Research on CAD/CAE Software of Piston Structure
The development of "Piston Computer Simulation Analysis Software" is a sub-project of the National Science and Technology Commission's research project undertaken by Shandong Piston Factory. After more than two years of hard work, it has been developed and is being put into operation in our factory with remarkable results. The software uses the UG software secondary development tool to calculate the parameters of the piston, quickly establishes the three-dimensional model of the piston assembly, converts it into a finite element analysis model, and completes the finite element analysis of the piston structure, thereby improving the quality and efficiency of the piston design and analysis. .
1 software function
"Piston computer simulation analysis software" is based on the design characteristics of piston products and the accumulation of experience of the enterprise. After systematic analysis, summarization and hard work of engineers and technicians, the company independently undertakes and designs it by itself. Firstly, the engine performance parameter data file and the typical piston design parameter data files at home and abroad are established, which lays the foundation for the piston design. Secondly, the UGIICAD/CAE/CAM software advanced features three-dimensional modeling function and excellent secondary development platform are fully utilized. The three-dimensional characteristic data model of the piston assembly is realized. Finally, the finite element analysis technology of the piston is organically integrated into the software, and the piston computer simulation analysis software of piston structure design, three-dimensional feature modeling and finite element evaluation is formed. This software is mainly composed of the following three parts:
1.1 Piston structure design
Complete the database parameter input, the calculation of the piston structure parameters, and the database management of the typical piston data entry, modification and deletion at home and abroad.
1.2 Piston group three-dimensional modeling
Firstly, referring to the design standard, the three-dimensional modeling of the piston voxel such as the piston body, pin hole, combustion chamber and ring groove is completed, and the overall three-dimensional characteristic data model of the piston is generated. Secondly, the steel plate, the iron ring, the piston pin and the connecting rod are completed. The 3D feature data model is finally acquired; finally, the 3D feature data model of the entire piston assembly is completed.
1.3 Piston finite element analysis
Complete the simplification of the analytical model, the input of material property values, the automatic division of the physical grid and the input of the load; complete the analysis and calculation of the temperature field, thermal load and mechanical load of the piston; complete the analysis of the temperature field, thermal load and mechanical load of the piston Evaluation of the results.
2 software design
The software design includes the overall design of the software, the dialogue interface design, the design of the parameter database, the structural calculation of the piston, the three-dimensional feature design of the piston assembly, and the finite element analysis and evaluation of the piston. The main work of software design is completed by GRIP and UFUN development language of UGII software. The program structure of piston structure calculation, database management, establishing 3D model and piston component assembly is quite different, and it is difficult to comprehensively describe. The module for establishing the piston voxel model is taken as an example to illustrate.
2.1 source program structure
$$Programname:piston model.grs
$$Declaration
Gripsw/declrv
String/p code(11),p name(20)
Number/resp
$$Initialize
Submdl=pistonmodelclassname
Subject=pistonmodelname
$$Createtemporaryvariables
$$Readthedefaultpointerfile
Fetch/txt,1,temp(1),iferr,halt:
Read/1,iferr,halt:,p code,p name
Fterm/txt,1,iferr,halt:
$$Closeallpartfiles
Fterm/part,all,iferr,halt:
Step1:
$$Checkwhetherthereisapiston model
Errstr=Unknownerror
Grargs/f name,f type,errstr,re code,iferr,halt:
Xspawn/ufun,ufun tmp
$$Createapistonmodel
...
...
Halt:
$$Done
Halt
2.2 Program flow chart
The program flow chart is shown in Figure 1.
3 software operation
Taking a self-designed piston as an example, the application process of the software is described as follows: start → input engine parameters → calculate piston structure parameters → three-dimensional modeling of piston voxel → generate overall model of piston → piston pin, etc. Piston assembly model→input piston group material property value→finite element meshing→applying piston load→finite element analysis calculation→finite element analysis result evaluation→end.
4 software features
According to the structural characteristics of the piston, the high-level development and application platform is selected to give full play to the comprehensive advantages of UG software, and strive to be efficient and practical. In the design, the following key technologies are mainly used:
4.1 Design Platform
HP series workstation and UGIIV11CAD/CAE/CAM software are used as the software design platform, GRIP and USER-FUNCTION language are used as secondary development tools; HP-UX10.1 Chinese version is selected to realize piston voxel naming, menu name and prompt Chinese characters Turn.
4.2 User Interface Design
The software main menu is developed with the USERTOOLS tool. The menu's graphics and Chinese characters are double-cued, concise and natural; the Chinese character hints of the piston voxel are more convenient for the designer's accurate selection and fast data entry.
4.3 Inline design
With the embedded design method, the UG function module can be directly called as a function complement and extension of the software to achieve an organic combination of specialization and flexibility.
4.4 voxel spelling
Due to the complex structure of the piston, it is not feasible to parameterize the entire piston. According to the structural characteristics of the piston, it is divided into twenty categories of components such as combustion chamber, ring groove and oil hole, called voxels; each type of component contains a variety of specific types of modules, for example, the combustion chamber includes a spherical shape, ω Shape, square, plum shape and other modules. With these piston voxels, product designers can quickly construct a specific piston as a whole.
4.5 Parameter inheritance
Utilizing the powerful assembly function provided by UG software, the piston voxels are assembled to produce the piston as a whole, so that the piston parameters can be effectively inherited.
4.6 Good scalability
Considering that in the application process, the piston voxel will continue to increase, using database technology, the increase or decrease of the piston voxel is not restricted by the software program.
5 Conclusion
The software successfully passed the project appraisal and acceptance of the National Science and Technology Commission, and was highly praised by the leaders and experts. In engine components, the piston is subjected to the most severe thermal and mechanical loads. The design of the piston will directly affect the engine's ability to achieve high performance, low emissions, low fuel consumption, and low cost. In the face of strict regulations and fierce competition, users are required to improve the quality of the piston and shorten the development time of the product. In order to adapt to this situation, the application of finite element analysis technology to simulate the working condition of the piston and predict and evaluate its performance has attracted more and more attention.
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