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.

This work exploits the concentrated loading method (C.L.M) for the evaluation of woven fabric Formability. A total of 21 randomly selected woven fabrics are tested by Lindberg and C.L.M methods and the results are compared. The correlation between calculated Formability (bending rigidity/low initial modulus) and the measured features extracted from the concentrated loading curves indicates the possibility of measuring of Formability of woven fabrics by C.L.M. Among the features extracted from the concentrated loading curves, the initial slope of the load extension curve (IS), the ending slope of the unloading curve of the concentrated loading method (ES) and the gap area below the buckling (GABB) are highly correlated to the calculated Formability of the fabrics. The correlation results indicate that testing the fabric samples under C.L.M can be used for direct estimation of the Formability of the woven fabrics without requiring two different laboratory testers (bending and tensile).

Formability of Tailor Welded Blank (TWB) is an important parameter which limits this kind of blanks usage. A forming criterion for tailor welded blank is presented based on the analytical model in this research. This criterion suggests Limit Strength Ratio (LSR) and Limit Thickness Ratio (LTR) for forming limit of TWB. When thickness ratio or strength ratio in tailor welded blank is greater than LTR or LSR, Formability will be limited and necking will happen sooner. The influence of thickness ratio on the Formability of TWB has been investigated by experimental tests and Finite Element (FE) simulations, but strength ratio has just been studied by simulation. All the simulation and experiment results indicate that by the increase of thickness ratio and strength ratio, the Formability will decrease and weld line movement will increase. The obtained results of the present study indicate that fracture happens in the thinner side of TWB and near to the weld line. Moreover, fracture line is parallel to weld line and the fracture position moves farther than weld line by thickness ratio decreasing. Simulation results have a good agreement with experimental results as well.

Steel laser tailor-welded blanks (TWBs) are produced by end-to-end joining of base sheets using different welding methods. In this article, the Formability of laser TWBs of St12 and St14 with thicknesses of 1 mm and 1. 5 in single point incremental forming process were experimentally and numerically investigated. First, the forming limit wall angle was experimentally determined for each of the base sheets. Then, SPIF of TWBs samples was carried out at the thinner sheet wall angle; 67° . For numerical investigation, the mechanical properties of the weld zone were obtained. For one combination of TWBs, the finite element (FE) simulation of incremental forming was performed by the use of ABAQUS/Explicit FE software. The simulation process was validated by comparing the results with those of experiments. Then, the effect of SPIF on thickness, stress and strain distribution of other combinations of TWBs was numerically investigated. The results showed that using the FE model, the SPIF of TWBs without performing high cost experimental tests can be properly investigated. Also, the results revealed that in steel laser TWBs with different thicknesses, the maximum and minimum principal strains are concentrated at the corners and the walls of the thinner sheet of TWBs, respectively. Hence, the maximum amount of effective strain is concentrated at the thinner side of TWBs corners and the weld zone of the two blanks. For the same reason, rupture is observed at these regions.

Tube forming is a common forming process in industry. There are several methods in tube forming, whereas industries are looking for best methods with low cost and high speed. For this reason, industries need new modern forming methods. Electromagnetic forming and tube hydroforming are two modern processes which are used in manufacturing of hollow complex parts. These two processes are considered as high speed forming methods in automotive industries. In this paper, the processes of electromagnetic forming of tubes and high speed hydroforming of tubes have been investigated by numerical simulations and empirical method. Firstly, the results of numerical solutions by ABAQUS software are compared with empirical tests. At last these two forming methods have been compared in terms of displacement, stress distribution and thickness distribution. The results of deformation and thickness of the tip of the bulged tubes in empirical tests are in good agreement with the results of numerical simulations of this research. The results show that Formability and bulge height in electromagnetic forming process are higher than high speed hydroforming. However, high speed hydroforming may be used in applications such as shirring fitting of parts and rings on tubes instead of electromagnetic forming.

In this research, three-layered composite of brass-IF steel-brass was fabricated by cold roll bonding process (CRB) and Formability of composite were investigated. Due to high work hardening of composite during rolling process, specimens were heat treated at annealing temperatures at 500° Ϲ through 700 ° Ϲ for 10 min. Formability properties of composite were investigated by using tensile, anisotropy and Erichsen tests. The results showed that, heat treatment after rolling resulted in occurrence of recrystallization phenomenon in composite, consequently a reduction tensile strength and rising strain hardening rate. Dome height created by Erichsen test prior to heat treatment was 10. 53 mm, by annealing composite at 500 ℃ , Dome height reached at 14. 62 mm. By increasing annealing temperature to 600℃ and owing to relatively high stacking fault energies of IF steel, recrystallization solitary occurred in brass layer. Nevertheless, as a result of upward trend of annealing temperature up to 650 ℃ as well as resultant driving force, recrystallization occurred in all layers and gradient of Formability properties increased. As at 700℃ , recrystallization phenomenon was completed in the composite and dome height was peaked at 17. 29 mm. Moreover, by increasing annealing temperature, normal anisotropy and planer anisotropy respectively increased and decreased. Anisotropy properties of composite in comparison with brass and IF steel during complete recrystallization, it was clear that production of brass-IF steel-brass composite caused to improve normal anisotropy in brass and reduce negative effects of planer anisotropy in IF steel.

Magnesium alloys offer many advantages. They offer the very low density and good strength. They also offer good damping properties. One of the industries where reducing component weight in the automotive industry. That makes the magnesium alloys good candidates for these applications. Reduced weight of an automobile means also lower fuel consumption. The hexagonal closed packed structure of magnesium lends itself to strong mechanical anisotropy. In the current work, neutron diffraction was used to study the crystallographic texture developed in novel magnesium alloys during cold rolling operations. The texture was compared with that developed in the commercial AZ-31 magnesium alloy. Tests were run at the High-Pressure-Preferred-Orientation (HIPPO) beamline at Los Alamos National Lab. The texture was then analyzed using pole figures, created using the Material Analysis Using Diffraction (MAUD) software.

Two-layer metallic sheets have wide applications in aerospace, marine, automotive and domestic industries due to their superlative characteristics. In this paper, the Formability of two-layer sheet is investigated through analytical, experimental and numerical approaches. An analytical model is developed based on Marciniak-Kuczynski method associated Hill’s non-quadratic yield criterion. Forming limit diagrams are also obtained numerically based on finite element method using Bifurcation theory and ductile fracture criteria. Furthermore, experiments are carried out on Al3105-St14 two-layer sheet. Theoretical results from various methods are compared with results obtained from experiments to evaluate the competency of discussed analytical and numerical methods to predict the Formability of two-layer sheets. The results show that analytical and numerical approaches discussed in this paper have good capabilities to predict the Formability of two-layer sheets. However, the analytical method based on M-K model and numerical approach based on bifurcation theory are more suitable to determine the forming limit diagram of Al3105-St14 two-layer sheets.

In this paper, the mechanism of improvement of Formability in pulsating hydroforming of T-shape tubes is investigated by the finite element simulation and experiment. It is shown that local thinning was prevented by oscillating the internal pressure, because the protrusion is formed gradually by the prevention of sharp bulging. In the hydroforming, for the pulsating pressure, several steps occur in variations in wall thickness, and thus, the thickness of the tube increases, whereas, for the peak pressure, the thickness is reduced continuously. Moreover, the effects of the amplitude and the number of cycles of pressure per unit punch, the stroke on Formability and the corner filling are examined. It is shown that the small number of cycles of pressure and large amplitudes improve the Formability, whereas, a large number of cycles of pressure and small amplitudes increase the die corner filling and shape accuracy as well.

This paper reports the results of a study undertaken to investigate the effect of various manufacturing parameters, viz. finishing temperature of hot-rolling (830-910 oC), coiling temperature (540-630 oC) and the amount of cold-rolling reduction (52-75%) on the Formability of low-C sheet steel manufactured by Mobarakeh Steel Co. of Iran (MSCI) for autobody applications. The assessment was based on evaluating the effect of the sheet steel of a single manufacturing parameter at a time, on the work hardening exponent, rate sensitivity index, normal anisotropy and forming limit diagram (FLD). The results of this investigation indicate that an improvement in Formability could be gained by increasing, the finishing temperature of hot-rolling up to 870 oC. However, increasing this temperature beyond 870 oC gives rise to a marked deterioration in Formability. The optimum range of coiling temperature was found to be from 540 to 570 oC. Finally, with regard to the amount of cold reduction, the optimum reduction in thickness for improved Formability was established to be in the range of 60-70%.