• Computers and Concrete
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• 제7권4호
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• pp.365-386
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• 2010

This paper presents the physical formulation of a 1D material model suitable for seismic applications. It is written within the framework of thermodynamics with internal variables that is, especially, very efficient for the phenomenological representation of material behaviors at macroscale: those of the representative elementary volume. The model can reproduce the main characteristics observed for concrete, that is nonsymetric loading rate-dependent (viscoelasticity) behavior with appearance of permanent deformations and local hysteresis (continuum plasticity), stiffness degradation (continuum damage), cracking due to displacement localization (discrete plasticity or damage). The parameters have a clear physical meaning and can thus be easily identified. Although this point is not detailed in the paper, this material model is developed to be implemented in a finite element computer program. Therefore, for the benefit of the robustness of the numerical implementation, (i) linear state equations (no local iteration required) are defined whenever possible and (ii) the conditions in which the presented model can enter the generalized standard materials class - whose elements benefit from good global and local stability properties - are clearly established. To illustrate the capabilities of this model - among them for Earthquake Engineering applications - results of some numerical applications are presented.

• 한국공작기계학회논문집
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• 제14권3호
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• pp.103-109
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• 2005

Since fretting fatigue damage accumulation occurs over relatively small volumes, the role of the microstructure is quite significant in fretting fatigue analysis. The heterogeneity of discrete grains and their crystallographic orientation can be accounted for using continuum crystallographic cyclic plasticity models. Such a constitutive law used in parametric studies of contact conditions may ultimately result in more thorough understanding of realistic fretting fatigue processes. The primary focus of this study is to explore the influence of microstructure as well as the magnitude of the normal force and tangential force amplitude during the fretting fatigue process. Fretting maps representing cyclic plastic strain behaviors are also developed to shed light on the cyclic deformation mechanisms.