Simulation and Modeling in the Mechanical Design of a Speed Reducer
by Derrick Corea Technosoft Innovations, IncSimulation and Modeling in Mechanical Design of a Speed
Reduction Gear Box
Summary
A comprehensive computer-assisted process of the design of a
speed reducer that includes modeling, simulation and automatic drawing is
described. The Powers simulation program was applied to develop a computerized
model of the Mechanical Designing. Special programs have been developed to
produce two-dimensional drawings of the speed reducer assembly, through the
AutoLISP language existing in AutoCAD . In order to obtain the best design of
the parts, the results of the Powers calculations can be transferred to the
Solid Works software for the three-dimensional automatic design of selected
parts, using the solid modeling method. With the application of finite element
software it is possible to create an automatic mesh and the development of an
analysis of stress and deformation of the part, including the effects of the
concentration of efforts. It is concluded that the developed method achieves
fast, reliable designs, with application in industry and teaching.
INTRODUCTION
The design of quality mechanical systems must be based on a
broad knowledge of the theory of force calculation, drawing applied to
engineering and various standards and recommendations existing in the
particular design area, as well as the designer's own experience. Currently
computers usually assist the process of creating any complex mechanical
equipment, both in the first stage of design (CAD), as in the last of
manufacturing (CAM). In the case of the design and manufacture of complex
mechanical systems, the design process should be based on a specially developed
computerized model of the mechanical structure.
This article describes a design sample of a typical
mechanical device, such as a gearbox, fully computer-assisted, but the same
procedure can be applied for analysis and optimization of all parts of each
mechanical structure.
Such a design method is based on the development of the
computerized model of the mechanical system. The structure of a gearbox is
considered a dynamic system and the model of this structure can be developed
using simulation software.
The simulation software used for modeling mechanical systems
has to meet the following requirements:
·
the model must be legible,
·
changing parameters must be easy,
·
the model must allow simulation and optimization
of the parameters,
·
the results must be presented graphically and
numerically,
·
the model allows to use only standard values,
such as number of teeth, diametral steps, materials and others, which are very
important in cases of mechanical systems design,
·
the software has to accept the graphic functions
during the calculation process that allows to use the results of the analysis
as well as the empirical recommendations,
·
the transfer of the results to other software,
such as AutoCAD, should be possible.
In this work, to develop the computer model, the known
method has been applied under the name of DINAMI-cos Systems (Forrester, 1961 ;
Wolstenholme, 1990 ; Cover, 1996 ), for which the simulation program called
Powersim 2.5b ( Powersim, 1998 ), which meets all the requirements mentioned
above. This type of model helps designers to carry out the calculations and simulations
essential to obtain an optimal design.
Likewise, this modeling program is additionally integrated
with AutoCAD which, together with Auto Lisp routines, prepares the automatic
assembly drawing in two dimensions, at any stage of the design development.
At this stage of the design development, an optimization of
the entire mechanical system is carried out in accordance with the established
optimization criteria.
The optimal design of the mechanical system parts is carried
out through the transfer of the calculations and parameters obtained from
Powers to a CAD system (in this case to Solid Works) and with this the
automatic design of parts is carried out using the solid modeling method.
This three-dimensional drawing is transferred to Finite
Elements software (such as ALGOR, NASTRAN or others) and creates an automatic
mesh to analyze real stresses and deformations, including stress concentration
effects. The optimization of the systems, as well as parts of the mechanical
structure is carried out through changes in the mechanical and geometric
parameters since the computational method presented is based on parametric
design.
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