双通线加热的热力学及实验分析(英文)

The present investigation deals with process analysis of oxy-acetylene flame assisted double pass line heating for varying plate thickness. oxy-acetylene flame as the heat source for multi pass line heating to achieve 3-D bending of plates with varying thicknesses was studied. The oxy-acetylene flame was modeled as the moving heat source in the FEM analysis. The transient thermal histories were predicted taking into account the temperature dependent thermo-mechanical properties. A comparative study between single pass and double pass line heating residual deformation was also carried out. The temperature distribution and residual deformations predicted by the numerical model developed in the present work compared fairly well with those of the experimental ones.     

12毫米厚铝合金板的搅拌摩擦焊研究(英文)

Most of the investigations regarding friction stir welding(FSW)of aluminum alloy plates have been limited to about 5 to 6mm thick plates.In prior work conducted the various aspects concerning the process parameters and the FSW tool geometry were studied utilizing friction stir welding of 12 mm thick commercial grade aluminum alloy.Two different simple-tomanufacture tool geometries were used.The effect of varying welding parameters and dwell time of FSW tool on mechanical properties and weld quality was examined.It was observed that in order to achieve a defect free welding on such thick aluminum alloy plates,tool having trapezoidal pin geometry was suitable.Adequate tensile strength and ductility can be achieved utilizing a combination of high tool rotational speed of about 2000 r/min and low speed of welding around 28 mm/min.At very low and high dwell time the ductility of welded joints are reduced significantly.     

水火弯板残余变形预报的数值和量纲分析(英文)

Line heating process is a very complex phenomenon as a variety of factors affects the amount of residual deformations. Numerical thermal and mechanical analysis of line heating for prediction of residual deformation is time consuming. In the present work dimensional analysis has been presented to obtain a new relationship between input parameters and resulting residual deformations during line heating process. The temperature distribution and residual deformations for 6 mm, 8 mm, 10 mm and 12 mm thick steel plates were numerically estimated and compared with experimental and published results. Extensive data generated through a validated FE model were used to find co-relationship between the input parameters and the resulting residual deformation by multiple regression analysis. The results obtained from the deformation equations developed in this work compared well with those of the FE analysis with a drop in the computation time in the order of 100 (computational time required for FE analysis is around 7 200 second to 9 000 seconds and where the time required for getting the residual deformation by developed equations is only 60 to 90 seconds).     

SAW焊接型剖面预报的模糊逻辑系统开发(英文)

A fuzzy model was presented to predict the weldment shape profile of submerged arc welds(SAW) including the shape of heat affected zone(HAZ).The SAW bead-on-plates were welded by following a full factorial design matrix.The design matrix consisted of three levels of input welding process parameters.The welds were cross-sectioned and etched,and the zones were measured.A mapping technique was used to measure the various segments of the weld zones.These mapped zones were used to build a fuzzy logic model.The membership functions of the fuzzy model were chosen for the accurate prediction of the weld zone.The fuzzy model was further tested for a set of test case data.The weld zone predicted by the fuzzy logic model was compared with the experimentally obtained shape profiles and close agreement between the two was noted.The mapping technique developed for the weld zones and the fuzzy logic model can be used for on-line control of the SAW process.From the SAW fuzzy logic model an estimation of the fusion and HAZ can also be developed.     

大型加强板结构焊接顺序的效果研究(英文)

Welding sequence has a significant effect on distortion pattern of large orthogonally stiffened panels normally used in ships and offshore structures. These deformations adversely affect the subsequent fitup and alignment of the adjacent panels. It may also result in loss of structural integrity. These panels primarily suffer from angular and buckling distortions. The extent of distortion depends on several parameters such as welding speed, plate thickness, welding current, voltage, restraints applied to the job while welding, thermal history as well as sequence of welding. Numerical modeling of welding and experimental validation of the FE model has been carried out for estimation of thermal history and resulting distortions. In the present work an FE model has been developed for studying the effect of welding sequence on the distortion pattern and its magnitude in fabrication of orthogonally stiffened plate panels.     

响应面法模拟轴肩和搅拌针形状对铝合金搅拌摩擦的影响(英文)

The present paper discusses the modeling of tool geometry effects on the friction stir aluminum welds using response surface methodology. The friction stir welding tools were designed with different shoulder and tool probe geometries based on a design matrix. The matrix for the tool designing was made for three types of tools, based on three types of probes, with three levels each for defining the shoulder surface type and probe profile geometries. Then, the effects of tool shoulder and probe geometries on friction stirred aluminum welds were experimentally investigated with respect to weld strength, weld cross section area, grain size of weld and grain size of thermo-mechanically affected zone. These effects were modeled using multiple and response surface regression analysis. The response surface regression modeling were found to be appropriate for defining the friction stir weldment characteristics.     

搅拌工具轴肩和搅拌头轮廓对铝合金搅拌摩擦焊的影响一对比研究(英文)

In marine application,marine grade steel is generally used for haul and superstructures.However,aluminum has also become a good choice due to its lightweight qualities,while rusting of aluminum is minimal compared to steel.In this paper a study on friction stir welding of aluminum alloys was presented.The present investigation deals with the effects of different friction stir welding tool geometries on mechanical strength and the microstructure properties of aluminum alloy welds.Three distinct tool geometries with different types of shoulder and tool probe profiles were used in the investigation according to the design matrix.The effects of each tool shoulder and probe geometry on the weld was evaluated.It was also observed that the friction stir weld tool geometry has a significant effect on the weldment reinforcement,microhardness,and weld strength.