Contents xiii 6.12 Nonlinear stress-strain behavior 366 6.13 Mechanical properties 368 6.13.1 Friction and wear behavior 368 6.13.2 Notched strength 371 7 Three-dimensional textile structural composites 374 7.1 Introduction 374 7.2 Processing of textile preforms 376 7.2.1 Braiding 377 7.2.1.1 2-step braiding 377 7.2.1.2 4-step braiding 379 7.2.1.3 Solid braiding 382 7.2.2 Weaving 382 7.2.2.1 Angle-interlock multi-layer weaving 383 7.2.2.2 Orthogonal weaving 387 7.2.3 Stitching 387 7.2.4 Knitting 389 7.3 Processing windows for 2-step braids 389 7.3.1 Packing of fibers and yarn cross-sections 390 7.3.2 Unit cell of the preform 395 7.3.3 Criterion for yarn jamming 398 7.4 Yarn packing in 4-step braids 402 7.4.1 Unit cell of the preform 402 7.4.2 Criterion for yarn jamming 403 7.5 Analysis of thermoelastic behavior of composites 405 7.5.1 Elastic strain-energy approach 406 7.5.2 Fiber inclination model 407 7.5.3 Macro-cell approach 414 7.5.3.1 Geometric relations 414 7.5.3.2 Elastic constants 416 7.6 Structure-performance maps of composites 419 7.7 Mechanical properties of composites 428 7.7.1 Tensile and compressive behavior 428 7.7.2 Shear behavior 431 7.7.3 Fracture behavior 432 7.7.3.1 In-plane fracture 432 7.7.3.2 Interlaminar fracture 435 7.7.4 Impact 440 8 Flexible composites 443 8.1 Introduction 443 8.2 Cord/rubber composites 445Contents xiii 6.12 Nonlinear stress-strain behavior 366 6.13 Mechanical properties 368 6.13.1 Friction and wear behavior 368 6.13.2 Notched strength 371 7 Three-dimensional textile structural composites 374 7.1 Introduction 374 7.2 Processing of textile preforms 376 7.2.1 Braiding 377 7.2.1.1 2-step braiding 377 7.2.1.2 4-step braiding 379 7.2.1.3 Solid braiding 382 7.2.2 Weaving 382 7.2.2.1 Angle-interlock multi-layer weaving 383 7.2.2.2 Orthogonal weaving 387 7.2.3 Stitching 387 7.2.4 Knitting 389 7.3 Processing windows for 2-step braids 389 7.3.1 Packing of fibers and yarn cross-sections 390 7.3.2 Unit cell of the preform 395 7.3.3 Criterion for yarn jamming 398 7.4 Yarn packing in 4-step braids 402 7.4.1 Unit cell of the preform 402 7.4.2 Criterion for yarn jamming 403 7.5 Analysis of thermoelastic behavior of composites 405 7.5.1 Elastic strain-energy approach 406 7.5.2 Fiber inclination model 407 7.5.3 Macro-cell approach 414 7.5.3.1 Geometric relations 414 7.5.3.2 Elastic constants 416 7.6 Structure-performance maps of composites 419 7.7 Mechanical properties of composites 428 7.7.1 Tensile and compressive behavior 428 7.7.2 Shear behavior 431 7.7.3 Fracture behavior 432 7.7.3.1 In-plane fracture 432 7.7.3.2 Interlaminar fracture 435 7.7.4 Impact 440 8 Flexible composites 443 8.1 Introduction 443 8.2 Cord/rubber composites 445