Yield Surface Investigation of Alloys During Model Disk Spin Tests

2014 ◽  
Author(s):  
Anton N. Servetnik ◽  
Evgeny P. Kuzmin
Keyword(s):  
Experimental Approach ◽  
Eddy Currents ◽  
Material Model ◽  
Isotropic Hardening ◽  
Model Parameters ◽  
Element Analysis ◽  
Strain Fields ◽  
Von Mises ◽  
Yield Conditions ◽  
Incremental Theory Of Plasticity

Results of quasi-static numerical simulation of spin tests of model disk made from high-temperature forged alloy are presented. To determine stress-strain state of disk during loading finite element analysis is used. Simulation of elastic-plastic strain fields was carried out using incremental theory of plasticity with isotropic hardening. Model sensitivity from Von mises and Tresca yield conditions and hardening conditions was investigated. To identify the material model parameters an experimental approach of rim radial displacement measurement by eddy currents sensor during the load-unload of spin test was used. Calculation made using different material models were compared with the experimental results.

Elasto-Plastic Impact: Non-Linear FEA vs. Experimental Results

1999 ◽  
Author(s):  
Todd C. Werner ◽  
Daniel H. Suchora
Keyword(s):  
Initial Velocity ◽  
Material Model ◽  
Isotropic Hardening ◽  
Analysis Software ◽  
Element Analysis ◽  
Event Simulation ◽  
Linear Finite Element ◽  
Non Linear ◽  
Von Mises ◽  
The Impact

Abstract This paper analyzes the problem of a weight with a specified initial velocity impacting the end of an aluminum cantilever beam. The impact is severe enough to cause significant plastic bending strains in the beam. The impact is modeled using the Algor Event Simulation Non-linear Finite Element Analysis software using 21 node brick elements and a Von-Mises material model with isotropic hardening. Raleigh damping is included in the simulation. The computer generated strain vs. time results are compared to traces obtained from a strain gage instrumented beam subjected to the impact modeled by the software. The comparison of the non-linear FEA computer results and the experimental data shows good correlation.

The Precise Determination of the Johnson–Cook Material and Damage Model Parameters and Mechanical Properties of an Aluminum 7068-T651 Alloy

2019 ◽  
Vol 141 (4) ◽  
Author(s):  
B. Bal ◽  
K. K. Karaveli ◽  
B. Cetin ◽  
B. Gumus
Keyword(s):  
Mechanical Properties ◽  
Strain Rate ◽  
Physical Simulation ◽  
Damage Model ◽  
Rolling Direction ◽  
Stress Triaxiality ◽  
Material Model ◽  
Tensile Tests ◽  
Model Parameters ◽  
Element Analysis

Al 7068-T651 alloy is one of the recently developed materials used mostly in the defense industry due to its high strength, toughness, and low weight compared to steels. The aim of this study is to identify the Johnson–Cook (J–C) material model parameters, the accurate Johnson–Cook (J–C) damage parameters, D1, D2, and D3 of the Al 7068-T651 alloy for finite element analysis-based simulation techniques, together with other damage parameters, D4 and D5. In order to determine D1, D2, and D3, tensile tests were conducted on notched and smooth specimens at medium strain rate, 100 s−1, and tests were repeated seven times to ensure the consistency of the results both in the rolling direction and perpendicular to the rolling direction. To determine D4 and D5 further, tensile tests were conducted on specimens at high strain rate (102 s−1) and temperature (300 °C) by means of the Gleeble thermal–mechanical physical simulation system. The final areas of fractured specimens were calculated through optical microscopy. The effects of stress triaxiality factor, rolling direction, strain rate, and temperature on the mechanical properties of the Al 7068-T651 alloy were also investigated. Damage parameters were calculated via the Levenberg–Marquardt optimization method. From all the aforementioned experimental work, J–C material model parameters were determined. In this article, J–C damage model constants, based on maximum and minimum equivalent strain values, were also reported which can be utilized for the simulation of different applications.

scholarly journals A Material Model for Pipeline Steels

1996 ◽  
Author(s):  
James D. Hart ◽  
Graham H. Powell ◽  
Nasir Zulfiqar
Keyword(s):  
Material Model ◽  
Deformation Analysis ◽  
Model Parameters ◽  
Pipeline System ◽  
Test Results ◽  
Strain Data ◽  
Safety Assessments ◽  
Stress And Deformation ◽  
Pressurized Pipelines ◽  
Von Mises

Experience has shown that the pipe steel used in the Trans-Alaska Pipeline System has complex properties that must be taken into account in making safety assessments of the pipe. To obtain a better understanding of the steel behavior, a detailed test program has recently been undertaken. The test results have been used to develop a nonlinear model of the steel for use in stress and deformation analysis of the pipeline. This paper first outlines the model, and shows that it captures important aspects of the steel behavior, including progressive yielding and anisotropy. The paper then shows how the values of the model parameters can be calculated from experimental stress-strain data, and how the model can be used for the analysis of pressurized pipelines, accounting for interaction between hoop and longitudinal stress. The theory is based on von Mises yield and the Mroz plasticity model.

Modeling of Crack Propagation in Defective X100 Line Pipes

2020 ◽  
Author(s):  
Lufeng Xue ◽  
Marcelo Paredes ◽  
Aida Nonn ◽  
Tomasz Wierzbicki
Keyword(s):  
Crack Propagation ◽  
Fracture Initiation ◽  
Material Model ◽  
Ring Expansion ◽  
Yield Function ◽  
Experimental Program ◽  
Isotropic Hardening ◽  
Model Parameters ◽  
Expansion Test ◽  
Initiation And Propagation

Abstract A comprehensive experimental program is carried out to determine material parameters for fracture initiation and propagation in X100 pipeline steels. The quadratic Hill’48 yield function along with an isotropic hardening are used to describe plastic flow at large deformation and a phenomenological fracture criterion to predict fracture initiation. Fracture mechanics SENT specimens are used to calibrate post-initiation softening parameters necessary for ductile crack propagation in thick components. Once the material model parameters set is complete a final comparison is conducted with ring expansion test on same material.

scholarly journals BAYESIAN INFERENCE OF HETEROGENEOUS VISCOPLASTIC MATERIAL PARAMETERS

2018 ◽  
Vol 15 ◽  
pp. 41-45
Author(s):  
Eliška Janouchová ◽  
Anna Kučerová
Keyword(s):  
Experimental Data ◽  
Bayesian Inference ◽  
Material Model ◽  
Isotropic Hardening ◽  
Model Parameters ◽  
Viscoplastic Material ◽  
Loading Test ◽  
Model Response ◽  
Probabilistic Description ◽  
Probabilistic Setting

<p>Modelling of heterogeneous materials based on randomness of model input parameters involves parameter identification which is focused on solving a stochastic inversion problem. It can be formulated as a search for probabilistic description of model parameters providing the distribution of the model response corresponding to the distribution of the observed data</p><p>In this contribution, a numerical model of kinematic and isotropic hardening for viscoplastic material is calibrated on a basis of experimental data from a cyclic loading test at a high temperature. Five material model parameters are identified in probabilistic setting. The core of the identification method is the Bayesian inference of uncertain statistical moments of a prescribed joint lognormal distribution of the parameters. At first, synthetic experimental data are used to verify the identification procedure, then the real experimental data are processed to calibrate the material model of copper alloy.</p>

Additional Guidance for Inelastic Ratcheting Analysis Using the Chaboche Model

2014 ◽  
Author(s):  
William F. Weitze ◽  
Timothy D. Gilman
Keyword(s):  
Finite Element Analysis ◽  
Stainless Steel ◽  
Cylindrical Shell ◽  
Kinematic Hardening ◽  
Material Model ◽  
Model Parameters ◽  
Temperature Dependent ◽  
Model Refinement ◽  
Element Analysis ◽  
Chaboche Model

This paper builds on PVP2013-98150 by Kalnins, Rudolph, and Willuweit [1], which documented two calibration processes for determining the parameters of the Chaboche nonlinear kinematic hardening (NLK) material model for stainless steel, and tested the material model using a pressurized cylindrical shell subjected to thermal cycling. The current paper examines (1) whether a Chaboche NLK model with only two terms (rather than four as in PVP-98150) is sufficiently accurate, (2) use of the ANSYS program for material model refinement and finite element analysis, and (3) analysis using temperature-dependent NLK model parameters, again using ANSYS.

A Transversely Isotropic Viscoelastic Constitutive Equation for Brainstem Undergoing Finite Deformation

2006 ◽  
Vol 128 (6) ◽  
pp. 925-933 ◽  
Author(s):  
Xinguo Ning ◽  
Qiliang Zhu ◽  
Yoram Lanir ◽  
Susan S. Margulies
Keyword(s):  
Shear Deformation ◽  
Transversely Isotropic ◽  
Material Model ◽  
Model Parameters ◽  
Shear Stresses ◽  
Element Analysis ◽  
Cross Sectional ◽  
Implementation Model ◽  
Finite Shear ◽  
The Matrix

The objective of this study was to define the constitutive response of brainstem undergoing finite shear deformation. Brainstem was characterized as a transversely isotropic viscoelastic material and the material model was formulated for numerical implementation. Model parameters were fit to shear data obtained in porcine brainstem specimens undergoing finite shear deformation in three directions: parallel, perpendicular, and cross sectional to axonal fiber orientation and determined using a combined approach of finite element analysis (FEA) and a genetic algorithm (GA) optimizing method. The average initial shear modulus of brainstem matrix of 4-week old pigs was 12.7Pa, and therefore the brainstem offers little resistance to large shear deformations in the parallel or perpendicular directions, due to the dominant contribution of the matrix in these directions. The fiber reinforcement stiffness was 121.2Pa, indicating that brainstem is anisotropic and that axonal fibers have an important role in the cross-sectional direction. The first two leading relative shear relaxation moduli were 0.8973 and 0.0741, respectively, with corresponding characteristic times of 0.0047 and 1.4538s, respectively, implying rapid relaxation of shear stresses. The developed material model and parameter estimation technique are likely to find broad applications in neural and orthopaedic tissues.

Nonlinear Analysis of Bioprosthetic Heart Valves under Dynamic Loading

2012 ◽  
Vol 152-154 ◽  
pp. 732-736
Author(s):  
Quan Yuan ◽  
Xin Ye ◽  
Hai Bo Ma ◽  
Hua Cong ◽  
Xu Huang
Keyword(s):  
Heart Valve ◽  
Heart Valves ◽  
Material Model ◽  
Von Mises Stress ◽  
Stress Distributions ◽  
Bioprosthetic Heart Valve ◽  
Element Analysis ◽  
Bioprosthetic Heart Valves ◽  
Diastolic Phase ◽  
Von Mises

In order to investigate the effect of material nonlinearity on the dynamic behavior of bioprosthetic heart valve, we establish the spherical, cylindrical and ellipsoidal leaflets models with the material model of Mooney-Rivlin. The mechanical behavior of bioprosthetic valve leaflet during diastolic phase is analyzed. The finite element analysis results show that the stress distributions of the ellipsoidal and spherical valve leaflets are comparatively reasonable. The ellipsoidal and spherical valve leaflets have the following advantages over the cylindrical leaflet valve, lower peak von-Mises stress, smaller stress concentration area, and relatively uniform stress distribution. This work is very helpful to manufacture reasonable shaped valvular leaflets，thus to prolong the lifetime of the bioprosthetic heart valve.

Hyperelastic Material Model Selection of Structural Silicone Sealants for Use in Finite Element Modeling

2017 ◽  
Author(s):  
Larry D. Carbary ◽  
Jon H. Kimberlain ◽  
John C. Oliva
Keyword(s):  
Finite Element ◽  
Material Model ◽  
Hyperelastic Material ◽  
Model Parameters ◽  
Element Analysis ◽  
Structural Silicone ◽  
Lab Experiments ◽  
Hyperelastic Model ◽  
Hyperelastic Models ◽  
Selection Of

Hyperelastic material model parameters have been developed to capture the behavior of silicone based construction sealants. Modern commercially available finite element analysis software makes it quite accessible to develop hyperelastic material models, automating the process of curve-fitting experimental lab data to specific hyperelastic formulations. However, the process of selecting a particular hyperelastic model from those supported is not straightforward. Here, a series of lab experiments are employed to guide the selection of the hyperelastic model that best describes various structural silicone glazings. A total of 10 different sealants are characterized with discussion of variations among the models. Comparisons of the best performing hyperelastic models for the different sealants are presented. Finally, an application is described in which these hyperelastic models have begun to be implemented in practice.

XFEM Fracture Analysis of 2-D Plastically Graded Domain With Thermo-Mechanical J-Integral

2020 ◽  
Author(s):  
Margi Gajjar ◽  
Himanshu Pathak
Keyword(s):  
Partition Of Unity ◽  
Material Model ◽  
Computational Method ◽  
Discrete Equation ◽  
Isotropic Hardening ◽  
Plasticity Condition ◽  
Fracture Parameter ◽  
J Integral ◽  
Von Mises ◽  
Plastically Graded

Abstract Many engineering components fail in the presence of service loads like thermal residual stresses and thermomechanical loading. An accurate evaluation of the fracture parameter (J-integral) at the crack tip is essential for the safe design of structures. In this work, a novel computational method called the Extended Finite Element Method (XFEM) has been implemented to analyze the plastically graded material (PGM) subjected to thermal and thermo-mechanical loading. For crack discontinuity modeling, a partition of unity enrichment concept can be employed with additional mathematical functions like Heaviside and branch enrichment for crack discontinuity and stress field gradient, respectively. The modeling of the stressstrain relationship of material has been done using the Ramberg-Osgood material model. The isotropic hardening and Von-Mises yield criteria have been considered to check the plasticity condition. The variation in plasticity properties for PGM has been modeled by exponential law. Further, the nonlinear discrete equation has been numerically solved using a Newton-Rhapson iterative scheme.

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