Device for providing a rigid mechanical link with frequency cut-off

A device for providing a rigid mechanical link with frequency cut-off between at least two structures, the device comprising a tie-rod of high stiffness having ends secured to the structures for transmitting static forces between the structures, the device further comprising a cylinder-piston assembly in parallel with the tie-rod, said cylinder-piston assembly comprising a piston secured to one of said structures and a cylinder secured to the other of said structures, and means for generating inertia instantaneously opposing the displacement of the piston in the cylinder in response to a substantially impulsive acceleration, said means comprising a duct having an internal cross-section and a length, the duct interconnecting two chambers formed in the cylinder on either side of the piston, and a liquid which completely fills the chambers and the duct, said liquid having such a low viscosity that frictional losses due to movement thereof are negligible so that the transmission to one structure of any substantially impulsive acceleration applied to the other structure, which causes displacement of the piston in the cylinder in one direction, is opposed by the inertia of the liquid displaced in the opposite direction in the duct, said inertia, when calculated at a location adjacent the piston, being substantially equal to the product of the mass of the liquid contained in the duct and of the square of the ratio of the area of a working surface of the piston over the area of the internal cross-section of the duct, the working surface of the piston being that which displaces the liquid in the cylinder, the area of this working surface being large relatively to that of the internal cross-section of the duct.