Experimental and numerical study of dynamic fracture in polycarbonate
Anshul Faye (IIT Kanpur), Venkitanarayanan Parameswaran (IIT Kanpur), Sumit Basu (Indian Institute of Technology)
Dynamic Behavior of Materials
Tue 9:00 - 10:30
Salomon 101
Amorphous polymers have wide engineering applications in impact situations. Estimation of accurate dynamic fracture properties of these materials therefore become important for component design. For PMMA, which is a brittle amorphous polymer, effect of loading rates has largely been studied in literature and results indicate drastic increase in dynamic fracture toughness at higher loading rates compared to that under static loading conditions. Motivated by this observation, in the present work, another polymer named Polycarbonate (PC) is considered and dynamic fracture of PC at higher loading rates is studied. PC is an amorphous glassy polymer like PMMA, but it is ductile in nature, which is very different from PMMA. The objective of present work is also to investigate whether the behavior reported for PMMA is common for all glassy polymers. Towards this end, following a hybrid experimental and numerical approach, single-edge notched (SEN) specimen are subjected to 3-point bending in Hopkinson pressure bar. Accurate measurement of fracture initiation time in these experiments are facilitated by Ultra-high speed imaging (100000 fps). Using load-point displacement history from experiment as input, dynamic finite element simulations are performed using a well calibrated, realistic constitutive model for material. Dynamic J-integral is determined using domain integral method at fracture initiation time. High speed DIC technique is also used to get the actual notch-tip displacement fields in experiments and are compared with that from simulations. Study of notch-tip stress field provides additional information towards better understanding of dynamic fracture process in polymers. Results show that simulations are very well able to capture the displacement field near the notch-tip. No significant effect of loading rate is observed in dynamic fracture toughness for PC. Dynamic stress intensity factor (SIF) remain close to SIF at quasi-static loading.