An Investigation of the The dynamic Young Moduli of Twisted Fibres

This paper describes a modified laser system to measure the dynamic Young modulus and logarithmic decrement of damping for twisted fibers. A modified impulse mechanical spectrometer was designed and built by the authors. The effect of twisting on the values of the dynamic Young modulus and logarithmic decrement of damping was studied. The dynamic Young modulus and logarithmic decrement of damping were investigated for long PET fibers with a 200 mu m diameter. This experimental method does not require calibration because it contains standard length which is the wavelength of the laser beam.