Incubation time approach in rock fracture dynamics

Abstract

The paper is summarizing latest results connected with application of the incubation time approach to problems of dynamic fracture of rock materials. Incubation time based fracture criteria for intact media and media with cracks are discussed. Available experimental data on high rate fracture of different rock materials and incubation time based fracture criteria are used in order to evaluate critical parameters of causing fracture in these materials. Previously discovered possibility to optimize (minimize) energy input for fracture is discussed in connection to industrial rock fracture processes. It is shown that optimal value of momentum associated with critical load in order to initialize fracture in rock media does strongly depend on the incubation time and the impact duration. Existence of optimal load shapes minimizing momentum for a single fracturing impact or a sequence of periodic fracturing impacts is demonstrated.incubation time, dynamic fracture, rocks, dynamic strength, fracture toughness, crack resistance, energy and momentum input, fracture process optimization PACS number(s): 46.50.+a, 62.20.mm, 91.60.Ba Citation:Smirnov V, Petrov Y V, Bratov V. Incubation time approach in rock fracture dynamics.

Numerical simulation of ZrO2(Y2O3) ceramic plate penetration by cylindrical plunger

“…This opens a possibility to investigate the influence of the incubation time on behaviour of the fractured media. Reasonable range for possible incubation time variation was chosen keeping in mind values typical for other brittle materials [10]. Initial velocity of the plunger was another parameter that was alternated in course of simulations.…”

“…Incubation time fracture criterion [8] can be utilized for correct and robust prediction of critical conditions leading to fracture of material loaded by impact loads. In [9,10] this approach was successfully used to simulate dynamic fracture in other classes of quasi-brittle materials. It is supposed that a similar approach can be used to predict fracture initiation, evolution and arrest in ceramic materials [11] for the studied class of problems.…”

The preliminary heat treatment influence on the rock fracture toughness

“…В действительности оказалось, что механический отклик материалов на высокоскоростные нагрузки значительно отличается от случая статического нагружения [14]. Классические критерии разрушения, такие как критерий максимального напряжения для разрушения бездефектных сред и критерий трещиностойкости Ирвина для среды с трещинами, широко используемые для предсказания разрушения при статических и квазистатических нагрузках, не позволяли описать эффекты, наблюдаемые при ударных воздействиях [15]. Отличительными особенностями динамического разрушения являются экспериментально подтвержденные зависимость предельных значений параметров разрушения от вида и формы приложенной нагрузки [16], а также эффект «задержки» разрушения [17], при котором разрушение происходит после достижения в образце максимального значения напряжения, а не при пиковой нагрузке.…”

“…Инкубационное время является константой материала, характеризующей реакцию материала на динамические воздействия. Способ приложения нагрузки, форма импульса, геометрия образца не влияют на значения инкубационного времени [15].…”

Near-Resonant Regimes of a Moving Load on a Pre-Stressed Incompressible Elastic Half-Space

“…There are relatively few treatments of transient modes in moving load problems, including early works (Payton, 1967;Gakenheimer and Miklowitz, 1969) and also more recent contributions (de Hoop, 2002;Kaplunov et al, 2010b). It is known that an analysis of transient dynamics is generally non-trivial, often requiring a numerical approach; refer to studies by Bratov (2011) and Smirnov et al (2012). We also mention active studies of moving loads on elastic structures, for example refer to a textbook (Fryba, 1999) and references therein, as well as recent works in studies by Dimitrovová (2017), Wang et al (2020) and Lu et al (2020).…”