Edge Fracture Prediction of Traditional and Advanced Trimming Processes for AA6111-T4 Sheets

2014 ◽  
Vol 136 (2) ◽  
Author(s):  
X. H. Hu ◽  
K. S. Choi ◽  
X. Sun ◽  
S. F. Golovashchenko
Keyword(s):  
Finite Element ◽  
Damage Model ◽  
Initiation Site ◽  
Formation Mechanisms ◽  
Sharp Corner ◽  
Adaptive Meshing ◽  
Crack Initiation Site ◽  
Aluminum Sheets ◽  
Quantitative Accuracy ◽  
Grain Aspect Ratio

This work examines the traditional and advanced trimming of AA6111-T4 aluminum sheets with finite element simulations. The Rice-Tracy damage model is used for the simulation with damage parameters estimated from experimental observation of grain aspect ratio near the fracture surface of trimmed parts. Fine meshes at the shearing zone, adaptive meshing, and adaptive contact techniques are used to accurately capture the contact interactions between the sharp corner of the trimming tools and the blank to be trimmed. To the knowledge of the authors, these are the first trimming simulations that can predict the effects of shearing clearance on burr heights with quantitative accuracy for AA6111-T4 aluminum sheets. In addition, the models have also accurately reproduced the crack initiation site as well as burr and sliver formation mechanisms observed experimentally.

Finite Element Analysis of Self-Piercing Riveting Process

2004 ◽  
Author(s):  
Bo Sui ◽  
Dong Du ◽  
Baohua Chang
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Sheet Material ◽  
Effective Strain ◽  
Element Model ◽  
Adaptive Meshing ◽  
Element Analysis ◽  
Plastic Properties ◽  
Aluminum Sheets ◽  
Riveting Process

A nonlinear finite element model is built to study the self-piercing riveting process. In this model, the elasto-plastic properties of sheets and rivet, i.e., the dependency of flow stress on effective strain is considered. The adaptive meshing technology is used for the separation of sheet material. The piercing operation on two 2 m m-thick 5754-O aluminum sheets is simulated, and the results obtained are in agreement with the published experimental results. Using this method, residual stress and strain are calculated under different die tip heights and rivet strengths, to obtain insights into the local mechanical behavior of the joints and the effect of process variables. It is found that the hoop residual stress is the main stress that affects the mechanical properties of joint. Higher riveting pressure is needed for higher die tip and higher rivet strength. Both the die tip height and river strength can affect the joint shape and residual stress.

Finite Element Modeling of Damage Formation in Rubber-Toughened Polymer

2005 ◽  
Vol 297-300 ◽  
pp. 1019-1024
Author(s):  
Mitsugu Todo ◽  
Yoshihiro Fukuya ◽  
Seiya Hagihara ◽  
Kazuo Arakawa
Keyword(s):  
Finite Element ◽  
Damage Zone ◽  
Damage Model ◽  
Crack Tip ◽  
Optical Microscope ◽  
Toughening Mechanism ◽  
Element Analysis ◽  
Zone Formation ◽  
Macro Scale ◽  
Rubber Toughened

Microscopic studies on the toughening mechanism of rubber-toughened PMMA (RTPMMA) were carried out using a polarizing optical microscope (POM) and a transmission electron microscope (TEM). POM result showed that in a typical RT-PMMA, a damage zone was developed in the vicinity of crack-tip, and therefore, it was considered that energy dissipation due to the damage zone development was the primary toughening mechanism. TEM result exhibited that the damage zone was a crowd of micro-crazes generated around rubber particles in the vicinity of notch-tip. Finite element analysis was then performed to simulate such damage formations in crack-tip region. Macro-scale and micro-scale models were developed to simulate damage zone formation and micro-crazing, respectively, with use of a damage model. It was shown that the damage model introduced was successfully applied to predict such kind of macro-damage and micro-craze formations.

Numerische Abbildung von Beton mit einem plastischen Schädigungsmodell – Grundlegende Untersuchungen zu Normalbeton und UHPC/Finite element simulation of concrete with a plastic damage model – Basic studies on normal strength concrete and UHPC

Bauingenieur ◽  
2015 ◽  
Vol 90 (06) ◽  
pp. 252-264 ◽  
Author(s):  
Dominik Kueres ◽  
Alexander Stark ◽  
Martin Herbrand ◽  
Martin Classen
Keyword(s):  
Finite Element ◽  
Finite Element Simulation ◽  
Damage Model ◽  
Normal Strength Concrete ◽  
Numerische Simulation ◽  
Plastic Damage ◽  
Element Simulation ◽  
Finite Elemente ◽  
Normal Strength ◽  
Basic Studies

Die numerische Simulation des Tragverhaltens von Beton- und Stahlbetonkonstruktionen mit nicht-linearen Finite-Elemente-Modellen gewinnt in der konstruktiven Ingenieurpraxis zunehmend an Bedeutung. In kommerziellen Finite-Elemente-Programmen stehen dem Anwender unterschiedliche Möglichkeiten zur Abbildung des Betonverhaltens in Form von plastischen Materialmodellen zur Verfügung. Zur Anwendung dieser Materialmodelle ist dabei in der Regel die Kenntnis des Betontragverhaltens unter einaxialer Druck- und Zugbeanspruchung erforderlich. Im vorliegenden Beitrag werden verschiedene Ansätze zur mathematischen Beschreibung dieser konstitutiven Beziehungen für Normalbeton und ultrahochfesten Beton (UHPC) vorgestellt und im Hinblick auf ihre Anwendbarkeit in plastischen Materialmodellen untersucht. Darauf aufbauend werden numerische Simulationen mit einem plastischen Schädigungsmodell unter Verwendung eines einheitlichen Parametersatzes durchgeführt und mit den Ergebnissen experimenteller Untersuchungen verglichen. Die Untersuchungen umfassen hierbei Materialprüfungen an Normalbeton und UHPC unter verschiedenen ein- und mehraxialen Spannungszuständen. Durch die Wahl geeigneter konstitutiver Beziehungen kann für die untersuchten Spannungszustände eine gute Übereinstimmung zwischen simuliertem und experimentell ermitteltem Betontragverhalten erreicht werden.

scholarly journals Gradient Nonlocal Enhanced Microprestress-Solidification Theory and Its Finite Element Implementation

2021 ◽  
Vol 8 ◽  
Author(s):  
Teng Tong ◽  
Changqing Du ◽  
Xiaofan Liu ◽  
Siqi Yuan ◽  
Zhao Liu
Keyword(s):  
Finite Element ◽  
Large Scale ◽  
Deformation Gradient ◽  
Damage Model ◽  
Reinforced Concrete Beams ◽  
Chain Model ◽  
Finite Element Software ◽  
Order Deformation ◽  
Implicit Solver

Time-dependent responses of cracked concrete structures are complex, due to the intertwined effects between creep, shrinkage, and cracking. There still lacks an effective numerical model to accurately predict their nonlinear long-term deflections. To this end, a computational framework is constructed, of which the aforementioned intertwined effects are properly treated. The model inherits merits of gradient-enhanced damage (GED) model and microprestress-solidification (MPS) theory. By incorporating higher order deformation gradient, the proposed GED-MPS model circumvents damage localization and mesh-sensitive problems encountered in classical continuum damage theory. Moreover, the model reflects creep and shrinkage of concrete with respect to underlying moisture transport and heat transfer. Residing on the Kelvin chain model, rate-type creep formulation works fully compatible with the gradient nonlocal damage model. 1-D illustration of the model reveals that the model could regularize mesh-sensitivity of nonlinear concrete creep affected by cracking. Furthermore, the model depicts long-term deflections and cracking evolutions of simply-supported reinforced concrete beams in an agreed manner. It is noteworthy that the gradient nonlocal enhanced microprestress-solidification theory is implemented in the general finite element software Abaqus/Standard with the implicit solver, which renders the model suitable for large-scale creep-sensitive structures.

scholarly journals COMPUTATION FOR THE DELAMINATION IN THE LAMINATE COMPOSITE MATERIAL USING A COHESIVE ZONE MODEL BY ABAQUS

2020 ◽  
Vol 57 (6A) ◽  
pp. 61
Author(s):  
Hoa Cong Vu
Keyword(s):  
Finite Element ◽  
Cohesive Zone Model ◽  
Constitutive Relations ◽  
Damage Zone ◽  
Damage Model ◽  
Zone Model ◽  
Element Formulation ◽  
Cohesive Elements ◽  
Element Mesh ◽  
Variable Mode

In this paper, a damage model using cohesive damage zone for the simulation of progressive delamination under variable mode is presented. The constitutive relations, based on liner softening law, are using for formulation of the delamination onset and propagation. The implementation of the cohesive elements is described, along with instructions on how to incorporate the elements into a finite element mesh. The model is implemented in a finite element formulation in ABAQUS. The numerical results given by the model are compare with experimental data

scholarly journals Modeling of Hydraulic Fracture of Concrete Gravity Dams by Stress-Seepage-Damage Coupling Model

2017 ◽  
Vol 2017 ◽  
pp. 1-15 ◽  
Author(s):  
Sha Sha ◽  
Guoxin Zhang
Keyword(s):  
Finite Element ◽  
Crack Propagation ◽  
Hydraulic Fracture ◽  
Carrying Capacity ◽  
Damage Model ◽  
Coupling Model ◽  
Propagation Path ◽  
Concrete Dams ◽  
Gravity Dams ◽  
Concrete Gravity Dams

High-pressure hydraulic fracture (HF) is an important part of the safety assessment of high concrete dams. A stress-seepage-damage coupling model based on the finite element method is presented and first applied in HF in concrete dams. The coupling model has the following characteristics: (1) the strain softening behavior of fracture process zone in concrete is considered; (2) the mesh-dependent hardening technique is adopted so that the fracture energy dissipation is not affected by the finite element mesh size; (3) four coupling processes during hydraulic fracture are considered. By the damage model, the crack propagation processes of a 1 : 40 scaled model dam and Koyna dam are simulated. The results are in agreement with experimental and other numerical results, indicating that the damage model can effectively predict the carrying capacity and the crack trajectory of concrete gravity dams. Subsequently, the crack propagation processes of Koyna dam using three notches of different initial lengths are simulated by the damage model and the coupling model. And the influence of HF on the crack propagation path and carrying capacity is studied. The results reveal that HF has a significant influence on the global response of the dam.

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