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>

Representation of bolted joints in a structure using finite element modelling and model updating

2020 ◽  
Vol 14 (3) ◽  
pp. 7141-7151 ◽  
Author(s):  
R. Omar ◽  
M. N. Abdul Rani ◽  
M. A. Yunus
Keyword(s):  
Finite Element ◽  
Dynamic Behaviour ◽  
Model Updating ◽  
Complex Structure ◽  
Bolted Joints ◽  
Model Parameters ◽  
Fe Model ◽  
Bolted Joint ◽  
Fe Modelling ◽  
Joint Structure

Efficient and accurate finite element (FE) modelling of bolted joints is essential for increasing confidence in the investigation of structural vibrations. However, modelling of bolted joints for the investigation is often found to be very challenging. This paper proposes an appropriate FE representation of bolted joints for the prediction of the dynamic behaviour of a bolted joint structure. Two different FE models of the bolted joint structure with two different FE element connectors, which are CBEAM and CBUSH, representing the bolted joints are developed. Modal updating is used to correlate the two FE models with the experimental model. The dynamic behaviour of the two FE models is compared with experimental modal analysis to evaluate and determine the most appropriate FE model of the bolted joint structure. The comparison reveals that the CBUSH element connectors based FE model has a greater capability in representing the bolted joints with 86 percent accuracy and greater efficiency in updating the model parameters. The proposed modelling technique will be useful in the modelling of a complex structure with a large number of bolted joints.

scholarly journals Use of 3D Scan of Weld Joint in Finite Element Analysis and Stochastic Analysis of Hot-Spot Stresses in Tubular Joint for Fatigue Life Estimation

2019 ◽  
Author(s):  
Mikkel L. Larsen ◽  
Vikas Arora ◽  
Marie Lützen ◽  
Ronnie R. Pedersen ◽  
Eric Putnam
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Welded Joints ◽  
Hot Spot ◽  
Strain Range ◽  
Fe Model ◽  
Design Codes ◽  
Element Analysis ◽  
Hot Spot Stress ◽  
Weld Toe

Abstract Several methods for modelling and finite element analysis of tubular welded joints are described in various design codes. These codes provide specific recommendations for modelling of the welded joints, using simple weld geometries. In this paper, experimental hot-spot strain range results from a full-scale automatically welded K-node test are compared to corresponding finite element models. As part of investigating the automatically welded K-joint, 3D scans of the weld surfaces have been made. These scans are included in the FE models to determine the accuracy of the FE models. The results are compared to an FE model with a simple weld geometry based on common offshore design codes and a model without any modelled weld. The results show that the FE model with 3D scanned welds is more accurate than the two simple FE models. As the weld toe location of the 3D scanned weld is difficult to locate precisely in the FE model and as misplacement of strain gauges are possible, stochastic finite element modelling is performed to analyse the resulting probabilistic hot-spot stresses. The results show large standard deviations, showing the necessity to evaluate the hot-spot stress method when using 3D scanned welds.

Calculation method of belt material parameters for finite element tire model

2021 ◽  
pp. 095440702110422
Author(s):  
Lu Zhang ◽  
Shaohua Wang ◽  
Bing Li
Keyword(s):  
Finite Element ◽  
Calculation Method ◽  
Complex Structure ◽  
Three Dimensional ◽  
Anisotropic Elasticity ◽  
Dynamic Responses ◽  
Reinforced Composites ◽  
Tire Model ◽  
Material Parameters ◽  
Vehicle Dynamic Simulation

The radial tire belt is composed of multi-layered fiber-reinforced cords with a very complex structure. Restricted by the computing speed, the simplified finite element (FE) tire model with equivalent belt is usually applied in the vehicle dynamic simulation. However, it is always difficult to obtain the material parameters of the equivalent belt. In this paper, a calculation method of equivalent belt material parameters for the simplified FE tire model is proposed based on the three-dimensional (3-D) anisotropic elasticity of the cord reinforced composites. The simulation results of the static radial stiffness, modal characteristics, and dynamic responses for the simplified FE tire model with parameters obtained by the calculation method were compared with experiment results. The results show that the deviation between the experiment and simulation is acceptable, and the validity of the calculation method is verified.

THE INFLUENCE OF BRAIN TISSUE MATERIAL PARAMETERS ON THE RESPONSE OF DYNAMIC CHARACTERISTICS BASED ON FINITE ELEMENT MODEL

2019 ◽  
Vol 19 (08) ◽  
pp. 1940058
Author(s):  
BIN YANG ◽  
HAO SUN ◽  
AIYUAN WANG ◽  
QUN WANG
Keyword(s):  
Finite Element ◽  
Head And Neck ◽  
Brain Tissue ◽  
Dynamic Characteristics ◽  
Human Head ◽  
Initial Parameter ◽  
Fe Model ◽  
Nasal Cartilage ◽  
Material Parameters ◽  
Tissue Material

Aiming at the uncertainty of material parameters of human brain tissue, the influence of tissue material performance sensitivity on frequency and mode shape under free vibration is studied. In this paper, the 50th percentile finite element (FE) model of human head and neck with detailed anatomical characteristics has been chosen as the research object, the parameters of skull, cerebrospinal fluid (CSF) and brain tissue materials with high sensitivity are analyzed by orthogonal test design and variance analysis. The results show that the natural frequencies of Group 7, Group 8 and Group 9 are all around 230[Formula: see text]Hz, which are basically consistent with the initial parameter of 229.18[Formula: see text]Hz, and the intracranial displacements of the three groups are also concentrated on the lateral nasal cartilage. The main reason is that the Young’s modulus of the skull used in three groups of experiments is 9780[Formula: see text]Mpa, which is close to the initial parameter of 8000[Formula: see text]Mpa. It indicates that the material parameter of the skull has the greatest influence on the dynamic characteristics of human head and neck, followed by the CSF and brain tissue. This study provides an effective method for vehicle safety and head and neck injury protection, and supplies a reference for FE analysis of head collision damage.

Fatigue Damage of Aluminum Alloy Spot-Welded Joint Based on Defects Reconstruction

2019 ◽  
Vol 142 (2) ◽  
Author(s):  
Sha Xu ◽  
Hao Chen ◽  
Yali Yang ◽  
Kun Gao
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Aluminum Alloy ◽  
Elastic Modulus ◽  
3D Reconstruction ◽  
Fatigue Damage ◽  
Welded Joints ◽  
Effective Elastic Modulus ◽  
X Ray ◽  
Spot Welded

Abstract Three-dimensional (3D) reconstruction and finite element method are combined to study the damage behavior of aluminum alloy resistance spot-welded joints. Fatigue damage of spot-welded joints under different cyclic loading stages was obtained by X-ray microcomputed tomography (X-ray micro CT). Then, avizo software was used to reconstruct the scanned data of joints with different damage degrees, and the distribution and variation of defects in the joints are obtained. On this basis, 3D finite element damage models were established. Finite element calculations were carried out to analyze the fatigue damage of spot-welded joints by adopting the effective elastic modulus as the damage parameter. The results show that the effective elastic modulus is consistent with the experimental results. The method of combining 3D reconstruction with the finite element method can be used to evaluate the internal damage of spot-welded joints and provide theoretical basis for the prediction of fatigue life.

Effect of Initial Gap on Tensile Strength of Resistance Spot Welded Joints

2010 ◽  
Vol 154-155 ◽  
pp. 325-328
Author(s):  
Hai Jun Yang ◽  
Yan Song Zhang ◽  
Jie Shen ◽  
Xin Min Lai
Keyword(s):  
Tensile Strength ◽  
Shear Strength ◽  
Welded Joints ◽  
Fe Model ◽  
Tensile Shear Strength ◽  
Tensile Shear ◽  
Resistance Spot ◽  
Nugget Formation ◽  
Spot Welded

It has been proved that the initial gap has obvious influence on nugget formation, but little works focused on the effect of initial gap on the tensile strength of resistance spot welded (RSW) joints. In this paper, a 3D FE model was built for solving this question. The results show that, even though there are some fluctuations of weld diameter and tensile strength of RSW joints with initial gap, the tensile strength and weld diameter of welded joints with initial gap are still larger than that of welded joints without gap, which confirm that the influence of initial gap on tensile shear strength is little significant. The computation results agree well with experiment.

Influence of Strength Level of Steels on Fatigue Strength and Fracture Morphology of Spot Welded Joints

2011 ◽  
Vol 462-463 ◽  
pp. 94-99
Author(s):  
Keiichiro Tohgo ◽  
Tomoya Ohguma ◽  
Yoshinobu Shimamura ◽  
Yoshifumi Ojima
Keyword(s):  
Finite Element ◽  
Fatigue Strength ◽  
Mild Steel ◽  
Welded Joints ◽  
High Strength ◽  
Fracture Morphology ◽  
Fatigue Tests ◽  
Finite Element Analyses ◽  
Ultra High Strength Steel ◽  
Spot Welded

In this paper, fatigue tests and finite element analyses are carried out on spot welded joints of mild steel (270MPa class) and ultra-high strength steel (980MPa class) in order to investigate the influence of strength level of base steels on fatigue strength and fracture morphology of spot welded joints. From the fatigue tests the following results are obtained: (1) Fatigue limit of spot welded joints is almost the same in both steels. (2) Fatigue fracture morphology of spot welded joints depends on the load level in the ultra-high strength steel, but not in the mild steel. From discussion based on the finite element analyses the following results are obtained: (3) The fatigue limit of spot welded joints can be predicted by stress intensity factors for a nugget edge, fracture criterion for a mixed mode crack and threshold value for fatigue crack growth in base steel. (4) Plastic deformation around a nugget in spot welded joints strongly affects the fatigue fracture morphology.

Automated Segmentation of Swine Skulls for Finite Element Model Creation Using High Resolution μ-CT Images

2019 ◽  
Vol 16 (03) ◽  
pp. 1842012 ◽  
Author(s):  
Zimo Zhu ◽  
Donna C. Jones ◽  
G. R. Liu ◽  
Sajjad Soleimani ◽  
Xu Huang ◽  
...  
Keyword(s):  
Finite Element ◽  
Material Properties ◽  
Complex Structure ◽  
Model Development ◽  
Element Model ◽  
Fe Model ◽  
Micro Computed Tomography ◽  
Mineral Density ◽  
Detailed Model ◽  
Bone Mineral Density Loss

Finite element (FE) analysis has been widely used to investigate bone responses to mechanical loading. Research in long bones has been straight forward because modeling of these bones requires only two material properties. Such an FE model may provide an adequate approximation of the anatomy for many cases. However, a more detailed model of skull bones is needed to accurately capture its complex structure of multiple bone pieces and the various mineral densities distributed throughout these bone pieces. Unfortunately, FE model development incorporating both complex geometries and anatomically accurate material properties is both computationally and labor intensive. In this study, a method is proposed to automatically segment micro-computed tomography ([Formula: see text]-CT) scan images of bone pieces to build an FE model of a full swine hemi-skull. Using the Digital Imaging and Communications in Medicine (DICOM) files from scanned bones, the complete geometry of each bone piece is recreated through seven customized processing algorithms. After assembling the bone pieces to form the skull, experimentally derived Young’s modulus values are correlated to grayscale values to produce a detailed FE model for accurate simulation. This detailed skull model can be used to predict strain/stress patterns in response to various loading regimes to facilitate research questions in fracture healing and growth, as well as bone tissue engineering and bone mineral density loss (e.g., osteoporosis).

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