghai 200433 Peoples R China

For monolithic fuel plates with U-Mo foil and Zircalloy cladding, the three-dimensional large deformation incremental constitutive relations and stress update algorithms in the co-rotational coordinate framework are developed for the fuel and cladding with their respective irradiation effects involved. Three-dimensional finite element simulation of their in-pile thermo-mechanical coupling behaviors under a location-dependent irradiation condition is implemented via the validated user-defined subroutines UMATHT and UMAT in ABAQUS. Comparison of the simulation results for two cases with or without creep considered in the U-Mo foil indicates that with the irradiation creep included (1) considerable stress-relaxation appears in the U-Mo foil, and the mechanical interaction between fuel and cladding is weakened;(2) approximately identical thickness increments in the plate and fuel foil exist and become comparably larger;(3) plastic deformation in the cladding is significantly diminished. (C) 2015 Elsevier B.V. All rights reserved.

关键词： Monolithic plate Irradiation swelling and creep Irradiation growth stress update algorithm Co-rotational coordinate system

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：