# Calculate deflection of rod/axlepipe due to distributed load

• Krismein
In summary, the conversation discusses the process of manually calculating the deformation on a rod/axle/pipe due to a distributed load. The rod has specific dimensions and material properties, and the load is distributed along its entire length. The individual has calculated the second moment of inertia but is struggling to find a suitable formula for rod deformation. They mention using a formula from a Norwegian engineering book and clarify that this is for their bachelor thesis. The conversation also touches on the importance of considering the type of support for accurate calculations.
Krismein
Summary:: Calculate the deformation on a rod/axle/pipe due to a distributed load.

I’m manually trying to calculate the deformation on a rod/axle/pipe due to a distributed load. The rod has an outer diameter of 62mm and an inner diameter of 50, is 170mm long, made from a material with an E-module=200GPa and Poisson's ratio = 0,3. The load is distributed along the whole length of the rod and is 491 N/mm. I have calculated the second moment of inertia I to be 418536mm^4, and I’m having no luck finding a formula for rod deformation/bending.

I have tried using this formula:

But i don't think it applies for rods, as my answer is low.

Is this question for your work or is it a schoolwork question?

Where did you get that equation from?
The type of support is very important.

Lnewqban said:
Where did you get that equation from?
The type of support is very important.
From a Norwegian book for engineering. Posting a pic below.

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berkeman said:
Is this question for your work or is it a schoolwork question?
For my bachelor thesis

Nice. I'll move it to the schoolwork forums then.

## What is the formula for calculating deflection of a rod/axlepipe due to distributed load?

The formula for calculating deflection of a rod/axlepipe due to distributed load is: δ = (5wL^4)/(384EI), where δ is the deflection, w is the distributed load, L is the length of the rod/axlepipe, E is the modulus of elasticity, and I is the moment of inertia.

## What are the units for the variables in the deflection formula?

The units for the variables in the deflection formula are: δ - meters (m), w - newtons per meter (N/m), L - meters (m), E - pascals (Pa), and I - meters to the fourth power (m^4).

## Can the deflection formula be used for both rods and axlepipes?

Yes, the deflection formula can be used for both rods and axlepipes as long as the material properties (E and I) and the distributed load (w) are known. However, it is important to note that the formula assumes the rod/axlepipe is homogeneous and has a constant cross-sectional area.

Distributed load refers to a load that is spread out over a certain length or area, while point load refers to a load that is applied at a specific point. In the deflection formula, distributed load is represented by the variable w, while point load is not considered.

## Are there any assumptions made in the deflection formula?

Yes, there are a few assumptions made in the deflection formula. These include: assuming the rod/axlepipe is homogeneous, has a constant cross-sectional area, and is under elastic deformation. Additionally, the formula does not take into account any external forces or moments acting on the rod/axlepipe.

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