CHAPTER 7 SURFACE FAILURE ______________________________________ 419

7.0

Introduction ................................................................................................. 419

7.1

Surface Geometry ........................................................................................ 421

7.2

Mating Surfaces ........................................................................................... 423

7.3

Friction ......................................................................................................... 424

Effect of Roughness on Friction

425

Effect of Velocity on Friction

425

Rolling Friction

425

Effect of Lubricant on Friction

426

7.4

Adhesive Wear ............................................................................................. 426

The Adhesive-Wear Coefficient

429

7.5

Abrasive Wear ............................................................................................. 430

Abrasive Materials

433

Abrasion-Resistant Materials

433

7.6

Corrosion Wear ............................................................................................ 434

Corrosion Fatigue

435

Fretting Corrosion

435

7.7

Surface Fatigue.............................................................................................. 436

7.8

Spherical Contact ......................................................................................... 438

Contact Pressure and Contact Patch in Spherical Contact

438

Static Stress Distributions in Spherical Contact

440

 

xiii

7.9

Cylindrical Contact ...................................................................................... 444

Contact Pressure and Contact Patch in Parallel Cylindrical Contact 444

Static Stress Distributions in Parallel Cylindrical Contact

445

7.10 General Contact ........................................................................................... 448

Contact Pressure and Contact Patch in General Contact

448

Stress Distributions in General Contact

450

7.11 Dynamic Contact Stresses ............................................................................ 453

Effect of a Sliding Component on Contact Stresses

453

7.12 Surface Fatigue Failure Models—Dynamic Contact .................................... 461

7.13 Surface Fatigue Strength............................................................................... 464

7.14 Summary ..................................................................................................... 470

Designing to Avoid Surface Failure

471

7.15 References ................................................................................................... 474

7.16 Problems ...................................................................................................... 476