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9 Summary and outlook
and compression. An isotropic material behavior with different plastic hardening in tension and compression was determined and implemented in a suitable material model
with the experimental stress-strain data as tabular input.
On structural element level, various bonded sandwich panel configurations were investigated based on standardized flexural bending and in-plane shear tests. The performed
bending tests exhibited three failure modes, face sheet compressive rupture, local core
indentation and core shear failure. In the corresponding numerical study, the tests were
implemented as detailed meso-scale model and 3D-continuum model. Here, the material parameters from the previous constituent level could be validated, while both models agreed well with the test results. However, the 3D-continuum model generally
proved to be less accurate in particular in case of core shear failure. In the in-plane shear
tests, the shear plasticity and strength of the face sheets was experimentally determined
and subsequently implemented in the face sheet material model.
On sub-component level, fully and partially potted sandwich panel insert configurations
were tested under out-of-plane pull out and in-plane shear loading. In addition, a mortise and tenon corner joint was investigated under shear and bending. Based on the findings of the previous building blocks, these sub-components tests were implemented as
simulation models using a common virtual testing approach. Good agreement between
physical and virtual tests was achieved. The virtual testing approach encompasses experimental and numerical investigations on all three introduced complexity levels. It provides guidance on the general procedure within the complexity levels as well as on the
definition of a suitable level of detail for the investigated sub-component. The proposed
approach was described in detail using one of the sub-component tests as demonstration example. Lastly, the application of the approach was demonstrated based on the
development of a novel sandwich panel insert design.
The presented research could be extended in different areas. In the investigated subcomponent tests, debonding of face and core was not a decisive damage mechanism.
Therefore, it is not reflected in detail in the virtual testing approach. However, it is generally known as key aspect in sandwich construction and could be added in the future.
In addition, the consideration of uncertainties is a natural next step for the proposed
virtual testing approach. This would allow to predict the scatter of mechanical properties, which is important for airworthiness substantiation applications. Lastly, the successful implementation of detailed meso-scale honeycomb models on sub-component level
paved the way for optimization studies, where the core is locally adapted for mechanically efficient load introduction. In combination with the design freedom of additive
manufacturing, novel adaptive core geometries could be developed with the help of the
established approach.
9 Summary and outlook
and compression. An isotropic material behavior with different plastic hardening in tension and compression was determined and implemented in a suitable material model
with the experimental stress-strain data as tabular input.
On structural element level, various bonded sandwich panel configurations were investigated based on standardized flexural bending and in-plane shear tests. The performed
bending tests exhibited three failure modes, face sheet compressive rupture, local core
indentation and core shear failure. In the corresponding numerical study, the tests were
implemented as detailed meso-scale model and 3D-continuum model. Here, the material parameters from the previous constituent level could be validated, while both models agreed well with the test results. However, the 3D-continuum model generally
proved to be less accurate in particular in case of core shear failure. In the in-plane shear
tests, the shear plasticity and strength of the face sheets was experimentally determined
and subsequently implemented in the face sheet material model.
On sub-component level, fully and partially potted sandwich panel insert configurations
were tested under out-of-plane pull out and in-plane shear loading. In addition, a mortise and tenon corner joint was investigated under shear and bending. Based on the findings of the previous building blocks, these sub-components tests were implemented as
simulation models using a common virtual testing approach. Good agreement between
physical and virtual tests was achieved. The virtual testing approach encompasses experimental and numerical investigations on all three introduced complexity levels. It provides guidance on the general procedure within the complexity levels as well as on the
definition of a suitable level of detail for the investigated sub-component. The proposed
approach was described in detail using one of the sub-component tests as demonstration example. Lastly, the application of the approach was demonstrated based on the
development of a novel sandwich panel insert design.
The presented research could be extended in different areas. In the investigated subcomponent tests, debonding of face and core was not a decisive damage mechanism.
Therefore, it is not reflected in detail in the virtual testing approach. However, it is generally known as key aspect in sandwich construction and could be added in the future.
In addition, the consideration of uncertainties is a natural next step for the proposed
virtual testing approach. This would allow to predict the scatter of mechanical properties, which is important for airworthiness substantiation applications. Lastly, the successful implementation of detailed meso-scale honeycomb models on sub-component level
paved the way for optimization studies, where the core is locally adapted for mechanically efficient load introduction. In combination with the design freedom of additive
manufacturing, novel adaptive core geometries could be developed with the help of the
established approach.