Comparison of Analytical Model to Experimental Results and Numerical Simulations for Tailor Welded Blank Forming

Author(s):  
Matt Bravar ◽  
Brad Kinsey ◽  
Neil Krishnan

Tailor Welded Blanks offer several notable benefits including decreased part weight, reduced manufacturing costs, and improved dimensional consistency. However the reduced formability and other characteristics of the forming process associated with TWBs has limited the industrial utilization of this blank type. One concern with TWB forming is that weld line movement occurs which alters the final location of the various materials in the TWB combination. In this paper, an analytical model to predict the initial weld line placement necessary to satisfy the desired, final weld line location is presented. Good agreement between the model, experimental results, and numerical simulations with respect to weld line movement and initial placement was obtained for a symmetric, steel TWB case and a non-symmetric, Aluminum TWB case.

2006 ◽  
Vol 129 (1) ◽  
pp. 211-215 ◽  
Author(s):  
Matt Bravar ◽  
Neil Krishnan ◽  
Brad Kinsey

Tailor welded blanks (TWBs) offer several notable benefits including decreased part weight, reduced manufacturing costs, and improved dimensional consistency. However the reduced formability and other characteristics of the forming process associated with TWBs has hindered the industrial utilization of this blank type for all possible applications. One concern with TWB forming is that weld line movement occurs, which alters the final location of the various materials in the TWB combination. In this technical brief, an analytical model to predict the initial weld line placement necessary to satisfy the desired, final weld line location and strain at the weld line is used. Results from this model are compared to an experimental, symmetric steel TWB case and a 3D numerical simulation, nonsymmetric aluminum TWB case. This analytical model is an extension of one previously presented, but eliminates a plane strain assumption that is unrealistic for most sheet metal forming applications. Good agreement between the analytical model, experimental, and numerical simulation results with respect to initial weld line location was obtained for both cases. Results for the model with a plane strain assumption are also provided, demonstrating the importance of eliminating this assumption.


Author(s):  
Brad Kinsey ◽  
Matt Bravar ◽  
Jian Cao

Tailor Welded Blanks (TWBs) offer several notable benefits compared to traditional sheet metal parts including decreased part weight, reduced manufacturing costs, increased environmental friendliness, and improved dimensional consistency. In order to take advantage of these benefits, however, designers must overcome formability concerns related to stamping TWBs and be able to accurately predict unique characteristics related to the forming of this blank type. In this research, an analytical model using a 2D cross-sectional approach was devised and implemented to predict the weld line movement and forming height for a uniform binder force TWB application. The inputs into the analytical model are the desired strain at the weld line location, the geometry of the 2D cross-section, material properties, and the frictional condition. From this information, the model predicts the stress and strain at several key locations on the 2D cross-section as well as the movement of the material in the binder area and in the formed walls.


2003 ◽  
Vol 125 (2) ◽  
pp. 344-351 ◽  
Author(s):  
Brad L. Kinsey ◽  
Jian Cao

Tailor Welded Blanks (TWBs) offer several notable benefits including decreased part weight, reduced manufacturing costs, increased environmental friendliness, and improved dimensional consistency. In order to take advantage of these benefits, however, designers need to overcome the reduced formability of TWBs and be able to accurately predict unique characteristics related to TWB forming early in the design process. In this paper, an analytical model to predict the weld line movement and forming height for a uniform binder force, TWB forming application is presented. Comparison to numerical simulation results demonstrates the accuracy of this methodology. The analytical model provides designers a valuable tool to determine the location of steps on the die surface to accommodate the weld line movement and the potential forming height for a TWB forming with a uniform binder force. The methodology presented here has the potential to be extended to analyze a non-uniform binder force forming of TWBs.


2003 ◽  
Vol 125 (3) ◽  
pp. 461-467 ◽  
Author(s):  
Sijun He ◽  
Xin Wu ◽  
S. Jack Hu

Tailor-welded blanks (TWB) are widely used for stamped auto body panels because of their great benefits in weight and cost reduction. However, the weld line in a tailor-welded blank causes serious concerns in formability because of material discontinuity and additional inhomogeneous stress/strain distribution. This paper proposes a blank holding force (BHF) control strategy to control the weld line movement, distribute the deformation more uniformly and thereby improve TWB formability. The control methodology is developed based on a simplified 2-D sectional analytical model that estimates the stress/strain distribution and the BHFs required for each side of the flange with dissimilar materials. The model can be further extended to 3-D analysis by superimposing the 2-D sectional analysis results around the entire binder ring and thus determining the required BHF for the whole panel. Finite element simulations are performed to study the effects of forming parameters on the weld line movement. Experiments have been conducted to verify the analytical model and partial finite element simulations. Both analysis and experiments demonstrated that a lower BHF should be applied on the thicker blank side to allow more metal to flow-in for obtaining more uniform strain distribution. The proposed BHF control is proven to be a good approach to enhancing TWB formability.


Author(s):  
VVN Satya Suresh ◽  
Srinivasa Prakash Regalla ◽  
Amit Kumar Gupta

In this work, the formability aspects in terms of desired cup height during stamping operation of tailor welded blanks have been studied along with minimizing the movement of weld line. Circular sheets were prepared by joining austenitic stainless steel (ASS 304 Grade) and drawing quality mild steel (AISI 1018) materials with tungsten inert gas welding. To reduce the undesirable weld line movement during stamping process, a novel heat-assisted forming method involving localized and controlled heating of the stronger material side (ASS 304 steel) has been carried out. The experimental setup developed for this purpose enabled heating and maintained the selected zone at the desired temperature during the stamping process. The entire process has been simulated using finite element method and the results obtained were in close agreement with the experimental results. The effect of selective heating of tailor welded blank also resulted in the overall improvement in the quality of the product.


Author(s):  
A. Kumar ◽  
V. Gautam ◽  
D. R. Kumar

Tailor welded blank (TWB) has many advantages over a traditional blank for manufacturing automobile sheet metal components, such as significant flexibility in product design, higher structural stiffness, and crash behavior. However, lower formability and weld line movement are some of the problems associated with forming of TWBs. Hydroforming is a potential technique to enhance formability. In this work, the effect of thickness ratio on maximum dome height and weld line movement in hydraulic bulging of laser welded interstitial-free (IF) steel blanks of different thickness combinations has been predicted using finite element (FE) simulations. The results are also validated with hydraulic bulging experiments on TWBs. It has been found that with increase in thickness ratio, the maximum bulge height decreased and weld line displacement toward thicker side increased. These results have been used to relocate the weld line toward the thinner side in the initial blanks and achieve a more uniform bulge profile of the dome. The peak pressure to achieve maximum safe dome height and percentage thinning has also been found out. The results showed huge improvement in uniformity of bulge profile with little reduction in dome height.


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