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- Folker H. Wittmann, Z. P. Baztnt, +26 authors B. J. Trunk

A review of the basic theories of scaling in solid mechanics is presented. The problem of scaling is approached through dimensional analysis, laws of thermodynamics and asymptotic matching. Definitive conclusions on the relative importance of various sources of size effect (energy release, Weibull statistics, and crack fractality) tlrc drawn. The size… (More)

Modeling of the evolution of distributed damage such as microcracking, void formation, and softening frictional slip necessitates strain-softening constitutive models. The nonlocal continuum concept has emerged as an effective means for regularizing the boundary value problems with strain softening, capturing the size effects and avoiding spurious… (More)

- Mathieu Charlebois, M. Jirásek, Philippe Zysset
- Biomechanics and modeling in mechanobiology
- 2010

Using the three-dimensional morphological data provided by computed tomography, finite element (FE) models can be generated and used to compute the stiffness and strength of whole bones. Three-dimensional constitutive laws capturing the main features of bone mechanical behavior can be developed and implemented into FE software to enable simulations on… (More)

- Zdenek P. Bazant, Mark D. Adley, +5 authors Ferhun C. Caner
- 2000

The formulation of the microplane model for concrete and development of model M4 in the three preceding companion papers in this study is here extended to large strains. After giving examples of certain difficulties with the second Piola-Kirchhoff stress tensor in the modeling of strength and frictional limits on weak planes within the material, the… (More)

- M. Jirásek
- 2005

This paper deals with detennination of macroscopic fracture characteristics of random panicle systems. which represents a fundamental but little explored problem of micromechanics of quasibrittle materials. The panicle locations are randomly generated and the mechanical properties are characterized by a triangular softening forcedisplacement diagram for the… (More)

- Dale M. Atrens, Stephen M. Siviy, Lesley J. Holmes, Nadia Solowij, M. Jirásek
- Brain research bulletin
- 1987

The metabolic effects of electrical stimulation of the hypothalamus were investigated using indirect calorimetry. Stimulation of either the ventromedial hypothalamic nucleus (VMH) or the lateral hypothalamic area (LH) increased both respiratory quotient (RQ) and energy expenditure (EE) in 23 lightly anesthetized rats. The use of a muscle relaxant to reduce… (More)

- M. Jirásek
- 2005

The equivalent linear elastic fracture model based 0:;': an R-curve (a curve characterizing the variation of the critical energy release rate 'WIth the crack propagation length; IS generalized to describe both the rate effect and size effect observed in concrete. rock or other quasi brittle matenals. It is assumed that the crack propagation velocity depends… (More)

- Stephen M. Siviy, Dale M. Atrens, M. Jirásek, Lesley J. Holmes
- Alcohol
- 1987

The acute effects of ethanol and tertiary-butanol, an alcohol which is not metabolized via the alcohol dehydrogenase pathway, on whole body metabolism were studied using indirect calorimetry. Ethanol, but not t-butanol, increased energy expenditure in food-deprived rats. Both ethanol and t-butanol reduced respiratory quotient (RQ), an index of overall body… (More)

M. Jirasek Postdoctoral Research Fellow, Northwestern University, Evanston, IL A micromechanica/ly based enrichment of the nonlocal operator by a lerlll takillg into account the directional dependence of crack interactions (Ba~ant, 1992) can he expected to improve the performance of the non local model. The aim (d this paper is to examine this new model in… (More)

First it is shown by a simple one-dimensional example that stress-strain laws with softening cannot provide an objective description of response on the structural level. The phenomenon of discontinuous bifurcation from a uniform state is then analyzed in a general threedimensional setting. Localization conditions for isotropic damage models are derived in… (More)