An instrumented drop-bar impact testing apparatus for investigating the impact fracture behaviors of structural steels

• To develop an instrumented drop-bar impact testing apparatus.
• Load–displacement curves with lesser oscillations using a long bar striker.
• To determine reliable characteristic load parameters and absorbed energy.
• Reliable DAQ and processing scheme for impact fracture behavior analysis of steels.

In this study, an instrumented drop-bar impact testing apparatus which provides a load–displacement curve was introduced and used to investigate the impact fracture behaviors of structural steels. The instrumented impact apparatus was constructed with a long bar striker to reduce the oscillations appearing in the load-time record when a conventional pendulum-type instrumented Charpy impact tester was used. In addition, a new data acquisition and processing scheme based on LabVIEW S/W was integrated which makes the derivation of the load–displacement curves more convenient with less oscillation. Impact tests using standard Charpy V-notched specimens made of S45C and SM490B steels were performed to investigate the validity of the instrumented impact apparatus. Load–displacement curves with lesser oscillation were obtained, therefore important characteristic load parameters and absorbed energies in various phases of fracture could be determined. Their reliable determination was also discussed and compared with the corresponding fractographic observations.