Soroosh Hassanpour

Micropolar elasticity theory: a survey of linear isotropic equations, representative notations, and experimental investigations:

This paper is devoted to a review of the linear isotropic theory of micropolar elasticity and its development with a focus on the notation used to represent the micropolar elastic moduli and the experimental efforts taken to measure them. Notation, not only the selected symbols but also the approaches used for denoting the material elastic constants involved in the model, can play an important role in the micropolar elasticity theory especially in the context of investigating its relationship with the couple-stress and classical elasticity theories. Two categories of notation, one with coupled classical and micropolar elastic moduli and one with decoupled classical and micropolar elastic moduli, are examined and the consequences of each are addressed. The misleading nature of the former category is also discussed. Experimental investigations on the micropolar elasticity and material constants are also reviewed where one can note the questionable nature and limitations of the experimental results reported on the micropolar elasticity theory.

Dynamics of 3D Micropolar Gyroelastic Beams

This paper is devoted to the dynamic modeling of micropolar gyroelastic beams and explores some of the modeling and analysis issues related to them. The simplified micropolar beam torsion and bending theories are used to derive the governing dynamic equations of micropolar gyroelastic beams from Hamilton’s principle. Then these equations are solved numerically by utilizing the finite element method and are used to study the spectral and modal behaviour of micropolar gyroelastic beams.Copyright

Step-by-Step Simplification of the Micropolar Elasticity Theory to the Couple-Stress and Classical Elasticity Theories

The micropolar elasticity theory provides a useful material model for dealing with fibrous, coarse granular, and large molecule materials. Though being a well-known and well-developed elasticity model, the linear theory of micropolar elasticity is not without controversy. Specially simplification of the microppolar elasticity theory to the couple-stress and classical elasticity theories and the required conditions on the material elastic constants for this simplification have not been discussed consistently. In this paper the linear theory of micropolar elasticity is reviewed first. Then the correct approach for a consistent and step-by-step simplification of the micropolar elasticity model with six elastic constants to the couple-stress elasticity model with four elastic constants and the classical elasticity model with two elastic constants is presented. It is shown that the classical elasticity is a special case of the couple-stress theory which itself is a special case of the micropolar elasticity theory.Copyright

Dynamics of a 3D Micropolar Beam Model

The development of a simplified micropolar beam model is presented and the governing dynamic equations for a micropolar beam deforming in 3D space, under different types of external loading and boundary conditions are derived. The dynamic equations are derived from Hamilton’s principle and the finite element method is used to provide numerical examples. The modal behavior of the developed micropolar beam model and the conditions under which the results of classical beam models will be recovered are presented.Copyright

Spectral and Modal Behaviour of 3D Timoshenko Gyroelastic Beams

Gyricity is a continuous distribution of embedded angular momentum that is considered intrinsic to the constitutive material of the structure. Gyroelastic beams, a special case of general gyroelastic systems, are analyzed in this paper where the governing equations for a gyrobeam are formulated by employing the simple longitudinal deformation theory, Duleau torsion theory, and Timoshenko bending theory to model the beam elasticity. The obtained gyrobeam model is used to study the spectral and modal behaviour of thick gyroelastic beams.Copyright

Spectral and Modal Behaviour of 3D Euler-Bernoulli Gyroelastic Beams

A material with a continuous distribution of embedded angular momentum, called gyricity, was first proposed with a view to modelling structures that have numerous discrete gyroscopic elements. Gyroelastic beams, a special case of general gyroelastic systems, are analyzed in this paper where the governing equations for a slender gyrobeam are formulated first and then these equations are used to study the spectral and modal behaviour of gyroelastic beams.© 2014 ASME

A control-oriented modular one-dimensional model for wall-flow diesel particulate filters:

A comprehensive modular one-dimensional physics-based mathematical model is developed for non-isothermal compressible flow, pressure drop, and filtration and regeneration processes in wall-flow diesel particulate filters. Employing a modified orthogonal collocation method and symbolic computation in Maple™, the governing partial differential equations are reduced to a control-oriented model governed by ordinary differential equations which can be solved in real time. Numerical examples are provided to indicate the accuracy and computational efficiency of the developed model and to study the different behaviors of wall-flow diesel particulate filters.

Approximation of Infinitesimal Rotations in Calculus of Variations

This paper focuses on problems dealing with very small angular displacements, i.e., infinitesimal or micro rotations, where these rotations are desired to be approximately treated as Euclidean vectors. For such problems, an appropriate and consistent approach to approximate the rotation matrix, the angular velocity and acceleration vectors, and the virtual rotation vector, up to the first order, is presented and the calculus of variations (or Hamilton’s principle) when applied to such problems is characterized. Also, a discrepancy observed in previous works dealing with the infinitesimal rotations, where second- or higher-order approximations have been employed, is reviewed. The consistent and comprehensive approach for the first-order approximation of infinitesimal rotations, presented in this paper, is employed to derive the dynamic equations of a symmetric spinning top and a gyroelastic continuum and is proved to result in the correct and complete dynamic equations.

An Optimization-Based Algorithm for Determination of Inclusive and Constant Orientation Workspace of Parallel Mechanisms

Workspace of a mechanism is generally defined as the region of space which end-effector of that mechanism can reach. Determination of workspace is an important task in the design of a mechanism. However, for parallel mechanisms, due to the complexity of solving the forward kinematic equations, determination of workspace is much more complicated than for serial mechanisms. In the literature, time-consuming numerical methods, such as point-by-point searching, are usually employed for this purpose. In this paper, an optimization-based algorithm is introduced for the boundary determination of inclusive and constant orientation workspaces of parallel mechanisms. In the proposed algorithm, thanks to applying the optimization approach along with point-by-point searching, the dimension of the point-by-point searched space (and hence, the consumed time) are significantly reduced. While different optimization methods can be used in the proposed algorithm, Particle Swarm Optimization is utilized as the optimization technique in this paper. The proposed algorithm is illustrated through its application to a planar and a spatial parallel mechanism.Copyright