8.2 Validation by experimental investigation
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specimens come closest to the idealized virtual tests. The comparison of virtual and experiment is illustrated in Figure 129.
Figure 129 Comparison of experimental with virtual test results; a) force-displacement curve and
b) weight specific force-displacement curve
When considering the force-displacement relationship, the virtual test matches the experiment accurately in case of the Reference. This is confirmed by the visual damage
progression. This agreement is reduced when considering the weight specific force-displacement curve. This can be explained by the difference between the estimated mass
of the virtual test specimen (22.0 g) and the determined weight of the physical specimen
(24.6 g). The weight estimation of the virtual test study is generally lower than the physical specimens (about 10%). Regarding the alternatives with increased potting radius, the
virtual tests indicate significantly higher peak forces if compared to the experiments. This
is expected due to undesired premature failure of the inserts, which is not represented
in the simulation. Therefore, the virtual tests cannot be fully validated in case of the
Hourglass and Undercut alternatives. However, the general curve progression trends of
virtual and physical tests are comparable for all considered designs. Hourglass and Undercut design present similar force-displacement curves with almost equal peak forces
in case of both, virtual and physical tests, while the Hourglass design indicates a better
performance when considering the weight specific force-displacement curve. In addition, it is assumed that without premature insert failure both alternatives would have
achieved higher peak forces, thus approaching the predictions from the virtual tests.
However, in sum the performed experimental study only enables a qualitative comparison with the virtual test results. A comprehensive validation based on test results without premature insert failure remains.
Reference Test
Reference Sim.
Hourglass Test
Hourglass Sim.
Undercut Test
Undercut Sim.
a)
b)
161
specimens come closest to the idealized virtual tests. The comparison of virtual and experiment is illustrated in Figure 129.
Figure 129 Comparison of experimental with virtual test results; a) force-displacement curve and
b) weight specific force-displacement curve
When considering the force-displacement relationship, the virtual test matches the experiment accurately in case of the Reference. This is confirmed by the visual damage
progression. This agreement is reduced when considering the weight specific force-displacement curve. This can be explained by the difference between the estimated mass
of the virtual test specimen (22.0 g) and the determined weight of the physical specimen
(24.6 g). The weight estimation of the virtual test study is generally lower than the physical specimens (about 10%). Regarding the alternatives with increased potting radius, the
virtual tests indicate significantly higher peak forces if compared to the experiments. This
is expected due to undesired premature failure of the inserts, which is not represented
in the simulation. Therefore, the virtual tests cannot be fully validated in case of the
Hourglass and Undercut alternatives. However, the general curve progression trends of
virtual and physical tests are comparable for all considered designs. Hourglass and Undercut design present similar force-displacement curves with almost equal peak forces
in case of both, virtual and physical tests, while the Hourglass design indicates a better
performance when considering the weight specific force-displacement curve. In addition, it is assumed that without premature insert failure both alternatives would have
achieved higher peak forces, thus approaching the predictions from the virtual tests.
However, in sum the performed experimental study only enables a qualitative comparison with the virtual test results. A comprehensive validation based on test results without premature insert failure remains.
Reference Test
Reference Sim.
Hourglass Test
Hourglass Sim.
Undercut Test
Undercut Sim.
a)
b)