2024 ASEE Annual Conference & Exposition

Blast loads on structures are exciting! They are big and surprising and set structures in motion. They also pique student interest in the details of transient loading, structural dynamics, and dynamic amplification of loads. Small-scale model demonstrations in structural dynamics courses are very common, with well-defined structures, subjected to free and forced vibration experiments, providing a physical representation of larger framed structures. As a course moves from well-described forcings and closed-form solutions to numerical time-stepping methods there is an opportunity with blast loads to introduce numerical methods in a highly contextualized and engaging way.
If you hand a student an air cannon and ask them to shoot you in the face, they will happily oblige. If you ask them to fire the air cannon at a small structure and characterize the blast load based on the measured response of the structure, they will ask you for a little help. They need to know the dynamic parameters of the structure, like stiffness, mass, and damping. They need to be able to measure response, and their mobile phone turns out to be a very good tool for this. Finally, they need a way to solve for the dynamic response of the structure based on an arbitrary blast loading and you happen to have introduced a spreadsheet implementation of Newmark’s method. All the pieces are in place; let’s see what the students do!
This paper describes the implementation and results of a blast loading experiment using air cannons and the resulting student responses. Exam performance was comparable to students in a previous offering without the laboratory. Laboratory reports provided insight consistent with prior studies of problem-based learning and that support theories that experimentation labs may be more effective than verification labs.