Ballistic Resistance of Sandwich Panels with Corrugated Cores Subjected to High-Velocity Impact

نوع: Type: Thesis

مقطع: Segment: PHD

عنوان: Title: Ballistic Resistance of Sandwich Panels with Corrugated Cores Subjected to High-Velocity Impact

ارائه دهنده: Provider: Mohammad Solooki

اساتید راهنما: Supervisors: Dr. Ali Alavi Nia

اساتید مشاور: Advisory Professors:

اساتید ممتحن یا داور: Examining professors or referees: Dr. Alireza Sabet & Dr. Hossein Khodarahmi

زمان و تاریخ ارائه: Time and date of presentation: 2026

مکان ارائه: Place of presentation: آمفی تئاتر دانشکده مهندسی

چکیده: Abstract: This dissertation aims to enhance the ballistic resistance of sandwich panels by investigating and optimizing a novel configuration featuring hybrid metal–polymer face sheets and corrugated cores. The primary novelty lies in the simultaneous employment of three strengthening strategies: semi-cylindrical and semi-spherical corrugated cores for projectile trajectory deviation, polyurea face sheets as energy-absorbing layers, and core multilayering to compensate for corrugation structural weaknesses. Utilizing the Taguchi design of experiments method, 18 panel types were defined and fabricated based on layer thicknesses, corrugation radius (10 and 20 mm), number of core layers (single and double), and projectile impact location (crest, valley, and wave slope). Ballistic tests were conducted using a 25 mm gas gun, and the ballistic limit velocities of the structures were determined. Furthermore, three-dimensional finite element simulations were performed in LS-DYNA, and following validation, the ballistic limit velocity was extracted for all 18 configurations. The contribution of each layer to projectile velocity reduction was also quantified step by step. Finally, using the Taguchi optimization method, three objective functions—target strength, target mass, and the ratio of absorbed energy to target mass—were simultaneously analyzed to determine the optimal thicknesses. The results revealed that the primary energy absorption mechanisms include plastic deformation of the core, petaling in the rear layer, and the high ductility of polyurea. The semi-cylindrical core exhibited superior resistance compared to the semi-spherical core, increasing the ballistic limit velocity by approximately 14.1%. Impact at the mid-curvature (wave crest) yielded the best performance, enhancing the ballistic limit by up to 24% compared to impact at the valley. The use of a second core layer resulted in ballistic resistance improvements of approximately 3.2% for the semi-cylindrical core and approximately 6.7% for the semi-spherical core. The polyurea layer, by dissipating energy and acting as a barrier against crack propagation, increased the ballistic limit velocity by 22.32%. Optimization analysis identified polyurea thickness, with an influence coefficient of 35.5%, as the most significant factor in enhancing ballistic strength, followed by corrugation radius (26.1%) and aluminum thickness (25.6%). The optimal thicknesses for the front aluminum face sheet, polyurea, aluminum core, polyurea, and rear aluminum face sheet were determined as 2, 1, 0.5, 1, and 2 mm, respectively. In conclusion, this research, by introducing a novel sandwich panel configuration, has taken an effective step toward the development of lightweight and efficient armor systems, significantly enhancing ballistic resistance (by up to approximately 30% in certain configurations) while minimizing the added mass.