Energy-based numerical modeling of the strain rate effect on fracture toughness of SA508 Gr. 1a

2017 ◽  
Vol 52 (3) ◽  
pp. 177-189 ◽  
Author(s):  
Hyun-Suk Nam ◽  
Yun-Jae Kim ◽  
Jin-Weon Kim ◽  
Jong-Sung Kim
Keyword(s):  
Fracture Toughness ◽  
Strain Rate ◽  
Damage Model ◽  
Type Model ◽  
Fracture Toughness Test ◽  
Ductile Tearing ◽  
Rate Dependent ◽  
Energy Concept ◽  
Axial Fracture ◽  
Dynamic Loading Conditions

This article presents an energy-based method to simulate ductile tearing under dynamic loading conditions. The strain rate–dependent material properties are characterized by the Johnson–Cook-type model. The damage model is defined based on the multi-axial fracture strain energy concept. The proposed damage model is applied to simulate the fracture toughness test of SA508 Gr. 1a under four different test speeds. Simulated results show a good overall agreement with the experimental results.

Ductile Tearing Simulation of Circumferential Cracked Pipe Under Cyclic Loading Using Damage Criteria Determined by Monotonic Pipe Test Data

2018 ◽  
Author(s):  
Jin-Ha Hwang ◽  
Gyo-Geun Youn ◽  
Naoki Miura ◽  
Yun-Jae Kim
Keyword(s):  
Fracture Toughness ◽  
Cyclic Loading ◽  
Ductile Fracture ◽  
Test Data ◽  
Strain Energy ◽  
Fracture Strain ◽  
Damage Model ◽  
Fracture Toughness Test ◽  
Ductile Tearing ◽  
Damage Criteria

To evaluate the structural integrity of nuclear power plant piping, it is important to predict ductile tearing of circumferential cracked pipe from the view point of Leak-Before-Break concept under seismic conditions. CRIEPI (Central Research Institute of Electric Power Industry) conducted fracture test on Japanese carbon steel (STS410) circumferential through-wall cracked pipes under monotonic or cyclic bending load in room temperature. Cyclic loading test conducted variable experimental conditions considering effect of stress ratio and amplitude. In the previous study, monotonic fracture pipe test was simulated by modified stress-strain ductile damage model determined by C(T) specimen fracture toughness test. And, ductile fracture of pipe under cyclic loading simulated using damage criteria based on fracture strain energy from C(T) specimen test data. In this study, monotonic pipe test result is applied to determination of damage model based on fracture strain energy, using finite element analysis, without C(T) specimen fracture toughness test. Ductile fracture of pipe under variable cyclic loading conditions simulates using determined fracture energy damage model from monotonic pipe test.

J-R Curve Prediction of Pre-Strained Stainless Steel 316 Material Using FE Damage Analysis Method

2018 ◽  
Author(s):  
Jun-Min Seo ◽  
Ji-Soo Kim ◽  
Yun-Jae Kim
Keyword(s):  
Experimental Data ◽  
Fracture Toughness ◽  
Damage Model ◽  
Damage Analysis ◽  
Fracture Toughness Test ◽  
Toughness Test ◽  
Cold Worked ◽  
Axial Fracture ◽  
Stainless Steel 316 ◽  
Strain Model

In this study, a method to predict J-R curve of SUS316 material using FE damage analysis is proposed. As experimental data, tensile and fracture toughness test results of cold worked SUS316 are used. The damage model used in this study is multi-axial fracture strain model and the model is determined by simulating the tensile and fracture toughness test according to the procedure in R6 code [1]. A pre-strain constant is newly introduced to consider pre-strain damage caused by the pre-strain, and the damage for various degrees of pre-strain are calculated. As a result, the predicted J-R curves using FE damage model show good agreement with the experimental data.

scholarly journals Rate Dependent Multicontinuum Progressive Failure Analysis of Woven Fabric Composite Structures under Dynamic Impact

2004 ◽  
Vol 11 (2) ◽  
pp. 103-117 ◽  
Author(s):  
James Lua ◽  
Christopher T. Key ◽  
Shane C. Schumacher ◽  
Andrew C. Hansen
Keyword(s):  
Composite Materials ◽  
Strain Rate ◽  
Dynamic Loading ◽  
Damage Model ◽  
Woven Fabric ◽  
Loading Conditions ◽  
Rate Dependent ◽  
Fabric Composite ◽  
Dynamic Loading Conditions ◽  
Marine Composite

Marine composite materials typically exhibit significant rate dependent response characteristics when subjected to extreme dynamic loading conditions. In this work, a strain-rate dependent continuum damage model is incorporated with multicontinuum technology (MCT) to predict damage and failure progression for composite material structures. MCT treats the constituents of a woven fabric composite as separate but linked continua, thereby allowing a designer to extract constituent stress/strain information in a structural analysis. The MCT algorithm and material damage model are numerically implemented with the explicit finite element code LS-DYNA3D via a user-defined material model (umat). The effects of the strain-rate hardening model are demonstrated through both simple single element analyses for woven fabric composites and also structural level impact simulations of a composite panel subjected to various impact conditions. Progressive damage at the constituent level is monitored throughout the loading. The results qualitatively illustrate the value of rate dependent material models for marine composite materials under extreme dynamic loading conditions.

scholarly journals A Strain Rate Dependent Progressive Damage Model for Carbon Fiber Woven Composites under Low Velocity Impact

2021 ◽  
Vol 2101 (1) ◽  
pp. 012073
Author(s):  
Xueyao Hu ◽  
Jiaojiao Tang ◽  
Wei Xiao ◽  
Kepeng Qu
Keyword(s):  
Strain Rate ◽  
Damage Model ◽  
Low Velocity Impact ◽  
Woven Composites ◽  
Progressive Damage ◽  
Low Velocity ◽  
Velocity Impact ◽  
Rate Dependent ◽  
Plane Direction ◽  
Progressive Damage Model

Abstract A progressive damage model was presented for carbon fiber woven composites under low velocity impact, considering the strain rate sensitivity of both mechanical properties and failure mechanisms. In this model, strain rate dependency of elastic modulus and nominal strength along in-plane direction are considered. Based on the Weibull distribution, stiffness progressive degradation is conducted by introducing strain rate dependent damage variables for distinct damage modes. With the model implemented in ABAQUS/Explicit via user-defined material subroutine (VUMAT), the mechanical behavior and possible damage modes of composites along in-plane direction can be determined. Furthermore, a bilinear traction separation model and a quadratic stress criterion are applied to predict the initiation and evolution of interlaminar delamination. Comparisons are made between the experimental results and numerical simulations. It is shown that the mechanical response and damage characteristics under low velocity impact, such as contact force history and delamination, are more consistent with the experimental results when taken the strain rate effect into consideration.

scholarly journals Extension of Flow Behaviour and Damage Models for Cast Iron Alloys with Strain Rate Effect

2020 ◽  
Author(s):  
Chuang Liu ◽  
Dongzhi Sun ◽  
Xianfeng Zhang ◽  
Florence Andrieux ◽  
Tobias Gerster
Keyword(s):  
Cast Iron ◽  
Constitutive Model ◽  
Strain Rate ◽  
Mechanical Behavior ◽  
Damage Model ◽  
Iron Alloys ◽  
Strain Rate Range ◽  
Strain Rates ◽  
Damage Models ◽  
Rate Dependent

Abstract Cast iron alloys with low production cost and quite good mechanical properties are widely used in the automotive industry. To study the mechanical behavior of a typical ductile cast iron (GJS-450) with nodular graphite, uni-axial quasi-static and dynamic tensile tests at strain rates of 10− 4, 1, 10, 100, and 250 s− 1 were carried out. In order to investigate the effects of stress state, specimens with various geometries were used in the experiments. Stress–strain curves and fracture strains of the GJS-450 alloy in the strain-rate range of 10− 4 to 250 s− 1 were obtained. A strain rate-dependent plastic flow law based on the Voce model is proposed to describe the mechanical behavior in the corresponding strain-rate range. The deformation behavior at various strain rates is observed and analyzed through simulations with the proposed strain rate-dependent constitutive model. The available damage model from Bai and Wierzbicki is extended to take the strain rate into account and calibrated based on the analysis of local fracture strains. The validity of the proposed constitutive model including the damage model was verified by the corresponding experimental results. The results show that the strain rate has obviously nonlinear effects on the yield stress and fracture strain of GJS-450 alloys. The predictions with the proposed constitutive model and damage models at various strain rates agree well with the experimental results, which illustrates that the rate-dependent flow rule and damage models can be used to describe the mechanical behavior of cast iron alloys at elevated strain rates.

scholarly journals Numerical simulation and experimental validation of ductile tearing in A106 Gr. B piping system under simulated seismic loading conditions

2018 ◽  
Vol 233 (1) ◽  
pp. 28-38 ◽  
Author(s):  
Hyun-Suk Nam ◽  
Gyo-Geun Youn ◽  
Jong-Min Lee ◽  
Hune-Tae Kim ◽  
Yun-Jae Kim
Keyword(s):  
Loading Condition ◽  
Experimental Validation ◽  
Damage Model ◽  
Time History ◽  
Seismic Loading ◽  
Piping System ◽  
Fracture Toughness Test ◽  
Ductile Tearing ◽  
History Analysis ◽  
Dynamic Time

This work presents finite element ductile tearing simulation and experimental validation of a piping system with a circumferential surface cracked (SC) A106 Gr. B pipe under simulated seismic loading condition. The damage model for simulation is based on the multiaxial fracture strain energy. The parameters in the damage model are determined from tensile and fracture toughness test results under the monotonic loading condition. For the system dynamic time history analysis, the Rayleigh damping model is employed. For cyclic constitutive equations, two models were considered to confirm its sensitivity. Predicted crack initiation and ductile tearing agree well with the experimental results.

Sign in / Sign up

Export Citation Format

Share Document