Current Issue : January - March Volume : 2020 Issue Number : 1 Articles : 5 Articles
A novel systematic framework, infrared thermography- (IRT-) based method, for rotating machinery fault diagnosis under\nnonstationary running conditions is presented in this paper. In this framework, IRT technique is first applied to obtain the\nthermograph. Then, the fault features are extracted using bag-of-visual-word (BoVW) from the IRT images. In the end, support\nvector machine (SVM) is utilized to automatically identify the fault patterns of rotating machinery.The effectiveness of proposed\nmethod is evaluated using lab experimental signal of rotating machinery. The diagnosis results show that the IRT-based method\nhas certain advantages in classification rotating machinery faults under nonstationary running conditions compared with the\ntraditional vibration-based method....
Friction welding is a solid-state bonding process that presents itself as an interesting option as it generates less residual stress, less\ndistortion, and crack formation when compared to the fusion welding process. The characteristics of this process also allow\nsatisfactory welding of dissimilar materials, with good results in terms of mechanical strength. In this work, the butt welding of\naluminum ASTM A6351-T6 and SAE 1020 steel was carried out aiming at evaluating the effects of the initial contact geometry on\nthe mechanical properties of the welded joint. The methodology consisted of friction weld aluminum bars with different initial\ncontact geometry with steel bars in a machine specially developed for the application. The results indicated the influence of this\nparameter on the mechanical properties of the welded joint....
The advantage of selective laser melting (SLM) is its high accuracy and geometrical flexibility.\nBecause the maximum size of the components is limited by the process chamber, possibilities must be\nfound to combine several parts manufactured by SLM. An application where this is necessary, is,\nfor example, the components of gas turbines, such as burners or oil return pipes, and inserts, which can\nbe joined by circumferential welds. However, only a few investigations to date have been carried out\nfor the welding of components produced by SLM. The object of this paper is, therefore, to investigate\nthe feasibility of laser beam welding for joining SLM tube connections made of nickel-based alloys.\nFor this purpose, SLM-manufactured Inconel 625 and Inconel 718 tubes were welded with a Yb:YAG\ndisk laser and subsequently examined for residual stresses and defects. The results showed that\nthe welds had no significant influence on the residual stresses. A good weld quality could be achieved\nin the seam circumference. However, pores and pore nests were found in the final overlap area,\nwhich meant that no continuous good welding quality could be accomplished. Pore formation was\npresumably caused by capillary instabilities when the laser power was ramped out....
In designing a horizontal directional drilling (HDD) pipeline project, designers\nface the challenge of determining the regions of maximum and minimum stresses\non pipelines, ensuring the stability of the bore-hole from collapse and minimizing\nthe stresses induced on the pipeline due to the bore-profile. This study analyses\nthe stress induced on an HDD pipeline system using the ANSYS Version\n18, mechanical APDL finite element (FE) software. The pipeline used as the case\nstudy was a gas transmission pipeline installed in south-west Nigeria. A macro-\nfile for ANSYS Version 18, mechanical APDL used to model the pipeline\nwas developed. The results showed that the maximum and minimum stresses\ninduced on the HDD pipeline were at the top and bottom of the pipe, respectively;\nwhile the stresses on the sides were uniform (Approximately equal to 888 kg/cm2) all through the\npipeline, irrespective of element number. The maximum stress occurred at the\ncurvature point with the highest entry angle (10 Angstrom), resulting in a maximum deflection\nat this point. The model stress validation performed by comparing results\nwith theoretical solutions, both with respect to radius of curvature and internal\npressure, showed percentage difference (errors) less than 10%. The cross sectional\narea validation showed a percentage difference of 0.059%....
A multi-strand composite welding wire was applied to join high nitrogen austenitic\nstainless steel, and microstructures and mechanical properties were investigated. The electrical\nsignals demonstrate that the welding process using a multi-strand composite welding wire is highly\nstable. The welded joints are composed of columnar austenite and dendritic ferrite and welded\njoints obtained under high heat input and cooling rate have a noticeable coarse-grained heat-affected\nzone and larger columnar austenite in weld seam. Compared with welded joints obtained under the\nhigh heat input and cooling rate, welded joints have the higher fractions of deformed grains, high\nangle grain boundaries, Schmid factor, and lower dislocation density under the low heat input and\ncooling rate, which indicate a lower tensile strength and higher yield strength..........................
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