High performance very low frequency forced pendulum

Abstract

A forced torsion pendulum has been constructed for the measurement of mechanical loss angle (tan δ ) and elastic shear modulus in three different modes: (a) as a function of temperature (80–1250 K), at imposed frequency, during heating or cooling at imposed heating or cooling rate (0.1–5 K/min); (b) as a function of frequency (10–10 −4 Hz) in isothermal conditions, and (c) as a function of amplitude (5×10 −6 to 5×10 −5 ) at imposed frequency and under isothermal conditions. The mechanical part of the pendulum has been designed in such a way that torsional plastic deformation of the specimen can be performed in situ, i.e., at low temperatures to generate fresh dislocations in metals, and at high temperatures to enhance grain boundary sliding, for instance. The whole installation is computer controlled and exhibits not only outstanding performances but also a very high capability of working in different conditions, being a useful tool for studying a large variety of mechanisms in different materials.