Internal stress in a wall at object impact

[Aragorn49]

Homework Statement

In the past months I've been working on a work calculating the behavior of a wall at an object impacting into it. I thought I have made it by knowing the impact force and the pressure it makes but then I realized that to fully complete my work I have to somehow calculate the internal stress in the wall. So to sumarize it, I know the impact force of the object hitting the wall and I also know the dimensions of both the wall and the object. What I'm trying to find out is what form of stress does occur inside the wall after object impact. Is it shear stress or maybe shear stress + another stress? How can I calculate this stress?

Homework Equations

When studying about the individual stresses I found that there is always the equation of the stress being equal to F/A. I know F but I don't know what the A is. i know the dimensions of the wall but I don't know how to characterize what is the A and what isn't.

The Attempt at a Solution

Well, I have studied the info I could find about the individual stresses but I still don't understand which stress to apply and what to consider the area (A) or cross section of the impact. I became pretty much confident that at least partially the stress is shear but there could be more stresses. I also don't know how to calculate a possible combined stress.

Thank you for reading my question
Aragorn49

 

[KataKoniK]

Dear Aragorn49,

Thank you for sharing your question and progress on your project. It sounds like you are on the right track in considering the impact force and dimensions of both the wall and the object. However, to fully understand the internal stress in the wall, you will need to also take into account the material properties of the wall and how it responds to external forces.

In order to calculate the internal stress in the wall, you will need to use the equation you mentioned, where stress (σ) is equal to force (F) divided by the cross-sectional area (A). The cross-sectional area refers to the area of the wall that is being impacted by the object. This area will depend on the shape and dimensions of the object and the angle at which it impacts the wall. For example, if the object is a sphere and impacts the wall head-on, the cross-sectional area would be the area of a circle with the same diameter as the sphere.

In terms of the type of stress that occurs inside the wall, it will likely be a combination of different types of stress, including shear stress, compressive stress, and tensile stress. The specific type and magnitude of stress will depend on the material properties of the wall, such as its strength and elasticity.

To calculate the combined stress, you can use the principle of superposition, which states that the total stress at any point is equal to the sum of the individual stresses acting at that point. This means that you can calculate the individual stresses caused by the impact force and then add them together to get the total stress.

I hope this helps guide you in your research and calculations. Good luck with your project!