MSE 230 Assignment 5 Fall 2013 due 9 19 9 20 Problems with a by them will not be graded but solutions will be provided Specifically problems 1 2 5 and 9 will be graded 1 Callister Problem 6 20 A brass alloy is known to have a yield strength of 275 MPa a tensile strength of 380 MPa and an elastic modulus of 103 GPa A cylindrical specimen of this alloy 12 7 mm in diameter and 250 mm long is stressed in tension and found to elongate 7 6 mm On the basis of the information given is it possible to compute the magnitude of the load that is necessary to produce this change in length If so calculate the load If not explain why 2 A cylindrical rod 100 mm long and having a diameter of 10 0 mm is to be deformed using a tensile load of 27 500 N It must not experience either plastic deformation or a diameter reduction of more than 7 5 x 10 3 mm Of the materials listed as follows which are possible candidates Justify your choice s Material Aluminum Alloy Brass Alloy Steel Alloy Titanium Alloy Modulus of Elasticity GPa 70 101 207 107 Yield Strength MPa 200 300 400 650 Poisson s Ratio 0 33 0 35 0 27 0 36 3 A specimen of ductile cast iron having a rectangular cross section of dimensions 4 8 mm x 15 9 mm is deformed in tension Using the load elongation data tabulated below complete problems a through c a Plot the data as engineering stress versus engineering strain b Compute the modulus of elasticity c Determine the yield strength at a strain offset of 0 002 Load N 0 4740 9140 12920 16540 18300 20170 22900 25070 Length mm 75 000 75 025 75 050 75 075 75 113 75 150 75 225 75 375 75 525 1 26800 28640 30240 31100 31280 30820 29180 27190 24140 18970 75 750 76 500 78 000 79 500 81 000 82 500 84 000 85 500 87 000 88 725 4 A cylindrical specimen of a brass alloy 7 5 mm in diameter and 90 0 mm long is pulled in tension with a force of 6000 N The force is subsequently released a Compute the final length of the specimen at this time The tensile stress strain behavior for this alloy is shown in Fig 6 12 b Compute the final specimen length when the load is increased to 16 500 N and then released 5 A copper rod is deformed using a uniaxial tensile force of 15 000 N Deformation continues until sufficient strain hardening has occurred such that the applied force is too small to allow further deformation After deformation the rod has a diameter of 0 01 m and a length of 1 5 m Assume that copper follows the strain hardening law T K nT with K 315 MPa and n 0 54 Calculate the initial length of the rod before deformation began 6 Callister Problem 6 51 a A 10 mm diameter Brinell hardness indenter produced an indentation 2 50 mm in diameter in a steel alloy when a load of 1000 kg was used Compute the HB of this material b What will the diameter of an indentation to yield a hardness of 300 HB when a 500 kg load is used 7 Similar to Callister Problem 15 19 For each of the following pairs of polymers do the following 1 state whether or not it is possible to decide whether one polymer has a higher tensile modulus than the other 2 if this is possible note which has the higher tensile modulus and then cite the reason s for your choice and 3 if it is not possible to decide then state why a Branched and atactic poly vinylchloride with a weight average molecular weight of 100 000 g mol linear and isotactic poly vinylchloride having a weight average molecular weight of 75 000 g mol b Branched polyethylene with a number average molecular weight of 100 000 g mol atactic polypropylene with a number average molecular weight of 150 000 g mol c Branched polyethylene with a weight average molecular weight of 100 000 g mol linear polyethylene with a weight average molecular weight of 100 000 g mol d Atactic polystyrene with a weight average molecular weight of 50 000 g mol atactic polypropylene with a number average molecular weight of 150 000 g mol 2 8 A tensile test is performed on a 1 0 mm diameter polyethylene fiber During the test a long necked region develops similar to the test specimen show in Fig 15 14 of Callister The necked region resembling a strip of dental floss is cut from the rest of the test specimen and subsequently remounted in the mechanical testing machine Will the Young s modulus of this new test specimen be higher lower or the same as the original fiber Please explain your answer 9 The slip system for the FCC crystal structure is 111 110 a In a cube sketch the 1 11 plane b Determine and write down the specific 110 that border the 1 11 Indicate these directions in your 1 11 using arrows These directions are called slip directions c If a tensile stress is applied in the 001 and 001 in which slip direction s is slip least likely to occur based on your drawing from parts a and b Please explain briefly 10 A tensile stress is applied along the 001 in an aluminum single crystal a If slip initiates on the slip system 111 01 1 at a tensile stress of 7 8 MPa calculate the critical resolved shear stress b Briefly explain the difference between the applied stress the yield stress the shear stress and the critical resolved shear stress 3
View Full Document
Unlocking...