VARIABLE RIGIDITY ACTIVE MEMBER

PURPOSE:To obtain axial rigidity at desired positions by constituting the above captioned member suitable for the vibration control of space structures with an outer cylinder, an inner cylinder slidably engaged therewith and a piezoelectric element displaced in the radial direction by the conductance of electricity. CONSTITUTION:A case 2 is equipped with an outer cylinder 3 threadably engaged in its axial direction, and an inner cylinder 4, one end of which is slidably engaged in its axial direction inside the outer cylinder 3 while the other end is supported by the case 2. An adjusting mechanism 16 is composed of a tapered surface 11 formed on the outer periphery of the outer cylinder 3 and a plural number of slits 12 which give elasticity, and its inside diameter is narrowed down by the threadable engagement of the outer cylinder 3 in accordance with the tapered surface 10 of the case 2 to adjust its spacing with the inner cylinder 4. The inner cylinder 4 is equipped with sliding parts 21 divided into an upper and a lower portions, and a piezoelectric element 22 which connects the upper and lower sliding parts 21, and displaces in the radial direction on the conductance of electricity, so that the outer periphery of the inner cylinder 4 can be pressed against the inner periphery of the outer cylinder 3 through the displacement in the radial direction with the conductance of electricity to the piezoelectric element 22.