جستجوی مقالات مرتبط با کلیدواژه "fsw" در نشریات گروه "فنی و مهندسی"

Temperature prediction is essential for assessing the state of stresses, strains, and material flow during friction stir welding (FSW). In this context, the thermal and mechanical behavior of the AA6063-T5 aluminum alloy was simulated in FSW. This research utilized the Finite Element Method (FEM) for thermal and mechanical simulations, employing Abaqus/Explicit software. The first simulation focused on the thermal model, implemented through coding in FORTRAN using the Schmidt-Hotel reference model, which investigates the temperature distribution of the alloy. The second simulation was mechanical in nature; it utilized the output results from the thermal simulation to examine the stresses resulting from the FSW process. The samples were made of the same material and were butt-jointed for the operation. A tool speed of 60 mm/min, a force of 4000 newtons, and a coefficient of friction of 0.4 were applied during this process. The parameters for thermal conductivity, specific heat, coefficient of expansion, and Young's modulus were defined as temperature-dependent. The results indicated that the temperature distribution diagram at a specific point along the welding path closely matched practical examples of the FSW process. The temperature distribution contours at the beginning, middle, and end of the welding path, as well as the temperature distribution across the cross-sectional surface of the weld in the middle of the piece, were consistent with the samples. Additionally, the diagram and contour of the longitudinal residual stress in the workpiece aligned well with the completed samples.

Friction Stir Welding (FSW) is a welding technique that has brought significant advancements to the field of metal joining. An innovative variation of this technique is known as bobbin tool friction stir welding (BTFSW). This study aimed to compare various aspects, including force, temperature, and strain, between FSW and BTFSW. For this reason, the finite element method was employed, utilizing the Eulerian technique to model the welding process. The findings revealed that the presence of two shoulders in BTFSW enhances heat generation by increasing the contact area with the workpiece, resulting in improved frictional heat production. The advancing side of the BFSW sample exhibited the highest recorded peak temperature, reaching 532°C. On the other hand, the CFSW sample displayed a comparatively lower peak temperature of approximately 347°C. The elevated temperature in BTFSW enhances material flowability and plasticity, leading to reduced longitudinal forces compared to FSW. In CFSW, the longitudinal force varies between 3500 N and 2500 N, whereas in BTFSW, the longitudinal force is significantly lower, approximately 800 N. Furthermore, analysis of strain distribution demonstrated that BTFSW exhibits an hourglass-shaped strain pattern, indicating a larger area affected by strain when compared to FSW. These results highlight the benefits of BTFSW in terms of enhanced heat generation, reduced forces, and a larger strain-affected area, underscoring its potential as a superior welding technique.

This study aimed to investigate the influence of rotational and traverse speeds on the friction stir welding (FSW) of aerospace-grade aluminum alloys. To achieve this, a thermo-mechanically coupled 3D finite element analysis (FEM) was employed to analyze the impact of these speeds on temperature and strain. Additionally, tensile tests were conducted on welded joints fabricated using varying tool rotational and traverse speeds to examine the effects of welding speed on the tensile properties of the specimens. The results revealed that high welding speeds had a detrimental effect on the mechanical properties of the weld samples. Samples produced using an optimal rotational speed of 1200 rpm and a traverse speed of 40 mm exhibited a tensile strength of 346 MPa, which accounts for approximately 64% of the strength seen in the base material.

Friction Stir Welding has significantly transformed the metal joining industry, and an innovative variation known as stationary shoulder FSW has emerged. This study aimed to compare various aspects, including force, temperature, and strain, between conventional friction stir welding (CFSW) and stationary shoulder friction stir welding (SSFSW). To accomplish this, the finite element method was employed, utilizing the lagrangian technique to model the welding process. The findings revealed that in SSFSW, the highest temperature was observed in the vicinity of the rotating pin. This was attributed to the absence of a rotating shoulder in SSFSW, which played a major role in heat generation during welding. Moreover, the longitudinal forces on the tool in SSFSW were significantly higher compared to CFSW, approximately ten times greater. In the CFSW process, the affected area showing strain usually forms a basin-shaped pattern. However, in the SSFSW process, the strain distribution is confined within the range of the tool pin.

This study investigates the mechanical properties, microstructure, and fracture behavior of friction stir welded (FSWed) AA7075 joints considering the influence of process parameters and tool geometry. FSWed joints are produced with a conical pin and conical threaded pin type tools using tool rotational speeds of 1400 and 2000 rpm and welding speeds of 20 and 40 mm/min. The FSWed joint showed higher values of the tensile strength (188 MPa), percentage elongation (5.7%), and microhardness (137 HV) with the conical threaded pin type tool. However, the conical pin type tool produced a minimum surface roughness of 9.59 μm. A comparatively lower tensile strength observed for the FSWed joint with conical pin type tool could be attributed to their coarser, elongated, and heterogeneous grain distribution and porosity defects in the welding zone. No significant difference has been observed in the microhardness with the conical pin and conical threaded pin type tools. The fracture of the FSWed joint predominantly occurred in the heat-affected zone during the tensile test. The FSWed joint produced with a conical threaded pin showed better mechanical properties, favorable microstructure, and ductile type fracture behavior at a welding speed of 40 mm/min and tool rotation of 2000 rpm.

The present manuscript focuses on developing a mathematical model to predict the intergranular corrosion rate of friction stir welded AA5086 H32 aluminium alloy joints. Six factors-Five levels central composite design matrix, having 52 experiments, is used for design of experiments. The developed model is used to examine the impact of studied process parameters i.e. rotational speed, welding speed, tool shoulder diameter, tool hardness, tilt angle , and pin profile on intergranular corrosion rate of the welded joints. Response surface methodology is used to optimize the process parameters for minimizing the susceptibility to intergranular corrosion attack. The optimum combination of studied parameters, to have minimum corrosion rate i.e. 3.2 mg/cm2, is obtained as 1296 rpm rotational speed, 79.4 mm/min welding speed, 14.9 mm tool shoulder diameter, 47.4 HRC tool hardness, 2.380 tilt angle, and square pin profile.

In the present study, parameters of tool rotation speed, tool travel speed and tool offsetting with different levels were used in the friction stir welding (FSW) of aluminum-copper tailor welded blanks (TWBs). The FSW of pure copper to 5052 aluminum alloy were carried out by varying tool rotation speed from 800 rpm to 1200 rpm, tool travel speed from 40 mm/min to 80 mm/min and tool offsetting from 1 mm to 2 mm. The L9 orthogonal array of Taguchi was used to design 9 experimental tests and each test was repeated three times. The uniaxial tensile test based on the ASTM-E8 was used for mechanical properties extraction of TWBs. The tool rotation speed of 1200 rpm, tool travel speed of 60 mm/min and tool offsetting of 1.5 mm resulted in the optimum range of heat input to form a stir zone with good quality. Using these FSW parameters caused the formation of thin intermetallic layers which stopped the motion of dislocation in the tensile test and resulted in higher tensile strength and joint quality. The scanning electron microscope (SEM) was used to scan the tensile fracture surface of TWBs.

Formability of automotive friction stir welded TWB (tailor welded blank) sheets is numerically investigated in biaxial stretching based on hemispherical dome stretch (HDS) test in four automotive sheets of Aluminum alloy 6111-T4, 5083-H18, 5083-O and DP590 steel, having different thicknesses. The effects of the weld zone modeling and the thickness ratio on formability are evaluated. In order to carry out the numerical simulations, mechanical properties are considered according to Chung et al. [11] experimental results. von-Mises and Hill’48 quadratic yield functions are used to compare the isotropic and anisotropic behaviors of the used sheets. In order to simplify the problem, the anisotropy of the weld zone is ignored. The FEM results are compared with experimental results of [11]. Anisotropic assumption for base materials and varying thickness for the weld zone give more accurate prediction. Numerical results are in good
agreement with the experimental results. Failure onset locations and patterns are accurate. Since the formability is dependent on the stress concentration, asymmetric distribution of strength and complexity of weld zone properties, the thickness ratio in TWB affect formability.