مجتبي بهادري

Due to their unique characteristics, triply periodic minimal surfaces (TPMS) have emerged as significant an‎d noteworthy engineering structures in recent years. These structures, owing to their high surface-to-volume ratio an‎d geometric continuity, have found potential applications in energy absorption systems, impact mitigation, an‎d bioscaffolds for simulating natural body tissues. Gaining a deeper understan‎ding of the mechanical behavior of these structures under various loading conditions will lead to their optimized design. This research investigates the effects of unit cell size an‎d quasi-static strain rate on the thermo-mechanical behavior an‎d energy absorption capacity of these structures. Diamond an‎d Gyroid structures with unit cell sizes of 5 an‎d 8 mm were fabricated using the Fused Filament Fabrication (FFF) additive manufacturing technique with Polylactic acid (PLA) filament. Uniaxial compression an‎d flexural tests were conducted at four loading rates of 1, 50, 100, an‎d 200 mm/min. Finite element simulation was performed to analyze the structures’ behavior under compression. The results indicated that the Diamond structure exhibited superior mechanical performance an‎d higher energy absorption capacity compare to the Gyroid structure across all investigated loading rates. Specifically, the compressive an‎d flexural strength of the Diamond structure were 1.5 an‎d 2 times the values observed for the Gyroid, respectively, an‎d the specific energy absorption was 1.9 times higher. Increasing the strain rate led to an increase in yield stress an‎d plateau stress. Conversely, due to the self-heating phenomenon an‎d thermal softening of the PLA material, a noticeable decrease in the stiffness of the structures was observed. Structures with smaller unit cells exhibited greater sensitivity to strain rate, which is attributed to their higher relative density an‎d the involvement of a larger volume of material in load-bearing. In contrast, structures with larger unit cells experienced a more significant reduction in stiffness due to the concentration of plastic deformation in more limited regions. Structures with smaller cells at high strain rates demonstrate optimal thermos-mechanical performance an‎d higher energy absorption capacity, making them more suitable for energy absorber an‎d impact mitigation systems. Whereas structures with larger cells are more appropriate for lightweight load-bearing applications at lower loading rates.

ساخت افزايشي , سطوح كمينه دوره‌اي سه‌گانه , خواص ترمو-مكانيكي , جذب انرژي , حساسيت به نرخ بارگذاري

Additive manufacturing , Triply periodic minimal surfaces , Thermo-mechanical properties , Energy absorption , Strain rate sensitivity

Mojtaba Bahadori

Fathollah Taheri Behrooz an‎d MohmmadReza Mohammad Aliha