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Article
Publication date: 7 December 2015

Nikolai Kashaev, Stefan Riekehr, Kay Erdmann, Alexandre Amorim Carvalho, Maxim Nurgaliev, Nikolaos Alexopoulos and Alexandra Karanika

Composite materials and metallic structures already compete for the next generation of single-aisle aircraft. Despite the good mechanical properties of composite materials…

Abstract

Purpose

Composite materials and metallic structures already compete for the next generation of single-aisle aircraft. Despite the good mechanical properties of composite materials metallic structures offer challenging properties and high cost effectiveness via the automation in manufacturing, especially when metallic structures will be welded. In this domain, metallic aircraft structures will require weight savings of approximately 20 per cent to increase the efficiency and reduce the CO2 emission by the same amount. Laser beam welding of high-strength Al-Li alloy AA2198 represents a promising method of providing a breakthrough response to the challenges of lightweight design in aircraft applications. The key factor for the application of laser-welded AA2198 structures is the availability of reliable data for the assessment of their damage tolerance behaviour. The paper aims to discuss these issues.

Design/methodology/approach

In the presented research, the mechanical properties concerning the quasi-static tensile and fracture toughness (R-curve) of laser beam-welded AA2198 butt joints are investigated. In the next step, a systematic analysis to clarify the deformation and fracture behaviour of the laser beam-welded AA2198 four-stringer panels is conducted.

Findings

AA2198 offers better resistance against fracture than the well-known AA2024 alloy. It is possible to weld AA2198 with good results, and the welds also exhibit a higher fracture resistance than AA2024 base material (BM). Welded AA2198 four-stringer panels exhibit a residual strength behaviour superior to that of the flat BM panel.

Originality/value

The present study is undertaken on the third-generation airframe-quality Al-Li alloy AA2198 with the main emphasis to investigate the mechanical fracture behaviour of AA2198 BMs, laser beam-welded joints and laser beam-welded integral structures. Studies investigating the damage tolerance of welded integral structures of Al-Li alloys are scarce.

Details

International Journal of Structural Integrity, vol. 6 no. 6
Type: Research Article
ISSN: 1757-9864

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Article
Publication date: 7 October 2020

Liang Tian and Yu Luo

The purpose of this paper is to quantitatively investigate the effect of process parameters (including welding current, voltage and speed) and plate thickness on in-plane…

Abstract

Purpose

The purpose of this paper is to quantitatively investigate the effect of process parameters (including welding current, voltage and speed) and plate thickness on in-plane inherent deformations in typical fillet welded joint; meanwhile, the plastic strains remaining in the weld zone are also analyzed under different influencing factors.

Design/methodology/approach

To achieve the purpose of this study, a thermal-elastic-plastic finite element (TEP FE) model is developed to analyze the thermal-mechanical behavior of the T-welded joint during the welding process. Experimental measurements have verified the validity of the established TEP FE model. Using the effective model, a series of numerical experiments are performed to obtain the inherent deformations under the conditions of different influencing factors, and then the calculation results are discussed based on the relevant data obtained.

Findings

Through numerical simulation analysis, it is found that the longitudinal and transverse inherent deformations decrease with the increase of welding speed and plate thickness, whereas as the nominal heat input increases, the inherent deformations increase significantly. The longitudinal shrinkage presents a quasi-linear and nonlinear distribution in the middle and end of the weld, respectively. The plastic strains in the cross section of the T-joint also vary greatly because of the process parameters and plate thickness, but the maximum value always appears near the location of the welding toe, which means that this point faces a relatively large risk of fatigue cracking. The inherent deformations are closely related to the plastic strains remaining in the weld zone and are also affected by many influencing factors such as process parameters and plate thickness.

Research limitations/implications

In this study, relatively few influencing factors such as welding current, voltage, speed and plate thickness are considered to analyze the inherent deformations in the T-welded joint. Also, these influencing factors are all within a certain range of parameters, which shows that only limited applicability can be provided. In addition, only in-plane inherent deformations are considered in this study, without considering the other two out-of-plane components of inherent deformations.

Originality/value

This study can help to expand the understanding of the relationship between the inherent deformations and its influencing factors for a specific form of the welded joint, and can also provide basic data to supplement the inherent deformation database, thereby facilitating further researches on welding deformations for stiffened-panel structures in shipbuilding or steel bridges.

Details

Engineering Computations, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 0264-4401

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Article
Publication date: 31 January 2020

Taiwo Ebenezer Abioye, Igbekele Samson Omotehinse, Isiaka Oluwole Oladele, Temitope Olumide Olugbade and Tunde Isaac Ogedengbe

The purpose of this study is to determine the effects of post-annealing and post-tempering processes on the microstructure, mechanical properties and corrosion resistance…

Abstract

Purpose

The purpose of this study is to determine the effects of post-annealing and post-tempering processes on the microstructure, mechanical properties and corrosion resistance of the AISI 304 stainless steel gas metal arc weldment.

Design/methodology/approach

Gas metal arc welding of AISI 304 stainless steel was carried out at an optimized processing condition. Thereafter, post-annealing and post-tempering processes were performed on the weldment. The microstructure, mechanical and electrochemical corrosion properties of the post-weld heat treated samples, as compared with the as-welded, were investigated.

Findings

The as-welded joint was characterized with sub-granular grain structure, martensite formation and Cr-rich carbides precipitates. This made it harder than the post-annealed and post-tempered joints. Because of slower cooling in the furnace, the post-annealed joint contained Cr-rich carbides precipitates. However, the microstructure of the post-tempered joint is more refined and significantly devoid of the carbide precipitates. Post-tempering process improved the elongation (∼23%), tensile (∼10%) and impact (∼31%) strengths of the gas metal arc AISI 304 stainless steel weldment, while post-annealing process improved the elongation (∼20%) and impact strength (∼72%). Owing to the refined grain structure and significant elimination of the Cr-rich carbide precipitates at the joint, the post-tempered joint exhibited better corrosion resistance in 3.5 Wt.% NaCl solution than the post-annealed and the as-welded joints.

Originality/value

The appropriate post-weld heat treatment that enhances microstructural homogeneity and quality of the AISI 304 gas metal arc welded joint was determined.

Details

World Journal of Engineering, vol. 17 no. 1
Type: Research Article
ISSN: 1708-5284

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Article
Publication date: 19 May 2020

Chunliang Niu, Suming Xie, Xiangwei Li and Wen Wang

In order to use the BS EN 15058-3 principle more scientifically to design the welding structure of rail vehicles, a method of stress state assessment of welding joints…

Abstract

Purpose

In order to use the BS EN 15058-3 principle more scientifically to design the welding structure of rail vehicles, a method of stress state assessment of welding joints meeting the requirements of BS EN 15058-3 is proposed by using IIW-2008 and ASME-BPVC-VIII-2:2015 standard.

Design/methodology/approach

The stress state evaluation process of two standards is studied, and the stress state evaluation method of two standards is programmed by computer language. Among them, ASME standard can evaluate the stress state of welding structures without defects and with defects. In order to verify the feasibility of the method, under the fatigue load of en13749 standard, the method is applied to the welding structure design of the rail car frame.

Findings

The results show that the evaluation based on IIW-2008 standard is stricter, and the stress factor of the weld between the crossbeam and the traction pull rod seat is the largest, the value is 0.881, and the stress state grade is medium. With the increase of the number of defects, the stress level of the welded joint increases and the fatigue life decreases.

Originality/value

This study can provide a reference for the welding design of rail vehicles and other complex structures and has a certain engineering guiding significance.

Details

International Journal of Structural Integrity, vol. 12 no. 1
Type: Research Article
ISSN: 1757-9864

Keywords

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Article
Publication date: 30 August 2011

Yoshihiro Sakino, Yuji Sano and You‐Chul Kim

Laser peening without coating (LPwC) is an innovative surface enhancement technology for introducing compressive residual stress in metallic materials. The purpose of this…

Abstract

Purpose

Laser peening without coating (LPwC) is an innovative surface enhancement technology for introducing compressive residual stress in metallic materials. The purpose of this study is to examine the characteristic at the laser‐peened welded zone and the fatigue lives of the welding joints.

Design/methodology/approach

LPwC conditions for 490 MPa grades of structural steels were selected. By using the conditions, the characteristic at the laser‐peened welded zone, residual stresses, hardness and roughness of welding toes were examined. Moreover, the fatigue lives of the toes of box‐welded joints and butt welded joints pre‐treated by LPwC were compared to the fatigue lives of those that were not pre‐treated by LPwC.

Findings

The main results are: LPwC conditions for 490 MPa grade steels were established; residual stresses, Vickers hardness and roughness at the laser‐peened welded zone were revealed; and LPwC can dramatically extend the fatigue life of welded joint.

Originality/value

The effects of LPwC on structural steels, which are widely used in bridge members, have not been well clarified; the effect of LPwC on welded zones in these structures is particularly unclear. If LPwC can be carried out such that compressive residual stress is imparted on structural steels and the welded zones in the bridge members, the fatigue lives of bridge members will be greatly increased. The paper fills some of these gaps.

Details

International Journal of Structural Integrity, vol. 2 no. 3
Type: Research Article
ISSN: 1757-9864

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Article
Publication date: 2 February 2015

A. Krasovskyy and A. Virta

Even though modern welding technology has improved, initial defects on weld notches cannot be avoided. Assuming the existence of crack-like flaws after the welding

Abstract

Purpose

Even though modern welding technology has improved, initial defects on weld notches cannot be avoided. Assuming the existence of crack-like flaws after the welding process, the stage of a fatigue crack nucleation becomes insignificant and the threshold for the initial crack propagation can be used as a criterion for very high cycle fatigue whereas crack growth analysis can be applied for the lifetime estimation at lower number of cycles. The purpose of this paper is to present a mechanism based approach for lifetime estimation of welded joints, subjected to a multiaxial non-proportional loading.

Design/methodology/approach

The proposed method, which is based on the welding process simulation, thermophysical material modeling and fracture mechanics, considers the most important aspects for fatigue of welds. Applying worst-case assumptions, fatigue limits derived by the weight function method can be then used for the fatigue assessment of complex welded structures.

Findings

An accurate mechanism based method for the fatigue life assessment of welded joints has been presented and validated.

Originality/value

Compared to the fatigue limits provided by design codes, the proposed method offers more accurate lifetime estimation, a better understanding of interactions between welding process and fatigue behavior. It gives more possibilities to optimize the welding process specifically for the considered material, weld type and loading in order to achieve the full cost and weight optimization potential for industrial applications.

Details

International Journal of Structural Integrity, vol. 6 no. 1
Type: Research Article
ISSN: 1757-9864

Keywords

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Article
Publication date: 8 August 2020

Suming Xie, Chunyun Li, Jian Wang, Wanpeng Li and Chunliang Niu

Based on the DVS1608-2011 and IIW-2008 and BS EN15085-3 standards, the stress state grade of welded joints of aluminum alloy EMU (Electric Multiple Units) body was studied.

Abstract

Purpose

Based on the DVS1608-2011 and IIW-2008 and BS EN15085-3 standards, the stress state grade of welded joints of aluminum alloy EMU (Electric Multiple Units) body was studied.

Design/methodology/approach

First, the calculation methods of the stress state grade of aluminum alloy welded joints analyzed by DVS1608-2011 and IIW-2008 standards were studied, and the two methods were programmed by the APDL language of ANSYS. Then, the finite element model of aluminum alloy EMU body was established; the static strength calculation result of the body was compared with the test result, and the error is basically within 10%. Finally, under the acceleration fatigue load provided by BS EN12663 standard, the fatigue analysis was carried out on the welded joint of the vehicle body, and the stress state of the welded joint of the vehicle body was studied according to IIW-2008 and DVS1608 standards, respectively.

Findings

The results show that the assessment method based on IIW-2008 standard is more rigorous, and the maximum stress factor of the longitudinal weld between the side beam and the side wall is 0.811; the position occurs in the area where the longitudinal weld of the side beam and the side wall is close to the lower door angle.

Originality/value

The stress state is medium, and the rest of the weld stress states are low.

Details

International Journal of Structural Integrity, vol. 12 no. 1
Type: Research Article
ISSN: 1757-9864

Keywords

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Article
Publication date: 1 January 1940

Kurt Queitsch

The formation of internal stresses is mainly caused by contraction of the material. As the magnitude of shrinkage is dependent upon many factors, it cannot be predicted…

Abstract

The formation of internal stresses is mainly caused by contraction of the material. As the magnitude of shrinkage is dependent upon many factors, it cannot be predicted with accuracy. Not only the technique and the rate of welding are of importance but also the material and the design. Finished welded components often show quite considerable reductions in their major dimensions. With larger welded structures, such as engine mountings and steel tube fuselages, which ought to have certain dimensions absolutely accurate for assembly requirements, the contraction and the distortion duo to welding should be considered in every case.

Details

Aircraft Engineering and Aerospace Technology, vol. 12 no. 1
Type: Research Article
ISSN: 0002-2667

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Article
Publication date: 2 February 2021

Waseem Arif, Hakim Naceur, Sajjad Miran, Nicolas Leconte and Eric Markiewicz

The purpose of this study is to develop an elasto-plastic multi-material shell model by which finite element analysis of laser welded joints is carried out at the…

Abstract

Purpose

The purpose of this study is to develop an elasto-plastic multi-material shell model by which finite element analysis of laser welded joints is carried out at the interface of the heat-affected zone and base material.

Design/methodology/approach

The multi-material shell model is implemented on the simple cantilever and double cantilever welded plates to examine the efficiency of the developed model.

Findings

By reducing the computational time approximately 20 times with the developed model, the results obtained in the form of von Mises stress and equivalent plastic strain are found in good agreement as compared with the reference solid model.

Originality/value

The accurate and fast prediction of the stresses and strains in the laser welded joints, and the developed multi-material model is helpful to simulate complex industrial welded structures.

Details

Engineering Computations, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 0264-4401

Keywords

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Article
Publication date: 1 February 1941

Ing. E. Reichel

THE first electrical welding tests by the Arado firm were carried out at Warnemiinde in the year 1933 with a Rudolf welding machine. These tests were suggested by the…

Abstract

THE first electrical welding tests by the Arado firm were carried out at Warnemiinde in the year 1933 with a Rudolf welding machine. These tests were suggested by the welding of seaplane float frames by the Heinkcl firm, under the direction of Koppenhöfer, with machines of the same type. The results obtained with this welding machine were not very satisfactory since it was not possible, owing to the mechanical operation of the switch, to obtain uniform spot‐welds. The machine had the further disadvantage that the commutator contacts became badly overheated and had to be frequently cleaned. In order to improve the spot‐welding by this machine an agreement was reached with the I. G. Farbenindustrie in Bitterfeld in the autumn of 1933; as a result of which further tests were made with this same machine by the I. G. concern itself at Bitterfeld.

Details

Aircraft Engineering and Aerospace Technology, vol. 13 no. 2
Type: Research Article
ISSN: 0002-2667

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