Multi-axial fatigue behaviour of titanium periodic cellular structures produced by Selective Laser Melting (SLM)

Khalil Refai,Nicolas Saintier,Marco Montemurro,Charles Brugger,T Palin-Luc,A Carpinteri,F Morel

doi:10.1051/matecconf/201930003004

Abstract

Additive manufacturing techniques such as selective laser melting (SLM) allow for manufacturing periodic porous titanium structures having complex geometry. The mechanical properties of these structures with diﬀerent elementary cell (ECs) designs have been already studied in literature. However, their fatigue behaviour is not yet well understood. This work aims at proposing a numerical approach to predict the periodic cellular structures fatigue behaviour under multiaxial loadings. The approach is based on an explicit description of the EC combined to an extreme statistical analysis making use of a fatigue indicator parameter to investigate (and compare) diﬀerent EC configurations. On the other hand, the numerical model relies on the use of a general numerical homogenisation scheme to properly apply the multi-axial loading conditions to the EC at the mesoscopic scale. Results show that lattice fatigue strength is strongly aﬀected by the relative density as well as by the geometrical features of the EC.

Highlights

In the last two decades, a strong effort has been put on the development of periodic cellular structures fabricated by means of additive layer manufacturing (ALM) technology because of the advantages they offer including design freedom, high precision, and the ability to produce parts directly from a numerical model
Few studies focusing on the fatigue behaviour of these structures which aim at understanding the relationship between the elementary cell (EC) geometrical parameters and its fatigue strength are available in literature [1,2,3]
A first numerical campaign of analyses has been carried out in order to compare the fatigue strength of the different EC topologies which are summarised in Tables 1-2 for a relative density equal to 10%, i.e. ρ = 0.1

Summary

Introduction

In the last two decades, a strong effort has been put on the development of periodic cellular structures fabricated by means of additive layer manufacturing (ALM) technology because of the advantages they offer including design freedom, high precision, and the ability to produce parts directly from a numerical model. The macroscopic elastic and fatigue behaviours of these structures depend on several factors such as elementary cell (EC) topology, material and manufacturing process characteristics, as well as loading conditions. It is necessary to propose dedicated numerical approaches in order to investigate the influence of each factor on the macroscopic behaviour of the structure before manufacturing and experimental evaluation of the selected cell structure.

Objectives

Results

Conclusion