Analysis of a Preliminary Design Approach for Conformal Lattice Structures

Pierandrea Dal Fabbro,Gianmaria Concheri,Roberto Meneghello,Diego Boscolo Bozza,Alessandro Ceruti,Gianpaolo Savio,Stefano Rosso

doi:10.3390/app112311449

Pierandrea Dal Fabbro, Gianmaria Concheri + Show 5 more

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https://doi.org/10.3390/app112311449

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Abstract

An important issue when designing conformal lattice structures is the geometric modeling and prediction of mechanical properties. This paper presents suitable methods for obtaining optimized conformal lattice structures and validating them without the need for high computational power and time, enabling the designer to have quick feedback in the first design phases. A wireframe modeling method based on non-uniform rational basis spline (NURBS) free-form deformation (FFD) that allows conforming a regular lattice structure inside a design space is presented. Next, a previously proposed size optimization method is adopted for optimizing the cross-sections of lattice structures. Finally, two different commercial finite element software are involved for the validation of the results, based on Euler–Bernoulli and Timoshenko beam theories. The findings highlight the adaptability of the NURBS-FFD modeling approach and the reliability of the size optimization method, especially in stretching-dominated cell topologies and load conditions. At the same time, the limitation of the structural beam analysis when dealing with thick beams is noted. Moreover, the behavior of different kinds of lattices was investigated.

Highlights

Nowadays, the development of additive manufacturing (AM) technologies increases the freedom in the production of parts with a complex shape, enabling the designer to overcome the limitations imposed by traditional manufacturing technologies
The developed method allows designing conformal lattice structures based on the non-uniform rational basis spline (NURBS)-free-form deformation (FFD) approach and performing size optimization
The method allows obtaining wireframe lattice structures that conform to the boundaries in the same environment but, as a drawback, it can be complicated to reach the aimed deformation of the captive parts depending on the number of control points; more, in Rhinoceros software, the NURBS-FFD control volume is rectangular or cubical leading to a trial-and-error approach when moving the points to follow the external shape of the object

Summary

Introduction

The development of additive manufacturing (AM) technologies increases the freedom in the production of parts with a complex shape, enabling the designer to overcome the limitations imposed by traditional manufacturing technologies. Some material distribution strategies mimic the mineral structures and the animals’ skeletons They are called cellular structures and are obtained by the arrangement and the repetition of a unit cell in the space [3]. Lattice structures present interesting properties: lightweight, high strength, energy absorption, and vibration reduction [4,5,6,7,8]. These properties are directly related to the structure shape, the cell topology, the cell dimension, and the cell element size. A few studies are available in the literature regarding this kind of lattices [15,16], and effective design methods are needed

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