4.8 Design using computer-aided design systems
Designing objects (mechatronic modules, machines, systems) is the field
of engineering, the most difficult for automation. The theory and methods of
automation of design are under development. Well developed various computa-
tional operations associated with the design, as well as the design of text and
table documentation. But the tasks related to the creation of complex automated
systems for the preparation of production in engineering, performing, in
addition to calculations, the choice of the most rational design solutions, the
layout of machines from the components that make up them, the selection of
these elements, technological design, the issuance of project documentation in
finished form, etc., have not yet found a complete solution.
In the design process, the time spent on drawing jobs is about 30% of the
total design time, while the «creative» design elements are about 15%. Thus, in
the design process, a large proportion of the work falls on routine operations.
Therefore, the main direction of streamlining the design process is the desire
to automate routine operations with the help of computer technology.But at the
same time, the main direction in automation is not the automation of individual
design stages, but the automation of the design process of the entire design,
which must meet the initial requirements.
Automation involves the systematic use of computers in the design process
with a scientifically justified distribution of functions between the designer and
the computer and the scientifically sound choice of methods for solving the
problems of machines [12].
Scientifically grounded distribution of functions between a person and
a computer implies that a person must solve problems that are creative, and
computers – problems whose solution is amenable to algorithmization.
A system combining technical facilities, mathematical and software, the
parameters and characteristics of which are chosen with the maximum allo-
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wancefor the features of engineering design and design problems, is an
automated design system (ADS).
The purpose of computer-aided design system is improving quality, reducing
material costs, shortening the design process and elimination of growth in the
number of engineering and technical personnel engaged in the design and
construction.
To achieve the objectives of the creation of the ADS should:
• improving design on the basis of application of mathematical methods
and computer technology;
• automatization of process of search, processing and delivery of
infor-
mation;
• using of methods of optimization and contingency planning; the use
of effective mathematical models of designed objects, components and
materials;
• creation of databases containing systematized information and reference
material necessary for computer-aided design facilities;
• improving the quality of the project documentation;
• increasing the share of the creative labour of design by automating non-
creative work;
• unificate and standardization of design methods;
• training and retraining of specialists;
• interaction with automated systems of different levels and purposes.
Complex of means of automation of designing includes methodical,
linguis-
tic
, mathematical, program, technical, informational and organizational support.
In ADS provides the convenience of using programs through the use of
means of operative communication between an engineer and a computer,
special problem-oriented languages, and the availability of an information and
reference database.
The structural components of ADS are subsystems that have all the
proper-
ties
of systems and are created as independent systems.
It should be noted that ADS is an auxiliary tool, not a replacement for the
designer.
Historically, the use of a computer for design and development work in its
development has passed several stages and has undergone significant changes.
In the beginning, emphasis was placed on automating project tasks, which had
a clearly expressed design character, when manual design techniques were
implemented.Then began to create programs for automated calculations based
on the methods of computational mathematics (parametric optimization, finite
element method, etc.). With the introduction of special terminal devices, univer-
sal computer programs appeared for solving both calculated and some routine
design tasks (making drawings, specifications, text documents, etc.).
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In recent years, much attention has been paid to automation of design
and construction work in the design of mechanisms and machines, when the
synthesis of the design is heuristically performed, and the main parameters are
selected and optimized in an interactive mode of dialogue between the designer
and computer. The object is designed according to functional require-ments,
information on components and description processes using object models,
which allows the designer to specify the relationships between individual
properties as in dry your object, and between different sites within the
development.
In the model, the following set of characteristics is understood as the object
design:
• a dictionary of concepts that represent the most significant properties of
an object in the domain;
• composition and structure of the final product;
• functional requirements for separate parts of design decisions, coordina-
ted among themselves through the vocabulary of concepts by bidirectional
associative links;
• mutual arrangement of parts of design decisions within the framework
of some global coordinate system, taking into account the accumulated
rules of integration from standard solutions;
• the possibility of obtaining an informative and expressive idea of the
decisions taken both in computer form (including the possibility of three-
dimensional animation (object-animation) of the object), and in the form
of drafting and design documents;
• the ability to perform computer modeling, which ensures the control of
the ratios both between individualproperties of the object, as well as of
the whole object.
In the design of various products, the designer is forced to consider many
sources of information and be able to control the design process in time and
among staff. It is necessary to choose a software design tools and automation.
These include different versions of AutoCAD, AutoCAD Mechanical, Mecha-
nical desktop, CREDO, COMPAS-5, T-FLEX, etc.
AutoCAD – a versatile graphics system, the structure of which is based on
the principle of open architecture, allowing to adapt and develop a range of
AutoCAD functions in relation to specific tasks and requirements.
Efficiency of application of AutoCAD in the development of design docu-
mentation is provided with the following opportunities:
• availability of funds transformations: rotate/move/balancing, scaling,
constructing a mirror image, etc.;
• use ready-made snippets of drawings: the constructive and geometrical
elements, standardized designs, standard products;
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