Anil Misra

Anil Misra
University of Kansas | KU · Department of Civil, Environmental and Architectural Engineering

Ph.d.

About

277
Publications
44,988
Reads
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7,751
Citations
Citations since 2016
100 Research Items
5283 Citations
201620172018201920202021202202004006008001,000
201620172018201920202021202202004006008001,000
201620172018201920202021202202004006008001,000
201620172018201920202021202202004006008001,000
Additional affiliations
January 2008 - present
University of Kansas
Position
  • Managing Director
January 2008 - present
University of Kansas
Position
  • Professor
September 1990 - December 2007
University of Missouri - Kansas City
Position
  • Professor

Publications

Publications (277)
Article
Constitutive equations for class of materials that possess granular microstructure can be effectively derived using granular micromechanics approach. The stress–strain behavior of such materials depends upon the underlying grain scale mechanisms that are modeled by using appropriate rate-dependent inter-granular force–displacement relationships. Th...
Article
The mechanical behavior of monolithic cementitious materials is known to be significantly affected by their granular nature. This paper describes an approach to incorporate the effects of granularity for cementitious material based upon the granular micromechanics paradigm and thermomechanics. As a result, macro-scale constitutive equations that ut...
Article
Granular materials are typically characterized by complex structure and composition. Continuum modeling, therefore, remains the mainstay for describing properties of these material systems. In this paper, we extend the granular micromechanics approach by considering enhanced kinematic analysis. In this analysis, a decomposition of the relative move...
Article
Biaxial experiments are performed with rod assemblies to study the micro-mechanical deformation behavior of granular materials. The focus of these experiments is upon the micromechanical behavior under mixed boundary conditions, with stress-controlled lateral boundaries and displacement-controlled axial boundaries. Particle motions, i.e. displaceme...
Article
For many problems in science and engineering, it is necessary to describe the collective behavior of a very large number of grains. Complexity inherent in granular materials, whether due the variability of grain interactions or grain-scale morphological factors, requires modeling approaches that are both representative and tractable. In these cases...
Article
This paper aims at modelling pull-out tests of a reinforcement bar from a concrete matrix. The considered system is an elastic cylinder, within which is embedded a rigid bar placed along the central axis. The pull-out test consists in extracting the bar while fixing the outer lateral boundary of the cylinder. Typically, the concrete matrix would be...
Article
Chiral effects in 2D Cosserat continuum model may arise from coupling between stretching deformations and the micro-rotation for hemitropic materials. An orthotropic 2D chiral Cosserat continuum is introduced to account for this type of coupling. The expected chiral effects are verified through an experimental effort using a specimen with granular...
Article
Full-text available
By 2060, nearly 100 million people in the U.S. will be over age 65 years. One-third of these older adults will have root caries, and nearly 80% will have dental erosion. These conditions can cause pain and loss of tooth structure that interfere with eating, speaking, sleeping, and quality of life. Current treatments for root caries and dental erosi...
Article
Full-text available
The low-viscosity adhesive that is used to bond composite restorative materials to the tooth is readily damaged by acids, enzymes, and oral fluids. Bacteria infiltrate the resulting gaps at the composite/tooth interface, demineralize the tooth, and further erode the adhesive. This paper presents the preparation and characterization of a low-crossli...
Article
In a previous work, we have shown that a granular micromechanics approach can lead to load path dependent continuum models. In the present work, we generalize such a micromechanical approach introducing an intrinsic 2nd gradient energy storage mechanism (resembling pantographic micromechanism), in the grain-grain interaction. Such a mechanism, repr...
Article
Full-text available
We report a continuum theory for 2D strain gradient materials accounting for a class of dissipation phenomena. The continuum description is constructed by means of a (reversible) placement function and by (irreversible) damage and plastic functions. Besides, expressions of elastic and dissipation energies have been assumed as well as the postulatio...
Article
The recent wide-ranging interest in chiral materials motivates the need to understand the mechanisms that underlie mechanical chirality. This paper investigates the emergent chiral mechanical behavior of bars in relationship to microscale deformation mechanisms. The focus is upon (meta)material systems with granular motif that exploit couplings bet...
Article
A general framework to derive nonlinear elastic and elastoplastic material models from granular micromechanics is proposed, where a constraint-based variational structure is introduced to classical grain contact-based homogenization methods of hyperelasticity. Like the classical hyperelastic methods, reference solutions for closed-form hyperelastic...
Chapter
By 2030, the National Institutes of Health predicts that 72 million Americans will be 65 and older − and nearly 80% of them will suffer a chronic health condition that requires tissue, joint, or organ repair. Biomaterials will be key to meeting this demand. Biomaterials are used in millions of medical devices including implants, stents, catheters,...
Article
We analyze in two dimensions the mechanical behavior of materials with granular microstructures modeled by means of a vari-ationally formulated strain-gradient continuum approach based on micromechanics and show that it can capture microstructural-size-dependent effects. Tension-compression asymmetry of grain-assembly interactions, as well as micro...
Article
Full-text available
This paper is devoted to the development of a continuum theory for materials having granular microstructure and accounting for some dissipative phenomena like damage and plasticity. The continuum description is constructed by means of purely mechanical concepts, assuming expressions of elastic and dissipation energies as well as postulating a hemi-...
Article
Full-text available
Describing the emerging macro-scale behavior by accounting for the micro-scale phenomena calls for microstructure-informed continuum models accounting properly for the deformation mechanisms identifiable at the micro-scale. Classical continuum theory, in contrast to the micromorphic continuum theory, is unable to take into account the effects of co...
Article
Full-text available
We show here that rotations of round particles in amorphous disk packing reveal various nontrivial microscopic features when the packing is close to rigidification. We analyze experimental measurements on disk packing subjected to simple shear deformation with various inter-particle friction coefficients and across a range of volume fractions where...
Article
This work is dedicated to the study of the effect of stress concentrations in plates induced by notches and holes using a Granular Micromechanics (GM) model. To this end, three structural configurations were analyzed: an intact plate, a plate with a central circular hole, and a plate with two notches. For comparison of the mechanical response of th...
Article
Although the primacy and utility of higher‐gradient theories are being increasingly accepted, values of second gradient elastic parameters are not widely available due to lack of generally applicable methodologies. In this paper, we present such values for a second‐gradient continuum. These values are obtained in the framework of finite deformation...
Article
Full-text available
The interfaces that biological tissues form with biomaterials are invariably defective and frequently the location where failure initiates. Characterizing the phenomena that lead to failure is confounded by several factors including heterogeneous material/tissue interfaces. To seamlessly analyze across these diverse structures presents a wealth of...
Article
In order to synthesize exotic metamaterials, it was proposed to use as elementary components of metamaterial microstructures so-called pantographic cells. The use of a mesomodel based on Euler–Bernoulli nonlinear beam theory is utilized for describing their behavior when their characteristic sizes are of the order of millimeters. With an in-house c...
Article
Granular-microstructured rods show strong dependence of grain-scale interactions in their mechanical behavior, and therefore, their proper description requires theories beyond the classical theory of continuum mechanics. Recently, the authors have derived a micromorphic continuum theory of degree n based upon the granular micromechanics approach (G...
Article
The mechanical performance of the dentin-adhesive interface contributes significantly to the failure of dental composite restorations. Rational material design can lead to enhanced mechanical performance, but this requires accurate characterization of the mechanical behavior at the dentin-adhesive interface. The mechanical performance of the interf...
Article
Resin-based composite has overtaken dental amalgam as the most popular material for the repair of lost or damaged tooth structure. In spite of the popularity, the average composite lifetime is about half that of amalgam restorations. The leading cause of composite-restoration failure is decay at the margin where the adhesive is applied. The adhesiv...
Article
Full-text available
Mechanical tests designed to measure classical behavior do not provide information underlying the macroscale response. Multiscalar digital image correlation (DIC) can be employed in these experiments to expose the micro-mechanisms that lead to the emergent macroscale behavior. This paper develops a multiscalar DIC methodology to study the extension...
Preprint
Full-text available
Microstructural dynamics in amorphous particle packings is commonly probed by quantifying particle displacements. While rigidity in particle packings emerges when displacement of particles are hindered, it is not obvious how the typically disordered displacement metrics connect to mechanical response. Particle rotations, in contrast, are much less...
Article
Mechanical behavior of materials with granular microstructures is confounded by unique features of their grain-scale mechano-morphology, such as the tension-compression asymmetry of grain interactions and irregular grain structure. Continuum models, necessary for the macro-scale description of these materials, must link to the grain-scale behavior...
Article
(Meta-) materials with granular microstructures exhibit nonlinear dispersive wave propagation, which is typically attributed to the presence of a microstructure. However, this behavior can arise from two additional sources in a linear non-dissipative system – the grain-scale or micromechanical characteristics and the grain-scale or micro-inertial c...
Article
Full-text available
Background: Since the mechanical behavior of pantographic metamaterials depends upon the properties of their microstructure, accurate descriptions of unit cells are needed. Objective: The present effort is motivated by this requirement to characterize the detailed deformation of unit cells formed of two orthogonal sets of 3 beams. Methods: Their de...
Article
The grain sizes can significantly influence the granular mechano-morphology, and consequently, the macro-scale mechanical response. From a purely geometric viewpoint, changing grain size will affect the volumetric number density of grain-pair interactions as well as the neighborhood geometry. In addition, changing grain size can influence initial s...
Article
Full-text available
The inherent degradation property of most dental resins in the mouth leads to the long-term release of degradation by-products at the adhesive/tooth interface. The by-products increase the virulence of cariogenic bacteria, provoking a degradative positive-feedback loop that leads to physicochemical and mechanical failure. Photoinduced free-radical...
Article
Full-text available
A possible strain energy density, incorporating Cosserat’s micro-rotations and Biot’s change in porosity conferred by the microstructure geometry, is proposed in an elastic, two-dimensional, nonlinear context. The nonlinearities are taken into account both extracting the exact macro-rotations by the polar decomposition of the standard deformation g...
Article
Full-text available
Granular micromechanics approach (GMA) provides a predictive theory for granular material behavior by connecting the grain-scale interactions to continuum models. Here, we have used GMA to predict the closed-form expressions for elastic constants of macroscale chiral granular metamaterial. It is shown that for macroscale chirality, the grain-pair i...
Conference Paper
The assessment of geomechanical properties of unconventional reservoirs is significant as they assist in placement as well as understanding of the geometry and properties of multi-stage hydraulic fractures in horizontal wells. Severe heterogeneities at micro-scale in addition to possibility of having non-intact samples provide opportunities for usi...
Chapter
In this work we present the results of an experimental parametric investigation of the mechanical behavior of the pantographic unit cells. The main goal is to determine extreme configurations of the geometric parameters of the microstructure. This work extends the set of measurements presented in a previous paper by analyzing a larger set of sample...
Article
This paper presents a 390-line code written in ANSYS Parametric Design Language (APDL) for topology optimization of structures with multi-constraints. It adopts the bi-directional evolutionary structural optimization method with the proposed dynamic evolution rate strategy (DER-BESO) to accelerate the iteration convergence. The complete APDL progra...
Article
Cosserat continuum model has attracted increasing interest for describing the mechanical behavior of microstructured solids. Existing formulation of Cosserat continuum model often overlooks chiral effects that arise from coupling between stretching deformations and the micro-rotation. Here, we introduce an extended Cosserat model that accounts for...
Chapter
In the online Stanford Encyclopedia of Philosophy1 one finds an accurate account of formal modern model theory, with a careful description of the underlying philosophical and mathematical arguments. Model theory was developed, in a more recent époque, by Alfred Tarski. It appears though that (see the Forgotten Revolution by Lucio Russo [1]) Helleni...
Article
Designing an acid fracturing model requires the coupling of two models numerically. The first one is the fracture propagation model, which is developed by the finite element method (FEM). The second model is the acid transport model, which is usually developed by the finite difference method (FDM). For complex geometries such as induced hydraulic f...
Article
Bacterial adhesion and growth at the composite/adhesive/tooth interface remain the primary cause of dental composite restoration failure. Early colonizers, including Streptococcus mutans, play a critical role in the formation of dental caries by creating an environment which reduces the adhesive’s integrity. Subsequently, other bacterial species, b...
Article
Objective: The purpose of this study was to evaluate a new synthesized multifunctional monomer, aminosilane functionalized methacrylate (ASMA), containing polymerizable methacrylate, tertiary amine, and methoxysilane functionalities in dental adhesive formulations, and to investigate the polymerization kinetics, leachates, thermal and mechanical p...
Article
In the literature of granular micromechanics it is standard to achieve, at the macro scale, non-standard enhanced continuum models [1-2]. Among a panoply of exotic behaviors, these models predict that granular materials can show chirality for a specific grain-pair interaction. To verify these predictions, a granular system with a specific grain-pai...
Technical Report
Full-text available
The anchorage behavior of headed bars at the end of beams within compression-compression-tension (CCT) nodes subjected to monotonic loading is assessed. The test parameters for the 10 specimens tested include the embedment length, number and spacing of the anchored bars, and the presence or absence of a head at the anchored end of the bar. The nomi...
Article
Full-text available
Nearly 100 million of the 170 million composite and amalgam restorations placed annually in the United States are replacements for failed restorations. The primary reason both composite and amalgam restorations fail is recurrent decay, for which composite restorations experience a 2.0–3.5‐fold increase compared to amalgam. Recurrent decay is a pern...
Article
In this study, deformation and failure mechanisms of mineralized tissue (bone) were investigated both experimentally and computationally by performing diametral compression tests on millimetric disk specimens and conducting finite element analysis in which a granular micromechanics-based nonlinear user-defined material model is implemented. The for...
Article
Full-text available
In this paper, we account for the research efforts that have been started, for some among us, already since 2003, and aimed to the design of a class of exotic architectured, optimized (meta) materials. At the first stage of these efforts, as it often happens, the research was based on the results of mathematical investigations. The problem to be so...
Article
Full-text available
In this paper, a strain gradient regularization of continuum damage mechanics is dealt with starting from a variational inequality. Full stress and strain analyses are reported for numerical tests performed with an in-house code based on the element free Galerkin method in two exemplary cases. Simulations show that the non-locality conferred to the...
Article
Full-text available
In the last decade, the exotic properties of pantographic metamaterials have been investigated and different mathematical models (both discrete or continuous) have been introduced. In a previous publication, a large part of the already existing literature about pantographic metamaterials has been presented. In this paper, we give some details about...
Article
The mechanics of axially moving media is significant because of their broad engineering applications. In many engineering applications, it is beneficial to understand the dynamical material response from a microstructural viewpoint. Here we focus upon wave propagation in axially moving materials with granular microstructure. To this end, the granul...
Article
In this paper, the granular micromechanics approach proposed by Misra and Poorsol-hjouy (2016) is used to study the dispersive behavior of granular materials in responseto elastic deformation waves. This study is motivated by the typical lack of connectionbetween the mathematical models, the parameters involved, and the physics of granularmaterials...
Article
Grain rotations are a key component of the grain-scale deformation kinematics of granular materials. For describing the deformation of these materials at large length scales, continuum description is efficient and desirable in spite of the current computational abilities. It is, however, clear that grain-scale deformation mechanisms have a profound...
Article
Pantographic metamaterials are known for their ability to have large deformation while remaining in the elastic regime. We have performed a set of experiments on 3D printed pantographic unit cells to parametrically investigate their response when undergoing tensile, compression, and shear loading with the aim of i) studying the role of each paramet...
Article
Full-text available
In this paper we reveal that the mathematical discrete model of Hencky-type, introduced in [1], is appropri- ate for describing the mechanical behavior of micro-metric pantographic elementary modules. This behavior does not differ remarkably from what has been observed for milli-metric modules, as we prove with suitably designed experiments. Theref...
Article
Full-text available
We formulate a discrete Lagrangian model for a set of interacting grains, which is purely elastic. The considered degrees of freedom for each grain include placement of barycenter and rotation. Further, we limit the study to the case of planar systems. A representative grain radius is introduced to express the deformation energy to be associated to...
Chapter
Synonyms Energy methods for granular materials; Varia-tional methods in granular micromechanics Definitions Granular mechanics is defined as the mechanics of materials with granular texture in which the role of grain interactions is paramount. The description of the mechanical behavior of these material systems begins from the conception of grain i...
Chapter
Synonyms Energy methods for granular materials; Variational methods in granular micromechanics Definitions Continuum models of granular materials aim to describe their behavior in average sense while exploiting the paradigm of continuum mechanics. For granular materials, however, success of these continuum models is predicated upon how they treat g...
Article
Full-text available
In order to get detailed information about the mechanical behavior of pantographic elementary substructure and elements, small-scale specimens were sintered using polyamide powder, constituted by three orthogonal pairs of beams interconnected through pivots forming pantographic cells. The mechanical properties of interconnecting pivots and constitu...
Article
Wave propagation in granular materials is known to be dispersive. Micromorphic continuum model based upon granular micromechanics (Misra, A. and P. Poorsolhjouy, Continuum Mech. Thermodyn, 2016. 28(1-2): p. 215-234.) has the ability to describe this dispersion behavior. In this paper we show that the dispersive behavior can be modulated by using el...
Article
Full-text available
Dentin adhesive systems for composite tooth restorations are composed of hydrophilic/hydrophobic monomers, solvents, and photoinitiators. The adhesives undergo phase separation and concomitant compositional change during their application in the wet oral environment; phase separation compromises the quality of the hybrid layer in the adhesive/denti...
Article
Resin-based composite has overtaken dental amalgam as the most popular material for direct restorative dentistry. In spite of this popularity the clinical lifetime of composite restorations is threatened by recurrent decay. Degradation of the adhesive leads to gaps at the composite/tooth interface-bacteria, bacterial by-products and fluids infiltra...
Article
Full-text available
Scanning acoustic microscopy (SAM) has been applied to measure the near-surface elastic properties of materials. For many substrates, the near-surface property is not constant but varies with depth. In this paper, we aim to interpret the SAM data from such substrates by modeling the interaction of the focused ultrasonic field with a substrate havin...
Article
Full-text available
The influence of loading upon the phonon dispersion of crystalline materials could be highly nonlinear with certain particular trends that depend upon the loading path. In this paper, we have calculated the influence of [100] uniaxial strain on the phonon dispersion and group velocities in fcc aluminum using second moments of position obtained from...
Article
Objectives: The objective of this study was to explore the effect of lysine integration to dental adhesives with respect to the polymerization kinetics, neutralization capacities in the acidic microenvironment, dynamic mechanical properties, and thermal properties. Materials and method: Lysine was incorporated into liquid resin formulations at 2...