Date of Defense
4-6-2025 3:00 PM
Location
F1-1043
Document Type
Thesis Defense
Degree Name
Master of Science in Mechanical Engineering (MSME)
College
COE
Department
Mechanical and Aerospace Engineering
First Advisor
Dr. Sanan Husain Khan
Keywords
Ballistic impact, Fibonacci, Multi-layer aluminum, Double-nose projectiles.
Abstract
This research examines the ballistic performance of multi-layered Aluminum 2024 sheets designed with Fibonacci-inspired spacing patterns when subjected to double-nose projectile impacts. Through a numerical simulation, five configurations were studied: a monolithic reference plate (L0) with 0.82 mm thickness, and four multi-layer configurations (L1 to L4), all maintaining a constant total thickness of 1.74 mm. Three projectile types were considered Blunt-Conical (BC), Conical-Blunt (CB), and Blunt-Blunt (BB). Among these, the L1 configuration (two layers separated by a 0.1 mm gap) consistently offered the best ballistic resistance, outperforming more complex arrangements. As layer complexity increased from L1 to L4, overall performance declined, with L4 behaving similarly to the thinner monolithic L0, despite its greater number of layers and total material. Efficiency analysis highlighted that adding more interfaces brings diminishing returns; the Interface Efficiency for L4 dropped to just 17% of that seen in L1. Interestingly, the CB projectile showed strong compatibility with the L2 configuration, suggesting a geometry-specific interaction. Further evaluation of energy absorption, damage progression, and velocity ratios confirmed that reducing individual layer thickness below ~0.3 mm leads to premature failure, nullifying the advantages of additional interfaces. Overall, this study challenges the common assumption that adding more layers always enhances protection. Instead, it highlights the importance of keeping each layer thick enough and placing interfaces strategically, rather than simply increasing the number of layers.
EFFECT OF FIBONACCI-INSPIRED MULTI-LAYER ALUMINUM SHEETS UNDER DOUBLE-NOSE PROJECTILE IMPACT
F1-1043
This research examines the ballistic performance of multi-layered Aluminum 2024 sheets designed with Fibonacci-inspired spacing patterns when subjected to double-nose projectile impacts. Through a numerical simulation, five configurations were studied: a monolithic reference plate (L0) with 0.82 mm thickness, and four multi-layer configurations (L1 to L4), all maintaining a constant total thickness of 1.74 mm. Three projectile types were considered Blunt-Conical (BC), Conical-Blunt (CB), and Blunt-Blunt (BB). Among these, the L1 configuration (two layers separated by a 0.1 mm gap) consistently offered the best ballistic resistance, outperforming more complex arrangements. As layer complexity increased from L1 to L4, overall performance declined, with L4 behaving similarly to the thinner monolithic L0, despite its greater number of layers and total material. Efficiency analysis highlighted that adding more interfaces brings diminishing returns; the Interface Efficiency for L4 dropped to just 17% of that seen in L1. Interestingly, the CB projectile showed strong compatibility with the L2 configuration, suggesting a geometry-specific interaction. Further evaluation of energy absorption, damage progression, and velocity ratios confirmed that reducing individual layer thickness below ~0.3 mm leads to premature failure, nullifying the advantages of additional interfaces. Overall, this study challenges the common assumption that adding more layers always enhances protection. Instead, it highlights the importance of keeping each layer thick enough and placing interfaces strategically, rather than simply increasing the number of layers.
