The effect of impact loading on the mechanical properties and energy absorption of aluminum nanofoam

نوع: Type: Thesis

مقطع: Segment: masters

عنوان: Title: The effect of impact loading on the mechanical properties and energy absorption of aluminum nanofoam

ارائه دهنده: Provider: Behrad Tutunchi

اساتید راهنما: Supervisors: Amir Rezaei Sameti

اساتید مشاور: Advisory Professors:

اساتید ممتحن یا داور: Examining professors or referees: Mostafa Maghdasi - Fereydoun Rezaei

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

مکان ارائه: Place of presentation: 44

چکیده: Abstract: .Aluminum nanofoam, as an advanced structural material with a unique cellular architecture, offers an optimal combination of low density and high mechanical strength. By significantly reducing structural weight, this material enhances the efficiency of engineering systems and decreases static loads imposed on structures. Its porous architecture enables uniform distribution of impact-induced energy throughout the volume, preventing stress concentration at localized points and thereby improving impact resistance. In this study, the mechanical behavior and energy absorption capacity of aluminum nanofoam under impact loading were comprehensively investigated using molecular dynamics simulations. The primary objective was to evaluate the influence of microstructural parameters, geometric characteristics, and loading conditions on the dynamic response of this porous structure. Specifically, the effects of relative density, specimen size, initial temperature, ligament sizes, number of grains in the initial crystalline structure, and final impact pressure were systematically and comparatively examined. The results indicate that increasing relative density leads to higher Young’s modulus, yield stress, acoustic wave propagation velocity, and absorbed energy density, while compressive strain capacity and energy absorption efficiency decrease. This behavior is attributed to increased structural stiffness and reduced deformability. The investigation of specimen size effects revealed that larger samples exhibit enhanced compressive strength, improved structural stability, and greater energy absorption capacity, while simultaneously mitigating boundary effects and localized instabilities. Temperature-dependent analyses demonstrated that aluminum nanofoam exhibits superior mechanical performance at lower temperatures. Elevated temperatures induce thermal softening, resulting in reduced Young’s modulus and yield stress and accelerating cell collapse mechanisms. Furthermore, increasing strut thickness enhances load transfer pathways and promotes more uniform stress distribution, thereby improving overall stiffness and structural stability while preventing local buckling and premature failure. Analysis of the energy absorption mechanisms showed that energy dissipation primarily occurs through plastic deformation, internal friction, and conversion into thermal energy. At the atomic scale, these processes are accompanied by phase transformations, dislocation nucleation and interactions, and the progressive collapse of porous cells. Overall, the findings suggest that simultaneous optimization of microstructural parameters, geometric features, and loading conditions plays a critical role in designing lightweight materials with high energy absorption capacity for protective and impact-resistant applications

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