Level 2 tests (specimen level) have been designed to obtain a real characterization of those failure modes which are more likely to occur during Level 3 test (subcomponent level), according to results obtained from WP1 tasks.
Four different types of Level 2 tests have been performed from May to October 2022:
1. CAI Test. The objective of this test is to obtain a Damage Tolerance Allowable (DTA), since the presence of a damage on subcomponent to be tested is considered on Level 3 test. Calibration and proper tests have been performed according to standard UNE 6038:2015 for the 3 different stacking configurations existing in Level 3 component (skin, omega and skin+omega). Ten specimens per configuration have been tested.
2. Unfolding test. The objective of this test is to obtain an Allowable value associated to Unfolding failure mode, which can occur in both upper and lower omega radius. Tests have been performed according to standard ASTM D6415/D6415-06a for 6 specimens with omega stringer stacking configuration.
3. Fracture Toughness Test Mode I (GIC). The objective of this test is to obtain value of Fracture Toughness in Mode I (crack opening under tensile stress). Failure due to crack opening in MODE I can occur at the interface between omega foot and skin Surface. GIC tests have been performed according to standard ASTM D5528-13 for 6 specimens with skin+omega stacking configuration.
4. Seven Point Bending (SPB) test. The objective of this test is to analyze the behavior of an omega-stiffened panel with bending about 2 perpendicular directions. Tooling was designed by ALESTIS allowing to modify location of reacting and load introduction supports in order to induce the required load state for 2 tested configurations: symmetric and antisymmetric. No standard is available for this test so it is based on info extracted from scientific research papers. Three tests per configuration (symmetric and antisymmetric) have been performed using flat omega-stiffened panel specimens.