Electronic – measure torque accurately by an electrical or electronic method

current measurementpower-measurementstepper motortorque

I am a Btech. student from India. We have been given a project in which we have to design a micro-torsion testing device.

We are planning to clamp the specimen and rotate one end by fixed angles using a stepper motor while measuring the torque for given deflection. The shear modulus and the angle/torque at which the specimen fails has to be found out.

The most accurate way to do this seems to be using torque sensors but since our budget is small ( Rs. 10k – arnd 150 dollars) we cant use this. Another way we had in mind was to measure the current drawn by the motor and find out the corresponding torque. But this seems to be prone to errors. Can someone help me out with this ?

Best Answer

Fix a lever of a precise known length to the specimen and add calibrated masses. Measure the deflection with a dial gauge.

Perpendicularity might be a concern and could be addressed with geometry... However, the error that introduces is probably small compared to other sources. The sources of errors may well be worth checking. I know that for the dynamometers we used on engines, pumps etc there was no correction but the beam was usually corrected back to a given calibrated zero point.

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