Page 51 - FDMAsia NovDec 2024

MATERIALS 49
www.fdmasia.com | FDM ASIA NOV/DEC 2024

Bucharest. the identification of the plastic zones in the sample, the
First of all, the fundamental characteristics of wood in deformation of the proposed glued laminated timber sample
the form of glued laminated timber can be seen with some can be seen “formation of the plastic zones of tangents in
dimensions of elements, the types of forces applied on the the sample” and “deformation of the model”.

elements (traction and compression parallel with the fibres The model with the same parameters and characterisations
and bending) and the average value of the strength results. as the wooden sample subjected to deformations by the Finite
Ten samples for each test were performed. Element Method can be compared directly with the samples
Secondly, 20 samples of glued laminated timber elements subjected to loadings in the shearing box.
with dimensions 60 × 60 mm × 20 mm were inserted into a It can be seen in the two images “deformation of the
shear box where force was applied on them until breaking point. model” and “the real wooden sample” that the pattern follows
In “the force applied on the wooden sample in the shear box”, the same distribution of the deflection.
the shearing box can be observed, with specific dimensions Strain compatibility was monitored by recording the strain
in which the wood sample can be inserted perfectly with history at a point belonging to the failure surface. Comparing these

the force being applied on the centre of the piece following. results with those obtained from the laboratory determination,
After the breaking point, the sample is retrieved and in “the it can be seen that the mobilisation of deformations occurs
wooden sample after the application of the force” and “the in a similar way.
broken sample”, the breaking pattern is visible. The wooden
piece has been broken completely. Model And Methods
The experimental campaign was carried out following some Following the steps described above, a database was created
test steps that were needed in order to verify the correctness with optimised models obtained by generating, following Monte-

of the results considering the correlation between the Mohr– Carlo simulation principle multiple models that are created by
Coulomb parameters and the unitary forces. using scripts for the automation of FEM runs.
In order to verify the mechanical parameters obtained, The general characterisation of the samples considered for
elasto-plastic modelling was performed in explicit dynamics the FEM model can be seen in “three-dimensional compute
formulations in order to be able to follow the evolution of the assembly”. The dimensions of the elements are 10,000 mm
deformations over time. The geometry of the element takes into × 160 mm × 40 mm with two fixed supports of 600 mm ×
consideration the restrictions of the model in the experimental
campaign due to the dimensions of the shear box. Shutterstock
The model created consisted of replicating the sample

used in the direct shearing machine with the parallelepiped
sample dimensions mentioned above.
The shear plan was determined midway through the test,
based on the boundary conditions. The load was applied by
a certain imposed deformation, with constant speed. The
colour map represents the sensitivity of parts of the wooden
elements when force is applied.

The deformation model using the parameters defined
beforehand can be identified in “the model created”. After