Gear Tooth Surface Fatigue Testing With Full Size Test Specimens

The design of critical helicopter gear systems must be based on well documented data which defines the capability of the materials utilized. Such detailed data is not available in either the usual engineering texts or from other sources. It is, therefore, necessary to test each parameter (strength, durability, scoring, etc.) individually so that an effective data base can be built. This paper describes the Gear Research Test Facility at Boeing Vertol with emphasis on its application to gear tooth durability testing and data analysis. An overview of the general configuration of the test rigs and their control and instrumentation systems is provided. The design of the various test specimens used in the rigs, the testing method and the techniques used for failure definition and evaluation are described. Within this context, the philosophy which led to the specific type of testing normally conducted at this facility is also discussed.