Abstract: A method, apparatus, for subjecting a test object to vibrational energy testing is disclosed. The apparatus comprises a rotatable joint such as a hydrostatic ball joint for transmitting energy from a force generator to the test object, and a support structure, coupled to the test object and the rotatable joint, for flexibly restraining the test object from rotating about the center of rotation of the rotatable joint. In one embodiment of the invention, the support structure comprises a support member and at least one suspension device disposed between the support member and a ground datum. In another embodiment, the suspension device applies a suspension force to the support member in a direction substantially perpendicular to a vector from the center of rotation to the suspending force. In this embodiment the suspension devices are subjected primarily to compression and tension forces.