Document Type

Honors Thesis


Mechanical Engineering Technology


Brett Ellis

Committee Members

Keith Berube, Vincent Caccese, Kathleen Elliss, Peter Howorth

Graduation Year

May 2021

Publication Date

Spring 5-2021


With approximately 5.9 million vehicular collisions in the United States per year, the ability of a vehicle to absorb energy during a collision is critical to reducing the likelihood and severity of injuries. A primary means to absorb energy during a collision is a crush tube, which is a predominantly-prismatic-shaped, metallic structure located at the front or rear of a vehicle intended to absorb energy by progressively buckling in addition to dissipating energy, crush tubes must be light weight to reduce vehicular green-house gas emissions, resilient to fatigue, resilient to environmental exposure, and economically feasible to manufacture. Historically, these competing objectives have been satisfied via extrusion, hydroforming, or a combination of extrusion and hydroforming manufacturing processes. Such manufacturing processes limit geometric freedom, resulting in a peak initial force significantly greater than the mean force during progressive buckling. Thus, the problem, i.e., crush tubes cause an excessively large initial deceleration due the current manufacturing process. This research seeks to address this problem via two actions:

  1. Explore fused depositional modeling (FDM) as a possible manufacturing process for energy dissipating structures.
  2. Characterize the effects of FDM processing parameters and honeycomb meso-structures on energy dissipation properties (e.g., peak initial for, mean force, total energy dissipated, slope of force-deflection curve during progressive buckling). Honeycomb structures will be subjected to quasi-static, compressive forces within a design of experiments (DOE) framework.
The results of this thesis can be used to influence the design of crush tubes and energy dissipative structures made of materials that are more conductive to automotive components such as aluminum or steel. The results can also be used to categorize the physical properties of Polylactic Acid 3D printed components.