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Accurate Simulation of Tailor-Welded-Blanks to Reduce Process Design Time for the Sheet Pressing Industry

Final Report Summary - SIM-TWB (Accurate Simulation of Tailor-Welded-Blanks to Reduce Process Design Time for the Sheet Pressing Industry)

The project SIM-TWB pursued advances in simulation technology, in order to take full advantage of concurrent engineering approaches to reduce time and cost, improve quality and safety and enable advances in tailor-welded-blank technology and usage.

The strategic objectives of the SIM-TWB project were (in order of importance):
- improving concurrent engineering practises within the tailor-welded-blank (TWB) manufacturing sector in order to reduce costs, improve quality and reduce time-to-market. The aim by the end of the project is to reduce the current average time to produce a working die by at least 30-40 %.
- providing accurate simulation for the prediction of tailor-blank manufacture therefore achieving a nearly 'right-first-time' design. This will be possible by the end of the project so that more than 80 % of problems are solved prior to the first prototype and should enable physical die trialling to be reduced to a maximum of two trials.
- improving welding technology (speed, methods and curved weld-seams) to enable the freedom of choice in the use of high-performance steels and aluminium for tailor-blanks within industrial production lines, without any reduction in production speed.
- reduction of vehicle weight while increasing safety and reducing fuel consumption. It is difficult to quantify the amount of vehicle weight that can saved but it is estimated that a further 10 %-20 % weight reduction may be achieved by using high-performance materials - this should be achievable without increasing the overall material cost that is currently about EUR 1250 of sheet steel per passenger vehicle. Fuel usage and emission will be reduced in the same proportion.

Based on current simulation practises, it is estimated that these advances in the modelling of tailor blanks due to the advances in the SIM-TWB project will:
- provide at the very least the same accuracy compared to current complex models requiring transition zones, changes in material characteristics, long CPU times, etc.;
- remove the need of modelling the weld seam as a transition zone with its material constitutive model or models and the inclusion of additional stiffener elements to model the bending and torsion stiffness along the weld. The number of parameters may be reduced by as much as 90 %;
- reduce engineer time in preparing the initial model by at least 70 %;
- reduce the CPU time required for a single simulation run by approximately 20 % reducing the calculation time for the weld seam;
- reduce the time required in obtaining the final solution by at least 60 %;
- in this manner an engineer can at least double the number 'what-if' simulations carried out and therefore has more possibilities of optimising the product and process (real example: the weight of a door panel was reduced by 34 % instead of 25 % when the number of trial designs was doubled).

The project work done over the period was divided into the following work-package tasks:
WP1. Software and experimental specifications: A complete specification for weld modelling including the mathematical / program specification of weld modelling and the experimental / simulation plan for weld seam characterisation. A compilation of the SME technical requirements in order to cover most of the needs related to the numerical simulation of the tailor-welded blanks usage in industry.
WP2. Experimental and numerical characterisation: The characterisation of welding processes and materials via experimentation, including characterisation of laser and diode laser welding processes for steels and FSW welding processes for high-performance materials.
WP3. Numerical development of models: The weld seam numerical behaviour model and the weld macroscopic constitutive model with initial verification were created and the initial software version for tailor-blank modelling was released, including training documentation on tailor-blank modelling.
WP4. Industrial technological enhancements: On the practical side the SME partners completed many studies looking at enhancements for the press tooling for tailor-blanks utilising steels and the applicability of high-performance materials for tailor-blanks.
WP5. Industrial implementation: Training was carried out so that the SMEs and RTDs learnt how to use the software that was created. The software was used for carrying out pilot studies of tailor-blank modelling.
WP6. Dissemination and exploitation: General dissemination and exploitation actions.
WP7. Project management: Project management and organisation of meetings.

The SIM-TWB project objective combines new industrial design tools and simulation development to provide the following direct benefits to the SMEs:
- effective design, development and implementation of new manufacturing techniques for TWBs: curved weld seams, FSW welding, stamping of aluminium tailor-blanks;
- improved understanding and characterisation of laser and friction stir welding techniques;
- improved die design to control twisting and movement of weld seam;
- reduced trial-and-error and manufactured prototypes implying reduced time-to-market;
- confident use of high-performance steels and aluminium in tailor-blanks;
- improved and knowledge-based product / process design methodology from TWB using CAD-CAE and a closer working relationship between clients and providers;
- reduced cost of overall cost of manufacture.

The main project result was the useable software modules which all the SMEs will exploit directly by installing and utilising in-house. However, they do not wish to involve themselves in any proprietary issues since software requires maintenance, continual development and support for which they do not have the required structures or personnel. It has therefore been agreed that Quantech assume ownership of the tailor-blank software modules, integrate them within Stampack, and protect them as necessary. Quantech will, on the other hand, provide special terms and usage conditions for the SMEs without whom these modules could not be developed, but who acknowledge the fact that the SME rights lie with the direct results of the SIM-TWB project. The consortium also agrees that the RTD Performers have special terms for the usage of the software modules and the Stampack software for academic and R&D purposes since it is natural that future collaborations will benefit all parties.

The development of the better simulation technology will help introduce technical expertise and status in the metal forming industry leading to a more knowledge-based industrial sector and enabling the sector to incorporate new advances in virtual production, supply chain and life-cycle management. The application of simulation contributes to the attractiveness of the work in the metal forming sector and requires recruiting skilled engineers to be trained in using this technology. Increased scope and opportunity in the job market is provided due to software advances since it is possible to utilise engineers that do not have formal university training or only a basic engineering degree.