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TECHNOLOGY 39
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For connectors with five perimeters (5P), no visible connector with both increasing infill density and perimeter count. The
damage was observed; damage was mainly concentrated shortest printing time was recorded for configuration 1P20
in the wooden members and was characterised by splitting (406 s), whereas the longest printing time was observed for
along the grain. configuration 5P40 (561 s).
For the stress-based damage evaluation, the 30 percent However, this increase was not accompanied by a
infill configurations (1P30, 3P30, and 5P30) were selected proportional improvement in mechanical performance. The 5P

in order to isolate the effect of perimeter count on stress configurations and the variants with 40 percent infill required
distribution and damage localisation. longer printing times and higher material consumption, but did
The 30 percent infill level was used as a representative not achieve a corresponding increase in maximum bending
reference level because the experimental results and FEM moment or rotational stiffness.
contact results indicated that it provided a favourable balance In contrast, configuration 3P30 achieved the highest
between mechanical response and material consumption. rotational stiffness and the highest maximum bending moment
In the FDM-printed connector, equivalent von Mises stress with a printing time of 469 s, which was substantially shorter
was evaluated. The highest stress concentrations occurred than those of configurations 5P30 and 5P40.
primarily in the connector neck region, where an abrupt change Configuration 3P20 achieved the highest specific maximum

in cross-section and dovetail geometry is present. bending moment with a printing time of 444 s. Considering the
The maximum von Mises stress reached 68.32 MPa for combination of mechanical performance, material consumption,
configuration 1P30, 65.00 MPa for 3P30, and 87.03 MPa and production time, configurations 3P20 and 3P30 can be
for 5P30. considered the most favourable solutions.
These local stress maxima were within the range of typical
strength values reported for PLA-based materials. Therefore, Practical Implications for Furniture Manufacturing
these regions were interpreted as potentially critical locations The most important finding of this study is that maximum

within the connector rather than as a precise prediction of bending moment is governed primarily by perimeter count
failure initiation. (outer shell thickness), whereas infill density within the 20–40
The lowest stress level was observed for configuration percent range has no statistically significant effect.
3P30, indicating a slightly more favourable load distribution This means that for FDM-printed furniture connectors, the
within the polymer connector, particularly compared with outer walls carry the majority of the load, while the internal infill
configuration 5P30. contributes little to strength but significantly affects material
In the wooden members, normal stresses in the wood did consumption and printing time.
not exceed the reference tensile or compressive strengths
parallel to the grain. PICRYL

In contrast, shear stresses in the wood exceeded the
reference shear strength parallel to the grain for all evaluated
configurations. Therefore, the observed damage in the vicinity
of the slot was associated mainly with localised shear loading,
accompanied by indentation of the wood at the connector
bearing regions.
The net printing time of a single connector increased