Computer aided structural analysis

A tutorial survey directed to the practicing engineer who is interested in computerized techniques for static and dynamic structural analysis.The discussion is directed to the general questions which occur in the application of computer aided analysis. Consideration is given to structural modeling, input preparation procedures, solutions algorithms, numerical errors, and output interpretation. The emphasis is on large general purpose programs and on establishing a definition of the current state of the art.     

Computer aided analysis and optimisation of steam power cycles

The design of thermodynamic cycles for steam power plants is a two-stage process. The first stage consists in the analysis of several variants of a basic plant configuration suggested by previous experience, and ends up with selection of one of these variants, that which is considered to be the best by some criteria. Most designs in the past terminated thus. However, increasing energy costs and the economic impact that even a minute improvement in plant efficiency can have made it desirable to follow this stage by a second one where some kind of systematic optimisation is performed.The complexity of the cycles involved, difficulties with the complicated thermodynamic functions required for the analysis and increasing labour costs force the optimisation to be computer aided.This paper describes a method to perform computer aided analysis and design of thermodynamic cycles for steam power plants. Most of what is to be said is, however, easily generalised for other kind of cycles. The paper begins with the definition of a data structure necessary to represent plant configurations in the computer. This data structure was inspired by similar ones related to finite element and electrical network problems. The analysis of thermodynamic cycles is based, as is well known, in the balance of mass and energy laws which lead, under some common simplifying assumptions, to the set up of a linear system of equations. The solution of this system allows the computation of all the variable of interest required in order to generate a balance of mass and energy report. Then an optimisation program is described. This program performs a search for the best cycle, according to the criteria selected by the user, starting from some basic design and given constraints. Some examples representative of the program capabilities are presented.     

建筑施工模板计算机辅助设计系统

为减少建筑施工模板浪费,加快模板的施工,设计并开发模板计算机辅助设计系统.该软件是基于AutoCAD ObjectARX二次开发的,包括模板的优化配置和支撑设计,采用动态规划算法实现模板的最优布置,对模板支撑提出半刚性节点的计算模式,从模板的设计方案到最后详细的构件模板用量配置图都由计算机进行辅助设计,能够自动给出模板支撑计算书.该软件能实现模板工程中施工的数字化管理,进而规范和优化模板工程设计.     

Computer aided instruction in the skills of linguistic analysis

Students on the B.A. (honours) in Communication Studies at Sheffield City Polytechnic study linguistics as part of their degree. These students seem to vary considerably in their abilities to analyse sentences. The difficulties that they experience seem to be the same for each successive intake even though the difficulties may not be shared by many students in any particular year. Thus, the teacher of linguistic analysis often needs to resort to individual student tuition to deal with the same problems year after year. The computer aided instruction program described in this paper seeks to overcome these problems. It enables students to progress at their own rate through a series of exercises designed to instruct them in immediate constituent analysis. The program was found to be very successful in achieving its linguistic objectives and also in producing a remarkably high degree of interest in computers.     

Computer diagnosis system for thermal analysis by BEM aided with simple CAD

With the aid of the supercomputer we have performed three-dimensional simulations in practical cpu time. At the same time, though, huge amounts of output data must be treated automatically by post processors, so that only necessary information will be extracted and changes of models, mesh subdivisions, or boundary conditions will be taken into account. This type of information processing cannot be attained by conventional postprocessors, and a new concept of postprocessing and system must be developed in the sense of computer-aided engineering or computer diagnosis. We present a computer tomographic system COMTOS-BEM based on three-dimensional boundary element analysis; it houses its own geometric modeling and automatic mesh generation. Furthermore, it supports design feedback reactions to change modeling or meshing, make recalculations, and renew boundary conditions. In this paper, we state the basic concept of the proposed computer diagnosis system and present the necessary geometric modeling and processing and boundary element formulations. Some numerical examples illustrate the validity and effectiveness of our system in practice.     

Computer aided laboratory instruction

In order to give students a basic introduction to real-time applications in physics the Computer Aided Instruction Laboratory was set up at the Universität Karlsruhe. This paper describes the computer system installed and some of the on-line experiments connected.     

Computer aided part manufacturing

The decisions made by manufacturing engineers have to be flavoured by the value system of the times. The rapid change in value systems caused by the human/environmental revolution, will bring about the beginning of a new epoch in manufacturing. This will make old ways of doing things obsolete, but also create new possibilities. Therefore, manufacturing industry may change to a new pattern better adapted to the new environments.In order to meet this challenge in the Norweigan society, an industrial concept, a cell concept, has been developed by the Production Engineering Laboratory NTH-SINTEF. Vital parts of the cell concept have been tested in a full scale pilot plant, in which a variety of diesel engine parts are machined.Part programming, machine loading and scheduling in the cell together with the cell control functions, are performed computer aided, using a three level computer hierarchy.     

Computer aided setup planning for machining processes

This paper deals with an automatic setup planning system for machining processes of prismatic parts. The proposed system concurrently implements both machining sequences of reference surfaces and machining sequences of features for the purpose of minimizing number of setups in setup planning. Experienced planners' knowledge are represented as rules and used for machining sequences of reference surfaces and they are implemented by using EXSYS. A case study is performed to evaluate the performance of the proposed system.     

Computer aided reliability for optimum maintenance planning

Computer aided Maintenance planning for mechanical equipment is presented in this work to implement the optimized extensive maintenance plan at a specific time horizon. The objective is to interchange the unscheduled corrective maintenance into scheduled preventive maintenance depending on historical data of equipment. This work is concerned with development of reliability analysis based on Weibull distribution. An optimization technique has been developed to provide the optimized preventive maintenance plan for the whole equipment during a required time horizon.     

Computer aided learning and the nurse

The medium of Computer assisted learning (CAL) using a low-cost personal computer has been used to develop courseware addressing a specific teaching and learning need on the subject of intravenous drug administration. By moving away from the menu-driven format emphasis has been placed on assessing questioning rather than responses to questions. Results from formative evaluation including a pilot study have proved encouraging and provided valuable information on the modifications required.     

Computer graphics aided geometric modeling and mesh generation schemes for preprocessing and finite element analysis

The paper describes automated generation and editing schemes together with the development of computer-aided geometric models for general applications. For the construction of general finite element models of complex shapes, conventional approaches typical of wireframe, surface, or solid modeling cannot be effectively utilized for generating continuum solid models as well as discrete models simultaneously. In view of these facts, features to generate and model two-dimensional as well as threedimensional continuum and discrete models by isoparametric mapping/solid geometrical modeling techniques via a common interactive processor are described. The proposed scheme is demonstrated for modeling structural, thermal, or flow networks that are commonly encountered in engineering applications. In a research environment, the techniques addressed in this paper should prove to be very useful in providing flexibility and thereby significantly reducing the work load of frequent CAD users.     

Computer aided model building and CAL

Model building has become an educational objective at the tertiary and the secondary level. There are reservations in regard to the suitability of computer simulations for integrating modelling into the education process. Interactive simulation systems can be designed to meet educational requirements, presenting a preprogrammed simulation environment which only has to be supplied with the model itself. The model can be supplied as a set of statements (“missinglink” program) or as a block diagram representing the structure of the system. Examples are presented for both possibilities and their respective characteristics are discussed.     

Computer aided EDM electrode design

A large number of EDM electrodes are used in die and mold manufacturing. However, the electrode design is very time consuming. This paper introduces a computer-aided electrode design system for die and mold manufacturing. Using this system, when the electrode boundaries are selected, the electrode tool, its holder, and a work coordinate system are created automatically. An algorithm of sharp corner uncut detection for electrode design is also developed. With this algorithm, sharp corner uncut can be detected by calculating the surface angles at their common edges. The system has been tested and proved to be able to shorten the electrode design lead-time significantly.     

Computer aided optimal plastic design

An interactive method for optimal plastic design of structures that obey the square yield criterion is presented. Sections of fixed dimensions such as standard sections can be used for design and realistic cost estimates can be used in assessment. The design is developed interactively by upgrading in steps, using the rate of increase of strength per unit incremental cost as a guide. The entire method is explained by establishing the physical meaning of the expressions derived. The method is suitable for implementation in microcomputers.