Bolted Joint Analysis using BOLTCALC

This presentation presents an example of a basic bolted joint analysis using the BOLTCALC program. Metric units and thread sizes are used in this presentation, and shows how the BOLTCALC program can be used to check whether a bolted joint will be capable of sustaining the applied forces. It shows a basic joint analysis of a simple joint, more complex joints can be modelled using BOLTCALC.

What is a Joint Analysis?

A joint analysis is used to establish whether a bolted joint is structurally sound, that is, whether a failure can be anticipated. The BOLTCALC program can complete such an analysis. It will check whether the joint is adequate considering the following five possible failure modes:

That there is sufficient bolt preload to resist the forces acting on the joint. That is, the joint plates will not slip nor separate.

That the bolt will not sustain yielding as a result of the forces applied to the joint.

That the bolt will not sustain fatigue failure.

That thread stripping will not occur.

That the bearing pressure on each joint interface is within acceptable limits.

Example Joint Problem - M10 Bolts

A seat bolted on a rollercoaster must sustain dynamic forces. To prevent self-loosening, wear and fatigue, the joint must not slip, nor the plates separate. The joint shown consists of a number of M10 bolts, the highest loaded is shown below. The specific details are as follows:

Thread size: M10 (coarse thread)

Outer bearing dia. of the bolt: 14.6 mm

Clearance hole dia. 10.5 mm

Property class of the bolt: 8.8

Coefficient of friction 0.12 to 0.18

Axial force applied to the joint: 4500 N

Shear force applied to the joint: 1500 N

Coefficient of friction between the joint plates: 0.2
In order to ensure that the bolt is not overtightened, the lowest value of friction should be used in the calculations. In this case, since the coefficient of friction can vary between 0.12 and 0.18, 0.12 will be used in these calculations.

The screen capture video below shows the program being used to investigate whether the design of the joint is fit for purpose.