Creating Web Pages in your Account – Computer Action Team



ME 314 – Spring 2019 – Midterm Exam #2Name:____________________Open books, notes, laptops, phones. No electronic or other communication with other people during the exam. Time allotted 100 minutes. Unless otherwise specified, all materials are steel. Do not separate the pages. Write your name on all pages. Circle only one answer. If the answers are off by more than +/- 2 percent, circle “None of these”. Each question has 5 points unless otherwise specified.A plate made of AISI 1010 is welded to base plates made of AISI 1020. The weld electrode is E60. Calculations show a critical shear stress of 5 ksi. The factor of safety guarding against static failure is: a) 2.82b) 3.30c) 3.72d) 4.41e) None of theseA round tube of diameter 2 inches is welded to a wall and subjected to a tensile force of 5000 lbs as shown. The weld rod is E60. The weld leg is 0.25 inches. What is the factor of safety guarding against weld metal yielding as a result of this force?a) 1.62b) 2.48c) 3.38d) 4.13e) None of theseA square tube of side 2 inches is welded to a wall where only the top and bottom edges are welded. The weld leg is 0.25 inches and the weld electrode is E60. The figure shows that the tube is subjected to a bending force of 500 lbs acting at a distance of 12 inches. Ignoring direct shear stresses, what is the factor of safety guarding against yielding of the weld metal?a) 1.6b) 2.2c) 3.1d) 4.8e) None of these A round tube of diameter 2 inches is under pure torsion of 8000 in-lb as shown in the figure. The tube is welded to the post all-around using a E70 electrode. If the weld leg is 0.25 inches, what is the factor of safety guarding against yielding?a) .82b) 1.64c) 2.91d) 3.83e) None of these A welded beam is under direct tension, bending, and torsional moments. Calculations show that the shear stress resulting from direct tension is 10 ksi, from torsion is 15 ksi, and the shear stress resulting from bending is 20 ksi. What is the combined critical shear stress in the weld in ksi?a) 22b) 26c) 32d) 36e) None of theseThe nominal critical shear stress in a weld metal is calculated to fluctuate between -3 ksi and 3 ksi (i.e. fully reversed stress). A stress concentration factor is consistent with the “End of parallel fillet weld”. The weld electrode is E100. The weld surface is similar to a Hot Rolled surface. What is the factor of safety guarding against eventual fatigue failure for the weld metal?a) 1.55b) 1.92c) 2.46d) 2.94e) None of theseA helical compression spring is to have an installation length of 3 inches. The spring is to have a length of 2 inches at maximum working force. The spring forces are to be 10 lbs at installation length and a maximum working force of 50 lbs. If the shut or solid (fully compressed) length of the spring is 1.5 inches, what force (in lbs) compresses the spring to solid length? a) 55b) 60c) 65d) 70e) None of theseA helical compression spring is made of HD (A227) and has a spring constant of 4.25 lbs per inch. If the wire diameter is 0.1 inch and the coil mean diameter is 1.5 inch, what is the number of active coils:a) 8b) 9c) 10d) 11e) None of theseA helical compression spring is made of music wire with a wire diameter of 0.15 inch and mean coil diameter of 1.5 inch. The solid force for this spring is 25 lbs. The shear stress in ksi when the spring is closed shut is:a) 32.1b) 41.6c) 57.5d) 61.7e) None of theseA helical compression spring is made of music wire with a wire diameter of 0.1 inch and mean coil diameter of 1 inch. The spring is not set-removed. The maximum working force is 12 lbs. What is the factor of safety guarding against set (yielding) at the maximum working force?a) 3.65b) 4.83c) 5.68d) 6.34e) None of these[10 points] A helical compression spring is made of music wire with a wire diameter of 0.1 inch and mean coil diameter of 1 inch. The spring is subjected to fluctuating loads. Calculations show that the spring shear stress fluctuates between 20 and 60 ksi. The factor of safety guarding against fatigue failure from Zimmerli data using the Goodman criteria is:a) 1.62b) 2.33c) 3.71d) 4.27e) None of theseA helical compression spring with a wire diameter of 0.125 inch has a free length of 4 inches and a spring constant of 10 lbs/in. The number of total coils for this spring is 12. The spring ends are squared and ground. The maximum spring force is 20 lbs. The fractional overrun to closure is:a) 0.15b) 0.25c) 0.35d) 0.45e) None of theseIn a ball bearing selection application the radial load is 320 lbs. The load application factor is 1.4 and the application life is 170 million cycles. The desired reliability is 95%. The bearing is to be 02 series deep groove. The bore diameter (in mm) of the smallest adequate bearing from Table 11-2 is:a) 15b) 17c) 20d) 25e) None of theseIn a ball bearing selection application the radial load is 370 lbs. The load application factor is 1.4 and the application life is 30 million cycles. A 15 mm bore deep groove bearing has been selected from Table 11-2. The reliability of this bearing is closest to:a) 90%b) 93%c) 95%d) 97%e) 99%[10 points] A Series-02 deep groove is subjected to 300 lbs of radial load and 100 lbs of thrust load. The bearing bore size is 20 mm. The bearing inner ring rotates. The equivalent radial load for this bearing (in lbs) is:a) 216b) 274c) 331d) 406e) None of theseA ball bearing is selected for the design radial load of F=1000 lbs and design life of L= 30 million cycles and a reliability of 90%. If the bearing is subjected to an actual radial load of 2000 lbs instead, for the same 90% reliability the bearing life (in million cycles) would be reduced to:a) 1.25b) 3.75c) 4.50d) 5.75e) None of theseA gearbox uses 4 identical bearings. If each bearing is designed to have 98% reliability, what is the reliability of the gearbox bearing collection is closest to: a) 90%b) 92%c) 94%d) 96%e) 98%A cylindrical roller bearing is subject to a radial force of 50000 N. The application factor is 1.5. The desired reliability is 90%. The application life is 50 million cycles. The catalog available for this bearing lists the bearing capacities at 90 million cycles. The minimum capacity (in KN) required for this application for selecting the bearing from this catalog is closest to:a) 26b) 43c) 63d) 76e) 85 ................
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