Critical Crack Size Investigation Method for a Land Launcher


  • Ali Yetgin Research & Development Department, Roketsan, Turkey
  • A. Acar Research & Development Department, Roketsan, Turkey
  • S. Kadıoğlu Department of Mechanical Engineering, Middle East Technical University, Turkey



fracture mechanics, weld, finite element,, launcher, structural integrity


Structural integrity evaluation of military systems is vital in such applications as rocket launchers. In safe life design, for a certain operational life the system is ensured to function well and no failure would occur even in the presence of some imperfections or flaws. This paper considers the fracture analysis as part of the safe life design approach that is used in the design of a rocket launcher. A methodology based on sub modelling technique is introduced. It was made sure that unstable crack growth would not occur upto certain crack sizes. Subsequently, after actual manufacturing of the launcher, critical locations of welds in the system were checked for presence of any cracks after repeated firing loads. After these controls no cracks were detected due to operational conditions until the time when this document was prepared.

Author Biography

Ali Yetgin, Research & Development Department, Roketsan, Turkey

Senior structural analysis engineer

MSc and BSc in Mechanical Engineering


US Army Weapon Systems Handbook. Washington: OASA, 1999.

WANG, C.H. Introduction to Fracture Mechanics. DSTO Aeronautical and Maritime Research Laboratory Melbourne, DSTO-GD-0103, 1996.

ABAQUS® Documentation v6.12.

DIAMANTOUDIS, A.Th. and LABEAS, G.N. Stress Intensity Factors of Semi‐elliptical Surface Cracks in Pressure Vessels by Global‐local Finite Element Methodology. Engineering Fracture Mechanics, 2005, vol. 72, no. 9, p.1299-1312.

GIGLIO M. and MANES A. Crack Propagation on Helicopter Panel: Experimental Test and Analysis. Engineering Fracture Mechanics, 2008, vol. 75, no. 3‐4, p. 866-879.

ACAR, B., YETGIN, A. and KADIOGLU S. Dynamic Finite Element Analysis of a Cradle System. In 84th Shock and Vibration Symposium, 2013.

ANDERSON, T.L. Fracture Mechanics: Fundamentals and Applications. 3rd edition. Boca Raton: Taylor & Francis, 2005.

ACAR, B. Finite element analysis of fracture mechanics problems [Master’s Thesis], Ankara: Middle East Technical University, 1997.

YETGIN, A. Fracture Analysis of Welded Connections [Master Thesis]. Ankara: Middle East Technical University, 2013.




How to Cite

Yetgin, A., Acar, A., & Kadıoğlu, S. (2018). Critical Crack Size Investigation Method for a Land Launcher. Advances in Military Technology, 13(1), 119–131.



Research Paper