Inspired from cellular materials found in nature, lattice structures are tailor-made porous materials that have been made possible by the recent improvement in Additive Manufacturing. Their custom tailoring made possible the creation of fault-tolerant materials from scratch. Inspired by the structure of natural materials such as bone, it is making use of sacrificial linkages inside of the lattice structure to absorb energy and distribute damage before its catastrophic failure. It enhances structural resilience and energy absorption under stress, making it suitable for structural monitoring applications and energy absorbing structures. This research aims at designing and analyzing three new 3-dimensional fault-tolerant lattices. These three lattices are strut lattices based on a Octet-Truss, BCCXYZ and Cubic unit cell. They use a combination of two different beam thicknesses to create sacrificial bonding inside of the structure. The numerical analysis is conducted using a custom-made algorithm using a beam element model and adapted to the needs of fault-tolerance simulation. It is used to determine the optimal values of beam thickness for energy absorption or for fault-tolerant zone and to compare the three lattices. An experimental analysis is also conducted using samples printed in PA2200 by Selective Laser Sintering. The research puts in evidence the fault-tolerant nature of three new lattices. The structure based on a cubic unit cell performed the best overall, followed by the one based on a BCCXYZ unit cell. The structure based on the Octet-Truss unit cell had a fault-tolerant zone but poor overall performance. At the end, potential applications taking advantage of the fault-tolerant behavior are discussed, with an illustrative example in aerospace.
Ispirate ai materiali cellulari presenti in natura, le strutture reticolari (lattice structures) sono materiali porosi su misura, resi possibili dai recenti sviluppi della produzione additiva. La loro personalizzazione ha permesso la creazione di materiali con tolleranza ai guasti (fault-tolerance) a partire da zero. Ispirandosi alla struttura di materiali naturali come l'osso, esse utilizzano collegamenti sacrificabili all'interno della struttura reticolare per assorbire energia e distribuire il danno prima del cedimento catastrofico. Questo migliora la resilienza strutturale e l'assorbimento di energia sotto stress, rendendole adatte per applicazioni di monitoraggio strutturale e per strutture che assorbono energia. Questa ricerca mira a progettare e analizzare tre nuove strutture reticolari tridimensionali con tolleranza ai guasti. Queste tre strutture sono reticoli a traliccio basati su una cella unitaria Octet-Truss, BCCXYZ e Cubica. Utilizzano una combinazione di due spessori di travi differenti per creare legami sacrificabili all'interno della struttura. L'analisi numerica è condotta utilizzando un algoritmo personalizzato basato su un modello a elementi trave (beam element model), adattato alle esigenze della simulazione di tolleranza ai guasti. Questo modello è utilizzato per determinare i valori ottimali di spessore delle travi per l’assorbimento di energia o per la zona di tolleranza ai guasti e per confrontare i tre reticoli. È inoltre condotta un’analisi sperimentale su campioni stampati in PA2200 tramite sinterizzazione laser selettiva (Selective Laser Sintering). La ricerca evidenzia la natura tollerante ai guasti di tre nuove strutture reticolari. La struttura basata su una cella unitaria cubica ha dimostrato le migliori prestazioni complessive, seguita da quella basata su una cella unitaria BCCXYZ. La struttura basata sulla cella unitaria Octet-Truss ha presentato una zona di tolleranza ai guasti ma con prestazioni complessive inferiori. Infine, vengono discusse potenziali applicazioni che sfruttano il comportamento tollerante ai guasti, con un esempio illustrativo in ambito aerospaziale.
Design and analysis of novel 3-dimensional fault-tolerant lattice structures fabricated with selective laser sintering
Wagner, Martin
2023/2024
Abstract
Inspired from cellular materials found in nature, lattice structures are tailor-made porous materials that have been made possible by the recent improvement in Additive Manufacturing. Their custom tailoring made possible the creation of fault-tolerant materials from scratch. Inspired by the structure of natural materials such as bone, it is making use of sacrificial linkages inside of the lattice structure to absorb energy and distribute damage before its catastrophic failure. It enhances structural resilience and energy absorption under stress, making it suitable for structural monitoring applications and energy absorbing structures. This research aims at designing and analyzing three new 3-dimensional fault-tolerant lattices. These three lattices are strut lattices based on a Octet-Truss, BCCXYZ and Cubic unit cell. They use a combination of two different beam thicknesses to create sacrificial bonding inside of the structure. The numerical analysis is conducted using a custom-made algorithm using a beam element model and adapted to the needs of fault-tolerance simulation. It is used to determine the optimal values of beam thickness for energy absorption or for fault-tolerant zone and to compare the three lattices. An experimental analysis is also conducted using samples printed in PA2200 by Selective Laser Sintering. The research puts in evidence the fault-tolerant nature of three new lattices. The structure based on a cubic unit cell performed the best overall, followed by the one based on a BCCXYZ unit cell. The structure based on the Octet-Truss unit cell had a fault-tolerant zone but poor overall performance. At the end, potential applications taking advantage of the fault-tolerant behavior are discussed, with an illustrative example in aerospace.| File | Dimensione | Formato | |
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https://hdl.handle.net/10589/230596