My graduate training is in progressive collapse of steel framed structures. The objective was to understand the flow of deformation energy during the collapse. One could visualise the energy as water flowing in the pipes. Once the energy overflows, the pipe bursts. The study provided understanding on the propagation of strut/column buckling waves. Also, it highlighted the minimization of the kinetic energy, or the deformation energy is suitable objective functions for structural optimisation against disproportionate collapse.
Our background is also in the stability of thin-walled structures. We developed an analytical formulation for prediction of ultimate buckling strength of sandwich panels. Although the work was focused on cellular metallic cores, the equations and the methodology apply to the majority of the sandwich panels with metallic face sheets. The work was carried out with prof. Benjamin Schafer (the Johns Hopkins University), Prof. Jerome Hajjar (Northwestern University in Boston) and prof. Sanjay Arwade at the University of Massachusetts in Amherst.
Medical imaging was employed to quantify failure mechanisms and deformations preceding the collapse, debonding and fracture. The objective of this research was to develop a computational material model that accounts for the inherent material variability and predicts failure under multi-axial loads. This work is part of a larger effort to help develop steel foam as a material with relevance to civil engineering applications in collaboration with the University of Massachusetts at Amherst, the Johns Hopkins University, Northeastern University, University of Southampton and Fraunhofer Institute in Germany.
We have developed scripts for the generation of correlated random variables to include spatial variation in the material properties. Especially metallic foams exhibit noticeable variation in pore geometries, wall thickness and micro-porosity. While these variations are not critical under compressive loads, they affect the reliability of the components subject to tensile, shear, or torsional loads.