A Constitutive Model for Jointed Rock Mass With Orthogonal Sets of Joints

1989 ◽  
Vol 56 (1) ◽  
pp. 25-32 ◽  
Author(s):  
E. P. Chen

The development and numerical implementation of a constitutive model for jointed rock media is the subject of investigation in this paper. The constitutive model is based on the continuum assumption of strain-partitioning among the elastic rock matrix and joint sets with nonlinear normal and shear responses. Rate equations for the stress-strain response of the jointed media have been formulated. A numerical incremental solution scheme to these equations has been developed. It has been implemented into the finite element code JAC as an additional material model. Several sample problems have been solved for demonstration purposes. Interpretation and discussion of these results are presented.

Author(s):  
Antony N. Beris ◽  
Brian J. Edwards

This much-needed monograph presents a systematic, step-by-step approach to the continuum modeling of flow phenomena exhibited within materials endowed with a complex internal microstructure, such as polymers and liquid crystals. By combining the principles of Hamiltonian mechanics with those of irreversible thermodynamics, Antony N. Beris and Brian J. Edwards, renowned authorities on the subject, expertly describe the complex interplay between conservative and dissipative processes. Throughout the book, the authors emphasize the evaluation of the free energy--largely based on ideas from statistical mechanics--and how to fit the values of the phenomenological parameters against those of microscopic models. With Thermodynamics of Flowing Systems in hand, mathematicians, engineers, and physicists involved with the theoretical study of flow behavior in structurally complex media now have a superb, self-contained theoretical framework on which to base their modeling efforts.


2014 ◽  
Vol 988 ◽  
pp. 502-507 ◽  
Author(s):  
Shao Bo Chai ◽  
Jian Chun Li ◽  
Hai Bo Li ◽  
Ya Qun Liu

According to the displacement discontinuity method and the conservation of momentum at the wave fronts, analysis for cylindrical P-wave propagation across a linear elastic rock joint is carried out. Considering the energy variation for wave propagation in one medium, the wave propagation equation was derived and expressed in an iterative form. The transmission and reflection coefficients are then obtained from the equation. By verification, the results agree very well with those from the existing results.


2021 ◽  
Vol 2090 (1) ◽  
pp. 012148
Author(s):  
G Frunzio ◽  
L Di Gennaro

Abstract The great interest about out of plane behavior of masonry infill walls has recently increased since it is a key point in the seismic modelling of framed structures. Their contribute to the whole seismic resistance of a framed building cannot be skipped. After a review of the literature on the subject, this paper presents a trilinear constitutive model for the out of plane behavior of masonry infills based on the tensile strength of the constituents. Comparisons with literature model are provided and the identification of the model is based on experimental tests.


2021 ◽  
pp. 1-32
Author(s):  
Ankit Agarwal ◽  
Marcial Gonzalez

Abstract We present a constitutive model for particle-binder composites that accounts for finite-deformation kinematics, nonlinear elasto-plasticity without apparent yield, cyclic hysteresis, and progressive stress-softening before the attainment of stable cyclic response. The model is based on deformation mechanisms experimentally observed during quasi-static monotonic and cyclic compression of mock Plastic-Bonded Explosives (PBX) at large strain. An additive decomposition of strain energy into elastic and inelastic parts is assumed, where the elastic response is modeled using Ogden hyperelasticity while the inelastic response is described using yield-surface-free endochronic plasticity based on the concepts of internal variables and of evolution or rate equations. Stress-softening is modeled using two approaches; a discontinuous isotropic damage model to appropriately describe the softening in the overall loading-unloading response, and a material scale function to describe the progressive cyclic softening until cyclic stabilization. A nonlinear multivariate optimization procedure is developed to estimate the elasto-plastic model parameters from nominal stress-strain experimental compression data. Finally, a correlation between model parameters and the unique stress-strain response of mock PBX specimens with differing concentrations of aluminum is identified, thus establishing a relationship between model parameters and material composition.


Humanities ◽  
2020 ◽  
Vol 9 (3) ◽  
pp. 96
Author(s):  
Bárbara Arizti

This paper focuses on Charlotte Wood’s 2015 dystopian novel The Natural Way of Things. Set in an unnamed place in the Australian outback, it recounts the story of 10 girls in their late teens and early twenties who are kept prisoners by a mysterious corporate organisation for their sexual involvement with an array of powerful men. The novel’s title invites two main readings: the first, and perhaps more obvious, along gender lines; and the second, which will provide the backbone to my analysis, within the framework of the natural world, the animal kingdom in particular. The Natural Way of Things has been described as a study in contemporary misogyny and the workings of patriarchy. The ingrained sexism of society—the insidious, normalised violence against females, often blamed on them, glossing over male responsibility—is undoubtedly the central topic of Wood’s work. Without losing sight of gender issues, my approach to Wood’s novel is inspired by Rosi Braidotti’s posthuman theories on the continuum nature–culture and the primacy of zoe—“the non-human, vital force of life”—over bios, or life as “the prerogative of Anthropos” (Rosi Braidotti). According to Braidotti, the current challenges to anthropocentrism question the distinction between these two forms of life, highlighting instead the seamless connection between the natural world and culture and favouring a consideration of the subject as embodied, nomadic and relational. My reading of The Natural Way of Things in light of Braidotti’s insights will be supplemented by an analysis of the novel in the context of transmodernity, both a period term and a distinct way of being in the world theorised by critics such as Rosa M. Rodríguez Magda and Marc Luyckx, who emphasise the relational, interdependent nature of contemporary times from a more human-centred perspective. The Natural Way of Things is also a story of female empowerment. This is especially the case with Yolanda Kovacs and Verla Learmont, the two protagonist women, who step out of their roles as victims and stand up to their guards. My analysis of the novel will revolve around these two characters and their different reactions to confinement and degradation. I conclude that although a more zoe-centred conception of the human subject that acknowledges the human–animal continuum should definitely be welcomed, literally “becoming animal”, as Yolanda does, deprives one of meaningful human relationality, embodied in the novel in Verla’s memories of her caring, empathic relationship with her father.


2017 ◽  
Vol 27 (10) ◽  
pp. 1482-1515 ◽  
Author(s):  
Lapo Gori ◽  
Samuel S Penna ◽  
Roque L da Silva Pitangueira

The present paper investigates the phenomenon of discontinuous failure (or localization) in elastic-degrading micropolar media. A recently proposed unified formulation for elastic degradation in micropolar media, defined in terms of secant tensors, loading functions and degradation rules, is used as a starting point for the localization analysis. Well-known concepts on acceleration waves propagation, such as the Maxwell compatibility condition and the Fresnel–Hadamard propagation condition, are derived for the considered material model in order to obtain a proper failure indicator. Peculiar problems are investigated analytically in details, in order to evaluate the effects on the onset of localization of two of the additional material parameters of the micropolar continuum, the Cosserat’s shear modulus and the internal bending length. Numerical simulations with a finite element model are also presented, in order to show the regularization behaviour of the micropolar formulation on the pathological effects due to the localization phenomenon.


2013 ◽  
Vol 483 ◽  
pp. 386-390
Author(s):  
Lei Song ◽  
Tong Su ◽  
Li Ying Gao ◽  
Qin He Zhang

In order to improve the accuracy of biopsy, an accurate FEM model is quite essential. To get the coefficients of the puncture target material which will be used in the Abaqus FEM analysis, the paper performed indentation test on gelatin phantom which is more stable than normal biological tissue. The Neo-Hookean and the improved Kelvin constitutive model were used to describe the mechanical properties of gelatin phantom demonstrated in the tests, including the hyperelastic and viscoelastic characteristics, then least squares method was used to fit the experimental data, finally the parameters of each constitutive model were achieved, which will be used to establish the material model in the further Abaqus FEM simulation.


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