With couple of threads before,

1. Now I can calculate strain from voltage read by adc.

e = (dR/R)/GF , e = strain , dr = change in resistance & GF is gauge factor, R= strain gauge resistance unstrained.

we can calculate:
dR/R = -4Vr / (1 + 2Vr), where Vr = Vo / vsupply

This way with known voltage read I can calculate strain applied.


1. Next stage: How to calculate load in kg from known strain.

 

This question has been already been answered a number of times by members.

Use calibrated weights and draw a plot of weight versus mV output.

Why do you creating new threads for the same topic.?

 

With couple of threads before,

1. Now I can calculate strain from voltage read by adc.



This way with known voltage read I can calculate strain applied.


1. Next stage: How to calculate load in kg from known strain.

You must first construct some sort of load cell. Have you done that yet? Load cells are quite basic in theory. But still not something you build home at your workbench. Most often they use 2 or 4 strain gauges. You seams to be happy with using just one. Somehow it looks like you are hoping for somebody to come alone with a magic wand, and do some magic to create your load cell. And then this do not happen you create a new thread(sigh!).

 

As I said in your other thread, strain is related to load by the modulus of elasticity of a material. Strain is essentially a change in size due to a load. You fasten your strain gauge to something, deform it and calculate the load by knowing how much it deforms.