The article presents a study on the effects of ultrasonic treatment on residual Welding stresses (RWS). Ultrasonic treatment was administered from three orientations: external, internal, and bilateral. Six samples, each with a thickness of 8 mm and composed of steel grade 09G2S, were prepared. The Welding of these samples was executed using semi-automatic equipment and adhered to regulatory and technical guidelines. The magneto anisotropic technique, foundational to the operation of the Stress Vision Lab device, was employed to measure residual stresses. Given that this device quantifies residual stress values in arbitrary units, a calibration table was devised to translate these measurements into megapascals (MPA). This calibration was established by correlating values obtained from the ZW-100 testing machine with those measured by the Stress Vision Lab, necessitating the preparation of three additional samples of the same steel grade. Experimental investigations revealed that ultrasonic treatment applied internally to the samples facilitated the most significant Reduction in residual (tensile) stresses, with Reductions of 37.5% from external application and 27% from internal application. Leveraging the data acquired, a device has been developed to mitigate residual Welding stresses within the inner wall of the near-seam zone of pipelines.

Friction stir spot Welding has been considered as one of the superior manufacturing processes with various applications which nowadays draw the attention of aerospace industries. The main goal of the current study is to compare the shear tensile-shear strength of dissimilar aluminum alloy sheets of 7075-T6 and 2024-T3 in the friction stir spot Welding process with the riveting process commonly used in the wing and body structures of the aircraft. In addition, the influence of various parameters such as the influence of tool penetration speed, tool rotational speed, and the arrangement of aluminum alloy sheets on the tensile-shear strength of the joining zone have been investigated and compared with that of rivet joining process. By properly choosing these parameters, the optimum tensile-shear strength of the joint can be attainable. Results obtained during the current research can be considered to replace the riveting process with the stir spot Welding process in the aerospace industries, and in particular for some portions of the wing and body of the aircraft in order to achieve higher strength for the desired joints. As a result, the damage related to the joints used in aircraft structures could be efficiently reduced.

Welded tubular joints are widely used in various industry structures for high efficiency subjected to pressure, bending and twisting. Welded structures are the main parts of structures, buildings, bridges, gas pipes, pressure vessels and power transmission equipment in the ship building, construction, oil, gas, petrochemical industries and power plants. A sample of pipe-welded joints is a X-tubular joint that has been investigated in this study. The main objective of the present work is to investigate the heat transfer and residual stress caused by the three-stage Welding process in Xtubular joint made of St52 using Simufact Welding software. The Welding process involves three Welding steps using arc Welding. The finite element model contains the thermal and mechanical properties of base metal and Welding metal as a function of temperature. Also, advanced modeling tools such as mesh adaptation during the process and meshing compatible with the Welding site, the birth and death technique of the element and the source of heat transfer have been used. Welding simulation showed that significant residual stresses were created in the joint after Welding. Comparison of the results shows that the numerical results and empirical measurements are in good agreement with each other and the existing model can provide a good prediction of temperature distribution and stress control in this Welding process.

Inertial Navigation System (INS) is one of the navigation systems widely used in various land-based, aerial, and marine applications. Among all types of INS, Microelectromechanical System (MEMS)-based INS can be widely utilized, owing to their low cost, lightweight, and small size. However, due to the manufacturing technology, MEMS-based INS suffers from deterministic and stochastic errors, which increase positioning errors over time. In this paper, a new effective noise Reduction method is proposed that can provide more accurate outputs of MEMS-based inertial sensors. The intelligent method in this paper is a combined denoising method that combines Wavelet Transform (WT), Permutation Entropy (PE), Support Vector Regression (SVR), and Genetic Algorithm (GA). Firstly, WT is employed to obtain a time-frequency representation of raw data. Secondly, a four-element feature vector is formed. These four features are (1) amplitude of frequency, (2) its ratio to mean of amplitudes of all frequencies, (3) location of frequency in time-frequency representation, and (4) judgment on behaviors of frequency that is obtained by utilizing PE. Thirdly, based on the feature vector, the GA-SVR algorithm predicts amplitudes of all frequencies in the time-frequency representation of the denoised signal. Finally, by employing inverse WT the denoised signal is obtained. In this work, the outputs of the Inertial Measurement Unit (IMU) in ADIS16407 sensor, as a low-cost and MEMS-based INS, have been utilized for data collection. The proposed method has been compared with other noise Reduction methods and the achieved results verify superior improvement than other methods.

Residual stress is one of the most substantial defects of welded parts caused by intensive thermal gradient. In this study, different mechanical and thermal techniques for reducing residual stresses have been investigated and the effectiveness of contributing parameters has been discussed afterwards. Subsequently, some equations have been proposed for Welding energy and exergy efficiency and the effects of parallel flame heating, vibration method, and hammer working method on reducing Welding residual stresses are expressed. The results show that by using parallel heating technique, the enhancement of flame power would result in reducing both energy and exergy efficiencies. However, the decremental rate of the two efficiencies would slow down and they approach to an asymptotic value. Increasing the speed of Welding improves two efficiencies more than 2 times. On the other hand, the normalized entropy is reduced by increasing the heat input of the flames. This fact is an indicator of a Reduction in Welding residual stress. This Reduction is more at high speeds. Eventually, the ratio of the two efficiencies shows that in this study, economical power was about 1800j/s. The Reduction of normalized entropy for the vibration, hammering, and parallel flame methods are 0. 001, 0. 1, and 10, respectively. Overall, it is expected that thermal methods are more efficient than mechanical methods in reducing residual stresses.

In Welding process, stresses after cooling, which remain in body, are called residual stresses. Sometimes, the magnitude of stresses is high and reduces the strength of welded pieces, moreover, they cause crack in the weld. To predict Welding residual stresses, it is necessary to do thermal and mechanical analysis.In this paper, some parameters which influence the Welding using ANSYS software are investigated. Results show that even by decreasing the travel speed of torch, it makes no differences in the amount of residual stresses, but preheating causes decreasing the produced stresses about 22 percentages. Suitable Welding sequences also, decreases residual stresses up to 25 percentages.

Friction stir Welding (FSW) can be defined as a green technology, because the consumption of energy during this process is less than other Welding methods. In addition, during the process there is no gas, filler material or other consumables. It should be noted that, complex curved shapes are now commonly used in different industries in a bid to have lightweight structures. According to the above-mentioned descriptions, several investigations into the potential benefits of adopting Friction Stir Welding (FSW) in the production and joining different materials are being undertaken. The work presented in this paper is focused on thermal behavior of the curved FSW and its benefits for the green technology. Due to the robust nature of FSW process aluminum 6061-T6 alloy has been selected as the Welding material. The results of the study showed that, the total peak temperature value of 300° C happened at time, t = 3 s at the plunge stage (outside of the Welding seam). Meanwhile, at the dwell stage (between t = 3 s to t = 5 s), there is a stable situation in the amount of the generated heat from the plastic deformation as well as the contact shear stress at the tool-workpiece contact interfaces, thus the interfacial temperature is found to be stable. By the end of the dwelling step, the total generated heat is stable to the maximum value of 300° C. At the step time of t = 12. 8 s, the temperature is distributed asymmetrically across the workpiece until the time step of 19. 6 s which at this point the asymmetric contour expanded in the stir zone.