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Problem 1: Warm-ups a) Four strain gauges are bonded to a cylindrical bar as shown below. What signal is generated by each gauge when a small torque is applied to the bar? Positive = tension. (i) (ii) (!!!) (iv) (i) Positive Negative Zero Positive Positive Negative Zero Negative Zero (iv) Positive Negative Zero b) Your team has completed the design of a structural component and calculated the most critical safety factor. Which of the following factors, by itself, could lead to a change in the calculated safety factor? A new, previously unanticipated failure mode is identified. The manufacturing tolerances are changed. A new material is specified for the component. The component is deployed in a new environment with a higher cost of failure. ☐ New laws governing the safety of the component go into effect. c) The fatigue life of bolted joints depends on how much they are tightened. You have determined that by increasing the specified preload (σm) on a bolted joint by 20%, the stress amplitude σ will be reduced by 20%. Assuming σm and σa were roughly equal to begin with, Is this a good idea? Yes or No. d) Someone overtightened the bolted joint shown and now it's too tight to turn! Should you: ☐ heat up the assembly, or cool down the assembly to get it unstuck? e) Rank the four stress states shown below in order of increasing safety factor for the two failure criteria given. Assume the circle shown is the largest Mohr's circle for each stress state. Brass bolt and nut, a = 18E-6 1/K Steel plates a=11E-6 1/K

Problem 1: Warm-ups a) Four strain gauges are bonded to a cylindrical bar as shown below. What signal is generated by each gauge when a small torque is applied to the bar? Positive = tension. (i) (ii) (!!!) (iv) (i) Positive Negative Zero Positive Positive Negative Zero Negative Zero (iv) Positive Negative Zero b) Your team has completed the design of a structural component and calculated the most critical safety factor. Which of the following factors, by itself, could lead to a change in the calculated safety factor? A new, previously unanticipated failure mode is identified. The manufacturing tolerances are changed. A new material is specified for the component. The component is deployed in a new environment with a higher cost of failure. ☐ New laws governing the safety of the component go into effect. c) The fatigue life of bolted joints depends on how much they are tightened. You have determined that by increasing the specified preload (σm) on a bolted joint by 20%, the stress amplitude σ will be reduced by 20%. Assuming σm and σa were roughly equal to begin with, Is this a good idea? Yes or No. d) Someone overtightened the bolted joint shown and now it's too tight to turn! Should you: ☐ heat up the assembly, or cool down the assembly to get it unstuck? e) Rank the four stress states shown below in order of increasing safety factor for the two failure criteria given. Assume the circle shown is the largest Mohr's circle for each stress state. Brass bolt and nut, a = 18E-6 1/K Steel plates a=11E-6 1/K

Elements Of Electromagnetics
Elements Of Electromagnetics
7th Edition
ISBN:9780190698614
Author:Sadiku, Matthew N. O.
Publisher:Sadiku, Matthew N. O.
ChapterMA: Math Assessment
Section: Chapter Questions
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Problem 1: Warm-ups a) Four strain gauges are bonded to a cylindrical bar as shown below. What signal is generated by each gauge when a small torque is applied to the bar? Positive = tension. (i) (ii) (iii) (iv) (i) Positive Negative Zero (ii) (iv) Positive Negative Zero Positive Negative Zero Positive Negative Zero b) Your team has completed the design of a structural component and calculated the most critical safety factor. Which of the following factors, by itself, could lead to a change in the calculated safety factor? ☐ ☐ ☐ A new, previously unanticipated failure mode is identified. The manufacturing tolerances are changed. A new material is specified for the component. The component is deployed in a new environment with a higher cost of failure. ☐ New laws governing the safety of the component go into effect. c) The fatigue life of bolted joints depends on how much they are tightened. You have determined that by increasing the specified preload (σm) on a bolted joint by 20%, the stress amplitude σ will be reduced by 20%. Assuming σm and σa were roughly equal to begin with, Is this a good idea? Yes or No. d) Someone overtightened the bolted joint shown and now it's too tight to turn! Should you: ☐ heat up the assembly, or ☐ cool down the assembly to get it unstuck? e) Rank the four stress states shown below in order of increasing safety factor for the two failure criteria given. Assume the circle shown is the largest Mohr's circle for each stress state. Brass bolt and nut, a = 18E-6 1/K Steel plates a = 11E-6 1/K (j) (ii) (iii) (iv) Max. shear stress criterion: Most likely to fail Least likely to fail → Max. normal stress criterion: (assume Suc =2Sut) Most likely to fail Least likely to fail →
Transcribed Image Text:Problem 1: Warm-ups a) Four strain gauges are bonded to a cylindrical bar as shown below. What signal is generated by each gauge when a small torque is applied to the bar? Positive = tension. (i) (ii) (iii) (iv) (i) Positive Negative Zero (ii) (iv) Positive Negative Zero Positive Negative Zero Positive Negative Zero b) Your team has completed the design of a structural component and calculated the most critical safety factor. Which of the following factors, by itself, could lead to a change in the calculated safety factor? ☐ ☐ ☐ A new, previously unanticipated failure mode is identified. The manufacturing tolerances are changed. A new material is specified for the component. The component is deployed in a new environment with a higher cost of failure. ☐ New laws governing the safety of the component go into effect. c) The fatigue life of bolted joints depends on how much they are tightened. You have determined that by increasing the specified preload (σm) on a bolted joint by 20%, the stress amplitude σ will be reduced by 20%. Assuming σm and σa were roughly equal to begin with, Is this a good idea? Yes or No. d) Someone overtightened the bolted joint shown and now it's too tight to turn! Should you: ☐ heat up the assembly, or ☐ cool down the assembly to get it unstuck? e) Rank the four stress states shown below in order of increasing safety factor for the two failure criteria given. Assume the circle shown is the largest Mohr's circle for each stress state. Brass bolt and nut, a = 18E-6 1/K Steel plates a = 11E-6 1/K (j) (ii) (iii) (iv) Max. shear stress criterion: Most likely to fail Least likely to fail → Max. normal stress criterion: (assume Suc =2Sut) Most likely to fail Least likely to fail →
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