- #1

davidwinth

- 101

- 8

- TL;DR Summary
- A bolt holds two members in compression, and is said to take less of the external load even when the numbers say different.

Hello,

I am studying through a machine design book and ran across this confusing statement which summarizes the results of an example problem. The problem has a bolt and nut that together hold two members in compression. The stiffness ratio is given as $$K_m = 6K_b$$. The bolt is preloaded with $$P_i = 1100 lbs$$ and the members have an external load (that tries to pull them apart) of $$F_e = 1200 lbs$$. The example then finds the resultant compression in the members and the tension in the bolts. The tension in the bolt is 1271.42 lbs and the compression in the members is 71.42 lbs. Then the book gives this statement: "In this problem, it can be seen that the proportion of the load shared by the bolt is very small because the stiffness of the bolt is low when compared to the members."

I am studying through a machine design book and ran across this confusing statement which summarizes the results of an example problem. The problem has a bolt and nut that together hold two members in compression. The stiffness ratio is given as $$K_m = 6K_b$$. The bolt is preloaded with $$P_i = 1100 lbs$$ and the members have an external load (that tries to pull them apart) of $$F_e = 1200 lbs$$. The example then finds the resultant compression in the members and the tension in the bolts. The tension in the bolt is 1271.42 lbs and the compression in the members is 71.42 lbs. Then the book gives this statement: "In this problem, it can be seen that the proportion of the load shared by the bolt is very small because the stiffness of the bolt is low when compared to the members."

**How is 1271.42 less than 71.42?**Thanks.
Last edited: