PSI - Issue 42

K. Koch et al. / Procedia Structural Integrity 42 (2022) 506–512

509

4

Author name / Structural Integrity Procedia 00 (2019) 000 – 000 = 2 (1 − 2 ) + 1.9 pl N ( − 0 ) · ( 2( 1 − − 0 ) )

(1)

3. Results and discussion It could be observed that the load line displacement of the support increases with an increasing force. After force release, a part of the displacement remains, which is then dissipated over time by low-frequency vibrations of the support, see Fig. 2a. This can be attributed to a part of the impact energy being absorbed by the support and converted into elastic strain energy. The area under the force-displacement curve corresponds to the dissipated energy, see Fig. 2b. The compliance of the support can be calculated from the slope of the force-displacement curve. It can be specified as approximately 4 µm/kN and is neither affected by the impact energy nor the specimen material. This compliance can be used to correct the displacement measurement.

100 120

a)

b)

10 12 14 16

10 12

Force

Displacement

EN-GJS-400-18 a 0 / W = 0.2 E 0 = 5 J

20 40 60 80

0 2 4 6 8

42CrMo4 a 0 / W = 0.2 E 0 = 3 J

0 2 4 6 8

0.60 J

42CrMo4 a 0 / W = 0.2 E 0 = 5 J

Force [kN]

Force [kN]

-40 -20 0

0.25 J

-4 -2

detachment of the tup

Support displacement [µm]

0

5

10 15 20 25

0

25

50

75

100

125

Time [ms]

Support displacement [µm]

Fig. 2. Behavior of the support in elastic tests, (a) vibrations after force release, (b) force-displacement-curves for both materials.

Similarly, effects on the tup and specimen were examined, see Fig. 3a. The remaining displacement after force release can be explained by local plastic deformations on the specimen. These occur due to the Hertzian contact between the specimen and the tup. A part of the impact energy is absorbed by the specimen and converted into plastic deformation energy. In the case of nodular cast iron, it should be noted that damage at the notch or the crack tip can occur even at low loads. This can be attributed to delamination of the graphite particles from the matrix. In this case, the tests cannot be regarded as purely elastic. The comparison of the two materials should be evaluated critically. Energy losses due to elastic deformations and vibrations of the tup are negligible for the investigated impact energies.

100 200 300 400 500 600 Velocity [mm/s] b)

10 12 14

a)

42CrMo4 a 0 / W = 0.2 E 0 = 3 J

EN-GJS-400-18 a 0 / W = 0.2 E 0 = 3 J

42CrMo4 a 0 / W = 0.2 E 0 = 3 J

0 2 4 6 8

Force [kN]

0,13 J

0,71 J

EN-GJS-400-18 a 0 / W = 0 E 0 = 2 J

0 200 400 600 800 1000 1200 1400 -100 0

0

100

200

300

400

Tup displacement [µm]

Time [ms]

Fig. 3. Behavior of the tup and specimen in elastic tests, (a) force-displacement-curves for both materials, (b) specimen vibrations after the test.