Temperature and strain-rate dependence of fracture toughness of phenolphthalein polyether ketone

✍ Scribed by Yanchun Han; Yuming Yang; Binyao Li; Zhiliu Feng

• Publisher: Springer
• Year: 1995
• Tongue: English
• Weight: 389 KB
• Volume: 30
• Category: Article
• ISSN: 0022-2461
• DOI: 10.1007/bf00351881

✦ Synopsis

A strong strain-rate and temperature dependence was observed for the fracture toughness of phenolphthalein polyether ketone (PEK-C). Two separate crack-blunting mechanisms have been proposed to account for the fracture-toughness data. The first mechanism involves thermal blunting due to adiabatic heating at the crack tip for the high temperatures studied. In the high-temperature range, thermal blunting increases the fracture toughness corresponding to an effectively higher test temperature. However, in the low-temperature range, the adiabatic temperature rise is insufficient to cause softening and J~c increases with increasing temperature owing to viscoelastic losses associated with the J3-relaxation there. The second mechanism involves plastic blunting due to shear yield/flow processes at the crack tip and this takes place at slow strain testing of the single-edge notched bending (SENB) samples. The temperature and strain-rate dependence of the plastic zone size may also be responsible for the temperature and strain-rate dependence of fracture toughness.