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R F9 Physics of Failure

R F9 Physics of Failure. Sliding contact phenomena Material related failure. RF9 Program Day 2. 9:00-9:15 Introduction 9:15-9:30 Friction related failures 9:30-10:00 Demo load capacity of sliding contacts 10:00-10:15 Break

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R F9 Physics of Failure

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  1. RF9 Physics of Failure Sliding contact phenomena Material related failure

  2. RF9 Program Day 2 RF9 - Physics of Failure 9:00-9:15 Introduction 9:15-9:30 Friction related failures 9:30-10:00 Demo load capacity of sliding contacts 10:00-10:15 Break 10:30-11:30 PoF Friction11:30-11:45 Application of gained results 11:45-12:30 PoF Wear 12:30-13:30 Lunch 13:30-14:00 Demo Dry Sliding and EP additives 14:00-15:00 PoF Material selection  15:00-15:15 Break 15:15-16:15 PoF Lubrication 16:15-16:45 Application of gained results 16:45-17:00 Summary of the day

  3. Material & Coating Selection RF9 - Physics of Failure – Material Selection • Adv Eng Design Page 222

  4. Case study Storm surge Barrier A movable storm surge barrier is constructed making dikes along the river unnecessary. RF9 - Physics of Failure – Material Selection • Adv Eng Design Page 222

  5. Case study Storm surge Barrier F=35.000 Metric Tonnes Load m=15.000 Metric Tonnes Load p<150 MPa µ<0.1 Material selection ? RF9 - Physics of Failure – Material Selection • Adv Eng Design Page 222

  6. Material & Coating Selection 7.1 Materials in relative sliding Metals, polymers, technical ceramics 7.2 Coatings and surface treatments Surface treatments and classification 7.3 Material selection Case study: storm surge barrier RF9 - Physics of Failure – Material Selection • Adv Eng Design Page 222

  7. Material Selection: Metals steel, bronze, cast iron… PF9 - Physics of Failure – Material Selection • Adv Eng Design Page 249

  8. Material Selection: Metals Why metal-metal combinations are always lubricated. Without lubrication: Without lubrication Severe adhesive friction / adhesive wear Metals of relativehigh hardness: Metals of relativelow hardness: + Relative good wear resistance (class 4) • High friction, scatter (µ=0.3...0.6) + Relative low friction (µ=0.08...0.14) - High wear rate (class 6) RF9 - Physics of Failure – Material Selection • Adv Eng Design Page 249

  9. Case 1 Seminar - Physics of Failure

  10. Material Selection: Metals How to reduce friction and wear due to adhesion • Combinations of a non-metal against a metal • Carburizing or nitriding • High hardness of both surfaces • Difference in hardness of a factor between 3 to 5 • High roughness • Strong oxide film • Lubricant, liquid or solid • Thin layer with low shear strength. RF9 - Physics of Failure – Material Selection • Adv Eng Design Page 169

  11. Material Selection: Metals How to reduce friction and wear due to adhesion • Combinations of a non-metal against a metal • Carburizing or nitriding • High hardness of both surfaces • Difference in hardness of a factor between 3 to 5 • High roughness • Strong oxide film • Lubricant, liquid or solid • Thin layer with low shear strength. RF9 - Physics of Failure – Material Selection • Adv Eng Design Page 169

  12. Material Selection: Polymers µ(p,v) Dependent on heat conduction RF9 - Physics of Failure – Material Selection • Adv Eng Design Page 209

  13. Material Selection: Polymers Polymers • Thermoplastics two types of thermoplastics - crystalline - amorphous • Thermosets cannot be reshaped by heating are stiff and strong in relation to thermoplastics are often reinforced with glass or carbon fibers • Elastomers rubbery polymers, can stretch easily and instantly return to its original shape when released. RF9 - Physics of Failure – Material Selection • Adv Eng Design Page 309

  14. Material Selection: Polymers Thermoplastics + Do not need to be lubricated + Low weight + Injection molding - Low stiffness and strength - Mechanical properties strongly depend on temp - Poor heat conduction, large thermal expansion - Large machining tolerances RF9 - Physics of Failure – Material Selection • Adv Eng Design Page 309

  15. Material Selection: Polymers RF9 - Physics of Failure – Material Selection • Adv Eng Design Page 253

  16. Material Selection: Polymers Amorphous plastics + Less mold shrinkage - Susceptible to chemical attack - Lower wear resistance Crystalline plastics + Higher strength and rigidity + Higher wear resistance + Good chemical resistance to oils and grease (silicone based oils, water, soap…) RF9 - Physics of Failure – Material Selection • Adv Eng Design Page 253

  17. Material Selection: Polymers price RF9 - Physics of Failure – Material Selection • Adv Eng Design Page 257

  18. Material Selection: Polymers RF9 - Physics of Failure – Material Selection • Adv Eng Design Page 261

  19. Material Selection: Polymers Self lubricating plastics are compounded with - PTFE, MoS2, Graphite, Silicone oil, Aramid fibres Fiber reinforced plastics are reinforced with - Glass fibers, Carbon fibers Steel counter surface - HRc>50, Ra=0.3-0.4 μm Aramid fibers - Improves resistance to abrasion especially against counter surfaces of lower hardness such as aluminum and plastics. The low friction is a result of a stronglyadhering transfer film on the counter surface Water lubrication precludes the formation of adry lubricant film, resulting in high wear rate RF9 - Physics of Failure – Material Selection • Adv Eng Design Page 260

  20. Material Selection: Polymers RF9 - Physics of Failure – Material Selection • Adv Eng Design Page 258, 261

  21. Case 2 Bronze St.50 (1.0050) Pmax=10…20 MPa Pmax=5…10 MPa Failure mode: RF9 - Physics of Failure – Material Selection • Adv Eng Design Page 222

  22. Material Selection: Metals How to reduce friction and wear due to adhesion • Combinations of non-metals or a non-metal against a metal • Carburizing or nitriding • High hardness of both surfaces • Difference in hardness of a factor between 3 to 5 • High roughness • Strong oxide film • Lubricant, liquid or solid • Thin layer with low shear strength. RF9 - Physics of Failure – Material Selection • Adv Eng Design Page 169

  23. Material Selection: Metals How to reduce friction and wear due to adhesion • Combinations of non-metals or a non-metal against a metal • Carburizing or nitriding • High hardness of both surfaces • Difference in hardness of a factor between 3 to 5 • High roughness • Strong oxide film • Lubricant, liquid or solid • Thin layer with low shear strength. RF9 - Physics of Failure – Material Selection • Adv Eng Design Page 169

  24. Material Selection: Metals Difference in hardness of a factor between 3 to 5 • Less tendency to adhesion (Pb, Sn) • Good embed ability for abrasive particles • Leveling out of stress concentrations RF9 - Physics of Failure – Material Selection • Adv Eng Design Page 250

  25. Material Selection: Metals Main bearing Marine bearing RF9 - Physics of Failure – Material Selection • Adv Eng Design Page 222

  26. Material Selection: Metals Elastic support Porous bearing Oil circulation within the pores RF9 - Physics of Failure – Material Selection • Adv Eng Design Page 210

  27. Material Selection: Metals Hardened shaft Porous iron RF9 - Physics of Failure – Material Selection • Adv Eng Design Page 222

  28. Material Selection: Metals Porous bronze (PbSn) bearings μ=0.06-0.10, k=0.3-0.9 10-15 m2/N, PV=1.75 106 Pa·m/s RF9 - Physics of Failure – Material Selection • Adv Eng Design Page 222

  29. Case 3 RF9 - Physics of Failure – Material Selection • Adv Eng Design Page 306, 35, 221

  30. Material Selection: Metals How to reduce friction and wear due to adhesion • Combinations of non-metals or a non-metal against a metal • Carburizing or nitriding • High hardness of both surfaces • Difference in hardness of a factor between 3 to 5 • High roughness • Strong oxide film • Lubricant, liquid or solid • Thin layer with low shear strength. RF9 - Physics of Failure – Material Selection • Adv Eng Design Page 169

  31. Material Selection: Metals How to reduce friction and wear due to adhesion1) : • Combinations of a non-metal against a metal • Carburizing or nitriding • High hardness of both surfaces • Difference in hardness of a factor between 3 to 5 • High roughness • Strong oxide film • Lubricant, liquid or solid  • Thin layer with low shear strength Layered molecular structure of graphite Stainless steel Thin oxide layer Stainless steel bolts require special purpose lubricants RF9 - Physics of Failure – Material Selection • Adv Eng Design Page 169

  32. AF-Coating (MoS2, graphite) Case 3 Layered molecular structure of graphite Successful application in clearance fits to prevent fretting corrosion (left) or galling (right) RF9 - Physics of Failure – Material Selection • Adv Eng Design Page 306, 35, 221

  33. Material Selection: Metals AF-Coating, P>100MPa, µ<0.1 Layered molecular structure of graphite Particle orientation after initial sliding AF-Coating (MoS2, graphite) Successful application in screw joints RF9 - Physics of Failure – Material Selection • Adv Eng Design Page 306

  34. Material Selection: Metals Layered molecular structure of graphite RF9 - Physics of Failure – Material Selection • Adv Eng Design Page 309

  35. Material Selection: Metals How to reduce friction and wear due to adhesion1) : • Combinations of non-metals or a non-metal against a metal • Carburizing or nitriding • High hardness of both surfaces • Difference in hardness of a factor between 3 to 5 • High roughness • Strong oxide film • Lubricant, liquid or solid • Thin layer with low shear strength  Galvanized High corrosion resistance RF9 - Physics of Failure – Material Selection • Adv Eng Design Page 169

  36. Material Selection: Metals How to reduce friction and wear due to adhesion • Combinations of a non-metal against a metal • Carburizing or nitriding • High hardness of both surfaces • Difference in hardness of a factor between 3 to 5 • High roughness • Strong oxide film • Lubricant, liquid or solid • Thin layer with low shear strength. Case 4 RF9 - Physics of Failure – Material Selection • Adv Eng Design Page 169

  37. Material Selection: Tech. Ceramics Al2O3 = Alumina SiC = Silicon Carbide Si3N4 = Silicon Nitride ZrO2 = Zirconia ZTA = Zirconia Toughened Alumina + High hardness and wear resistance + Low specific weight + Excellent high temperature properties + Resistance to corrosive environment - Low toughness (brittle) RF9 - Physics of Failure – Material Selection • Adv Eng Design Page 267

  38. Material Selection: Tech. Ceramics RF9 - Physics of Failure – Material Selection • Adv Eng Design Page 151

  39. Material Selection: Tech. Ceramics + High resistance to abrasive wear (elastic deformation) + High resistance to adhesive wear (small γ/H ratio) High surface energy but small ratio of surface energy and hardness RF9 - Physics of Failure – Material Selection • Adv Eng Design Page 151

  40. Material Selection: Tech. Ceramics Hydrodynamic bearing operating in abrasive environment (Pavg= 6 MPa) RF9 - Physics of Failure – Material Selection • Adv Eng Design Page 266

  41. Material Selection: Tech. Ceramics Jewel bearings Industrial jewels Diamond pivots RF9 - Physics of Failure – Material Selection • Adv Eng Design Page 504, 523

  42. Case 5 RF9 - Physics of Failure – Material Selection • Adv Eng Design Page 169

  43. Material Selection: Metals How to reduce friction and wear due to adhesion • Combinations of non-metals or a non-metal against a metal • Carburizing or nitriding • High hardness of both surfaces • Difference in hardness of a factor between 3 to 5 • High roughness • Strong oxide film • Lubricant, liquid or solid • Thin layer with low shear strength. Case 5 RF9 - Physics of Failure – Material Selection • Adv Eng Design Page 169

  44. Bonding strength Material Selection: Coatings & surface treatments RF9 - Physics of Failure – Material Selection • Adv Eng Design Page 269

  45. Material Selection: Coatings & surface treatments RF9 - Physics of Failure – Material Selection • Adv Eng Design Page 270

  46. Material Selection: Coatings & surface treatments Advantage of dissimilar materials(Metallurgical incompatible materials). RF9 - Physics of Failure – Material Selection • Adv Eng Design Page 268

  47. Material Selection Introducing residual compressive stressesup to half the yield strength in order to improve the fatigue strength. Laser peening imparts a layer of compressive stress that is four timesdeeper than that attainable from conventional shot peening RF9 - Physics of Failure – Material Selection • Adv Eng Design Page 273

  48. Material Selection: Coatings & surface treatments Nickel and chromium plating PF9 - Physics of Failure – Material Selection • Adv Eng Design Page 268

  49. Material Selection: Coatings & surface treatments Laser cladding Laser cladding is an effective way to refurbish and improve worn or damaged industrial components RF9 - Physics of Failure – Material Selection • Adv Eng Design Page 268

  50. Material Selection: Coatings & surface treatments Pre-machining: removal of worn and with lubricant diffused material Substrate low alloyedC-steel, Clad material Stellite 21 Post-machining to required dimensions RF9 - Physics of Failure – Material Selection • Adv Eng Design Page 273

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