A genetic algorithm applied to optimisation of patch repairs for cracked plates

The problem of the optimal shape of patch repairs for cracked plates is here examined by applying a biology-based method, known as the genetic algorithm. The optimum design procedure consists in evaluating the patch topology which maximises or minimises some mechanical properties of the repaired plate while keeping constant the total patched area (constrained optimisation problem). In the present paper, the best patch shape is determined by minimising the stress-intensity factor function (which is the adopted objective function). The proposed procedure is implemented in a finite element code, and some numerical simulations are carried out in order to assess the reliability of the method when applied to the case of a cracked plate under Mode I. For some configurations analysed, the stress-intensity factor can significantly be reduced by employing an optimal shape patch instead of a simple shape (square or rectangular) patch.

[1]  Jin-Rae Cho,et al.  Volume fraction optimization for minimizing thermal stress in Ni–Al2O3 functionally graded materials , 2002 .

[2]  Bernard Gross,et al.  Stress-Intensity Factors for Single-Edge-Notch Specimens in Bending or Combined Bending and Tension by Boundary Collocation of a Stress Function , 1965 .

[3]  D. A. Zacharopoulos.  Arrestment of cracks in plane extension by local reinforcements , 1999 .

[4]  Hugh A. Bruck,et al.  Enhancing the optimization of material distributions in composite structures using gradient architectures , 2003 .

[5]  Antonio Mancuso,et al.  A genetic algorithm for combined topology and shape optimisations , 2003, Comput. Aided Des..

[6]  Wing Kong Chiu,et al.  Composite repairs to rib stiffened panels , 1999 .

[7]  Tarek I. Zohdi,et al.  Constrained inverse formulations in random material design , 2003 .

[8]  Shyan Bob Shen,et al.  Fatigue analysis of cracked thick aluminum plate bonded with composite patches , 2004 .

[9]  H. Mlejnek,et al.  An engineer's approach to optimal material distribution and shape finding , 1993 .

[10]  D. Ouinas,et al.  4027 - COMPARISON OF DOUBLE AND SINGLE BONDED REPAIRS TO SYMMETRIC COMPOSITE STRUCTURES: A NUMERICAL ANALYSIS , 2004 .

[11]  David E. Goldberg,et al.  Genetic Algorithms in Search Optimization and Machine Learning , 1988 .

[12]  M. Bendsøe,et al.  Generating optimal topologies in structural design using a homogenization method , 1988 .

[13]  R. Haftka,et al.  Structural shape optimization — a survey , 1986 .

[14]  Lawrence. Davis,et al.  Handbook Of Genetic Algorithms , 1990 .

[15]  K. R. Leimbach,et al.  Interactive shape optimization of continuum structures , 1997 .

[16]  D. Bond,et al.  Principles and practices of adhesive bonded structural joints and repairs , 1999 .

[17]  Ying-Te Lee,et al.  Stress intensity factor of a patched crack , 1997 .

[18]  Nelson F. F. Ebecken,et al.  Optimization of mass concrete construction using genetic algorithms , 2004 .

[19]  Ranga Pitchumani,et al.  Application of genetic algorithms to optimal tailoring of composite materials , 1998 .

[20]  I. L. Lim,et al.  On stress intensity factor computation from the quarter‐point element displacements , 1992 .

[21]  J. Rice,et al.  Elementary engineering fracture mechanics , 1974 .

[22]  A. Muc,et al.  Genetic algorithms and finite element analysis in optimization of composite structures , 2001 .

[23]  Makoto Ishida.  Arbitrary Symmetric Loading Problems of Centrally Cracked Rectangular Plates , 1976 .

[24]  Ren-Jye Yang,et al.  Optimal topology design using linear programming , 1994 .

[25]  A. Mahadesh Kumar,et al.  Optimum design of symmetric composite patch repair to centre cracked metallic sheet , 2000 .

[26]  Christine M. Anderson-Cook,et al.  A genetic algorithm with memory for mixed discrete–continuous design optimization , 2003 .