The invention is a mechanical device to be connected in series or in parallel to a structure that has to be protected from dynamic loads in order to vary the mechanical features of the system and control the general dynamic behavior. The main innovative features are high performance, compactness, muti-directionality and versatility of response.  This device is in fact a new multi-purpose rheological element that can be used in various applications including: (i) vibration isolation, (ii) vibration absorption, (iii) shock absorption, (iv) energy dissipation, (v) other applications based on rheological force-displacement behavior (energy harvesting, sensors and actuators).  

The device can be used in different scales to provide high isolation perfomances for buildings, precision instruments (laboratory and medical devices), nuclear reactors, culturale heritages, statues, servers and electronical equipments (strategic infrastructures). the device, if loaded in any direction in the horizontal plane, will exert, for a certain adjustable range of displacements, a force in the same direction of displacement (i.e. negative stiffness). In the presence of a relative displacement between the two ends of the device in the horizontal direction, the connecting rod rotates rigidly around the lower hinge, sweeping, by virtue of a shorter length than the alleged ropes, a greater angle than the latter.  

The advantages  of introducing a negative stiffness  in the total restoring force of the system are the possibility of obtaining a strong reduction of stiffness and therefore of accelerations and forces entering into the system, together with the achievement of a drastic amplification of the equivalent damping.