142
7 Virtual testing approach for sandwich panel joints
Out-of-plane tension
In case of out-of-plane tension, the requirements and application scenario for the virtual
test are defined analogous to the previous demonstration example. The intention is to
develop a virtual test which is capable to predict catastrophic failure at computation
times between 2-4h. The reference tests were video recorded and a section cut of the
specimens after testing was prepared and analyzed (Figure 111, left). The characteristic
force displacement curve progression has been studied and the identified damage mechanisms are assigned to the curve progression stages (Figure 111, right). In comparison
to the fully potted inserts, the partially potted curve is not characterized by further increasing load after initiation of core shear buckling (stage ②) as first damage mechanism. Instead, the load drops significantly shortly after core damage initiation (stage ③).
This is due to tensile failure of the core below the potting, which initiates catastrophic
failure accompanied by face sheet failure in in the post failure regime (stage ④). Therefore, there are only two relevant mechanical effects, core shear buckling and tensile core
failure.
Figure 111 Problem analysis for partially potted inserts under pull-out loading
Debonding of core
and face sheet
Tensile failure of core
Face sheet failure
Shear buckling
of cell walls
3
2
4
4
3
1
2
4
3
Partially potted
26 mm
ABS5035-A4
Delo
ABS1005-08078T
ABS 5047-07
PP-26-010
Out-ofplane
tension
In-plane
shear
Configuration
Loading 1
Loading 2
Figure 110 Investigated configuration and loading conditions for validation of virtual testing approach based on partially potted inserts
7 Virtual testing approach for sandwich panel joints
Out-of-plane tension
In case of out-of-plane tension, the requirements and application scenario for the virtual
test are defined analogous to the previous demonstration example. The intention is to
develop a virtual test which is capable to predict catastrophic failure at computation
times between 2-4h. The reference tests were video recorded and a section cut of the
specimens after testing was prepared and analyzed (Figure 111, left). The characteristic
force displacement curve progression has been studied and the identified damage mechanisms are assigned to the curve progression stages (Figure 111, right). In comparison
to the fully potted inserts, the partially potted curve is not characterized by further increasing load after initiation of core shear buckling (stage ②) as first damage mechanism. Instead, the load drops significantly shortly after core damage initiation (stage ③).
This is due to tensile failure of the core below the potting, which initiates catastrophic
failure accompanied by face sheet failure in in the post failure regime (stage ④). Therefore, there are only two relevant mechanical effects, core shear buckling and tensile core
failure.
Figure 111 Problem analysis for partially potted inserts under pull-out loading
Debonding of core
and face sheet
Tensile failure of core
Face sheet failure
Shear buckling
of cell walls
3
2
4
4
3
1
2
4
3
Partially potted
26 mm
ABS5035-A4
Delo
ABS1005-08078T
ABS 5047-07
PP-26-010
Out-ofplane
tension
In-plane
shear
Configuration
Loading 1
Loading 2
Figure 110 Investigated configuration and loading conditions for validation of virtual testing approach based on partially potted inserts