xvi CONTENTS 12.7 A Value Engineering Approach to the Use of Composite Materials 466 12.8 Conclusion 474 References 474 Chapter 13 Airworthiness Considerations For Airframe Structures 477 13.1 Overview 477 13.2 Certification of Airframe Structures 480 13.3 The Development of Design Allowables 482 13.4 Demonstration of Static Strength 484 13.5 Demonstration of Fatigue Strength 486 13.6 Demonstration of Damage Tolerance 487 13.7 Assessment of the Impact Damage Threat 487 References 488 Chapter 14 Three-Dimensionally Reinforced Preforms and Composites 491 14.1 Introduction 491 14.2 Stitching 492 14.3 Z-Pinning 498 14.4 Three-Dimensional Weaving 502 14.5 Braiding 507 14.6 Knitting 515 14.7 Non-crimp Fabrics 519 14.8 Conclusion 523 References 523 Chapter 15 Smart Structures 525 15.1 Introduction 525 15.2 Engineering Approaches 526 15.3 Selected Applications and Demonstrators 531 15.4 Key Technology Needs 544 References 545 Chapter 16 Knowledge-Based Engineering,Computer-Aided Design,and Finite Element Analysis 549 16.1 Knowledge-Based Design Systems 549 16.2 Finite Element Modelling of Composite Structures 552 16.3 Finite Element Solution Process 553 16.4 Element Types 562 16.5 Finite Element Modelling of Composite Structures 563 16.6 Implementation 566 16.7 Design Optimization 568 References 569xvi CONTENTS 12.7 A Value Engineering Approach to the Use of Composite Materials 12.8 Conclusion References Chapter 13 Airworthiness Considerations For Airframe Structures 13.1 Overview 13.2 Certification of Airframe Structures 13.3 The Development of Design Allowables 13.4 Demonstration of Static Strength 13.5 Demonstration of Fatigue Strength 13.6 Demonstration of Damage Tolerance 13.7 Assessment of the Impact Damage Threat References Chapter 14 Three-Dimensionally Reinforced Preforms and Composites 14.1 Introduction 14.2 Stitching 14.3 Z-Pinning 14.4 Three-Dimensional Weaving 14.5 Braiding 14.6 Knitting 14.7 Non-crimp Fabrics 14.8 Conclusion References Chapter 15 Smart Structures 15.1 15.2 15.3 15.4 Chapter 16 Introduction Engineering Approaches Selected Applications and Demonstrators Key Technology Needs References Knowledge-Based Engineering, Computer-Aided Design, and Finite Element Analysis 16.1 Knowledge-Based Design Systems 16.2 Finite Element Modelling of Composite Structures 16.3 Finite Element Solution Process 16.4 Element Types 16.5 Finite Element Modelling of Composite Structures 16.6 Implementation 16.7 Design Optimization References 466 474 474 477 477 480 482 484 486 487 487 488 491 491 492 498 502 507 515 519 523 523 525 525 526 531 544 545 549 549 552 553 562 563 566 568 569