PSI - Issue 71

Arun K. Singh et al. / Procedia Structural Integrity 71 (2025) 90–94

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It is important to note the key mechanism of increasing total surface energy with crack velocity is crack branching (Freund, 1998; Crump et al., 2017; Lee and Prakash, 1998). As mentioned earlier, that kinetic energy of crack tip becomes significant with increasing crack velocity to result in rapid increase of DSIF. And this may also result in catastrophic failure if DSIF exceeds critical DSIF of the solid. Finally, future study includes more validation of the proposed fracture model on different solids such as soft polymers and adhesives (Kobayashi and Yang, 1987). Moreover, it would also be interesting to validate the proposed fracture model in view of DSIF estimated using instrumented

Charpy impact test. 4.0 Conclusions:

The present dynamic fracture model enables correlating dynamic surface energy of the steel material (AISI 4340) as function of crack velocity. The fracture model is also able to predict asymptotic behaviour of dynamic stress intensity factor at a critical velocity. This observation is attributed to crack branching at low crack velocity and inertia of crack tip at high crack velocity. References Crump, T., Ferté, G., Jivkov, A., Mummery, P. and Tran, V.X., 2017. Dynamic fracture analysis by explicit solid dynamics and implicit crack propagation.International Journal of Solids and Structures, 110, 113-126. Freud, L.B., 1998. Dynamic fracture mechanics. Cambridge university press. Griffith, A.A., 1921. VI. The phenomena of rupture and flow in solids. Philosophical transactions of the royal society of london. Series A, containing papers of a mathematical or physical character, 221,.163-198. Kobayashi AS, Yang KH.,1987 Dynamic stress intensity factor versus crack velocity relation. In Advanced Materials for Severe Service Applications. 51-60 Dordrecht: Springer Netherlands. Lee, Y. and Prakash, V., 1998. Dynamic fracture toughness versus crack tip speed relationship at lower than room temperature for high strength 4340VAR structural steel. Journal of the Mechanics and Physics of Solids, 46,1943-1968. Landis, C.M., Pardoen, T. and Hutchinson, J.W., 2000. Crack velocity dependent toughness in rate dependent materials. Mechanics of materials, 32, 663-678. Mott, N.F., 1948. Fracture of metals: theoretical considerations. Engineering, 165, 16-18. Neal-Sturgess, C., 2012. Analysis of fracture and fatigue using a simplified stress wave unloading model and Lagrangian mechanics – version 2. https://arxiv.org/abs/1212.6704v2 Melker, A.I., 2010. Cracks: challenge to physics. Materials Physics and Mechanics, 9,111-134. Rosakis, A.J., Duffy, J. and Freund, L.B., 1984. The determination of dynamic fracture toughness of AISI 4340 steel by the shadow spot method. Journal of the Mechanics and Physics of Solids, 32, 443 460. Stampfl, J. and Kolednik, O., 2000. The separation of the fracture energy in metallic materials. International Journal of Fracture, 101,321-345. Zhou, F., Molinari, J.F. and Shioya, T., 2005. A rate-dependent cohesive model for simulating dynamic crack propagation in brittle materials. Engineering fracture mechanics, 72,1383-1410. https://in.mathworks.com/help/optim/ug/lsqcurvefit.html