An Experimental Investigation of Failure Modes and Deformation Patterns in 2D Sandwich Architected Materials

Abstract

This research study aimed to develop and execute a systematic experimental protocol for testing different variations of 2D honeycomb and diamond sandwich architected structures. Each sandwich structure was tested under three different loading conditions: local compression (3-point bending), uniform compression (quasi-static compression), and low-velocity impact loading. The data from the experiments was used to address four main research questions: how do the tested lattices fail? What aspects of failure are reproducible? What effect does micro-architecture have on failure? What are the differences between dynamic and static loading for the tested sandwich structures? The designed 2D architected structures were varied by changing a specific angle in their unit cell structure. For honeycomb the variations were 15°, 30°, 45°, and functional grading. For diamond it was 45°, 90°, 120°, and functional grading. The load response during static loading for each category and variation was also observed to have underlying patterns. For the honeycomb, 45° and 90° diamond variations, a consistent pattern of a Type II structure was observed. This represents structures with initial high energy absorbed over small strain followed by reduction in energy once failure begins in the structure. A Type I structural response was observed for the 120° and functionally graded diamond variations. This is represented by a steady increase in energy absorbed over large strains. The work done in this study shows a systematic approach to understanding the behavior of 2D architected materials under different types of loading conditions. This can be applied to other architected materials and help facilitate modeling and simulation grounded in real-world data.