Machine Design

Project problem: A pressure vessel is widely used in industry, i.e. power plants, oil and gas establishments and the like. The pressure vessel is a container that holds gases, vapor or liquids above the ambient pressure. The figure below shows a pressure vessel attached to L-shaped support via links AC-BC and bolts (assume the bolts act as pins). The L-shaped support and links are made of steel (you can assume carbon content 2%). The material of the pressure vessel is stainless steel 304. The internal pressure is 8 MPa excreted by the air at 30°C. The internal diameter of the vessel is given as I m, and the length of the pressure vessel is 2.5 m. 5. Design the minimum diameter (D) of the L-shaped support.

A 1-in-diameter solid round bar is made of AISI 1040 CD steel (sy= 71 kpsi, su = 85 kpsi ). It is operating at a temperature of 300°F, and is subjected to a purely reversing torque of 2000 lbf.in. Estimate the number of cycles to failure if the expected reliability is 99%. Redo the solution for a reversing torque of 8500 lbf.in. Note: The Von Mises stress for pure torsion would be o' = √37²

The solid shaft shown below is in equilibrium, supported at two bearings A and B. The pulleys C and D have diameters in the ratio 3:2. T₁ = 1000 N, T₂ = 500 N and T3 = 1500 N. The diameter of the shaft is 50 mm and yield strength sy = 400 MPa. The bearings do not exert any moments or axial forces on the shaft. a. If a factor of safety (n) of 3 is desired based on Maximum Shear Stress (MSS or Tresca) criteria, find the diameter of pulleys C and D. b. If n = 3 is desired based on the Distortion Energy Theory (DET or von Mises criteria), find the diameter of pulleys C and D.

In the figure above, the diameter of pulleys C and D are given to be 600 mm and 400 mm, respectively. T₁ = 1000 N₂ T₂ = 500 N and T3 = 1500 N. But in addition to the force on the pulleys, a compressive axial force of 100 kN is acting on both ends of the shaft. The shaft is made from a brittle material with an ultimate tensile strength sur that is half of its ultimate compressive strength suc. If desired n = 2 for the shaft, find the minimum required Sut and Suc- a. Use Maximum Normal Stress Theory b. Use Brittle Coulomb-Mohr Theory c. Use Modified Mohr Theory

A solid round bar with diameter of 2.75-in has a groove cut to a diameter of 2.5-in, with a radius of 0.125-in. The bar is not rotating. The bar is loaded with a repeated bending load that causes the bending moment at the groove to fluctuate between 10 kip.in and 30kip.in and a reversing torque of +10kip.in. The bar is hot-rolled AISI 1095 (s,, = 66 kpsi, Sut = 120 kpsi), but the groove has been machined. Determine the number of cycles to failure.

The rotating shaft shown in the figure is machined from AISI 1040 CD steel (s = 490 MPa, Sut 590 MPa). It is subjected to a traverse force of F = 8 kN between the supports. The system designed to be operated at a temperature of 120°C with a reliability of 99%. Estimate the number of cycles. All dimensions are in mm. Assume all fillets are 3mm in radius.

Bolt Design The connection shown carries an external load P. The bolts are M10 fine thread, Grade 8.8 (rolled thread). The plate thickness L = 50 mm. The bolts are made of steel (E = 207 GPa) and the parts of cast iron (E = 100 GPa). Assume properties are guaranteed minimum values. Operating temperature is 30°C. Determine the bolt stiffness (ignore the effect of the thread). Determine the required initial preload on the bolt for a reusable bolted joint. Determine the load P for the joint to separate. Determine the tensile force on the bolt when load P = 10 kN.

Design a single-reduction, spur gear-type speed reducer with all components. Specify the two gears, two shafts, four bearings, and a housing (with fasteners). This gearbox must fit into the condition shown below: A water turbine transmits 50 kW of power to a pair of gears at 4500 rpm. The output of the gear pair must drive an electric power generator at 3600 rpm. The center distance for the gear pair requires not to exceed 150 mm. Project Requirements: 1. Design the gearbox. Show all calculations, selection processes, and detailed analysis. 2. Make detailed component drawings for two shafts and the housing. 3. Demonstrate an assembly drawing for the gearbox. Submission: 1. A completed project report with your design, analysis, and drawing. Save your report as a PDF file. 2. A zip file includes all your CAD drawings.

Fatigue Design A cold drawn AISI 1020 CD steel link is subjected to axial loading (that fluctuates from 0 to 2 kN) by pins that go through the holes. Determine the critical tensile area (mm²) through the hole. Determine the mean and alternating axial stresses. Determine the safety factor against fatigue failure using the Soderberg failure criteria given:

Bearing Design A 25 mm deep groove ball bearing "6205" carries a combined load of 2 kN radially and 3 kN axially at 1500 rpm. Determine the equivalent radial load. Determine the dynamic load rating of the bearing. Determine the L₁0 life of the bearing in hours.