Stresses in Circular Bolt Patterns

In summary, the threaded fasteners in a circular bolt pattern, such as those used in a flanged joint, collectively "share the load" by creating a frictional force that supports external loads. In a proper joint, the fasteners should only experience loads due to pretension. A google search for joint diagrams can provide further information on this topic. According to John Bickford, a renowned author on fasteners, it is common practice to assume that all bolts equally share the shear load and any tensile loads from axial forces in a flange bolt connection. The greatest tensile load in the bolts is typically caused by bending moments at the connection, with the outer bolt bearing the greatest load and the center bolts bearing none. The thickness
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Hello, all. Can someone please direct me to a good source of information which explains how the threaded fasteners in a circular bolt pattern - such as used in a flanged joint - collectively "share the load", and how the stresses which arise due to tension, bending, and shear forces acting upon that circular bolt pattern are distributed? The particular example that I have in mind is one which is comprised of a pair of carbon steel flanges connected by eight(8) @ 5/8"-18NC Socket Head Cap Screws and hexnuts arranged on a 6"-dia. bolt circle. If an ultimate material tensile strength of 170,000psi is used, what would be the maximum tensile and shear loads which could be supported by such an arrangement? Thanx!
 
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  • #3
The above not withstanding, I've always designed flange bolt connections assuming that all bolts equally share the shear load, and equally share any tensile loads from axial forces; then the greatest tensile load in the bolts comes from the bending moments at the connection, in which case the outer bolt sees the greatest load, the center bolts see none, etc., as determined from M/S calculations. It is then common practice to use equally sized bolts in the connection, to accommodate bending moments in any direction. The thickness of the flange plate is also calculated primarily from the bending moments.
 

FAQ: Stresses in Circular Bolt Patterns

1. What is a circular bolt pattern?

A circular bolt pattern is a geometric arrangement of bolts or fasteners in a circular shape. It is commonly used in engineering and construction to secure circular objects, such as pipes, wheels, or plates, to a supporting structure.

2. How do you calculate the stresses in a circular bolt pattern?

The stresses in a circular bolt pattern can be calculated using the formula: S = (F x L) / (A x n), where S is the stress, F is the force applied, L is the lever arm, A is the cross-sectional area of the bolt, and n is the number of bolts in the pattern. Additionally, factors such as bolt material, thread type, and tightening torque should also be considered in the calculation.

3. What are the common causes of failure in a circular bolt pattern?

The common causes of failure in a circular bolt pattern include overloading, incorrect bolt material or size, incorrect torque or tightening method, and fatigue due to repetitive loading. It is important to properly calculate and select bolts for a circular bolt pattern to avoid failure.

4. How can you prevent bolt loosening in a circular bolt pattern?

Bolt loosening in a circular bolt pattern can be prevented by using locking mechanisms such as lock washers or thread-locking adhesive, ensuring proper bolt tension, and using high-quality and properly sized bolts. Regular maintenance and inspections can also help identify and prevent potential loosening issues.

5. What are the advantages of using a circular bolt pattern?

Using a circular bolt pattern allows for even distribution of load and stress, making it a strong and stable choice for securing circular objects. It also allows for easier assembly and disassembly of the object, as bolts can be accessed from any angle. Additionally, the circular pattern can provide a more aesthetic appearance compared to a square or rectangular bolt pattern.

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