Ductile fracture of solder-Cu interface and inverse identification of its interfacial model parameters

2017 ◽  
Vol 114 ◽  
pp. 279-292 ◽  
Author(s):  
Yangjian Xu ◽  
Shuai Zhao ◽  
Guohui Jin ◽  
Xiaogui Wang ◽  
Lihua Liang
Keyword(s):  
Ductile Fracture ◽  
Model Parameters ◽  
Inverse Identification

A Micromechanics Approach to Assess Ductile Crack Initiation in Damaged Pipelines

2003 ◽  
Author(s):  
Claudio Ruggieri ◽  
Fernando F. Santos ◽  
Mitsuru Ohata ◽  
Masao Toyoda
Keyword(s):  
Ductile Fracture ◽  
Large Scale ◽  
Cell Model ◽  
High Strength ◽  
Void Coalescence ◽  
Model Parameters ◽  
Ductile Crack ◽  
Cracking Behavior ◽  
Damage Criterion ◽  
Limited Applicability

This study explores the capabilities of a computational cell framework into a 3-D setting to model ductile fracture behavior in tensile specimens and damaged pipelines. The cell methodology provides a convenient approach for ductile crack extension suitable for large scale numerical analyses which includes a damage criterion and a microstructural length scale over which damage occurs. Laboratory testing of a high strength structural steel provides the experimental stress-strain data for round bar and circumferentially notched tensile specimens to calibrate the cell model parameters for the material. The present work applies the cell methodology using two damage criterion to describe ductile fracture in tensile specimens: (1) the Gurson-Tvergaard (GT) constitutive model for the softening of material and (2) the stress-modified, critical strain (SMCS) criterion for void coalescence. These damage criteria are then applied to predict ductile cracking for a pipe specimen tested under cycling bend loading. While the methodology still appears to have limited applicability to predict ductile cracking behavior in pipe specimens, the cell model predictions of the ductile response for the tensile specimens show good agreemeent with experimental measurements.

Evaluations of Ductile and Cleavage Fracture Using Coupled GTN and Beremin Model in API X70 Pipelines Steel

2019 ◽  
Author(s):  
Youn-Young Jang ◽  
Ji-Hee Moon ◽  
Nam-Su Huh ◽  
Ki-Seok Kim ◽  
Woo-Yeon Cho ◽  
...  
Keyword(s):  
Ductile Fracture ◽  
Cleavage Fracture ◽  
Fracture Behavior ◽  
Pipeline Steel ◽  
Model Parameters ◽  
Experiment Data ◽  
Local Approach ◽  
Gtn Model ◽  
Weibull Parameters ◽  
X70 Pipeline Steel

Abstract This paper is aimed to characterize ductile and cleavage fracture behavior of API X70 pipeline steel and investigate applicability of a micro-damage mechanics model to simulate static and dynamic crack propagation of single-edge notched tension (SENT) and drop-weight tear test (DWTT) specimens, as well as a local approach to describe cleavage fracture behavior. Gurson-Tvergaard-Needleman (GTN) model was applied to simulate ductile fracture behavior of SENT and DWTT specimens, where GTN model has been widely known for well-established model to characterize micro-damage process of void nucleation, growth and coalescence. As for a local approach, Beremin model was considered to estimate probability of cleavage fracture. In this regard, this study was especially focused on abnormal fracture appearance of DWTT specimen. In the present study, firstly, experiment data from tensile specimen test was used to obtain plastic flow curve (i.e. stress and strain curve). And load-CMOD and J-integral/CTOD resistance curves obtained from SENT test were used to characterize static ductile fracture and calibrate GTN model parameters for X70 pipeline steel. And the calibrated GTN model parameters were verified by comparing experiment data from DWTT test such as load-displacement and crack length-time curves with those from FE analysis. To accommodate dynamic effect on material properties, rate-dependent stress-strain curves were considered in FE analyses. To describe cleavage fracture, the Weibull stress was calculated from FE analyses of DWTT and Weibull parameters were calibrated by comparing with probability distribution of cleavage fracture from experiment data of DWTT specimen. Using Weibull parameters, the whole of cleavage fracture probability can be estimated as ductile shear area of DWTT specimen increases.

Considering Anisotropic Material Behaviour of Sheet Metals for Ductile Fracture Prediction

2014 ◽  
Vol 1018 ◽  
pp. 229-236
Author(s):  
Andreas Sabathil ◽  
Ingo Heinle ◽  
Arnulf Lipp ◽  
Josef Meinhardt ◽  
Marion Merklein
Keyword(s):  
Ductile Fracture ◽  
Anisotropic Material ◽  
Isotropic Material ◽  
Fracture Prediction ◽  
Model Parameters ◽  
Suitable Model ◽  
Sheet Metals ◽  
Material Behaviour ◽  
Fracture Models ◽  
Body In White

In the manufacturing process of body in white components made from sheet metal it is state of the art to accompany the process by means of finite element analysis. A main criterion for determining a feasible tool design and process parameters is the prediction of material failure, which can be categorized in instability and ductile fracture. The ductile fracture failure mode is more likely to occur, as more advanced high strength steels and aluminium alloys are used for body in white components. Therefore various approaches have been presented to model ductile fracture over the past years. However, there is no guideline to determine which models are suitable for predicting ductile fracture. The same applies when it comes to choosing experiments and calibration of model parameters. A suitable model calibration is vital, as the fracture prediction depends on the determined model parameters. Usually an isotropic material behaviour is assumed for calibration of fracture models. However, sheet metals can show an anisotropic material behaviour due to the rolling process. Therefore it is arguable if an isotropic material model can be applied when fracture models are calibrated.

Assessment of Gurson-Tveergard-Needleman Model Under High Stress Triaxiality

2016 ◽  
Author(s):  
Jiru Zhong ◽  
Tong Xu ◽  
Kaishu Guan
Keyword(s):  
Ductile Fracture ◽  
Volume Fraction ◽  
Stress Triaxiality ◽  
Fracture Initiation ◽  
Tensile Specimen ◽  
Void Volume Fraction ◽  
Model Parameters ◽  
Gtn Model ◽  
Notched Specimens ◽  
Critical Void

The Gurson-Tveergard-Needleman (GTN) model has been widely used to describe ductile fracture. In this paper, a series of tensile tests were carried out on notched specimens to assess the GTN model. The GTN model parameters were calibrated from a smooth tensile specimen by a hybrid particle swarm optimization, and the reliability of the calibrated parameters was verified by the profile of the smooth tensile specimen. The calibrated parameters were used to predict the ductile fracture of notched specimens. A comparison of fracture initiation sites between simulations and experiments indicates that the GTN model has a good performance on predicting fracture initiation site but fails at predicting fracture moment. The assessment of the transformability of the GTN model parameters was performed by comparing the load-displacement curves between simulations and experiments. It is observed that the GTN model parameters are material constant, except the critical void volume fraction fc. The influence of stress triaxiality on the critical void volume fraction fc is also discussed.

scholarly journals Optimal Experimental Design for Inverse Identification of Conductive and Radiative Properties of Participating Medium

Energies ◽  
2021 ◽  
Vol 14 (20) ◽  
pp. 6593
Author(s):  
Hua Liu ◽  
Xue Chen ◽  
Zhongcan Chen ◽  
Caobing Wei ◽  
Zuo Chen ◽  
...  
Keyword(s):  
A Priori ◽  
Radiative Properties ◽  
Transient Temperature ◽  
Model Parameters ◽  
Inverse Identification ◽  
Error Sources ◽  
Temperature Probe ◽  
Sensor Position ◽  
Uncertain Model ◽  
Cramer Rao Bound

The conductive and radiative properties of participating medium can be estimated by solving an inverse problem that combines transient temperature measurements and a forward model to predict the coupled conductive and radiative heat transfer. The procedure, as well as the estimates of parameters, are not only affected by the measurement noise that intrinsically exists in the experiment, but are also influenced by the known model parameters that are used as necessary inputs to solve the forward problem. In the present study, a stochastic Cramér–Rao bound (sCRB)-based error analysis method was employed for estimation of the errors of the retrieved conductive and radiative properties in an inverse identification process. The method took into account both the uncertainties of the experimental noise and the uncertain model parameter errors. Moreover, we applied the method to design the optimal location of the temperature probe, and to predict the relative error contribution of different error sources for combined conductive and radiative inverse problems. The results show that the proposed methodology is able to determine, a priori, the errors of the retrieved parameters, and that the accuracy of the retrieved parameters can be improved by setting the temperature probe at an optimal sensor position.

scholarly journals Localized Necking Model for Punching Fracture Simulation in Unstiffened and Stiffened Panels

2021 ◽  
Vol 11 (9) ◽  
pp. 3774
Author(s):  
Sung-Ju Park ◽  
Kookhyun Kim
Keyword(s):  
Ductile Fracture ◽  
Fracture Initiation ◽  
Fracture Model ◽  
Model Parameters ◽  
Stiffened Panels ◽  
Plane Strain Tension ◽  
Localized Necking ◽  
Hardening Law ◽  
Numerical Predictions ◽  
Fracture Simulation

The ductile fracture of thin-shell structures was studied here using a localized necking model. The punching experiments for unstiffened and stiffened panels were compared with numerical predictions using a combined ductile fracture and localized necking model using shell elements. The plasticity and fracture model parameters of JIS G3131 SPHC steel were identified by performing calibration experiments on standard flat bars, notched tension, central hole tension, plane strain tension, and shear specimens. The plasticity beyond the onset of necking was modeled using the Swift hardening law. The damage indicator framework with a combined Hosford–Coulomb fracture model and the domain of shell-to-solid equivalence (DSSE) were adopted to characterize the fracture initiation. The model parameters were calibrated based on the loading paths to fracture initiation, which were extracted from a non-linear finite element (FE) analysis. The presented HC–DSSE model was validated using punch tests and was able to predict fracture initiation with good accuracy.

Evaluation and Validation of Methods to Determine Limit Strain States with Focus on Modeling Ductile Fracture

2014 ◽  
Vol 622-623 ◽  
pp. 265-272
Author(s):  
Andreas Sabathil ◽  
Ingo Heinle ◽  
A. Lipp ◽  
J. Meinhardt ◽  
M. Merklein
Keyword(s):  
Ductile Fracture ◽  
Sheet Metal ◽  
High Strength Steels ◽  
High Strength ◽  
Limit Strain ◽  
Model Parameters ◽  
Element Analysis ◽  
Advanced High Strength Steels ◽  
Validation Experiment ◽  
Body In White

In the manufacturing process of body in white components made from sheet metal it is state of the art to accompany the process by means of finite element analysis. A main criterion for determining a feasible tool design and production process parameters is the prediction of material failure, which can be categorized in instability and ductile fracture. The ductile fracture failure mode is more likely to occur, as more advanced high strength steels and aluminum alloys are used for body in white components. Therefore different approaches have been presented to model ductile fracture over the past years. This task is more challenging when the material is exposed to arbitrary loading paths that can occur in deep drawing processes. However there is no guideline for sheet metal forming applications to determine which models for predicting ductile fracture are suitable, which experiments are necessary and how calibration of model parameters and validation of model prediction can be performed. Additionally there is no standard established that prescribes the evaluation of limit strain states from experiments. Suitable limit strain states are a basic requirement for prediction of ductile fracture as they are used for calibration of fracture models. In this paper, two methods for evaluation of limit strains are discussed and applied to tensile specimens with circular hole and circular cut outs made from aluminum alloy AlSi0.6Mg0.5. One validation experiment is used to investigate failure prediction that is based on limit strain states from different evaluation methods.

Ductile Fracture Resistance Modeling Approach in Two High Grade Steels

2006 ◽  
Author(s):  
L. N. Pussegoda ◽  
A. Fredj ◽  
A. Dinovitzer ◽  
D. Horsley ◽  
D. Carlson
Keyword(s):  
Steady State ◽  
Crack Propagation ◽  
Ductile Fracture ◽  
Fracture Resistance ◽  
Fracture Propagation ◽  
Tension Test ◽  
Model Parameters ◽  
High Grade ◽  
Damage Mechanisms ◽  
Point Bend

Recent developments in ductile fracture resistance measures in high grade steels in the pipeline industry include the crack tip opening angle (CTOA) and “steady state” fracture propagation energy, using 3-point bend specimens. The CTOA has been found to be a function of specimen ligament size. Alternatives would be “steady state” fracture propagation energy, critical fracture strain and adoption of damage mechanisms. This paper focuses on modeling approaches for crack propagation using damage mechanisms. The tension test is used to “calibrate” the damage model parameters and applied to the crack propagation in a 3-point bend specimen in candidate high grade steels. The effects of using parameters developed from tension test and extending to a 3-point bend crack propagation scenario is discussed.

scholarly journals Modeling of Ductile Fracture for SS275 Structural Steel Sheets

2021 ◽  
Vol 11 (12) ◽  
pp. 5392
Author(s):  
Yonghyun Cho ◽  
Changkye Lee ◽  
Jurng-Jae Yee ◽  
Dong-Keon Kim
Keyword(s):  
Finite Element ◽  
Ductile Fracture ◽  
Structural Steel ◽  
Fracture Behavior ◽  
Weighted Average ◽  
Image Correlation ◽  
Model Parameters ◽  
Suitable Model ◽  
Element Analysis ◽  
Fracture Simulation

A series of earthquake events give impetus to research on the ductile fracture behavior of steel materials. In the last decades, many fracture models have been developed and utilized in the mechanical or aerospace engineering. Nevertheless, very little application to structural members used in the construction industry has been made due to the lack of a suitable model for the fracture behavior of constructional steel. This paper presents the experimental and finite element (FE) technique to predict ductile fracture in mild carbon structural steel (SS275) sheets, which has been widely used in building structures. The post-necking true stress–strain responses were successfully estimated using the weighted-average method. The Bao and Wierzbicki (BW) model, which requires only two model parameters, was selected for the identification of fracture locus. Each model parameter was calibrated from uniaxial tension and in-plane shear specimens with the aid of digital image correlation (DIC) and finite element analysis. Fracture simulation was then performed and validated based on the experimental results of the specimens under combined tension and shear stress state.

Sign in / Sign up

Export Citation Format

Share Document