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Causes of failure

ENMAT101A Engineering Materials and Processes Associate Degree of Applied Engineering (Renewable Energy Technologies) Lecture 26 – Causes of failure. Causes of failure. EMMAT101A Engineering Materials and Processes. 26.2 Causes of failure (Higgins 26.2). Overstressing (abuse)

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Causes of failure

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  1. ENMAT101A Engineering Materials and ProcessesAssociate Degree of Applied Engineering (Renewable Energy Technologies)Lecture 26 – Causes of failure

  2. Causes of failure EMMAT101A Engineering Materials and Processes

  3. 26.2 Causes of failure (Higgins26.2) Overstressing (abuse) Fatigue (Alternating loads) Creep (High temp) Sudden loads (earthquake, storm, accident) Expansion (or contraction) Thermal cycling (hot/cold stresses) Degradation (Environmental) EMMAT101A Engineering Materials and Processes

  4. 26.2 Causes of failure (Higgins26.2) 26.2.1 Types of fracture surfaces Ductile failure with metals Brittle failure with metals Fatigue failure with metals Failure with polymers Failure with ceramics Failure with composites EMMAT101A Engineering Materials and Processes

  5. 26.3 Non-destructive testing (Higgins26.3) 26.3.1 The detection of surface cracks and flaws Penetrant methods EMMAT101A Engineering Materials and Processes

  6. 26.3 Non-destructive testing (Higgins26.3) Magnetic particle methods EMMAT101A Engineering Materials and Processes

  7. 26.3 Non-destructive testing (Higgins26.3) Acid pickling methods EMMAT101A Engineering Materials and Processes

  8. 26.3 Non-destructive testing (Higgins26.3) 26.3.2 The detection of internal defects X-ray methods Gamma-ray methods EMMAT101A Engineering Materials and Processes

  9. 26.3 Non-destructive testing (Higgins26.3) Ultrasonic testing: Principle of ultrasonic testing. LEFT: A probe sends a sound wave into a test material. There are two indications, one from the initial pulse of the probe, and the second due to the back wall echo. RIGHT: A defect creates a third indication and simultaneously reduces the amplitude of the back wall indication. The depth of the defect is determined by the ratio D/Ep EMMAT101A Engineering Materials and Processes

  10. 26.4 Degradation of metals by oxidation (Higgins26.4) Oxidation 26.4.1 Attack by sulphur EMMAT101A Engineering Materials and Processes

  11. 26.4 Degradation of metals by electrolytic corrosion (Higgins26.4) Electrolytic corrosion is like a Battery. EMMAT101A Engineering Materials and Processes

  12. 26.4 Degradation of metals by electrolytic corrosion (Higgins26.4) 26.5.1 The Electrochemical (or Galvanic) Series EMMAT101A Engineering Materials and Processes

  13. 26.4 Degradation of metals by electrolytic corrosion (Higgins26.4) 26.5.2 Cladding of metal sheets EMMAT101A Engineering Materials and Processes

  14. 26.4 Degradation of metals by electrolytic corrosion (Higgins26.4) 26.5.2 Cladding of metal sheets EMMAT101A Engineering Materials and Processes

  15. 26.4 Degradation of metals by electrolytic corrosion (Higgins26.4) 26.5.3 Rusting of iron and steel EMMAT101A Engineering Materials and Processes

  16. 26.6 The protection of metal surfaces (Higgins26.6) 26.6.1 Painting 26.6.2 Stove-enamelling 26.6.3 Coating the surface with another metal Hot dipping Spraying Sherardising Electroplating Cladding 26.6.4 Protection by oxide coatings EMMAT101A Engineering Materials and Processes

  17. 26.6 The protection of metal surfaces (Higgins26.6) 26.6.5 Metals and alloys which are inherently corrosion-resistant 26.6.6 Galvanic protection EMMAT101A Engineering Materials and Processes

  18. 26.4 Degradation of metals by electrolytic corrosion (Higgins26.4) 26.5.4 Stress corrosion EMMAT101A Engineering Materials and Processes

  19. 26.7 Stability of plastics (Higgins26.7) 26.7.1 Weathering of plastics materials 26.7.2 Perishing of rubbers 26.7.3 Stress cracking and crazing of polymers 26.7.4 Stability to solvents EMMAT101A Engineering Materials and Processes

  20. 26.8 Preservation of timber (Higgins26.8) 26.8.1 Insect pests 26.8.2 Fungus attack EMMAT101A Engineering Materials and Processes

  21. 26.9 Service life (Higgins 26.9) • External loading levels, rate of loading (impact loading), frequency of loading (fatigue), duration of loading (creep). • Material property degradation (corrosion). • Defects in the form of cracks, porosity (in castings), cavities (in welds) introduced during manufacturing. • Conditions under which used, e.g. temperature, temperature cycling, humidity, chemicals, contact with other materials. • Bad design features such as the presence of notches, sharp corners, small holes, surface roughness. • Lack of, or inappropriate, maintenance. EMMAT101A Engineering Materials and Processes

  22. Videos Joining Metals Sheppard, Phil. Bendigo, Vic. : Classroom Video, c2006. DVD (29 min.). An introduction to the methods of joining metals, including riveting and fusion and non-fusion methods of welding. Mt Druitt College Library: DVD 671.5/JOIN Joining Metals Notes (pdf) Recommended Viewing: All sections. EMMAT101A Engineering Materials and Processes

  23. Resources. Wikipedia: Welding Ashby diagrams EMMAT101A Engineering Materials and Processes

  24. Glossary Sacrificial anode Galvanising Electro-negativity Stress corrosion Electrolysis Oxidation Ductile/brittle failure Fatigue failure EMMAT101A Engineering Materials and Processes

  25. QUESTIONS: Joining of Materials Higgins Ch26, Newell, Timmings, Sheedy, Callister, Ashby • Define all glossary terms • (a) Explain what is meant by the term corrosion. (b) List three essential conditions for corrosion to occur. (c) Describe how an anode and cathode can be formed. (d) Describe how corrosion can be controlled or prevented. • Briefly describe the different types of corrosion listed below: • (a) uniform (general) corrosion • (b) galvanic corrosion • (c) crevice corrosion • (d) stress corrosion • (e) corrosion fatigue • (f) de-alloying (selective leaching), for example de-zincification • (g) high temperature (dry) oxidation corrosion • Briefly outline the processes by which plastics suffer degradation • Explain the differences between corrosion resistance of platinium and titanium. What other metals would fall into each of these two groups? • Describe ways to counter galvanic corrosion in PhotoVoltaic systems. http://www.civicsolar.com/node/10621 EMMAT101A Engineering Materials and Processes

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