Abstract
The main aim of this article is the analysis of the deformation process of regular cell structures under quasi-static load conditions. The methodology used in the presented investigations included a manufacturability study, strength tests of the base material as well as experimental and numerical compression tests of developed regular cellular structures. A regular honeycomb and four variants with gradually changing topologies of different relative density values have been successfully designed and produced in the TPU-Polyflex flexible thermoplastic polyurethane material using the Fused Filament Fabrication (FFF) 3D printing technique. Based on the results of performed technological studies, the most productive and accurate 3D printing parameters for the thermoplastic polyurethane filament were defined. It has been found that the 3D printed Polyflex material is characterised by a very high flexibility (elongation up to 380%) and a non-linear stress-strain relationship. A detailed analysis of the compression process of the structure specimens revealed that buckling and bending were the main mechanisms responsible for the deformation of developed structures. The Finite Element (FE) method and Ls Dyna software were used to conduct computer simulations reflecting the mechanical response of the structural specimens subjected to a quasi-static compression load. The hyperelastic properties of the TPU material were described with the Simplified Rubber Material (SRM) constitutive model. The proposed FE models, as well as assumed initial boundary conditions, were successfully validated. The results obtained from computer simulations agreed well with the data from the experimental compression tests. A linear relationship was found between the relative density and the maximum strain energy value.
Highlights
Over the last two decades, a growing development of additive manufacturing (AM) techniques has been observed [1,2,3,4]
This name comes from the technical solution used during the object building process, where the thermoplastic material is melted and extruded through a nozzle to build up the layers that gradually make up a complete part
Bowden feed mechanism, where the distance between the feed mechanism and the end of the extruder a Bowden feed mechanism, where the distance between the feed mechanism and the end of the is relatively greater, the use of a highly flexible filament is not recommended
Summary
Over the last two decades, a growing development of additive manufacturing (AM) techniques has been observed [1,2,3,4]. Hedayati et al [34] presented a mechanical response of 3D printed honeycomb specimens made from PLA under quasi-static in-plane compression tests They analysed the influence of the specimen wall thickness value on the deformation process. Yang et al [44] carried out tensile and compression tests on specimens, taking auxetic topologies into account They analysed the mechanical response of a structure with gradually changing elementary singular cell topology to the deformation process. Bodaghi et al [47] have conducted interesting studies on soft PLA material manufactured additively with the use of FFF They revealed that the singular cell shape, direction, type, and magnitude of mechanical load affects the metamaterial’s anisotropic response and its instability characteristics. On the results obtained,topology the influence the structure topology on its deformation history plot was discussed
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