Zoia Apostolescu

Ultrasonic System Design and Calculation for Polymer Metallization

Paper presents ultrasonic system design and calculation for metallization process of the polymer pieces. Because of some bad properties like: very low hardness, very low wear resistance, no electrical conductivity and no open fire resistance, polymer parts has to be reinforced with different materials. A new method is represented by ultrasonic field metallization process which has certain advantages. The work presents the analytic calculation for the ultrasonic field and vibration modes of the ultrasonic system used for a polymer base material ultrasonic activation.

Fatigue FEM analysis in the case of brazed aluminium alloy 3L59 used in aeronautical industry

The use, on a larger scale, of brazed aluminum alloys in the aerospace industry led to the need for a detailed study of the assemblies behavior. These are built from 6061 aluminum aloy (3L59) brazed with aluminum aloy A103. Therefore, a finit element simulation (FEM) of durability is necessary, that consists in the observation of gradual deterioration until failure. These studies are required and are previous to the stage of the producing the assembly and test it by traditional methods.

Contributions regarding chemical composition variation in ultrasonic field overlaying welding

Paper presents a new reconditioning method based on ultrasonic field and analyses the modificated structure composition in three zone: filler material, thermal influenced zone, and base material. Also, chemical composition variation as a result of ultrasonic wave influence is studied besides the ultrasonic wave influence on dilution process.

Studies and research on the microstructure of brazed aluminum alloys in the repair process

In aeronautical industry, in recent years, brazing joints got a growing spread. Therefore, it is necessary a detailed study on the microstructure of the assembly base and filler material brazed in conditions of reconditioning operation [1]. The methods of destructive examination are not associated with any particular type of test piece but lay down the general principles of the types of testing described. It is emphasized that a satisfactory examination method can only be developed and used after taking into account all the relevant factors regarding the equipment to be used and the characteristics of the test pieces being examined. [1, 2]. Brazing joints are most often systematically designed to be resistant to shearing, and the size of the joint influences the shear strength more than the tensile strength. Studies and researches on the microstructure may be necessary to determine the effects of brazing process or of any subsequent heat treatment on the characteristics of the joint.

Contributions to the Environmental Impact of the Process of Welding Work in the Environment of Protective Gases

Paper presents the main pollutants that appear Gas metal arc welding, the main chemical reactions take place in the melting bath where results the pollutants, determining the impact on the working environment by calculating the coefficient of pollution. The optimization of welding process gives a coefficient of minimum pollution and determines the influence of welding parameters of the system on the appearance of major pollutants elements.

Theoretical and Experimental Cladding Technological Process of Spare Mechanical Engineering

The paper presents the process of cladding surfaces required strong corrosion of parts in the chemical, petrochemical and engineering industry. The phenomenon of the factors that influence the dilution that occurs between the filler material and the base material and the technological processes possible to achieve efficient plating. Following technical and economic analysis establishes that process arc welding argon environment is a process that can be used optimally to plating. It presents experimental results obtained after plating surfaces of parts of the petrochemical industry, the functional characteristics of materials resulting torque in all three major areas (base material, heat affected zone and weld material), structural analysis and possible defects that may occur after the plating process.

Experimental Results Regarding Metal Plating by Welding Method in Ultrasonic Field for High Corosed Base Metal Piece

Paper presents necessity of metal plating in the case of highly corosion process acting on metal pieces. By authors researches, the welding plating method has some disadvantages, possible to be eliminated by using the ultrasonic field. The work presents a series of experimental results obtained in the case of metal plating using welding method [10] with or without ultrasonic field. There were analised the main coupled material resulted functional properties and the final microstructure in the distinctive zone: base material, thermal influenced zone, and addition material.

Influence of the Milling Weld Toe and WIG Remelting Reconditioning Technology to Welded Pieces in the Case of Fatigue Testing

The paper presents the researches to determine the best technologies to improve the lifetime of the corner welding. Generally it is says that the convex corner welding presents high mechanical properties because of the greater area section. The practice activity shows that in fact, because of the stress concentrators, these shapes of the welding are not the best solution. A better shape of the corner welding is the concave one that provides better results in the working conditions. To provide better results of the convex shape corner welding different recondition techniques are known. The paper is focused on fatigue testing performed on different samples realized with different beads on different working parameters. There are studied different reconditioned probes and the results are reported in fatigue curves.