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EAS Doctoral Proposal Defense by Soolmaz Khoshkalam

When: Wednesday, December 13, 2023
9:30 AM - 11:30 AM
Where: > See description for location
Description: EAS Doctoral Proposal Defense by Soolmaz Khoshkalam

Date: Wednesday December 13, 2023

Time: 9:30am

Topic: A Dynamic Formulation for Potential of Mean Force-Based Lattice Element

Location: CSCDR TXT 105

The potential-of-mean-force (PMF) approach to the lattice element method (LEM) has recently been developed and utilized for simulating the fracture in heterogeneous materials and adapted to model the response of structural systems. LEM is a quasi-static approach which relies on lattice discretization of the domain via a set of particles that interact through prescribed potential functions, representing the mechanical properties of members. The approach offers unique advantages, including robustness to discontinuity and failure without the need for mesh refinement, and the ability to accurately simulate nonlinearities through the use of non-harmonic potentials. The overall goal of this research is to extend the PMF-based LEM for simulation of dynamic response. Such simulation framework provides a means for simulating nonlinear response and failure under dynamic loading that is the nature of most natural hazards and extreme conditions. Furthermore, a dynamic LEM approach opens the door for consideration of dynamic fracture and wave propagation in heterogeneous media.
For our analysis we leverage the advances in Molecular Dynamics (MD) integration methods for estimation of the trajectory of particles in the Lattice Element Method (LEM) and to simulate the dynamic response with a focus on structural (or building) systems. To this end we use Verlet-Velocity method for time integration, to estimate the location and momentum of each particle at every time step. To address the limitations of the explicit integration methods regarding small time-increments and to assure accuracy and the numerical stability, we also plan to explore implicit integration techniques such as Hilber-Hughes-Taylor method and midpoint method.

Noting that the rotational degrees of freedom have minimal contribution to the kinetic energy of the system we develop an energy-based approach for static condensation to reduce the computational cost. Our approach relies on the Euler-Lagrange equation which manifests in the form of minimum potential energy theorem for mass-less degrees of freedom.
Finally, shifting attention to another critical aspect of dynamic simulation the mass matrix, we adopt an energy-based approach and utilize the kinetic energy of the lattice elements to maintain consistency with the kinetic energy of their continuous bar counterpart.

Dr. Mazdak Tootkaboni, Dept of Civil and Environmental Engineering (Advisor (
Dr. Arghavan Louhghalam, Dept. of Civil and Environmental Engineering (Co Advisor)(

Dr. Alfa Heryudono, Department of Mathematics
Dr. Zheng Chen, Department of Mathematics

All EAS Students are ENCOURAGED to attend.
Contact: Engineering and Applied Sciences
Topical Areas: Faculty, Students, Students, Graduate, Students, Undergraduate, Mathematics, Bioengineering, Civil and Environmental Engineering, College of Engineering, Computer and Information Science, Co-op Program, Electrical and Computer Engineering, Mechanical Engineering, Physics