Paris' law

About: Paris' law is a research topic. Over the lifetime, 13815 publications have been published within this topic receiving 224818 citations. The topic is also known as: Paris-Erdogan law.

Mechanical Behavior of Materials: Engineering Methods for Deformation, Fracture, and Fatigue

Abstract: (NOTE: Each chapter concludes with a Summary, New Terms and Symbols, References, and a Problems and Questions section.) 1. Introduction. 2. Structure and Deformation in Materials. 3. A Survey of Engineering Materials. 4. Mechanical Testing: Tension Test and Other Basic Tests. 5. Stress-Strain Relationships and Behavior. 6. Review of Complex and Principal States of Stress and Strain. 7. Yielding and Fracture under Combined Stresses. 8. Fracture of Cracked Members. 9. Fatigue of Materials: Introduction and Stress-Based Approach. 10. Stress-Based Approach to Fatigue: Notched Members. 11. Fatigue Crack Growth. 12. Plastic Deformation Behavior and Models for Materials. 13. Stress-Strain Analysis of Plastically Deforming Members. 14. Strain-Based Approach to Fatigue. 15. Time-Dependent Behavior: Creep and Damping. Appendix A: Review of Selected Topics from Mechanics of Materials. Appendix B: Statistical Variation in Materials Properties. Bibliography. Index.

Fracture mechanics for piezoelectric ceramics

Abstract: We Study cracks either in piezoelectrics, or on interfaces between piezoelectrics and other materials such as metal electrodes or polymer matrices. The projected applications include ferroelectric actuators operating statically or cyclically, over the major portion of the samples, in the linear regime of the constitutive curve, but the elevated field around defects causes the materials to undergo hysteresis locally. The fracture mechanics viewpoint is adopted—that is, except for a region localized at the crack tip, the materials are taken to be linearly piezoelectric. The problem thus breaks into two subproblems: (i) determining the macroscopic field regarding the crack tip as a physically structureless point, and (ii) considering the hysteresis and other irreversible processes near the crack tip at a relevant microscopic level. The first Subproblem, which prompts a phenomenological fracture theory, receives a thorough investigation in this paper. Griffith's energy accounting is extended to include energy change due to both deformation and polarization. Four modes of square root singularities are identified at the tip of a crack in a homogeneous piezoelectric. A new type of singularity is discovered around interface crack tips. Specifically, the singularities in general form two pairs: r1/2±ieand r1/2±ie, where e. and k are real numbers depending on the constitutive constants. Also solved is a class of boundary value problems involving many cracks on the interface between half-spaces. Fracture mechanics are established for ferroelectric ceramics under smallscale hysteresis conditions, which facilitates the experimental study of fracture resistance and fatigue crack growth under combined mechanical and electrical loading. Both poled and unpoled fcrroelectrie ceramics are discussed.

A crack opening stress equation for fatigue crack growth

Abstract: A general crack opening stress equation is presented which may be used to correlate crack growth rate data for various materials and thicknesses, under constant amplitude loading, once the proper constraint factor has been determined. The constraint factor, alpha, is a constraint on tensile yielding; the material yields when the stress is equal to the product of alpha and sigma. Delta-K (LEFM) is plotted against rate for 2024-T3 aluminum alloy specimens 2.3 mm thick at various stress ratios. Delta-K sub eff was plotted against rate for the same data with alpha = 1.8; the rates correlate well within a factor of two.