Residual Strength and Fatigue Lifetime of ... - Solid Mechanics

H250 Specimen
H100 Specimen
H45 Specimen
z
y
x
50
480
Wood Wood insert
insert Release Teflon film film
Foam
Foam
core
core
Figure 5.2: Manufactured STT specimens and a drawing of STT specimens including
dimensions (mm).
At the centre of the specimens steel plates were glued to the top and bottom face sheets with
epoxy. Using the steel plates the top and bottom faces were fixed to the actuator of the testing
machine and the test rig respectively by four bolts. The test rig consists of welded steel profiles
of a wall thickness of 6 mm, see Figure 5.3. The wood reinforced ends of the specimens were
clamped to the test rig by square section steel profiles using four bolts. Furthermore, a 4 Mpix
Digital Image Correlation (DIC) measurement system (ARAMIS 4M) as shown in Figure 5.4
was used to monitor 2D surface strains to locate the crack tip continuously during the
experiments. The crack tip can be located by the strain concentration at the loaded crack tip,
which is visible in the DIC strain contours. Finally, a servo-hydraulic Instron actuator with a
maximum capacity of 100kN was used to load the STT specimens. However, a smaller 25 kN
load cell was mounted on the actuator to increase the accuracy of the load measurements, see
Figure 5.5.
92
1000
860
(Width 65mm)