Mechanical characterization and numerical modeling of laser-sintered TPE lattice structures

Abstract

Additive Manufacturing provides the opportunity to produce tailored and complex structures economically. The use of lattice structures in combination with a thermoplastic elastomer enables the generation of structures with configurable properties by varying the cell parameters. Since there is only little knowledge about the producibility of lattice structures made of TPE in the laser sintering process and the resulting mechanical properties, different kinds of lattice structures are investigated within this work. The cell type, cell size and strut thickness of these structures are varied and analyzed. Within the experimental characterization of Dodecahedron-cell static and cyclic compression tests of sandwich structures are focused. The material exhibits hyperelastic and plastic properties and also the Mullins-Effect. For the later design of real TPE structures, the use of numerical methods helps to reduce time and costs. The preceding experimental investigations are used to develop a concept for the numerical modeling of TPE lattice structures. Graphic abstract

Free Vibration Characteristics of Multi-Material Lattice Structures

“…Although different types of conventional manufacturing techniques have been considered for producing lattice structures, they are not optimal for production since they require complex tools with precise process control and need more steps to assemble or bond to create intended lattice structures [4]. Parts with grids can be manufactured easily from discrete unit cells with the help of additive manufacturing processes [5].…”

Low Impact Velocity Modeling of 3D Printed Spatially Graded Elastomeric Lattices

“…For instance, metallic lattice research has widely focused on Ti-6Al-4V, AlSi10Mg, and 316L stainless steel through electron beam melting (EBM) and selective laser melting (SLM) [ 4 , 5 , 7 ]; conversely, polymeric lattices studies have mostly concentrated on polylactic acid (PLA), acrylonitrile butadiene styrene (ABS), and nylon-based powders by using selective laser sintering (SLS) and fused deposition modeling (FDM) [ 4 , 5 , 7 , 8 ]. For instance, ABS lattices have also been fabricated via stereolithography (SLA) with photo-polymeric resin [ 9 ], and thermoplastic elastomer (TPE) has been printed via SLS [ 10 ].…”

“…The capabilities of AM technologies have also allowed various researchers to build lattices with elevated levels of complexity. Indeed, several works have investigated enclosed truss-based unit cell geometries based on cubic, diamond, triangular, pyramidal, body-centered cubic (BBC), dodecahedron, octahedral, tetrahedron, and tetrakaidecahedron or Kelvin cell [ 5 , 7 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 ], among many other geometries. Surface-based geometries and triply periodic minimal surface (TPMS) configurations as a spherical shell, gyroid, IWP, OCTO, Schwarz, TPMS diamond, and TPMS primitive have also been studied [ 5 , 7 , 14 , 15 , 29 , 30 , 31 , 32 ].…”

“…Likewise, modifications and combinations of the basic truss-based geometries can also be found in the literature, such as the re-entrant dodecahedron, reinforced BCC, octet, and face-body-centered cubic (FBCC), as well as structures with varying distribution of the volume fraction of each unit cell in the 3D design domain, also known as spatially graded lattices [ 5 , 7 , 9 , 18 , 22 , 24 , 25 , 26 , 27 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 ]. The manufacturability of some of the aforementioned geometries could be limited by the post-processing method, such as heat treatment, curing, or cleaning [ 10 ].…”

“…Lattice structures are mainly evaluated by their stiffness and energy absorption capabilities through quasi-static compression tests [ 9 , 10 , 11 , 12 , 13 , 14 , 16 , 17 , 19 , 22 , 27 , 30 , 34 , 35 , 36 , 37 , 38 , 39 , 41 ] and dynamic compression tests [ 18 , 22 , 23 , 25 , 35 , 42 ]. The behavior of the lattices is mainly affected by the geometry of its unit cell, the relative density, and the properties of the parent material [ 4 , 28 , 43 , 44 ]; therefore, multiple tests are carried out on the base (solid) material to characterize its mechanical behavior under tensile, flexural, and compressive loads [ 8 , 11 , 13 , 14 , 19 , 27 , 29 , 31 , 34 , 35 , 36 , 38 , 39 , 42 , 45 , 46 ], commonly via universal testing machines (UTM).…”