1 / 20

ENGI 1313 Mechanics I

ENGI 1313 Mechanics I . Lecture 38: Examples of Friction Analysis. Lecture 38 Objective. to illustrate the equilibrium analysis of rigid bodies subjected to dry friction force by example. Miscellaneous Notes. Lecture 37 Notes Have Been Reposted Minor corrections

pooky
Download Presentation

ENGI 1313 Mechanics I

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. ENGI 1313 Mechanics I Lecture 38: Examples of Friction Analysis

  2. Lecture 38 Objective • to illustrate the equilibrium analysis of rigid bodies subjected to dry friction force by example

  3. Miscellaneous Notes • Lecture 37 Notes Have Been Reposted • Minor corrections • Quiz and Mid-Term Marks Posted

  4. Example 38-01 • The 800-lb concrete pipe is being lowered from the truck bed when it is in the position shown. If the coefficient of static friction at the points of support A and B is μs = 0.4, determine where it begins to slip first: at A or B, or both at A and B.

  5. Example 38-01 (cont.) • Three Analysis Cases • Impending motion at A • Impending motion at B • Impending motion at A & B

  6. Example 38-01 (cont.) • Draw FBD y x FA FB NA W = 800lb NB

  7. Example 38-01 (cont.) • Assume Impending Motion at A & B • Analysis y x FA FB NA W = 800lb NB

  8. Example 38-01 (cont.) • Analysis y x FA FB NA W = 800lb NB

  9. Example 38-01 (cont.) • Assumption • What is Calculated • Check Assumption •  not correct y x FA FB NA W = 800lb NB

  10. Example 38-01 (cont.) • Assume Impending Motion at A y x FA FB NA W = 800lb NB

  11. Example 38-01 (cont.) • Analysis y x FA FB NA W = 800lb NB

  12. Example 38-01 (cont.) • Analysis y x FA FB NA W = 800lb NB

  13. Example 38-01 (cont.) • Assumption • What is Calculated • Check Assumption •  Slip impending at A y x FA FB NA W = 800lb NB

  14. Example 38-02 • The man having a weight of 150 lb pushes horizontally on the bottom of crate A, which is stacked on top of crate B. Each crate has a weight of 100 lb. If the coefficient of static friction between each crate is μs1 = 0.8 and between the bottom crate, his shoes, and the floor is μs2 = 0.3, determine if he can cause impending motion.

  15. Example 38-02 • Impending Motion? • A/B Interface • B/Floor Interface • Man/Floor Interface • Potential impending motion at all three interfaces (rare) • Crates tip

  16. Example 38-02 (cont.) • Assume Impending Motion for Crate A • FBD Crate A • Analysis FA W = 100lb NA

  17. Example 38-02 (cont.) • Assume Impending Motion for Crate B • FBD Crate B • Analysis FB W = 200lb NB

  18. Example 38-02 (cont.) • Assume Tipping • FBD Crate A & B • Analysis • Minimum P FB W = 200lb NB

  19. Example 38-02 (cont.) • Force Exerted by Man? • FBD • Analysis W Pmin FM NM  Impending motion

  20. References • Hibbeler (2007) • http://wps.prenhall.com/esm_hibbeler_engmech_1

More Related