Development of Mini Universal Testing Machine

Abstract

The research work was on development of universal testing machine to determine the stress-strain of materials of maximum tension capacity not exceeding 500 N and extension of 100 mm maximum. The developed machine consists of mechanical frame bevel gear drive with wiper dc motor, instrumentation and motor control. The mechanical structure is made of two steel fixed columns of 340 mm in length and 22.05 mm in diameter. The columns can with stand 3.5 Ton load. The fixed crosshead and moving crosshead they attached with lock clamp pointing to each other. A dc wiper motor was used to drive moving crosshead via bevel gear system arrangement attached with 230 mm fine thread bolt with pitch 0.02 mm. The instrumentation is made of 100 mm active region long, 10 kΩ, linear potentiometer with analog-to-digital converter (ADS1115), load cell of 50 kg, load cell amplifier with 24 bits serial output, keypad, micro SD card shield, liquid crystal display (LCD) and switches for performance various operation. The motor DC drive consists of wiper motor dc, dc motor H-bridge bidirectional drive. The machine has maximum extension of 100.000 mm with resolution of 0.002mm and maximum applied force of 500.000 Nwith resolution of 0.001 N. The instrument was tested and performance evaluation was carried out the result obtained shows that force measuring unit and extensometer has correlation of 0.985 and 0.997 respectively also mean deviation is 0.00241 N and 0.000213 mm compared with available standard weight and vainer calliper respectively.