Answer to Question #98652 in Mechanical Engineering for Noah

Question

Problem 3 You are building a replica of Stonehenge and need to move the Sarsen stones. The stones each weigh 350 kN. There are always at least 4 logs under the stone. The total width of the sleds supported on each stone is 750mm. The modulus of elasticity for the logs is 14.9 GPa and Poisson's ratio 0.033

If the maximum contact stress allowed on a log is 70 MPa, what is the minimum diameter for the logs?

Answer 1

From Herz formula
Rmin=sqrt(350000N*14,9*10^3MPa/(4*750mm*2*3,1415*(1-0,033^2)*(70MPa)^2))=57mm
Where 350000/(4*750) - distributed load for one lug
For more conservative calculation can be assumed that force for one lug is equal 350kN and Rmin=226mm