As an individual, develop a spreadsheet based design tool which assists in bolted joint design. The bolted joints to be analysed will take the general form of the example shown in Figure 1 below. However, the number of bolts in the bolt pattern, the magnitude and direction of the applied load and the arrangement of the bolts will vary from design-to-design. Consequently your analysis tool should be flexible enough to accommodate such variations The bolted joint design tool must determine the shear stresses induced in each of the bolts for a given fastener pattern of a bolted joint. Furthermore, the facility must identify the minimum bolt factor of safety in the joint. To achieve this it is anticipated that the design tool should (at least) accept and process the following input from the user: Bolt grade Suggested bolt diameter Number of bolts in pattern Bolt locations (x, y) Load magnitude and direction
Great walk-through. A question regarding the bolt. If we pretension the bolt to X Newtons the bolt will experience (X/ area) of tensile stress. The clamp force will be sufficient to carry a shear force of (X*µ) newtons. But when we add the maximum shear force (x*µ) this should also add a shear force to the bolt itself. The total stress of the bolt should then become a combination of the tensile stress and the shear stress, e.g. vonMises of the two. So in theory, lets say we pretension the screw close to its' yield force/ stress. We determine the max shear load it can withstand (N*µ) and apply the max shear. Shouldn't this lead to a higher vonMises stress in the bolt that might exceed the yield stress? Have I missed something or is the shear stress in the bolt negligible?
The shear stress is carried by friction between the two clamped plates and not by the bolt at all. Your concern would be valid if the bolted joint had slipped and the shear stress was carried over the bolt. The bolt will be carrying some torsional shear stress if it is torque tightened of course and we should not forget about this.
As an individual, develop a spreadsheet based design tool which assists in bolted joint design.
The bolted joints to be analysed will take the general form of the example shown in Figure 1
below. However, the number of bolts in the bolt pattern, the magnitude and direction of the
applied load and the arrangement of the bolts will vary from design-to-design. Consequently
your analysis tool should be flexible enough to accommodate such variations
The bolted joint design tool must determine the shear stresses induced in each of the bolts
for a given fastener pattern of a bolted joint. Furthermore, the facility must identify the
minimum bolt factor of safety in the joint. To achieve this it is anticipated that the design tool
should (at least) accept and process the following input from the user:
Bolt grade
Suggested bolt diameter
Number of bolts in pattern
Bolt locations (x, y)
Load magnitude and direction
Great walk-through.
A question regarding the bolt.
If we pretension the bolt to X Newtons the bolt will experience (X/ area) of tensile stress.
The clamp force will be sufficient to carry a shear force of (X*µ) newtons.
But when we add the maximum shear force (x*µ) this should also add a shear force to the bolt itself.
The total stress of the bolt should then become a combination of the tensile stress and the shear stress, e.g. vonMises of the two.
So in theory, lets say we pretension the screw close to its' yield force/ stress.
We determine the max shear load it can withstand (N*µ) and apply the max shear.
Shouldn't this lead to a higher vonMises stress in the bolt that might exceed the yield stress?
Have I missed something or is the shear stress in the bolt negligible?
The shear stress is carried by friction between the two clamped plates and not by the bolt at all. Your concern would be valid if the bolted joint had slipped and the shear stress was carried over the bolt. The bolt will be carrying some torsional shear stress if it is torque tightened of course and we should not forget about this.