The research activities presented in this paper were carried out within Sub-Project 6 of APROSYS (Advanced PROtection SYStems), an European Project to decrease the number of fatalities on European roads. SP6 deals with the development of a pre-crash system which improves structural behaviour in side crash. A pre-crash-system contains of a sensor unit, a data processing unit and at least one actuator. If there is a crash unavoidable ahead the actuator shall be deployed because of a sensor signal, remarkably before the impact happens. The benefit of a pre-crash system compared to currently implemented crash systems is its gain in time. More time and space is available for the deployment of any restraint system. On top, this additional time offers the opportunity that parts which fulfill a comfort function in normal driving situation can be activated to turn to a protection function in a crash situation. In this respect any adaptive device offers a great potential for being used in a pre-crash-system. Therefore, this paper presents different studies on actuator concepts of such a system, their performance and the integration of a favorite concept. The targeted vehicle for an actuator implementation within this study is a Chrysler/Dodge Neon (model year 1992 to 1999). For side crash structural behaviour assessment, crash test results were made available as well as a numerical reference FE-model (Radioss) of the Neon, validated for Euro NCAP side impact protocol, by Cidaut, Spain, via the partnership of APROSYS. The crash tests issued that the B-pillar was massively loaded and by this, for the actuator layout, two strategies were suggested: concepts to stiffen up locally the B-pillar (E.g. door locking to rocker and to B-pillar, continuous side impact beam from A to C pillars) and concepts which redirect crash loads away from the Bpillar to other car structures non impacted (E.g. transversal structures from struck side to the tunnel or the unstruck side). A generic FE model, previously created was used to investigate the concepts. As outcome of this study, a crash load redirection to the unstruck side was found to be by far, most powerful. The actuator of this concept takes the crash loads directly from the incoming object at the door. The deployed actuator system creates a rigid connection from the struck door to stiff car regions and by this structures other than B-pillar are immediately involved in crash. From the first contact phase, much more structure is involved in the energy absorbing process. This actuator comprises mainly a tube structure which is integrated in the seat. A bolt is pushed out and locked into the door, creating a tight connection from seat to door. The release of the bolt uses the principle of Shape Memory Alloys (SMA). The SMA wire being electrically heated in a precise temperature domain shortens and by this activating the mechanism for the bolt to be pushed out in a very small time span. This system changes the crash deformation modes completely, not only the B-pillar intrusion is dramatically reduced, but as well door intrusion is reduced significantly in regions being most critical for the occupant, therefore a considerable reduction of injuries is to be expected by using such a pre-crash system.
Novel SMA-actuator system for enhancing side impact safety
Neuartiges-Aktuatorsystem mit Formgedächtnislegierung für die erhöhte Seitenaufprall-Sicherheit
2008
6 Seiten, 11 Bilder, 1 Tabelle, 6 Quellen
Conference paper
English
Novel pre-crash-actuator-system based on SMA for enhancing side impact safety
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