Measurement of strain distribution on sheet specimen in tension test validating transition of strain distribution predicted by FEM

Abstract

In the present research work the authors tried to measure the non-uniformity of strain on the specimen throughout tension test to validate the results of FEA. Flat specimen of JIS5 was used to investigate the transition process of strain distribution. The material was pure iron. A cast ingot was elongated by hot forging to make a round bar which is 4 times as long as the ingot. The bar was subjected to thermal treatment to homogenize the grain size before flat specimens were sectioned from the bar. Strain gauges were placed on the specimen to monitor the transition of largest strain. An extensometer was also placed to measure the average strain between the two gauge points. Result of FEA analysis predicted that the largest value of strain is observable at the shoulder portion at the initial stage of yielding. The po ition of largest strain moved to an intermediate portion when the average strain increased and finally moved to the centre portion. The result validated the predicted result by FEA.