Evaluation of methods of determining fracture parameters for a glassy polymer: Poly(methyl methacrylate)

✍ Scribed by Bryan Ellis; A. J. Hare; Richard Van Noort

• Publisher: John Wiley and Sons
• Year: 1985
• Tongue: English
• Weight: 602 KB
• Volume: 30
• Category: Article
• ISSN: 0021-8995
• DOI: 10.1002/app.1985.070301202

✦ Synopsis

Fracture criteria for the brittle fracture of a glassy thermoplastic, poly(methy1 methacrylate), have been evaluated using three test piece geometries; the double cantilever beam (DCB), threepoint bend (TPB), and compact tension (Cl'). For the DCB good agreement is obtained with published estimates of the fracture parameters using either a compliance calibration calculation for the critical energy release rate, Glc, or a polynomial function for the critical streas intensity factor, Klc. Anamolously high values of G,. or K,, were obtained using the TPB test piece. These high values of K,, max be partially due to the difficulty of "sharpening" the crack, but there is a test piece size effect which also contributes to the over estimation of Klc. For the Cl' test piece use of either a new compliance calibration for the determination of GI, or a standard polynomial function for K,,, good agreement was obtained with our own DCB and other published data. "he range of applicability of the CT test geometry is discussed critically, and with some reservations it is considered suitable for the evaluation of either Gl, or Klc.