Fracture and Fatigue Emanating from Stress Concentrators

ISBN-13: 9789048164172 / Angielski / Miękka / 2010 / 233 str.

G. Pluvinage

Opis

A vast majority of failures emanate from stress concentrators such as geometrical discontinuities. The role of stress concentration was first highlighted by Inglis (1912) who gives a stress concentration factor for an elliptical defect, and later by Neuber (1936). With the progress in computing, it is now possible to compute the real stress distribution at a notch tip. This distribution is not simple, but looks like pseudo-singularity as in principle the power dependence with distance remains. This distribution is governed by the notch stress intensity factor which is the basis of Notch Fracture Mechanics. Notch Fracture Mechanics is associated with the volumetric method which postulates that fracture requires a physical volume. Since fatigue also needs a physical process volume, Notch Fracture Mechanics can easily be extended to fatigue emanating from a stress concentration.

Spis treści

Preface. * 1: Notch effects in fracture and fatigue. 1.1. Notch effects in fracture. 1.2. Notch effects in fatigue. 1.3. Conclusion. * 2: Stress distribution at notch tip. 2.1. Introduction. 2.2. Elastic stress distribution at notch tip. 2.3. Stress distribution at notch tip for perfectly plastic material. 2.4. Stress distribution for an elastic perfectly plastic material. 2.5. Elastoplastic stress distribution for a strain hardening material. 2.6. Conclusion. * 3: Stress concentration factor. 3.1. Definition of the stress concentration factor. 3.2. Elastoplastic stress and strain concentration factor. 3.3. Relationship between the elastic and elasto-plastic concentration stress and strain concentration factors and the elastic one. 3.4. Evolution of elastic and elasto-plastic stress (or strain) concentration factor with net stress. 3.5. Comparison of evolution with net stress. 3.6. Conclusion. * 4: Concept of notch stress intensity factor and stress criteria for fracture emanating from notches. 4.1. Introduction. 4.2. Concept of stress intensity factor. 4.3. Concept of notch stress intensity factor. 4.4. Global stress criterion for fracture emanating from notches. 4.5. Local stress criterion for fracture emanating from notches. 4.6. Notch sensitivity in mixed mode fracture. 4.7. Conclusion. * 5: Energy criteria for fracture emanating from notches. 5.1. Introduction. 5.2. Influence of notch radius on the J integral. 5.3. Influence of notch radius on the &zgr; coefficients. 5.4. Local energy criterion for fracture emanating from notches. 5.5. Conclusion. * 6: Strain criteria for fracture emanating from notches. 6.1. Introduction. 6.2. Critical strain criterion for fracture emanating from notch. 6.3. Strain distribution at the notch tip. 6.4. Notch plastic zone. 6.5. Conclusion. * 7: The use of notch specimens to evaluate the ductile to brittle transition temperature; the Charpy impact test. 7.1. History of the Charpy impact test. 7.2. Stress distribution at notch tip of a Charpy specimen. 7.3. Local stress fracture criterion for Charpy V notch specimens. 7.4. Influence of notch geometry on brittle-ductile transition in Charpy tests. 7.5. Instrumented Charpy impact test. 7.6. Equivalence fracture toughness KIc and impact resistance KCV. 7.7. Conclusion. * 8: Notch effects in fatigue. 8.1. Notch effects in fatigue and fatigue strength reduction factor. 8.2. Relation between fatigue strength reduction factor and stress concentration factor. 8.3. Volumetric approach. 8.4. Influence of loading mode. 8.5. Notch effects in low cycle fatigue. 8.6. Conclusion. * 9: Role of stress concentration on fatigue of welded joints. 9.1. Introduction. 9.2. Stress concentration factor in welding cords. 9.3. Fatigue strength reduction factor. 9.4. Standard methods for the design against fatigue of welded components. 9.5. Innovative methods for the design against fatigue of welded joints. 9.6.