薄い高分子フィルムのための高速引張試験機の試作
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概要
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A high speed tensile tester was designed to study the tensile properties of thin polymer films using a flywheel. The tester consisted of a variable speed motor (1-HP) coupled to a flywheel, tooled from steel disc, through pulleys. It provided tensile speed over the range from 0.1 to 10 m/sec. The force arising while testing the sample was detected by means of a semiconductor strain gauge whose output signal was fed to vertical deflection plate of an oscilloscope. The sweep of the oscilloscope was triggered when the light beam to a phototube was traversed by striking-fork mounted on the rim of the flywheel just before stretching the sample. The amplifier of the oscilloscope ws flat from DC to 100kc. The resonance frequency of the strain gauge with a clamp for the sample was 1.1 kc and its sensitivity was 2.5mV/kg if the carrier voltage was 1 V. The response of the high speed tensile tester to the force arising in stretching the sample was examined by means of an analogue computer. The response relates to the true stress, strain, the strain rate, resonance frequency and the damping of the gauge and upper and lower cut-off frequencies of the amplifier recorder system. The motion of the gauge should be represented by the following equation : [numerical formula] where x is displacement, M is the effective mass of the moving part including the mass of clamp. F(t) is considered stress function which shows load-time relation of the sample. The difference of the observed load-time curve from the true under 1 m/sec of tensile speed is shown for various band-width of amplifier and resonance frequencies of the gauge. From the results, it is found that the observed load-time curve at 1 m/sec of tensile speed is in accord with the true curve if the upper cut-off frequency of an amplifier is 5kc, the lower one is DC and resonance frequency of the gauge is 2kc, and higher speeds these values increase proportionally except the lower cut-off frequency. Considering the above analysis, stress-strain curves of the commercial film of cellulose-triacetate are indicated at the rates of strain form 200 to 8000 %/sec. The results are compared with those of the tests carried out on the same materials with an Instron type tester at the rates of the strain of 0.17, 1.7 and 16.7 %/sec.
- 社団法人日本材料学会の論文
- 1965-04-15