5 Mechanical characterization on structural element
level
In sandwich construction, the structural element level coincides with the bonded sandwich panel, which represents the combination of the two main constituents, face sheet
and core. It is generally assumed that the material properties and modelling approaches,
which are derived on constituent level, enable to predict the material behavior on structural element level. The investigations within this second building block were firstly intended to validate this assumption. In addition, the objective was to consider additional
relevant aspects that can only be investigated on structural element level. Furthermore,
as it is shown in chapter 4, the material properties of the face sheets are degraded due
to the core bonding process. Therefore, investigations on structural element level serve
as primary source for face sheet properties, which include this degradation. In the framework of the present thesis, two structural element test setups are investigated in experimental and numerical studies. This is described in the following.
5.1 Panel flexure
In bending or flexural tests, beams are typically subjected to flatwise flexure. In sandwich
construction, bending is probably the most important test on structural element level
and numerous comprehensive studies on the flexural behavior of honeycomb sandwich
panels are available. This is because flexural tests can cover a variety of key material
properties. Due to the mechanical working principle of sandwich beams, bending tests
are not only applied to determine or validate the flexural stiffness of the sandwich construction but also the shear modulus and strength of the core as well as face sheet modulus and strength [Zen97]. In addition, bending tests may also indicate failure of the face
to core bond as well as core compression due to local indentation. Due to the numerous
failure mechanisms, failure mode maps are commonly applied to predict the failure
mode of bending test setups [Dan02], [Pet99], [Zin10], [Oth08], [Bel09]. In the present
work, an extensive joint experimental and numerical study on sandwich bending was
© Springer-Verlag GmbH Germany, part of Springer Nature 2020
R. Seemann, A Virtual Testing Approach for Honeycomb Sandwich Panel
Joints in Aircraft Interior, Produktentwicklung und Konstruktionstechnik 16,
https://doi.org/10.1007/978-3-662-60276-8_5
level
In sandwich construction, the structural element level coincides with the bonded sandwich panel, which represents the combination of the two main constituents, face sheet
and core. It is generally assumed that the material properties and modelling approaches,
which are derived on constituent level, enable to predict the material behavior on structural element level. The investigations within this second building block were firstly intended to validate this assumption. In addition, the objective was to consider additional
relevant aspects that can only be investigated on structural element level. Furthermore,
as it is shown in chapter 4, the material properties of the face sheets are degraded due
to the core bonding process. Therefore, investigations on structural element level serve
as primary source for face sheet properties, which include this degradation. In the framework of the present thesis, two structural element test setups are investigated in experimental and numerical studies. This is described in the following.
5.1 Panel flexure
In bending or flexural tests, beams are typically subjected to flatwise flexure. In sandwich
construction, bending is probably the most important test on structural element level
and numerous comprehensive studies on the flexural behavior of honeycomb sandwich
panels are available. This is because flexural tests can cover a variety of key material
properties. Due to the mechanical working principle of sandwich beams, bending tests
are not only applied to determine or validate the flexural stiffness of the sandwich construction but also the shear modulus and strength of the core as well as face sheet modulus and strength [Zen97]. In addition, bending tests may also indicate failure of the face
to core bond as well as core compression due to local indentation. Due to the numerous
failure mechanisms, failure mode maps are commonly applied to predict the failure
mode of bending test setups [Dan02], [Pet99], [Zin10], [Oth08], [Bel09]. In the present
work, an extensive joint experimental and numerical study on sandwich bending was
© Springer-Verlag GmbH Germany, part of Springer Nature 2020
R. Seemann, A Virtual Testing Approach for Honeycomb Sandwich Panel
Joints in Aircraft Interior, Produktentwicklung und Konstruktionstechnik 16,
https://doi.org/10.1007/978-3-662-60276-8_5