AEROSPACE MATERIAL DAMAGE CHARACTERIZATION AND LIFE PREDICTIONS

RABEEH, B. M.; SOBOYEJO, W. 0.; ROKHLIN, S. I.

doi:10.21608/asat.1997.25404

AEROSPACE MATERIAL DAMAGE CHARACTERIZATION AND LIFE PREDICTIONS

Document Type : Original Article

Authors

¹ Department of Automotive Engineering, Military Technical College, Cairo, Egypt.

² Department of Materials Science and Engineering, The Ohio State University, Columbus, Ohio, USA.

³ Department of Industrial Welding and System Engineering, The Ohio State University, Columbus, Ohio, USA.

10.21608/asat.1997.25404

Abstract

There is currently a concerted global effort to produce hypersonic vehicles. Structural materials in such vehicles must able to withstand high temperatures and retain a high stiffness, while carrying significant stresses. Titanium 15-3 metal matrix composites reinforced with SIC (SCS-6) fibers are being investigated to see if they satisfy the requirements for applications in such hypersonic vehicles. However, there is a limited understanding of structural failure modes in such composites. Fatigue damage mechanisms were identified in metal matrix composites via destructive and non-destructive testing (acoustic emission technique). Based on experimental evidence a micromechanical modeling approache was developped for the prediction of fatigue life in such composite materials. The model involves the use of crack-tip shielding concepts, in the assessments of crack bridging phenomena during fatigue crack growth. In addition, an acoustic emission modeling was developped utilizing micromechanical modeling and fracture mechanics concepts. Fatigue life predictions were obtained and compared with the actual/measured fatigue lives. The current approach of non-destructive characterization to damage history and life prediction will lead to a new maintenance philosophy under realistic service conditions. Characterization as well as the location of fatigue damage under real service conditions will allow the airframe to utilize condition-based maintenance instead of programmed-depot maintenance.