Abstract
We propose to enforce positive definiteness of the Hessian matrix in a sequence of separable quadratic programs, without demanding that the individual contributions from the objective and the constraint functions are all positive definite. For problems characterized by non-convex objective or constraint functions, this may result in a notable computational advantage. Even though separable quadratic programs are of interest in their own right, they are of particular interest in structural optimization, due to the so-called ‘approximated-approximations’ approach. This approach allows for the construction of quadratic approximations to the reciprocal-like approximations used, for example, in CONLIN and MMA. To demonstrate some of the ideas proposed, the optimal topology design of a structure subject to local stress constraints is studied as one of the examples.
Notes
It is in fact in general not possible to develop analytical relationships between the primal and the dual variables for weight minimization problems subject to multiple constraints, should a dual method be opted for, e.g. see (Groenwold and Etman 2008).
If anything, the use of a continuation strategy seems to emphasize the computational advantage of exploiting non-convexity.
References
Bendsøe MP (1989) Optimal shape design as a material distribution problem. Struct Optim 1:193–202
Cheng G, Jiang Z (1992) Study on topology optimization with stress constraints. Engng Optim 20:129–148
Duysinx P, Bendsøe MP (1998) Topology optimization of continuum structures with local stress constraints. Int J Numer Meth Eng 43:1453–1478
Duysinx P, Zhang WH, Fleury C, Nguyen VH, Haubruge S (1995) A new separable approximation scheme for topological problems and optimization problems characterized by a large number of design variables. In: Ollhoff N, Rozvany GIN (eds) Proc. first world congress on structural and multidisciplinary optimization. Goslar, Germany, pp 1–8
Etman LFP, Groenwold AA, Rooda JE (2009) On diagonal QP subproblems for sequential approximate optimization. In: Proc. eighth world congress on structural and multidisciplinary optimization, paper 1065. Lisboa, Portugal, June
Etman LFP, Groenwold AA, Rooda JE (2012) First-order sequential convex programming using approximate diagonal QP subproblems. Struct Mult Optim 45:479–488
Fadel GM, Riley MF, Barthelemy JM (1990) Two point exponential approximation method for structural optimization. Struct Optim 2:117–124
Falk JE (1967) Lagrange multipliers and nonlinear programming. J Math Anal Appls 19:141–159
Fleury C (1979) Structural weight optimization by dual methods of convex programming. Int J Numer Meth Eng 14:1761–1783
Fleury C, Braibant V (1986) Structural optimization: a new dual method using mixed variables. Int J Numer Meth Eng 23:409–428
Groenwold AA (2012) On the linearization of separable quadratic constraints in dual sequential convex programs. Comput Struct. Available from Online First doi:10.1016/j.compstruc.2012.03.014
Groenwold AA, Etman LFP (2008) Sequential approximate optimization using dual subproblems based on incomplete series expansions. Struct Multidisc Optim 36:547–570
Groenwold AA, Etman LFP (2009) On the supremacy of reciprocal-like approximations in SAO - a case for quadratic approximations. In: Proc. eighth world congress on structural and multidisciplinary optimization, paper 1062. Lisboa, Portugal, June
Groenwold AA, Etman LFP (2010) A quadratic approximation for structural topology optimization. Int J Numer Meth Eng 82:505–524
Groenwold AA, Etman LFP (2011) SAOi: an algorithm for very large scale optimal design. In: Proc. ninth world congress on structural and multidisciplinary optimization, paper 035. Shizuoka, Japan, June
Groenwold AA, Etman LFP, Wood DW (2010) Approximated approximations for SAO. Struct Multidisc Optim 41:39–56
Groenwold AA, Wood DW, Etman LFP, Tosserams S (2009) Globally convergent optimization algorithm using conservative convex separable diagonal quadratic approximations. AIAA J 47:2649–2657
Groenwold AA, Etman LFP, Kok S, Wood DW, Tosserams S (2009) An augmented Lagrangian approach to non-convex SAO using diagonal quadratic approximations. Struct Multidisc Optim 38:415–421
Kirsch U (1990) On singular topologies in optimum structural design. Struct Optim 2:133–142
Nocedal J, Wright SJ (2006) Numerical Optimization. Springer Series in Operations Research and Financial Engineering, 2nd edn. Springer
Rozvany GIN (2001) On design-dependent constraints and singular topologies. Struct Multidisc Optim 21:164–172
Rozvany GIN, Zhou M (1991) Applications of COC method in layout optimization. In: Eschenauer H, Mattheck C, Olhoff N (eds) Proc. engineering optimization in design processes. Berlin, Springer-Verlag, pp 59–70
Svanberg K (1987) The method of moving asymptotes - a new method for structural optimization. Int J Numer Meth Eng 24:359–373
Svanberg K (2002) A class of globally convergent optimization methods based on conservative convex separable approximations. SIAM J Optim 12:555–573
Vanderplaats GN (2004) Very large scale continuous and discrete variable optimization. In: Proc. 10th AIAA/ISSMO Multidisciplinary Analysis and Optimization Conference, Albany, NY, U.S.A., August
Wood DW (2012) Dual sequential approximation methods in structural optimization. PhD dissertation, University of Stellenbosch, Stellenbosch, South Africa, Department of Mechanical and Mechatronic Engineering
Wood DW, Groenwold AA (2009) Non-convex dual forms based on exponential intervening variables, with application to weight minimization. Int J Numer Meth Eng 80:1544–1572
Wood DW, Groenwold AA (2010) On concave constraint functions and duality in predominantly black-and-white topology optimization. Comp Meth Appl Mech Eng 199:2224–2234
Zillober C (2002) SCPIP – an efficient software tool for the solution of structural optimization problems. Struct Multidisc Optim 24:362–371
Acknowledgements
I am grateful indeed to my former student, Dr. Derren W. Wood, for enlightening discussions about some of the intricacies associated with the singularities that arise due to local stress constraints.
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Groenwold, A.A. Positive definite separable quadratic programs for non-convex problems. Struct Multidisc Optim 46, 795–802 (2012). https://doi.org/10.1007/s00158-012-0810-8
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s00158-012-0810-8