SAMPE Journal - September/October 2016 - 12
Feature Article
Figure 18. 40J OML impact
on stringer CL, max 40 mm
butt joint damage.
Figure 19. 10J IML impact in
grid corner; 60 mm butt joint
damage, no visible dent.
Figure 20. 10 J IML impact at
corner with improved butt joint
compound: no visible dent and
no butt joint damage.
Figure 17. Falling weight impact test set up, panel supported
on the frames for impacts on the outside of the panel (OML).
indeed gave 60 mm butt joint damage in the longitudinal
stringer at a low energy level (10J, Figure 19).
However, in second generation panels, an improved
butt joint compound was used with a significantly
improved peel strength. In these panels the impact at the
corner did not result in butt joint cracks due to impact
(Figure 20 and 21).
It can be concluded that the BVID impact behavior
of the orthogrid panel with the improved butt joint
compound is quite acceptable.
Panel Compression Tests
To further evaluate the orthogrid panel, compression
tests were carried out. Four panels were manufactured
and tested in both pristine and damaged condition.
Figure 22 shows a pristine thin compression panel a
few kN before final failure. The skin pockets are buckled
and one of the stringer caps is fractured due to exceeded
material strength related to in plane bending of the cap.
Both in the thin and thick pristine panel, the fracture
of the cap was the initiation of stringer failure and final
failure of the panel. Note that this failure mode is not
related to the fact that butt joints are used in the stringer.
Figure 23 shows the opening of an artificial butt joint
crack during a compression test on a thin damaged
panel. In this panel 110mm artificial butt joint crack was
applied before the test to study the effect of a stringer
disbond. Especially whether or not the butt joint would
rupture due to the opening of the crack was of interest.
This was not the case however. In both the thick and
thin damaged panel, the panel final failure was again
initiated by stringer material strength failure and not by
butt joint rupture at the artificial crack. This conclusion
was derived from high speed camera footage.
It can be concluded that the butt joint in the tested
orthogrid compression panels is not the critical element,
12
Figure 21. 16J IML impact at
corner with improved butt joint
compound, clearly visible dent
(hole) and no butt joint damage.
Figure 22. Pristine thin 8 ply panel loaded in compression, a
few kN before final failure.
SAMPE Journal, Volume 52, No. 5, September/October 2016
Table of Contents for the Digital Edition of SAMPE Journal - September/October 2016
Contents
SAMPE Journal - September/October 2016 - Cover1
SAMPE Journal - September/October 2016 - Cover2
SAMPE Journal - September/October 2016 - Contents
SAMPE Journal - September/October 2016 - 2
SAMPE Journal - September/October 2016 - 3
SAMPE Journal - September/October 2016 - 4
SAMPE Journal - September/October 2016 - 5
SAMPE Journal - September/October 2016 - 6
SAMPE Journal - September/October 2016 - 7
SAMPE Journal - September/October 2016 - 8
SAMPE Journal - September/October 2016 - 9
SAMPE Journal - September/October 2016 - 10
SAMPE Journal - September/October 2016 - 11
SAMPE Journal - September/October 2016 - 12
SAMPE Journal - September/October 2016 - 13
SAMPE Journal - September/October 2016 - 14
SAMPE Journal - September/October 2016 - 15
SAMPE Journal - September/October 2016 - 16
SAMPE Journal - September/October 2016 - 17
SAMPE Journal - September/October 2016 - 18
SAMPE Journal - September/October 2016 - 19
SAMPE Journal - September/October 2016 - 20
SAMPE Journal - September/October 2016 - 21
SAMPE Journal - September/October 2016 - 22
SAMPE Journal - September/October 2016 - 23
SAMPE Journal - September/October 2016 - 24
SAMPE Journal - September/October 2016 - 25
SAMPE Journal - September/October 2016 - 26
SAMPE Journal - September/October 2016 - 27
SAMPE Journal - September/October 2016 - 28
SAMPE Journal - September/October 2016 - 29
SAMPE Journal - September/October 2016 - 30
SAMPE Journal - September/October 2016 - 31
SAMPE Journal - September/October 2016 - 32
SAMPE Journal - September/October 2016 - 33
SAMPE Journal - September/October 2016 - 34
SAMPE Journal - September/October 2016 - 35
SAMPE Journal - September/October 2016 - 36
SAMPE Journal - September/October 2016 - 37
SAMPE Journal - September/October 2016 - 38
SAMPE Journal - September/October 2016 - 39
SAMPE Journal - September/October 2016 - 40
SAMPE Journal - September/October 2016 - 41
SAMPE Journal - September/October 2016 - 42
SAMPE Journal - September/October 2016 - 43
SAMPE Journal - September/October 2016 - 44
SAMPE Journal - September/October 2016 - 45
SAMPE Journal - September/October 2016 - 46
SAMPE Journal - September/October 2016 - 47
SAMPE Journal - September/October 2016 - 48
SAMPE Journal - September/October 2016 - 49
SAMPE Journal - September/October 2016 - 50
SAMPE Journal - September/October 2016 - 51
SAMPE Journal - September/October 2016 - 52
SAMPE Journal - September/October 2016 - 53
SAMPE Journal - September/October 2016 - 54
SAMPE Journal - September/October 2016 - 55
SAMPE Journal - September/October 2016 - 56
SAMPE Journal - September/October 2016 - 57
SAMPE Journal - September/October 2016 - 58
SAMPE Journal - September/October 2016 - 59
SAMPE Journal - September/October 2016 - 60
SAMPE Journal - September/October 2016 - 61
SAMPE Journal - September/October 2016 - 62
SAMPE Journal - September/October 2016 - 63
SAMPE Journal - September/October 2016 - 64
SAMPE Journal - September/October 2016 - 65
SAMPE Journal - September/October 2016 - 66
SAMPE Journal - September/October 2016 - 67
SAMPE Journal - September/October 2016 - 68
SAMPE Journal - September/October 2016 - 69
SAMPE Journal - September/October 2016 - 70
SAMPE Journal - September/October 2016 - 71
SAMPE Journal - September/October 2016 - 72
SAMPE Journal - September/October 2016 - 73
SAMPE Journal - September/October 2016 - 74
SAMPE Journal - September/October 2016 - 75
SAMPE Journal - September/October 2016 - 76
SAMPE Journal - September/October 2016 - 77
SAMPE Journal - September/October 2016 - 78
SAMPE Journal - September/October 2016 - 79
SAMPE Journal - September/October 2016 - 80
SAMPE Journal - September/October 2016 - 81
SAMPE Journal - September/October 2016 - 82
SAMPE Journal - September/October 2016 - 83
SAMPE Journal - September/October 2016 - 84
SAMPE Journal - September/October 2016 - 85
SAMPE Journal - September/October 2016 - 86
SAMPE Journal - September/October 2016 - 87
SAMPE Journal - September/October 2016 - 88
SAMPE Journal - September/October 2016 - 89
SAMPE Journal - September/October 2016 - 90
SAMPE Journal - September/October 2016 - 91
SAMPE Journal - September/October 2016 - 92
SAMPE Journal - September/October 2016 - 93
SAMPE Journal - September/October 2016 - 94
SAMPE Journal - September/October 2016 - 95
SAMPE Journal - September/October 2016 - 96
SAMPE Journal - September/October 2016 - 97
SAMPE Journal - September/October 2016 - 98
SAMPE Journal - September/October 2016 - 99
SAMPE Journal - September/October 2016 - 100
SAMPE Journal - September/October 2016 - 101
SAMPE Journal - September/October 2016 - 102
SAMPE Journal - September/October 2016 - 103
SAMPE Journal - September/October 2016 - 104
SAMPE Journal - September/October 2016 - 105
SAMPE Journal - September/October 2016 - 106
SAMPE Journal - September/October 2016 - 107
SAMPE Journal - September/October 2016 - 108
SAMPE Journal - September/October 2016 - 109
SAMPE Journal - September/October 2016 - 110
SAMPE Journal - September/October 2016 - 111
SAMPE Journal - September/October 2016 - 112
SAMPE Journal - September/October 2016 - 113
SAMPE Journal - September/October 2016 - 114
SAMPE Journal - September/October 2016 - 115
SAMPE Journal - September/October 2016 - 116
SAMPE Journal - September/October 2016 - 117
SAMPE Journal - September/October 2016 - 118
SAMPE Journal - September/October 2016 - 119
SAMPE Journal - September/October 2016 - 120
SAMPE Journal - September/October 2016 - Cover3
SAMPE Journal - September/October 2016 - Cover4
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