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 ?