1 / 15

Fatigue Failure Through Bending David Burnette ME 498

Fatigue Failure Through Bending David Burnette ME 498. Overview. Objectives of experiment Importance and theory Experimental details Result Conclusions and recommendations. Objectives. To become familiar with fatigue testing procedures

spike
Download Presentation

Fatigue Failure Through Bending David Burnette ME 498

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Fatigue Failure Through Bending David Burnette ME 498

  2. Overview • Objectives of experiment • Importance and theory • Experimental details • Result • Conclusions and recommendations

  3. Objectives • To become familiar with fatigue testing procedures • Develop fatigue data for AA 6061-T6 specimens • Extrapolate the endurance limit from the S-N curve (at 5x10^8 cycles) • Compare estimated endurance limit and cycles to failure to known • Evaluate the surface characteristics of fatigue failure

  4. What is Fatigue? Crack Propagation • Examples of Fatigue Factors • Size, loading types • Stress concentration factors • temperature, corrosion

  5. Testing Procedures - Application of Stresses

  6. Test Specimens – Cycles to Failure Comparison Aluminum Alloys: Nearly pure (>95%), precipitation hardening, tempering, lack of carbon

  7. 3 1 D C B A 4 2 Experimental Setup Bending Stress LOAD Cantilever Arm Motor 6061-T6 specimen

  8. Results • Endurance limit for 6061-T6 alloy at 5x108 • Predicted Cycles to Failure v. Observed • Fracture Surface

  9. Results - Chauvenet N d/σ 5 1.65 6 1.73 7 1.81 8 1.86 9 1.91 10 1.96 12 2.04 14 2.10 16 2.15 18 2.20 20 2.24 1 data point removed with Chauvenet’s: D=σ *(d/σ)

  10. Results - Predicted Cycles Causes of Error eccentricity (set screw), yield strength, diameter, number of points (12)

  11. σe = 85 MPa

  12. Results - Diameter Uncertainty I =

  13. Results - Surface conditions • Fatigue failure versus dynamic failure • Crack Propagation

  14. Conclusions • Fatigue failure is very different than static or dynamic failures • A small change in diameter can significantly increase the stress • Wide range of deviations (Factor of Safety) • Difference of only 10.5% with eccentricity (human error), diameter uncertainty, alloy uncertainty, etc

  15. Recommendations • Replace set screws with chuck or threaded specimens • Increase size of aluminum specimens (fewer points)

More Related