Computational Algorithms for a Damage-Coupled Cyclic Viscoplasticity Material Model

2005 ◽  
Author(s):  
Aihong A. (Rachel) Zhao ◽  
C. L. Chow
Keyword(s):  
Material Model ◽  
Fatigue Tests ◽  
Accurate Solution ◽  
Primary Objective ◽  
Single Step ◽  
Tensile Creep ◽  
Integration Scheme ◽  
Single Element ◽  
Implicit Algorithm ◽  
Semi Empirical

The primary objective of the investigation is to develop efficient and robust computational schemes for a damage-coupled cyclic thermoviscoplasticity model for solder material. Three constitutive integration algorithms, Euler, modified Euler and semi-implicit algorithm for the model are examined. The three algorithms for the model are coded in the commercial finite element (FE) code ABAQUS (version 6.21) via the user-defined material subroutine UMAT. Two single-step algorithms of the substep scheme are applied for the modified Euler algorithm to control the error in the integration of constitutive laws. A semi-empirical formulation is established for an adaptive time stepping algorithm that is based on the Euler algorithm. Single-element, miniature specimen and notched specimen simulations have been conducted to compare with the test results, which include monotonic tensile, creep and fatigue tests of 63Sn-37Pb solder. It is observed that the explicit algorithm consistently requires much less CPU time than others. The modified Euler algorithm has shown on the other hand to be not only efficient but also accurate. The semi-implicit algorithm yields accurate solution. It is worth noting that the method is also effective when an appropriate integration scheme is chosen.

Unsteady Flow Simulations of a Transonic Nozzle and Cascade for a Time-Dependent Boundary Flow

2002 ◽  
Author(s):  
Erdal Turkbeyler
Keyword(s):  
Shock Wave ◽  
Unsteady Flow ◽  
Flow Analysis ◽  
Internal Flow ◽  
Wave Mode ◽  
Accurate Solution ◽  
Single Step ◽  
Integration Scheme ◽  
Inlet Flow ◽  
Flow Fluctuations

In this study we investigate unsteady compressible internal flow caused by flow fluctuations at an inlet or outlet flow-boundary. A finite-volume time-marching method has been developed for the unsteady flow analysis. This paper presents the proposed method and reports the results of a numerical investigation into the effects of a time-varying back pressure to a two-dimensional transonic nozzle and of a pulsating inlet flow to a transonic three-dimensional cascade of tapered blades. The computational model is based on a solution of the unsteady Euler equations for compressible flow. The time accurate solution is advanced by an explicit single-step second order time integration scheme. It has been found that the flow fluctuations at flow boundaries can cause strong unsteady effects on the operation of nozzles and cascades. Two modes of operation have been predicted for the unsteady flow in the nozzle: an upstream moving shock wave (mode-A) and an oscillating shock wave (mode-B). The results for the cascade have shown that the pulsating inlet flow causes the shock wave to originate, to move upstream and weaken over the period; the supersonic region on the blade surface varies continuously. The instantaneous mass flow rates and shock motions have been determined for them; they are important for their design and performance calculations.

An Efficient Algorithm for Damage-Coupled Visco-Plastic Fatigue Model

2004 ◽  
Author(s):  
A. H. Zhao ◽  
C. L. Chow
Keyword(s):  
Error Control ◽  
Three Dimensional ◽  
Numerical Algorithms ◽  
Fatigue Loading ◽  
Material Model ◽  
Tensile Creep ◽  
Local Error ◽  
Single Element ◽  
Numerical Examples ◽  
Uniaxial Test

The paper describes the development of an efficient and robust numerical algorithm for a damage-coupled visco-plastic-fatigue material model. The material chosen for the investigation is a eutectic material, Sn-Pb solder, exhibiting strain-softening behavior. The numerical algorithms employs a modified explicit method with adaptive sub-stepping based on the local error control for which the stress (constitutive) Jacobian explicit solution is derived. The algorithm is implemented in a commercial finite element (FE) code ABAQUS (Version 6.2) via its user-defined material subroutine. The validity of the algorithm is examined with several numerical examples, including (i) single-element simulations for uniaxial test, tensile creep, and fatigue simulations to attain an optimized algorithm, and (ii) two three-dimensional analyses of a miniature specimen under monotonic tensile loading and fatigue loading. The numerical examples illustrate the effectiveness of the modified explicit algorithm in predicting cyclic thermoviscoplastic behavior of a solder material. The algorithm is considered a generalized methodology that can be readily applied characterize thermoviscoplastic behavior and fatigue life of similar materials.

A Finite Element Procedure of a Cyclic Thermoviscoplasticity Model for Solder and Copper Interconnects

1998 ◽  
Vol 120 (1) ◽  
pp. 24-34 ◽  
Author(s):  
C. Fu ◽  
D. L. McDowell ◽  
I. C. Ume
Keyword(s):  
Finite Element ◽  
Electronic Packaging ◽  
Copper Interconnects ◽  
Implicit Time ◽  
Integration Scheme ◽  
Single Element ◽  
Ofhc Copper ◽  
Computation Efficiency ◽  
Backward Euler ◽  
Finite Element Procedure

A finite element procedure using a semi-implicit time-integration scheme has been developed for a cyclic thermoviscoplastic constitutive model for Pb-Sn solder and OFHC copper, two common metallic constituents in electronic packaging applications. The scheme has been implemented in the commercial finite element (FE) code ABAQUS (1995) via the user-defined material subroutine, UMAT. Several single-element simulations are conducted to compare with previous test results, which include monotonic tensile tests, creep tests, and a two-step ratchetting test for 62Sn36Pb2Ag solder; a nonproportional axial-torsional test and a thermomechanical fatigue (TMF) test for OFHC copper. At the constitutive level, we also provide an adaptive time stepping algorithm, which can be used to improve the overall computation efficiency and accuracy especially in large-scale FE analyses. We also compare the computational efforts of fully backward Euler and the proposed methods. The implementation of the FE procedure provides a guideline to apply user-defined material constitutive relations in FE analyses and to perform more sophisticated thermomechanical simulations. Such work can facilitate enhanced understanding thermomechanical reliability issue of solder and copper interconnects in electronic packaging applications.

scholarly journals Experimental and Numerical Characterization of the Cyclic Thermomechanical Behavior of a High Temperature Forming Tool Alloy

2010 ◽  
Vol 132 (5) ◽  
Author(s):  
Sean B. Leen ◽  
Aditya Deshpande ◽  
Thomas H. Hyde
Keyword(s):  
High Temperature ◽  
Life Prediction ◽  
Material Constant ◽  
Superplastic Forming ◽  
Material Model ◽  
Fatigue Tests ◽  
Material Behavior ◽  
Future Application ◽  
Rate Dependent ◽  
Numerical Characterization

This paper describes high temperature cyclic and creep relaxation testing and modeling of a high nickel-chromium material (XN40F) for application to the life prediction of superplastic forming (SPF) tools. An experimental test program to characterize the high temperature cyclic elastic-plastic-creep behavior of the material over a range of temperatures between 20°C and 900°C is described. The objective of the material testing is the development of a high temperature material model for cyclic analyses and life prediction of SPF dies for SPF of titanium aerospace components. A two-layer viscoplasticity model, which combines both creep and combined isotropic-kinematic plasticity, is chosen to represent the material behavior. The process of material constant identification for this model is presented, and the predicted results are compared with the rate-dependent (isothermal) experimental results. The temperature-dependent material model is furthermore applied to simulative thermomechanical fatigue tests, designed to represent the temperature and stress-strain cycling associated with the most damaging phase of the die cycle. The model is shown to give good correlation with the test data, thus vindicating future application of the material model in thermomechanical analyses of SPF dies for distortion and life prediction.

scholarly journals Development of a genetic toolset for the highly engineerable and metabolically versatile Acinetobacter baylyi ADP1

2020 ◽  
Vol 48 (9) ◽  
pp. 5169-5182
Author(s):  
Bradley W Biggs ◽  
Stacy R Bedore ◽  
Erika Arvay ◽  
Shu Huang ◽  
Harshith Subramanian ◽  
...  
Keyword(s):  
Synthetic Biology ◽  
Carbon Sources ◽  
Primary Objective ◽  
Single Step ◽  
Chromosomal Protein ◽  
Acinetobacter Baylyi ◽  
Catabolic Repression ◽  
Chemical Manufacturing ◽  
Promoter Library ◽  
Acinetobacter Baylyi Adp1

Abstract One primary objective of synthetic biology is to improve the sustainability of chemical manufacturing. Naturally occurring biological systems can utilize a variety of carbon sources, including waste streams that pose challenges to traditional chemical processing, such as lignin biomass, providing opportunity for remediation and valorization of these materials. Success, however, depends on identifying micro-organisms that are both metabolically versatile and engineerable. Identifying organisms with this combination of traits has been a historic hindrance. Here, we leverage the facile genetics of the metabolically versatile bacterium Acinetobacter baylyi ADP1 to create easy and rapid molecular cloning workflows, including a Cas9-based single-step marker-less and scar-less genomic integration method. In addition, we create a promoter library, ribosomal binding site (RBS) variants and test an unprecedented number of rationally integrated bacterial chromosomal protein expression sites and variants. At last, we demonstrate the utility of these tools by examining ADP1’s catabolic repression regulation, creating a strain with improved potential for lignin bioprocessing. Taken together, this work highlights ADP1 as an ideal host for a variety of sustainability and synthetic biology applications.

Static and Dynamic Tooth Loading in Spur and Helical Geared Systems: Experiments and Code Validation

2000 ◽  
Author(s):  
Sébastien Baud ◽  
Philippe Velex
Keyword(s):  
Linear Time ◽  
Primary Objective ◽  
Integration Scheme ◽  
Spur Gears ◽  
Mesh Stiffness ◽  
Response Curves ◽  
Time Step ◽  
Contact Conditions ◽  
Rotor Systems ◽  
Contact Algorithm

Abstract The primary objective of this study is to validate a specific finite element code aimed at simulated dynamic tooth loading in geared rotor systems. Experiments have been conducted on a high-precision single stage spur and helical gear reducer with flexible shafts mounted on hydrostatic or hydrodynamic bearings. The numerical model is based on classical elements (shaft, lumped stiffnesses, ...) and on an original gear element which accounts for non-linear time-varying mesh stiffness, gear errors and tooth shape modifications. External and parametric excitations are derived from the instantaneous contact conditions between the mating flanks by using an iterative contact algorithm inserted in a time-step integration scheme. In a first step, experimental and numerical results at low speeds are compared and it is demonstrated that the proposed tooth mesh interface model is valid. Comparisons are then extended to dynamic fillet stresses on both spur and helical gears between 50–6000 rpm on pinion shaft. Despite a localized problem in the case of spur gears with one particular bearing arrangement, the broad agreement between the experimental and numerical response curves proves that the model is representative of the dynamic behavior of geared systems.

A Forward Explicit Algorithm With Automatic Error Control for a Cyclic Thermoviscoplastic Coupled With Damage Model of Sn-Pb Solder

2005 ◽  
Author(s):  
A. H. Zhao
Keyword(s):  
Error Control ◽  
Damage Model ◽  
Time Integration ◽  
Fatigue Loading ◽  
Tensile Creep ◽  
Single Element ◽  
Step Size ◽  
Numerical Examples ◽  
Explicit Algorithm ◽  
Uniaxial Test

A self-correcting forwards gradient time integration procedure is formulated for the integration of a unified viscoplastic constitutive coupled with damage model for a eutectic solder alloy under cyclic fatigue loading. The procedure has been implemented numerically in the commercial finite element (FE) code ABAQUS (Version 6.2) via the user-defined material subroutine. The stress (constitutive) Jacobian explicit solution is derived. Schemes of the algorithm are verified by a series of numerical examples, including (1) Single-element simulations for uniaxial test, tensile creep, and fatigue simulations to reveal the optimum combination of the user-specified tolerance and the prescribed load step size to obtain a desired accuracy at a minimum cost. (2) Two three-dimensional analyses for monotonic tensile loading and fatigue loading were conducted for a miniature specimen of solder to show the capability of the proposed procedure to deal with thermomechanical loading. (3) Simulation of a shear notched specimen under monotonic loading was compared with the test to illustrate the ability of this algorithm for the specimen that has a serious damage region. The numerical examples illustrated that the explicit algorithm as well as empirical rule for adaptive time increment is effective for simulating cyclic thermoviscoplastic behavior of solder. The research can be applied to the simulation of viscoplasic behavior and fatigue life of softening materials.

scholarly journals Fatigue behaviour of open-hole samples and automotive mini-structures made of woven glass-fibre-reinforced polyamide 6,6

2018 ◽  
Vol 165 ◽  
pp. 07007
Author(s):  
Amélie Malpot ◽  
Fabienne Touchard ◽  
Sébastien Bergamo ◽  
Catherine Peyrac ◽  
Richard Montaudon ◽  
...  
Keyword(s):  
Acoustic Emission ◽  
Fatigue Behaviour ◽  
Fatigue Tests ◽  
Thermoplastic Composite ◽  
Semiempirical Model ◽  
Open Hole ◽  
Automotive Parts ◽  
Glass Fibre Reinforced ◽  
Semi Empirical ◽  
Non Destructive

In the automotive industry, the integration of thermoplastic composite components represents a high-potential solution to the mass reduction challenge. In this study, a woven glassfibre-reinforced composite with a polyamide 6,6 matrix is considered for the purpose of being integrated into automotive parts. Tension-tension fatigue tests were conducted on [(0/90)3] openhole samples. These tests were instrumented with non-destructive techniques, namely acoustic emission and infrared thermography. Acoustic emission results showed fibre-matrix debonding and fibre breakages in open-hole samples, located around the hole. Furthermore, 3-point bending fatigue tests were performed on “omega” mini-structures. A semi-empirical model was used in order to predict the fatigue lives of both open-hole coupons and automotive mini-structures. Predictions of the model for open-holes samples underestimate experimental fatigue lives. Nevertheless, the semiempirical model showed good results for the fatigue life prediction of composite mini-structures.

Development of Noninteraction Material Models With Cyclic Hardening

2016 ◽  
Vol 138 (4) ◽  
Author(s):  
Thomas Bouchenot ◽  
Bassem Felemban ◽  
Cristian Mejia ◽  
Ali P. Gordon
Keyword(s):  
Elevated Temperatures ◽  
Kinematic Hardening ◽  
Critical Role ◽  
Constitutive Models ◽  
Cyclic Hardening ◽  
Material Model ◽  
General Purpose ◽  
Pressure Vessels ◽  
Single Element ◽  
Critical Components

Simulation plays a critical role in the development and evaluation of critical components that are regularly subjected to mechanical loads at elevated temperatures. The cost, applicability, and accuracy of either numerical or analytical simulations are largely dependent on the material model chosen for the application. A noninteraction (NI) model derived from individual elastic, plastic, and creep components is developed in this study. The candidate material under examination for this application is 2.25Cr–1Mo, a low-alloy ferritic steel commonly used in chemical processing, nuclear reactors, pressure vessels, and power generation. Data acquired from prior research over a range of temperatures up to 650 °C are used to calibrate the creep and plastic components described using constitutive models generally native to general-purpose fea. Traditional methods invoked to generate constitutive modeling coefficients employ numerical fittings of hysteresis data, which result in values that are neither repeatable nor display reasonable temperature dependence. By extrapolating simplifications commonly used for reduced-order model approximations, an extension utilizing only the cyclic Ramberg–Osgood (RO) coefficients has been developed. This method is used to identify the nonlinear kinematic hardening (NLKH) constants needed at each temperature. Single-element simulations are conducted to verify the accuracy of the approach. Results are compared with isothermal and nonisothermal literature data.

scholarly journals Numerical studies on the heat dissipation process in elastomers under rotating loading direction

2021 ◽  
Author(s):  
M. Abdelmoniem ◽  
B. Yagimli
Keyword(s):  
Heat Dissipation ◽  
Viscoelastic Model ◽  
Material Model ◽  
Fatigue Tests ◽  
Shear Loading ◽  
The Self ◽  
Self Heating ◽  
Applied Loading ◽  
User Subroutine ◽  
Numerical Studies

AbstractElastomeric components such as car bearings and vibration dampers are subjected to dynamic loads with various amplitudes and loading directions during operation. To better understand the lifetime expectancy of these components it is required to implement a material model that sufficiently accounts for the material thermo-mechanical behaviour. This paper implements a finite viscoelastic model which includes heat dissipation and addresses the effect of inelasticity on the self-heating and the applied loading conditions. The material model is implemented in a user subroutine and finite element calculations are carried out on a simple shear loading with rotating directions. The self-heating effect and the resulting variation of the dissipation induced forces are shown and discussed. With the aid of the presented material model, thermo-mechanically coupled simulations can be performed. Based on the results, the required loading limits and boundary conditions for the mechanical fatigue tests can be defined to minimise the thermal fatigue effects.

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