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Tensile strength of partially filled FFF printed parts: meta modelling

Lookup NU author(s): Shahrain Mahmood, Dr Ahmed Qureshi, Dr Kheng-Lim GohORCiD, Dr Didier Talamona

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Abstract

Purpose – This paper aims to investigate the tensile strength of partially filled fused filament fabrication (FFF) printed parts with respect of cross-sectional geometry of partially filled test pieces. It was reported in the authors’ earlier work that the ultimate tensile strength (UTS) is inversely proportional to the cross-sectional area of a specimen, whereas the number of shells and infill density are directly proportional to the UTS with all other parameters being held constant. Here, the authors present an in-depth evaluation of the phenomenon and a parametric model that can provide useful estimates of the UTS of the printed part by accounting for the dimensions of the solid floor/roof layers, shells and infills. Design/methodology/approach – It was found that partially filled FFF printed parts consist of hollow sections. Because of these voids, the conventional method of determining the UTS via the gross cross-sectional area given by A b h, where b and h are the width and thickness of the printed part, respectively, cannot be used. A mathematical model of a more accurate representation of the cross-sectional area of a partially filled part was formulated. Additionally, the model was extended to predict the dimensions as well as the lateral distortion of the respective features within a printed part using input values from the experimental data. Findings – The result from this investigation shows that to calculate the UTS of a partially filled FFF part, the calculation based on the conventional approach is not sufficient. A new meta-model is proposed which takes into account the geometry of the internal features to give an estimate of the strength of a partially filled printed part that is closer to the value of the strength of the material that is used for fabricating the part. Originality/value – This paper investigates the tensile strength of a partially filled FFF printed part. The results have shown that the tensile strength of a partially filled part can be similar to that of a solid part, at a lower cost: shorter printing time and lower material usage. By taking into account the geometries within a printed part, the cross-sectional area can be accurately represented. The mathematical model which was developed would aid end-users to predict the tensile strength for a given set of input values of the process parameters.

Publication metadata

Author(s): Mahmood S, Qureshi AJ, Goh KL, Talamona D

Publication type: Article

Publication status: Published

Journal: Rapid Prototyping Journal

Year: 2017

Volume: 23

Issue: 3

Pages: 524-533

Online publication date: 13/03/2017

Acceptance date: 08/07/2016

ISSN (print): 1355-2546

ISSN (electronic): 1758-7670

Publisher: Emerald Publishing Limited

URL: https://doi.org/10.1108/RPJ-10-2015-0151

DOI: 10.1108/RPJ-10-2015-0151

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