Evaluation of dynamic fracture resistance of laser and resistance spot welds for automotive applications
The behaviour of welded structures during a car crash is of great importance to automotive designers. This research used several kinds of dynamic tests and, in particular, a newly developed test called the impact tensile test (ITT), which was associated to a specific methodology for evaluating the tenacity of thin welds/mechanical assemblies in high strength steels (HSS) submitted to dynamic loads, such as those experienced in real crash tests. Crash results were revealed to be strongly dependent on the solicitations' modes and transferability, and the knowledge gained from ITT or dynamic tensile tests (DTTs) on single weld or assembly to real components is not immediate. Both ITT (the easiest test to perform) and DTT are well adapted to testing the quality of joints and permitted the optimisation of the welding or joining parameters, which is necessary when using high strength steels for crash resistance. For instance, post-heating during spot welding of Trip steels revealed interesting results with ITT to obtain plug failures and allowing one to concentrate only on the crash behaviour of base metal during crash tests on joined structures. Moreover, ITT could be implemented on a car production line as a simple qualification test, and could even be used as a development tool for the first numerical design, provided instrumented light-weight grips and coupons are used. The methodological advances reached should enrich the normalisation for evaluating crash resistance and the tenacity of thin welds. Finally, this important experimental work represents an exhaustive data-base of dynamic results on HSS materials which appear processable with conventional joining techniques.
Bibliographic Reference: EUR 22006 EN (2006), 145 pp. Euro: 25
Availability: Katalogue Number: KI-NA-22006-EN-S The paper version can be ordered online and the PDF version downloaded at: http://bookshop.europa.eu
ISBN: ISBN: 92-79-01100-6
Record Number: 200618672 / Last updated on: 2006-07-20
Original language: en
Available languages: en