Result comparison of different methods for measuring plastic strain ratio of metal sheet

ISO 10113:2020 provides manual, semi-automatic and automatic methods for measuring the plastic strain ratio r value. The effects of three measurement methods, different measurement equipment and sample types on the measuring results were discussed. The results show that there was no significant difference in the r value measured by manual, semi-automatic and automatic methods, and the automatic method had the highest measurement accuracy. The r value measured by laser non-contact extensometer was close to that measured by mechanical contact extensometer, but the former had higher accuracy. When using JIS5 sample for r value measurement, 50 mm gauge should be avoided, and 20-30 mm gauge was recommended. Suggestions for revision of GB/T 5027-2016 were also made.