MECH3110 Mechanical Engineering Design 2

TASKS
Part 1

1. Design the welded connection between the tower and the base plate. The lower section of the tower is constructed from 5 mm thick plate with a yield strength of 350 MPa. If the weld leg length exceeds 5 mm, appropriate gussets between the tower and base plate need to be added. Verify the effects of these gusset on the calculated size of the weld.

2. Undertake design checks on each shaft in the gearbox for “worst case” loading conditions.

a) Construct shear force and bending moment diagrams for each shaft. For this analysis, assume the inertias of the relevant system components are significant. Hint: Refer to the Appendices in Australian Standard AS1403 for worked examples of this type of problem.

b) Apply both Soderberg's method and the approach outlined in AS 1403 – 2004 Design of rotating steel shafts, to calculate the safety factor based on stress for each shaft in the gearbox. The Australian Standards are available through the UON library.

3. Present your design calculations in “normal” assignment format ensuring you highlight the information requested.

Part 2

4. Undertake a detailed design check on all gear teeth in the gearbox assuming infinite gear life is required. Determine the minimum width of the gears in the drive for 99% reliability based on both bending fatigue and surface fatigue failures. Assume the gears are made using a high-quality hobbing process and have been case hardened to 450 Bhn. The gears in the reduction box are lubricated by oil.

5. Determine the brake pretension required to bring the rotor speed from 320 rpm to 0 rpm in half a second. Determine the temperature rise in the brake rotor at the end of this braking event.

6. Assuming light duty (Series 200 – Table 14.2 of Juvinall and Marshek) radial ball bearings determine the corresponding bearing lives for all shafts in hours for 90% and 99% reliability. Base all bearing bore sizes on the nominated shaft diameters and base life calculations on steady-state turbine generating conditions, i.e., neglect braking loads.

7. Present your solutions in a Professional Report that summarises all findings. Your report should cater to the needs of both Management and a fellow Engineer. Please note that all design calculations should be included as handwritten notes in the appendix and referenced where necessary. Additional mark will not be awarded for typed calculations.