1. Choose a key material from Table 02 above and document your choice of material and temper in your work.

I used Tin Brass (Sy= 55000posi, Su=6000 ksi, E=16000, elongation: 6%) Hardness 76)

 

 

2. Using your Part 1 torque values (problem 15) T_B and T_C determine force F that the shaft exerts on the keys.

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AB BC CD DS FC1 FC2 DPB pulley A B C D Po Bearing Thrust Bearing FB1 FB2 DPC pulley DRAWING
NOT TO SCALE Course Project - KEY Material Table CAL OF Part 1 Direct Compression stress and
deformation For step 13 make of choice for key material from this selection Material Elong... 

3. Based on the given shaft diameter, use Diagram 2 to find the b and h values for your key.  NOTE: t = h/2 or t =d/8 are only for really small shaft diameters.

4. Using the shear force F from #2 above and shear stresses ?_B and ?_C (from Part 1C #20) find area A_s required (see Diagram 1) to support the shear load. (Hint see EQN 1-5)

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Diagram 1 Hub Shear plane F2 T = Torque T = F(D/2) F1 = Force of shaft on key Fa = Force of hub on
key --D = Shaft diameter Side view End view Metric Standard Parallel Keyway and Key Sizes Shaft
Diameter Keyway Key Diagram 2 mm (mm) (mm)* From To Width Depth Width Depth (W) (... 

5. Determine your key length L, good design practice requires length L = 2b minimum. Determine both values and compare.

6. What is your chosen key materials Factor of Safety (FOS)?  (Key requirement, ?_d > ?)

7. Combine the stresses due to normal bending and column type compression using superposition. Refer to Diagram 3 (textbook Figure 10-21 modified) and textbook Figure 8-18 for visualizing the combination.

8. In #7 above you found the combined stresses for the shaft top and bottom. State which is maximum?

9. Calculate the maximum shear stress using the equation developed in our textbook page 571 (shown here).  

10. What is AISI 1018 carburized at 925C (1700F) (yielding Factor of Safety (FOS) relative to ?_max?

11. First determine the end fixity values for the two bearing types supporting the shaft.  From textbook Figure 11-3.

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Le = 0.5L Fixed-fixed K = 0.5 K = 0.65

12. Second find the radius of gyration, r, for our shaft using textbook Appendix A-1.

13. Compute the slenderness ratio SR of the shaft. (Hint see EQN 11-1)

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Slenderness Ratio KL SR Le (11-1) where L = actual length of the column between points of support or
lateral restraint K = end-fixity factor Le = effective length, taking into account the manner of attaching
the ends (note that Le = KI) r= smallest radius of gyration of the cross section of the column

14. Determine the transition slenderness ratio C_C of the shaft. (Hint see EQN 11-3)

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(11-3) Transition Slenderness Ratio Cc Sy

15. Would this shaft be considered a long or short column? Substantiate your reasons why.

16. Determine the critical load P_cr of the shaft using the appropriate formula.

17. According to the maximum shear stress theory of failure, will this shaft safely transmit the load?  Substantiate your reasons why. (compute the values requested before writing an answer)

18. Would this shaft safely resist the compressive buckling load?  Substantiate your reasons why. (compute the values requested before writing an answer)

19. Is it reasonable to consider buckling in the design of this shaft? Substantiate your reasons why. (compute the values requested before writing an answer)