tailieunhanh - Advances in Modern Woven Fabrics Technology Part 2

Tham khảo tài liệu 'advances in modern woven fabrics technology part 2', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Electro-conductive Sensors and Heating Elements Based on Conductive Polymer Composites in WoVen Fabric Structures 9 No. PARAMATER UM VALUE 1 Linear density of the filament g km 2 Diameter of the filament mm 3 Average width of the sensor cross section mm 4 Average thickness of the sensor cross section mm 5 Aspect ratio of the sensor width thickness - 6 Initial resistance of the sensor kfì Table 1. Sensor properties For insertion in conductive fibre based reinforcements like that woven using carbon multifilament tows the sensor was coated with Latex Abformmasse supplied by VossChemie so as to insulate the sensor from surrounding carbon tows. Prepared in this way the sensor with polyethylene substrate was tested again on MTS 1 2 tester under quasi static tensile loading at a constant test speed of 5 mm min. The same Keithley KUSB-3100 data acquisition module was employed for the purpose of voltage variation during tensile testing. This time a special set-up containing a Wheatstone bridge and an amplifier was used to measure unknown variable resistance of the sensor as a function of output voltage. As is obvious from curves presented in Fig. 2-a b and c the simple voltage divider circuit is not adequate for the measurement of resistance change in case of sensors developed here. These piezoresistive sensors produce a very small percentage change in resistance in response to physical phenomena such as strain. Moreover the output signal has considerable noise. Generally a bridge measures resistance indirectly by comparison with a similar resistance. Wheatstone bridges offer an attractive solution for sensor applications as they are capable of measuring small resistance changes accurately Wilson 2004 . Fig. 4 shows schematic diagram of the data acquisition module developed and used for data acquisition and its further treatment. Fig. 4. Schematic of instrumentation amplifier INA 101 connected to Wheatstone bridge 10 Advances in Modern Woven .