6MA034 Machine Design & Reliability Assignment Task Semester 1 | UoW

6MA034 Learning Outcomes

• To be able to analyse and appraise key rapid manufacturing processes and associated materials characteristics used for component manufacture.
• To be able to assess sustainability issues and the environmental impact of component manufacture.
• To be aware of design for manufacture issues, including assembly, disassembly, maintenance and disposal.

6MA034 Task 1. 

Part A 

Using the force flow concept, locate the critical sections and surfaces in the members shown in Figure 1. Write your simplifying assumptions and describe with the aid of sketches, describe your analysis.

Part B 

What are the various methods of failure prediction in knuckle joints? What are the empirical data that can be used for the Knuckle Joint? Design a knuckle joint to transmit 125 kN. The design stresses may be taken as 75 MPa in tension, 60 MPa in shear, and 150 MPa in compression.  11 Marks

Task 2. 

A bracket is bolted to a column by 6 bolts of equal size as shown in Figure 2. It carries a load of 50 kN at 150 mm from the centre of the column. If the maximum stress in the bolts is to be limited to 150 MPa, determine the diameter of the bolt. The distance between to centres of the bolts in vertical and horizontal directions is 75 mm.

Task 3. 

A bracket, as shown in Fig. 10.39, carries a load of 40 kN. Calculate the size of the weld if the allowable shear stress is not to exceed 80 MPa. 

Task 4 

A cold-drawn steel rod of circular cross-section is subjected to a variable bending moment of 565 N-m to 1130 N-m as the axial load varies from 4500 N to 13,500 N. The maximum bending moment occurs at the same instant that the axial load is maximum. Determine the required diameter of the rod for a factor of safety of 2. Neglect any stress concentration and column effect. Assume the following values: 

Ultimate strength = 550 MPa 
Yield strength = 470 MPa 
Size factor = 0.85 
Surface finish factor = 0.89 
Correction factors = 1.0 for bending 
                               = 0.7 for axial load 

The endurance limit in reversed bending may be taken as one-half the ultimate strength. 20 Marks

Task 5 

A simplified version of the transmission is represented in Figure 5-a. The engine is delivering a torque T = 340 Nm to the transmission, and the transmission is in low gear with a ratio R = 2.778. (For this problem, consider R to be a torque ratio, Tout/Tin. To the degree that friction losses are present, the speed ratio would have to be slightly greater.) The three major parts of the transmission are shown in Fig. 5-b and Fig. 5- c. 

Diameters of the gear wheels are DA 60 mm, DB 100 mm, DC = 60 mm and DD = 100 mm. Input gear A rotates at engine speed and drives countershaft gear B. Countershaft gear C meshes with main shaft output gear D. (The construction of the main shaft is such that the input and output rotate about a common axis, but the two halves are free to rotate at different speeds.) The main shaft is supported in the housing by bearings I and II. Similarly, the countershaft is supported by bearings III and IV. Determine all loads acting on the components shown in Fig. 5-band Fig. 5-c, thus representing them as free bodies in equilibrium. Suppose that the forces acting between mating gear teeth are tangential.