introduction
The structural design major of the Department of Aeronautics and Engineering of Northwestern Polytechnical University has been using ANSYS for undergraduate graduation design for three consecutive years. Through graduate design, undergraduates can generally master basic finite element theory and basic usage of ANSYS, laying a foundation for future study and work. Good foundation. At the same time, because of the ease of operation, diversity and strong computing power of ANSYS, students can master software operations in a relatively short period of time. The author has used ALGOR2.0, NASTRAN for Windows2.0/4.6 and ANSYS5.4/5.6 successively. For many years of teaching practice, it is felt that ANSYS is the most suitable for teaching, and it is also a commercial finite element program that enables students to come closest to the nature of finite elements. This article summarizes the main experience and experience of the author in the past few years to guide undergraduate graduation design.
1 ANSYS software operating methods
There are two main ways to operate ANSYS:
1) Graphical user interface (GUI) operation, mainly using the mouse to click on various menus.
2) APDL programming method (command input method).
A text file is created in the working directory of ANSYS. The APDL language is used to define the finite element model and calculation control parameters. Then the file is passed to ANSYS for execution. Or enter the command directly in the command input box of the ANSYS interface. For the ANSYS program system, all interface operations have corresponding command statements, but not all command statements can find corresponding menu items.
Due to the fact that undergraduate graduation design is generally tight and the task is heavy, it is generally impossible for a student to learn the two operating methods very deeply. Therefore, at the beginning of graduation design, the first step is to select the software operation method that determines ANSYS. In the specific teaching practice, generally consider the student's computer mastery, personal preferences and other factors, the instructor gives advice, the students choose their own software operating methods.
Although the students have studied one or several computer languages ​​in the second grade of the university, due to personal interests, conditions of the machine, etc., the computer level of the students at the graduation design is relatively large. For those students who are exposed to computers and have learned programming in other high-level languages ​​(such as Power Station, C++, Delphi, etc.), it is recommended that they use APDL programming as the main method and mouse menu operation as a supplement. Because the APDL language is similar to the Fortran language and is similar to other high-level languages, it is very convenient for students who are proficient in other languages ​​to get started. For students with a low level of computer, most of the language programming has been forgotten, so teachers generally recommend using GUI mode to operate ANSYS.
2. Graduation design students' learning methods and teachers' tasks
After determining the main operating methods of the students, teachers need to get started teaching ANSYS to graduate design students. According to several years of experience, the use of case teaching method in the introductory teaching can obtain better teaching results. Due to the wide range of functions and complicated operation of ANSYS, if students are allowed to learn various complicated operations during the entry stage, students will have a hard time, and case teaching methods can avoid this. The so-called “sparrows are small, fully-equipped†and simple. The case also includes the three processes of pre-processing, solving, and post-processing of the finite element. In the pre-processing, it must also include material definition, real constant definition, unit definition, and generation of grid elements and nodes, so that students can quickly grasp The finite element analysis workflow and the necessary parameters for various structural analyses.
After the introductory explanation is over, in order to cultivate students' scientific research ability, self-study ability and collaboration ability, other various ANSYS software operation learning mainly focuses on students' self-study and mutual discussion. Throughout the graduate design process, the teachers’ tasks are:
1) Begin to explain, the time is generally not more than 4 hours.
2) layout of graduation design tasks, students want to work ideas and working methods, generally do not explain the details.
3) Usually answer questions and answer questions about students' theory and operation.
4) Staged assessment of students, assessment of staged results, time progress control, and workload estimation for the next step.
5) The final review of the finite element model, the review of the calculation results, and the writing guidance for graduation design papers.
The most important task for teachers should be to use various skillful and knowledgeable methods to improve students' interest, including interest in ANSYS operations. Simply relying on the pressure of graduation design will not make students feel the joy of learning and scientific research, and there is no way to talk about subjective initiative.
Since the graduation design is different from the usual course teaching, the time for mutual discussion between the teacher and the student is relatively limited, so it is necessary to explain as much knowledge as possible in a relatively short period of time. In actual teaching, some teachers often ignore the finite element theory and focus on the software operation only, making the students aware of why they do not know why, which will also impair the students' understanding of the software. Therefore, in the teaching, we should use the finite element theory and software operation to emphasize teaching methods. Teachers can advise students to read some books and strive for students to complete similar topics and more difficult topics independently after graduation design. The theoretical self-learning ability and strong self-learning ability of software operation.
3. Examples of Case Teaching Methods (Structural Optimization Analysis)
Before the commencement of undergraduate graduation design, a considerable number of students did not come into contact with any finite element theory. However, I have learned some materials mechanics, theoretical mechanics and solid mechanics. Assumption: The graduation design topic of a student group is the structural weight optimization analysis of an aeroplane shell structure. In the entry stage of students, the following two steps are generally required to explain the case.
(1) Structural static strength analysis In this section, teachers mainly demonstrate the establishment, analysis, and post-processing of the three models.
1) The finite element model of a flat panel. As shown in Fig. 1a, the model is a solid support on the left side and a flat plate with tensile load is placed on the right side. In this example, you need to explain in order. Namely: the process of applying ANSYS to analyze the structural strength; the meaning and definition of materials, real constants, element types; the rules of the unit system in ANSYS; the establishment of solid models: point (KP)-line (LINE)-face (AREA): The method of dividing the finite element mesh; the meaning and definition of the constraint; the method of defining the load, how to distribute the uniform load to the nodes in a proportional manner: how to start the analysis; and the display of deformation maps and stress clouds in the post-processing.
2) A finite element model of a planar apertured plate. As shown in Figure 2a, the model is similar to the previous model except that a hole is made in the middle of the board. In this example, in addition to reviewing the various operations of the previous example, it is necessary to focus on the explanation. Namely: surface Boolean operations; how to obtain the ideal grid; how to understand the density of the grid is appropriate: according to the characteristics of the metal hole edge stress concentration factor equal to 3, test the accuracy of the calculation.
3) A complex space plate shell structure. From the explanation of the last two examples, students generally have mastered the initial knowledge of ANSYS, so the model needs to demonstrate a slightly more complex spatial plate and shell structure, as shown in Figure 3. At the same time, the students mainly describe how to model the process. Operation, the teacher is responsible for the overall, equivalent to the completion of a work by the students themselves with the help of the teacher. In the next step, students can completely separate themselves from teachers and complete similar tasks.
(2) Structural static strength optimization analysis The above three examples are completely static strength analysis. If the content of the undergraduate graduation design is the static strength analysis of a complex structure, the above three examples of entry education are sufficient. However, for the students who carry out structural optimization analysis, it is necessary to demonstrate the process and method of optimization analysis after a period of consolidation exercises based on the above three examples.
1) Optimization of basic theories: optimization objectives, constraints, optimization variable iteration methods (eg Newton method), etc.
2) The definition of optimization variables in ANSYS.
3) Optimize the start of the calculation.
4) Display of optimization results.
Figure 4 shows the curve of the optimization goals (total) and constraints (maximum stress) during the optimization process.
4 Conclusion
ANSYS is very suitable for undergraduate graduation design teaching. The case teaching method given in this article has been proved to be a very effective method after years of practice. The case examples given in this paper are also examples of the author's teaching practice and students are easily accepted. In the process of guiding students' learning, we must reasonably guide and fully mobilize the students' initiative according to their characteristics, basics and learning ability, so as to obtain the ideal teaching effect.
Transmission Parts is components of transmission system, transmission system is generally made up of the clutch, transmission, universal transmission device, main gearbox, differential and half shaft etc.Its basic function is the power coming from the engine to the car driving wheel, a driving force to produce, make the car can drive in a certain velocity.
For the front-engine car, the torque provided by the engine, in turn, passed to the rear wheeles from the clutch, gearbox, universal joint, drive shaft, the main reducer, differential and half shaft, so the rear wheel is known as driving wheel. When the drive wheels get the torque, it will give a backward forces on the ground, and so a forward to driving wheels of reaction, the reaction is the driving force of the car. The front wheel of the car usually don't have relationship of power with the transmission system, it is why it is called driving wheel.
Transmission Parts
Transmission Parts,Aluminum Die Casting Transmission Housing,Transmission Gears Spare Parts,Transmission Gearbox Parts
NINGBO ZHENHAI BOLANG METAL PRODUCT FACTORY , https://www.blcastings.com