Question

× HW-2. Mech Behav. Sp19.docx HWI Prob I: (Textbook problem 1.25) Two parts have been made of the same material, but one was formed by cold working and the other by hot working. Explain the differences in mechanical behavior and surface properties you might expect to sec Prob 2: (Textbook problem 1.29) What is the significance of the fact that such metals as lead and tin have a recrystallization that is about room Prob 3: (Textbook problem 2.17) Why does the fatigue strength of a specimen depend on its surface finish? Prob 4: (Textbook problem 2.28) If a metal tension-test specimen is pulled and broken rapidly, where would the temperature be highest, and why Prob 5: (Textbook problem 2.37) A paper clip is made of wire 0.7 mm in diameter. If the original material from which the wire is made is a rod 25 mm in diameter, calculate the longitudinal engineering and true strains that the wire has undergone during processing Prob 6: (Textbook problem 2.45) A cable is made of two strands of different materials, A and B, and cross sections as follows For material A. K = 60,000 psi, n 0.5A。= 0.6 im, For material B, K = 30, 000 psi, n = 0.5M-0.3 in: Calculate the maximum tensile force that this cable can withstand prior to necking. Prob 7: Define the term anisotropy in the context of mechanical properties. What is plastic anisotropy and provide an example of anisotropy Prob &: Give an example of a manufacturing process which is used to improve the fatigue life of shafts and briefly explain how it works and how does it result in the improved performance Prob 9: Starting with rods of diameter 3.5 in, it is required to manufacture a total length of 1000 in of 2.3 in diameter wire by stretching. Assuming no waste, what should be the length of starting stock? If the material behavior - ksi at room temperature, can the process be done in one step? If not suggest a solution. Open With Print

Answer 1

Prob 1 orking material is formed belovo Recrystaliization dtericl -fiming hakea in cold oking masenial form temperature r、hereas in hot work i ng m place above Recrystalli zation temp which caujes changes in giain structure , grain sizes folle voing are he differences yo» can abseue Cold worcing D Duch lity ll de D srrength will increase D Strengtn aill (S Retter dimensional Hct working duchliy will increoye ToleranceJ Surface nish obtoined Poor sarface finish wi )I be obtuned will be excellent ohen you haue a metls hauing Toom temperatue c^ Tecrystalli zation temperature > hene ver forming of- etal takes place it would alwas be a bot Such m iorking pro room +emperature <oceiS. Theq con not be cold oorced at

cracks are pesent on tne surface m propogaing in very Tap manner in atigue loading very vapd manner in Fatigue loaain thus the failure maq occur rapidlg hence the fatigue srerg th depends upon surface finish of specimen. Prob .S original do: 25 mm Longitud nal rue strain CET) given b where E Longituduna engg Strain Here volume of material emoiN conuta ·生 - 1275.5 프de2

Noca Er- en (1275.51) ET 1274. 51 Prob є VWe know thaf The lcad token by cable oil be carried by too diffrent materiuJ We knod hat necking occurs at ultimate srength point 6 at thi s point of ultimate strength E .5 P31819 8 lbs
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