New Delhi: Tejas-LSP4 completed the first one hour flight of indigenous aircraft bearings for the critical gearbox and all performance  met the stringent parameters. Gearbox is developed from scratch by CVRDE, reports Twitter handle Alpha Defence.

CVRDE is in the process of developing indigenous bearing materials for use in Light Combat Aircraft (LCA) applications.  In this connection, static and fatigue studies were carried out on the material, to qualify the material for its use in Tejas.

Tension, sharp-notch tension and uniaxial compression tests were carried out on the material at room, elevated (up to +300° C) and sub-zero (-75° C) temperatures.  Plane-strain fracture toughness tests were carried as per ASTM E 399 – 09 employing compact tension  specimens. Low cycle fatigue tests were carried out under four values of strain ranges, viz., 0.3%, 0.4%, 0.5% and 0.6%.

The tests were carried out under strain-control and the specimens were subjected to constant amplitude triangular cyclic loading. High cycle fatigue tests were carried out under four values of stress ranges, viz., 900 MPa, 1300 MPa, 1900 MPa and 2500 MPa.  The tests were carried out under load-control and the specimens were subjected to constant amplitude sinusoidal cyclic loading. Corrosion fatigue tests were also carried out employing eccentrically-loaded single edge notch tension  specimens.