scholarly journals Effects of residual stress on the stability of multi-welded integral stiffened panels

2021 ◽  
Vol 39 (3) ◽  
pp. 586-592
Author(s):  
Yanning Guo ◽  
Yu'e Ma ◽  
Wenbo Sun ◽  
Yong Xue ◽  
Chunwei Kuang
Keyword(s):  
Residual Stress ◽  
Great Influence ◽  
Stiffened Panel ◽  
Stiffened Panels ◽  
Mechanical Coupling ◽  
Friction Stir ◽  
Welding Sequence ◽  
Post Buckling ◽  
The Stability ◽  
The Right

In order to clarify the influence of residual stress on the stability of 2024-T3 friction stir welded(FSWed) integral stiffened panels with multi-welds, the ANSYS software was used to establish the finite element models of two typical multi-FSWed stiffened panels. The residual stresses of two typical multi-welded stiffened panels (Panel A and Panel B) were calculated respectively using the thermal-mechanical coupling method. And the buckling and post-buckling responses of the stiffened plates were analyzed. It is shown that the residual stress distribution of stiffened panel was affected by the welding sequence. The maximum residual stress of Panel A mainly appears on the right side of the stringer, and that of Panel B appears on the stringer that is welded later. The residual stress has a great influence on the stability of the welded stiffened panels. When the residual stress profiles are taken into consideration, the critical buckling loads of welded Panel A and Panel B will decrease 14.2% and 12.4% respectively.

scholarly journals Stability Analysis of Different Stiffened Plates in Thermal-Mechanical Coupling Environments

2020 ◽  
Vol 38 (1) ◽  
pp. 40-47
Author(s):  
Liang Ma ◽  
Yu'e Ma ◽  
Qiang Qin
Keyword(s):  
Mechanical Load ◽  
Maximum Load ◽  
Stiffened Panel ◽  
Stiffened Plate ◽  
Stiffened Panels ◽  
Mechanical Coupling ◽  
Cross Section Area ◽  
Out Of Plane ◽  
Post Buckling ◽  
Plane Displacement

In view of the structural stability problem of different typical stiffened panels under different loading conditions, ABAQUS software was used to build finite element models of four typical stiffened panels with the same cross section area. The buckling and post-buckling response of the stiffened panels was analyzed and buckling modes and deflection curves of stiffened panels under mechanical, temperature and thermal-mechanical coupling load were obtained. The result indicates that T type stiffened plate shows great stability under mechanical load, the maximum load is 281KN, which is much higher than that of other types of stiffened panels. The maximum load of a stiffened panel is little affected by the direction of the fillet, but reasonable layout of panels can greatly reduce the out-of-plane displacement of the stiffened panel. There is no obvious pre-buckling process when a panel is under thermal-mechanical coupling load and the post-buckling response is roughly similar as that under mechanical load. But the maximum load of a stiffened plate will decrease by 8%-15% due to the application of temperature load.

Numerical Simulation for Residual Stress and Deformation of Surface Welding on Membrane Water-Wall

2014 ◽  
Vol 490-491 ◽  
pp. 594-599
Author(s):  
Fan Ling Meng ◽  
Ai Guo Liu
Keyword(s):  
Residual Stress ◽  
Great Influence ◽  
Residual Deformation ◽  
Welding Residual Stress ◽  
Finite Element Software ◽  
Welding Sequence ◽  
Surface Welding ◽  
Stress And Deformation ◽  
Welding Sequences ◽  
Residual Stress And Deformation

Automatic MIG was adopted to weld Inconel 625 alloy on 20 G Membrane Waterwall, which can improve the capacities of high temperature corrosion resistance and wear resistance. To study the influence of Membrane Waterwall surface welding sequences on residual stress and residual deformation, this paper utilized finite element software ABAQUS and segmented moving heat source model to simulate the sequence welding, balanced welding from the middle to sides, balanced welding from sides to the middle, balanced skip welding from middle to sides and balanced skip welding from sides to the middle and studied their residual stresses and deformations. The simulation results indicated that there was a great influence of welding sequences on the residual stress and deformation. The optimal welding sequence was balanced skip welding from middle to sides and balanced skip welding from sides to the middle, which could change the stress distribution, decrease the welding residual stress by 17%, realize the even deformation of the whole welding section and decrease the bending deformation by 50%.

scholarly journals Buckling/post-buckling strength of friction stir welded aircraft stiffened panels

2012 ◽  
Vol 228 (2) ◽  
pp. 178-192 ◽  
Author(s):  
A Murphy ◽  
T Ekmekyapar ◽  
M Özakça ◽  
K Poston ◽  
G Moore ◽  
...  
Keyword(s):  
Stiffened Panels ◽  
Buckling Strength ◽  
Friction Stir ◽  
Post Buckling

Influence of Welding Sequence on Residual Stress and Distortion in Rectangular Welding of 6061 Aluminum Alloy

2013 ◽  
Vol 668 ◽  
pp. 890-897
Author(s):  
Yi Jie ◽  
Li Can ◽  
Zhong Gang Sun
Keyword(s):  
Residual Stress ◽  
Aluminum Alloy ◽  
6061 Aluminum Alloy ◽  
Element Simulation ◽  
Welding Sequence ◽  
Maximum Residual Stress ◽  
Comparison And Analysis ◽  
Thin Walled ◽  
The Stability ◽  
Coupling Algorithm

This paper presented a detailed finite element simulation on the basis of elastic-plastic method combined with thermo-mechannical coupling algorithm，and the software abaqus was used for the welding simulation of thin-walled 6061-T6 aluminum. The residual stress and distortion with various types of welding sequence were investigated and the optimal welding sequence was gained through comparison and analysis. The results showed that the maximum residual stress on the plane of the welds was tensile stress after welding in a rectangular. The method of symmetry welding got smaller residual stress which could enhance the stability of the weldments, and starting from a longer welding path got smaller residual distortion of aluminum alloy.

Experimental and Numerical Study on Six- Point Bending Test of a Composite Stiffened Panel

2011 ◽  
Vol 328-330 ◽  
pp. 1309-1312
Author(s):  
Qiang Ye ◽  
San San Xiao ◽  
Pu Hui Chen
Keyword(s):  
Cohesive Zone Model ◽  
Numerical Study ◽  
Bending Test ◽  
Stiffened Panel ◽  
Zone Model ◽  
Buckling Mode ◽  
Stiffened Panels ◽  
Shell Elements ◽  
Composite Stiffened Panel ◽  
Post Buckling

A six-point bending test was presented to simulate skin/stiffener debonding under anti-symmetrical loading conditions. A novel rig was design via which the anti-symmetrical bending deformations can be forced on to the specimens. Experimental study on six-point bending test of composite stiffened panels of T700/QY8911 was done by using this rig. The tests are numerically analyzed using the finite element code ABAQUS, modeling the entire stiffened panel by shell elements, and investigating the progressive delamination by means of the cohesive zone model. The results of numerical analyses are compared to the experimental ones in terms of load-displacement curves and debonding positions between skin and stringer. The experimental and numerical resulits show that the anti-symmetrical bending deformation is the main factor which results in the asymmetrical propagation of the debonding between the skin and the stiffener. The failure mechanisms of the test are similar to the ones which induces skin/stiffener debonding during post-buckling in the anti-symmetrical buckling mode.

Integrated Design and Numerical Simulation of Stiffened Panels Including Friction Stir Welding Effects

2013 ◽  
Vol 554-557 ◽  
pp. 2237-2242 ◽  
Author(s):  
Rui Miguel Ferreira Paulo ◽  
Pierpaolo Carlone ◽  
Robertt A.F. Valente ◽  
Filipe Teixeira-Dias ◽  
Gaetano S. Palazzo
Keyword(s):  
Numerical Simulation ◽  
Residual Stress ◽  
Friction Stir Welding ◽  
Stress Distribution ◽  
Residual Stresses ◽  
Ultimate Load ◽  
Simulation Models ◽  
Residual Stress Distribution ◽  
Stiffened Panels ◽  
Friction Stir

Stiffened panels are usually the basic structural building blocks of airplanes, vessels and other structures with high requirements of strength-to-weight ratio. They typically consist of a plate with equally spaced longitudinal stiffeners on one side, often with intermediate transverse stiffeners. Large aeronautical and naval parts are primarily designed based on their longitudinal compressive strength. The structural stability of such thin-walled structures, when subjected to compressive loads, is highly dependent on the buckling strength of the structure as a whole and of each structural member. In the present work, a number of modelling and numerical calculations, based on the Finite Element Method (FEM), is carried out in order to predict the ultimate load level when stiffened panels are subjected to compressive solicitations. The simulation models account not only for the elasto-plastic nonlinear behaviour, but also for the residual stresses, material properties modifications and geometrical distortions that arise from Friction Stir Welding (FSW) operations. To construct the model considering residual stresses, their distribution in FSW butt joints are obtained by means of a numerical-experimental procedure, namely the contour method, which allows for the evaluation of the normal residual stress distribution on a specimen section. FSW samples have been sectioned orthogonally to the welding line by wire electrical discharge machining (WEDM). Displacements of the relaxed surfaces are then recorded using a Coordinate Measuring Machine and processed in a MATLAB environment. Finally, the residual stress distribution is evaluated by means of an elastic FE model of the cut sample, using the measured and digitalized out-of-plane displacements as input nodal boundary conditions. With these considerations, the main goal of the present work will then be related to the evaluation of the effect of FSW operations, in the ultimate load of stiffened panels with complex cross-section shapes, by means of realist numerical simulation models.

Optimization of lightweight sub-stiffened panels with buckling analysis and imperfection sensitivity analysis

2019 ◽  
Vol 233 (15) ◽  
pp. 5507-5521 ◽  
Author(s):  
Hao Chen ◽  
Yuanming Xu ◽  
Junhao Hu ◽  
Xi Wang
Keyword(s):  
Sensitivity Analysis ◽  
Ultimate Strength ◽  
Multidisciplinary Optimization ◽  
Uniaxial Loading ◽  
Stiffened Panel ◽  
Imperfection Sensitivity ◽  
Engineering Structures ◽  
Buckling Loads ◽  
Stiffened Panels ◽  
Post Buckling

On the purpose of improving the structural efficiency of stiffened panels, which is widely used in engineering, three promising layouts of sub-stiffened thin-walled structures were optimized in view of structure's initial buckling and further analyzed through post-buckling and imperfection-sensitivity analysis. The optimization tasks were carried out using an integrated framework, which is based on the multidisciplinary optimization platform Model Center and finite element method software ABAQUS. The particle swarm optimization algorithm was applied to optimize layout parameters. Three optimal sub-stiffened panels were then evaluated based on their performance on critical buckling loads and post-buckling ultimate strength under uniaxial loading. Imperfection-sensitivity analysis was also conducted to investigate the stability behavior of the proposed panels with defect. The results indicate that the introduction of sub-stiffeners into the traditional stiffened panel can achieve significant improvements on the panel's buckling loads and ultimate strength under uniaxial loading, which are favorable to expand design space for engineering structures under requirements of lightweight with high bending stiffness and bucking resistance.

On the Stability of Discrete Models of Compressed Beams in Elastic Media

2012 ◽  
Vol 152-154 ◽  
pp. 982-989 ◽  
Author(s):  
Fabio de Angelis
Keyword(s):  
Elastic Medium ◽  
Great Influence ◽  
Elastic Stiffness ◽  
Discrete Models ◽  
Elastic Media ◽  
Structural System ◽  
Equilibrium Configurations ◽  
Overall Stability ◽  
Post Buckling ◽  
The Stability

The equilibrium configurations of compressed elastic beams in an elastic medium are investigated. The analysis is performed on discrete models by means of a geometric non linear treatment. The effect of the elastic stiffness of the medium on the overall stability of the structural system is taken into account through a parameter which represents the ratio between the elastic medium stiffness and the beam stiffness. This parameter shows to have a great influence on the buckling and post-buckling behaviour of the structure.

Reliability Analysis of Buckling Limit State for Friction Stir Welded Aircraft Stiffened Panels

2015 ◽  
Vol 640 ◽  
pp. 35-42 ◽  
Author(s):  
Mouhat Ouadia ◽  
Abdellatif Khamlichi ◽  
Ali Limam
Keyword(s):  
Limit State ◽  
Weld Zone ◽  
Stiffened Panel ◽  
Material Strength ◽  
Heat Affect Zone ◽  
Material Degradation ◽  
Geometric Imperfections ◽  
Stiffened Panels ◽  
Friction Stir ◽  
Initial Geometric Imperfections

Buckling of stiffened panels is strongly affected by initial geometric imperfections. The panel assembling technique used can influence both the initial geometric imperfections pattern and material inohomogeneities. It was recognized for the particular case of stir friction welded stiffened panels that the presence of a weld can decrease significantly buckling strength. This is mainly due to the reduction in material strength in the weld zone. In this work, stir friction welded stiffened panels are modeled by using the finite element method. The modelling takes into account distributed and localized initial geometric imperfections as well as material degradation that are generated in the heat affect zone by this process. A parametric study was conducted on the effects of magnitude of geometric distributed imperfections; position, length and depth of a localized depression; as well as material degradation occurring near the weld stripe. Artificial neural network models were built by using the results of various simulations performed according to full factorial design of experiment tables. This has enabled to assess reliability of design of a stiffened panel with regards to the buckling limit state by means of Monte Carlo approach.

Analysis of Residual Stress Effect on Fatigue Crack Propagation in Bonded Aeronautical Stiffened Panels

2011 ◽  
Vol 681 ◽  
pp. 236-242 ◽  
Author(s):  
Ivan Meneghin ◽  
Goran Ivetic ◽  
Enrico Troiani
Keyword(s):  
Residual Stress ◽  
Fatigue Crack ◽  
Crack Propagation ◽  
Fatigue Crack Propagation ◽  
Stress Fields ◽  
Stiffened Panel ◽  
Stress Effect ◽  
Adhesively Bonded ◽  
Stiffened Panels ◽  
Residual Stress Effect

The application of adhesively bonded straps made of high-static strength materials on aeronautical stiffened panels to retard the fatigue skin crack growth is currently a topical research subject. The detrimental effect of the residual stress fields induced as a consequence of the dissimilar coefficients of thermal expansion of the skin and strap materials on the fatigue skin crack propagation was investigated. The residual stresses induced in a stiffened panel representative of a pressurized fuselage shell with titanium doublers in the middle of the stringer bays is numerically quantified for two likely operational temperatures. Their effect on the fatigue crack propagation is analyzed by means of a linear elastic fracture mechanics approach. The results show that adhesively bonded straps on the cracked surface can significantly retard the fatigue crack propagation but, in order to achieve reliable and conservative predictions on their performances, the effect of the residual stress fields they introduce must be taken into account.

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