Device for displacing two bodies relative to each other

A device for displacing first and second bodies relative to each other, wherein the device comprises:

• first and second body;
• first means for associating the first piece with the first body;
• second means for associating the second piece with the second body;
• means for applying a force between said two pieces;
• a projecting portion secured to one of the two pieces;
• a cavity formed in the other piece, said cavity being complementary in shape to at least a part of said projecting portion;
• said first and second pieces being mounted for displacement relative to each other in such a manner that said projecting portion engages in said cavity;
• the piece in which said cavity is made being of a first material suitable for passing from an undeformable hard first state to a deformable soft second state, and vice versa, the undeformable hard state being a state in which said projecting portion cannot deform said first material under drive from said force, and the deformable soft state being a state in which said projecting portion, under drive from said force, can penetrate into said first material in such a manner that said first material can creep around said projecting portion, while the piece carrying said projection portion is made of a second material that is substantially undeformable;
• and
• means for controlling the passage of at least the portion of the first material that surrounds the cavity from the first state to the second state, and vice versa.