Strength and stiffness of 3D-printed connectors compared with the wooden mortise and tenon joints for chairs

ABSTRACT

In this study, 3D-printed connectors to replace the typical L-shaped joints in the construction of a chair were developed, tested and numerically analysed. Different connectors were designed and manufactured with a fused deposition modelling (FDM) 3D printer using acrylonitrile butadiene styrene (ABS) with the aim to find a simple shaped connector which could be used to build chairs and withstand standard chair loading requirements. The strength and stiffness of the joints were tested and compared with traditional beech mortise-and-tenon joints. Numerical stress and strain analyses were performed with the finite element method for an orthotropic linear-elastic model. The experimental results showed that joints with 3D-printed connectors achieved lower strength than the traditional wooden mortise-and-tenon joints with similar dimensions. The results indicate that the effect of reinforcement of the connector were not recognised due to the small thickness and inadequate geometric position and arrangement of the reinforcement ABS material. The chair assembled with 3D-printed connectors could withstand the loads for seating, but failed the backrest test according to standard EN 1728:2002. The connectors need to be optimised and reinforced to withstand standard loads.

KEYWORDS:

• Wood
• mortise-and-tenon joint
• 3D printing
• strength and stiffness

Acknowledgements

We also thank Erika Valentinčič for her enormous help in the laboratory and Ministry of Education, Science and Sport RS in the frame of the WoodWisdom-Net project W3BWood Believe.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by Ministrstvo za Izobraževanje, Znanost in Šport: [WoodWisdom-Net project W3B Wood Believe]; Slovenian Research Agency: [grant number P4-0015].