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20 - Newsletter EnginSoft Year 6 n°4
In summary, for an optimal solution, the constraints layout
should encompass the upper constraint going more close
with the opposite behavior for the lower constraints. In the
following picture the optimal solution is graphically
represented.
For the stresses, without having sufficient information about
the glass characteristics, it is more opportune to present the
deformation chart of the glass, during the pyrolysis phase.
5 Conclusions
The provided model is composed of an assembled system of
three glasses, mounted on a chassis that keeps them
separated to allow an air passage between them, in
accordance with the regulations for this appliance.
Experimental tests performed by Indesit are focused on
temperature measurement of pre-determined points located
on the internal side of the first glass, in pyrolysis conditions,
when the internal temperature of the oven rises to 500°C.
Punctual values of temperature, were computed with
response surface modeling in modeFRONTIER in order to
obtain a function that describes the temperature distribution
on the entire glass, and assigns a relative value on each FEM
model node.
The built map is related to the hot side of the considered
glass. To calculate temperature distribution on the cold side,
Picture 4.2.2 – Displacement sum
Picture 4.2.3 – Elongation due to the shear SXZ
the entire glass system was modeled by thermal analysis.
Knowing the internal cavity temperature distribution, the
safety temperature on the external side of the outdoor glass
and convex thermal coefficients, we were able to obtain the
temperature distribution on the coldest side of the most
stressed glass and hence also the thermal gradient applied to
this component.
The focus of the first simulation was on examining the free
constraint condition of the glass, or to verify the maximum
deformation of the glass, without constraint.
In the subsequent simulations, the initial configuration, as
described in the initial 3D model, was modeled with the dual
purpose to validate the FEM model with experimental results,
and to determine stress and deformation values of the initial
configuration.
The aim of the optimization process was to find an optimal
layout of the constraint system that minimizes stresses on
the internal glass. To achieve this result, the FEM model was
parametrized by means of a series of instructions named
“macros”, to allow modeFRONTIER to manage the geometry of
the model.
The task of modeFRONTIER is to modify the model geometry
on each run and to drive the input variables to the best set.
The modified parameters are referred to as the upper and
lower glass constraints dimension, and in particular, the
reciprocal distance and the width of each constraints are
verified.
The results were the values of stress and deformation on the
model, due to the thermal gradient applied. Due to
imperfections in the mesh, the mean value of stresses close
to constraints, was taken into account.
Obviously, the selected area for the calculation of this mean,
was related to the area affected by higher stress values, to
be precautionary.
The obtained results meet our expectations: a sensible
decrease of stresses was registered nearby 30-40% with
respect to the customer configuration, and a good
conversion of results was achieved, highlighting the good
quality of the work performed by modeFRONTIER.
The deformations of the optimized configuration are bigger
than the original ones, which is an indication that the
obtained design provides room for a better movement for the
glass.
Finally, we are certain that the obtained results are sufficient
and correct, and that this work has delivered further
information and details about the system behavior to the
modeFRONTIER users at Indesit Company.
For more information:
Ing. Nicola Baldecchi
info@enginsoft.it