| 摘要 |
1,130,585. Measuring force electrically. NEDERLANDSE ORGANISATIE VOOR TOEGEPAST NATUURWETENSCHAPPELIJK ONDERZOEK TEN BEHOEVE VAN NIJVERHEID, HANDEL EN VERKEER. Dec.7, 1965 [Dec.10, 1964], No. 51849/65. Heading G1N. A dynamometer element consists of a rectangular member having two longer sides 1, Fig. 1, and two shorter, substantially rigid sides 2, the force to be measured being applied to the middle of the longer sides 5, 6, and perpendicular to them, and strain gauges 7, 8, 9, or 10, being arranged symmetrically on either side of the axis of the force, on at least one of the longer sides. At two cross-sections (II-II) on each of the longer sides 1, the bending moment due to applied force is substantially zero, and pairs of strain gauges 7, 8, or 9, 10, are arranged symmetrically on either side of these cross-sections. By connecting the two gauges of each pair in opposite arms of a Wheatstone bridge, the non linearity in measuring signal which results from shifting of the zero bending moment section with varying applied force, is reduced. The effects of thermal changes in resistance of the strain gauges are eliminated by arranging that each strain gauge, 7 or 8, on the outer face of a side 1 is situated opposite a strain gauge, 9 or 10, on the inner face of the side, opposite pairs of gauges being arranged in adjacent arms of the Wheatstone bridge. To eliminate the effects of differential expansion of the two longer sides 1 due to a temperature gradient along the axis of the applied force, the strain gauges may be arranged on portion of only one of the longer sides, the respective lines joining the centres of gravity of adjacent cross-sections of each of these portions being perpendicular to the applied force. Alternatively, the gauges may be arranged on both the longer sides, on portions thereof which are constructed symmetrically about the line joining the mid points of the two shorter sides. |
