Ductile Failure Prediction of Spot Welded Lap Joint

2012 ◽  
Vol 165 ◽  
pp. 285-289 ◽  
Author(s):  
A.A. Borhana ◽  
A.T. Mohamad ◽  
A. Abdul-Latif ◽  
Z. Ahmad ◽  
A. Ayob ◽  
...  
Keyword(s):  
Finite Element ◽  
Stress Triaxiality ◽  
Ductile Failure ◽  
Material Damage ◽  
Fe Model ◽  
Lap Joint ◽  
Damage Initiation ◽  
Localized Necking ◽  
The Relationship ◽  
Spot Welded

A finite element (FE) model incorporating a progressive material damage with Rice-Tracey damage initiation criterion is developed in this study. The relationship between local ductility reduction and stress triaxiality was established experimentally. The FE model was validated by comparisons of load-displacement response of the spot welded lap joint specimen at displacement rate of 5 mm/min and the observed ductile failure mechanism. Results show that Rice-Tracey damage initiation criterion used is sufficient to reproduce the observed ductile failure response of the specimen. Failure of the spot welded lap joint is initiated at the HAZ/fusion zone interface with localized necking.

Failure mechanics analysis of AISI 4340 steel using finite element modeling of the milling process

2021 ◽  
pp. 030932472110580
Author(s):  
Muhammed Muaz ◽  
Sanan H Khan
Keyword(s):  
Finite Element ◽  
Failure Analysis ◽  
End Milling ◽  
Physical Phenomenon ◽  
Machining Process ◽  
Fe Model ◽  
Dissipation Energy ◽  
Damage Initiation ◽  
Milling Operation ◽  
Cutting Operation

A slot cutting operation is studied in this paper using a rotating/translating flat end milling insert. Milling operation usually comprises up-milling and down-milling processes. These two types of processes have different behaviors with opposite trends of the forces thus making the operation complex in nature. A detailed Finite Element (FE) model is proposed in this paper for the failure analysis of milling operation by incorporating damage initiation criterion followed by damage evolution mechanism. The FE model was validated with experimental results and good correlations were found between the two. The failure criteria field variable (JCCRT) was traced on the workpiece to observe the amount and rate of cutting during the machining process. It was found that the model was able to predict different failure energies that are dissipated during the machining operation which are finally shown to be balanced. It was also shown that the variation of these energies with the tool rotation angle was following the actual physical phenomenon that occurred during the cutting operation. Among all the energies, plastic dissipation energy was found to be the major contributor to the total energy of the system. A progressive failure analysis was further carried out to observe the nature of failure and the variation of stress components and temperature occurring during the machining process. The model proposed in this study will be useful for designers and engineers to plan their troubleshooting in various applications involving on-spot machining.

Material Ductile Failure-Based Finite Element Simulations of Chip Serration in Orthogonal Cutting of Titanium Alloy Ti-6Al-4V

2019 ◽  
Vol 141 (4) ◽  
Author(s):  
Guoliang Liu ◽  
Suril Shah ◽  
Tuğrul Özel
Keyword(s):  
Finite Element ◽  
Titanium Alloy ◽  
Orthogonal Cutting ◽  
Cutting Temperature ◽  
Cutting Speed ◽  
Ductile Failure ◽  
Ductile Deformation ◽  
Ductile Material ◽  
Damage Initiation ◽  
Coated Carbide

Titanium alloy Ti-6Al-4V, an alpha-beta alloy, possesses ductile deformation behavior and offers advantageous properties, light weight but high strength, good resilience, and resistance to corrosion, becoming highly suitable for aerospace and biomedical applications. However, its machinability is still considered a limiting factor in improving productivity. This paper presents a finite element modeling methodology for orthogonal cutting titanium alloy Ti-6Al-4V by considering material constitutive modeling together with material ductile failure in combination with damage initiation and cumulative damage-based evolution to simulate not only ductile material separation from workpiece to form chips but also chip serration mechanism by applying an elastic–viscoplastic formulation. The finite element model is further verified with orthogonal cutting experiments (using both uncoated and TiAlN-coated carbide tools) by comparing simulated and acquired forces and simulated and captured chip images at high cutting speeds. The effects of cutting speed, feed, tool rake angle, and tool coating on the degree of chip serration are studied through the simulation results. The cutting temperature and strain distributions are obtained to study the chip serration mechanism under different cutting conditions. It is confirmed that the material failure, crack initiation, and damage evolution are of great significance in the chip serration in cutting titanium alloy Ti-6Al-4V.

Finite Element Modeling of Laser Spot Welded Lap Joint

2008 ◽  
Vol 580-582 ◽  
pp. 291-294
Author(s):  
Zhi Guo Gao ◽  
Jian Huang ◽  
Yi Xiong Wu
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Aluminum Alloy ◽  
Finite Element Modeling ◽  
Spot Welding ◽  
Laser Spot ◽  
Lap Joint ◽  
Element Modeling ◽  
Laser Spot Welding ◽  
Spot Welded

For many years, rivet joint technology has been applied in the automotive and aerospace industry. Recently, it began to apply laser welding technology to lap joints instead of rivet joining. Laser spot welding has some potential advantages including time saving, cost reduction, material saving and weight reducing. A lap joint of aluminum alloy LY12 with different plate thickness, namely 2mm and 1mm, was spot-welded by CO2 laser. For the welding, laser power in pulse form with ramping-up and cooling-down shape was used, and pure helium gas served as shielding gas to fill around welding area. In this study transient three-dimensional non-linear finite element modeling was used to analyze heat flow and residual stress of the laser spot welding of aluminum alloy LY12. In modeling the temperature dependence of material properties, influence of contact surfaces are taken into account. To analyze, Gaussian distributed heat source model and thermo-elasto-plastic behavior were applied. Weld dimensions and residual stress at the weld surface were calculated numerically and compared with the experimental results.

Finite Element Simulation of Ductile Failure Process of Spot Welded Joint under Tensile Loading

2014 ◽  
Vol 660 ◽  
pp. 623-627
Author(s):  
Mohamad Shahrul Effendy Kosnan ◽  
Zaini Ahmad ◽  
Abdoulhdi Amhmad Borhana ◽  
Mohd Nasir Tamin
Keyword(s):  
Welded Joint ◽  
Fe Simulation ◽  
Tensile Deformation ◽  
Failure Process ◽  
Damage Model ◽  
Ductile Failure ◽  
Tensile Failure ◽  
Fe Model ◽  
Deformation And Failure ◽  
Spot Welded

Deformation response and failure process of a spot welded joint are investigated in this study. For this purpose, a cross-tension spot welded joint sample made of dual phase steel sheets (DP600) is prepared and tensile tested to failure. Complementary FE simulation of the test is performed. The FE model acknowledges the variation of properties across the spot welded region. Rice-Tracey ductile damage model is approximated and employed in the simulation. Close comparison of load-displacement curves and deformed shape with measured values serve as validation of the FE model. Results show that FE simulation with damage-based model adequately predicts tensile deformation and failure of the spot welded joint. Tensile failure of the joint is confined to the heat affected zone and heat affected/fusion zone interface of the joint. Localized through-thickness necking of the sheet metal is captured. In addition, the predicted fracture of the spot welded joint is accompanied by localized extensive plastic deformation.

scholarly journals Strength Based Numerical Approach Constitutive Material Prediction Of Spot Welded Joints Of Steel

KnE Energy ◽  
2016 ◽  
Vol 1 (1) ◽  
Author(s):  
I Nyoman Budiarsa
Keyword(s):  
Finite Element ◽  
Welded Joints ◽  
Plastic Material ◽  
Complex Structure ◽  
Complex Nature ◽  
Displacement Curve ◽  
Fe Model ◽  
Material Parameters ◽  
Constitutive Material ◽  
Spot Welded

<p>The deformation of spot welded joints is challenging research problem due to the complex nature of the structure. One major problem is to characterize the materials properties. The elastic-plastic material parameters and the fracture parameters of materials can be readily determined when standard specimens are available, however, for a spot welded joint, standard testing is not applicable to characterize the heat affected zone (HAZ) and the weld nugget due to their complex structure and small size. This has opened up the possibility to characterize the material properties based a dual indenter method to inversely characterize the parameters of the constitutive material laws for the nugget, HAZ and the base metals. In a mixed numerical-experimental approach, the load-deformation data of the material is used as input data to a finite element (FE) model that simulate the geometry and boundary conditions of the experiment.  With indentation tests, the local plastic properties can be calculated by solving the inverse problem via finite element analysis by incrementally varying properties in 3D modeling to find a similar simulated load–displacement curve as compared with experimental one. The approach will then be used to test different welding zones and the material parameters thus predicted used to simulate the deformation of spot welded joints under complex loading conditions including tensile shear and drop weight impact tests. The evaluation based on numerical experimental data showed similar accuracy to the continuous indentation curve approach.</p>

The Development of an Incrementally Loaded Finite Element Model of the Whole Skin Locomotion Mechanism: Discovering the Relationship Between Its Shape and Motion

2008 ◽  
Author(s):  
Derek Lahr ◽  
Dennis Hong
Keyword(s):  
Finite Element ◽  
Physical Mechanism ◽  
Element Model ◽  
Fe Model ◽  
Closed Volume ◽  
Robotic Platform ◽  
Biologically Inspired ◽  
The Relationship ◽  
Biologically Inspired Robot ◽  
Incremental Loading

The Whole Skin Locomotion (WSL) robotic platform is a novel biologically inspired robot that uses a fundamentally different locomotion strategy than other robots. Its motion is similar to the cytoplasmic streaming action seen in single celled organisms such as the amoeba. The robot is composed of a closed volume, fluid filled skin which generally takes the shape of an elongated torus. When in motion the outer skin is used as the traction surface. It is actuated by embedded smart material rings which undergo cyclical contractions and relaxations, generating an everting motion in the torroidially shaped skin. To better understand, design, and optimize this mechanism, it is necessary to have a model of the skin, fluid, and actuators and their interactions with the environment. This paper details the first steps in the development of a non-linear finite element (FE) model which will allow us to study these interactions and predict the shape and motion of the robot under various actuation strategies. A simple membrane element model is introduced from literature and is modified such that an incremental loading strategy can be employed. Finally, an underlying physical mechanism is introduced which could possibly describe the relationship between the shape of and pressure within the membrane skin and motion of the whole skin locomotion robot.

Predicting the Peen Forming Effectiveness of Ti-6Al-4V Strips With Different Thicknesses Using Realistic Finite Element Simulations

2015 ◽  
Vol 138 (1) ◽  
Author(s):  
Fan Yang ◽  
Yukui Gao
Keyword(s):  
Finite Element ◽  
Numerical Study ◽  
Residual Stress Distribution ◽  
Strip Thickness ◽  
Thin Strip ◽  
Fe Model ◽  
Rate Dependent ◽  
Peen Forming ◽  
Proposed Model ◽  
The Relationship

This paper is intended to quantify the relationship between the peen forming effectiveness and various involved parameters through a realistic numerical study. For this purpose, a new finite element (FE) model is proposed with full geometry representation, random shots generation, and rate-dependent material law of kinematic strain-hardening. The mesh sensitivity and effects of boundary conditions are carefully examined. The FE model is validated by comparing the results with the experimental measurements. The proposed model is then used to investigate the effects of the peening intensity (represented as the shot velocity) and the strip thickness on the peen-formed deflection and the residual stress distribution for strips made of Ti-6Al-4V. Our results indicate the existence of a maximum convex deflection for different strip thicknesses. In addition, a reversed deflection (i.e., concaved curvature) is observed for severe peening conditions (i.e., thin strip under high peening intensity). Our simulations verify the previous proposition that a concaved curvature can be generated only when the whole cross section is plastically deformed.

Damage Analysis of Glass-to-Metal Diffusion Welded Joints

2008 ◽  
Vol 44-46 ◽  
pp. 765-772 ◽  
Author(s):  
Xi Hai Shen ◽  
Xiang Ling
Keyword(s):  
Finite Element ◽  
Welded Joints ◽  
Thermal Power ◽  
Electronic Devices ◽  
Fem Analysis ◽  
Lap Joints ◽  
Diffusion Welding ◽  
Fe Model ◽  
Damage Initiation ◽  
Metal Diffusion

The glass-to-metal seals are usually used in the solar thermal power (STP) and electronic devices. However, the requirement of mechanical properties in the STP is much higher than that of electronic devices, because the glass-to-metal joints used in the STP need to have anti-fatigue performance in adition to higher static tensile strength. Under the repeated fluctuating loads, damage and failures of glass-to-metal seals in the STP often lead to serious consequences. Therefore, analysis of damage evolution and fracture behavior of glass-to-metal diffusion welded joints was performed in this paper. Firstly, the finite element (FE) model of glass-to-metal welded joints was established in accordance with the STP welded structures. And damage simulation was carried out by the FE software ABAQUS. Also, the work illustrates the modeling of damage in terms of traction versus separation to simulate crack propagation and introduces the use of traction-separation law as a damage initiation and evolution criteria. The microgram of damage distribution in the glass side near the interface could be characterized by Scanning Electron Microscope (SEM), which was compared with predictions obtained by finite element method (FEM) analysis. As result, the damage criteria on the lap joints in conjunction with FM analysis were used to optimize the glass-to-metal diffusion welding technology. The above results provide the basis of design against damage and reliable estimation of glass-to-metal seals.

scholarly journals Compaction density variation in powder metallurgy components

2021 ◽  
Author(s):  
Elham Jafar-Salehi
Keyword(s):  
Finite Element ◽  
Powder Metallurgy ◽  
Density Distribution ◽  
Relative Density ◽  
Compaction Pressure ◽  
Density Variation ◽  
Fe Model ◽  
Green Density ◽  
Artificial Neural Network Ann ◽  
The Relationship

The main objective of this research was to study the relationship between green density and compaction pressure in powdered metallurgy. Powder metallurgy has gained popularity and importance because of its near net shape, cost effectiveness and its ability to reduce the complexity of multileveled engineering components. However, powder metallurgy poses challenges that are yet to be fully understood. There are many works performed to address challenges such as the effect of friction, the tool kinematics, handling component prior to sintering and fracture under compaction. This work concentrates on the relationship between green density distribution and compaction pressure. In order to measure the relative density of compacted components, Electron Scanning Microscope was utilized. One can intuitively conceive that the relative density requires more than intuition. It was determined that highest relative density occurs at the center of the specimen and reduces toward the die-powder or punch-powder boundary. For completeness, the application of artificial neural network (ANN) and finite element (FE) model in estimation of green relative density was studied. The results of this research signify that ANN is an excellent technique to determine the relative density distribution of un-sintered compacted specimen. Moreover, finite element method can accurately estimate the average relative density of compacted specimen.

scholarly journals Impact Behaviour of Spot-Welded Thin-Walled Frusta

2016 ◽  
Vol 10 (4) ◽  
pp. 280-284
Author(s):  
Maria Kotełko ◽  
Artur Mołdawa
Keyword(s):  
Finite Element ◽  
Dynamic Response ◽  
Energy Absorption ◽  
Parametric Study ◽  
Impact Load ◽  
Initial Study ◽  
Fe Model ◽  
Dynamic Impact ◽  
Thin Walled ◽  
Spot Welded

Abstract In the paper the dynamic response of thin-walled, spot-welded prismatic frusta subjected to axial impact load is investigated. The parametric study into the influence of several parameters on the energy absorption capability, expressed by some crashworthiness indicators is performed, using Finite Element simulations. FE model is validated by experimental results of quasi-static and dynamic (impact) tests. Results of initial study concerning influence of spot welds are presented. Some conclusions are derived from the parametric study into the influence of frustum angle and wall thickness upon the energy absorption capability.

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