Terminal ballistics study multivariate behavior and aftermath of projectile and target interactions. Tests and models are often based on monolithic armors, however, layered and spaced armors are common in real world applications. Such configurations add complexities that require research to understand their effects on terminal ballistics. The ballistic limit velocity (V50) represents the speed where armor perforation probability is 50%. It is used for quantitative comparison of protection capabilities for different armors. This research studied the V50 of spaced and layered A36 steel armors against fragment simulating projectiles (FSPs). Four methods for estimating armor V50 were evaluated and compared to experimental data. The first two methods were analytical methods from literature, the third was finite element (FE) simulations in EPIC, and the fourth was a Monte Carlo method developed in this research. The Monte Carlo method using 100,000 iterations was the most accurate and efficient of all methods.

Approved for public release; distribution in unlimited. / The International Space Station (ISS) must be able to withstand the hypervelocity impacts of micrometeoroids and orbital debris that strike its many surfaces. In order to design and implement shielding which will prevent hull penetration or other operational losses, NASA must first model the orbital debris and micrometeoroid environment. Based upon this environment, special multi-stage shields called Whipple and Enhanced Stuffed Whipple Shields are developed and implemented to protect ISS surfaces. Ballistic limit curves that establish shield failure criteria are determined via ground testing. These curves are functions of material strength, shield spacing, projectile size, shape and density, as well as a number of other variables. The combination of debris model and ballistic limit equations allows NASA to model risk to ISS using a hydro-code called BUMPER. This thesis modifies and refines existing ballistic limit equations for U.S. Laboratory Module shields to account for the effects of projectile (debris/ micro-meteoroid) densities. Using these refined ballistic limit equations this thesis also examines alternative shielding materials and configurations to optimize shield design for minimum mass and maximum stopping potential, proposing alternate shield designs for future NASA ground testing. A final goal of this thesis is to provide the Department of Defense a background in satellite shield theory and design in order to improve protection against micrometeoroid and orbital debris impacts on future spacebased national systems. / Lieutenant, United States Navy

Accidents when using or storing explosives can lead to a large number of casualties and injuries. Hence, it is of vital importance, in all countries, to know the risk and act responsibly when working with explosives.  A model for evaluating the risk for fragment-induced injuries from grenade detonation is created starting from experimental data of three different types of grenades. The grenades differ in shape, type of explosives and design. The experiments were conducted shooting the grenades on a wooden target and the fragments from the grenade detonation were collected by witness packages. The witness packages have a layered structure of aluminum plates and polystyrene foam. The collected fragments are weighted and the number of perforated plates for each fragment are counted. From the number of perforated plates the impact velocities of the fragments are calculated and ballistics is then used to obtain the initial velocity of the fragments. Fragmentation is regarded as a stochastic event and a distribution will more correctly describe the variation in shapes and sizes of the fragments.  All data obtained in the experiment are evaluated and used to create distributions describing the fragmentation of the grenades.  The fragmentized objects are accelerated by the detonation and will, under the influence of the medium, decreases their velocities. The velocity of the fragmentized objects are compared to criterions for skin perforations developed in the 20th century.  According to a risk assessments manual, develop by the Swedish defense research agency (FOI), the risk of severe injury can be regarded as acceptable when it occurs one in a million detonations. The distance where only one fragment in one million detonations has the ability to perforate bare skin, according to the injury criterions, is calculated using the developed model.  For the three tested grenades the distance at which the injury is acceptable (safety distance) did vary between 55 m and 240 m. The variation in safety distances is assumed to be due to design variation between the three grenades and also dependent on the model for injury criteria that was used. / Det är för alla länder viktigt att veta riskerna med de sprängmedel och ammunition som förvaras och används av deras försvarsmakter. Olyckor som kan uppstå vid förvaring och användning av dessa vapen kan leda till omfattade skador på personer i omgivningen. En modell för att beräkna riskerna för skador från fragmenterade föremål från en detonation har skapats från experiment med tre olika typer av granater. De tre granaterna varierar i form, typ av sprängmedel samt den övergripande designen. Experimenten genomfördes genom skjuta de olika granaterna mot ett mål i trä, fragmenten som skapades vid detonationen fångades sedan upp av vittnespaket. Vittnespaket har en struktur bestående av flera lager aluminiumplåtar och frigolit. Fragment som fångats av dessa paket vägs och från antalet perforerade plåtar räknas.  Från antalet perforerade plåtar kan anslagshastigheten för fragmentet beräknas, ballistik används sedan för att beräkna den initiala hastigheten för fragmentet. Från den data som erhållits av experimentet skapas en fördelning av möjliga massor och en för möjliga hastigheter för fragmenten. Fördelningarna används för att beskriva problemet, då fragmentering anses vara en stokastisk process. Fragment som accelererats av detonationen kommer bromsas genom att dessa interagerar med mediet de färdas i. Hastigheten som fragmenten har vid olika distanser från detonationen jämförs med villkor för hudperforering som utvecklats under 1900-talet. Enligt en riskmatris utvecklad av Totalförsvarets forskningsinstitut FOI, anses risken för alvarlig skada vara accepterat om skadan inte uppstår oftare än en gång på en miljon fall. Avståndet där endast ett fragment per en miljon detonerade granater har en hastighet tillräckligt hög för att perforera hud beräknas av modellen. För de testade granaterna varierade detta avstånd mellan 55 och 240 m. Skillnaden i avstånd tros bero på skillnader i granaternas är designade, samt vilket villkor för hudperforering som används.