Mechanical Properties of Ti-6Al-4V Selectively Laser Melted Parts with Body-Centred-Cubic Lattices of Varying cell size

Abstract

. (2015) Mechanical properties of Ti-6Al-4V selectively laser melted parts with body-centred-cubic lattices of varying cell size. Experimental Mechanics, 55 (7). pp. 1261 -1272 . ISSN 1741 -2765 Access from the University of Nottingham repository: http://eprints.nottingham.ac.uk/31973/1/Accepted_manuscript.pdf Copyright and reuse:The Nottingham ePrints service makes this work by researchers of the University of Nottingham available open access under the following conditions. This article is made available under the University of Nottingham End User licence and may be reused according to the conditions of the licence. For more details see: http://eprints.nottingham.ac.uk/end_user_agreement.pdf A note on versions:The version presented here may differ from the published version or from the version of record. If you wish to cite this item you are advised to consult the publisher's version. Please see the repository url above for details on accessing the published version and note that access may require a subscription.For more information, please contact eprints@nottingham.ac.uk 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.

A mechanical property evaluation of graded density Al-Si10-Mg lattice structures manufactured by selective laser melting

“…The models they developed were originally applied to experimental results from honeycomb 85 and foam structures, but they have more recently been used in the investigation of lattices made by AM [28][29][30][31].…”

Understanding the effect of laser scan strategy on residual stress in selective laser melting through thermo-mechanical simulation

“…Owing to its ability to incorporate advanced design techniques, such as topology optimisation [3,4] and lattice structures into components [5], and individual customisation, SLM has gained significant attention from many industrial sectors, in particular aerospace and automotive. Despite its great potential, technical barriers prevent manufacture 'right first time' and impose several manufacturing constraints that reduce design freedoms and design optimization unnecessarily.…”

Quantification and characterisation of porosity in selectively laser melted Al–Si10–Mg using X-ray computed tomography

“…These include a level of design freedom which is unconstrained by the limitations of tool accessibility [1,2]. Complex shapes, including those that stem from the use of weight saving topology optimisation [3][4][5][6] or lattice structures [7][8][9][10][11][12][13][14][15][16] can be manufactured with no additional cost or energy expenditure compared to traditional forms; in many cases the advantages of AM lie in its facility to produce shapes that are not achievable by other means. Additional benefits include low material wastage and a reduction of the number of manufacturing steps [1,2,17,18].…”