Our research deals with elongated particles (rods) and how they jam in hoppers depending upon the particle aspect ratio (length divided by width), material properties (i.e. coefficient of friction), and the dimensions of the system. The first critical question we will address is how the mean number of particles that exit the hopper diverges as we approach a critical aperture size. The data that has been collected will be used to determine whether a critical point exists for elongated particles like that of round particles. The number of particles n that exit a hopper before the system jams follows a probability distribution P(n) that decreases exponentially with n and scales with the average number to exit, {n}, like with spherical particles. Does this divergence ever reach a point where the system cannot jam? Research of the jamming of elongated particles in a hopper can lead to the answer of these questions and new understandings of granular material in a hopper flow that would be significant to both the scientific and industrial communities.

The equipment for this project is currently being updated. Our hopper has two walls, each of which can be tilted independently to any angle. One wall slides so that the opening of the aperture is anywhere from 2 cm to 38 cm wide in the x and y plane. The length, in z direction, of the hopper’s aperture can be varied from several article diameters to 33 cm by inserting a piece of Plexiglas.

Previously the experiment was run by hand, the data was then taken and recorded by hand. Therefore, I am currently working on automating the procedure so that I will be able to focus upon the analysis and results rather than simply collecting and recording the data.

Because statistical data analysis requires many, many experimental runs, the experiment will then be repeated ad nauseam. The experiment will independently vary the particle aspect ratio, the properties of the particle material, and the size and dimensions of the system. These variables will then be analyzed to determine what correlates to the amount of particles that exit the hopper before a jam is formed. Other variables to be considered are the changes caused by varying the amplitude of the vibrating feeder as well as the effects of the varying how hard or soft the hammer taps the hopper to reestablish particle flow.