A. Ahmed-Alia, R. Baleh1,2, D. Razafindramary1,3 and A. Abdul-Latifa1,3 

1) Laboratoire d'Ingénierie des Systèmes Mécaniques et des Matériaux (LISMMA)

Supméca, 3, rue Fernand Hainaut - 93407 St Ouen Cedex, France

2) La Salle Passy-Buzenval, 50 avenue Otis Mygatt 92500 Rueil-Malmaison, France

3) Université Paris 8, IUT de Tremblay, 93290 Tremblay-en-France, France

rbaleh@passy-buzenval.com

Abstract: Thin tubes made from steel composite are experimentally investigated showing their energy absorption capacity during dynamic plastic buckling. In fact, steel-steel composite cylindrical tubes are characterized by a specific outer surface heat treatment. Only 15% of tubes outer surface are heat treated for a certain depth along tube thickness with different geometrical shapes. The patented idea· aims to enhance the impact resistance of tubular structures not only through the treated area but especially through its geometry.

A key point emerging from this study is that the structure impact response (i.e., the plastic flow mechanism and the absorbed energy) is influenced by the loading rate coupled with the heat treated configuration. To study the geometry effect of carburizing treated zone, seven different distinct shapes are extensively tested: three different ring-shape configurations (2, 4 and 6 rings), a configuration with three uniformly distributed vertical strips parallel to the axis of the tube and finally three treated helically cases with three different tilt angles of 30°, 45° and 60°. All the experimental tests are carried out using a dynamic drop mass bench of a maximum impact velocity of 10 m/s.

The obtained results show the enhancement in the energy absorption, notably in the case of 4-ring (and then helically case with a tilt angle of 60°) is higher than 75% in comparison with the non-treated case.

Keywords: plastic buckling; surface heat-treatment, dynamic loading; energy absorption