High Cycle Fatigue Life of 70 Series Engine Cast Aluminum Rotor Housing. Final Report on Task 2.1.6 'Extended Life Studies'

摘要

Fatigue studies conducted to project the expected life and safety factors of the rotor housing of cast aluminum 2013R natural gas fueled rotary engines (NGREs) are documented. The rotor housing was selected because previous studies showed this major engine component to be the critical item in determining fatigue life. The report describes the sequential steps required for fatigue life calculations, including the heat transfer, thermal stress, pressure stress, fatigue life, and safety factor analyses. The fatigue analysis requires the determination of thermal and presure stresses. The former is viewed as providing the steady-state component, while the latter contributes both to the steady-state and the alternating components of the stresses in the fatigue analysis. Both of these stresses are a function of the engine peak combustion pressure at the rated condition, but are somewhat independent of speed. The rated speed enters only in the calculation of heat transfer coefficients, and when translating the projected cycles-to-failure into hours of operating life.