文档介绍：Institut of Materials Engineering
PHD Programme
Fatigue life calculation of welded joints based on fracture
mechanics
Ahmed M. Al-Mukhtar*
MSc. Materials and Manufacturing Engineering
BSc. Aeronatical Engineering
Supervisors: Prof. Dr.- Ing. habil. H. Biermann*
Prof. Dr.- Ing. P. Hübner**
*Institute of Materials Engineering, Technische Universität Bergakademie Freiberg, Germany
**Fachhochschule Mittweida, Mittweida, Germany
Outlines
1) Aim of reaserch (Objectives) - Procedure
2) Introduction (Why fracture mechanics?)
3) Finite Element Analysis (FEA)
- Modelling
- Crack path direction
4) Standard and fatigue design mendations
5) Results (benchmarking)
- SIF calculation parison for some welded joints
- Fatigue life calculation parison for some welded joints
- Case study not presented in the mendation
6) Conclusions
2
. Aim Ziel and – Proecdures und Aufgabenstellung
Aim
- Accurate SIF calculation
- Moreover, calculate the fatigue life, and the fatigue strength (FAT) of the welded
joints with different geometries that not presented in mendations
Procedures
1) FE modeling which give accurate stress intensity factor.
2) With knowledge of the stress intensity factors KI at different crack depths (a), it
was possible to make curve fits for KI( a) for the different loading and use Paris’
law to integrate numerically and calculate the expected fatigue life for the
specimens.
3) Case studies can be consulted, and the need for well thought out benchmarking
of analytical results against experimental databases-IIW
3
. Introdcution Ziel – und - Why Aufgabenstellung Fracure Mechanics?
- One of the most important deterioration mechanisms of Aloha
Aircrafts, ships and steel bridge structures which occur in
service condition is Fatigue .
- Fatigue Failure , accounts for at least 75% of all machines
and structures failures
- Crack normally existed! But may be accelerated due to
enviro