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Technical Paper

Cutting Force Model Incorporating Plastic Flow Characteristics of Workpiece Material and FEM verification

1997-04-07
971582
The plasticity characteristics of the material were used to model the cutting force material, and were verified by using FEM techniques. In addition, the solutions generated by The Merchant's Circle were proven by vector algebra, and a shear angle solution which uses the plasticity characteristics of the material is also presented. A good agreement was found between the mathematical models, FEM results, and experimental data results found in open literature.
Technical Paper

Effect of System Stiffness on Friction and Wear

1994-04-01
941110
A systematic study has been carried out to investigate the effect of change in the stiffness of the system incorporating a tribo contact, on the operational characteristics of a friction pair. Using a pin on disk apparatus six different system stiffnesses were introduced. With each system stiffness a steel sample is slide against two counter bodies: a smooth metal surface, and an abrasive surface. Friction force, normal force, and wear rate are measured. Results indicate that system stiffness has significant effect on wear, vibration, and contact forces. An increase in system stiffness is found to increase wear rate. As the wear rate increased, the coefficient of friction was also found to increase. Mathematical models have been developed to predict wear under varying system stiffness. These results are of particular importance in miniature devices involving moving parts.
Technical Paper

Wear of Bearing Materials

1994-04-01
941111
Wear characteristics of four bearing materials have been investigated under different sliding conditions. The bearing materials used were CDA 954, CDA 863, CDA 932, and CDA 938. Using a Taber Wear Tester, a cylinder on a flat geometry was used as a tribo contact pair. All bearing materials in the form of a thick cylindrical disk were subjected to combined sliding-rolling motion against a rotating flat disk. The flat disk was either an abrasive disk, or a very soft steel disk, or a hardened steel disk with and without lubrication. Wear was measured as weight loss after several thousand cycles of rotation. Maximum wear of the bearing materials occurred when the counter body was a very soft steel disk. These results together with the wear rate of each bearing material sliding against four different counter bodies are presented. These results are found to be of practical importance in the design and application of journal bearings made of materials used in this investigation.
Technical Paper

Thermal Stress Analysis of a Novel Design Air-Gap Insulated Piston

1994-04-01
941069
A novel design of an air-gap insulated piston has been proposed which is expected to give a longer life compared to the existing designs. The new composite piston is made of a crown piece which is fitted to the base of a piston through a gasket by an interference fitting and locked by oval shaped rivets radially. A steady state two dimensional thermal analysis is performed on the piston to predict the temperature distribution, then a thermo-elastic analysis is performed to obtain thermal stress distribution. Further, a pure mechanical stress analysis is performed on the piston. These analyses are performed on a Aluminum single piece piston, as reference and an air-gap insulated Ultra High Strength Steel piston using finite element method. Constant temperatures are assumed at gas, liner and oil boundaries of the piston. Also, film coefficients on the piston boundaries are kept constant.
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