Dynamical Integrity: A Novel Paradigm for Evaluating Load Carrying Capacity

An equivalent stiffness approach for modelling the behaviour of compression members according to Eurocode 3

The nonlinear dynamics of two archetypal structural systems exhibiting interactive modal post-buckling behavior is addressed, the discrete Augusti’s model and a reduced-order model of the axially loaded cylindrical shell. The uncoupled models exhibit a stable post-buckling response. However, the modal interaction leads to unstable post-buckling paths that entail a complex dynamic behavior and imperfection sensitivity, with a marked influence on the dynamic integrity and safety. Perfect and imperfect Augusti’s models are investigated in terms of static buckling, linear vibrations, nonlinear normal modes, local and global nonlinear response to harmonic excitation, dynamic integrity, control of global bifurcations aimed at increasing the load carrying capacity. Then, as an example of a continuous system exhibiting strong modal coupling and interaction, a two-degree-of-freedom model of the thin-walled cylindrical shell is investigated in terms of global behavior and dynamic integrity. The influence of uncertainties on the nonlinear response and dynamic integrity is also shortly addressed. The chapter shows how a judicious use of the tools of nonlinear dynamics sheds light on the actual safety of structural systems liable to unstable buckling under static and dynamic loads.

Free Vibrations of Composite Shallow Circular Cylindrical Shell Panels Stiffened by A Bonded Non-Central Shell Strip

The recent article by Burdisso and Fuller [‘‘Design of active structural acoustic control systems by eigenproperty assignment,’’ J. Acoust. Soc. Am. 96, 1582–1591 (1994)] does not fully illuminate the contributions of a number of prior authors for a crucial part of the work, that is, the development of weak radiator modes. This comment places the subject development of Burdisso and Fuller in context with the prior art. Further, it demonstrates the similarities of the subject development to prior work published by K. A. Cunefare [‘‘The minimum multimodal radiation efficiency of baffled finite beams,’’ J. Acoust. Soc. Am. 90, 2521–2529 (1991)]. The authors recognize and acknowledge that Burdisso and Fuller’s implementation of the concept, through eigenproperty assignment, is unique and valuable.

An integrated design method for a mechanical structure and controller using the Nash bargaining game is proposed. In this study, we describe how to apply the bargaining game model into the design of mechanical systems and show that optimized design parameters can be obtained from the strategy which maximizes the Nash product. The example application shown in this paper is the design of a single link flexible arm. In this sample design, the lowest natural frequency and the real part of the dominant pole of system with PD controller are considered as indices to optimize both the structure and controller. Results show that we can design a flexible arm with PD controller can be designed using this method.

The dynamic analysis of a structural system with different material and geometric properties leads to linear eigenvalue problem such as generalized (or standard) eigenvalue problem. In general, the material and geometric properties are assumed to be in the form of crisp (or exact). However, due to several errors and insufficient or incomplete information of data, the uncertainties are assumed to be present in the material and geometric properties. These uncertain material and geometric properties may be modeled through convex normalized fuzzy sets. In standard fuzzy arithmetic, all the operands are assumed to be independent of each other. But when they are partially or completely dependent on each other, the standard fuzzy arithmetic results in a wider range. This situation is known as the “dependency problem” or “overestimation problem”. In this regard, a fuzzy-affine approach is developed to overcome the dependency problem. This proposed approach may improve the outer enclosures and give tighter bounds to the fuzzy solution set. This chapter deals with the dynamic analysis of various structural systems viz. multi degrees-of-freedom spring-mass structural system, multi-storey frame structural system, etc. by adopting the proposed approach. Several numerical examples related to the dynamic analysis of these structural systems have been worked out to illustrate the reliability and efficiency of the present approach.KeywordsAffine arithmeticFuzzy-affine arithmeticDynamic analysis of structural systemFuzzy generalized eigenvalue problemFuzzy standard eigenvalue problem

Recently, a structural optimization design system linked with a FEM analysis system is going to be useful for a structural design, by a radical development of a computer environment. But, when structural engineers use this design system in practice, complicated operations are required to make an input-data. So this design system is not “a Practical Tool” for designers, we have to develop the structural optimization design system which is used easily for designers.Authors research the CIM for shipbuilding and develop a prototype CIM system. We call this system SODAS (System Of Design and Assembling for Shipbuilding). In the SODAS, designers can design a ship structure by design parameters and evaluate a designed structure by FEM directly.In this study, authors try to integrate a commercial structural optimization design system (GENESIS : which is developed in NASA) with the SODAS. We make relations clear between design parameters in the SODAS and design variables in the structural optimization design system. And we propose the method of system integration used by these relations. In the concrete, we develop the structural optimization design system based on the Product Model which supports designers powerfully by presenting optimal design-values.

Graphic Statics offers a geometrical framework for the design & analysis of structural systems with reciprocity between the ‘form’ and ‘force’ diagrams being a fundamental notion. In this paper we provide a detailed illustration and explanation of Maxwell’s reciprocal construction for 2-dimensional trusses through a 3-dimensional paraboloid of revolution. Even though Maxwell briefly mentions this method there is no record of the detailed construction. The main focus of this research is placed on the synthesis of Poncelet duality in projective geometry and of reciprocity in graphic statics resulting in the definition of a generalised dual statement for the construction of reciprocal diagrams (Maxwell 2D & Rankine 3D). This is based on the construction of their higher dimensional polyhedral Airy stress functions, using conic sections. We generalise the construction for other conics, such as the sphere and ellipsoid, and we extend the definition for 3-dimensional trusses and corresponding higher-dimensional conic sections.

Stochastic model updating using distance discrimination analysis

SAP2000 is well-known commercial software for analysis and design of structural systems that is equipped with an open application programming interface (OAPI). In this work, a code written in C# able to solve three-dimensional topology optimization problems is presented, where a topology optimization framework was integrated into SAP2000 taking advantage of its OAPI feature. The code is partially based on the 99 and 88 line codes written by Sigmund (Struct Multidiscip Optim 21(2):120–127, 2001) and Andreassen et al. (Struct Multidiscip Optim 43(1):1–16, 2011). The code solves the problem of minimum compliance while through OAPI it takes advantage of all modelling capabilities of SAP2000. The paper covers the theoretical aspects of topology optimization incorporated in the code and provides detailed description of their numerical implementations. Special effort was made to the latter one, describing in detail all numerical aspects of the code, in order to facilitate the reader to understand the code, and therefore being able to further enhance its capabilities. The complete code can be downloaded from GitHub ( https://github.com/nikoslagaros/TOCP ).

An application of fuzzy mathematical programming techniques to multiple objective design problems is presented. Two examples dealing with the multiobjective design of mechanical and structural systems are considered. The concept of a Pareto-optimal and fuzzy Pareto-optimal solution is discussed, and it is shown that the resulting formulation yields Pareto-optimal solutions. The fundamental assumption in fuzzy mathematical programming applications involving the use of linear membership functions is critically examined. Several nonlinear shapes for the membership functions of the fuzzy sets are proposed, consistent with varying perceptions of the designer, and are analyzed to determine their impact on the overall design process. These shapes correspond to what we define as the coefficient of membership satiation. It is seen that optimum designs for both examples are strongly influenced by the sign of the membership satiation coefficient.

Discusses the capabilities of a mathematical tool useful in the simulation of physical and diagnostic reasoning, particularly with application to smart structures logic. More precisely, a few sample problems in structural analysis and control are formulated and solved arithmetically in terms of interval-valued variables, i.e. in terms of variables that can take any numerical value within a given set. Interval variables can also be used to represent uncertainties of a nonprobabilistic nature and enable the formulation of semi-qualitative physical models consistent with typical reasoning paradigms, where the ability to discern between different behavioural states and causal paths is an important feature.

Results of survey of use of SSADM in commercial and government sectors in United Kingdom

This paper presents a prototype for a structural analysis and design system by using the STEP for the representation and exchange of information on steel structures, by integrating the product model of steel framed structures of AP 230, the geometric and topological information of Part 42, and the detailed Finite Element Analysis information of Part 104 into an unified system. Thus, the STEP-based system makes engineering information more clearable and exchangeable between computer applications than any other conventional methods. This system may be further extended to incorporate such computer applications as detailed engineering and manufacturing information on steel structures.

Modified subset simulation method for reliability analysis of structural systems