Figure 3 shows a schematic arrangement of an in-line tension meter, commonly used to sense the te...
Figure 3 shows a schematic arrangement of an in-line tension meter, commonly used to sense the tension T across a cable. The cable is routed through three pulleys (P1, P2 and Ps). As shown in Figure 3, only one of the pulleys (P2) is attached to the free end of a cantilever beam, sensorized with a set of four strain gauges in a full Wheatstone electrical configuration. The other two pulleys (P and P3) are 2 cm apart and 3. 2cm |pulleys (Pi,P2, P3) cable 450 1cm n mechanical ground strain gauges Figure 3 (a) Determine mechanical and electrical configurations of a full Wheatstone bridge which guarantees sensitivity to bending strain but not to axial strain and temperature. (5 marks) The four strain gauges forming the full bridge have a similar gauge factor G-2 and electrical resistance R- 350 2. Considering that the rated maximum power for each strain gauge is 0.25W, determine the maximum output voltage for a bending strain (b) S 0.1% of maximum rated measurement. (7 marks) (c) The pulley P2 only exerts a vertical pulling force F on the cantilever end-tip, and no bending moments. Determine the relationship between the pulling force F and tension T in the cable. 3 marks) (d) A commercial sensorized cantilever beam and its acquisition electronics are designed to provide an analogue electrical output, proportional to the pulling force. The output voltage is 0V when F-0 grams and 5V when the force is 780 grams. G) Determine the minimum detectable cable tension Tmin if the analogue voltage is acquired with a 10-bit analogue-to-digital converter. (5 marks) (i) Devise an experimental setup which allows deriving the experimental output- voltage vs. cable-tension characteristics of the whole system using a 200 grams basket and five 100 grams weights (all combinations, one to five weights). The basket is needed to support the weights. Draw on your answer book the voltage vs. weight plot you would expect from a similar experiment. (5 marks)
Figure 3 shows a schematic arrangement of an in-line tension meter, commonly used to sense the tension T across a cable. The cable is routed through three pulleys (P1, P2 and Ps). As shown in Figure 3, only one of the pulleys (P2) is attached to the free end of a cantilever beam, sensorized with a set of four strain gauges in a full Wheatstone electrical configuration. The other two pulleys (P and P3) are 2 cm apart and 3. 2cm |pulleys (Pi,P2, P3) cable 450 1cm n mechanical ground strain gauges Figure 3 (a) Determine mechanical and electrical configurations of a full Wheatstone bridge which guarantees sensitivity to bending strain but not to axial strain and temperature. (5 marks) The four strain gauges forming the full bridge have a similar gauge factor G-2 and electrical resistance R- 350 2. Considering that the rated maximum power for each strain gauge is 0.25W, determine the maximum output voltage for a bending strain (b) S 0.1% of maximum rated measurement. (7 marks) (c) The pulley P2 only exerts a vertical pulling force F on the cantilever end-tip, and no bending moments. Determine the relationship between the pulling force F and tension T in the cable. 3 marks) (d) A commercial sensorized cantilever beam and its acquisition electronics are designed to provide an analogue electrical output, proportional to the pulling force. The output voltage is 0V when F-0 grams and 5V when the force is 780 grams. G) Determine the minimum detectable cable tension Tmin if the analogue voltage is acquired with a 10-bit analogue-to-digital converter. (5 marks) (i) Devise an experimental setup which allows deriving the experimental output- voltage vs. cable-tension characteristics of the whole system using a 200 grams basket and five 100 grams weights (all combinations, one to five weights). The basket is needed to support the weights. Draw on your answer book the voltage vs. weight plot you would expect from a similar experiment. (5 marks)