Understanding Moment of Inertia and Bending Stress in Physics Forums

In summary, the conversation is about a new member joining a physics forum and asking for help with understanding the moment of inertia. They are confused about the difference between using 1/3 bh^3 and 1/12 bh^3 and how to determine if the neutral axis passes through the centroid or center of gravity.
  • #1
falah alajmi
6
0
hi all ,

I am a new member in physics forums and I hope I can help and get benefit from this forums .

I would ask anyone knows about the moment of inertia cos i have not study it before and I have to know it to solve a bending stress problem ..

when I used the moment of inertia for rectangle as 1/3 bh^3 and when I use it as 1/12 bh^3

as I now I use the first one when the neutral axises pass through the centroid and the second one when it not pass through the centroid .. but how can I know if the neutral axises pass through the centre of gravity or not ?


sincerely
falah alajmi
 
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  • #2
there is no one knows the answer
 

What is bending stress?

Bending stress, also known as flexural stress, is a type of stress that occurs when an object experiences a force that causes it to bend or deform. It is a measure of the internal forces within an object that resists its bending.

What causes bending stress?

Bending stress is caused by an external force acting on an object, such as a weight or a load. This force creates a moment, or a rotational force, that causes the object to bend or deform. The magnitude of the bending stress depends on the amount of force applied, the geometry of the object, and the material properties of the object.

How do you calculate bending stress?

The formula for calculating bending stress is σ = (Mc)/I, where σ is the bending stress, M is the bending moment, c is the distance from the neutral axis to the outermost point on the object, and I is the moment of inertia of the object. This formula can also be simplified to σ = (F*L)/I, where F is the force applied and L is the length of the object.

What are the effects of high bending stress?

High bending stress can lead to permanent deformation or failure of an object. This can result in cracks, fractures, or structural collapse. It can also cause fatigue failure, where the object fails after repeated stress cycles, even if the stress is below the yield strength of the material.

How can bending stress be reduced?

To reduce bending stress, the object's geometry and material properties can be optimized to distribute the stress more evenly. This can be achieved through design changes, such as adding reinforcement or changing the shape of the object. Using a stronger material or increasing the object's cross-sectional area can also reduce bending stress.

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