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Improving productivity in finite element analysis through interactive processing
Lee, H P, Harris, P J and Hsu, C 'A nonlinear finite element computer program for thin-walled members' Thin-WalledStructures Vol 2 No 4 (1984) p 355 A nonlinear finite element computer program for analysis of thin-walled metal structural members is presented. The program has the ability to handle both geometrical and material nonlinearities. Marguerre's shallow shell theory is adopted for the straindisplacement relationships. A bendingmembrane rectangular element with six degrees of freedom at each node is used in the program. The formulation is based on a total Lagrangian coordinate system and the flow theory of plasticity. Sussman, T and Bathe, K 'Studies of Finite Element Procedures - On Mesh Selection' Comput. 5truer. Vol 21 No 1/2 (1985) p 257 This is a tutorial paper on the selection of a finite element mesh in engineering practice. First, basic concepts are discussed which identify whether a finite element mesh has provided an accurate solution for a linear elastic static analysis, and thus when mesh refinement is necessary. These concepts are then considered in a finite element analysis of a pressure vessel subjected to an internal pressure load. Woodward, W S and Morris, J W 'Improving productivity in finite element analysis through interactive processing' Finite Elements In Analysis and Design Vol 1 No 1 (April 1985) pp 3 5 - 4 8 This paper discusses concepts which form the basis for improving productivity in finite element analysis through the use of interactive graphical pre- and postprocessing. Examples are presented which illustrate the costs and benefits of this technology. In particular, the cost required to perform an analysis is said to be reduced to such an extent that the cost of user training and inexpensive colour terminals can be recovered after the analysis of three or four moderate sized problems. Stolfo, S J 'Is CADCAM ready for AI?' Finite Elements in Analysis and Design Vol 1 No 2 (August 1985) pp 141-151 This paper explores the possibility of mergingCADCAM with Artificial Intelligence technology. A brief tutorial on expert systems is presented. Several observations are noted which link existing expert system applications with various CADCAM problems. The authors conclude that present Artificial Intelligence techniques can in the near future be implemented to drastically improve present CADCAM capabilities. Tang, Limin and Liu, Yingxi 'Quasi-conforming element techniques for penalty finite element methods' Finite Elements in Analysis and Design Vol 1 No 1 (1985) pp 2 5 - 3 3 The Quasi-Conforming Element (QCE) technique is introduced in this paper for
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calculation penalty finite element problems. Unlike the reduced integration methods, the QCE technique uses multiple sets of functions to approximate strains and is independent of the integration order. Examples of the use of this technique are given for incompressible linear elasticity and medium thickness plate bending. The related generalized variational principle is presented. Bergan, P G, Mollestad, E and Sandsmark, N 'Nonlinear static and dynamic response analysis for floating offshore structures' Eng. Comput. Vol 2 No 1 (March 1985) p 13 A method for nonlinear static and dynamic analysis of flexible systems submerged in water is outlined. The systems considered include cable and beam elements, as well as buoys and clump weights. Contact and liftoff between members and the sea floor are accounted for. The formulation allows for large deformations and material nonlinearities. Hydrostatic buoyancy and hydrodynamic drag forces are considered throughout the analyses. Bergan, P G and Mollestad, E 'An automatic time-stepping algorithm for dynamic problems' Computer Methods in Applied Mechanics and Engineering Vol 49 No 3 (June 1985) p 299 This paper discusses algorithms for automatic computation of time steps in discrete integration of dynamic problems. Objective criteria for performance and guidelines for making an algorithm practically applicable are suggested. A set of parameters for characterizing the dynamic response of a system is proposed, including a 'current frequency', a 'current period' and a 'dynamic stiffness parameter'. The automatic computation of the time step based on the current period is proposed. Nicklin, P J, Powell, G H and Hollings, J P ' Hierarchical data man agemen t for stru ctu ral analysis' Engineering with Computers Vol 1 No 1 (1985) p 45 This paper reviews data base requirements and the organization of integrated computer program networks. It identifies a need for hierarchical data base management in computer programs for structural analysis. The nature of the data hierarchy is illustrated with reference to a building that has been analyzed by using substructure techniques. The organization and features of a certain hierarchical data base manager are then described. McGuire, W and Castafier, J L 'Computeraided limit states design' Prec. Third Conference on Steel Developments Australian Institute of Steel Construction, Melbourne, Australia (May 2 0 - 2 2 1985) In this paper, a computer-aided analysis/ design system for s$eel frames is described. The emphasis of the work is on 3D structures and nonlinear behaviour. The manner in
which the system may be employed with a limit states specification, the new Load and Resistance Factor Design Specification of the American Institute of SteelConstruction is illustrated. Also, a series of illustrations is used to explain the authors' approach to computer-aided design. Lastly, prospects of the future of CAD in steel frame analysis are presented. Smith, T, Gierlinski, J and Walker, B 'A combined finite strip/finite element method for analysing thin-walled structures' ThinWalledStruct. Vol 3 No 2 (1985) p 163 A combined finite-strip/finite element method is presented for the linear elastic analysis of thin-walled structures containing transverse diaphragms and intermediate supports. It is proposed to discretize a prismatic 'main structure' with finite strips and a nonprismatic 'substructure' by finite elements, the two being connected by appropriate compatibility conditions. As a consequence of combining finite strips and finite elements, the stiffness matrix loses the decoupling between the harmonics that is the basis of the efficiency of the finite strip method. However, decoupling within the submatrix for the prismatic main structure is still used by a multilevel block iterative solution method. Buyukozturk, Oral and Shareef, Syed Sarwar 'Constitutive modelling of concrete in finite element analysis' Comput. 5truer. Vol 21 No 3 (1985) pp 5 8 1 - 6 1 0 This paper reviews the approaches generally used in defining constitutive relations for concrete. Constitutive models based on isotropic elastic, orthotropic elastic, and plasticity formulations are discussed in detail. A computer program developed for 3D finite element analysis of complex reinforced, prestressed, and refractory concrete systems is described. The program incorporates nonlinear material properties, cracking in concrete, shear transfer in cracked reinforced concrete sections, and time dependent effects such as creep, shrinkage and transient temperature distributions. Watwood, V B 'Gable frame design considerations' J. Struct. Eng. ASCE Vo1111 No 7 (July 1985) p 1543 A gable frame design is reviewed with regard to the modelling, load specification, and strength evaluation. It is found that the frame behaviour may be sensitive to variations in the boundary conditions at the column bases, and that it is prudent to consider several reasonable alternatives and to construct an envelope of internal forces for design. It is shown that uneven loading should also be considered in the design. The question of the correct effective length for the rafter is also examined. It is suggested that if there is significant axial stress in the rafter, caution should be exercised in the use of specification provisions, which are based on zero axial stress in the girders.
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calculation penalty finite element problems. Unlike the reduced integration methods, the QCE technique uses multiple sets of functions to approximate strains and is independent of the integration order. Examples of the use of this technique are given for incompressible linear elasticity and medium thickness plate bending. The related generalized variational principle is presented. Bergan, P G, Mollestad, E and Sandsmark, N 'Nonlinear static and dynamic response analysis for floating offshore structures' Eng. Comput. Vol 2 No 1 (March 1985) p 13 A method for nonlinear static and dynamic analysis of flexible systems submerged in water is outlined. The systems considered include cable and beam elements, as well as buoys and clump weights. Contact and liftoff between members and the sea floor are accounted for. The formulation allows for large deformations and material nonlinearities. Hydrostatic buoyancy and hydrodynamic drag forces are considered throughout the analyses. Bergan, P G and Mollestad, E 'An automatic time-stepping algorithm for dynamic problems' Computer Methods in Applied Mechanics and Engineering Vol 49 No 3 (June 1985) p 299 This paper discusses algorithms for automatic computation of time steps in discrete integration of dynamic problems. Objective criteria for performance and guidelines for making an algorithm practically applicable are suggested. A set of parameters for characterizing the dynamic response of a system is proposed, including a 'current frequency', a 'current period' and a 'dynamic stiffness parameter'. The automatic computation of the time step based on the current period is proposed. Nicklin, P J, Powell, G H and Hollings, J P ' Hierarchical data man agemen t for stru ctu ral analysis' Engineering with Computers Vol 1 No 1 (1985) p 45 This paper reviews data base requirements and the organization of integrated computer program networks. It identifies a need for hierarchical data base management in computer programs for structural analysis. The nature of the data hierarchy is illustrated with reference to a building that has been analyzed by using substructure techniques. The organization and features of a certain hierarchical data base manager are then described. McGuire, W and Castafier, J L 'Computeraided limit states design' Prec. Third Conference on Steel Developments Australian Institute of Steel Construction, Melbourne, Australia (May 2 0 - 2 2 1985) In this paper, a computer-aided analysis/ design system for s$eel frames is described. The emphasis of the work is on 3D structures and nonlinear behaviour. The manner in
which the system may be employed with a limit states specification, the new Load and Resistance Factor Design Specification of the American Institute of SteelConstruction is illustrated. Also, a series of illustrations is used to explain the authors' approach to computer-aided design. Lastly, prospects of the future of CAD in steel frame analysis are presented. Smith, T, Gierlinski, J and Walker, B 'A combined finite strip/finite element method for analysing thin-walled structures' ThinWalledStruct. Vol 3 No 2 (1985) p 163 A combined finite-strip/finite element method is presented for the linear elastic analysis of thin-walled structures containing transverse diaphragms and intermediate supports. It is proposed to discretize a prismatic 'main structure' with finite strips and a nonprismatic 'substructure' by finite elements, the two being connected by appropriate compatibility conditions. As a consequence of combining finite strips and finite elements, the stiffness matrix loses the decoupling between the harmonics that is the basis of the efficiency of the finite strip method. However, decoupling within the submatrix for the prismatic main structure is still used by a multilevel block iterative solution method. Buyukozturk, Oral and Shareef, Syed Sarwar 'Constitutive modelling of concrete in finite element analysis' Comput. 5truer. Vol 21 No 3 (1985) pp 5 8 1 - 6 1 0 This paper reviews the approaches generally used in defining constitutive relations for concrete. Constitutive models based on isotropic elastic, orthotropic elastic, and plasticity formulations are discussed in detail. A computer program developed for 3D finite element analysis of complex reinforced, prestressed, and refractory concrete systems is described. The program incorporates nonlinear material properties, cracking in concrete, shear transfer in cracked reinforced concrete sections, and time dependent effects such as creep, shrinkage and transient temperature distributions. Watwood, V B 'Gable frame design considerations' J. Struct. Eng. ASCE Vo1111 No 7 (July 1985) p 1543 A gable frame design is reviewed with regard to the modelling, load specification, and strength evaluation. It is found that the frame behaviour may be sensitive to variations in the boundary conditions at the column bases, and that it is prudent to consider several reasonable alternatives and to construct an envelope of internal forces for design. It is shown that uneven loading should also be considered in the design. The question of the correct effective length for the rafter is also examined. It is suggested that if there is significant axial stress in the rafter, caution should be exercised in the use of specification provisions, which are based on zero axial stress in the girders.
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