Measuring and testing – Specimen stress or strain – or testing by stress or strain... – By loading of specimen
Patent
1996-12-04
1999-09-28
Noori, Max H.
Measuring and testing
Specimen stress or strain, or testing by stress or strain...
By loading of specimen
73789, G01N 1908
Patent
active
059592150
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a heat build-up/fatigue measuring method for a viscoelastic body and a hydraulic servo flexometer, which measure characteristics associated with heat build-up and fatigue by repeatedly applying a load to a viscoelastic body, e.g., rubber.
BACKGROUND ART
Conventionally, as a test method of evaluating fatigue characteristics associated with heat build-up in a test piece, e.g., vulcanized rubber, by applying dynamic repeated loads to the test piece, ASTM No. D-623-67 Method A is generally used. As a test machine for this purpose, a Goodrich Flexometer which complies with this standard has widely been used.
FIG. 15 shows the schematic arrangement of the conventional Goodrich flexometer used in the above test, the operation of which will be described hereinbelow. Referring to FIG. 15, a rotary motion of a driving shaft 203 driven by a driving motor 201 through a V-shaped pulley 202 is converted into a vertical motion by an eccentric 204 provided to the driving shaft 203. A test piece 210 formed into the shape of a circular cylinder is sandwiched between an upper anvil 211 and a lower anvil 212. A contact 214 of a thermocouple thermally insulated by an ebonite plate 213 is located at the central portion of the lower anvil 212, as shown in FIG. 16. Lead wires 215 extending from this contact 214 are connected to a temperature measurement device 216 to record the temperature of the test piece 210.
Static and dynamic loads are applied to the test piece 210. The compression load of the static load is applied by a balance. Balance weights 222 and 223 are respectively suspended from the two ends of a lever arm 220 of the balance. A load weight 224 having an adjustable weight is placed on the rear balance weight 223. When the load weight 224 is placed, the lever arm 220 tilts to push up the lower anvil 212 which is fixed to the upper surface of the lever arm 220 through an anvil adjustment screw 218 such that its height can be adjusted in the vertical direction. Hence, the compression load is applied to the test piece 210.
A differential transformer 225 is coupled to the rear portion of the lever arm 220. When the lever arm 220 tilts, the amount of its displacement, i.e., the change amount of compression of the test piece 210 is detected by the differential transformer 225. This detection signal is amplified by a motor control circuit (not shown) and converted into a rotation angle of a reversible motor 227. This rotation angle is decelerated by a gear head 228 and converted into a rotation of a rotating shaft, extending in the lever arm 220 in the longitudinal direction, by a worm gear incorporated in the lever arm 220 through an electromagnetic clutch 229. This rotating shaft rotates a helical gear. When the helical gear rotates, the anvil adjustment screw 218 rotates to move the lower anvil 212 in the vertical direction. As a result, the lever arm 220 is always controlled to be horizontal.
After the static load is applied to the test piece 210 in this manner, the eccentric 204 is rotated by the driving motor 201 to move a connecting rod 240 in the vertical direction, thereby moving in the vertical direction a connecting rod plate 242 coupled to the connecting rod 240 through a connecting rod pin 241. A cross bar holding upper anvil 244 is coupled to the connecting rod plate 242 through driving rods 243. When the upper anvil 211 provided in the lower portion vertically moves upon rotation of the driving motor 201, a compression strain (dynamic load) is repeatedly applied to the test piece 210. The amount of displacement of the upper anvil 211, i.e., the amount of deformation of the test piece 210 can be read by a deformation indicator 246 through an indicator rod 245 extending upward from the cross bar 244.
FIG. 17 shows the principle of the Goodrich flexometer described above. As is apparent from FIG. 15, the lever arm 220 can swing at its center and is supported by a knife edge fulcrum 221. The balance weights 222 and 223 each weighing 24 kg are respectively suspe
REFERENCES:
patent: 3597967 (1971-08-01), Drexler
patent: 4165634 (1979-08-01), Prevorsek et al.
patent: 4574642 (1986-03-01), Fleischman
patent: 5092179 (1992-03-01), Freguson
patent: 5275063 (1994-01-01), Steiger et al.
Ono Shigeki
Satoh Chikahiro
Yamada Akira
Bridgestone Corporation
Noori Max H.
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