Figure 1: Three Modes of Delamination Growth Mode I Mode II Mode III Figure 1: Three Modes of Delamination Growth

MMB (Mode I II) (c) DCB (Mode I) (a) ENF (Mode II) (b) P I + - II 4 MMB (Mode I II) (c) P DCB (Mode I) (a) P ENF (Mode II) (b) Figure 2: (a) Double Cantilevered Beam, (b) End-Notched Flexure, and (c) Mixed Mode Bending Tests

Crack front PIII (a) 2PIII (b) Figure 3: (a) Split Cantilevered Beam, and (b) Modified Split Cantilevered Beam Tests

Figure 4: ERR Distribution in the SCB Test

4 z x y T PII PI - P Crack tip End support with one side fixture III T PI - II Linear bearing Crack tip End support with one side fixture Edge delamination PII loading roller with one side fixture Load tab Load pins y x z PII 4 Figure 5: STB Test Schematic

Figure 6: STB Solid Model Test Frame PII Actuator Support Frame Load Tabs PIII Actuator End Support PII Loading Roller Load Frame Clevis Specimen Linear Bearing Figure 6: STB Solid Model

Figure 7: Photograph of STB Test Setup MTS (P I ) actuator P III actuator End support Linear bearing PI actuator II Figure 7: Photograph of STB Test Setup

Un-delaminated Region End Delamination Edge Delaminations Un-delaminated Region B= 25.4 mm 152 mm B 0 1 β Figure 8: Specimen Schematic Showing Edge Delaminations

Figure 9: Effect of Edge Delamination Length on Mode III ERR Distribution

Pin for pin-and-clevis Load Block Mode I carrying screw Pin for pin-and-clevis Spacer Tab Specimen Delaminated region Figure 10: Load Tab Design

Figure 11: Typical Mode III Loading Curve

Upper clevis to load frame actuator Load Block Partially Threaded Rod Pin Figure 12: Original Upper Clevis Design

Figure 13: Finite Element Model of STB Specimen

Figure 14: Mode I Repeated Loading Test

PIII All pins threaded into load tabs Lower Clevis Upper Clevis Load Tab Specimen PIII Linear Bearing Spacer Tab Radial bearing Pins All pins threaded into load tabs Pin head tight against thrust bearing Thrust bearing Pin shank fits inside thrust bearing Figure 15: Modified Upper Clevis Design