サーボ割算器を用いた定応力クリープ試験機

Abstract

The tensile load was automatically controlled so as to satisfy the loading condition for constant stress creep tests, W=W0l0⁄l, where W is the tensile force, l is the gauge length of specimen and suffix 0 stands for initial values. The elongation of specimen was measured by means of differential transformers. The output signal (equivalent to l) was fed into a servo-divider and a signal (equivalent to W) being proportional to reciprocal l was calculated. There were two holes at the bottom of a water vessel to increase or decrease the volume of water whose weight was applied to the specimen. Automatic control of the dead load was performed by free drainage and the supply of water controlled by a pneumatic valve in accordance with the calculated value of W. The tensile force acting on the specimen being directly measured by means of a load cell connected in series with the specimen and an automatic balancing indicator, could be controlled accurately against various disturbances. Maximum tensile force being 100 kg, a deviation of the force from the calculated value during constant stress creep tests could be kept within 1%. This creep tester can be applied for vacuum creep tests (>3×10−6 Torr) and also for tensile tests and stress relaxation tests at elevated temperatures (<900°C). A new precise temperature controller has been developed for stress relaxation tests.