MODELLING OF FRACTURE
I INTRODUCTION
1 lesson
1.Overview and aims of the course.
Basic mechanics parameters.
Computational fracture mechanics ( refrence Chapter 11 book T.L.Anderson). Software and possibilities.
Brief presentations of recent research projects: Norwegian-Japanese, ACCRIS, KOFAB, PRESS, DEFOBAL, SIP, DEEPIPE, EXPIPE
II BRITTLE FRACTURE
5 lessons
2.Mechanisms.Metallographic examinations.
*Cleavage micromechanisms of crack exstension in steels.
D.A. Curry. The Metal Society 1980.
Recent advances in the micro-modelling of cleavage fracture in steel.
John F. KnottSchool of Metallurgy and Materials. Univeristy of Birmingham. 1998.
*Prediction of brittle fracture in steel based on local fracture criteria.
A literature overview. Erling Østby .1998.
Introduction to metallographic methods and visit to SEM lab. Exercise with own specimens.
3.Constraint. T and Q
Development of the T and Q theories.
*Influence of non-singular stress terms and specimen geometry on small-scale yielding at crack tips in elastic-plastic materials. S.G. Larsson and A.J. Carlsson. Dept. of Strength og Materials and Solid Mechanics, The Royal Institute of Technology, Stockholm, Sweden 1972.
*Two-parameter Characterization of elastic-plastic crack-tip fields.
C. Betegón and J.W. Hancock. Transactions of ASME 1991.
*Family of crack-tip fields characterized by a triaxiality parameter - I. Structure of fields. N.P. O'Dowd and C.F. Shih. Journal of the mechanics and physics of solids. 1991.
*Family of crack-tip fields characterized by a triaxiality parameter - II. Fracture
applications. N.P. O'Dowd and C.F. Shih. Journal of the mechanics and physics of solids. 1991
4.Local approach, Weibull statistics.
Coupling between continuum mechanics and physical mechanisms.
* A local criterion for cleavage fracture of a nuclear pressure vessel steel.
F.M. Bermin. Metallurgical Transactions A, vol.14A. 1983.
*Procedure to measure and calculate material parameters for the local approach to
fracture using notched tensile specimens.
ESIS Pg-94. 1998.
5.Mismatch.
Historical development. The JQM Approach
* Parameter Characterisation of the Near Tip Stress Fields for a Bi-Material Elastic-Plastic Interface Crack. Zhang, Z.L., Hauge, M. and Thaulow, C. Int. Journal of Fracture, 79:65-83, 1996.
*.J-Q-M approach for failure assessment of fusion line cracks: two material and three material models. Thaulow, C., Zhang, Z.L., Ranestad, Ø. and Hauge,M. ASTM STP 1360, Fatigue and Fracture Mechanics: 30th Volume. St.Louis. June 1998
* Constraint effects on crack tip stress fields for cracks located at the fusion line of weldments. Thaulow, C.,Zhang, Z.L., Hauge,M. Burget,W. and Memhard,D. Computational Material Science, Vol 15, pp.275-284, 1999.
CaseBrittle: JQM calculations
a)Presentation of case, parameters, aim with calculations, illustrative example with all steps described
b)Calculation procedures. Presentation of results
III DUCTILE FRACTURE
5 lessons
7.Mechanisms. Metallographic examinations.
Experience from Strategic Institute Research Program. Visit to SEM lab.
*Skadeutvikling i aluminiumslegeringer-observasjoner og modellering. Jack Ødegård, Ketill Pedersen og Hans Jørgen Roven.SINTEF Materials Technology. 1998
8. Cell model simulation of void growth and coalesence.
*Void growth and coalescence in porous plastic solids. J.Koplik and A.Needleman. Solids Structures, Vol 24, No 8, pp. 835-853. 1988
9. Analyttical void growth models
*On the ductile enlargement of voids in triaxial stress fields. J.R.Rice and D.M.Tracy. J.Mech.Phys.Solids, Vol 17, pp.201-217. 1969.
10.Ductile Fracture by the Complete Gurson Model
*Zhang, Z. L., Thaulow C., and Ødegård, J.:“A complete Gurson model based approach for ductile fracture”,Paper presented at HSI/TWI Structural Integrity Seminar, October 1998. To be published in Engineering Fracture Mechanics
CaseDuctile: Complete Gurson calculation for tensile tests.
c)Presentation of case, parameters, aim with calculations, illustrative example with all steps described
d)Calculation procedures. Presentation of results
IV BRITTLE/DUCTILE
11.Mechanisms. Challenges.
*Einsatz mikromechanischer Schadigungsmodelle im sprød-duktilen Uebergangsbereich. Dr.ing Thesis Gunter Bernauer, 1997.
*The role of geometry and crack growth on constraint and implications for ductile/brittle fracture. N.P. O`Dowd, C. F.Shih and R.H.DoddsASTM STP 1244, 1995.
*Modelling of crack growth resistance using computational cells with microstructurally-based length scales. C.F.Shih and L.Xia. ASTM STP 1244. 1995
*Numerical Modelling of Crack Growth in Ductile-Brittle Transition Regime. X.Gao. Ph.D. Thesis 1998
*Damage mechanics models of ductile crack growth in welded specimens. M.C.Burstow and I.C.Howard. 2000.
*Papers on the Cohezive zone approach.
CaseTransition: Calculation of brittle and ductile fracture in the same MBL model