3. Shock absorbers

3.1 Definitions

Under the effect of an impact, two modes of plastic deformation can be observed:

• shear flow deformation without decohesion ;

• deformation with the formation of cracks and fractures.

All the energy transmitted during impact is divided between the two modes [8] .

• Ductile materials deform mainly by shear yielding. In this case, there is intermolecular sliding without density variation. Flow is limited to specific zones called shear bands.

  In brittle materials, stress leads to the appearance of voids containing pull-out...