Investigating the effect of various cellular configurations and geometrical parameters on the strength-to-weight ratio of honeycomb cores designed for Additive Manufacturing.

Abstract

Different industries, mostly aerospace and automotive, focus on designing components to increase their strength-to-weight ratio and reduce manufacturing times. Honeycomb structures are the most suitable solution for this demand. The different researchers made a bulk of investigations mainly focused on evaluating and analyzing the different cellular configurations. Also, additive manufacturing (AM) is becoming their 1st choice to print these honeycomb structures. The honeycomb structure's geometrical parameters i.e. cell wall length, cell wall thickness, and height are critical factors and greatly affect its strength. In the presented investigation, 48 honeycomb structures of different cellular configurations including hexagon, over-expanded hexagon, and square shape by varying geometrical parameters were manufactured using FDM (fused deposition modeling) including 16 samples of each shape. We obtain a new degree of control over the cellular architecture of honeycomb structures by utilizing cutting-edge AM techniques, which improve mechanical characteristics and reduce weight. The material used for printing these samples is PLA+. Testing was performed using out-of-plane loading to investigate the structure strength and analyzed using Taguchi and ANOVA (Analysis of Variance). Four levels of each i.e., the height of core 12.7, 25.4, 38.1, and 50.8mm, cell wall length 3, 6, 9, and 12 mm, and cell wall thickness 0.5, 1, 1.5, and 2 mm are considered for designing and printing samples having 80x80 mm crosssectional area chosen by following ASTM C365 standard for compression testing. Moreover, multi-objective optimization is performed to optimize the strength-to-weight ratio and manufacturing cost using the Taguchi method. Hexagonal cellular configuration is selected to have better configuration than square and over-expanded because hexagonal shape structures are less costly have less printing time, contain less weight, give better strength-to-weight ratios, and prove more economical than others. And optimum geometrical parameters resulting from ANOVA for hexagon shape are the height of core 12.7 mm, cell wall length 6 mm, and cell wall thickness 1mm to increase strength-to-weight ratios and reduce manufacturing cost. Thus, it would be fruitful to develop more economical structures or components with less weight and high strength that are undergoing compression loading.