198
Appendix C – Sub-component level
C3 Experimental results in novel design study
The following graph summarizes the experimental results of all tested specimens in the
framework of the novel insert design study. There is significant scatter in particular in
case of the reinforced configurations (Hourglass and Undercut). This scatter is evaluated
based on visual inspection of the specimens after testing. This evaluation is summarized
in the table on the following page.
Despite the noticeable scatter in terms of force-displacement relationship, the reference
configurations are characterized by consistent failure. Therefore, it is assumed that the
scatter is simply due to uncertainties of the material especially regarding the bonding.
All three hourglass configurations present a different failure mode, while each specimen
failed prematurely. Hourglass_01 and _03 have a similar curve progression, while specimen 01 failed due to screw shear off and specimen 03 due to insert rupture. Specimen
02 is an outlier, which failed due to debonding of insert and adhesive. This was caused
by the Spax screw which pierced through the insert penetrating the adhesive, thus leading to an initial crack between insert and adhesive.
The undercut configurations are characterized by the most significant scatter. This is due
to poor and inconsistent manufacturing in particular in terms of removing the core for
the undercut cavity. A lack of specialized tools made this manufacturing step difficult.
This results in considerably varying potting conditions. Only specimen Undercut_03 can
be considered close to the desired Undercut potting condition. This is also evident in the
force displacement relationship, which develop the characteristic curve progression only
in case of specimen 03. However, catastrophic failure is here also caused by insert rupture analogous to the hourglass configurations. The remaining Undercut specimens can
be considered outliers due to poor manufacturing. For comparison with the virtual tests,
a single characteristic curve for each configuration is selected (gray highlights in following table).
0
2
4
6
0
500
1000
1500
2000
2500
3000
Displacement [mm]
Force [N]
Reference_01
Reference_02
Reference_03
Hourglass_01
Hourglass_02
Hourglass_03
Undercut_01
Undercut_02
Undercut_03
Appendix C – Sub-component level
C3 Experimental results in novel design study
The following graph summarizes the experimental results of all tested specimens in the
framework of the novel insert design study. There is significant scatter in particular in
case of the reinforced configurations (Hourglass and Undercut). This scatter is evaluated
based on visual inspection of the specimens after testing. This evaluation is summarized
in the table on the following page.
Despite the noticeable scatter in terms of force-displacement relationship, the reference
configurations are characterized by consistent failure. Therefore, it is assumed that the
scatter is simply due to uncertainties of the material especially regarding the bonding.
All three hourglass configurations present a different failure mode, while each specimen
failed prematurely. Hourglass_01 and _03 have a similar curve progression, while specimen 01 failed due to screw shear off and specimen 03 due to insert rupture. Specimen
02 is an outlier, which failed due to debonding of insert and adhesive. This was caused
by the Spax screw which pierced through the insert penetrating the adhesive, thus leading to an initial crack between insert and adhesive.
The undercut configurations are characterized by the most significant scatter. This is due
to poor and inconsistent manufacturing in particular in terms of removing the core for
the undercut cavity. A lack of specialized tools made this manufacturing step difficult.
This results in considerably varying potting conditions. Only specimen Undercut_03 can
be considered close to the desired Undercut potting condition. This is also evident in the
force displacement relationship, which develop the characteristic curve progression only
in case of specimen 03. However, catastrophic failure is here also caused by insert rupture analogous to the hourglass configurations. The remaining Undercut specimens can
be considered outliers due to poor manufacturing. For comparison with the virtual tests,
a single characteristic curve for each configuration is selected (gray highlights in following table).
0
2
4
6
0
500
1000
1500
2000
2500
3000
Displacement [mm]
Force [N]
Reference_01
Reference_02
Reference_03
Hourglass_01
Hourglass_02
Hourglass_03
Undercut_01
Undercut_02
Undercut_03