82 A. F. Fahem et al. 0 2 4 6 8 10 12 0 2 4 6 8 10 12 0 2 4 6 8 10 12 Rotation (deg.) J-Integral (N.mm-1) Stress intensity factor (MPa.m0.5) KI KII KIII J Fig. 13.8 Stress intensity factor of spirally notched PC specimen for β=67.5◦ Table 13.2 Fracture toughness result of Mixed-Mode PC (static case), β=67.5◦ Mode-I Mode-III Mixed-Mode(I/III) Mode-I [4] J-Integral Material KI MPa √m KIII MPa √m KI/IIIc MPa √m KIc MPa √m (J/m2) PC 4.85 1.65 5.264 4.1 10.1 13.4 Conclusion For a specific spiral v-notch specimen geometry, β =67.5◦, the Mixed-Mode fracture behavior of PC material is studied. A combined experimental-numerical method is used to calculate the Mixed-Mode (I/III) fracture toughness of elastic viscoplastic material for the combination of Mode I and Mode III conditions present near the notch tip when β =67.5◦. To obtain the baseline PC material properties, experiments are performed on dumbbell-shaped tension specimens. The experimental data for both the torsional load applied to the spiral v-notch specimen is used as input to calculate fracture toughness of the material. Results from the notched specimen study show that the notch tip is undergoing Mixed-Mode conditions, with KIc at the onset of fracture nearly 3X greater than KIIIc for β=67.5◦. Acknowledgments The support provided by the Ministry of Higher Education and Scientific Research, University of Al-Qadisiyah, College of Engineering, Mechanical Engineering Department, Iraq is greatly acknowledged. The support of the Department of Mechanical Engineering at the University of South Carolina and the Center for Mechanics, Materials, and NDE in the development and maintenance of the dynamic experimental equipment is deeply appreciated. The support of Dr. Jordan at the Air Force Office of Scientific Research and the Department of Defense DURIP program is gratefully appreciated. References 1. Faye, A., Basu, S., Parameswaran, V.: Effect of loading rate on dynamic fracture toghness of polycarbonate. Dyn. Behav. Mater., 139–145 (2014) 2. Cho, K., Yang, J.H., Kang, B.I., Park, C.E.: Notch sensitivity of polycarbonate and toughened polycarbonate. J. Appl. Polym. Sci. 89, 3115– 3121 (2003). https://doi.org/10.1002/app.12502 3. Gearing, B.P., Anand, L.: Notch-sensitive fracture of polycarbonate. Int. J. Solids Struct. 41, 827–845 (2004). https://doi.org/10.1016/ j.ijsolstr.2003.09.058 4. Salazar, A., Rodríguez, J., Martinez, A.B.: Fracture toughness reliability in polycarbonate: notch sharpening effects. Indian J. Mater. Sci. 2013, 1–4 (2013). https://doi.org/10.1155/2013/187802 5. LD, G.: Crazing, yielding, and fracture of polymers. I. Ductile brittle transition in polycarbonate. J. Appl. Polym. Sci. 13, 2129–2147 (2018) 6. Parvin, M., Williams, J.G.: Ductile-brittle fracture transitions in polycarbonate. Int. J. Fract. 11, 963–972 (1975). https://doi.org/10.1007/ BF00033842 7. Sundaram, B.M., Tippur, H.V.: Dynamic mixed-mode fracture behaviors of PMMA and polycarbonate. Eng. Fract. Mech. 176, 186–212 (2017)
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