Intermittent Welding Research Articles

座屈拘束ブレースの脆性破壊に関する実験的研究

The authors conceived a buckling-restrained braces (BRBs) providing stable hysteretic characteristic even under high-strain conditions. In the past paper, conducting cyclically static loading tests, the performance evaluation formula of the buckling-restrained braces was presented. By making core plate form of BRBs into a cruciform, the width direction of that can be made smaller than that of flat steel. In this way, when BRBs with cruciform applies to buildings, it becomes easier to secure openings. However, welding is necessary for assembling of core plate on this occasion. When the welding exists, the performance of the BRBs would be decreased. It is necessary to reveal that the problem of strength matching of fluxes which formed welding. In this paper, the specimens with different welding specifications on the core plate of the energy absorption area are fabricated. As a result, 1) the effective cross section of the intermittent fillet welding on core plate is larger, the performance of the specimens is better, and 2) by using welding wires with the even strength of the base metal, BRBs have the even performance of the base metal.

단속 필렛 용접의 변형 특성에 관한 연구

As is well appreciated, welding is the most important fundamental process in manufacturing marine structures. However, weld-induced deformation is inevitable because of the non-uniform distribution of temperature during welding. The deformation caused by welding is one of the principal obstacles in enhancing the productivity in the manufacturing procedure for marine structures. This should be much more seriously considered in the case of the thin blocks found in a ship with multi-deck structures. This paper is concerned with the deformation control of thin panel blocks by applying intermittent welding to fillet welding. In order to investigate the quantitative effect of the intermittent welding, a thermo elasto-plastic analysis was carried out with various welding pitches and plate thicknesses. Welding tests were also carried out to show the validity of the present thermo-elasto-plastic analysis. Numerical analysis results showed good agreement with those of the welding tests. As far as the present numerical results are concerned, it has been seen that a more than 50% reduction in angular distortion can be achieved by applying the intermittent welding because of the low heat input.

Residual stress characteristics of butt-welded flange by finite element analysis

Finite element simulation is utilized in an aluminum alloy 2014 butt-welded flange under AC Tungsten Inert Gas (AC-TIG) welding condition. The simulated results are in good agreement with the residual stress for the plate test using the actual welding parameters. Furthermore, characteristics of residual stress could be investigated in detail in several aspects, such as the welding structures, the welding sequences, the time intervals, preheating, and repair weld. The intermittent welding may be more convenient and advantageous for the practical applications to reduce the stress, and the local repair welding may cause more stress within the repairing region obviously.

Ultimate strength and ductility characteristics of intermittently welded stiffened plates

A series of detailed numerical analyses of stiffened steel plates subjected to in plane longitudinal or transverse compressive load is performed. Stiffened plates are selected from the deck structure of real sea-going ships and inland waterway vessels. Three different stiffener-to-plate welding procedures are considered: continuous welding, chain intermittent fillet welding and staggered intermittent fillet welding. Special attention is paid to finite element modelling of the fillet welds as applied in practice to verify the reliability of the FEM. Some available experimental results are simulated verifying the reliability of the finite element method. Full-range equilibrium paths are traced for non-linear elasto-plastic response of the stiffened plates, using a commercially available FEM programme, ADINA. Strength and ductility characteristics of the stiffened plates are discussed in details.

박판 패널 용접부의 용접 기법에 따른 좌굴 변형에 관한 연구

The purpose of this study is to propose the proper fillet welding process for preventing the buckling distortion in thin panel welded structure. In order to do it, a heat input model for laser hybrid welding process was developed using FEA and experiment. The principal factors controlling the angular distortion and longitudinal shrinkage force caused by FCA and laser hybrid welding were identified as the welding heat input and weld rigidity using FEA. The predictive equations of angular distortion and longitudinal shrinkage force for each welding process were formulated as a function of the principal factors proposed. With the predictive equations, the buckling distortion at the thin panel welded structure with welding process was evaluated and compared using nonlinear buckling analysis and STEM(simplified thermo elastic method). Based on the results, the best way to prevent the buckling distortion at the given welded panel structures was identified as an intermittent FCA welding.

Ultimate Strength and Ductility Characteristics of Intermittently Welded Stiffened Plates Under In-Plane Axial Compression

The ultimate strength and ductility characteristics of the intermittently welded stiffened plates under the action of in-plane axial compression are investigated in this paper. A series of detailed numerical analyses of longitudinally stiffened steel plates subjected to in-plane compressive load is performed using the ADINA commercial finite element code. Complete equilibrium paths are traced up to collapse for a nonlinear elastic-plastic response of stiffened plates. Analyzed stiffened plates are imperfect and their aspect ratio, plate slenderness, and column slenderness are changed in a systematic manner. Different types of stiffener are chosen for stiffened plate models. Three different stiffener-to-plate welding procedures are considered: continuous, chain intermittent, and staggered intermittent fillet welding.

A comparative study on three different construction methods of stiffened plates-strength behaviour and ductility characteristics

Strength and ductility characteristics of non-continuously welded stiffened plates under in plane axial compression are the main focus of this research. A series of detailed numerical analyses of stiffened steel plates subjected to in plane compressive load is performed. Complete equilibrium paths are traced up to collapse for non-linear elastoplastic response of stiffened plates. Stiffened plates are selected from the deck structure of real sea-going ships and inland waterway vessels. Three different stiffener-to-plate welding procedures are considered: continuous, chain intermittent and staggered intermittent fillet welding. Special attention is paid to the finite element modeling of the fillet welds in either of welding practices. Some available tests are simulated applying finite element method.

Numerical study on the permissible gap of intermittent fillet welds of longitudinally stiffened plates under in plane axial compression

Intermittent fillet welding of stiffeners to plates and its influence on the collapse behaviour of stiffened plates is investigated applying the finite element method. Special attention is paid to the modelling of the fillet welds at the plate-to-stiffener junction. Some available experimental results are simulated in order to obtain reliable numerical results. A series of numerical analyses of stiffened steel plates subjected to an in plane axial compressive load has been performed. Stiffened plates are selected from the deck structure of real sea-going ships and inland waterway vessels. Complete equilibrium paths are traced up to collapse for the non-linear elastoplastic response of stiffened plates. Finally a proposal is presented for the permissible gap of welds in intermittent fillet welding of stiffened plates.

Control of Distortion in Thin Ship Panels

The increased use of thin section (i.e., less than 10-mm (3/8-in.) thick) steel in ship panel construction has aggravated distortion problems, adding to the costs for fitting and flame straightening. This paper describes the results of a study to evaluate techniques for control of distortion in thin panels used in ship construction. The objective of this project is to identify cost effective techniques for controlling distortion. Buckling is usually the dominant mode of distortion in thin panels, followed by angular distortion. Means of reducing both forms of distortion are discussed. During the design phase relatively small adjustments to the design, such as changing plate thickness or stiffener spacing, can significantly reduce distortion. Improving manufacturing techniques, including reducing weld size, implementing intermittent welding, and restraining the panel during welding, can also make a major impact on reducing distortion. New techniques such as egg-crate construction, laser welding, thermal tensioning, back-side line heating, back-bending, and weld quenching also show promise.

Improving the stabilisation of arc ignition in producing short and intermittent welds

(1990). Improving the stabilisation of arc ignition in producing short and intermittent welds. Welding International: Vol. 4, No. 4, pp. 307-309.

Fatigue strength of a groove weld on steel backing

Groove welding made from one side is a common fabrication technique for joints in steel structures. If a steel backing bar is used, current (1988) North American specifications require that it be removed after welding and the weld ground flush if the detail is oriented transversely to the direction of stress and loaded in fatigue. This is an expensive, and in some cases impractical, procedure. British specifications permit the detail to be used but assign a very restrictive fatigue category. In the investigation reported herein, data concerning the fatigue strength of a groove weld with steel backing bar have been obtained experimentally. The backing bar was attached with intermittent fillet welds. A finite element analysis was used to assist in interpretation of the test results. The analysis showed that high local stresses are present at the toe of the fillet weld. However, high stresses also exist at the flush-ground face of the groove weld, and in the physical tests all fatigue cracks started at this side of the detail. When this detail is present in a structure that is subjected to a fatigue loading, Category C of the AASHTO or CSA specifications will provide a suitable basis for design. The selection of categories Class F or G from the British Standard (depending upon the proximity of the fillet welds to the edge of the plate) is too conservative.

Reduced Fillet Weld Sizes for Naval Ships

Recently, Ingalls Shipbuilding Division of Litton updated its fillet weld design practices for naval ship construction. This task was part of a continuing effort to improve accuracy control by decreasing weld-caused distortion. Recent material properties and a more rigorous engineering analysis were used to reduce the required fillet sizes by about 25 percent for steel and about 50 percent for aluminum. The analysis method was developed for the Navy at Newport News Shipbuilding during the 1970's. Intermittent weld tables were developed and, where utilized, proved to be a very cost-effective distortion control measure. Reducing the amount of weld reduces distortion and economically improves accuracy control. Fabrications costs were significantly reduced. This paper reviews the methods and properties used to develop and implement the new weld tables. The benefits to distortion control and construction costs are also discussed.

Interactive computer-aided load and resistance factor design of plate girders

Based on the newly proposed load and resistance factor design specification for steel buildings, an interactive microcomputer program is presented for design of welded stiffened steel plate girders. The program is capable of designing hybrid girders and takes into account the tension-field action of the web. The loading on the girder may consist of a uniformly distributed load plus any number of concentrated loads. Single or double plates may be used as transverse stiffeners. For flangeto-web connections, either continuous or intermittent fillet weld may be specified. The program rounds off the thickness and width of the flange plates and stiffeners and the thickness of the web plate to practical sizes according to the increments specified by the user/designer. This program demonstrates the effectiveness of microcomputers in practical design of structures.

Fatigue strength of a groove weld on steel backing

Groove welding made from one side is a common fabrication technique for joints in steel structures. If a steel backing bar is used, current (1983) North American specifications require that it be removed after welding and the weld ground flush if the detail is to be located transversely to the direction of stress and fatigue loaded. This is an expensive, and in some cases impractical, procedure. In the investigation reported herein, data concerning the fatigue strength of a groove weld with steel backing bar detail have been obtained experimentally. The backing bar was attached with intermittent fillet welds. A finite element analysis has been used to assist in interpretation of the test results.The analysis showed that high local stresses are present at the toe of the fillet weld. However, high stresses also exist at the flush-ground face of the groove weld, and the test results indicated that all fatigue cracks started at this side of the detail. When this detail is present in a structure and subjected to a fatigue loading, category C of the AASHTO or CSA specifications will provide a suitable basis for design. Key words: failure, fatigue, steel, welding.

高炭素鋼のガスシールドアーク溶接に関する研究 ＩＩＩ 溶接部の機械的性質に及ぼすＳの影響

Mainly mechanical properties of high carbon steel (0.65-0.70%C, 0.008-0.026%S) welds for narrow gap (gap; 10 mm) butt welding in the flat position (build up process; intermittent, continuous) and vertical position (continuous) have been investigated by CO2+20%O2 gas shielded arc welding.The results obtained are as follows:(1) In case of tensile tests of welded joints by butt welding in the flat position (intermittent), excellent tensile properties with break down in weld metal and base metal are obtained for 0.008%S base metal. Tensile properties decrease as sulphur contents increase from 0.014%S to 0.026%S and Fractured position are almost in heat affected zone. For different base metals, tensile properties of welded joints by continuous welding are lower than by intermittent welding and fractured position by continuous welding are almost in heat affected zone. In case of vertical welding, excellent tensile properties with break down in base metal are obtained for different base metals.(2) In case of rotating bending fatigue tests of welded joints by butt welding in the flat position and vertical welding, excellent fatigue strength are obtained for 0.008%S, 0.020%S base metals. In case of welded joints in the flat position for 0.026% S base metal, low fatigue strength are obtained and fractured origin exists at intercrystalline crack in heat affected zone for continuous welding.

INFLUENCE ON STRENGTH OF COMPRESSION PANEL OF STIFFENER SECTION, SPACING AND WELDED CONNECTION.

Keywords MANCHESTER UNIVERSITY, CARDIFF UNIVERSITY COLLEGE INFLUENCE, PANELS, SPACING, TESTS, WIDTH, LIMITS, STRESS, WELDING, RULES, COLLAPSE, ESTIMATES, RIGS, STRENGTH, STIFFENERS, WELDED, STIFFENED, THICKNESS, BUCKLING, EFFECT, INTERMITTENT, WORKMANSHIP, TORSIONAL, CARRYING, INSTRUMENTATION, COMPRESSION, SECTIONS, CONNECTIONS, PLATES, RATIOS, RESIDUAL, CONTINUOUS, INTERIM, FAILURES, CAPACITY... Show All

高マンガン鋼クロッシングと炭素鋼レールとの自動溶接 溶接法の改善と溶接部の諸性質

A study was made about automatic welding method in order to join carbon steel rail to high Mn steel crossing.When a continuous welding under electro-gas welding method was made, there appeared transverse cracks at heat affected zone of high Mn steel.The main cause of these cracks was supposed to be micro-shrinkage and severer britteleness than expected. Further, there appeared slag inclusion in electro-gas weld. And so, an intermittent welding was tried next. Togther with everlasting water cooling welded part of high Mn steel is cooled per each 1 layer 3 pass welding cutting arc. Therefore, a curved type torch epuipped with automatic swinging device was manufactured.The toughness of heat affected zone of high Mn steel by 1 layer 3 pass procedure is equal to that of shielded metal arc weld which has already been employed as practical application.Concerning the special features the results of fatigue test are the same as those of the enclosed welding of carbon steel rail.About shock test, there proved to be sufficiently ductile at the weld.

アルミニウムおよびその合金の溶接割れに関する研究

A modified FISCO type cracking test was used to study the cracking properties of inert-gas metalarc welds in commercially pure aluminium (2S) and aluminium-magnesium alloys (52S, 54S and 56S).An automatic welding head was employed to make intermittent welds in FISCO type specimens and the cracks were detected by X-ray radiographic and fluorescent penetrant methods.Weld metal cracks were studied by classifying into four types, namely, longitudinal crack at the start of a bead, longitudinal crack in the intermediate portion of a bead, crater crack and longitudinal crack throughout the bead.The results obtained in the experiment were as follows.1. It is possible to compare weld cracking tendencies of Al and Al-Mg alloys by the modified FISCO type cracking test. Weld cracking tendency was not so serious for a plate thickness of 12 mm, but greatly increased for greater thickness of 20 and 30 mm.2. Longitudinal cracks at start or in intermediate portion were increased with increase of welding speed, root opening or plate thickness.3. Crater cracks were made greater with increase of welding current and decreased with welding speed, since the size of crater changed itself with them.5. Variation in arc voltage scarcely affected the weld metal cracking.5. Vee-grooved specimens were more crack-sensitive than I-grooved ones.6. Among several combinations of welding wires and plates, the most crack-sensitive one was 2S wire-51S plate or 52S wire-2S plate. The combination of 52S wire and 52S plate came next. The three combinations, 2S wire-2S plate, 54S wire-52S plate and 56S wire-52S plate, were equally less crack-sensitive than the above three ones.In other words, the weld metals with their magnesium contents between 1 and 2 percentages showed e greatest crack sensitivity, while both the lower and higher magnesium content regions gave far better cracking resistance.7. For the prevention of weld cracking, welding should be done with lower welding speed and a suitable value of welding current, an adequate choise of welding wire and a suitable welding procedure at the start of bead are also necessary. At the end of a weld the bead should run off the groove onto the plate surface and the crater should be finished with a crater filler method.

鋳鉄熔接の亀裂防止(I)

A simple method-to avoide the welding crack of cast iron is described here.Before welding, shallow glooves were made on the surface of mother metal adjascent to the V-groove as shown in Fig. 6. Cast iron was repaired by nickel electrode or mild steel electrode with standard welding procedure of cast iron which contains low welding current, intermittent welding and peening of the deposit etc. The occurence of welding crack was diminished remarkably by the effect of these shollow grooves.As the reasons, geometrical surface ductility and ductility accompanied by the instantenous high temperature caused by the gloove at the surface adjascent to the weld may be taken into account. Table 1 shows the maximum temperature which can be measured and the apparent elongation measured at the gloove.

Bending Rigidity of a Welded Girder Effect of Various Type and Size of Fillet Welds-

The object of this paper was to provide a basis for substantiating current specifications governing the use of intermittent fillet welds to connect the component parts of structural members. For instance, the bending rigidity is varied from a laminated girder to a solid one according to the type and size of fillet welds. So we studied in this paper the effects of leg length, pitch and flange thickness on the bending rigidity of a composed I-beam with various type and size of continuous or intermittent fillet welds. The concentrated lateral load was applied to a welded I-beam with both ends supported, and the deflections measured at nine points by dial gauges were compared with that of a solid one with the same cross section. The bending rigidity coefficient η of a welded girder can be estimated by equivalent leg length from this experimental results as follows.η=1/(K1-K2/1)+K2tanhφl/2/φl+K3/φ2l2(1-2tanhφl/2/φl)and φl=α(2Le/t1)β{γ+δ(2h1/t2)}whereK1={1+6h22EI0/l2(2I1+I2)G}/1+12kEI0/l2A0GK2=24EA1(h1+h2)/l2G{h22(h1+h2)/2I1+I2-1/t2}/1+12kEI0/l2A0GK3=24A1(h1+h2)2/2I1+I2/1+12kEI0/l2A0GIn respect of ultimate load, as it was varied from the various conditions such as leg length, pitch, joint types and dimensions of specimens, the ultimate load of the staggard was higher than the chain if the leg length was same. Types of fracture, classified in three types namely shear fracture of fillets, lateral buckling and local buckling, should be considered in case of the estimation of ultimate load of specimen.