Papers by Keyword: Axial Force

Abstract: This research investigates the influence of friction stir welding (FSW) parameters on the axial force and mechanical properties, specifically: ultimate tensile strength and Vickers hardness, of AA6061-T6 aluminium alloy using Taguchi experimental design. The study explores various combinations of four factors: rotation speed, welding speed, dwell time, and preheat temperature, each factor with three levels and two replicated, resulting in 18 experiments. The FSW experiments conducted using a CNC machine with parameters derived from the Taguchi experimental design yielded a maximum ultimate tensile strength of 295.66 MPa and a peak Vickers hardness of 81.32 HV. Dynamometer measurements indicated that an average axial force of approximately 2 kN during the welding process produced the most favorable ultimate tensile strength results. Moreover, an analysis of the factors using the Taguchi experimental method, focusing on the signal-to-noise ratio, indicated that to achieve the highest response values, the levels of the factors should be adjusted as follows: a rotation speed of 1250 rpm, a welding speed of 900 mm/min, a dwell time of 20 seconds, and a preheat temperature of 200°C.

Abstract: The friction stir welding (FSW) process has gained popularity in joining various types of aluminum alloys. The heat generated during the process is caused by the friction between the shoulder of the welding tool and the workpiece. The axial force (Fz) of the weld plays a crucial role in the welding process. If the axial force is insufficient to generate heat will result in defective workpieces. Therefore, the aim of this study was to predict the axial force of the FSW process of dissimilar aluminum alloys (AA7075-T6 and AA2024-T3) using machine learning techniques. The data used to create the predictive model was obtained from experiments involving 5 factors, each with 2 levels: 1) welding speed (mm/min), 2) rotational speed (RPM), 3) type of tools, 4) plunge depth (mm), and 5) dwell time (sec). The axial force was measured using a dynamometer with a sampling frequency of 10 Hz. The predictive model was created using all 4 algorithms: AdaBoost, CatBoost, LightGBM, and XGBoost. The performance of the four predictive models was evaluated using four metrics: mean absolute error (MAE), mean absolute percent error (MAPE), mean square error (MSE), and root mean square error (RMSE). The results showed that the AdaBoost algorithm had the best performance, with MAE, MAPE, MSE, and RMSE values of 509.08, 0.24, 452591.73, and 672.75, respectively. The AdaBoost algorithm was then used to predict the axial force using a dataset of 29,282 data, with predicted minimum average axial force of 1871.6 N. When compared to the axial force measured in the experiment, which was 1265 N, the results showed that the AdaBoost algorithm was capable of predicting the axial force with acceptable accuracy.

Abstract: Friction stir welding (FSW) has become very popular for joining similar or dissimilar aluminum alloys. The heat used for this welding process is caused by friction between the welding tool and the workpiece which the axial force, the main parameter for heat generation, plays a very important role. Insufficient heat during welding will result in defective workpieces. This research is aimed to predict the axial force from the relevant factors of the FSW of dissimilar materials (aluminum alloys AA2024-T3 and AA6061-T6). The 2³ full factorial design with center point was used for this experiment that consisted of 3 main factors: 1) rotation speed (rpm), 2) welding speed (mm/min), and 3) pin geometry each factor has 2 levels and 2 replications with the total of 20 experiments. The axial force data of each experiment were collected using a stationary dynamometer which obtained the data acquisition every 0.1 seconds (frequency of 10 Hz). The results from the design of experiment were analyzed by statistical method at the significance level of α = 0.05 which found that the significance and the optimum value of the main factors were rotation speed of 1500 rpm, welding speed of 35 mm/min, pin geometry of tri flat threaded, and the 2-way interaction between rotation speed and pin geometry. Furthermore, the prediction of the average axial force value on dissimilar aluminum alloys obtained from the specified parameters equals 478.91 N.

Abstract: Concrete segments are widely used to support soil and water loadings in shield-excavated tunnels. Concrete segments burden simultaneously to the loadings of bending moments and axial forces. Based on plane deformation assumption of material mechanics, in which plane section before bending remains plane after bending, ultimate bending moment model is proposed to compute ultimate bearing capacity of concrete segments. Ultimate bending moments of concrete segments computed by analytical models agree well with numerical simulation results by FEM. The accuracy of proposed analytical computational model for ultimate bending moment of concrete segments is numerically verified. The analytical computational model and numerical simulation for a practical engineering case indicate that the ultimate bending moment of concrete segments increases with increase of axial force on concrete segment in the case of large eccentricity compressive state.

Abstract: Experience gained in design, erection and operation of span reinforced concrete structures has proved that practically all of them are subject to complex stress-strain state. At that, the researchers pay considerable greater attention to calculation of strength, deformation analysis and determination of crack resistance in normal cross-sections than to calculation of their support zones, including oblique sections, which results are generally taken into account for determining the section dimensions and the quantity of the cross reinforcement.

Abstract: This paper presents boundary conditions for lateral buckling of the H-shaped beams connected to columns by flush end plates which fall into the lateral buckling following the out of plane plastic deformations of the flush end plates. The study is conducted by the following procedure: First, the behavior of the connection is researched by the no buckling experiment under the cyclic loading. As a result, it is found that the relationship between the out of plane plastic deformations of the endplates and the bending moment at the beam end can be predicted. Next, the FEM analyses of the rigid-frame structures consist of the slender beams having flush end plates connection and the structures consist of the beams having rigid connection are conducted to research the stress conditions in the tension flanges and the compression flanges of the beams during falling into lateral buckling. As a result, it is found that the rigid connection is restraining warping of the beam more tightly than the flush end plates connection, then the maximum bending moment strength against lateral buckling of the beams connected by rigid connections is higher than those of the beams connected by flush endplate. We recommend that the boundary conditions for the lateral buckling of the beams connected by flush end plates should be regarded to be different from those of the beams connected by the rigid connections.

Abstract: Friction stir welding (FSW) is one of the new technique for welding materials in solid state welding process. In this proposed work we are using FSW to join the two dissimilar alloys of aluminium. The 6mm thick aluminum plates of aluminium 5086 and aluminum 7075 plates are considered for welding. These have been considered due to their application in various fields. In this experimental process Taguchi’s L9 orthogonal array method is used for optimizing the three process parameters namely rotational speed, axial force and welding speed. To produce a better joint the tensile strength is predicted for the optimum welding parameters and also their percentage of contribution is calculated, by applying the effect of analysis of variance. Depends upon the experimental study, the rotational speed is found better over the other process parameters, which enhances the quality of the weld. The tensile strength has been found for the optimum parameters and the result found during the experiment was 290Mpa which was higher than the base metal strength of aluminium 5086 alloy. The SEM fractograph analysis was done on the optimum parameters welded joints to show the fracture behaviour of tensile test which justifies the visual inspection results of brittle and ductile failures.

Abstract: This article presents an experimental investigation of the friction stir spot welding process in thin-walled plates by using a special HSS tool. A review of the literature dealing with the analyzed problem was conducted and the experimental setup for FSSW experiments was described. The experiments were carried out on non-ferrous 5754 aluminum alloy, copper M2 and brass CuZn37. Variations of experimental axial force were obtained.

Abstract: This paper briefly describes the principle of the ultrasonic single point incremental forming of the sheet metal. In which we established the finite element model and finished the finite simulation with ABAQUS. According to the simulation result, we analyzed the influence law of vibration frequency of the axis on the distribution of the stress and strain of the sheet metal, the thickness, and the axial force in the process of ultrasonic single point incremental forming of the sheet metal. The result shows that the influence on the stress and thickness of the sheet metal is minimal, and the influence on the strain follows the law of cosines in which the strain is minimum when the vibration frequency is equal to 15kHZ.The influence on the axial force is that when the frequency is f=0kHz～40kHz the axial force decreases with the increase of the frequency. However, the axial force increased dramatically with the increase of the frequency when the frequency is above 40kHz.

Abstract: Aluminum alloys exhibit poor weldability by conventional fusion welding process. The heat treatable aluminum alloy AA2014 is extensively used in the aircraft industry because it has good ductility and high strength to weight ratio. In this paper the effects of welding parameters and tool profile on the mechanical properties of friction stir welded butt joints of dissimilar aluminum alloy sheets AA6082 and AA2014. The process parameters such as rotational speed, transverse speed and axial forces were considered. The effect of parameters on weld quality was analyzed. Hardness and tensile tests are carried out at room temperature to examine the mechanical properties of the welded joints. The joints produced with straight square tool pin profile have higher ultimate tensile strength, whereas the straight cylindrical tool pin profile results in lower tensile strength.