Reliability testing thermal-cycle analysis

Since all engine-tested valves failed due to volume flaws, the valve s transient reliability was based on volume analysis. Figure 6 shows the pressure variation as a function of time during a typical combustion cycle of 0.0315 seconds. The pressure is applied to the valve s face and other exposed surfaces within the cylinder. The maximum attained pressure during the combustion cycle was estimated to be 15.85 MPa (Corum et al. ). A 445 N (100 lb) force due to spring preload is applied to the valve stem when it is in the open position. At the moment the valve closes an impact force of 1335 N (300 lb) is applied to the valve stem. In addition, thermal stresses due to the temperature distribution in the valve are superposed to the mechanical stresses. 

---