The aerospace industry has long been interested in metal architected structures. Starting with metal foam (an aperiodic pattern) in the 1960s, and honeycomb (a 2D pattern, extruded), metal additive manufacturing (AM) has pushed the boundaries further with 3D periodic structures, often referred to as lattices.

These lattices are characterized by their lightweight yet strong composition and are made up of different key parameters: unit cell geometry, material, density and cells size and number. According to Yin et al. [1], lattice patterns are categorized into 2D and 3D families. The 3D patterns further divide into four categories: truss-based, plate-based, shell-based, and hierarchical. These lattices have primarily been studied for their mechanical properties and energy absorption capabilities.

In recent years, researchers have conducted various tests on different types of lattices under quasi-static compression for various materials, including polymers and metals, generally with a focus on 316L steel and Ti6Al4V alloy. Al-Ketan et al. [2] specifically examined metal lattices and found that shell-based lattices exhibited a higher plateau stress compared to any other 3D categories during quasi-static compression. The TPMS (Triple Periodic Minimal Surface) subcategory of 3D shell-based lattices emerged as a promising candidate for enhanced energy absorption due to its potential for further densification. The literature also highlights the significance of density and cell size in determining the energy absorption capacity of lattices (see for example Mishra et al. [3] and Yin et al. [4]).

While most of the experimental results discussed previously have been obtained under quasi-static loading rates, only a few studies have explored the response of these structures to high loading rates.

In this communication, we will experimentally compare the quasi-static and dynamic effects of TPMS metallic structures under compressive loading. Three specific TPMS lattices—Primitive, Gyroid, and Diamond—will be studied. The samples are printed using additive manufacturing (LPBF technology) and Inconel 718 powder. Each sample consists of a 5mm cell size, with a 3x3x6 cell arrangement and a 25% density. The tests are conducted on quasi-static and dynamic tensile test machines. To analyze the strain localization process, high-speed imaging and local stereo digital correlation are used, as suggested by Singh et al. [5] in their numerical results, to detect dynamic inertia and out-of-plane effects.

Among others, the test results analysis allows a comparison of the stress plateau between the different TPMS lattices and between QS and dynamic loadings. Then, the results revealed that the Gyroid and Diamond structures exhibited the highest stress levels. Calculating the energy absorption from the experimental curves demonstrated that the Gyroid structure absorbed (COMBIEN) more than the Diamond ones. The development of a non-linear Finite Element numerical model is under progress to compare its predictions with the experimental results.

[1] Hanfeng Yin, Review on lattice structures for energy absorption properties, 2023

[2] Oraib Al-Ketan, Topology-mechanical property relationship of 3D printed strut, skeletal, and sheet-based periodic metallic cellular materials, 2018

[3] Ashish Kumar Mishra, Effect of cell size and wall thickness on the compression performance of triply periodic minimal surface-based AlSi10Mg lattice structures, 2023

[4] Hanfeng Yin, Crushing behavior and optimization of sheet-based 3D periodic cellular structures, 2020

[5] Agyapal Singh, Highly strain-rate sensitive and ductile composite materials combining soft with stiff TPMS polymer-based interpenetrating phases, 2024