Influence of Processing Parameters and Testing Temperatures on Thermomechanical Coupling Properties of Additively Manufactured Ti6al4v-Eli Auxetic Structures: Experimental and Numerical Study

Abstract

This study investigates the effects of processing parameters and testing temperatures on the mechanical properties of auxetic structures fabricated from Ti6Al4V-ELI using Laser Powder Bed Fusion. Three distinct sets of process parameters (Set 1: 50 W-400 mm s-1, Set 2: 75 W-800 mm s-1, and Set 3: 100 W-1200 mm s-1) were employed to fabricate peanut-shaped auxetic structures, which were subsequently tested at temperatures of -20 degrees C, 25 degrees C, 100 degrees C, and 200 degrees C. Digital image correlation was employed for detailed strain analysis, while the fabricated auxetic structures were further characterized using x-ray diffraction, scanning electron microscopy, and Vickers hardness testing. The experimental results were validated through thermomechanical finite element simulations, followed by a parametric study to examine the influence of geometric parameters and testing temperature on the mechanical performance of the auxetic structures. According to the test results, Set 3 exhibited the highest peak force, whereas Set 1 demonstrated the lowest. Furthermore, Set 2 achieved maximum elongation at 200 degrees C. The investigated structures exhibited auxetic behavior under varying testing temperatures and processing parameters. The structure fabricated with Set 1 parameters demonstrated the highest auxetic response, whereas that produced with Set 3 parameters exhibited the lowest. The parametric study revealed that the mechanical properties of auxetic structures are influenced by the auxetic unit cell dimensions, pattern distribution, and testing temperature while also being sensitive to processing parameters, thus offering the potential for tailored optimization and guiding future material design.