A NONLINEAR MATERIAL MODEL OF CORRODED REBARS FOR SEISMIC RESPONSE OF BRIDGES

Engineering test data occasionally violate assumptions underlying standard material model identification. Consequently, one has to apply appropriate remedies with respect to each violation to enhance the reliability of identified material parameters. This paper generalizes the use of the signal-to-noise weighting scheme when heteroscedasticity of test data are suspected. Different mathematical and practical aspects of the approach are discussed. Additionally, the ensuing weighted identification process is simplified to an equivalent standard form by means of a space transformation. Finally, the approach is applied to the identification of a nonlinear material model for textile composites, on both qualitative and quantitative levels.

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A Finite-Element and Experimental Analysis of Stress Distribution in Various Shear Tests for Solder Joints

Journal of Electronic Packaging ◽

10.1115/1.2792277 ◽

1998 ◽

Vol 120 (1) ◽

pp. 106-113 ◽

Cited By ~ 26

Author(s):

T. Reinikainen ◽

M. Poech ◽

M. Krumm ◽

J. Kivilahti

Keyword(s):

Finite Element ◽

Stress Distribution ◽

Low Cycle Fatigue ◽

Material Model ◽

Lap Joints ◽

Optical Measurements ◽

Nonlinear Material ◽

Lap Joint ◽

The Finite Element Method ◽

Shear Tests

Solder alloys are commonly tested with shear tests to study their mechanical properties or low-cycle fatigue performance. In this work, the suitability of various shear tests for quantitative solder-joint testing is investigated by means of the finite element method. The stress state and stress distribution in the following well known geometries are studied: the double-lap test, the ring and plug test, the losipescu test, and two single-lap tests. A new test geometry, the grooved-lap test, is introduced and compared to the conventional tests. The results of simulations with an elastic material model in plane-strain indicate that considerable differences in the purity of the state of shear (rε = −ε1/ε3) as well as in the stress distribution in the joint exist among the shear tests. However, simulations with a nonlinear material model show that stress inhomogenities are smoothed by the plastic and creep deformation occurring in the joint. Optical measurements of the deformation of real single-lap and grooved-lap joints show that the single-lap joint rotates slightly during creep, whereas in the grooved-lap joint no rotation can be detected. This confirms the simulation results that in the single-lap test the initially nonuniform stress distribution changes during creep, and in the grooved-lap test the uniform stress distribution remains constant through the test.

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Nonlinear Material Model in Part Variation Simulations of Sheet Metals

Journal of Computing and Information Science in Engineering ◽

10.1115/1.4042539 ◽

2019 ◽

Vol 19 (2) ◽

Cited By ~ 2

Author(s):

Soner Camuz ◽

Samuel Lorin ◽

Kristina Wärmefjord ◽

Rikard Söderberg

Keyword(s):

Material Model ◽

Nonlinear Material ◽

Isotropic Hardening ◽

Elastoplastic Material ◽

Processing Unit ◽

Central Processing ◽

Physical Experiments ◽

Linear Relationships ◽

Influence Coefficients ◽

Variation Simulation

Current methodologies for variation simulation of compliant sheet metal assemblies and parts are simplified by assuming linear relationships. From the observed physical experiments, it is evident that plastic strains are a source of error that is not captured in the conventional variational simulation methods. This paper presents an adaptation toward an elastoplastic material model with isotropic hardening in the method of influence coefficients (MIC) methodology for variation simulations. The results are presented in two case studies using a benchmark case involving a two-dimensional (2D) quarter symmetric plate with a centered hole, subjected to both uniaxial and biaxial displacement. The adaptation shows a great reduction in central processing unit time with limited effect on the accuracy of the results compared to direct Monte Carlo simulations.

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Experiment and Elastic-Plastic Modelling of the IPN160 Beam

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.769.331 ◽

2015 ◽

Vol 769 ◽

pp. 331-335

Author(s):

Jakub Vasek ◽

Oldrich Sucharda

Keyword(s):

Computational Models ◽

Plastic Material ◽

Numerical Models ◽

Steel Structure ◽

Material Model ◽

Nonlinear Material ◽

Software Application ◽

Elastic Plastic ◽

Elastic Plastic Material ◽

Isoparametric Finite Elements

The paper compares the numerical models of and experiments with a beam. The purpose is to evaluate the nonlinear material model of a steel structure. The steel is modelled as an ideal elastic-plastic material. The FEM and eight-node isoparametric finite elements are considered in the analysis. The 3D calculations use different material constants and several approaches are being tested in order to create the computational models. The calculations are performed in the software application developed by our university.

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Nonlinear Behaviour of Concrete Foundation Slab

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.821.495 ◽

2016 ◽

Vol 821 ◽

pp. 495-502

Author(s):

Josef Fiedler ◽

Tomáš Koudelka

Keyword(s):

Finite Element Method ◽

Concrete Slab ◽

Material Model ◽

Nonlinear Material ◽

Nonlinear Behaviour ◽

Plastic Yielding ◽

The Finite Element Method ◽

Foundation Slab ◽

Subsoil Model ◽

Concrete Computation

A layered model is used for nonlinear analysis of a foundation concrete slab. Calculation is performed using interaction with elastic Winkler-Pasternak subsoil model and considering plastic yielding of slab layers. Two Drucker-Prager yield criterions define a nonlinear material model for concrete. Computation is done by the SIFEL solver using the Finite Element Method.

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Buckling of Rectangular Cross-Ply Laminated Plates With Nonlinear Stress-Strain Behavior

Journal of Applied Mechanics ◽

10.1115/1.3424619 ◽

1979 ◽

Vol 46 (3) ◽

pp. 637-643 ◽

Cited By ~ 8

Author(s):

Harold S. Morgan ◽

Robert M. Jones

Keyword(s):

Strain Curve ◽

Material Model ◽

Laminated Plates ◽

Nonlinear Material ◽

Stress Strain ◽

Buckling Loads ◽

Strain Behavior ◽

Reinforced Composite ◽

Nonlinear Stress ◽

Behavior Characteristic

The Jones-Nelson-Morgan nonlinear material model is used in the derivation of a buckling criterion for laminated plates with nonlinear stress-strain behavior characteristic of many fiber-reinforced composite materials. A search procedure is developed to solve this buckling criterion which is transcendental because of interdependence of the buckling load and the coefficients relating the variations in laminate forces and moments to the variations in strains and curvatures. The effect of stress-strain curve nonlinearities on laminate buckling loads is illustrated by comparing solutions of the buckling criterion to buckling loads for laminates with linear stress-strain behavior.

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Elastography Method for Reconstruction of Nonlinear Breast Tissue Properties

International Journal of Biomedical Imaging ◽

10.1155/2009/406854 ◽

2009 ◽

Vol 2009 ◽

pp. 1-9 ◽

Cited By ~ 16

Author(s):

Z. G. Wang ◽

Y. Liu ◽

G. Wang ◽

L. Z. Sun

Keyword(s):

Breast Tissue ◽

Three Dimensional ◽

Material Model ◽

Nonlinear Material ◽

Fatty Tissue ◽

Nonlinear Method ◽

Tissue Properties ◽

Breast Cancer Study ◽

Breast Phantom ◽

The Difference

Elastography is developed as a quantitative approach to imaging linear elastic properties of tissues to detect suspicious tumors. In this paper a nonlinear elastography method is introduced for reconstruction of complex breast tissue properties. The elastic parameters are estimated by optimally minimizing the difference between the computed forces and experimental measures. A nonlinear adjoint method is derived to calculate the gradient of the objective function, which significantly enhances the numerical efficiency and stability. Simulations are conducted on a three-dimensional heterogeneous breast phantom extracting from real imaging including fatty tissue, glandular tissue, and tumors. An exponential-form of nonlinear material model is applied. The effect of noise is taken into account. Results demonstrate that the proposed nonlinear method opens the door toward nonlinear elastography and provides guidelines for future development and clinical application in breast cancer study.

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Nonlinear Material Model for Quasi-Unidirectional Woven Composite Accounting for Viscoelastic, Viscous Deformation, and Stiffness Reduction

Polymers ◽

10.3390/polym10080903 ◽

2018 ◽

Vol 10 (8) ◽

pp. 903 ◽

Cited By ~ 1

Author(s):

Zhanyu Zhai ◽

Bingyan Jiang ◽

Dietmar Drummer

Keyword(s):

Material Model ◽

Tensile Tests ◽

Experimental Results ◽

Nonlinear Material ◽

Weibull Function ◽

Viscous Deformation ◽

Stiffness Reduction ◽

Viscoelastic Strain ◽

Proposed Model ◽

The Individual

To clarify the individual contribution of viscoelastic and viscous deformation to the global nonlinear response of composites, multilevel cyclic loading-unloading recovery tensile tests were carried out. The experimental results show that there is a linear relationship between the viscous strain and viscoelastic strain of composites, regardless of the off-axis angle or loading stress level. On the basis of experimental results, a coupled damage-plasticity constitutive model was proposed. In this model, the plasticity theory was adopted to assess the evolution of viscous strains. The viscoelastic strain was represented as a linear function of viscous strains. Moreover, the Weibull function of the effective stress was introduced to evaluate the damage variables in terms of stiffness reduction. The tensile stress-strain curves, predicted by the proposed model, showed a good agreement with experimental results.

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11.23: Influence of the uniaxial material model of steel on the seismic response of steel structures

ce/papers ◽

10.1002/cepa.353 ◽

2017 ◽

Vol 1 (2-3) ◽

pp. 3013-3022 ◽

Cited By ~ 2

Author(s):

Melina Bosco ◽

Aurelio Ghersi ◽

Edoardo M. Marino ◽

Pier Paolo Rossi

Keyword(s):

Seismic Response ◽

Steel Structures ◽

Material Model

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Slotted Beam-Column Energy Dissipating Connections: Applicability and Seismic Behavior

Advances in Civil Engineering ◽

10.1155/2021/5530083 ◽

2021 ◽

Vol 2021 ◽

pp. 1-16

Author(s):

Xin Zhao ◽

Ai Qi

Keyword(s):

Energy Dissipation ◽

Seismic Response ◽

Cross Sections ◽

Material Model ◽

Reduction Ratio ◽

Frame Structure ◽

Variable Cross ◽

Good Energy ◽

Prefabricated Structure ◽

Controlled Structure

Energy dissipating joint can effectively strengthen the connection of prefabricated buildings. In the present study, a new slotted mild steel damper was installed at the beam end of the prefabricated structure to form as the energy-dissipating joint of the beam-column. By using ABAQUS software, a finite element (FE) analysis was conducted for the single-story-and-span of the single-frame structure with a slotted damper as energy-dissipating joint. The result shows that the damper was the first to yield in the structure and performed well in energy dissipation, indicating its reasonable design of structure and connection. The energy dissipation mainly occurred at the flange of the variable cross sections, between which beam-ribbed webs ensured the required bearing capacity and stiffness and provided a reliable connection. The hysteretic curves were obtained by analyzing the mechanical properties of the slotted damper under pure bending and pure shearing. In the OpenSees platform, the Steel02 Material model and the twoNodeLink element were used to fit the hysteretic curves; this method was employed for the parametric simulation of the slotted energy dissipation. The dynamic characteristics and seismic response of the controlled structure with slotted energy dissipating joint were also analyzed and compared with those of the uncontrolled structure in the OpenSees platform. The results show that the period of the controlled structure was prolonged and the top story acceleration decreased, indicating its effect in reducing seismic response. The shear-dependent seismic reduction ratio was about 35%, while the drift-dependent seismic reduction ratio was about 10%. The seismic performance of bottom story was better than that of the top story, and the damper has good energy dissipation performance in the bending direction. Some detailed design criteria are put forward and consequences for design on the basis of the performed simulations are shown.

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