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Journal Article

Effects of Non-Associated Flow on Residual Stress Distributions in Crankshaft Sections Modeled as Pressure-Sensitive Materials under Fillet Rolling

2015-04-14
2015-01-0602
In this paper, the evolution equation for the active yield surface during the unloading/reloading process based on the pressure-sensitive Drucker-Prager yield function and a recently developed anisotropic hardening rule with a non-associated flow rule is first presented. A user material subroutine based on the anisotropic hardening rule and the constitutive relation was written and implemented into the commercial finite element program ABAQUS. A two-dimensional plane strain finite element analysis of a crankshaft section under fillet rolling was conducted. After the release of the roller, the magnitude of the compressive residual hoop stress for the material with consideration of pressure sensitivity typically for cast irons is smaller than that without consideration of pressure sensitivity. In addition, the magnitude of the compressive residual hoop stress for the pressure-sensitive material with the non-associated flow rule is smaller than that with the associated flow rule.
Technical Paper

Friction Reduction Trends in Modern Engines

2004-03-08
2004-01-1456
A number of spark ignition engines from 1997 to 2003 are analyzed for their overall friction characteristics using the Willans line approach. This methodology appears to be quite robust across many different types of engines. Using a variety of partial and complete engine maps from multiple manufacturers, it is confirmed that engine friction has been decreasing over the decades (compared to past studies). Overall there has been a 25% reduction over 30 years. It is also demonstrated that thermal efficiency (defined here as the slope of fuel mep and bmep excluding enrichment) has been remaining steady during the same period. The application to aggregate engine models is discussed.
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