Engineering Commons^™

Transient Nonlinear Vibration Characterization Of Building Materials In Sequential Impact Scale Experiments, James Bittner, John S. Popovics

Michigan Tech Publications

Characterizing standard building materials such as concrete is challenging primarily because of the broad range of constituent component sizes within the material itself. Concrete, the most ubiquitous building material, contains critical components that span at least three orders of magnitude of physical size. This work introduces a nondestructive sequential impact test to extract transient nonlinear vibration behaviors that provide statistically significant holistic characterization of a heterogeneous building material, neat cement paste, on a centimeter scale sample. The sensitivity of the single impact vibration combined with the repeatability of the new sequential apparatus enables the extraction of statistically distinct transient nonlinear …

Experimental Investigations Of Yarn Pull-Out Behavior In Kevlar®: Influence Of Applied Metallic Coatings And Effect Of Dynamic Loading, Julie Ann Roark

Theses and Dissertations

Flexible woven Kevlar® textile fabrics are widely used in protective armor applications. Yarn pull-out, comprised of yarn uncrimping (i.e., straightening) and yarn translation, is a major energy absorption mechanism during ballistic impact onto these fabrics, especially for impact velocities below the ballistic limit. Yarn pull-out is influenced by various parameters including inter-yarn friction, pull-out distance, pull-out velocity, transverse pre-tension, fiber diameter, fabric architecture, fabric waviness, fabric count and yarn modulus.

The first part of this thesis investigates yarn pull-out behavior of commercially available Kevlar® KM2+ individual yarns coated with metallic layers (copper, aluminum, aluminum nitride, silver) via a directed vapor …

The Development And Analysis Of Methods Used To Evaluate American Football Facemasks, Alexander Bina

All Dissertations

The motivation for this Ph.D. dissertation is to provide football equipment managers, coaches, parents, athletes, and relevant industry personnel with an understanding of the implication a chosen football facemask design will have on the safety of the athlete. As athletes have increased their capacity for speed, size, and strength, so too has the head injury risk increased in American football. To align with the increase in head impact injury in American football, the protective head impact community must expand its capacity to evaluate protective equipment systems. This dissertation focuses specifically on one helmet system component: the football facemask. This dissertation …

Comparison Of Three-Dimensional Dynamic Models For Golf Clubhead-Ball Impacts, Adam Caldwell, John Mcphee

International Sports Engineering Association – Engineering of Sport

No abstract provided.