# Stress Strain Curve: Converting Psi and In/In to MPa and mm/mm

• shinoy
In summary, the conversation discusses converting a stress strain curve from strain (in/in) and stress (Psi) to stress (MPa) and strain (mm/mm). The stress can be converted by multiplying by 0.00689475729, but the strain, being a unitless quantity, does not need to be converted.
shinoy
Hi All,

I have a stress strain curve, which have strain(in/in) on x-axis and stress in Y axis(Psi).
Here I want to conver the curve to stress(MPa) and strain (mm/mm). I know that Psi can be converted by multiplying the digit by 0.00689475729. But in this case I need to change the strain value? As strain is a unitless quantiy I can use as it is?

Hi shinoy, welcome to PF.

You are correct; strain has no units, so it doesn't need to be converted (equivalently, it can be labeled mm/mm, yard/yard, or anything you like).

Mapes said:
Hi shinoy, welcome to PF.

You are correct; strain has no units, so it doesn't need to be converted (equivalently, it can be labeled mm/mm, yard/yard, or anything you like).

Hi Mapes,

## 1. How do I convert stress values from psi to MPa?

To convert stress values from psi to MPa, you can use the following formula: MPa = psi * 0.00689476. This means that you need to multiply the psi value by 0.00689476 to get the equivalent value in MPa.

## 2. Is there a conversion factor for converting strain values from in/in to mm/mm?

Yes, there is a conversion factor for converting strain values from in/in to mm/mm. The conversion factor is 25.4. This means that you need to multiply the in/in value by 25.4 to get the equivalent value in mm/mm.

## 3. Why do we need to convert stress and strain values?

We need to convert stress and strain values in order to have a standardized unit of measurement. This allows for easier comparison and analysis of data from different sources. Converting to a common unit also helps in understanding and interpreting the results accurately.

## 4. Can stress and strain values be converted back and forth between different units?

Yes, stress and strain values can be converted back and forth between different units. As long as the conversion factors are applied correctly, you can convert from psi to MPa and vice versa, and from in/in to mm/mm and vice versa.

## 5. Is it important to include units when presenting stress-strain data?

Yes, it is important to include units when presenting stress-strain data. Units provide context and help in understanding the values being presented. Additionally, including units ensures that the data is accurate and consistent.

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