Mark Rashid

Portrait of Mark Rashid

Position Title
Chair, Admissions and Enrollment


Professor Rashid’s research activities fall into the broad disciplines of solid mechanics and computational methods.  Current focus areas include:

  • Fracture mechanics modeling.  The Exclusion Region theory  of fracture, first published in 1997 by Prof. Rashid, constitutes a general theoretical framework for surface separation – i.e. fracture – in solid continua.   Unlike classical approaches to fracture, the ER theory places no restrictions  on the nature of the bulk constitutive behavior, nor on the crack trajectory.   The ER theory is essentially a broadened constitutive formalism that  applies in the near-tip region, and which admits the kinematics of  surface  separation.  In the ER theory, the fracture behavior itself, as distinct  from the bulk material response, is the subject of a separate constitutive  specification, in the form of a “separation function.”  Recent activities  include calibration of the separation function for a number of ductile metals,  and computational studies of  non-self-similar ductile crack growth near functionally graded interfaces in elastic-plastic materials.
  • Computational fracture mechanics.  To support the technological application of the ER theory, a nonlinear, quasistatic, finite-element-based computational capability has been synthesized.  The code, called FEFRAC, has matured into a robust and flexible analysis tool for elastic-plastic fracture mechanics studies.  The code contains a number of  innovative features, including a “moving mesh patch” construct which allows for arbitrary (and       a priori unknown) crack paths, and a highly effective iterative  scheme which simultaneously enforces both equilibrium and the separation criterion.
  • The Variable-Element-Topology Finite Element Method (VETFEM).  The  VETFEM is a general-purpose finite element method in which each element is  free to take essentially any polygonal (polyhedral in 3D) shape.  The  VETFEM retains all of the powerful features of the conventional FEM, while  exhibiting the additional advantage that automatic mesh generation is enormously  simplified.
  • Blast loading / fluid-structure interaction.  Current work  involves use of a novel incompatible-embedded-mesh method in which inter-mesh  compatibility is enforced in a variationally consistent manner.  This  allows the fluid and solid meshes to be constructed independently of each  other, thereby greatly reducing the burden associated with carrying out the  analysis.
  • MEMS devices.  Of particular interest are nonlinear thermomechanical  and electromechanical phenomena, such as buckling and snap-through.  In  collaborative work with Professor Rosemary Smith (Univ. of Maine Electrical  Engineering), a bistable device has been analyzed in which buckling is used  to provide an irreversible indication of a specified temperature excursion.