Micro-Mechanism of Dynamic Crack Propagation in Brittle Materials

Shioya, Tadashi; Koga, Yasutomo; Fujimoto, Koji; Ishida, Ryôhei

doi:10.1051/jphyscol:1988336

Cited by 8 publications

(6 citation statements)

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“…As mentioned above, the process of fracture of a non-cracked body consists of the following stages: initiation and formation of microcracks; coalescence of the microcracks and the formation of the initial cracks; autocatalytic propagation of the as-formed cracks, which can be arrested or can lead to the failure of a body [4,5,6]. The crack growth proceeds as follows [3][4][5][6][7]: under loading, one or more microcracks are formed in front of the crack tip.…”

Section: Analogy Between the Physical Mechanisms Of Fracture And Formmentioning

confidence: 99%

“…The crack growth proceeds as follows [3][4][5][6][7]: under loading, one or more microcracks are formed in front of the crack tip. Then, a microcrack joins the crack and that leads to crack growth.…”

Section: Analogy Between the Physical Mechanisms Of Fracture And Formmentioning

confidence: 99%

“…When the loaded body contains a crack (for example, if the initial crack has already been formed by the above described mechanism), the microcracks are formed not in the random points throughout the body, but just in the vicinity of a crack tip (it is determined by the stress concentration near the crack tip). In doing so, the density of the microcracks in the loaded body does not increase, since after the microcracks formation, they join the large crack [4,6]. It is of interest to compare the mechanisms of the formation of the initial and propagating crack with the two types of fractal objects: the fractal aggregates and the percolation clusters [15][16][17][18].…”

Section: Analogy Between the Physical Mechanisms Of Fracture And Formmentioning

confidence: 99%

“…T. Yokobori [3] used the analogy between fracture and phase transition as well, and applied the methods of statistical mechanics and phase transition theory to determine the crack velocity. It is known that the process of fracture consists of several stages: the formation of damage (microcracks) in the random points of a loaded body; the coalescence of the microcracks and the formation of initial cracks; the growth of the initial cracks, until one of the cracks becomes the largest and propagates with increasing velocity; the breakdown of the body or arrest of the crack [4][5][6][7][8]. Usually, the different theoretical methods are applied to model these stages: for example, the growth of a large crack can be modeled by the methods of fracture mechanics; the damage evolution is studied with the use of continuum damage mechanics [9], etc.…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Determination for the time-to-fracture of solids

Mishnaevsky

1996

Int J Fract

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Section: Analogy Between the Physical Mechanisms Of Fracture And Formmentioning

confidence: 99%

Section: Analogy Between the Physical Mechanisms Of Fracture And Formmentioning

confidence: 99%

Section: Analogy Between the Physical Mechanisms Of Fracture And Formmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Determination for the time-to-fracture of solids

Mishnaevsky

1996

Int J Fract

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“…For all δ ≥ δc, α=1/3.In amorphous and heterogeneous materials, crack growth involves complex interplay of micro-crack nucleation, growth and coalescence [1]. In these materials the process of fracture exhibits typically the following three stages: (i) initiation and formation of the micro cracks at soft points of the sample, (ii) coalescence of the micro-cracks and (iii) the propagation of the as-formed cracks [2]. When there are no large cracks, the breaking takes place randomly throughout the body, independent of each other, similar to what happens in a percolation process.…”

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confidence: 99%

Failure time in heterogeneous systems

Roy

Biswas

Ray

2019

Phys. Rev. Research

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We show that the failure time τ f in fiber bundle model, taken as a prototype of heterogeneous materials, depends crucially on the strength of the disorder δ and the stress release range R in the system. For R beyond a critical value Rc the distribution of τ f follows Weibull form. In this region, the average τ f shows the variation τ f ∼ L α where L is the system size. For R < Rc, τ f ∼ L/R. We find that the crossover length scale has the scaling form Rc ∼ L 1−α . This scaling has been found to be valid for various disorder distributions. For δ < δc, α is an increasing function of δ. For all δ ≥ δc, α=1/3.In amorphous and heterogeneous materials, crack growth involves complex interplay of micro-crack nucleation, growth and coalescence [1]. In these materials the process of fracture exhibits typically the following three stages: (i) initiation and formation of the micro cracks at soft points of the sample, (ii) coalescence of the micro-cracks and (iii) the propagation of the as-formed cracks [2]. When there are no large cracks, the breaking takes place randomly throughout the body, independent of each other, similar to what happens in a percolation process. When the micro-crack density becomes large, they coalesce and form an initial crack. At this point, the micro-cracks tend to form in the vicinity of the crack tip (determined by the stress concentration and disorder). The large crack then grows (like that in a nucleation process) and the density of micro-cracks in the sample starts decreasing as more and more micro-cracks join the large crack. Recent studies have paid lots of attention on when the fracture will be percolating type and when it will be of nucleating type [3,4]. While these steps eventually leads to fracture, each of them takes finite time to complete, the estimates of which are crucial regarding the stability and safety of a disordered sample.The time to fracture, τ f , at a particular load, is an outcome of this spatial and temporal micro cracking dynamics mentioned above. It is defined to be the time taken for the system to fracture under a certain loading condition. It is very important from the point of view of understanding failure of a specimen and engineering design and reliability [5][6][7][8][9][10]. Many models have been proposed to predict the failure time [9,[11][12][13][14][15][16]. However most models and studies are concerned with the dependence of τ f on applied load or on the macroscopic parameters like temperature, pressure, considering the crack growth as an activation process [10,13]. The understanding of the failure time from the microscopic fracture dynamics, specially in heterogeneous materials, has remained unclear [17,18].Time to failure of a mechanical system consisting of parallel members have been studied in the past [19,20]. These studies mostly has the order statistics of the failure time distribution for a single member. Damage evo-lution and time to failure have been investigated in a model where the damage formation is a stochastic event with the probability of f...

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Experimental investigation of the dynamic fracture of a class of RT-PMMAs under impact loading

Jali

Longère

2020

Int J Fract

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The present work aims to investigate experimentally the crack arrest capability and dynamic fracture mechanisms under impact loading of three commercial, rubber-toughened (RT) PMMA grades differing by their rubber nano-particle concentration and resulting Charpy impact toughness. For that purpose, Kalthoff and Winkler (KW)-like impact tests were performed using gas launcher considering impact velocities ranging between 20 and 100 m/s. A high-speed camera was used to record the projectile/specimen interaction and the progressive failure of the specimen. The fracture surfaces of the fragments were observed using a scanning electron microscope (SEM). It is seen that the higher the impact velocity the larger the number of fragments. On the other hand, it is shown that increasing the rubber nano-particle concentration favors the crack arrest capability under impact loading by promoting inelastic deformation, reducing the crack propagation velocity, limiting crack multi-branching, and reducing the number of fragments.

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Micro-Mechanism of Dynamic Crack Propagation in Brittle Materials

Cited by 8 publications

References 0 publications

Determination for the time-to-fracture of solids

Determination for the time-to-fracture of solids

Failure time in heterogeneous systems

Experimental investigation of the dynamic fracture of a class of RT-PMMAs under impact loading

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