۱٫ Introduction

۲٫ Electro Magnetic Puls Technology

۳٫ Design, materials and manufacturing of the coupons

۴٫ Experimental investigation

۵٫ Summary and assessment of the quasistatic and fatigue testing results

Acknowledgements

References

During a still running European Project the feasibility of vehicle light weighting technologies for the manufacturing of light urban electric vehicles with new standards of mechanical performance will be demonstrated. One of the innovative technologies of the project, the Electromagnetic Pulse Technology (EMPT), which is a high speed crimping method, will be applied for joining of particular structural parts of the body, especially to join different lightweight materials such as Al- or Mg-tubes and Al- and Mg-cast or forged nodes. Current heat-intensive joining processes are faced with a number of drawbacks and “cold” classical adhesive techniques require cost-intensive preparation methods plus long curing times and show design uncertainties in terms of mechanical strength. Hence, joining of dissimilar materials is presently not widely used. The Electromagnetic Pulse Technology (EMPT) is an innovative approach for joining particular structural parts, where different lightweight materials can be joined without any significant heat input by a fast process. Therefore, this technology is determined as a high efficiency joining process from the quality and the energetic point of view, with virtually no loss of energy in form of heat. Presently, no design relevant characteristic values of such joints, neither endurable stress amplitudes (fatigue) nor stiffness behaviour of the connection during cyclic loading, are available. Hence, the reliability of such EMPT joints has to be validated with regard to fatigue and stiffness behaviour in order to guarantee a durable connection under typical service loading conditions. This paper will present first fatigue testing results for aluminium tube joints of EN AW-6082-T6 with a diameter of 40mm. Within this investigation the endurable strength and stiffness behaviour of EMPT joints will be determined in order to validate the performance of the Electromagnetic Pulse Technology for reliable applications under cyclic loading for e. g. urban electric vehicles.

Introduction

The project URBAN-EV aims to demonstrate the feasibility of light weighting technologies for the manufacturing of light urban electric vehicles with new standards of mechanical performance and occupant safety. The target is placed in a two seats car, with a targeted final weight of maximum 450 Kg (excluding rechargeable energy storage system).In order to achieve this goal, the URBAN-EV consortium will design, manufacture and demonstrate new lighter architectures with enhanced engineering reliability for the principal systems of the vehicle such as chassis and body in white. Most of the applied materials will be light alloys and low cost, high integrity polymeric composites, which will be combined using an advanced multi-material design approach. Current heat-intensive joining processes (arc welding, uncontrolled resistance spot welding) are faced with a number of disadvantages, such as need for using gases and filter wire, the generation of a heat affected zone, usually rich in brittle intermetallics as far as metals are concerned, and a relatively low productivity. On the other hand, “cold” classical adhesive techniques require cost-intensive preparation methods plus long curing times, and show uncertainties in terms of mechanical strength. Mechanical fastening, in turn, is inherently faced with the stress concentration around the joint and will be increased by joining dissimilar materials (especially when metals are concerned). In consequence heat-intensive methods will be reduced to the minimum extent possible within the URBAN-EV project.