Continuous Damage of Brittle Solids

Najar, J.

doi:10.1007/978-3-7091-2806-0_7

Cited by 23 publications

(31 citation statements)

References 8 publications

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“…It is visibly localised in the vicinity of the spalled cross section, where the number of energy sinks grows due to the dynamic wave interactions on the microstructural level of the material. This process can be phenomenologically best described in terms of a continuum damage response, [9], and it should be coupled with random and deterministic distributions of inhomogeneities of material characteristics within the specimen, [10,16]. An outline of this approach is presented in Sec.…”

Section: Basic Experimental Results At Room Temperaturementioning

confidence: 99%

“…As long as the fundamental feature of the alumina ceramics, which is their inhomogeneity, is not properly accounted for, the description lacks the ability to re¯ect our experimental observations on tensile failure at spall. The proper way seems to be, therefore, to introduce a sound mix of random and deterministic inhomogeneities, and to apply to the mesoscale elements the brittle-elastic continuum damage description proposed in [9,10]. A short account on this procedure is given in Sec.…”

Section: Introductionmentioning

confidence: 99%

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Enhanced fracture energy and effects of temperature at spalling in ceramics: continuum damage modelling

Najar

Silberschmidt

Müller-Bechtel³

2000

Archive of Applied Mechanics (Ingenieur Archiv)

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Enhanced fracture energy losses at spalling and the temperature dependence of the spalling strength of alumina ceramic bars are analysed on the basis of the experimental tests conducted both in room temperature and within the temperature range up to 1500°C at strain rates of some 500 s )1 . The experimental method and the measurements are ®rst shortly outlined. The mechanical response of ceramic bars is modelled then as a heterogeneous distribution of brittle-elastic mesoelements undergoing continuum damage at the known strain history, corresponding to that registered in the experiments. The mesoelements are characterised by the values of initial damage randomly¯uctuating within a given band-width superposed on a deterministic distribution, which corresponds to the fabrication conditions of the ceramic bars. The model has been tested in the evaluation of room-temperature experiments, its parameters: the average value of the initial damage, Young's modulus of the undamaged material and the energy absorption capacity in continuum damage are taken from the calibration ®tting the experimental data. The registered energy losses at spalling, which exceed the static values of fracture energy by almost an order of magnitude, can be explained thus by the enhancement of the dissipation due to bulk damage, which is computed on the basis of the above parameters. The temperature change of the Young's modulus of the matrix material is taken as corresponding to the measured change of the uniaxial wave velocity in the bar, and corrected by the temperature change of the mass density. The analysis of the model shows that the drop in the spalling strength of the specimens with the increase of the temperature is phenomenologically related to the falling energy absorption capacity within the continuum damage mechanism. An explanation of this phenomenon is attempted, based on the grain-sizerelated mechanisms of the microfracture from pre-existing intergranular¯aws distributed over the bulk of ceramics.

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Section: Basic Experimental Results At Room Temperaturementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Enhanced fracture energy and effects of temperature at spalling in ceramics: continuum damage modelling

Najar

Silberschmidt

Müller-Bechtel³

2000

Archive of Applied Mechanics (Ingenieur Archiv)

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“…The failure mechanism of some brittle materials, such as ceramics and concrete, is characterized by only minor plastic flow, and is dominated by degradation of material properties due to nucleation, growth and coalescence of microcracks [14,15]. Furthermore, the resulting propagation of large cracks usually takes place at a significantly higher rate and constitutes a small portion of the fatigue life.…”

Section: Failure By Accumulation Of Distributed Damagementioning

confidence: 98%

Fatigue life prediction using 2‐scale temporal asymptotic homogenization

Oskay

Fish

2004

Numerical Meth Engineering

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SUMMARYIn this manuscript, fatigue of structures is modelled as a multiscale phenomenon in time domain. Multiple temporal scales are introduced due to the fact that the load period is orders of magnitude smaller than the useful life span of a structural component. The problem of fatigue life prediction is studied within the framework of mathematical homogenization with two temporal co-ordinates. By this approach the original initial boundary value problem is decomposed into coupled micro-chronological (fast time-scale) and macro-chronological (slow time-scale) problems. The life prediction methodology has been implemented in ABAQUS and validated against direct cycle-by-cycle simulations.

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“…In the literature, a variety of models employing exponential laws for mechanical damage growth have been successful in matching experiments, see for example [13]. With this in mind, an expedient model is:…”

Section: Phenomenological Degradationmentioning

confidence: 99%

Phenomenological modeling and numerical simulation of the environmental degradation of multiphase engineering materials

Zohdi¹,

Wriggers²

2000

Archive of Applied Mechanics (Ingenieur Archiv)

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In this paper a coupled thermodynamical/chemical/mechanical model is developed to simulate the time dependent degradation of heterogeneous solid materials subjected to corrosive environments. The model, which is based on a description of the microscale, employs the ®rst law of thermodynamics, a mass balance of a diffusing corrosive species, and a balance of momentum. The presence of the corrosive species is phenomenologically modeled as irreversibly reducing the material stiffness, dependent on the amount and time present. Numerical experiments are given to illustrate some characteristics of the model.

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Continuous Damage of Brittle Solids

Cited by 23 publications

References 8 publications

Enhanced fracture energy and effects of temperature at spalling in ceramics: continuum damage modelling

Enhanced fracture energy and effects of temperature at spalling in ceramics: continuum damage modelling

Fatigue life prediction using 2‐scale temporal asymptotic homogenization

Phenomenological modeling and numerical simulation of the environmental degradation of multiphase engineering materials

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