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# HW7 - which has the strength of 3500 MPa and an elastic...

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ME363 HW7 Fall 2010 Name Due: 12/7/2010 1. The tensile strength of a part produced by powder metallurgy can be empirically related to porosity as follows: 0 nP UTS UTS e = where P is the volume fraction of pores in solid, UTS 0 is the tensile strength at zero porosity, and the exponent ranges between 4 and 7 (assume to be 4 in this case). A fully dense ceramic has the properties of UTS 0 =140 MPa, E 0 = 310 GPA and density of 4000 kg/m 3 . (a) After compaction, it reaches 75% of the density of the solid material. If the linear shrinkage is 4% during sintering, determine the density after sintering. (b) Determine the UTS and modulus of elasticity of this material after sintering. 2. A glass-epoxy-reinforced plastic with longitudinal fibers contains 40% glass E-type fiber,
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Unformatted text preview: which has the strength of 3500 MPa and an elastic modulus of 73 GPa. The strength of the epoxy material is 120 MPa and its elastic modulus is 100 GPa. (a) Calculate the elastic modulus of the composite and the fraction of the load supported by the fibers. (b) If Boron fibers (strength: 3500 MPa, and elastic modulus: 380 GPa) are used instead of glass fibers, what should be the Boron fiber percentage to maintain the same elastic modulus? 3. A solid cylindrical part is to be made such that its final length is 30 mm. It is known that linear shrinkages of this part are 8% and 7% during drying and firing. Calculate (a) initial length of the part and (2) the dried porosity, P d , if the porosity of the fired part, P f , is 9%...
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