Integrated structural and electromagnetic optimisation of large terrestrial and space antenna structures

In this study, a novel multi-parameter overall situation optimisation method and mathematical model has been developed for use with terrestrial and space reflector antenna electro-mechanical systems and other metallic and polymer composite civil engineering structures. To satisfy extremely high design requirements, the proposed approach incorporates the objectives from various structural and electromagnetic (EM) performances of the system such as structural frequency, weight, stiffness, strength, reflector surface accuracy, antenna EM efficiency (gain), and radiation patterns at many working/loading cases simultaneously. The optimisation involves geometric and material design variables, and integrated design of composites and structural systems. Various terrestrial, launch and orbital working environments and loading cases which affect antenna performances have been included in the optimisation. These involve self-weight at different elevation attitudes, wind loading, random/dynamic loads and temperature distributions. Both truss and sandwich parabolic reflector panels with honeycomb core and carbon fibre laminate skins stiffened with composite ribs have been optimised. The effects of structural deformation on antenna EM performances have been investigated, modelled and repeatedly analysed in the iterative optimum-seeking procedure. Optical ray tracing, spline function aperture field interpolation, geometric optics aperture integration, Zernike modes analysis and FFT techniques have been used to analyse the EM performances of distorted reflector antennas. An important aspect of the work was the establishment of evaluation criteria in optimising engineering systems. A new method is presented, which can be used as a design review tool to assess the design quality of engineering systems. This systematic method quantitatively evaluates a design from multi-discipline and numerous points of view simultaneously for Pareto optimisation. A general purpose optimisation program MOST (Multifactor Optimisation of Structures Technique) has been developed to implement the proposed approach. MOST has the ability to utilise ABAQUS as an analysis routine for linear and non-linear, static and dynamic structural analysis in the optimisation procedures. Examples are presented to demonstrate the capabilities of the optimisation methodology and MOST program system. These examples are: an 8m Cassegrain antenna system, a 3.6x2.6m composite space deployable reflector antenna structure, and two 4m low side-lobe off-set antenna systems (with composite structures). The optimisation results for these antennas show that the optimisation procedures succeed in that at all the working/loading cases the antenna performances have been greatly improved.

[1]  J. Ruze.  Antenna tolerance theory—A review , 1966 .

[2]  Dietmar Scheulen.  Deployable 20/30 GHz reflector for future communications satellites , 1991 .

[3]  A. D. Searle,et al.  Low sidelobe reflector antenna design , 1997 .

[4]  Raphael T. Haftka,et al.  Integrated controls-structures optimization of a large space structure , 1992 .

[5]  R. Levy.  Computer design of antenna reflectors. , 1973 .

[6]  D. P. Hearth,et al.  Flexibility of space structures makes design shaky , 1985 .

[7]  Limitations on reflector antenna gain by random surface errors, pointing errors, and the angle-of-arrival jitter , 1990 .

[8]  S. R. Winegar,et al.  Interdisciplinary design analysis of a precision spacecraft antenna , 1985 .

[9]  Lucien A. Schmit,et al.  THE STRUCTURAL SYNTHESIS CONCEPT AND ITS POTENTIAL ROLE IN DESIGN WITH COMPOSITES , 1970 .

[10]  M. C. Bailey,et al.  A surface distortion analysis applied to the hoop/column deployable mesh reflector antenna , 1989 .

[11]  Singiresu S. Rao.  Game theory approach for multiobjective structural optimization , 1987 .

[12]  Bruce M. Irons,et al.  A frontal solution program for finite element analysis , 1970 .

[13]  Eric Sandgren.  Structural design optimization for latitude by nonlinear goal programming , 1989 .

[14]  Jaroslaw Sobieszczanski-Sobieski,et al.  MDO can help resolve the designer's dilemma. [multidisciplinary design optimization] , 1991 .

[15]  Somanath Nagendra,et al.  Composite Sandwich Structure Optimization with Application to Satellite Components , 1996 .

[16]  R. G. Helms,et al.  Lightweight Composite Mirror Analysis And Testing , 1989, Defense, Security, and Sensing.

[17]  R. N. Desmarais,et al.  Interpolation using surface splines. , 1972 .

[18]  Ben K. Wada,et al.  Advances in adaptive structures at Jet Propulsion Laboratory , 1993 .

[19]  J. Hedgepeth.  Critical requirements for the design of large space structures , 1981 .

[20]  Kent L. Lawrence,et al.  Optimum design of structures with multiple configurations with frequency and displacement constraints , 1990 .

[21]  Raphael T. Haftka,et al.  Stacking sequence optimization of simply supported laminates with stability and strain constraints , 1992 .

[22]  Garret N. Vanderplaats,et al.  An approximation method for configuration optimization of trusses , 1988 .

[23]  Jaroslaw Sobieszczanski-Sobieski,et al.  Sensitivity analysis and multidisciplinary optimization for aircraft design - Recent advances and results , 1990 .

[24]  Raphael T. Haftka,et al.  Integrated structural electromagnetic shape control of large space anatenna reflectors , 1989 .

[25]  Lucien A. Schmit,et al.  Optimum Structural Design with Dynamic Constraints , 1976 .

[26]  P. Mcgrail,et al.  Polymer composites for civil and structural engineering , 1993 .

[27]  Bin Wu,et al.  An improved strategy for GAs in structural optimization , 1996 .

[28]  A. Janiszewski,et al.  Optimal reconfiguration of thermally distorted wire mesh reflectors for large space antennas , 1988 .

[29]  J. S. Liu,et al.  Multi-Factor Optimisation of Large Reflector Antenna Structures , 1996 .

[30]  D. Bowles,et al.  Composite materials for space structures , 1985 .

[31]  Dimitris A. Saravanos,et al.  Multiobjective shape and material optimization of composite structures including damping , 1992 .

[32]  Kroo Ilan,et al.  Multidisciplinary Optimization Methods for Aircraft Preliminary Design , 1994 .

[33]  J. Hedgepeth.  Accuracy potentials for large space antenna reflectors with passive structure , 1982 .

[34]  Jack Vinson.  Optimal stacking sequences of composite faces for various sandwich panels and loads to attain minimum weight , 1988 .

[35]  Layne T. Watson,et al.  Improved Genetic Algorithm for the Design of Stiffened Composite Panels , 1994 .

[36]  Prabhat Hajela,et al.  Neural network approximations in a simulated annealing based optimal structural design , 1993 .

[37]  L. Hollaway,et al.  Large Space Structures - Their Implications and Requirements , 1991 .

[39]  Graham Thompson,et al.  The Multi-Factor Design Evaluation of Antenna Structures by Parameter Profile Analysis , 1996 .

[40]  N. T. Barrett,et al.  The structural setting and operation of large paraboloid radio antennae for optimum performance , 1969 .

[41]  C. Tseng,et al.  MINIMAX MULTIOBJECTIVE OPTIMIZATION IN STRUCTURAL DESIGN , 1990 .

[42]  Singiresu S Rao,et al.  Multiobjective optimization in structural design with uncertain parameters and stochastic processes , 1984 .

[43]  A.W. Rudge,et al.  Offset-parabolic-reflector antennas: A review , 1978, Proceedings of the IEEE.