| 摘要 |
<p>1,184,045. Measuring internal friction electrically. KONINKLIJKE ZWAVELZURFABRIEKEN VOORHEEN KETJEN N.V. March 15, 1967 [March 16, 1966], No. 12120/67. Heading G1N. The internal friction of a material (1, Fig. 1, not shown) is measured in terms of the energy required to maintain constant amplitude oscillations of a torsional oscillator which includes the material (1), and, for example a shaft (5) on a flexible support (15) and an armature having arms (6, 7, 8, 9) and weights (14) thereon; the said energy being proportional to the instantaneous velocity of oscillation and being supplied to coils (10, 12) from an amplifier (23, Fig. 2, not shown) which has its input connected to pick-up coils (11, 13). The pick-up coils 11, 13 measure acceleration or velocity, and the amplifier (23) has its gain automatically adjusted (at 24) by the difference between measured amplitude of oscillation (29) as obtained by integrating the velocity signal or double integrating the acceleration signal, and a reference amplitude (30). The adjustment of the gain control knob (24) is transmitted to an angle measuring device (32) driving a recorder (33), this giving a measure of the energy input to oscillating system and hence of the internal friction of the material. The measuring coils (11, 13) and driving coils (10, 12) all move in respective airgaps in yokes (19, 20, 25, 26), each of which has a central limb carrying a D.C. exciting coil (21, 22, 27, 28). A counterbalance weight (18) is adjustable on a lever arm (16) supporting the oscillating assembly.</p> |
