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 Matching Performance on J-Integral of Inhomogeneous Welded Joints

2012 ◽  
Vol 503-504 ◽  
pp. 568-571
Author(s):  
Bo He ◽  
Hong Cai Zhang
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Elastic Modulus ◽  
Yield Strength ◽  
Engineering Design ◽  
Welded Joints ◽  
Welded Joint ◽  
J Integral ◽  
The Finite Element Method ◽  
Matching Performance

In this paper, J-integral of 3-zone inhomogeneous welded joint is calculated by use of the finite element method, and the impacts of yield strength matching factor and elastic modulus matching factor on J-integral are studied as well. The analysis results show that the yield strength matching factor affects J-integral value greatly, that is, low matching of inhomogeneous welded joint of same steel can help to improve the ductility of the welded joint and the influence of yield strength matching factor on J-integral is much greater than that of elastic modulus matching factor, so it plays a very important role in the engineering design.

Effect of Fiber Waviness and Cluster on Effective Elastic Properties of Fiber-Reinforced Composites

2015 ◽  
Author(s):  
Bincheng Huang ◽  
Lingyu Sun ◽  
Ligang Wang ◽  
Tongguang Li
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Elastic Modulus ◽  
Volume Fraction ◽  
Effective Elastic Modulus ◽  
Fiber Reinforced Polymers ◽  
Fiber Reinforced ◽  
Fiber Waviness ◽  
Bridging Model ◽  
Element Method

Carbon fiber-reinforced polymers (CFRPs) are widely applied in lightweight automotive design due to their high specific stiffness and strength. However, it is difficult to achieve an ideal performance due to defects from manufacturing process. For example, fiber waviness and cluster are two typical manufacture defects in the process of Liquid Composite Molding (LCM). The effective elastic modulus of CFRPs with fiber waviness is studied by finite element method, and the stress-transfer mechanisms between the fibers and matrix is explained theoretically, the modified bridging model, which correlates the stress state in fibers with that in matrix. Additionally, the influence of fiber cluster on the effective elastic modulus of CFRPs is also investigated by finite element method. When the volume fraction of fibers in matrix is higher than 20%, the fiber waviness will decrease the longitudinal modulus E11 greatly, but also increase the transverse modulus E22 slightly. For CFRPs with cured fibers, the proposed modified bridging model has higher prediction accuracy than the rule of mixture. When the cluster degree is less than 1%, the effective elastic modulus of CFRPs with fibers distributed randomly will not be influenced obviously. For straight fibers, the reinforcement effect on elastic modulus E11 and shear modulus G12 decreases slightly with increasing cluster degree.

The Study on Crashworthiness Performance of Thin-Walled Structures and the Effect of Welding Performance on it

2011 ◽  
Vol 63-64 ◽  
pp. 655-658
Author(s):  
Qi Hao ◽  
Sheng Jun Wu
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Welded Joints ◽  
Impact Force ◽  
Deformation Energy ◽  
Optimal Shape ◽  
Explicit Finite Element Method ◽  
Explicit Finite Element ◽  
Thin Walled Structures ◽  
Thin Walled

Explicit finite element method is adopted to simulate the crashworthiness performance of four types of typical thin—walled structures used in vehicle by software LS-DYNA. The structures with the same material、area and length are crash by a rigid body with 40km/h in10ms, The crash processes and crashworthiness characters are analyzed by a series crash parameters: deformation energy with unit displacement, impact force and deceleration to look for the optimal shape with crashworthiness. With comparing, the double caps section has ascendant performance than the others. The simulating methods of welded-joints are discussed to analysis their effects on crashworthiness simulation.

Microstructure and morphology evolution of probeless friction stir spot welded joints of aluminum alloy

2018 ◽  
Vol 252 ◽  
pp. 69-80 ◽  
Author(s):  
W.Y. Li ◽  
Q. Chu ◽  
X.W. Yang ◽  
J.J. Shen ◽  
A. Vairis ◽  
...  
Keyword(s):  
Aluminum Alloy ◽  
Welded Joints ◽  
Morphology Evolution ◽  
Friction Stir ◽  
Spot Welded

Fatigue damage in bending of reinforced concrete frames using non-destructive tests for dynamic strength of the cylinder

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Dragan D. Milašinović ◽  
Aleksandar Landović ◽  
Danica Goleš
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Fatigue Damage ◽  
Cross Section ◽  
Modal Parameters ◽  
The Finite Element Method ◽  
Concrete Frames ◽  
Content Type ◽  
Non Destructive

PurposeThe purpose of this paper is to contribute to the solution of the fatigue damage problem of reinforced concrete frames in bending.Design/methodology/approachThe problem of fatigue damage is formulated based on the rheological–dynamical analogy, including a scalar damage variable to address the reduction of stiffness in strain softening. The modal analysis is used by the finite element method for the determination of modal parameters and resonance stability of the selected frame cross-section. The objectivity of the presented method is verified by numerical examples, predicting the ductility in bending of the frame whose basic mechanical properties were obtained by non-destructive testing systems.FindingsThe modal analysis in the frame of the finite element method is suitable for the determination of modal parameters and resonance stability of the selected frame cross-section. It is recommended that the modulus of elasticity be determined by non-destructive methods, e.g. from the acoustic response.Originality/valueThe paper presents a novel method of solving the ductility in bending taking into account both the creep coefficient and the aging coefficient. The rheological-dynamical analogy (RDA) method uses the resonant method to find material properties. The characterization of the structural damping via the damping ratio is original and effective.

scholarly journals Integrating the Finite Element Method with a Data-Driven Approach for Dam Displacement Prediction

2020 ◽  
Vol 2020 ◽  
pp. 1-16 ◽  
Author(s):  
Chenfei Shao ◽  
Chongshi Gu ◽  
Zhenzhu Meng ◽  
Yating Hu
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Elastic Modulus ◽  
Random Coefficient ◽  
Arch Dam ◽  
Data Driven ◽  
The Finite Element Method ◽  
Random Coefficient Model ◽  
Proposed Model ◽  
Element Method

Both numerical simulations and data-driven methods have been applied in dam’s displacement modeling. For monitored displacement data-driven methods, the physical mechanism and structural correlations were rarely discussed. In order to take the spatial and temporal correlations among all monitoring points into account, we took the first step toward integrating the finite element method into a data-driven model. As the data-driven method, we selected the random coefficient model, which can make each explanatory variable coefficient of all monitoring points following one or several normal distributions. In this way, explanatory variables are constrained. Another contribution of the proposed model is that the actual elastic modulus at each monitoring point can be back-calculated. Moreover, with a Lagrange polynomial interpolation, we can obtain the distribution field of elastic modulus, rather than gaining one value for the whole dam in previous studies. The proposed model was validated by a case study of the concrete arch dam in Jinping-I hydropower station. It has a better prediction precision than the random coefficient model without the finite element method.

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