Research philosophy, approach, and directions

My research directions and philosophy has evolved during past years. In 1985, when I was a senior student at Sharif University of Technology, I took courses on “Matrix Structural Analysis”, “Structural Dynamics”, and “Bridge Engineering”, I got interested in seismic or dynamic structural design of bridges and became a design/project engineer, so I selected my BSc project on: “Matrix Structural Dynamics, Analysis & Design of Highway Bridges of four types: Steel Truss Bridge, Steel Orthotropic Deck Bridge, Composite R/C-Steel Deck Bridge&  R/C Deck Bridge”

In 1986, as soon as I took a course on FEM at the beginning of my MSc curriculum at Sharif University of Technology, I decided to start my MSc thesis on Computational Structural Dynamics. My academic Master and Sheikh became Prof. Klaus J. Bathe. Then, I got interested in Finite Element Methods, specifically, nonlinear solid and structural mechanics and dynamics problems. I selected my MSc thesis to conduct research on: “Nonlinear Geometric & Material Finite Element Stress Analysis”. In 1990, I wrote my first conference paper, entitled: “An Assessment of Solution Algorithms of Nonlinear Equations Due to FEM Discretization in Nonlinear Structural Mechanics with Emphasis on BFGS”.

During my military service, from 1990 to 1992, I served as a lecturer in the department of aircraft engineering at the University of Aeronautical Engineering. So I got interested in matrix design/ analysis of aircraft structures. This became my eagerness to follow my PhD in aerospace structures.

During my stay in the department of Aerospace and Mechanical Engineering at The University of Arizona, from 1993 to 1994, my research focus turned toward multi-body dynamics and computer-aided analysis of mechanical systems, as proposed to me by Prof. P.E. Nikravesh.

After that, during my PhD at Sharif University of Technology, from 1994 to 1999, I got interested in Earthquake Engineering, specifically, “Nonlinear Dynamics and Adaptive Control of Structures”. So this field became my principal research theme in my remaining academic life. This, in addition to closely-related research subjects of Smart Structures and Materials (SSM), Structural Health Monitoring (SHM), Composite Structurs & Materials (CSM),Finite Element Model-Updating, Passive Control of Viscoelastic Structures, and Stochastic Structural Dynamics were the major theme during my research as full-time assistant professor in the departments of civil engineering, from 2000 to 2007.

From 2008 until present that I have changed my affiliation to the department of mechanical engineering, I have continued those previous topics, but with a taste of more mechanical and aerospace structures than civil and off-shore structures. These mechanically-oriented research themes are, from the oldest to the latest, Fluid-Structure Interaction (FSI), Eenergy Harvesting Systems (EHS),MEMS/NEMS, nonlinear structural mechanics, random fields and excitations, mechatronics, vibro-acoustics, opto-mechatronics, biomechanics, and the latest are bio-mechatronics.

In brief, I may divide my principal fields chronogically based on the following table:

As a matter of fact, my research has turned direction from more theoretical and computational mechanics research toward more mechatronics-oriented product design and manufacture. At present, I and my graduate students team are working on the product-based projects of Adaptive Focus Liquid-Lens Eyeglasses and Liquid Crystal Contact Lens, Wire-less Lead-less Cardiac Pacemakers, Artificial Mitral Valves by SMA, and the like.

Research activities (By chronological order)

My research directions and philosophy have evolved during past years. I may partition my viewpoint into eight time intervals, based on a chronological order of my growth in academic life.

a) BSc curriculum at SUT (1979-1986):

In this period, I was immature and less educated in doing research. In 1985, during my senior undergraduate at Sharif University of Technology, I focused on design projects. My BSc design project was Matrix Structural Dynamics, Analysis and Design of Highway Bridge Structures of four types: (1) trussed, (2) orthotropic steel deck, (3) R/C deck, (4) composite steel/concrete deck bridges. In this period of my academic life, my research viewpoint is more design-oriented than analytical.

b) MSc curriculum at SUT (1986-1990):

In 1986, as soon as I took a course on FEM at the beginning of my MSc curriculum at Sharif University of Technology, and I got familiarized by the 1982 edition of “Finite Element Procedures in Engineering Analysis” textbook of Prof. Klaus J. Bathe, he became my academic Master and Sheikh. I found my interest on the topic of Computational Structural Dynamics by FEM, starting my MSc on computational structural mechanics, specifically, on nonlinear solid/ structural mechanics problems. I selected my MSc thesis to conduct research on: “Nonlinear Geometric and Material Finite Element Stress Analysis of Continua by BFGS Algorithm”. In 1990, I wrote my first paper, entitled: “An Assessment of Solution Algorithms of Nonlinear Equations Due to FEM Discretization in Nonlinear Structural Mechanics with Emphasis on BFGS”. During this period, I did some unpublished research on the structural design of composite RPV. In this period of my academic life, my research viewpoint is more computational/analytical-oriented than design. The textbook of “Finite Element Procedures in Engineering Analysis” by Prof. K.J. Bathe became a launcher for throwing me inside computational structural dynamics field and even further, this text showed me that there is no difference among different physical systems and their fundamental physics principles, whenever these systems are modeled by mathematical analysis, specifically by calculus, differential and integral equations (ODEs, PDEs, Green’s functions, variational calculus), and finite/infinite dimensional vector spaces; finite for lumped-parameter and infinite for distributed-parameter modeling. This finding started my interests in system dynamics field (as well as feedback control) circumventing structural dynamics. This drove me toward active structural control during my PhD program.

Partial abstract of my MSc thesis (1990)

In this thesis, I developed nonlinear finite element algorithms for 2D plane stress, plane strain, and axisymmetric solids and continua subjected to large rotations, large deformations, and large strains like the extrusion and forging metal forming manufacturing processes. The problem formulation is highly nonlinear from geometry, material, and boundary conditions viewpoint. The analysis needs automatic re-mesh generation for avoiding non-convex finite elements to be generated. The solution procedure is based on two nested iteration loops, the outer loop for incremental load steps, and the inner loop for convergence between external incremental loads and generated internal incremental stress states in any discrete point of the structure. Transforming nonlinear PDEs of time-dependent and space-dependent to either nonlinear ODEs (time-dependent dynamic problems) or nonlinear algebraic equations (static problems) by finite element discretization properties establishes a system of highly nonlinear equations to be solved. In the case of nonlinear ODEs the discretization process continues with Newmark’s β method. In any case, these nonlinear algebraic equations are solved by BFGS algorithm which is inherently an optimization solver. In the nonlinear continuum mechanics formulation, I have used Green-Lagrange strain tensor measures and 2nd Piola-Kirschhoff stress tensor. For coding my algorithms, I have used FORTRAN 77.   

c) Military Service at University of Aeronautical Engineering (1990-1992):

During my military service, from 1990 to 1992, I served as a lecturer in the department of aircraft engineering at University of Aeronautical Engineering of Iranian Air Force Army. So I got interested in matrix structural dynamics/design/analysis of aircraft structures. This triggered my decision to follow my PhD in aerospace structures. In the military service period, I switched from large-scale civil structures toward large-scale aerospace structures.

d) PhD curriculum at University of Arizona (1993-1994):

During my stay in the department of AME at The University of Arizona, from 1993 to 1994, my research focus turned direction toward multi-body dynamics and computer-aided analysis of mechanical systems, as proposed to me by Prof. P.E. Nikravesh.

e) PhD curriculum at SUT (1994-1999):

After that, during my PhD at Sharif University of Technology, from 1994 to 1999, I was interested in EarthquakeEengineering and Nonlinear StructuralDdynamics and Adaptive Control of Structures. I conducted research on model-reference adaptive control (MRAC), semi-active switching control, model predictive control (MPC), robust control, and stochastic system parameter and state variable estimation algorithms, specifically filtered-x LMS and extended Kalman optimal filtering algorithms. I wrote my codes by MATLAB and Simulink. These research subjects, crystallized in the “Smart Structures & Materials”, become my principal research theme in my remaining academic life.  

Partial abstract of my PhD thesis ((1999)

In this thesis, I developed and implemented several nonlinear structural feedback and feedforward nonlinear controller/observer algorithms, specifically for finite element discretized continuous framed structures subjected to nonstationary non-Gaussian input signals as well as seismic records of strong motion. Nonlinearity for structures is a type of time-varying boundary conditions and of control algorithm is due to off/on commands and/or time varying static (stiffness) and dynamic (damping) properties of the structures. In addition, the adaptive type of control strategies has benefitted from a stochastic parameter and state estimation approach. Stochastic extended Kalman filtering has been implemented for estimating state variable signals (acceleration, velocity, and displacement), while filtered-x LMS has been used for estimating the system properties (stiffness and damping properties). Three important control strategies I have developed are: (1) model-reference adaptive control (MRAS), with two loops one inner loop for turning back the feedback state variable signals for comparison with reference model and the outer loop, a parameter identification/estimation algorithm for estimating time-dependent parameter variables, (2) model predictive control (MPC), with a horizon for extrapolation of state variable signals resulting from updated model and (3) robust control, with structured uncertainty blocks (by knowing a priori, either a specific probability distribution/density function of inputs or their auto-correlation/ cross-correlation functions) resulting from Bayes’ theorem and statistics (past information). My codes is developed in the environment of MATLAB, its toolboxes, and Simulink.

f) Assistant Professor of Civil Engineering at IUT (2000-2003):

I did research on “finite element dynamic model updating by frequency response function Matrices and system output error model”, “dynamics/passive controls of seismically-excited viscoelastic structures of tall buildings”, and “stochastic dynamics finite element model updating by Bayesian theorem and random vibration techniques”.

g) Assistant Professor of Engineering Math at UI (2003-2008):

The theme of “Smart Structures & Materials”, in addition to closely-related research subjects of structural health monitoring (SHM), piezoelectric smart structures, finite element model-updating, passive control of viscoelastic structures, and stochastic structural dynamics were my major research themes.

h) Assistant Professor of Mechanical Engineering at IUT (2009-2013):

During my return to Isfahan University of Technology but this time, the department of mechanical engineering, my research directions turned towards mechanical engineering applications of structural dynamics and smart structures and got more interdisciplinary. I conducted research on dynamic system identification of structures, structural health monitoring (SHM) and structural damage identification, NEMS and scale-dependent elasticity and continuum mechanics.

i) Associate Professor of Mechanical Engineering at IUT (2013-2020):

From 2008 until present that I have changed my affiliation to the the department of mechanical engineering, I have continued those research topics in my stay in the departments of civil engineering, but with a taste of more mechanical structures and applied mechanics than civil structural mechanics and engineering. These mechanical-oriented research themes are, from the oldest to the latest, fluid-structure interaction (FSI), MEMS/NEMS, nonlinear structural dynamics, random fields/vibrations, composite plate and shell nonlinear vibrations, energy harvesting systems (EHS), mechatronics, vibro-acoustics, opto-mechatronics, and the latest are bio-mechatronics.

As a matter of fact, recently, my research has turned direction from more theoretical and computational mechatronics research toward more innovative designs and mechatronics-oriented product design and industry 4.0-based manufacturing. At present, I and my graduate student teams are working on the subjects of adaptive-focus liquid-lens eyeglasses, wire-less lead-less cardiac pacemakers, artificial mitral valves by SMA, and continues.

Research plans for the next coming years

Based on present conditions of our world, I am predicting that my research plans may be divided along the following fundamental directions:

1. Structural Dynamics/Mathematical Analysis, i.e., multi-physics system modeling, analytical (physics-based), numerical (computer-based), and experimental (data-based) formulation, Monte Carlo simulations, and deterministic/stochastic solutions, validation/verification, structural/system identification/finite element model updating, and data interpretation/discussion, and parametric/case studies.
2. Machine Learning-based Dynamic Systems Synthesis, Analysis & Design, 3D Print-aided Manufacturing.

Engineering/Mathematical Analysis phase is divided among the following areas:

1. The most favorite direction, under the influence of my PhD curriculum, should be Smart structures and materials, Adaptive structures, Intelligent structures, Active structures, Electronic structures, Piezoelectric structures and materials, Structronics, Mechatronics, and so on. The specific topic shows the level and grade of intelligence and adaptivity. I am also working in the subfields of Structronics, i.e., Structural health monitoring (SHM), Structural system identification (SSI), Structural damage detection, Energy harvesting systems (EHS), and so on. In fact, this branch of engineering knowledge brings together the subdomains of (1) Dynamics (structural dynamics and vibrations), (2) Electronics and Controls (actuator and sensor technology), and (3) Computer Science (AI and machine learning).
2. I have been changing my research direction continuously toward a greater circle, i.e., Smart systems and intelligent machines, including multi-physics systems of mechanical, electrical, magnetic, thermal, optical, hydraulic, pneumatic, chemical, and biological phenomena and characteristics, and multi-physics modeling by analytical/ theoretical, computational/ numerical, and experimental/ laboratory methods. Up to this date, I have touched the interdisciplinary fields like, bio-mechatronics, opto-mechatronics, fluid-structure interaction (FSI), MOEMS and NOEMS.
3. The third line of my research, as before, would have more attention towards data-driven modeling of multi-physics dynamic systems, using AI, machine learning, machine vision, and upgrading those dynamic models with mathematical and fundamental physics-driven modeling of dynamic systems.
4. I am going to conduct research on soft robotics with my previous knowledge on structural and system dynamics, adaptive control, robust control, and multi-body dynamics.
5. I am going to establish effective teams of younger faculty members/postdocs and graduate/ undergraduate students to convert and promote the conceptual and brainstormed mechatronic designs to manufactured rapid prototypes and pilot products. For this target, I need grants from industry, government, and academia. In addition, I am insisting on organizing an equipped Industry 4.0 AI-motivated laboratory for completing a mechatronics project from zero to one hundred.

Added value of my activities to the prospective department, campus, and university

If I would join any department, I would be one gear (one single faculty member) of a huge gearbox (the campus). Therefore, I could be of value based on the above-mentioned research directions, if the whole system (campus) could move forward, translate, and rotate intelligently and efficiently. I, as a single gear, try my best to move forward this gearbox as much as I can.