QUESTION 1 Use the Pb-Sn diagram below to answer the following questions. 350 327°C Liquid, L 300 250 232°C Pb-rich 200 solid (Pb) Sn-rich 183°C solid (Sn) 18.3% 61.9% 97.8% 3 150 100 50 Two phase: (Sn) + (Pb) 10 20 30 40 50 60 70 80 90 100 Pb Sn wt.% Sn (a) What are the values of the state variables (composition and temperature) at constitution point 1? (b) Mark the constitution points for Pb-60wt% Sn and Pb-20wt% Sn alloys at 2500C. What phases are present in each case? (c) The alloy at constitution point 1 is cooled very slowly to room temperature, maintaining equilibrium. At which temperatures do changes in the number or type of phases occur? What phases are present at constitution points 2 and 3? (d) The alloy at constitution point 4 is cooled slowly to room temperature. Identify the following: (i) the initial composition, temperature and phase(s); (ii) the temperature at which a phase change occurs, and the final phase(s). Temperature, T (°C)
Design Against Fluctuating Loads
Machine elements are subjected to varieties of loads, some components are subjected to static loads, while some machine components are subjected to fluctuating loads, whose load magnitude tends to fluctuate. The components of a machine, when rotating at a high speed, are subjected to a high degree of load, which fluctuates from a high value to a low value. For the machine elements under the action of static loads, static failure theories are applied to know the safe and hazardous working conditions and regions. However, most of the machine elements are subjected to variable or fluctuating stresses, due to the nature of load that fluctuates from high magnitude to low magnitude. Also, the nature of the loads is repetitive. For instance, shafts, bearings, cams and followers, and so on.
Design Against Fluctuating Load
Stress is defined as force per unit area. When there is localization of huge stresses in mechanical components, due to irregularities present in components and sudden changes in cross-section is known as stress concentration. For example, groves, keyways, screw threads, oil holes, splines etc. are irregularities.
Please help for d. Both i) and ii)
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