Richard M. Christensen
Brief Biography

Stress Based Failure Criteria for
Materials Science and Engineering

Overview

Three dimensional failure criteria are given for various materials classes.  These include both isotropic and anisotropic material symmetries, and are applicable for macroscopic homogeneity.  In the isotropic materials form, the properly calibrated failure criteria can distinguish ductile from brittle failure for specific stress states.  Although most of the results are relevant to quasi-static failure, some are for time dependent failure conditions as well as for fatigue conditions.

Contents

1. Purpose and Conditions - Attention is given to many failure related matters, but especially to the physical and mathematical basis for the failure criteria under examination.
   
    
2. Yield and Failure Criteria for Isotropic Materials - Historical and modern failure criteria for isotropic materials are outlined and discussed.  A recently developed yield and failure formalism is given which is completely calibrated by the two failure properties in uniaxial tension and compression. It necessarily involves an inherent transition from ductile to brittle failure mechanisms across the range of materials types.
   Manuscripts of Published Papers
   
    
3. Failure Criteria for Anisotropic Fiber Composite Materials - A physically based failure formulation is given for aligned fiber composite materials.  Two coordinated failure criteria are derived, one for the fiber controlled mode and one for the matrix controlled mode.  The targeted applications are to carbon fiber, polymeric matrix (or equivalent) types of systems.
   
    
4. Cumulative Damage Leading to Fatigue and Creep Failure for General Materials - Four different cumulative damage models are compared. All four models are calibrated by constant amplitude failure data bases and do not contain any adjustable parameters. Only the flaw growth theory/model shows a consistent and realistic life prediction capability for variable amplitude conditions.
   Manuscript of Published Paper
   
    
5. Progressive Damage Leading to Failure for Fiber Composite Laminates
   (coming later)
   
    
6. Critical Tests for Failure Criteria
   (coming later)

Failure Surface Graphics

Failure Characterization

The First Failure Criterion

Is It Stress or Strain

A Basic Failure Mechanism

Can Atomic/Nano Scale
Failure Events Predict
Macroscopic Failure

The Ductile-Brittle Problem

Applications

Damage

Acknowledgment

Copyright© 2009
Richard M. Christensen

Looking Ahead