Dynamic Caustics Experiments with Semi-Circular Specimen under Impact loading

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Journal of Vibration and Shock ›› 2016, Vol. 35 ›› Issue (9) : 52-58.

Li Qing, Guo Yang, MA Wanquan, WANG Mengyuan, Han Tong

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Abstract

The initiation and propagation of mode I and mixed mode I-II crack in Polymethylmethacrylate (PMMA) subjected to impact loading was studied by using dynamic caustics experimental system. It was shown that the initiation needed more energy from pure mode I to mixed mode I-II for PMMA, because the time-interval before crack initiation increased. The time-interval decreased from crack initiation to crack arrest, and it indicated that the average propagation velocity increased. Fracture toughness KIC of PMMA was 2.04 MN/m3/2 for mode I fracture. For mixed mode I-II fracture, the fracture toughness KIC was lower than one of mode I fracture, but the fracture toughness KIIC was higher. For mixed mode I-II fracture, the maximum propagation velocity PMMA was about 366m / s, then micro-cracks toughening phenomenon appeared at the crack tip. The surface energy of crack increased, and its propagation velocity decreased rapidly.

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impact fracture / dynamic caustics / fracture toughness / notched semi-circular bending specimen / preexisted crack

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Li Qing, Guo Yang, MA Wanquan, WANG Mengyuan, Han Tong. Dynamic Caustics Experiments with Semi-Circular Specimen under Impact loading[J]. Journal of Vibration and Shock, 2016, 35(9): 52-58

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