How to convert force displacement curve to stress strain curve

In summary, a force displacement curve shows the relationship between applied force and resulting displacement, while a stress strain curve shows the relationship between applied stress and resulting strain. It is necessary to convert a force displacement curve to a stress strain curve in order to accurately compare different materials. This conversion requires knowledge of the material's dimensions, geometry, applied force, and resulting displacement. The conversion is calculated using the material's cross-sectional area, original length, applied force, and displacement data. However, there are limitations and assumptions, such as the material being homogeneous and having linear elastic behavior, as well as being subjected to uniaxial stress.
  • #1
fishfried
1
0
Hi
i need help with this conversion as i am unsure how to approach this.
I have obtained a force vs displacement curve from a Hounsfield materials testing machine, and would like to know how to convert this to a stress vs strain curve.
Thanks
 
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  • #2
How are stress and strain define? (show us some equations)

This is a pretty simple problem, and I think if you look at the equations, you will be a lot closer to understanding what you need to do.

-Kerry
 
  • #3


Converting a force displacement curve to a stress strain curve requires knowledge of the material's properties and the equations that relate force, displacement, stress, and strain. Here are the steps you can follow to convert the curve:

1. Determine the cross-sectional area of the material: The cross-sectional area is needed to calculate stress, which is defined as force per unit area. You can measure the area directly or calculate it using the dimensions of the material.

2. Calculate stress: Stress is calculated by dividing the force by the cross-sectional area. This will give you stress values for each point on the force displacement curve.

3. Determine the original length of the material: The original length is needed to calculate strain, which is defined as the change in length divided by the original length.

4. Calculate strain: Strain is calculated by dividing the change in length (displacement) by the original length. This will give you strain values for each point on the curve.

5. Plot stress vs strain: Once you have calculated stress and strain values for each data point on the force displacement curve, you can plot them on a graph to obtain the stress strain curve.

It is important to note that the conversion from force displacement to stress strain assumes that the material is linearly elastic, meaning that it follows Hooke's law. If the material exhibits non-linear behavior, such as plastic deformation, the conversion may not accurately reflect the material's properties. In this case, further analysis and testing may be needed to obtain a more accurate stress strain curve.
 

1. What is the difference between a force displacement curve and a stress strain curve?

A force displacement curve shows the relationship between the applied force and the resulting displacement or deformation of a material. On the other hand, a stress strain curve shows the relationship between the applied stress and the resulting strain or change in length of a material.

2. Why is it necessary to convert a force displacement curve to a stress strain curve?

A force displacement curve does not take into account the size or geometry of the material being tested, making it difficult to compare results between different materials. Converting it to a stress strain curve allows for a more accurate comparison of the mechanical properties of different materials.

3. What information is needed to convert a force displacement curve to a stress strain curve?

In order to convert a force displacement curve to a stress strain curve, you will need to know the dimensions and geometry of the material, as well as the applied force and the resulting displacement at various points during the testing process.

4. How is the conversion from force displacement curve to stress strain curve calculated?

The conversion from force displacement curve to stress strain curve is calculated using the material's cross-sectional area and original length, as well as the applied force and displacement data. The stress is determined by dividing the force by the cross-sectional area, and the strain is determined by dividing the displacement by the original length.

5. Are there any limitations or assumptions when converting a force displacement curve to a stress strain curve?

Yes, there are some limitations and assumptions when converting a force displacement curve to a stress strain curve. This conversion assumes that the material is homogeneous and has a linear elastic behavior. It also assumes that the material is subjected to uniaxial stress, meaning that the force is applied in one direction and the material is free to expand or contract in the other directions.

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