LOW-TEMPERATURE CHARACTERIZATION OF CARBON-EPOXY COMPOSITES - AN APPLICATION OF RESONANT ULTRASOUND SPECTROSCOPY

Resonant ultrasound spectroscopy is the study of spectra obtained by f orced mechanical resonance of samples by swept frequency excitation. A novel apparatus is used to measure the amplitude/frequency resonance spectrum of a right rectangular parallelepiped specimen of AS4/3501-6 carbon epoxy composite material ([0, 60, 120]192 lay-up) at 1 degrees C intervals between - 177 degrees C and 25 degrees C. It is important to know the mechanical properties of this material at low temperatures for underwater, polar and space applications. The spectra indicate in creasing stiffness with decreasing temperature and phase transitions. The damping decreases slightly with decreasing temperature. Analysis o f the resonance spectrum, calculation of theoretical resonance spectru m, and computation of elastic stiffness tensor will be discussed.