IMPACT RESISTANT GLASSY POLYMERS: PRE-STRESS AND MODE II FRACTURE FEBRUARY 2013 JARED STEVEN ARCHER B.S., WESTERN WASHINGTON UNIVERSITY M.S., UNIVERSITY OF MASSACHUSETTS AMHERST Ph.D., UNIVERSITY OF MASSACHUSETTS AMHERST Directed by: Professor Alan J. Lesser Model glassy polymers, polymethyl methacrylate (PMMA) and polycarbonate (PC) are used to experimentally probe several aspects of polymer f...

We measure the quasistatic friction force acting on intruders moving downwards into a granular medium. By utilizing different intruder geometries, we demonstrate that the force acts locally normal to the intruder surface. By altering the hydrostatic loading of grain contacts by a sub-fluidizing airflow through the bed, we demonstrate that the relevant frictional contacts are loaded by gravity r...

We have evaluated the energy loss of swift hydrogen ions moving through a solid target, paying special attention to the effect due to the polarization of the projectile. Our calculation is done in the framework of the dielectric formalism, taking into account the contribution to the energy loss due to the charge fraction of protons and hydrogen atoms, the electronic capture and loss processes, ...

Embolization by a dislodged projectile is a rare complication that may occur in cases of gunshot cardiac injuries. We report a case of a firearm projectile cardiac injury that evolved, with dislocation of the projectile during cardiac surgery, into embolization of the right external carotid artery.

Launch uncertainties in uncontrolled direct fire projectiles can lead to significant impact point dispersion, even at relatively short range. A model predictive control scheme for direct fire projectiles is investigated to reduce impact point dispersion. The control law depends on projectile linear theory to create an approximate linear model of the projectile and quickly predict states into th...

Despite a body of literature focusing on the functionality of modern and stylistically distinct projectile points, comparatively little attention has been paid to quantifying the functionality of the early stages of projectile use. Previous work identified a simple ballistics measure, the Tip Cross-Sectional Area, as a way of determining if a given class of stone points could have served as eff...

We study the rapidity losses in central heavy-ion collisions from AGS to RHIC energies with the mean rapidity determined from the projectile net-baryon distribution after collisions. The projectile net-baryon distribution in the full rapidity range was obtained by removing the target contribution phenomenologically at forward rapidity region from the experimental net-baryon measurements and tak...

The study and treatment, from a physiological and mechanical standpoint, of projectile vomiting and of enteric colic in infants, may solve many obscure and puzzling problems. Some of the factors entering into their solution would appear to be (1) the capacity of the stomach and intestines, (2) their motor mechanisms of digestion, and (3) the volume and character of the intragastric and intra-in...