Starter air valve stress analysis.

 

This valve is employed in aircraft engines of new generation and intends to avoid the failures experienced in the past and caused by high levels of amplification factor of dynamic excitation and material degradation due to high temperatures.

The analyses were performed for the valve body made of 17-4PH, the bolted joint, the actuator in aluminum alloy C355 and for the internal components (screws, springs, piston, throttle valve). The new project is based essentially on a modified joint of interface that avoids the excitation of the natural frequencies caused by the forcing functions of the engine. The applied loads and the acceleration spectra were that ones imposed by the builders of the propeller (Pratt & Whitney and General Electric). Different types of 3-D models were employed in various kinds of analyses.

The principal investigation has regarded the evaluation of the frequency response to a forcing excitation acting in three directions and in the range of frequency 0-10000 Hz.