Search for stress dependence in the internal friction of fused silica

The quality factor (Q) of the vertical bounce mode of a fused silica fiber pendulum is measured at high and low stresses. The internal friction of fused silica fibers is found to be independent of stress from 12.8 to 213 MPa at a level of 1.6x10-8. Comparison with Q's of fiber bending modes is consistent with losses concentrated in the surface of the fiber