Crack instability of ferroelectric solids under alternative electric loading |
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| Affiliation: | 1. Department of Engineering Mechanics, Tsinghua University, Beijing 100084, PR China;2. LTCS and College of Engineering, Peking University, Beijing 100871, PR China;3. LNM, Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190, PR China;1. Harbin Institute of Technology, 150080 Harbin, China;2. Katholieke Universiteit Leuven, 3001 Leuven, Belgium;3. Changchun University of Technology, 130000 Changchun, China;1. Institute of Civil Engineering, Ecole Polytechnique Fédérale of Lausanne (EPFL), Lausanne, Switzerland;2. Materials Science Institute, Ecole Polytechnique Fédérale of Lausanne (EPFL), Lausanne, Switzerland;1. Department of Mechanical and Aerospace Engineering, University of Rome La Sapienza, Via Eudossiana 18, Rome 00184, Italy;2. Department of Chemical Engineering Materials Environment, University of Rome La Sapienza, Via Eudossiana 18, Rome 00184, Italy;1. Department of Mechanical Engineering and Science, Kyoto University, Yoshidahommachi, Sakyo-ku, Kyoto, 606-8501, Japan;2. Institute of System Engineering, China Academy of Engineering Physics, Mianyang, 621900, China;1. Department of Electrical Engineering, Changwon National University, Gyeongnam 641-773, Republic of Korea;2. Department of Mechanical Engineering, Changwon National University, Gyeongnam 641-773, Republic of Korea |
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| Abstract: | The low fracture toughness of the widely used piezoelectric and ferroelectric materials in technological applications raises a big concern about their durability and safety. Up to now, the mechanisms of electric-field induced fatigue crack growth in those materials are not fully understood. Here we report experimental observations that alternative electric loading at high frequency or large amplitude gives rise to dramatic temperature rise at the crack tip of a ferroelectric solid. The temperature rise subsequently lowers the energy barrier of materials for domain switch in the vicinity of the crack tip, increases the stress intensity factor and leads to unstable crack propagation finally. In contrast, at low frequency or small amplitude, crack tip temperature increases mildly and saturates quickly, no crack growth is observed. Together with our theoretical analysis on the non-linear heat transfer at the crack tip, we constructed a safe operating area curve with respect to the frequency and amplitude of the electric field, and validated the safety map by experiments. The revealed mechanisms about how electro-thermal-mechanical coupling influences fracture can be directly used to guide the design and safety assessment of piezoelectric and ferroelectric devices. |
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| Keywords: | Electro-thermal-mechanical coupling Crack instability Ferroelectric materials Safe operating area |
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