Accession Number : ADA299687

Title :   Fatigue Crack Growth Behavior of a Titanium Matrix Composite Under Thermomechanical Loading.

Descriptive Note : Doctoral thesis,

Corporate Author : WRIGHT LAB WRIGHT-PATTERSON AFB OH

Personal Author(s) : Blatt, Paul A.

PDF Url : ADA299687

Report Date : DEC 1993

Pagination or Media Count : 240

Abstract : The crack growth characteristics of a 4-ply, unidirectional, titanium matrix composite, SCS-6/ti-6Al-2Sn4Zr-2Mo, subjected to thermomechanical fatigue were investigated. A linear summation model was developed to predict the isothermal and thermomechanical fatigue (TMF) crack growth rates of the composite. The linear summation approach assumes the total fatigue crack growth rate is a combination of a cycle-dependent and a time-dependent component. To assist the modeling effort, a series of isothermal, in-phase, and out-of-phase crack growth test were conducted. The test temperatures ranged from 15000 to 53800 and the fastest thermal frequency was 0.0083 Hz. With the excepton of the 15000 isothermal test, the model was able to correlate all the baseline fangue crack growth test data between oK of 50 to 9OMPa. In additon, the model was able to predict the fatigue crack growth rate of a proof test which involved a continual change in temperature range and load range to produce a constant crack growth rate. The proof test began under isothermal conditions at the maximum temperature and ended under in-phase TMF conditions.

Descriptors :   *METAL MATRIX COMPOSITES, *CRACK PROPAGATION, *FATIGUE(MECHANICS), *THERMAL FATIGUE, *AEROSPACEPLANES, *TITANIUM ALLOYS, THERMOMECHANICS, AIR BREATHING ENGINES, NONDESTRUCTIVE TESTING, HIGH TEMPERATURE, FINITE ELEMENT ANALYSIS, DAMAGE ASSESSMENT, FIBER REINFORCED COMPOSITES, THESES, FABRICATION, MOLYBDENUM, TOUGHNESS, MATRIX MATERIALS, CHEMICAL COMPOSITION, IMPACT STRENGTH, COMBUSTION, GAS TURBINES, ALUMINUM, THERMAL EXPANSION, LIGHTWEIGHT, ZIRCONIUM, DUCTILITY, TOLERANCES(MECHANICS), AEROSPACE INDUSTRY, SILICON CARBIDES, THERMAL STRESSES, HYPERSONIC VEHICLES, ISOTHERMS, CREEP STRENGTH.

Subject Categories : Laminates and Composite Materials
      Properties of Metals and Alloys
      Thermodynamics
      Research and Experimental Aircraft

Distribution Statement : APPROVED FOR PUBLIC RELEASE