Element (1) with variable stiffness controlled by negative pressure, the element comprising: - a gas-tight envelope (10)； - a plurality of flexible layers (30, 30a, 30b, 30c, 30d, 30e) in the envelope, each layer (30, 30a, 30b, 30c, 30d, 30e) having a first surface (31, 41) and a second surface (32, 42)； and, - a valve (20) adapted to evacuate the interior of the envelope (10)； characterised in that: - the first and second surfaces (31, 41, 32, 42) of two adjacent layers have a friction coefficient between each other which is higher than 0.5； - the first and second surfaces (31, 41, 32, 42) of two adjacent layers have adhesion properties, such that a normal force per unit area of below 0.07 N/mm 2 is required to separate them and/or the energy per unit area required to separate them in normal direction is below 6.7 J/m 2 .
