The document discusses fracture mechanics and damage analysis. It provides examples of rail fractures that derailed trains, brittle fractures in Liberty ships during World War II due to welds and thermal stresses, and the use of finite element analysis to model crack growth and stress distributions around cracks. Predicting damage accumulation and failure modes is important for structural integrity assessments.

1. Mecánica de Daño
Maestría en Ingeniería
Énfasis en Mecánica

3. “Rail Fracture Derails Punjab Mail; 29 Injured.” The Hindu, n.d.
http://www.thehindu.com/todays­paper/tp­national/article3392017.ece.
Sept. 06/2012

4. Fracturas en rieles

5. Un caso en Canada
● On 30 December 1999, at approximately 1900 eastern standard time,
Canadian National (CN) train No. U-783-21-30 was travelling westward from
Saint-Romuald, Quebec, on the north track of the Saint-Hyacinthe
Subdivision. At Mile 50.84, near Mont-Saint-Hilaire, Quebec, cars from train
No. U-783-21-30 derailed, fouling the adjacent south track. CN train No.
M-306-31-30, which was travelling eastward on the south track at the time,
collided with the cars of train No. U-783-21-30 as they derailed. The two
crew members on train No. M-306-31-30 were fatally injured in the accident.
Approximately 350 families living within a two-kilometre radius of the
accident site had to be temporarily evacuated. Two locomotives and 61 cars
were damaged in the accident. Approximately 2.7 million litres of
hydrocarbons spilled and caught fire, damaging private property, public
property and the environment.
contenu, E. name of the content author / N. en anglais de l’auteur du. (2002, August 15). English title / Titre en anglais.
Retrieved September 6, 2012, from http://www.tsb.gc.ca/eng/rapports-reports/rail/1999/r99h0010/r99h0010.asp

6. Un caso en Canada
● On 30 December 1999, at approximately 1900 eastern standard time,
Canadian National (CN) train No. U-783-21-30 was travelling westward from
Saint-Romuald, Quebec, on the north track of the Saint-Hyacinthe
Subdivision. At Mile 50.84, near Mont-Saint-Hilaire, Quebec, cars from train
No. U-783-21-30 derailed, fouling the adjacent south track. CN train No.
M-306-31-30, which was travelling eastward on the south track at the time,
collided with the cars of train No. U-783-21-30 as they derailed. The two
crew members on train No. M-306-31-30 were fatally injured in the accident.
Approximately 350 families living within a two-kilometre radius of the
accident site had to be temporarily evacuated. Two locomotives and 61
cars were damaged in the accident. Approximately 2.7 million litres of
hydrocarbons spilled and caught fire, damaging private property, public
property and the environment.
contenu, E. name of the content author / N. en anglais de l’auteur du. (2002, August 15). English title / Titre en anglais.
Retrieved September 6, 2012, from http://www.tsb.gc.ca/eng/rapports-reports/rail/1999/r99h0010/r99h0010.asp

7. Mecánica de Daños
● ¿Qué clase de daños son predecibles?
● ¿Qué clase de estudios son necesarios para
predecir los daños?
● ¿Qué análisis es necesario?

8. La flota “Liberty”

9. La flota Liberty

10. La flota Liberty
● 2708 barcos
● 1031 daños o
accidentes

11. La flota Liberty
● 2708 barcos
● 1031 daños o
accidentes
● Brittle Failure of the U.S. Liberty Ship,Esso
Manhattan, March 29, 1943, New York
http://www.uh.edu/~pthompso/liberty/photos/fractu
res.html
,
● http://siamkaewkumsai.blogspot.com/2010_06_01_
archive.html
● The S.S. Schenectady (adapted from "Wikipedia
Commons"
http://en.wikipedia.org/wiki/SS_Schenectady, Al
Rosenfield)

13. La flota Liberty
● Totalmente soldados
● Esfuerzo triaxial
● Fractura frágil
● Temperatura de
Transición
● Ciclo térmico por
soldadura
(6/sept/2012) Soldando los barcos Liberty.
http://www.skylighters.org/troopships/welder.jpg

14. Crecimiento
● Concentración de esfuerzos creciente
● Rata de crecimiento creciente
● Resistencia residual decreciente

15. Cargas cíclicas y Resistencia Residual
2002.Broek, David. Elementary Engineering Fracture Mechanics. 4Th revied Ed. Kluwer. pp. 6.

16. Aparición de grietas
● Fallas pre-existentes
● Procesos de daño acumulativo
● Capacidad predictiva en el proceso del daño.

17. Modos de Falla
● Simple
● Cizallante
● Transverso

18. Estado de esfuerzos alrededor de
una grieta.
KI
σ ij = ⋅f ij (θ)
√(2 π R)

19. Estado de esfuerzos alrededor de
una grieta.
K I =β⋅σ⋅√(a)
β= √ (π)

20. Elementos Finitos
● Soluciones parcialmente polinomiales
● Continuas a trozos.
● Dependen de una malla.

21. Meshing