Reference : A quasicontinuum approach towards mechanical simulations of periodic lattice structures

	Document type :	Dissertations and theses : Doctoral thesis
	Discipline(s) :	Engineering, computing & technology : Mechanical engineering
	Focus Areas :	Computational Sciences
	To cite this reference:	http://hdl.handle.net/10993/46992

Title :	A quasicontinuum approach towards mechanical simulations of periodic lattice structures
Language :	English
Author, co-author :	Chen, Li [University of Luxembourg > Faculty of Science, Technology and Medicine (FSTM) > Department of Engineering (DoE) >]
Publication date :	16-Nov-2021
Institution :	University of Luxembourg, ​Esch-sur-Alzette, ​​Luxembourg
Name of the degree :	Docteur en Sciences de l'Ingénieur
Number of pages :	131
Supervisor :	Bordas, Stéphane
	Massart, Thierry
President of the jury :	Zilian, Andreas
Member of the jury :	Francois, Francois
	Ortiz, Michael
	Dendievel, Rémy
Keywords :	[en] quasicontinuum method ; periodic lattice structures ; mechanical simulation
Abstract :	[en] Thanks to the advancement of additive manufacturing, periodic metallic lattice structures are gaining more and more attention. A major attraction of them is that their design can be tailored to specific applications by changing the basic repetitive pattern of the lattice, called the unit cell. This may involve the selection of optimal strut diameters and orientations, as well as the connectivity and strut lengths. Numerical simulation plays a vital role in understanding the mechanical behavior of metallic lattices and it enables the optimization of design parameters. However, conventional numerical modeling strategies in which each strut is represented by one or more beam finite elements yield prohibitively time­consuming simulations for metallic lattices in engineering­scale applications. The reasons are that millions of struts are involved, as well as that geometrical and material nonlinearities at the strut level need to be incorporated. The aim of this thesis is the development of multi­scale quasicontinuum (QC) frameworks to substantially reduce the simulation time of nonlinear mechanical models of metallic lattices. For this purpose, this thesis generalizes the QC method by a multi­field interpolation enabling amongst others the representation of varying diameters in the struts’ axial directions (as a consequence of the manufacturing process). The efficiency is further increased by a new adaptive scheme that automatically adjusts the model reduction whilst controlling the (elastic or elastoplastic) model’s accuracy. The capabilities of the proposed methodology are demonstrated using numerical examples, such as indentation tests and scratch tests, in which the lattice is modeled using geometrically nonlinear elastic and elastoplastic beam finite elements. They show that the multi­scale framework combines a high accuracy with substantial model reduction that are out of reach of direct numerical simulations.
Research centres :	University of Luxembourg: Computational Sciences
Funders :	Fonds de la Recherche Scientifique Begium
Name of the research project :	Multiscale modelling of lightweight metallic materials accounting for variability of geometrical and material properties
Target :	Researchers ; Professionals ; Students
Permalink :	http://hdl.handle.net/10993/46992

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