Drill Hole Optimization for Augmenting Structural Integrity
Keywords:Stress intensity factor, photoelasticity, finite element method, drill hole, optimization
Structures develop cracks during the course of there life resulting in catastrophic failures. This can be reduced by drilling holes near the crack tip. Here the aspect of optimal position and size of the drill hole has been analysed. Additionally the effect of supplementary hole has also been made. Finite element code ANSYS was used for the analysis. To verify the fracture capabilities of ANSYS the results were corroborated using photoelastic techniques. It was observed that reduction in stress intensity factor to a great extent depends upon the position of the stop hole. Also it was observed that as the radius of the crack was increased the stress intensity factor increased. Creating supplementary hole further reduced the stress intensity factor. So it can be concluded that for employing the concept of drill hole its position and size should be accurately determined.
Domazet Z. Comparison of fatigue crack retardation methods. Eng Fail Anal 1996;3(2):137–47.
Elber W. Fatigue crack closure under cyclic tension. Eng Fract Mech 1970;2:37–45.
Sharp PK, Clayton JQ, Clark G. Retardation and repair of fatigue cracks by adhesive infiltration. Fatigue Fract Eng Mater Struct 1997;20(4): 605–14.
Shin CS, Cai CQ. A model for evaluating the effect of fatigue crack repair by the infiltration method. Fatigue Fract Eng Mater Struct 2000;23:835–45.
Ayatollahi MR, Hashemi R. Mixed mode fracture in an inclined center crack repaired by composite patching. Compos Struct 2007;81:264–73.
Mendez PF, Eagar TW. Penetration and defect formation in high-current arc welding. Weld J 2003;82(10):296–306.
Liu C, Northwood DO, Bhole SD. Tensile fracture behavior in CO2 laser beam welds of 7075-T6 aluminum alloy. Mater Des 2004;25:573–7.
Song PS, Shieh YL. Stop drilling procedure for fatigue life improvement. Int J Fatigue 2004;26:1333–9.
Ghfiri R, Shi H, Guo R, Mesmacque G. Effects of expanded and non-expanded hole on the delay of arresting crack propagation for aluminum alloys. Mater Sci Eng 2000;A286:244–9.
Ghfiri R, Amrouche A, Imad A, Mesmacque G. Fatigue life estimation after crack repair in 6005 AT-6 aluminum alloy using the cold expansion hole technique. Fatigue Fract Eng Mater Struct 2000;23:911–6.
Ayatollahi et al., Mixed mode fatigue crack initiation and growth in a CT specimen repaired by stop hole technique. Engg. Fract. Mech. 145, 2015, 115-127.
James W Dally.
Gope et al., Influence of crack offset distance on interaction of multiple collinearand offset edge cracks in a rectangular plate. The.& Appl. Fract. Mech., 2014, 19–29.
R.J. Sanford, J.W. Dally, A general method for determining mixed mode stressintensity factors, Eng. Fract. Mech. 4 (1972) 357–366.
K. Ramesh, S. Gupta, A.A. Kelkar, Evaluation of stress field parameters infracture mechanics by photoelasticity-revisited, Eng. Fract. Mech. 56 (1997) 25–45.
V.K. Singh, P.C. Gope, Photoelastic determination of mixed mode stressintensity factor, J. Solid Mech. 3 (2009) 233–244.
P.C. Gope, A. Thakur, Experimental investigation of crack growth directions in multiple crack problems, Fatigue Fract. Eng. Mater. Struct. 34 (2011) 804–815.
V.K. Singh, P.C. Gope, Experimental evaluation of mixed mode stress intensity factor for prediction of crack growth by phoelastic method, J Failure Anal. Prevent. 13 (2013) 217–226.