Simulation 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 Powersim simulation program was applied to develop a computerized model of the mechanical designing structure. 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 Powersim 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.
Abstract
This paper describes an integrated computer-aided approach to the design of a gear reduction box involving modeling, simulation and automatic drawing. Powersim simulation software has been applied to develop a computer model of the mechanical structure. Special programs have been developed in order to produce two-dimensional drawings of the speed reducing assembly using AutoLisp language existing in AutoCAD . To obtain the optimal design of the parts, the results of the Powersim calculations can be transferred to Solid Worksoftware for an automatic, three-dimensional design of the selected parts using a solid modeling method. Application of FEM software allows to create an automatic mesh and perform the analysis of the stress and deformation of the part including the effects of the stress concentration. It is concluded that the method developed achieves rapid, reliable designs, useful in both industry and teaching.
Keywords: computer-aided design, modeling, simulation, gear speed reducing, gear box
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 AutoLisp 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 Powersim 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 a 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.
Summary
A comprehensive computer-assisted process of the design of a speed reducer that includes modeling, simulation and automatic drawing is described. The Powersim simulation program was applied to develop a computerized model of the mechanical designing structure. 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 Powersim 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.
Abstract
This paper describes an integrated computer-aided approach to the design of a gear reduction box involving modeling, simulation and automatic drawing. Powersim simulation software has been applied to develop a computer model of the mechanical structure. Special programs have been developed in order to produce two-dimensional drawings of the speed reducing assembly using AutoLisp language existing in AutoCAD . To obtain the optimal design of the parts, the results of the Powersim calculations can be transferred to Solid Worksoftware for an automatic, three-dimensional design of the selected parts using a solid modeling method. Application of FEM software allows to create an automatic mesh and perform the analysis of the stress and deformation of the part including the effects of the stress concentration. It is concluded that the method developed achieves rapid, reliable designs, useful in both industry and teaching.
Keywords: computer-aided design, modeling, simulation, gear speed reducing, gear box
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 AutoLisp 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 Powersim 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 a 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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