Papers by Keyword: Repairing

Abstract: TBCs (Thermal Barrier Coatings) are multilayer structures usually consisting of a ceramic layer, known as top coat, arranged on a connecting layer, known as bond coat, which, in turn, is arranged above the substrate to protect. These structures are applied in hot section parts of gas turbine engines for providing thermal protection. During the component life, some oxidation end/or wear phenomena can occur, therefore the TBC is generally removed and then reapplied. To simplify the manufacturing process making it more cost effectiveness, the aim of this work is to study the possibility to repair a TBC system by removing the only damaged layer by using non-conventional processes and analyzing in detail the morphological roughness to ensure a good adhesion between the layers.

Abstract: Friction stir welding (FSW) consists formation of keyhole at the end phase of the process, which is major defect and needs to be removed. In the present investigation, keyhole of dissimilar friction stir welded Al-Mg joint was repaired by novel technique of pin less tool friction stir repairing. Two different pin less tools having different tool diameters were applied to repair keyhole. Visual inspection, macro structural analysis, microstructure features and mechanical properties are assessed in order to check the successful prevail over of keyhole defect. The results revealed that, keyhole of dissimilar friction stir weld of Al-Mg joint was effectively repaired by pin less tool friction stir repairing. Excellent material mixing was obtained in the repaired area of keyhole. Tensile strength was obtained as 159 MPa that was higher than the dissimilar Al-Mg FSW joint.

Abstract: Direct metal lamination using arc discharge was applied to the repair of metal components such as metallic parts, dies and molds by adding equivalent metal to them. In this method, a heat-affected zone which has different mechanical properties from the base metal is formed near the laminated metal. This is because the rapid temperature change by welding heat input can cause phase transformation or metallic structure change. Therefore, the mechanical properties of the laminated metal, heat-affected zone and base metal after repair by direct metal lamination need to be explored. In addition, the region which needs to be repaired must be removed in advance because worn and defective parts aren’t adequate as the base for lamination of further layers. Thus, the most suitable removal shape for repair by direct metal lamination was investigated. Finally, the hardness distribution and toughness of the metal components after repair was explored. It was found that the hardness distribution of metal components after repair was uneven. However, the toughness of the heat-affected zone was found to be comparable to those of the laminated metal and the base metal.

Abstract: It can not be avoided that composite blade may be damaged duiring using. The detecting and repairing methods of helicopter composite blade damage, and the experiment after repair are introduced in this paper. The technique problems in detecting and repairing of helicopter composite blade damage are solved.

Abstract: Repairing of past earthquake-damaged members that are highly susceptible to future attack is necessary to prevent civil infrastructure destruction and consequent lives lose.Sprayed basalt FRP composite was tested and presented here as a promising solution.In this study, three 1/2 scaled reinforced concrete frame columns were used to investigate the effectiveness and feasibility.One column was damaged to failure and used as a reference specimen.The other two columns were damaged up to the yielding of main bars simulating deterioration of the structure due to seismic action to a control level.These two columns were repaired with sprayed basalt fiber reinforced polymer (BFPR) composite.Different thicknesses of sprayed BFRP composite were applied.Each specimen was subjected to lateral low-frequency cyclic loading and simultaneous constant axial load to simulate seismic action and dead load respectively.The test result analysis showed that sprayed BFRP can increase the load carrying capacity, enhance the energy absorption capacity, and can effectively restore the strength of past earthquakedamaged RC column.

Abstract: This paper introduces coal mine single hydraulic prop repairing actuality and a type of Special disassembly machine using to disassemble single hydraulic prop. Describes the main components of the machine, it have the main motor, reducer, rotating hydraulic chucks, remove column cylinder, fixed hydraulic clamp, disassembly valve device. Discuss its composing structure, work principle, machine process, main specialty, the technical problem what this machine can solve and using this machine for attainability purpose. Point out its advantage: operation convenience, reduce the labor intensity of workers, saving auxiliary time, increasing efficiency, reducing shock and prolonging life.

Abstract: The cause of cracks after brush-plating on the main speed reducer of helicopter was analyzed and the ameliorative measures by shot-peening were brought forward consolidation. The measure, the components of plating liquid and the master parameters of working procedures were itemized, which can apply to renovation of accessory’s abrasion and scars in the situation of big alternant load.

Abstract: Using BFRPS to increase strength and durability of the structure has recently started to be used as a new technical mean. In this paper, eight BFRPS timber columns under axial compressive loads are tested, and damage characteristics and mechanical properties are studied based on the testing results. Compared with the components which are reinforced and not, the relationship between the effects of bearing factors and increasing degrees can be concluded, providing reference for the similar engineering problems.

Abstract: Aiming at repairing aluminum alloy wear-out parts, the multiple compound metallic-membrane plating is researched with anodic oxidation, chemical plating Ni-P and later heat processing, blacken processing. Experiments show that this plating has many advances such as lower porosity, stronger binding force, higher hardness, better corrosion and abrasion resistant, another, this method of repairing only needs simple condition and is easy to be operated, this technology of repairing provides a new method for repairing of aluminum alloy wear-out parts.

Abstract: In this paper, using experimental method studied to repair surface fatigue damage of the metal material by heat treatment. Analyzed the mechanism to repair surface fatigue damage of the metal material by heat treatment. From the test, it have been found that the Metal materials has temping threshold behavior in repairing it’s fatigue damage by heat treatment. For the same kind of material, there is a threshold characteristics in choosing tempering temperatures when repaired the fatigue damage of metal material surface through changed tempering temperatures. Experimental results shows that the temping temperature threshold to repair metal material fatigue damage is the first tempering temperature after materials was hardened before it was in fatigue damage.