The Effect of Disorder on Crackling Noise in Fracture Phenomena (original) (raw)
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Crackling noise in sub-critical fracture of heterogeneous materials
Journal of Statistical Mechanics: Theory and Experiment, 2009
We present a theoretical study of the sub-critical fracture of heterogeneous materials under a constant external load. A generic fiber bundle model is proposed, which provides a direct connection between the microscopic fracture mechanisms and the macroscopic time evolution of the sub-critical system. In the model, material elements either fail due to immediate breaking or undergo a damage accumulating ageing process. On the macrolevel the model reproduces the empirical Basquin law of rupture life, and it makes it possible to derive a generic scaling form for the deformation histories of different load values. On the microlevel we found that sub-critical fracture is accompanied by crackling noise, i.e. the competition of the two failure modes of fibers gives rise to a complex bursting activity, where slow damage sequences trigger bursts of breaking events. When the load is equally distributed over the fibers, the size of damage sequences and of bursts, as well as the waiting times in between, are characterized by universal power law distributions, where only the cutoffs have material dependence. When stress concentrations arise in the vicinity of failed regions, the power law distributions of noise characteristics prevail but the exponents are different from their equal load sharing counterparts. In the presence of stress concentration the failure process accelerates resulting in a higher value of the waiting time exponent compared to the case of homogeneous stress distribution.
Crackling noise in three-point bending of heterogeneous materials
Physical Review E, 2011
We study the crackling noise emerging during single crack propagation in a specimen under threepoint bending conditions. Computer simulations are carried out in the framework of a discrete element model where the specimen is discretized in terms of convex polygons and cohesive elements are represented by beams. Computer simulations revealed that fracture proceeds in bursts whose size and waiting time distributions have a power law functional form with an exponential cutoff. Controlling the degree of brittleness of the sample by the amount of disorder, we obtain a scaling form for the characteristic quantities of crackling noise of quasi-brittle materials. Analyzing the spatial structure of damage we show that ahead of the crack tip a process zone is formed as a random sequence of broken and intact mesoscopic elements. We characterize the statistics of the shrinking and expanding steps of the process zone and determine the damage profile in the vicinity of the crack tip.
Crackling Dynamics in Material Failure as the Signature of a Self-Organized Dynamic Phase Transition
Physical Review Letters, 2008
We derive here a linear elastic stochastic description for slow crack growth in heterogeneous materials. This approach succeeds in reproducing quantitatively the intermittent crackling dynamics observed recently during the slow propagation of a crack along a weak heterogeneous plane of a transparent Plexiglas block [Mly et al., PRL 96 045501]. In this description, the quasi-static failure of heterogeneous media appears as a self-organized critical phase transition. As such, it exhibits universal and to some extent predictable scaling laws, analogue to that of other systems like for example magnetization noise in ferromagnets.
Fluctuations of Global Energy Release and Crackling in Nominally Brittle Heterogeneous Fracture
Physical Review Letters, 2014
The temporal evolution of mechanical energy and spatially-averaged crack speed are both monitored in slowly fracturing articial rocks. Both signals display an irregular burst-like dynamics, with power-law distributed uctuations spanning a broad range of scales. Yet, the elastic power released at each time step is proportional to the global velocity all along the process, which enables dening a material-constant fracture energy. We characterize the intermittent dynamics by computing the burst statistics. This latter displays the scale-free features signature of crackling dynamics, in qualitative but not quantitative agreement with the depinning interface models derived for fracture problems. The possible sources of discrepancies are pointed out and discussed.
Phase transitions and correlations in fracture processes where disorder and stress compete
Physical Review Research, 2020
We study the effect of the competition between disorder and stress enhancement in fracture processes using the local load sharing fiber bundle model, a model that hovers on the border between analytical tractability and numerical accessibility. We implement a disorder distribution with one adjustable parameter. The model undergoes a localization transition as a function of this parameter. We identify an order parameter for this transition and find that the system is in the localized phase over a finite range of values of the parameter bounded by a transition to the non-localized phase on both sides. The transition is first order at the lower transition and second order at the upper transition. The critical exponents characterizing the second order transition are close to those characterizing the percolation transition. We determine the spatiotemporal correlation function in the localized phase. It is characterized by two power laws as in invasion percolation. We find exponents that are consistent with the values found in that problem.
Crackling versus Continuumlike Dynamics in Brittle Failure
Physical Review Letters, 2013
We study how the loading rate, specimen geometry and microstructural texture select the dynamics of a crack moving through an heterogeneous elastic material in the quasi-static approximation. We find a transition, fully controlled by two dimensionless variables, between dynamics ruled by continuum fracture mechanics and crackling dynamics. Selection of the latter by the loading, microstructure and specimen parameters is formulated in terms of scaling laws on the power spectrum of crack velocity. This analysis defines the experimental conditions required to observe crackling in fracture. Beyond failure problems, the results extend to a variety of situations described by models of the same universality class, e.g. the dynamics in wetting or of domain walls in amorphous ferromagnets.
Crackling Noise in Disordered Materials
Annual Review of Condensed Matter Physics, 2014
Recent experimental and theoretical progress on the study of crackling noise in the plastic deformation of crystals, ferroelastics, and porous materials is reviewed. We specifically point out opportunities and potential pitfalls in this approach to the study of the nonequilibrium dynamics of disordered materials. Direct optical observation of domain boundary movement under stress and experimental results from acoustic emission and heat-flux measurements lead to powerlaw scaling of the jerk distribution with energy exponents between 1.3 and 2.3. The collapse of porous materials under stress leads to exceptionally large intervals of power-law scaling (seven decades). Applications in geology and materials sciences are discussed. 233 Annu. Rev. Condens. Matter Phys. 2014.5:233-254. Downloaded from www.annualreviews.org by 86.6.154.247 on 04/15/14. For personal use only.
The effect of disorder on the fracture nucleation process
Physica D-nonlinear Phenomena, 2001
The statistical properties of failure are studied in a fiber bundle model with thermal noise. We show that the macroscopic failure is produced by a thermal activation of microcracks. Most importantly the effective temperature of the system is amplified by the spatial disorder (heterogeneity) of the fiber bundle. The case of a time dependent force and the validity of the Kaiser effects are also discussed. These results can give more insight to the recent experimental observations on thermally activated crack and can be useful to study the failure of electrical networks.
Journal of Statistical Mechanics: Theory and Experiment, 2009
We discuss the results of a series of experiments performed on heterogeneous materials where we have measured the acoustic emission (AE) signals preceding macroscopic failure that correspond to precursory rupture events. We mainly focus on polyurethane foams whose heterogeneities (pores) constitute arrest points for microcracks. The released AE energy is always power law distributed independently of the material porosity, the loading history (creep and tensile) and the mechanical properties (from brittle to ductile with increasing temperature). This is also the case for time intervals between events except in tensile tests when the material is brittle. We also highlight two key physical behaviors. The first is the occurrence of a unique behavior for a cumulative number of events and the cumulative energy in creep tests. The second is that the statistical properties are more influenced by the mechanical behavior than the microstructure of the material. Finally we discuss the problems which are still open for connecting these results with theoretical modeling of AE.