Inertia Load Analysis on a Bolted Connection.

[Tom C]

{****not a homework question****}

This question has a slightly different theme than the typical torque and inertia problem - I have to determine stress on a bolt.

A steel block of mass M is bolted to the rim of a slowly rotating steel disc of radius R whose axis is horizontal; the rotating disc is subjected to starts and stops. The angular acceleration during each start and stop is known to be constant. It is required to find all the loads acting on the bolt so that a correct size and strength can be determined.

I think the worst case is when the block is positioned horizontally. When it is, I think that we have a static load due to its weight and this causes shear in the bolt; then also I think that it may have an inertia load due to acceleration during starts and stops that add to the static shear load in the bolt.

During rotation, I think that normal forces on the bolt cause a tensile load. Is this a correct assumption?

Are their any other loads on this bolt?

How to determine inertia load due acceleration during starts and stops?
How to determine the normal loads in the bolt during disc rotation?

Thanks for any tips.

 

[Achy47]

I would approach this problem by first understanding the physical principles involved. In this case, we are dealing with rotational motion and the forces acting on the bolt. The first step would be to draw a free body diagram of the system, including the block, the disc, and the bolt. This will help visualize all the forces acting on the bolt and their directions.

Next, I would use the equations of rotational motion to determine the inertia load on the bolt during the starts and stops. This can be calculated using the formula I = MR^2, where I is the moment of inertia, M is the mass of the block, and R is the radius of the disc.

To determine the normal loads on the bolt during disc rotation, we need to consider the centripetal force acting on the block. This force is given by Fc = Mv^2/R, where M is the mass of the block, v is the linear velocity of the block, and R is the radius of the disc. This force will act in the opposite direction of the normal force on the bolt, causing a tensile load.

In addition to these loads, we also need to consider the static load due to the weight of the block, which will cause a shear load on the bolt. This can be calculated using the formula F = mg, where m is the mass of the block and g is the acceleration due to gravity.

To determine the correct size and strength of the bolt, we would need to consider the maximum load that the bolt can withstand before failing. This can be determined using the yield strength of the bolt material and the safety factor required for the application.

Overall, the key to solving this problem is to carefully consider all the forces acting on the bolt and use the appropriate equations to calculate them. It may also be helpful to simulate the system using a computer program to verify the results. I hope these tips are helpful in solving this problem. Good luck!