Analyzing Fracture Behavior of Beam-Column Joints Using Micromechanical Fracture Models

2015 ◽  
Vol 744-746 ◽  
pp. 3-7
Author(s):  
Chen Zhang ◽  
Yu Ping Sun ◽  
Ju Tao Zhang ◽  
Yu Gu
Keyword(s):  
Finite Element ◽  
Plastic Strain ◽  
Fracture Behavior ◽  
Equivalent Plastic Strain ◽  
Stress Triaxiality ◽  
Bolted Connection ◽  
Finite Element Software ◽  
Maximum Value ◽  
Fracture Models ◽  
Welded Connection

The micromechanical fracture models were used to study the fracture behavior of the welded connection and welded-bolted connection joints. The Void Growth Model was implemented in commercial finite element software ABAQUS through the user-defined subroutines. The results predicted that cracks initiated at the edge of the welds and extended along the length and thickness of the welds. Comparing the effects of equivalent plastic strain and stress triaxiality for the fracture of the first failure element of both beam-to-column joints, we found that the equivalent plastic strain grew linearly as the loads increased and the weld of the lower flange generated cracks when the stress triaxiality increased at maximum value.

scholarly journals Strain Rate-Dependent Constitutive and Low Stress Triaxiality Fracture Behavior Investigation of 6005 Al Alloy

2018 ◽  
Vol 2018 ◽  
pp. 1-14 ◽  
Author(s):  
Yong Peng ◽  
Xuanzhen Chen ◽  
Shan Peng ◽  
Chao Chen ◽  
Jiahao Li ◽  
...  
Keyword(s):  
Flow Stress ◽  
Plastic Strain ◽  
Strain Rate ◽  
Fracture Behavior ◽  
Equivalent Plastic Strain ◽  
Stress Triaxiality ◽  
Tensile Tests ◽  
Uniaxial Tensile ◽  
Strain Rates ◽  
Stress States

In order to study the dynamic and fracture behavior of 6005 aluminum alloy at different strain rates and stress states, various tests (tensile tests at different strain rates and tensile shearing tests at five stress states) are conducted by Mechanical Testing and Simulation (MTS) and split-Hopkinson tension bar (SHTB). Numerical simulations based on the finite element method (FEM) are performed with ABAQUS/Standard to obtain the actual stress triaxialities and equivalent plastic strain to fracture. The results of tensile tests for 6005 Al show obvious rate dependence on strain rates. The results obtained from simulations indicate the feature of nonmonotonicity between the strain to fracture and stress triaxiality. The equivalent plastic strain reduces to a minimum value and then increases in the stress triaxiality range from 0.04 to 0.30. A simplified Johnson-Cook (JC) constitutive model is proposed to depict the relationship between the flow stress and strain rate. What is more, the strain-rate factor is modified using a quadratic polynomial regression model, in which it is considered to vary with the strain and strain rates. A fracture criterion is also proposed in a low stress triaxiality range from 0.04 to 0.369. Error analysis for the modified JC model indicates that the model exhibits higher accuracy than the original one in predicting the flow stress at different strain rates. The fractography analysis indicates that the material has a typical ductile fracture mechanism including the shear fracture under pure shear and the dimple fracture under uniaxial tensile.

The Comparison between Continuous Confined Strip Shearing (C2S2) and ECAP Conform in Regard to Equivalent Plastic Strain Distribution for Al 1100

2012 ◽  
Vol 05 ◽  
pp. 400-409 ◽  
Author(s):  
A. R. Shahab ◽  
S. A. A. Akbari Mousavi ◽  
Sh. Ranjbar Bahadori ◽  
S. M. Ebrahimi
Keyword(s):  
Finite Element ◽  
Plastic Strain ◽  
Strain Distribution ◽  
Pure Aluminum ◽  
Continuous Process ◽  
Processing Condition ◽  
Equivalent Plastic Strain ◽  
Finite Element Software ◽  
Angular Pressing ◽  
Commercially Pure

During the last years lots of efforts have been done to industrialize equal channel angular pressing (ECAP) technique. Both Continuous Confined Strip Shearing (C2S2) and ECAP-Conform methods are rather recent techniques, making a continuous process from ECAP method. In present study both mentioned processes were simulated with ABAQUS Finite Element software for commercially pure aluminum. During C2S2 process the sample gradually experienced equivalent plastic strain (PEEQ) of 0.13 at initial stages of bending, while during ECAP-Conform the sample underwent rather sudden magnitude of strain of about 0.52 at primary stages, and it remained constant during the rest of the process. The final magnitude of the PEEQ differed significantly between two processes, as it was 0.86 and 1.36 in C2S2 and ECAP-Conform, respectively. Therefore, in the same processing condition employing the ECAP-Conform method led to a finer microstructure in comparison with C2S2 technique.

scholarly journals Investigation of the Thickness Differential on the Formability of Aluminum Tailor Welded Blanks

Metals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 875
Author(s):  
Jie Wu ◽  
Yuri Hovanski ◽  
Michael Miles
Keyword(s):  
Experimental Data ◽  
Finite Element ◽  
Numerical Model ◽  
Plastic Strain ◽  
Finite Element Model ◽  
Equivalent Plastic Strain ◽  
Element Model ◽  
Dome Height ◽  
Tailor Welded Blanks ◽  
Simulation Results

A finite element model is proposed to investigate the effect of thickness differential on Limiting Dome Height (LDH) testing of aluminum tailor-welded blanks. The numerical model is validated via comparison of the equivalent plastic strain and displacement distribution between the simulation results and the experimental data. The normalized equivalent plastic strain and normalized LDH values are proposed as a means of quantifying the influence of thickness differential for a variety of different ratios. Increasing thickness differential was found to decrease the normalized equivalent plastic strain and normalized LDH values, this providing an evaluation of blank formability.

Finite Element Analysis on Incremental Launching Construction for Steel Box Girder

2013 ◽  
Vol 671-674 ◽  
pp. 974-979
Author(s):  
Jie Dai ◽  
Jin Di ◽  
Feng Jiang Qin ◽  
Min Zhao ◽  
Wen Ru Lu
Keyword(s):  
Finite Element ◽  
Bending Moment ◽  
Internal Force ◽  
Element Analysis ◽  
Box Girder ◽  
Finite Element Software ◽  
Cable Stayed Bridge ◽  
Steel Box Girder ◽  
Maximum Value ◽  
Negative Bending

For steel box girder of cable-stayed bridge, which using incremental launching method, during the launching process, structural system and boundary conditions were changing, structure mechanical behaviors were complex. It was necessary to conduct a comprehensive analysis on internal force and deformation of the whole structure during the launching process. Took a cable-stayed bridge with single tower, double cable planes and steel box girder in China as an example; finite element software MIDAS Civil 2010 was used to establish a model for steel box girder, simulation analysis of the entire incremental launching process was carried out. Variation rules and envelopes of the internal force, stress, deformation and support reaction were obtained. The result showed that: the maximum value of positive bending moment after launching complete was 60% of the maximum value of positive bending moment during the launching process. The maximum value of negative bending moment after launching complete was 78% of the maximum value of negative bending moment during the launching process.

Experimental and numerical study on largely perforated steel shear plates with rectangular tube–shaped links

2020 ◽  
Vol 23 (15) ◽  
pp. 3307-3322 ◽  
Author(s):  
H Monsef Ahmadi ◽  
MR Sheidaii ◽  
H Boudaghi ◽  
G De Matteis
Keyword(s):  
Finite Element ◽  
Numerical Study ◽  
Equivalent Plastic Strain ◽  
Absorption Capacity ◽  
Hysteretic Behavior ◽  
Steel Plate Shear Wall ◽  
Grid Systems ◽  
Finite Element Software ◽  
Internal Link ◽  
Rectangular Tube

Steel plate shear wall is one of the most effective dissipation systems which are commonly used in buildings. In order to improve the hysteretic behavior of shear panels, large perforation patterns may be applied, transforming the shear plate into a sort of grid systems, where plastic deformations are concentrated on specific internal link elements. This study investigates the behavior of grid systems loaded in shear where the internal links are created by cutting out internal parts, leaving rectangular tube–shaped link elements. The influence of internal link geometry on the cyclic performance of the systems is investigated experimentally. To this purpose, two specimens that varied in the width of links were fabricated and tested. The results indicate that any increase in the width of links leads to the growth of the ultimate strength, stiffness, and energy absorption capacity. Likewise, the stress distribution and fracture tendency of the tested specimens have been simulated by the finite element software (ABAQUS) and validated according to the experimental results. Based on finite element results, a suitable analytical formulation for the prediction of the shear strength at several shear deformation demands, considering the effect of thickness of the link, has been provided. Moreover, to improve the fracture tendency of the specimens, butterfly-shaped links, which varied in the middle length, were applied. The obtained results, which have been interpreted by considering the equivalent plastic strain value, prove that the shear panel behavior improves significantly when butterfly-shaped links are considered.

Influence of Indent Geometry on Repeated Two-Dimensional Rolling Contact

1995 ◽  
Vol 117 (4) ◽  
pp. 655-659 ◽  
Author(s):  
V. Gupta ◽  
P. Bastias ◽  
G. T. Hahn ◽  
C. A. Rubin
Keyword(s):  
Finite Element ◽  
Plastic Strain ◽  
Equivalent Plastic Strain ◽  
Element Model ◽  
Rolling Contact ◽  
Surface Coatings ◽  
Surface Irregularity ◽  
Plastic Strains ◽  
Two Dimensional ◽  
Finite Element Calculations

A “two-body,” elasto-plastic finite element model is employed to simulate repeated rolling contact in the presence of a surface irregularity. It is shown that the maximum Mises stress and equivalent plastic strain values in the substrate are related to the height of the pressure spikes. The results of the finite element calculations are used to derive generalizations about the influence of the indent geometry on the pressure spikes, peak cyclic plastic strains and their location below the surface. These relations can serve as guidelines for designing the depth and properties of surface coatings and modified layers.

An Experimental and Numerical Study on Forming Force, Fracture Behavior, and Strain States in Two Point Incremental Forming Process

2016 ◽  
Vol 725 ◽  
pp. 586-591
Author(s):  
Chen Hao Wang ◽  
William J.T. Daniel ◽  
Hai Bo Lu ◽  
Sheng Liu ◽  
Paul Anthony Meehan
Keyword(s):  
Plastic Strain ◽  
Fracture Behavior ◽  
Numerical Study ◽  
Equivalent Plastic Strain ◽  
Fem Simulation ◽  
Forming Force ◽  
Forming Process ◽  
Approaches To Study ◽  
Tool Diameter ◽  
Numerical Approaches

Two-point incremental sheet forming process (TPIF) is an emerging and promising manufacturing process for the production of complex geometries or customized functional sheet components. In this study, the single-pass TPIF process is investigated using experimental and numerical approaches to study the forming force evolution, fracture behavior and strain states with a varied wall angle hemisphere shape. It can be concluded that both the peak force and fracture depth increases with tool diameter and incremental depth in TPIF process. It seems the deformation mechanism or the failure mechanism is strongly dependent on particular forming conditions based on a failure parts morphology observation. FEM simulation results indicated that the major plastic strain is positive while the minor plastic strain is negative in the TPIF process on a hemiphere shape. it can be concluded that the strain increment and total equivalent plastic strain is affected by both tool diameter and incremental depth.

Evaluation of Thermal Stress Ratchet in Plastic FEA

2002 ◽  
Author(s):  
Yukinori Yamamoto ◽  
Norimichi Yamashita ◽  
Masaaki Tanaka
Keyword(s):  
Finite Element ◽  
Thermal Stress ◽  
Stress State ◽  
Plastic Strain ◽  
Axial Stress ◽  
Equivalent Plastic Strain ◽  
Hardening Material ◽  
Linear Temperature ◽  
Stress Evaluation ◽  
Elastic Core

Alternative stress evaluation criteria suitable for Finite Element Analysis (FEA) proposed by Okamoto et al. [1] have been studied by the Committee on Three Dimensional Finite Element Stress Evaluation (C-TDF) in Japan. Thermal stress ratchet criteria in plastic FEA are now under consideration. Two criteria are proposed: evaluating variations in plastic strain increments and evaluating variations in the width of elastic core. To verify the validity of these criteria, calculations were performed for several typical models in C-TDF [2]. This paper shows the results of a simple cylinder model. Cyclic plastic analyses were performed applying sustained internal pressure and alternating linear temperature distribution through the wall. Analyses were performed with various load ranges to evaluate the precise ratchet limit and its behavior across the limit. Both pressure and thermal stress were given parameters. In the analyses, Elastic-Perfectly-Plastic (EPP) material was used and also strain hardening material for comparison. The ratchet limit in the Code [3] is based on Miller’s theoretical analysis [4] for a cylinder assuming a uni-axial stress state, whereas real vessels are in multi-axial stress state. By our calculations, we also examined the ratchet limit in real vessels. The results show that for the cylinder in a multi-axial stress state, the ratchet limit rises 1.2 times the ratchet limit by the Code. The evaluation results show that variations in equivalent plastic strain increments can be used for ratchet criterion and ratcheting can be assessed by confirming the presence of elastic core in the second cycle.

scholarly journals Finite element modeling of sub-surface damage while machining aluminum based metal matrix composites

2021 ◽  
Vol 13 (12) ◽  
pp. 168781402110704
Author(s):  
Usama Umer ◽  
Hisham Alkhalefah ◽  
Mustufa Haider Abidi ◽  
Muneer Khan Mohammed ◽  
Hossam Kishawy
Keyword(s):  
Finite Element ◽  
Plastic Strain ◽  
Metal Matrix Composites ◽  
Metal Matrix ◽  
Equivalent Plastic Strain ◽  
Surface Damage ◽  
Computational Time ◽  
Matrix Composites ◽  
Particle Fracture ◽  
Machined Surface

Sub-surface damage during machining of aluminum-based metal matrix composites (MMCs) has been modeled using finite element models. These models are based on reinforcement particles size and volume fractions and particles are distributed uniformly in the metal matrix. In order to simulate particle debonding cohesive zone elements (CZE) have been incorporated along the parting line. In addition, failure criteria based on brittle fracture have been added for ceramic particles to simulate particle fracture. To reduce computational time and simplify the model both CZE and particle fracture is limited to the reinforced particles along the parting lines facing the tip of the cutting tool. The damage depth beneath the machined surface is measured by using the non-zero plastic strain values in the equivalent plastic strain contours obtained from the FE models. The results were compared against published experimental data and found to be in good agreement.

Evaluation of Ductile Cracking Criterion for Grade X100 Linepipe and Relationship to Large Scale Fracture Behavior

2003 ◽  
Author(s):  
Nobuyuki Ishikawa ◽  
Shigeru Endo ◽  
Alan Glover ◽  
David Horsley ◽  
Masao Toyoda
Keyword(s):  
Plastic Strain ◽  
Ductile Fracture ◽  
Fracture Behavior ◽  
Large Scale ◽  
Notch Root ◽  
Equivalent Plastic Strain ◽  
High Strength ◽  
Fracture Initiation ◽  
Linepipe Steels ◽  
Ductile Fracture Initiation

Recent developments in the manufacturing process of steel plate for high strength linepipe have enabled superior toughness to prevent brittle fracture of the pipe body. Techniques for non-destructive inspection have also improved, and large flaws that could lead to brittle fracture are highly unlikely in recent high strength pipelines. However, large amounts of plastic deformation can be expected in seismic or permafrost regions. Prevention of ductile fracture of the pipe body or weldment therefore becomes a key issue in defining the tensile strain limit. Ductile fracture is considered to occur by growth and coalescence of voids, and is affected by stress triaxiality and plastic straining at the cracked region. Although many studies have been carried out to evaluate ductile cracking criteria, its transferability to large-scale fracture behavior has not been thoroughly investigated. In this study, ductile cracking of high strength linepipe steels, Grade X80 and X100, was investigated. Notched round bar specimens with different notch root radii were tested to determine the precise conditions for initiation of ductile fracture. Stress and strain conditions at the notch regions were evaluated by FE analysis, and the “critical equivalent plastic strain” was defined at conditions corresponding to ductile fracture initiation in the experimental small specimen tests. Ductile crack initiation behavior was also determined for wide plate test specimens by making close observations of the notch root area. 3-D FE analysis of the wide plate tensile test showed that the equivalent plastic strain at the point of ductile fracture initiation was in close agreement with that in the notched round bas specimen. Thus, the “critical equivalent plastic strain,” determined by small notched round bar specimens, can be considered as a transferable criterion to predict large-scale fracture behavior in wide plate tests. Concepts of strain based design in terms of preventing ductile failure from a surface flaw by applying critical strain to cracking were also discussed in this paper. Results were compared to conventional grade linepipe steels and structural steels, showing that recent high strength linepipe steels have higher resistance to ductile cracking than conventional structural steels. In addition, 3-D FE analyses were used in a parametric study to determine the effects of Y/T and uniform strain on the onset of ductile cracking behaviour. The results of these analyses show the relative importance of materials properties on the resistance to ductile cracking.

Sign in / Sign up

Export Citation Format

Share Document