assistance with part 8
Part1: ● What is the force transducer calibration equation using the measured force transducer dimensions, strain gauge properties, and signal path gain values? How does the equation compare to the designed calibration? (see homework) F=32103.17 Vrio + 1505124.48 N (Measured Transducer Calibration Equation) F_Design=32561.872 VRio - 651237.44 (Designed Force Transducer Equation) The measured equation has a gain which close to the designed equation’s gain, the measured gain is 98.69% of the designed gain, the measured offset has a difference of 331% of the designed offset, more than the designed offset. ● How will this difference from the designed equation affect your measurements? The designed gain is larger than the measured gain. The significantly increased offset is so much larger than the gain difference that all force values read by the transducer will be significantly larger than the designed equation, within the voltage range of this experiment. ● What components are responsible for discrepancies from the design? Justify with data and comparison to design values. The discrepancy in the gain is small, and can largely be attributed to the difference in amplifier gain, as the amplifier gain is 99.3% of the designed amplifier gain, with the total gain being 98.69% of the total designed gain. The difference in gain only accounts for 230 N of the difference. The primary cause of discrepancy in the offset stems from the voltage offset in the voltage vs strain gauge resistance which accounts for +7925387.33 N of offset in the measured equation. Part2: ● Create a plot of your calibration data. ● What is the calibration equation for the force transducer? What is the precision (K=2, 95.4% prediction interval) of the force transducer? The calibration equation is 34.46*x – 2.511 RMSE = 0.4552 kN The precision is +/- (2* 0.4552) = +/- 0.9104 kN; Thus, the prediction interval is (34.46*x - 2.511 +/- 00.9104) kN ● How does this calibration compare to the derived calibration in Part 1? If there are large discrepancies, which component could be the source? Part3: ● Create a plot of your calibration data. ● What is the calibration equation of the position sensor? What is the precision (K=2, 95.4% prediction interval) of the position sensor? ● Save the data from the force transducer and the position sensor. Plot deformation of the rig versus the applied force. ● Determine the relationship of the measured deformation of the rig as a function of the applied force. ● How will the rig deformation affect your results during stress-strain testing? When and how should you compensate for it in your results? Part4: ● Save the data from the force transducer and the position sensor. Plot force versus change in length of the sling. ● What is the ultimate tensile force of the sling, including the measurement uncertainty from the force transducer? How does it compare to the manufacturer's stated rating? Figure X shows that the ultimate tensile force of the climbing sling is approximately 30.5 kN, and after including measurements of uncertainty, the range is approximately [29.6, 31.4] kN. The sling is rated for 27 kN. This means that the ultimate tensile force of the climbing sling is measured to be at least 2.6 kN above its rating, which is percent error of 9.63%. Part 5: Part 6: ● Plot a comparison of the force versus displacement profiles of the bolts. ● Determine the ultimate strength (force) for each bolt. How did the bolts perform compared to the specifications in the lab resources? Figure X shows that the alloy steel, grade 8, and grade A bolts had an ultimate tensile force of 23.264 kN, 22.633 kN, 10.896 kN respectively with a calculated uncertainty of 0.911 kN. Table X shows that the manufacturers rated the bolts having an ultimate tensile force of 24.047 kN, 21.218, 8.487 respectively. So, it was found that, within the range of uncertainty, the alloy steel bolt was within the manufacturer’s rating while the grade 8 and grade A bolts had a minimum percent error of 2.38% and 17.7%, respectively. Part 7: ● Plot the force versus displacement. Label important values and material properties. ● Plot the stress versus strain. Label important values and material properties. ● Determine from the stress-strain profile, the Young’s modulus, yield stress, strain at yield, ultimate stress, and the strain at failure for the test specimen. How do your results compare to the published values for Aluminum 6061-T6 (www.matweb.com)? You should also compare the measured values of force and displacement to those calculated from the published values. Part 8: ● How does the precision of the force transducers compare to the climbing sling, bolts, and dog bone measurements? What does this tell you about the suitability of the force transducer for testing the climbing sling, bolts, and dog bone? (There may be variations between application and material properties) ● How does the precision of the position sensor compare to the climbing sling, bolts, and dog bone measurements? What does this tell you about the suitability of the position sensor for testing the climbing sling, bolts, and dog bone? (There may be variation between application and material properties)? ● What do you believe is the cause of the discrepancies observed in the material certification, the difference in the signal path and force transducer equations, and/or the precision of the devices? What in your data leads you to this conclusion? ● Which results do you believe are valid from your testing? Justify with test data, sensor prediction intervals, and expected material properties. What types of tests and materials is the rig currently suitable for? ● What improvements, if any, are needed in the testing rig? What recommendations would you make to implement these and why? Appendix Figure X: Tensile Force (N) vs Change in Length (mm) of Climbing Sling Figure X: Tensile Force (N) vs Change in Length (mm) of Alloy Steel, Grade 8, Grade A Bolts Table X: Manufacturer’s Rating of Alloy Steel, Grade 8, Grade A Bolts