Compressive properties of magnesium alloy AZ91D at high strain rate

• Main Author: Ren, Jia
• Other Authors: Shu Dong Wei
• Format: Final Year Project
• Language: English
• Published: 2010
• Subjects: DRNTU::Engineering::Materials::Material testing and characterization
• Online Access: http://hdl.handle.net/10356/42580
• Institution: Nanyang Technological University

The Split Hopkinson Pressure Bar test is the most commonly used method for determining material properties under extreme loading conditions. The bar also provides relatively good accuracy when the equipments are calibrated correctly. The analysis of the mechanical properties of the specimens from the voltage generated by the oscilloscope is very crucial in this project. The oscilloscope datas’ are used to determine mechanical properties such as the maximum stress, maximum strain, strain rate and the stress-strain relationship. This report examines a Split Hopkinson Pressure Bar method using steel allay pressure bars and AZ91D specimens. Ideally, the specimen should be in dynamic stress equilibrium and should deform at a nearly constant strain rate. However, it is not possible to measure the elastic and early yield behaviours as stress equilibrium in the specimen is not achieved in the early stages. Pulse shaping technique was used to rectify this problem; ensuring stress equilibrium and homogenous deformation in the specimen by increasing the rise time of the incident pulse. Copper pulse shapers with different thicknesses were used to investigate the stress equilibrium and homogenous deformation of magnesium specimens. The dynamic deformation behaviors of magnesium material under compressive high strain rate are evaluated using the modified SHPB technique. This report documents some new improved and detailed procedures and recommendations in operating the setup as to minimize problems faced by future researchers.