Abstract
Significant weight savings in parts can be made through the use of additive manufacture (AM), a process which enables the construction of more complex geometries, such as functionally graded lattices, than can be achieved conventionally. The existing framework describing the mechanical properties of lattices places strong emphasis on one property, the relative density of the repeating cells, but there are other properties to consider if lattices are to be used effectively. In this work, we explore the effects of cell size and number of cells, attempting to construct more complete models for the mechanical performance of lattices. This was achieved by examining the modulus and ultimate tensile strength of latticed tensile specimens with a range of unit cell sizes and fixed relative density. Understanding how these mechanical properties depend upon the lattice design variables is crucial for the development of design tools, such as finite element methods, that deliver the best performance from AM latticed parts. We observed significant reductions in modulus and strength with increasing cell size, and these reductions cannot be explained by increasing strut porosity as has previously been suggested. We obtained power law relationships for the mechanical properties of the latticed specimens as a function of cell size, which are similar in form to the existing laws for the relative density dependence. These can be used to predict the properties of latticed column structures comprised of body-centred-cubic (BCC) cells, and may also be adapted for other part geometries. In addition, we propose a novel way to analyse the tensile modulus data, which considers a relative lattice cell size rather than an absolute size. This may lead to more general models for the mechanical properties of lattice structures, applicable to parts of varying size.
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References
Aremu A, Ashcroft I, Wildman R, Hague R, Tuck C, Brackett D (2013) The effects of bidirectional evolutionary structural optimization parameters on an industrial designed component for additive manufacture. P I Mech Eng B- J Eng 227(6):794–807
Chahine G, Smith P, Kovacevic R (2010) Application of topology optimization in modern additive manufacturing in Solid Freeform Fabrication Symposium, pp 606–618
Brackett D, Ashcroft I, Hague R (2011) Topology optimization for additive manufacturing, in Solid Freeform Fabrication Symposium:348–362
Gardan N (2014) Knowledge management for topological optimization integration in additive manufacturing. Int J Manuf Eng, vol:2014
Brackett D, Ashcroft I, Wildman R, Hague R (2014) An error diffusion based method to generate functionally graded cellular structures. Comput Struct 138(0):102–111
Yan C, Hao L, Hussein A, Young P, Raymont D (2014) Advanced lightweight 316l stainless steel cellular lattice structures fabricated via selective laser melting. Mater Des 55:533–541
Smith M, Guan Z, Cantwell W (2013) Finite element modelling of the compressive response of lattice structures manufactured using the selective laser melting technique. Int J Mech Sci 67:28–41
Ushijima K, Cantrell WJ, Mines RAW, Tsopanos S, Smith M (2011) An investigation into the compressive properties of stainless steel micro-lattice structures. J Sandw Struct Mat 13:303–329
Fleck NA, Deshpande VS, Ashby MF (2010) Micro-architectured materials past, present and future. Proc R Soc A 466:2495–2516
Kooistra GW, Deshpande VS, Wadley HN (2004) Compressive behavior of age hardenable tetrahedral lattice truss structures made from aluminium. Acta Mater 52:4229–4237
Gorny B, Niendorf T, Lackmann J, Thoene M, Troester T, Maier H (2011) In situ characterization of the deformation and failure behavior of non-stochastic porous structures processed by selective laser melting. Mat Sci Eng A-Struct 528:7962–7967
Brennan-Craddock J, Brackett D, Wildman R, Hague R (2012) The design of impact absorbing structures for additive manufacture,J Phys Conference Series, vol. 382, no. 1,012042
Yan C, Hao L, Hussein A, Raymont D (2012) Evaluations of cellular lattice structures manufactured using selective laser melting. Int J Mach Tool Manu 62:32
Hasan R (2013) Progressive collapse of titanium alloy micro-lattice structures manufactured using selective laser melting PhD thesis. University of Liverpool
Tsopanos S, Mines RAW, McKown S, Shen Y, Cantrell WJ, Brooks W, Sutcliffe CJ (2010) The influence of processing parameters on the mechanical properties of selectively laser melted stainless steel microlattice structures J Manuf Sci Eng (ASME), vol. 132, p. 041011
Shen Y, McKown S, Tsopanos S, Sutcliffe CJ, Mines RAW, Cantwell WJ (2010) The mechanical properties of sandwich structures based on metal lattice architectures. J Sandw Struct Mat 12:159–180
Gibson L, Ashby M (1997) Cellular Solids: Structure and properties. Cambridge University Press
Ashby M (2006) The properties of foams and lattices. Philos T Roy Soc A 364:15–30
Timoshenko SP, Goodier JN (1970) Theory of Elascticity. McGraw-Hill, New York
Roark RJ, Young WC (1976) Formulas for stress and strain. McGraw-Hill, London
Dillard T (2004) Caractérisation et simulation numérique du comportement Mécanique des mousses de nickel: morphologie tridimensionnelle, réponse élastoplastique et rupture PhD thesis Ecole Nationale Supérieure des Mines de Paris
Queheillalt DT, Katsumura Y, Wadley HN (2004) Synthesis of stochastic open cell ni-based foams. Scripta Mater 50:313–317
Deshpande VS, Fleck NA (2001) Collapse of truss core sandwich beams in 3-point bending. Int J Solids Struct 38:6275–6305
Yan C, Hao L, Hussein A, Bubb SL, Young P, Raymont D (2014) Evaluation of light-weight alsi10mg periodic cellular latticestructures fabricated via direct metal laser sintering. J Mater Process Tech 214:856–864
Deshpande V, Ashby MF, Fleck NA (2001) Foam topology: bending versus stretching dominated architectures. Acta Mater 49:1035–1040
Khaderi S, Deshpande V, Fleck N (2014) The stiffness and strength of the gyroid lattice. Int J Solids Struct 51:3866–3877
Kalidindi S, Abusafieh A, El-Danaf E, Accurate characterization of machine compliance for simple compression testing (1997). Exp Mech 37(2):210–215
(2007). In: Boyer R, Welsch G, Collings E (eds) Materials Properties Handbook: Titanium Alloys. ASM International
In: Donachie M (ed) Titanium A Technical Guide. ASM International, 200
Vrancken B, Thijs L, Kruth J-P, Humbeeck JV (2012) Heat treatment of ti6al4v produced by selective laser melting: Microstructure and mechanical properties. J Alloy Compd 541:177–185
Facchini L, Magalini E, Robotti P, Molinari A, Höges S, Wissenbach K (2010) Ductility of a ti-6al-4v alloy produced by selective laser melting of prealloyed powders. Rapid Prototyping J 16:450–459
McKown S, Shen Y, Brookes W, Sutcliffe C, Cantwell W, Langdon G, Nurick G, Theobald M (2008) The quasi-static and blast loading response of lattice structures. Int J Impact Eng 35:795–810. Twenty-fifth Anniversary Celebratory Issue Honouring Professor Norman Jones on his 70th Birthday.
Simonelli M (2014) Microstructure evolution and mechanical properties of selective laser melted Ti-6Al-4V PhD thesis. Loughborough University
Blazy J-S, Marie-Louise A, Forest S, Chastel Y, Pineau A, Awade A, Grolleron C, Moussy F (2004) Deformation and fracture of aluminium foams under proportional and non proportional multi-axial loading: statistical analysis and size effect. Int J Mech Sci 46:217–244
Ramamurty U, Paul A (2004) Variability in mechanical properties of a metal foam. Acta Mater 52:869–876
Acknowledgments
We would like to thank Sean Smith, Ravi Aswathanarayanaswamy, Hossein Sheykh-Poor and various teams at Renishaw Plc. for the provision of the test specimens and continued support in our collaborative projects. Thanks also to Mark East, Mark Hardy and Joe White, technicians of the Additive Manufacture and 3D Printing Research Group at Nottingham. Funding was provided by Innovate UK, formerly the UK Technology Strategy Board (TSB).
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Maskery, I., Aremu, A., Simonelli, M. et al. Mechanical Properties of Ti-6Al-4V Selectively Laser Melted Parts with Body-Centred-Cubic Lattices of Varying cell size. Exp Mech 55, 1261–1272 (2015). https://doi.org/10.1007/s11340-015-0021-5
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DOI: https://doi.org/10.1007/s11340-015-0021-5