Accession Number:

ADA254385

Title:

Theoretical and Experimental Studies on the Foundation of Mesomechanics

Descriptive Note:

Final rept. Nov 1989-Apr 1992

Corporate Author:

ILLINOIS UNIV AT CHICAGO CIRCLE DEPT OF CIVIL ENGINEERING MECHANICS AND METALLURGY

Report Date:

1992-06-28

Pagination or Media Count:

130.0

Abstract:

The report summaries a closely coupled experimental and theoretical investigations of various stages of Fracture Process 1 accumulation of damage on submicroscopical and microscopical scales leading to crack initiation 2 slow subcritical crack growth and an evolution of the damage zone 3 transition to dynamic crack growth and the catastrophic failure. The experimental part of the program is focused on the observation and quantitative characterization of damage preceding and accompanying crack initiation and growth. A special experimental setup for studying the fracture process under variable stress field is reported in Chapter 2. A leading role of crack-damage interaction in fracture process is well documented. A new formalism for solution of crack-microcrack array interaction problem and its successful implementation in the evaluation of crack layer driving forces is presented in Chapter 3. A new model of the process zone, which generalizes the well-known Dagdale-Barenblatt model is presented in Chapter 4. A new measure for material toughness and the prediction of R-curve behavior illustrate the practical application of our model. Experimental examinations of our model under various test conditions are reported in Chapters 4, 5 and 6. The development of the constitutive equations for Crack Layer evolution and their experimental examinations under stress relaxation, fatigue and creep conditions are reported in Chapters 5 and 6. An accelerated test procedure and the formulation of crack layer instability criteria as a substitution for the conventional fracture toughness parameters are also discussed in Chapter 6.

Subject Categories:

  • Plastics
  • Mechanics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE