• Title/Summary/Keyword: Welded structures

Search Result 545, Processing Time 0.032 seconds

The Application of welding numerical simulation on two typical welded structures in railway vehicles

  • Ya-na, Li;Cheng-tao, Li;Bin, Yuan;Su-ming, Xie
    • Interaction and multiscale mechanics
    • /
    • v.5 no.2
    • /
    • pp.145-155
    • /
    • 2012
  • The thin-plate structure and the box-beam structure are two typical welded structures in railway vehicles. Because of their structure complexity, bigger size and multi-seams, welding residual distortion which occur in welding process bring unfavorable effect on the quality of welding products manufacturing and service. As a result, welding distortion forecasting and control become an important and urgent research topic in railway vehicles. In this paper, three different numerical methods are presented corresponding to three typical types of welded structures of railway vehicles and welding deformation are simulated. Consistence of numerical results and experimental data proves the correctness of models and feasibility of simulation methods.

Push-out resistance of concrete-filled spiral-welded mild-steel and stainless-steel tubes

  • Loke, Chi K.;Gunawardena, Yasoja K.R.;Aslani, Farhad;Uy, Brian
    • Steel and Composite Structures
    • /
    • v.33 no.6
    • /
    • pp.823-836
    • /
    • 2019
  • Spiral welded tubes (SWTs) are fabricated by helically bending a steel plate and welding the resulting abutting edges. The cost-effectiveness of concrete-filled steel tube (CFST) columns can be enhanced by utilising such SWTs rather than the more conventional longitudinal seam welded tubes. Even though the steel-concrete interface bond strength of such concrete-filled spiral-welded steel tubes (CF-SWSTs) is an important consideration in relation to ensuring composite behaviour of such elements, especially at connections, it has not been investigated in detail to date. CF-SWSTs warrant separate consideration of their bond behaviour to CFSTs of other tube types due to the distinct weld seam geometry and fabrication induced surface imperfection patterns of SWTs. To address this research gap, axial push-out tests on forty CF-SWSTs were carried out where the effects of tube material, outside diameter (D), outside diameter to wall thickness (D/t), length of the steel-concrete interface (L) and concrete strength grade (f'c) were investigated. D, D/t and L/D values in the range 102-305 mm, 51-152.5 and 1.8-5.9 were considered while two nominal concrete grades, 20 MPa and 50 MPa, were used for the tests. The test results showed that the push-out bond strengths of CF-SWSTs of both mild-steel and stainless-steel were either similar to or greater than those of comparable CFSTs of other tube types. The bond strengths obtained experimentally for the tested CF-SWSTs, irrespective of the tube material type, were found to be well predicted by the guidelines contained in AISC-360.

Fatigue Life Analysis of Butt-welded Joint with and without Postweld Heat Treatment by Local Strain Approach (국부변형률 방법을 이용한 용접후열처리 전후 시편의 피로수명 해석)

  • Lee, Dong-Hyoung;Seo, Jeong-Won;Goo, Byeong-Choon;Seok, Chang-Sung
    • Proceedings of the KSME Conference
    • /
    • 2003.11a
    • /
    • pp.1086-1091
    • /
    • 2003
  • The problem of residual stresses and fatigue behavior in welded structures is the main concern of welding research fields. The residual stresses and distortions of structures by welding exert negative effect on the safety of mechanical structures. Postweld heat treatment is usually carried out to relieve this residual stresses of welded joints. In this paper the influence of postweld heat treatment on fatigue life of butt-welded joint was investigated. To predict the effect of PWHT, an analytical model is developed by finite element and local strain approach and the result of fatigue life analysis is compared to experimental results. It is demonstrated that fatigue life estimates closely approximate the experimental results and PWHT provides some increase of fatigue lives in long-life fatigue region and no increase in short-life fatigue region because of the residual stress relaxation under tensile loads.

  • PDF

Experiments and Finite Element Analysis for the Estimation of Stress Relief in Welded Structures (반복 하중을 받는 용접 구조물의 잔류 응력 저감 파악을 위한 유한요소 해석 및 실험적 연구)

  • Yang, Yong-Sic;Kang, Joong-Kyoo;Lee, Jang-Hyun;Kim, Sung-Chan;Hwang, Se-Yum
    • Journal of the Society of Naval Architects of Korea
    • /
    • v.48 no.3
    • /
    • pp.238-245
    • /
    • 2011
  • Welding inevitably introduces the residual stresses which affect the fatigue strength of the joint structure. The mitigation of fatigue strength depends on the residual stress magnitude and distribution. Stress relief analyses are of practical interest for all cyclic loaded welded structures, such as ships and offshore structures. In order to estimate the effects of relaxation of residual stresses in the welded structure, this paper presents a finite element analysis procedure and experimental results for the welded structure. Cruciform specimens joint by MAG welding have been tested to measure the released stress. Relieved welding residual stresses obtained by finite element analysis are compared with those measured by experiment.

Welded plate and T-stub tests and implications on structural behavior of moment frame connections

  • Dong, P.;Kilinski, T.
    • Steel and Composite Structures
    • /
    • v.2 no.1
    • /
    • pp.35-50
    • /
    • 2002
  • A series of tests on simple-welded plate specimens (SWPS) and T-stub tension specimens simulating some of the joint details in moment frame connections were conducted in this investigation. The effects of weld strength mismatch and weld metal toughness on structural behavior of these specimens were considered under both static and dynamic loading conditions. Finite element analyses were performed by taking into account typical weld residual stress distributions and weld metal strength mismatch conditions to facilitate the interpretation of the test results. The major findings are as follows: (a) Sufficient specimen size requirements are essential in simulating both load transfer and constraint conditions that are relevant to moment frame connections, (b) Weld residual stresses can significantly elevate stress triaxiality in addition to structural constraint effects, both of which can significantly reduce the plastic deformation capacity in moment frame connections, (c) Based on the test results, dynamic loading within a loading rate of 0.02 in/in/sec, as used in this study, premature brittle fractures were not seen, although a significant elevation of the yield strength can be clearly observed. However, brittle fracture features can be clearly identified in T-stub specimens in which severe constraint effects (stress triaxiality) are considered as the primary cause, (d) Based on both the test and FEA results, T-stub specimens provide a reasonable representation of the joint conditions in moment frame connections in simulating both complex load transfer mode and constraint conditions.

Role of Post Weld Treatment Methods in the Improvement of Fatigue Life for T-type Welded Structures Made by SM 50A Steel (SM 50A 강으로 제작된 T-형 용접형상의 용접후처리 방법이 피로수명 증가에 작용하는 역할)

  • Han, Chang-Wan;Lee, Jae-Hoon;Song, Jun-Hyouk;Lee, Hyun-Woo;Park, Seong-Hun
    • Journal of the Korean Society for Precision Engineering
    • /
    • v.29 no.3
    • /
    • pp.307-312
    • /
    • 2012
  • This study aims to investigate the effect of the post weld treatments on the fatigue life of T-type welded structure made by a SM50A steel material, generally used for excavators, because changes in the geometry, material and surface properties of welded regions affect the fatigue life of welded structures. T-type test specimens were prepared by the CO2 welding of rolled steel plates (SM50A steel) with a thickness of 10 mm at a welding speed of 30 cm/min and these Ttype welded specimens were further treated by UIT (Ultrasonic Impact Treatment) and/or toegrinding post welding treatment methods. In order to investigate improvements on the fatigue life of the samples. 3-point bending fatigue tests were conducted with a stress ratio of R=0.1 under a cyclic loading environment at a frequency of 5 Hz, via a hydraulic fatigue testing machine (${\pm}100\;kN$, MTS 809). The tests were performed at room temperature. The fatigue life of UIT specimens was approximately 25 times longer than that of as-welded specimens at a stress amplitude of 281 MPa, while toe-grinding specimens exhibited 4.15 times longer fatigue life. The current results could provide important guidelines to determine the proper post weld treatment methodologies of T-type welded parts for excavators with a satisfactory fatigue life although under severe operating conditions.

The comparision of fatigue behavior of $CO_2$ plug weld and resistance spot weld (저항점용접과 $CO_2$ 플러그용접의 피로거동 연구)

  • Jeong, Won-Uk;Jeong, Yeon-Su;Kang, Seong-Su
    • Transactions of the Korean Society of Mechanical Engineers A
    • /
    • v.22 no.3
    • /
    • pp.554-561
    • /
    • 1998
  • Vehicle body structures are formed by thousands of spot welds and fatigue failure of vehicle structures occur near the spot welds after driving a long way at a durability test road. It is necessary to know accurately the reason of the fatigue failure of the spot weld in the developing stage in order to reinforce it. Many investigations have been done regarding the strength of spot welded joints, contributing to understand its fatigue strength. In developing process, a fatigue failed spot welded area can be repaired by $CO_2$ welding or another method to continue the test. To know the effect of reinforcing these welds, several methods of welding were analyzed and compared to spot welding. With the results of this test, the appropriate repair method can be used instead of spot welding during the development of new car and best design guide can be given for the strength. In this study, fatigue and static tensile tests are made and microstructure is investigated for the purpose of estimating the strength of welded joints by using spot welded and $CO_2$ plug welded specimens. The tested specimens are of two types : Tensile-shear type(TS) and L-tension type(LT).

Ductile cracking simulation procedure for welded joints under monotonic tension

  • Jia, Liang-Jiu;Ikai, Toyoki;Kang, Lan;Ge, Hanbin;Kato, Tomoya
    • Structural Engineering and Mechanics
    • /
    • v.60 no.1
    • /
    • pp.51-69
    • /
    • 2016
  • A large number of welded steel moment-resisting framed (SMRF) structures failed due to brittle fracture induced by ductile fracture at beam-to-column connections during 1994 Northridge earthquake and 1995 Kobe (Hyogoken-Nanbu) earthquake. Extensive research efforts have been devoted to clarifying the mechanism of the observed failures and corresponding countermeasures to ensure more ductile design of welded SMRF structures, while limited research on the failure analysis of the ductile cracking was conducted due to lack of computational capacity and proper theoretical models. As the first step to solve this complicated problem, this paper aims to establish a straightforward procedure to simulate ductile cracking of welded joints under monotonic tension. There are two difficulties in achieving the aim of this study, including measurement of true stress-true strain data and ductile fracture parameters of different subzones in a welded joint, such as weld deposit, heat affected zone and the boundary between the two. Butt joints are employed in this study for their simple configuration. Both experimental and numerical studies on two types of butt joints are conducted. The validity of the proposed procedure is proved by comparison between the experimental and numerical results.

Mechanical properties of friction stir welded aluminum alloys 5083 and 5383

  • Paik, Jeom-Kee
    • International Journal of Naval Architecture and Ocean Engineering
    • /
    • v.1 no.1
    • /
    • pp.39-49
    • /
    • 2009
  • The use of high-strength aluminum alloys is increasing in shipbuilding industry, particularly for the design and construction of war ships, littoral surface craft and combat ships, and fast passenger ships. While various welding methods are used today to fabricate aluminum ship structures, namely gas metallic arc welding (GMAW), laser welding and friction stir welding (FSW), FSW technology has been recognized to have many advantages for the construction of aluminum structures, as it is a low-cost welding process. In the present study, mechanical properties of friction stir welded aluminum alloys are examined experimentally. Tensile testing is undertaken on dog-bone type test specimen for aluminum alloys 5083 and 5383. The test specimen includes friction stir welded material between identical alloys and also dissimilar alloys, as well as unwelded (base) alloys. Mechanical properties of fusion welded aluminum alloys are also tested and compared with those of friction stir welded alloys. The insights developed from the present study are documented together with details of the test database. Part of the present study was obtained from the Ship Structure Committee project SR-1454 (Paik, 2009), jointly funded by its member agencies.

On compressive behavior of large welded hollow spherical joints with both internal and external stiffeners

  • Tingting Shu;Xian Xu;Yaozhi Luo
    • Steel and Composite Structures
    • /
    • v.46 no.2
    • /
    • pp.211-220
    • /
    • 2023
  • Welded hollow spherical joints are commonly used joints in space grid structures. An internal stiffener is generally adopted to strengthen the joints when large hollow spheres are used. To further strengthen it, external stiffeners can be used at the same time. In this study, axial compression tests are conducted on four full-scale 550 mm spherical joints. The failure modes and strengths of the tested joints are investigated. It shows that the external stiffeners are able to increase the strength of the joint up to 25%. A numerical model for large spherical joints with stiffeners is established and verified against the experimental results. Parametric studies are executed considering six main design factors using the verified model. It is found that the strength of the spherical joint increases as the thickness, height and number of the external stiffeners increase, and the hollow sphere's diameter has a neglectable effect on the enhancement caused by the external stiffeners. Based on the experimental and numerical results, a practical formula for the compressive bearing capacity of large welded hollow spherical joints with both internal and external stiffeners is proposed. The proposed formula gives a conservative prediction on the compressive capacity of large welded hollow spherical joints with both internal and external stiffeners.