Automated Torsion Pendulum: Control and Data Collection/Reduction Using a Desktop Computer.

摘要

A torsion pendulum interfaced with a desktop computer form an automated instrument for dynamic mechanical characterization of polymeric materials. The computer controls the initiation of the oscillation, collects the digitized data and calculates the shear modulus and loss modulus from the damped oscillations, utilizing one of four methods of analysis: (1) fitting the data points about the maxima and minima to a quadratic equation to obtain their times and amplitudes, from which the frequency and logarithmic decrement can be calculated; (2) fitting the data to a four-parameter equation of motion by a least squares technique; (3) fitting the data to a six-parameter solution to the equation of motion by a non-linear least squares technique; and (4) taking the Fourier transform of the data, which results in a maximum at the frequency of the oscillation whose amplitude is inversely proportional to the damping coefficient. (Author)