Evaluation of dynamic fracture toughness parameters by instrumented Charpy impact test

✍ Scribed by Kobayashi Toshiro; Yamamoto Isamu; Niinomi Mitsuo

• Publisher: Elsevier Science
• Year: 1986
• Tongue: English
• Weight: 769 KB
• Volume: 24
• Category: Article
• ISSN: 0013-7944
• DOI: 10.1016/0013-7944(86)90249-3

✦ Synopsis

This paper presents methods to determine two fracture mechanics parameters using loaddeflection curves obtained from instrumented Charpy impact test. Two fracture mechanics parameters are dynamic fracture toughness (Jd) and material tearing modulus (T,,,,,). Jd is fracture resistance at crack initiation and it is necessary to detect the crack initiation point on the loaddeflection curve for measurement of this value. On the other hand, T,,,s, is a parameter to characterize a stable crack growth and it is necessary to estimate an amount of crack extension.

In this study, it is attempted to detect the crack initiation point by calculating the compliance changing rate from a loaddeflection curve for the measurement of Jd. Next, J-Au curve is estimated by using a key curve method and T,,,at is determined from the slope of it. In addition, T,,, is evaluated by combining Kaiser's rebound compliance with Paris-Hutchinson's r,,, equation. The above results are compared with the ones of the stop block test (which is a multiple specimen technique), and are discussed with respect to their validity; a rather good agreement is ascertained.