Thermomechanical Fatigue Behavior of a Silicone Carbide Fiber-Reinforced Calcium Aluminosilicate Glass-Ceramic Matrix Composite
Abstract
Ceramic matrix composites are being considered for use in advanced turbine engines and other applications where thermomechanical fatigue (TMF) conditions exist. Isothermal fatigue and in-phase TMF tests were performed on a unidirectional, continuous-fiber, Nicalon reinforced calcium aluminosilicate glass-ceramic material (O16, SiC/CAS-II). Monotonic tensile tests were performed at 1100 deg C (2012 deg F) and 100 MPa/sec to determine the material's ultimate strength and proportional limit . Isothermal fatigue tests at 1100 deg C (2012 deg F) employed two loading profiles, a triangular waveform with ramp times of 60 seconds, and a similar profile with a superimposed 60 second hold time at These tests used a maximum stress of 100 MPa (40% of sigma pl) R = 0.1. TMF loading profiles were identical to the isothermal loading profiles. During the TMF tests, the temperature was cycled between 500 and 1100 deg c(932 and 2012 deg F) in time with the load. Run out was arbitrarily set at 1000 cycles for all fatigue profiles. All fatigued specimens reached run out and were tested in tension at 1100 deg C and 100 MPa/sec immediately following the isothermal and thermomechanical tests. Residual modulus, residual strength, hysteretic modulus, and strain accumulation were all explored as possible damage indicators. Strain accumulation appeared to be the parameter which allowed for the greatest distinction to be made among the types of tests performed. Stress analyses performed on the fiber and matrix material and creep data for the composite suggest that matrix creep is the primary source of damage in the isothermal and thermomechanical fatigue profiles investigated for this project.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 1991
- Accession Number
- ADA249870
Entities
People
- Lawrence M. Butkus
Organizations
- Air Force Institute of Technology