All are welcome to attend a research seminar presented by engineering faculty candidate Dr. Hector Medina on Thursday, May 29, from 1:30 to 2:30 p.m. in EHS 125.
Dr. Medina’s seminar will address two subjects – one related to missionary work of installing Christian radio studios around the world (25 percent of time allocated) and the other to his research, “Where do Random Rough Surfaces Fail?” (25 percent of time allocated)
Following is an abstract to the research talk:
“Roughness is ubiquitous and it is introduced on material surfaces either by spontaneous degradation, manufacturing processes, or intentionally for engineering purposes. However, under certain loading conditions, surface’s topography coupled with material’s degree of brittleness can significantly compromise the efficiency of energy production, the safety and reliability of components, and ultimately increase of costs. To the engineer, a relevant task is to be able to predict the mechanical impacts of such degradation as early as possible.
The complexity of a random configuration renders difficult the problem of analytically finding relationships between surface parameters and markers indicative of mechanical failure. Another difficulty is the reproducibility of replicates of specimens possessing random rough surfaces, for destructive testing followed by statistical analysis.
An experimental technique to produce highly controlled replicates of random rough surfaces (including modeling of degradation growth) was developed and used to experimentally and statistically solved the aforementioned problem. An empirical relationship was derived between stress concentration factor and the root-mean-square roughness (RMS) and auto correlation length (ACL) of a slightly roughened surface.
In order to strengthen our results, an analytical solution was sought by setting up and solving a boundary-value problem involving traction-free random rough surfaces, using a perturbation method, assuming elastic and isotropic conditions. The exact analytical solution was found which agrees very well with experimental and Finite Element Analysis results.”