Stub axle calculations help please

In summary, the shear force is the same at every point on the axle between the point of application of the load and the point of resistance to the load. The bending moment is determined by the distance from the load to the reaction to the load, and varies linearly with the distance from the load to the reaction.
  • #1
jonny2k
3
0
i have been set a question to draw the shear force and bending moment diagrams for the loading condition shown on the diagram, and am not quite sure how to do this...

do i need to work out other forces along the diagram?

and help...much appriciated thanks!
 

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  • #2
This is a basic cantilever beam with a point load.
The shear force will be the same between the point of application of the load and the reaction to the load. The bending moment (force x length) will vary linearly with the distance from the load to the reaction to the load. The axle's variable geometry (indicating a non-prismatic beam) effects the distribution of internal stresses. The load diagrams are determined only by the nature of the loads (point, distributed, etc.) and the position and nature of the supports (free, pinned, fixed).

Chris

jonny2k said:
i have been set a question to draw the shear force and bending moment diagrams for the loading condition shown on the diagram, and am not quite sure how to do this...

do i need to work out other forces along the diagram?

and help...much appriciated thanks!
 
  • #3
with the axle fixed on the right hand side does this mean the only shear force is where the force is acting (in the centre of the 3rd block)?
 
  • #4
jonny2k said:
with the axle fixed on the right hand side does this mean the only shear force is where the force is acting (in the centre of the 3rd block)?

No. The shear force is acting on every arbitrary section between the point of application of the force and the reaction to the force at the right hand side. It's not just at the point of application of the load.

Chris
 
  • #5
so the force acting on each section is different? this is what's confusing me i think! how do i work out the different forces say at 6 points along the axle...
 
  • #6
jonny2k said:
so the force acting on each section is different? this is what's confusing me i think! how do i work out the different forces say at 6 points along the axle...

The shear force acting on each of the six points is the same. It is the same at any point on the axle between the point of application of the force and the point of resistance (reaction) to the force. You're imagining that the six points where the geometry changes have a special significance in regard to the shear force when they don't. The shear stress in the axle referenced along it's length does vary according to the cross sectional area at each point of interest. The geometry does come into play when looking at stress (force /area). If you had to draw the shear stress diagram then your concerns would have merit...but you're not being asked to draw the shear stress diagram. You're being asked to draw the shear force diagram. The shear force is constant and equal to the applied load at every possible vertical cut you might make in the axle between the point where the load is applied and the point where the load is resisted at the right hand end.

Chris
 

1. How do I calculate the load capacity of a stub axle?

The load capacity of a stub axle can be calculated by multiplying the maximum load per wheel by the number of wheels supported by the stub axle. This will give you the total load capacity for the stub axle.

2. What is the formula for determining the bending moment of a stub axle?

The bending moment of a stub axle can be calculated by multiplying the applied load by the distance from the center of the axle to the point of application.

3. How do I determine the minimum diameter for a stub axle?

The minimum diameter for a stub axle can be determined by considering the maximum load and the material properties of the axle. There are various formulas and charts available to help with this calculation.

4. What is the difference between static and dynamic loading in stub axle calculations?

Static loading refers to a constant load applied to the stub axle, while dynamic loading refers to a varying load that changes over time. Both types of loading must be considered in stub axle calculations to ensure the axle can handle the expected loads.

5. How do I account for shock loading in stub axle calculations?

Shock loading occurs when a sudden, high impact load is applied to the stub axle. To account for this, a safety factor is typically applied to the calculated load capacity of the axle. The safety factor will depend on the specific application and should be determined by a professional engineer.

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