A new technique for measuring axial damping and its application to metal matrix composites.

摘要

A majority of the current experimental techniques for measuring damping employ either flexural or torsional vibrations. In either case the strain field is non-homogeneous. If the material damping is linear, that is strain independent, then the measured quantity is a true representation of the intrinsic material damping. If, on the other hand, the material damping is non-linear, that is strain dependent, then, in addition to the intrinsic material damping, the measured quantity is also a reflection of the non-homogeneity of the strain field.This dissertation presents a new technique for measuring the intrinsic material damping by employing a homogeneous strain field. Specimens were subjected to a time-harmonic uniform uniaxial tension using an MTS apparatus at frequencies between 0.5 Hz and 10 Hz. Using the elementary theory of Fourier transforms, the phase difference between the stress and the strain was resolved in the frequency domain (rather than in the time domain) to an accuracy of 9.587 The application of both techniques was illustrated by measuring the damping of a (