Lagoda Lifetime Estimation of Welded Joints

1. Auflage 2008
ISBN: 978-3-540-77062-6
Verlag: Springer-Verlag
Format: PDF
Kopierschutz: Adobe DRM (»Systemvoraussetzungen)

E-Book, Englisch, 118 Seiten

In the paper the author attempts to assess the fatigue life of chosen welded joints. It focuses especially on chosen problems that accompany deter- nation of the fatigue life of welded joints, taking into consideration the strain energy density parameter. Chapter 2 describes the welded joint as a stress concentrator. The state of stress and strain in the notch are described and theoretical and fatigue coefficients are indicated. The fatigue coef- cient of the notch effect is estimated on the basis of fictitious radius in the notch root. Chapter 3 presents a model of fatigue life assessment under uniaxial stress state with statistical handling of data presented. The new energy model of fatigue life assessment, which rests upon the analysis of stress and strain in the critical plane, is described in detail in chapter 4. The principle of such a description is presented in the uniaxial as well as in - axial state of loading. Chapter 5 contains the analysis of tests of four ma- rials subjected to different loadings: cyclic, variable-amplitude with Ga- sian distribution, and variable amplitude with Gaussian distribution and overloading for symmetric and pulsating loading. The analysis is based on the determined fatigue characteristics for all the considered materials. Chapter 6 shows the application of the model in the fatigue life assessment in the complex state of loading (bending with torsion of flange-tube and tube-tube joints) based on fatigue research of steel and aluminum welded joints carried out in well-known German centres.

Autoren/Hrsg.

Lagoda, Tadeusz

Inhaltsverzeichnis

1;Preface;5
2;Contents;7
3;Notation;9
4;1 Introduction;11
5;2 Welded Joints as the Stress Concentrator;15
5.1;2.1 The Complex Stress State in the Notch;15
5.2;2.2 Theoretical Notch Coefficient;18
5.3;2.3 The Fatigue Notch Coefficient;20
5.4;2.4 The Fictitious Radius of the Welding Notch;22
5.5;2.5 The Notch Coefficient with the Use of the Fictitious Notch Radius;25
6;3 The Stress Model for the Assessment of Fatigue Life Under Uniaxial Loading;26
6.1;3.1 Algorithm for the Assessment of Fatigue Life Under Uniaxial Loading State;26
6.2;3.2 Statistic Evaluation;36
7;4 The Energy Model of Fatigue Life Assessment;41
7.1;4.1 The Energy Parameter Under Uniaxial Loading;41
7.2;4.2 The Energy Parameter Under Multiaxial Loading;47
7.2.1;4.2.1 The Generalized Criterion of the Parameter of Normal and Shear Strain Energy Density Parameter in the Critical Plane;48
7.2.2;4.2.2 The Criterion of Maximum Parameter of Shear and Normal Strain Energy Density on the Critical Plane Determined by the Normal Strain Energy Density Parameter;50
7.2.3;4.2.3 The Criterion of Maximum Parameter of Shear and Normal Strain Energy Density in the Critical Plane Determined by the Shear Strain Energy Density Parameter;51
7.3;4.3 Algorithm for Fatigue Life Assessment;55
8;5 An Example of Fatigue Life Evaluation Under Simple Loading;67
8.1;5.1 Fatigue Tests;67
8.1.1;5.1.1 Tests Under Constant-amplitude Loading;70
8.1.2;5.1.2 Tests Under Variable-amplitude Loading;74
8.2;5.2 Verification of the Results Obtained Under Variable-amplitude Loading;75
9;6 An Example of Fatigue Life Evaluation Under Complex Loading States;78
9.1;6.1 Fatigue Tests;78
9.2;6.2 Verification of the Criteria Under Constant-amplitude Loading;87
9.2.1;6.2.1 The Parameter of Shear and Normal Strain Energy Density on the Critical Plane Determined by the Parameter of Normal Strain Energy Density;87
9.2.2;6.2.2 The Parameter of Shear and Normal Strain Energy Density in the Critical Plane Determined by the Shear Strain Energy Density Parameter;93
9.2.3;6.2.3 The Influence of Different Frequencies of Bending and Torsion on Fatigue Life;98
9.3;6.3 Verification Under Variable-amplitude Loading;99
10;7 Conclusions;102
11;References;104
12;Summary;123