Instability of critical characteristics of crack propagation
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O R I G I NA L PA P E R
Y. V. Petrov · A. V. Cherkasov · N. A. Kazarinov
Instability of critical characteristics of crack propagation
Received: 9 July 2020 / Revised: 23 September 2020 / Accepted: 2 October 2020 © Springer-Verlag GmbH Austria, part of Springer Nature 2020
Abstract The paper presents the numerically evaluated dependence of the stress intensity factor (SIF) on crack velocity (K I − a˙ dependence) in Homalite-100 specimens subjected to pulse loading. Experiments on crack propagation (Ravi-Chandar and Knauss in Int J Fract 25:247–262, 1984. https://doi.org/10.1007/BF00963460; Int J Fract 26:65–80, 1984. https://doi.org/10.1007/BF01152313; Int J Fract 26:141–154, 1984. https://doi. org/10.1007/BF01157550; Int J Fract 26:189–200, 1984. https://doi.org/10.1007/bf01140627) were simulated using the finite element method and incubation time fracture criterion. According to (Ravi-Chandar and Knauss in Int J Fract 26:141–154, 1984. https://doi.org/10.1007/BF01157550), experimental data on the SIF–crack velocity dependence exhibit unstable behavior, i.e. considerable scattering of the SIF values: a broad range of SIF values corresponds to a single crack velocity. This way, the conventional approach based on a K I − a˙ dependence being a material property is not applicable in this case. Such a phenomenon is also observed in a numerically obtained K I − a˙ dependence, meaning that the developed approach makes it possible to evade the known ambiguity of the K I − a˙ relation to predict the crack propagation.
1 Introduction Dynamic crack propagation due to dynamic loading is of high importance for both engineering applications and fundamental research, since it reveals a variety of effects that cannot be explained or predicted within the framework of classic fracture mechanics. Special attention is usually paid to the conditions of the crack movement initiation as the crack onset usually results in catastrophic loss of the structure’s bearing capacity [5]. Following contemporary approaches to the dynamic crack propagation problems, classic energy fracture criteria [6] are extended to the dynamic case. For example, Irwin’s fracture criterion K I ≥ K I c is used to study hydraulic fracturing problems using expressions for the current SIF which account for shear stresses [7]. Some approaches imply replacement of static ultimate parameters with functional dependencies (on time, loading rate, crack velocity), which are regarded as material properties to be evaluated experimentally [8]. Unfortunately, these methods can possibly lead to ambiguities since the involved functionals can be nonunique or even nonexistent [3,9]. Y. V. Petrov (B) · A. V. Cherkasov Saint Petersburg State University, Saint Petersburg, Russia 199034 E-mail: [email protected] Y. V. Petrov · N. A. Kazarinov Institute of Problems of Mechanical Engineering, Saint Petersburg, Russia 199178 N. A. Kazarinov Emperor Alexander I Saint Petersburg State Transport University, Saint Petersburg, Russia 190031
Y. V. Petrov et al.
Fig. 1 Temporal dependenc
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