MIL-HDBK-17-3F Volume 3.Foreword Table of Contents 7.8.4.1.3 LEFM-based methods. .109 7.8.4.1.4R-curves...... .110 7.8.4.2 Single delaminations and disbonds.......................113 7.8.4.2.1 Fracture mechanics approaches.. ..114 7.8.4.2.2 Sublaminate buckling methods114 7.8.4.3 Impact damages..115 7.8.4.3.1 Sublaminate buckling methods...... ..115 7.8.4.3.2 Strain softening methods...119 7.8.4.4 Cuts and gouges...... 121 79 APPLICATIONS/EXAMPLES.........121 7.9.1 Rotorcraft(Sik0rsky)）.… 122 7.9.1.1 Damage .. 122 7.9.1.2 Environment. .122 7.9.1.3 Test loading conditions related to critical failure modes..............................122 7.9.1.4 Test loads-load enhancement factor (LEF)................................122 7.9.1.5 Spectrum - 7.9.1.6 Residual strength test.......... 124 7.9.2 Commercial aircraft (Boeing 777 empennage torque boxes)......................................1.24 7.9.2.1 Durability-environmental..124 7.9.2.2 Durability -mechanical loads..........125 7.9.2.3 7.9.2.4 Damage tolerance-"no growth"tests... 125 7.9.2.5 Damage tolerance-residual strength 127 7.9.2.6 Inspection plan....... ..127 7.9.3 General aviation (Raytheon Starship).............. 127 7.9.3.1 Introduction..127 7.9.3.2 Damage tolerance evaluation..... 128 7.9.3.2.1 Regulatory basis........... .128 7.9.3.2.2 Typical damage scenarios and related requirements..........................128 7.9.3.2.3 Damage source and modes..... 128 7.9.3.2.4 Element testing ...129 7.9.3.2.5 Test results..... .130 7.9.3.2.6 Full scale tests.… 134 7.9.3.2.7 Continued airworthiness inspections................... 135 7.9.3.3 Service experience 135 7.9.3.4 Conclusions.............. 136 7.9.4 Military aircraft...… .136 CHAPTER 8 SUPPORTABILITY 8.1 INTRODUCTION... 1 8.2 DESIGN FOR SUPPORTABILITY................... 8.2.1 In-service experience...................... 2 8.2.2 Inspectability... 8.2.2.1 General design guidelines................. 5 8.2.2.2 Accessibility for inspection..... 1 8.2.3 Material selection............. 8.2.3.1 Introduction.… > 8.2.3.2 Resins and fibers................... .7 8.2.3.3 8.2.3.4 Adhesives... 9 8.2.3.5 Supportability issues.. 9 8.2.3.6 Environmental concerns ............... i.9 8.2.4 Damage resistance,damage tolerance,and durability.......................................11 8.2.4.1 Damage resistance. 11 8.2.4.2 Damage tolerance.… 12 xiiMIL-HDBK-17-3F Volume 3, Foreword / Table of Contents xii 7.8.4.1.3 LEFM - based methods....................................................................... 109 7.8.4.1.4 R-curves...............................................................................................110 7.8.4.2 Single delaminations and disbonds................................................................113 7.8.4.2.1 Fracture mechanics approaches..........................................................114 7.8.4.2.2 Sublaminate buckling methods............................................................114 7.8.4.3 Impact damages .............................................................................................115 7.8.4.3.1 Sublaminate buckling methods............................................................115 7.8.4.3.2 Strain softening methods .....................................................................119 7.8.4.4 Cuts and gouges............................................................................................ 121 7.9 APPLICATIONS/EXAMPLES................................................................................................. 121 7.9.1 Rotorcraft (Sikorsky) .................................................................................................... 122 7.9.1.1 Damage ......................................................................................................... 122 7.9.1.2 Environment................................................................................................... 122 7.9.1.3 Test loading conditions related to critical failure modes ................................ 122 7.9.1.4 Test loads - load enhancement factor (LEF) ................................................. 122 7.9.1.5 Spectrum - truncation .................................................................................... 123 7.9.1.6 Residual strength test.................................................................................... 124 7.9.2 Commercial aircraft (Boeing 777 empennage torque boxes)...................................... 124 7.9.2.1 Durability - environmental.............................................................................. 124 7.9.2.2 Durability - mechanical loads......................................................................... 125 7.9.2.3 Damage ......................................................................................................... 125 7.9.2.4 Damage tolerance - "no growth" tests ........................................................... 125 7.9.2.5 Damage tolerance - residual strength ........................................................... 127 7.9.2.6 Inspection plan............................................................................................... 127 7.9.3 General aviation (Raytheon Starship).......................................................................... 127 7.9.3.1 Introduction .................................................................................................... 127 7.9.3.2 Damage tolerance evaluation........................................................................ 128 7.9.3.2.1 Regulatory basis ................................................................................. 128 7.9.3.2.2 Typical damage scenarios and related requirements ......................... 128 7.9.3.2.3 Damage source and modes................................................................ 128 7.9.3.2.4 Element testing ................................................................................... 129 7.9.3.2.5 Test results.......................................................................................... 130 7.9.3.2.6 Full scale tests .................................................................................... 134 7.9.3.2.7 Continued airworthiness inspections .................................................. 135 7.9.3.3 Service experience ........................................................................................ 135 7.9.3.4 Conclusions ................................................................................................... 136 7.9.4 Military aircraft.............................................................................................................. 136 CHAPTER 8 SUPPORTABILITY.......................................................................................................... 1 8.1 INTRODUCTION........................................................................................................................ 1 8.2 DESIGN FOR SUPPORTABILITY ............................................................................................. 2 8.2.1 In-service experience....................................................................................................... 2 8.2.2 Inspectability .................................................................................................................... 5 8.2.2.1 General design guidelines ................................................................................. 5 8.2.2.2 Accessibility for inspection................................................................................. 7 8.2.3 Material selection............................................................................................................. 7 8.2.3.1 Introduction ........................................................................................................ 7 8.2.3.2 Resins and fibers............................................................................................... 7 8.2.3.3 Product forms .................................................................................................... 9 8.2.3.4 Adhesives .......................................................................................................... 9 8.2.3.5 Supportability issues.......................................................................................... 9 8.2.3.6 Environmental concerns .................................................................................... 9 8.2.4 Damage resistance, damage tolerance, and durability ..................................................11 8.2.4.1 Damage resistance...........................................................................................11 8.2.4.2 Damage tolerance ........................................................................................... 12