1. an undulated surface that is designed to reduce friction byeliminating wear particles from the sliding interface. Theinterface is subjected to normal force N. The sliding speed is solow that the interfacial temperature rise is negligible relative tothe melting point of the material. We are planning to use metalsfor the sliders.
a. Determine the optimum dimensions of the undulatedtopography.
b. Discuss the consequence of deviating from the optimumgeometry.
2. A conical asperity is plowing the surface. Determine thecoefficient of friction.
3.At the beginning of sliding, there are 10,000 particles of 1micron in diameter between two flat Armco iron surfaces. Thehardness of Armco iron is 1000MPa. After one day of sliding, theparticles have agglomerated into 100 equal sized spheres. Whatwould be the change in friction coefficient? Plowing is primarilyresponsible for friction. State your assumptions clearly.At thebeginning of sliding, there are 10,000 particles of 1 micron indiameter between two flat Armco iron surfaces. The hardness ofArmco iron is 1000MPa. After one day of sliding, the particles haveagglomerated into 100 equal sized spheres. What would be the changein friction coefficient? Plowing is primarily responsible forfriction. State your assumptions clearly.
4. A composite bearing material has been developed usinguniaxial graphite fibers embedded in a polyurethane matrix. Thefibers are perpendicular to the sliding surface. Estimate thecoefficient of friction and wear rate of the composite when it issliding against a 52100 steel sphere of 0.02 m in diameter. Stateyour assumptions
5. You have developed a new copper alloy that has titaniumdiboride (TiB2) as second phase particles. The total volumefraction of TIB2 is 3 %. The particle size is uniform throughoutthe matrix of copper. You made five samples by varying particlesize as follows: 0.05 microns, 0.1 microns, 1 microns, 10 microns,and 100 microns.
(a) Estimate the hardness of each material.
(b) Estimate the wear coefficient of each sample, assuming thatthey wear by delamination.
State your assumptions clearly
