Symulation of Hydroforming on Tailor-Welded Tubular Blanks Using solid-shell Finite Elements

Combination of Hexahedral and Prismatic Solid-shell Finite Elements

Mechanical behaviour of dissimilar friction stir welded tailor welded blanks in Al–Mg alloys for Marine applications

Formability of tailor welded blanks (TWBs) and control of blank deformation during stamping is always a challenge for manufacturing designers due to different properties or thicknesses of the blanks. The plastic deformation capacity of TWBs is reduced even when the material and thickness are the same. Same material same gauge TWBs (SMSG- TWBs) are now widely applied to mass production of automobile components for raising the utilization ratio of materials and expanding the dimension of steel coil. The aim of this work is to investigate the formability of SMSG-TWBs by both numerical and experimental approaches. Local constitutive properties of laser welded beads are determined by tensile tests with the aid of digital image correlation (DIC). Based on these mechanical properties, the formability of TWBs and monolithic blank are evaluated by performing Erichsen cupping tests numerically and experimentally. The influence of weld on strain distribution is discussed as well. Comparisons with the experimental results showed general agreement.

<div class="htmlview paragraph">One of the most popular weight reduction strategies in auto bodies is usage of tailor welded blanks (TWB). TWBs with high-strength low-alloy steels and advanced high-strength steels (AHSS) offer possibility of significant weight reduction. In the present work laser welding studies were carried out to fabricate TWB's involving 1.6 mm thickness AHSS DP 590 (dual phase steel) and 0.8 mm thickness conventional IF (interstitial free) steel in different combinations and characterized for their metallurgical and formability characteristics. Fusion zone microhardness was varying with change in material combination. While DP590-DP590 and IF-IF have shown fusion hardness of 300-350HV and 150-180HV, respectively, the dissimilar DP590-IF showed a fusion zone hardness of 250-330HV.Beam offsetting towards the thinner side has reduced the peak hardness. Microstructural analysis revealed mixture of martensite and refined ferrite in the fusion zone of dissimilar welds. The erichsen cup height for TWBs (11 mm) was between cup heights of the welded coupons of the two base metals DP590 (9.5-10 mm) and IF (13.5-14 mm), respectively. Limiting Dome height tests also revealed a similar observation that the limit strains of the TWBs are between the limit strains of the two base materials.</div>

<p>The drive towards weight reduction in the automotive industry has led to the use of tailor welded blanks (TWBs). This work is aimed at evaluating the forming and fatigue behavior of the TWBs with different thickness combinations and compositions. Forming tests were carried out to determine the forming limit diagrams (FLDs) of the TWBs, and compared with those of the individual steel sheets. The results showed that the FLDs of the TWBs lie in-between those of the individually formed steel sheets that comprise the TWBs. A semi-empirical relation based on the mean values of the strain-hardening exponents (n-values) and of the thickness of the base metals was developed to calculate the FLDo of the TWBs. The calculated FLDo values were found to be in good agreement with the experimentally determined values. The fatigue tests showed that TWBs made from zinc coated/galvanized steels exhibited a lower fatigue limit, as compared with the TWB combinations from comparable uncoated steel. This was attributed to the intergranular cracking in the galvanized TWBs, caused by the presence of zinc penetrating beneath the sheet surface.</p>

This paper presents an investigation on forming limits of tailor-welded blanks (TWBs) made of 5754-O aluminum sheets using both experimental and numerical approaches. TWBs may be composed of two or more welded flat metal sheets of different thicknesses, shapes, or mechanical properties. Due to the existence of weldment and the individual configurations of base blanks, TWBs should be considered as heterogeneous in its structure. The mechanical properties of those base metals and weld metal required for the simulation were measured individually. With the aid of the acquired data, finite element simulations for analyzing the forming process of TWBs were carried out using a general purpose finite element package, LS-DYNA. A localized necking criterion based on the vertex theory was employed to predict forming limit strains and failure locations of the aluminum TWBs. The theoretical predictions were satisfactorily validated with those obtained from the experiments.

The purpose of this study is to improve the mechanical properties and formability of friction stir welded tailor-welded blanks (TWBs) of Al6061 alloy with a new forming method called hot forming quenching (HFQ) in which solid-solution heat-treated aluminum sheets are formed at elevated temperature. Forming and quenching during HFQ are simultaneously performed with the forming die for the solid-solution heat-treated sheet. In this study, specimens of aluminum TWBs were prepared by friction stir welding (FSW) with a butt joint. The effectiveness of FSW joining was evaluated by observation of the macrostructure for different sheet thicknesses. In order to evaluate the formability of TWBs by HFQ, a hemisphere dome stretching test of the limit dome height achieved without specimen failure was performed with various tool temperatures. A Vickers test was also performed to measure weldment hardness as a function of position. The formability and mechanical properties of products formed by HFQ are compared with those formed by conventional forming methods, demonstrating the suitability of HFQ for sheet metal forming of friction stir welded TWBs.

An eave-like model for the welding of 304 stainless-steel tailor-welded blanks with different thicknesses

Using tailor-welded blanks (TWB) in automotive industry is on the rise. This is done due to advantages such as reduction in weight leading to more effective operational cost and lower energy consumption of vehicles. The main objective of this investigation was to study the effect of location change of weld zone and differences in thickness combination of TWB sheets on their tensile characteristics and forming capabilities. Quality evaluations of weld zone metallographic and tensile as well as ball punch tests have been conducted. Tension characteristics of welded samples have been determined by conducting a uni-axial tensile test perpendicular on the weld line in those samples. Forming capability of TWB samples were also studied by using sphere head chisel test. By moving weld line toward thick sheets direction and increasing thin sheets share of the weld in TWB, an increase in relative elongation in tensile test and in chisel test increase in cups height was observed. This indicates that forming capability of TWB samples by moving weld line toward thick sheet increases and weld zone does not have much effect on forming capability of TWB. By using the derived recommended relation induced from this study, it is conceivable to obtain the amount of increase in relative length of TWB from its base sheets. Results of this relation are confirmed with obtained results from tensile test. Also by reduction in thickness difference of TWB sheets, their formability increases.

Fatigue behavior of tailor (laser)-welded blanks for automotive applications

Formability of similar and dissimilar friction stir welded AA 5182-H111 and AA 6016-T4 tailored blanks

An investigation on the laser welding process parameter effects on the failure mode of tailor welded blanks during the formability testing

Investigation into the effects of weld zone and geometric discontinuity on the formability reduction of tailor welded blanks

ABSTRACTAn attempt was made for the first time to fabricate tailor-welded blanks (TWBs) through the feasibility of selective alloying in the solid state of vertical compensation friction stir welding (VCFSW) technique. The results revealed that the production of TWBs by VCFSW technique had higher homogeneity without any defects when compared to the production of TWBs by conventional FSW process at constant tool rotational speed 2000 rpm, traverse speed 20 mm min−1 and an inclination angle 2.5°. The maximum mechanical properties of the fabricated TWBs were obtained when the width of compensation strip 1.5 mm was used. The fracture surface of TWB at the width of compensation strip 1.5 mm showed ductile fracture mode.

<div class="htmlview paragraph">The Automotive Industry is a leading force seeking innovative solutions towards the weight reduction, safety regulations compliances and costs reduction. These directs the Automotive players in the development of several fields, from materials, manufacturing process, product development and others, to work as close as possible to reach improved and cheaper products in less time. In the past decade, strong efforts were made in the material science, namely in new steel products, such as: Multi-phase Steels; Boron Steels; Martensitic Steels; Twip Steels.</div> <div class="htmlview paragraph">In parallel to the material science progresses, the manufacturing processes were evolved as well. In this field, to comply the nowadays complexity and the high resistance of the demanding new Automotive structural parts, several manufacturing processes were improved and implement: Hydroforming; Rollforming; Hotforming; Tailor Welded Blanks; Joining technologies. To answer the new challenges associated to new automotive products, new regulations standards (safety and emissions targets), weight and cost reduction and short development periods, the numerical simulation tools are essential to fulfill all these issues.</div> <div class="htmlview paragraph">In this work, is presented an updated review, integrating new emerging materials and manufacturing processes. Furthermore, numerical simulation tools are applied in order to study the feasibility of an automotive sheet metal part that congregates new materials and recent implement manufacturing processes.</div>