Thermoelastic property of the torsion fiber in the gravitational experiments

The thermoelastic and the nonlinear properties of a torsion fiber were stud ied. A symmetric disk torsion pendulum was designed to measure the temperat ure coefficient of the torsion spring constant of a tungsten fiber at room temperature, and the result shows that the ambient temperature fluctuation with +/- 1 degrees C would introduce a considerable uncertainty about -/+ 1 65 ppm in the torsion spring constant of the fiber. It is suggested that th e thermoelasticity of the torsion fiber should be measured in a precision t orsion pendulum experiment. (C) 2000 American Institute of Physics. [S0034- 6748(00)03203-2].