Summary: Strain-controlled bulge test
B. Erdem Alacaa)
and K. Bugra Toga
College of Engineering, Koc University, Rumeli Feneri Yolu 34450 Sariyer, Istanbul, Turkey
Orhan Akar and Tayfun Akin
Electrical and Electronics Engineering Department, Middle East Technical University,
06531 Ankara, Turkey
(Received 26 March 2008; accepted 4 August 2008)
A closed-loop approach is adopted to implement strain rate control during the bulge
test. Due to the difficulty of measuring strains directly, the technique is based on the
conversion of displacement measurements to the corresponding strains using the
plane-strain formulation. The necessary temporal evolution of the midpoint
displacement of a rectangular diaphragm is derived under the condition of constant
strain rate and is imposed as a control criterion. The technique is demonstrated on
500-nm-thick Au diaphragms by applying strain rates ranging from 2 × 10-6
to
2 × 10-4
s­1
. By measuring the corresponding yield strength values, a strain rate
sensitivity of 0.11 is obtained, which is close to what was previously reported on

Source: Akin, Tayfun - Department of Electrical and Electronics Engineering, Middle East Technical University
Alaca, B. Erdem - Department of Mechanical Engineering, Koc University

Collections: Engineering