An expert system for preliminary numerical design modelling

This paper is based upon the premise that computers can do more than just ‘number crunching’ to assist a designer in his task. Key features of the design process where traditional computer-aided design (CAD) approaches have had limited success are presented. The approach of expert systems, which shows promise of assisting in these features, is outlined and a system based on this approach, DESIGNER, described. This system can be applied to any numerical design problem and is illustrated through an example from preliminary ship design.     

An expert system for the design and selection of ball bearing parameters

Artificial Intelligence (AI) is an emerging technology. Research in Al is focused on developing computational approaches to intelligent behaviour.The computer programs with which AI could be associated are primarily processes associated with complexity, ambiguity, indecisiveness, and uncertainty. One of these computer programs is referred to as Knowledge-based Expert System (KBES) as it represents knowledge acquired from various experts in a particular field of interest to the user. The expert system emulates human behaviour in solving problems thought to require experts for their solution by utilizing computer programs that incorporate experts' heuristic reasoning. In this paper, the application of KBES to aid the design of ball and roller bearing is discussed. The precision rolling-element bearing of the twentieth century is a product of exacting technology and sophisticated science. A bearing supports radial and axial loads, at the same time allowing relative motion between two elements of a machine. Various requirements and steps in the design of ball and roller bearings are discussed. Equations are developed for the relevant design parameters and input into the expert system shell called VP-Expert. The expert system rules are also provided.     

小型组合式冷库设计专家系统

冷库设计中存在大量的符号推理及经验数据的选取，传统程序只能处理精确数据，而对符号推理和非精确性数据无能为力。采用专家系统模型，运用模糊逻辑方法，结合小型组合式冷库的设计实例，模拟专家进行冷库设计中符号推理及选取经验数据，得到了较好的设计结果。     

FMS Designer: An expert system for flexible manufacturing system design

Implementation of flexible manufacturing technology in the batch manufacturing environment has created major problems for designers and engineers who are responsible for specification and design of flexible manufacturing systems (FMS). The FMS design task appears to be an excellent application for expert systems techniques. This paper describes current results of an ongoing research effort to develop an expert system which analyses the output from an FMS simulation model, determines whether operational and financial objectives are met, identifies design deficiencies or opportunities for improvement, and proposes designs which overcome deficiencies or exploit improvement opportunities. An overview of the FMS design expert system is given and a case study is presented to illustrate how the system operates. Areas for future research are also discussed.     

产品设计专家系统研究

介绍了产品设计的目的和任务,信息时代的产品设计发展状况及存在的问题,讨论了将人工智能理论与专家系统技术应用于产品设计领域,提出一个产品设计专家系统的框架结构.利用智能代理技术实现了信息与资料的整理,依据形态分析法实现了辅助创新设计,并提出采用数学建模法进行产品方案的评定.     

An expert system based approach to manufacturing cell design

The design of cellular systems is a complex, multi-criteria and multi-step process which can have significant implications for the entire organization. Most research in this area focuses on the formation of pan families and associated machine groups, one step in the cell design process. Numerous quantitative techniques have been developed to address this part-family/machine group formation problem. Existing approaches include math programming, algorithms for matrix diagonalization, the application of network modelling and the use of similarity coefficients. These mathematically-oriented techniques can handle a relatively limited set of quantitative objectives and. in addition, require many simplifying assumptions. For this reason, the solutions generated by these techniques are of limited usefulness in actual cell design. This paper proposes an expert system approach to cell system design. The starting point for the expert system is the initial solution generated by traditional mathematical techniques. Based on a flexible set of user-driven quantitative and qualitative factors, the expert system evaluates these preliminary solutions for feasibility and quality. If the solutions are not satisfactory (infeasible or of low quality), the system suggests modifications.     

Geometrically nonlinear composite beam structures: design sensitivity analysis

The purpose of this paper is to develop a finite element model for optimal design of composite laminated thin-walled beam structures, with geometrically nonlinear behavior, including post-critical behavior. A continuation paper will be presented with design optimization applications of this model. The structural deformation is described by an updated Lagrangean formulation. The structural response is determined by a displacement controlled continuation method. A two-node Hermitean beam element is used. The beams are made from an assembly of flat-layered laminated composite panels. Beam cross-section mass and stiffness property matrices are presented.

Design sensitivities are imbedded into the finite element modeling and assembled in order to perform the structural design sensitivity analysis. The adjoint structure method is used. The lamina orientation and the laminate thickness are selected as the design variables. Displacement, failure index, critical load and natural frequency are considered as performance measures. The critical load constraint calculated as the limit point of the nonlinear response is also considered, but a new method is proposed, replacing it by a displacement constraint.     

An expert system for the optimal mesh design in the hp-version of the finite element method

This paper suggests a simple expert system frame and provides the domain knowledge for the optimal mesh design and the prediction of the error in the energy norm for the problem of plane elasticity using the hp-extension in the finite element method. The expert system monitors the progress of the analysis, guides the user through the various steps and is able to reason about its own advice. In an example the user–expert communication is shown and the superiority of the results is demonstrated.     

Lightweight design and crash analysis of composite frontal impact energy absorbing structures

Carbon fibre composites have shown to be able to perform extremely well in the case of a crash and are being used to manufacture dedicated energy-absorbing components, both in the motor sport world and in constructions of aerospace engineering. While in metallic structures the energy absorption is achieved by plastic deformation, in composite ones it relies on the material diffuse fracture. The design of composite parts should provide stable, regular and controlled dissipation of kinetic energy in order to keep the deceleration level as least as possible. That is possible only after detailed analytical, experimental and numerical analysis of the structural crashworthiness.This paper is presenting the steps to follow in order to design specific lightweight impact attenuators. Only after having characterised the composite material to use, it is possible to model and realise simple CFRP tubular structures through mathematical formulation and explicit FE code LS-DYNA. Also, experimental dynamic tests are performed by use of a drop weight test machine.Achieving a good agreement of the results in previously mentioned analyses, follows to the design of impact attenuator with a more complex geometry, as a composite nose cone of the Formula SAE racing car. In particular, the quasi-static test is performed and reported together with numerical simulation of dynamic stroke. In order to initialize the collapse in a stable way, the design of the composite impact attenuator has been completed with a trigger which is consisted of a very simple smoothing (progressive reduction) of the wall thickness. Initial requirements were set in accordance with the 2008 Formula SAE rules and they were satisfied with the final configuration both in experimental and numerical crash analysis.     

Optimal design of composite ChamberCore structures

An optimization procedure has been developed to uniquely and efficiently determine the “best” local geometry design of a new composite ChamberCore structure. This procedure is based on minimization of the total mass of a single composite ChamberCore subject to a set of design and stress constraints. The stress constraints are obtained in closed form based on the composite box-beam model for various composite lamination designs and loading conditions. The optimization problem statement is constructed and then solved using the VMCON optimization program, which is an iterative sequential quadratic programming (SQP) technique based on Powell's algorithm. The sensitivity of the solution of the optimal geometry to the values of parameters that characterize the structural durability and the failure mechanism is discussed.     

Higher order models on the eigenfrequency analysis and optimal design of laminated composite structures

This paper deals with the structural optimization of multilaminated composite plate structures of arbitrary geometry and lay up, using single layer higher order shear deformation theory discrete models. The structural and sensitivity analysis formulation is developed for a family of C⁰ Lagrangian elements. The design sensitivities of free vibration response for objective and/or constraint functions with respect to ply angles and ply thickness are presented. The objectives of the design are the maximization of natural frequencies of specified modes and/or the minimization of the structure weight or volume. The accuracy and relative performance of the proposed discrete models are compared and discussed among developed elements and alternative models. Several test designs are optimized to show the applicability of the proposed refined discrete models.     

An expert system for finding fragility curves of building structural systems at the preliminary design stage

This research developed an expert system for determining seismic fragility curves of structural systems in a nuclear power plant or conventional building at the preliminary design stage. The resulting system simulates the performance of human experts in identifying the potential failure modes and their likelihood for a structure of interest. Induction technique is used for knowledge acquisition. The characteristics of structural systems are described by their attributes and their values.     

Multilevel assessment method for reliable design of composite structures

This work aims at demonstrating the interest of a new methodology for the design and optimization of composite materials and structures. Coupling reliability methods and homogenization techniques allow the consideration of probabilistic design variables at different scales. The main advantage of such an original micromechanics-based approach is to extend the scope of solutions for engineering composite materials to reach or to respect a given reliability level. This approach is illustrated on a civil engineering case including reinforced fiber composites. Modifications of microstructural components properties, manufacturing process, and geometry are investigated to provide new alternatives for design and guidelines for quality control.     

An application of an expert system in layout compaction of VLSI design

Abstract

Recent research in knowledge‐based expert systems of VLSI design tools has concentrated on placement, routing, and cell generation. This paper presents an alternative application for artificial intelligence (AI) techniques on compaction design for a VLSI mask layout‐expert compactor. In order to overcome the shortcomings of iterative search through a large problem space within a working memory, and therefore, to speed‐up the runtime of compaction, a set of rule‐based region query operations and knowledge‐based techniques for the plane sweep method are proposed in this system. Experimental results have explored the possibility of using expert system technology (EST) to automate the compaction process by “reasoning” out the layout design and applying sophisticated expert rules to its knowledge base.     

An expert system for hydrocarbon pyrolysis reactions

The behaviour of complex chemical reactions such as the cracking of hydrocarbons may be represented by a set of differential equations each of which corresponds to a mass balance over a single elementary species, reactant or product. The simulation of the overall reaction is achieved by numerical integration of this set of equations. For reactions such as combustion and pyrolysis of organic molecules the number of elementary reactions is very large indeed and in order to produce a viable model of the reaction it is necessary to produce a subset that approximates to the behaviour of the real system.We have developed an expert system on a VAX11/780 that generates reaction mechanisms on the basis of a generator of elementary reactions that is constrained by rules relating to initial conditions and kinetic and thermodynamic data. Chemical species are represented by PROLOG lists that can be manipulated in a variety of ways in order to generate reactions such as dissociation, abstraction, combination etc. The emphasis of the system is on eliminating unproductive reactions at an early stage in order to avoid the generation of hundreds of redundant reactions.The mechanisms generated so far for small acyclic hydrocarbons compare favourably with those produced by human experts. It appears that some relatively straightforward extensions of the existing system will result in a powerful tool for the investigation of complex reactions and the evaluation of kinetic data.     

An expert system for network management control

Abstract

Due to the varying time and the complexity of the commercial telecommunication network configuration, routing of the communication traffic becomes very important for telecommunication systems. No one can keep in mind all the complex routing plans used in networks, so it is hard to quickly take proper actions while the switching node is being blocked.

In this paper, we propose an expert system which can collect traffic data, monitor network status, reason and take appropriate actions for extreme traffic congestion on a network just as a network management expert can do. It would certainly streamline the whole network control procedure, and. provide dynamic routing functions based on the original static routing method adopted in Taiwan. It does improve both network efficiency and network reliability.     

Multiscale approach for the design of composite sandwich structures for train application

In the present work a multiscale approach is considered for the design of composite sandwich structures for a roof of railway vehicle. The procedure consists in different steps that start from cost/benefit analysis on materials and their manufacturing process and cycle up to analysis of sub-components and entire structures. Each step is characterized by experimental, theoretical and numerical studies. The design activities herein presented count experimental campaigns able to characterize both the properties of novel sandwich material, manufactured expressly for transportation industry, the sandwich and joint behaviors. Analytical and numerical approaches have been used to validate and optimize the structural layout. Finite element analysis has been also performed on a test article to verify the “new” sandwich roof in regard to structural requirements suggested by European Code.     

Nacre-inspired composite design approaches for large-scale cementitious members and structures

Nacre boasts a remarkable mechanical property profile, despite being composed 95% of a chalk-like mineral. Previous research has reported the features and deformation mechanisms responsible, inspiring many synthetic, biomimetic versions of nacre. However, due to processing challenges associated with nacre's complex structure, this composite design inspiration has not been applied on a scale useful for civil engineering applications. This research investigates the utility of nacre's composite design on a scale relevant to infrastructure by exploiting the “distributed microcracking” behavior of strain-hardening cementitious composites (SHCCs). With the goal of emulating nacre's deformation mechanisms, rather than simply structural mimicry, various design approaches within the constraints of construction practices are introduced and evaluated in direct tension and beam bending. An alternating layering scheme, using a geotextile mesh and a high strength SHCC, is seen to produce promising behavior, significantly outperforming the high strength SHCC in its monolithic form. Advantages are seen in tension, compression, and particularly flexure. The deformation mechanisms responsible for this enhanced performance, and those of alternate approaches, are discussed.     

Generalized Timoshenko modelling of composite beam structures: sensitivity analysis and optimal design

This article describes a new approach to design the cross-section layer orientations of composite laminated beam structures. The beams are modelled with realistic cross-sectional geometry and material properties instead of a simplified model. The VABS (the variational asymptotic beam section analysis) methodology is used to compute the cross-sectional model for a generalized Timoshenko model, which was embedded in the finite element solver FEAP. Optimal design is performed with respect to the layers’ orientation. The design sensitivity analysis is analytically formulated and implemented. The direct differentiation method is used to evaluate the response sensitivities with respect to the design variables. Thus, the design sensitivities of the Timoshenko stiffness computed by VABS methodology are imbedded into the modified VABS program and linked to the beam finite element solver. The modified method of feasible directions and sequential quadratic programming algorithms are used to seek the optimal continuous solution of a set of numerical examples. The buckling load associated with the twist–bend instability of cantilever composite beams, which may have several cross-section geometries, is improved in the optimization procedure.