Crack motion in viscoelastic solids: The role of the flash temperature |
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Authors: | Email author" target="_blank">G?CarboneEmail author B?N?J?Persson |
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Institution: | (1) DIMeG-Politecnico di Bari, V.le Japigia 182, 70126 Bari, Italy;(2) IFF Forschungszentrum Jülich, 52425 Jülich, Germany;(3) CEMeC-Politecnico di Bari, Via Re David 200, 70125 Bari, Italy |
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Abstract: | We present a simple theory of crack propagation in viscoelastic solids. We calculate the energy per unit area, G(v), to propagate a crack, as a function of the crack tip velocity v. Our study includes the non-uniform temperature distribution (flash temperature) in the vicinity of the crack tip, which has a profound influence on G(v). At very low crack tip velocities, the heat produced at the crack tip can diffuse away, resulting in very small temperature increase: in this “low-speed” regime the flash temperature effect is unimportant. However, because of the low heat conductivity of rubber-like materials, already at moderate crack tip velocities a very large temperature increase (of order of 1000 K) can occur close to the crack tip. We show that this will drastically affect the viscoelastic energy dissipation close to the crack tip, resulting in a “hot-crack” propagation regime. The transition between the low-speed regime and the hot-crack regime is very abrupt, which may result in unstable crack motion, e.g. stick-slip motion or catastrophic failure, as observed in some experiments. In addition, the high crack tip temperature may result in significant thermal decomposition within the heated region, resulting in a liquid-like region in the vicinity of the crack tip. This may explain the change in surface morphology (from rough to smooth surfaces) which is observed as the crack tip velocity is increased above the instability threshold. |
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Keywords: | 46 50 +a Fracture mechanics fatigue and cracks 83 60 Bc Linear viscoelasticity 46 55 +d Tribology and mechanical contacts |
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