RIT has a depth of experience in a variety of other established and emerging research areas, including astrophysics, microsystems, and modeling and simulation.
by: Josette Weinstein November 2012
Physics Professor Scott Franklin has been working with staples to find out why they stick together.
There are intriguing possibilities for using geometrically cohesive materials in construction, as they can form strong, lightweight structures. There may also be connections with biological organisms. For example, in order to survive flooding, fire ants group together and form rafts that look very similar to entangled piles of staples. As someone who has been working with granular materials such as sand and sugar, Franklin found himself working with geometrically cohesive materials, which are materials that resist getting pulled apart because of their geometry.
Each experiment had a pile of stapes all of the same length that were placed into a cylinder mold on top of a vibrating plate. The staples were then shaken and tested for how well they stayed together. As expected, the rigidity rose as the length of the staple arms increased; staples have more of a hook and therefore are more rigid than just rods.
Surprisingly, however, the rigidity peaked at a length of about 40% of the width and began to decrease again. Franklin believes that there is an optimum peak due to the fact that for the staples to stay together there needs to be a perfect balance of a hook and an opening space; as the hook increases, the opening space decreased and vice versa.
It was also found that the larger the pile, the easier it was to pull the staples apart. Franklin argues that this is most likely due to the "weakest link" theory which states that the whole structure is only as strong as its weakest link.
"With a larger pile, there is more of an opportunity for there to be a weak link," says Franklin.
Franklin is also working with RIT undergraduate students on a computer simulation that looks at what is going on inside the cylinder. His team is attempting to analyze the pressures affecting individual staple as they are being shaken. The work is providing new understanding of material bonding while also giving students real world research experience.
"It's really important that there are undergraduate students working on this project," Continues Franklin. "Because of how accessible this is to undergrads, is a big part as to why I got involved with researching granular materials."