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TECHNOLOGY 33
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contact behaviour, stress distribution and critical regions in Mladec, Czech Republic.
FDM-printed dovetail connectors. RePLA+ (recycled polylactic acid plus, an enhanced-grade
Despite this progress, the material-efficient design of FDM- recycled PLA material with improved mechanical properties
printed furniture connectors is still not sufficiently described. and printability) was selected as a material suitable for FDM
Most studies focus on a particular connector geometry, a processing and functional polymer connectors.
specific joint type, dimensional accuracy or selected printing In the FEM model, the fully printed regions of the connector,

parameters. including perimeter walls, top and bottom solid layers, bridges,
Less attention has been paid to the combined effect and full infill regions, were represented using a simplified
of perimeter count and infill density on rotational stiffness, isotropic linear-elastic material model.
maximum bending moment, material consumption and printing A density of 1,240 kg·mễ³ was adopted, consistent with
time. This is a practical gap that this study aims to address. published technical data for rPLA materials. A Young's modulus
Therefore, this study investigates FDM-printed dovetail of 3,520 MPa and Poisson's ratio of 0.33 were adopted as
connectors for wooden furniture corner joints. One recycled reference isotropic input parameters based on values reported
PLA-based filament material, three perimeter configurations, for printed PLA in the literature.
and three cubic infill densities were analysed. These elastic parameters were not experimentally calibrated

The experimental part evaluates the moment-rotation for the specific Filament PM RePLA+ used in the mechanical
response, maximum bending moment and rotational stiffness tests. The isotropic representation therefore constitutes a
of the joints, while the numerical part uses a homogenised modelling simplification and does not explicitly account for
shell-core FEM model to examine stress distribution, connector- process-dependent anisotropy associated with raster orientation,
wood contact pressure and critical load-transfer regions. interlayer bonding, void structure, cooling conditions, humidity,
The study specifically examines whether increasing infill temperature, or strain rate.
density or increasing the number of perimeters is more effective Accordingly, the FEM model was used to compare relative

for improving joint behaviour, and whether mechanically sufficient differences in load transfer, contact behaviour, and stress
connector configurations can be achieved with lower material localisation among connector configurations rather than to
consumption and shorter printing time. provide an exact prediction of the constitutive response of
FDM-printed RePLA+.
Materials and Methods Used in the Study The sparse cubic infill was not modelled explicitly but was
Beech wood (Fagus sylvatica L.) was used as the base represented by a homogenised material domain with effective
material for the wooden members of the corner joints because properties derived from the reference fully dense material and
of its common use in furniture structures and its favourable the nominal infill density.
mechanical properties.

In the FEM model, beech wood was defined as an orthotropic
material with local material coordinates assigned according Corporate Environments
to the anatomical directions, allowing stress components in
the wooden members to be evaluated with respect to the
grain direction.
The dovetail connectors were manufactured from commercially
available 1.75 mm Filament PM RePLA+ supplied by Plasty