PSI - Issue 5

Sven Nagel et al. / Procedia Structural Integrity 5 (2017) 1377–1384 Nagel, Knödel, Ummenhofer / Structural Integrity Procedia 00 (2017) 000 – 000

1380

4

Translatoric motion is applied by moving both jacks in the same direction simultaneously and pure torsion by moving them antimetric. Arbitrary combinations of torsion and bending are applied by different amplitudes and phases. The motion of the RP is not clearly defined by the two elongations of the jacks and therefore tracked by a DIC (DIC-global). Strains on the outer surface of the specimen in the area between the weld and the internal geometric notch, as explained in chapter 2.1, are measured by the help of a second DIC (DIC-local). 2.3. Test Matrix 96 of the 120 tested specimens are used for evaluation. The tests are classified in three major groups a) constant amplitudes, b) load paths and c) variable amplitudes. Each consists of several states as described below. a) Constant stress states and constant amplitudes (CA) Guided by pure bending (k  = 1) and pure torsion (k  = 0) four other load states in- between (termed “ratios”) have been tested. Two are dominated by bending, two by torsion. As the stress state is dominated by inelastic true strains up to 100 % these states were characterized by the strain relation k  defined in (1) . = + (1)

Figure 3: Test setup Tube-to-Plate

k  = 0

k  = 0.1

k  = 0.2

k  = 0.4 k  = 0.6

k  = 1

Figure 4: Qualitative load situations (see (1) )

In the cases of k  = 1 and k  = 0 several magnitudes were applied. These magnitudes were chosen in a way, that either bending or head rotation of a ratio can be linked with one of these basic cases. The counterpart was added to this deformation. The tests are summarized in Figure 4 and Table 2. Informations of the stress state an strain amplitudes determined in numerical simulations with “Mod 2” are added. Table 2: Test matrix CA Code k  B [mm] T [°] T L  pl /2 Code k  B [mm] T [°] T L  pl /2 B 70 1 70 0 0.58 0.05 77 R 1.1 0.6 70 11 0.56 0.2 25 B 50 1 50 0 0.58 0 47 R 1.2 0.4 50 11 0.19 0.5 30 B 30 1 30 0 0.56 0 14 R 2.1 0.2 30 30 0.52 0.4 13 T 40 0 0 40 0 0 103 R 2.2 0.1 20 43 0.09 0.2 87 T 49 0 0 49 0 0 130 b) Path loading (P) Four more complex scenarios termed as “path” were defined. These should cover realistic ear thquake loading. In these cases, key stress states, represented by dots in Figure 5, are approached along different paths. The limiting states of pure bending and pure torsion are achieved in P1, P3 and P4 by mixed states, in P2 this transition is done continuously. Other than P3 and P4 the loading in P1 and P2 has alternating signs. For P1 and P2 two different amplitudes have been tested . Path 1 Path 2 Path 3 Path 4

-30 -15 0 15 30 Torison [ ° ]

-30 -15 0 15 30

-30 -15 0 15 30

-30 -15 0 15 30

-75 -25 25 75 Bending [mm]

-75 -25 25 75 Bending [mm]

-75 -25 25 75

-75 -25 25 75 Bending [mm]

Bending [mm]

Figure 5: Overview of path loading with constant amplitudes