It was Yao Mengna who asked the question.

She only felt as if she had returned to the evening when she had just met Chang Haonan, and the other party explained with a flat face why the flutter problem of flat wings could not be simulated by CFD methods.

Yao Mengna once thought that after working hard for so long, at least she would not encounter that kind of embarrassing scene again.

But apparently she still slightly overestimated herself.

When the subject extends to another field, the distance between the two seems to be abruptly widened.

"It really doesn't work the traditional way."

Chang Haonan rotated the blackboard 180° and shifted it to the other side.

In fact, even he has just clarified his mind and tried to do a bit of experimentation with the system to use the discrete element method to simulate the numerical simulation of soft abrasives.

[Based on the discrete element theory, establish a three-dimensional model of abrasive grains, set the size, shape, concentration and density of the model, consider the coupling between fluid and abrasive particles, establish contact models between abrasive grains and abrasive grains, abrasive grains and fluids, and abrasive particles and inner wall surfaces, simulate the force and motion of abrasive particles in the fluid, predict the motion law of discrete phase abrasive grains, analyze the removal mechanism of abrasive particles to workpiece materials during the polishing process of abrasive flow, and predict the polishing effect of abrasive flow......

Although the discrete element method was created in the 70s, the attention it has received so far is basically limited to the field of geotechnical engineering, and it is far less widely used than the continuous element method.

The result was a success.

[Improve the project consumption of science and technology points: 25 points, directly give the project result consumption points: 250 points, do you confirm the development of the research project: soft abrasive polishing and material surface removal mechanism based on discrete element method?] 】

This time, Chang Haonan didn't hesitate for too long, so he chose to confirm.

On the one hand, this is not his own area of expertise, and more importantly, due to the technical zeroing principle that triggered the quality problem, not only the turbojet 14B, but even the production of the turbojet 14A has been temporarily stopped, and now the 4 00 batches of J-8C ready to be delivered to the army for trial have started in the workshop of the 112 factory, and no one wants to see the scene that the finished airframe cannot be delivered because of waiting for the engine.

On the other hand, the paper in the field of control theory published in IEEE Transactions on Automatic Control directly earned him as many as 100 scientific research points and 2500 theoretical experience points, so it doesn't hurt to splurge a little bit on the use of points.

In an instant, a huge amount of knowledge and experience poured into my mind.

Even though he had such experiences many times, he was fascinated by the feeling of fullness of his body being filled.

Chang Haonan took a deep breath, raised his hand and gently supported his somewhat swollen head, and at the same time continued as if nothing had happened:

"As we all know, an important basic assumption of the finite element method or the finite volume method is that the dielectric material under study is in a continuous state."

"Under this assumption, the physical properties of materials can be expressed by continuous functions, and these functions expressing physical properties are often referred to as physical equations. Through the physical equations of the synthesized materials, the equilibrium equations of the problem, the boundary value conditions and the initial conditions, the governing equations of the problem can be obtained, so as to find the numerical solution in a specific situation. ”

"However, this type of numerical method is very problematic when dealing with bulk materials composed of large numbers of solid particles, because the individual particles in the particulate material move independently, which means that the individual element nodes are likely to undergo large deformations and displacements."

"But we can look at it from a different angle, focusing on the detailed description of the contact behavior between particle objects, between particles and boundary models, and the overall equilibrium relationship, that is, the discrete meta-thought."

"Linking the contact behavior between objects to the momentum balance equation of the system, a differential equation of motion is established for each particle element, and the equation of motion of all particles describes the overall motion of the discrete system."

"The main research process, which I currently judge, can be divided into four steps, the first is to describe the surface shape, motion and wear of the boundary model in mathematical language, and the second is to make a judgment on the contact between the particles and the complex boundary model......"

Chang Haonan talked about the basic theory for about twenty minutes, and then found that most of the people below looked at him with a clear look.

Fortunately, there are still a few relatively young engineers, and Yao Mengna is thinking seriously, and it seems that she should have understood at least part of it.

That's enough.

Similar to the situation in the 601 Institute, there are not many people who need to cooperate with him to carry out numerical simulation work, and more people still have to be responsible for specific equipment development work, that is, to really design and manufacture a grinding machine suitable for soft abrasives.

"Regarding the problem of discrete element simulation, interested comrades can come to me after the meeting to discuss in detail, I need about 3-4 people to help me with the programming and numerical analysis process."

"As for the rest of the machine design part, I think we may need to find some outside help."

After all, the main business of the 410 factory is to build aviation development rather than produce machine tools, so it's okay for them to make some technical improvements, but it is indeed a bit too difficult to build a new grinding equipment from scratch.

"It's not that hard."

Zhong Shihong, who saw the dawn of problem solving, instantly came to his senses:

"Shengjing No. 1 Machine Tool Factory and we have always been a brother unit with a cooperative relationship, they should be more experienced in this area, especially the development of abrasives and control systems have been completed by permanent workers, and the rest is the pure mechanical part."

"As for the specific way of cooperation......

Zhong Shihong lowered his head and thought for a while:

"It's just that the cooperation between the two factories is not enough, if we can really develop this equipment according to the idea of Changgong, it will be a huge encouragement and promotion for the overall development of our country's manufacturing industry, and it is the end of the year, so ......"

"My opinion is that to apply for a project urgently, it is called the 'Seiko Plan', and the goal is to systematically improve the production and manufacturing level of each manufacturing plant in our aviation industry system!"

Obviously, Zhong Shihong also has some ambitions hidden in his heart.

For him, even if the main person who completes this project can only be Chang Haonan, as the leading initiator and the position of the head of the technical department of the 410 factory, as long as it can be achieved, the benefits will definitely be indispensable.

On a larger level, if this new finishing method can be quickly promoted, it can also solve the urgent needs of many brother units.

Although the original intention of this idea is only to polish the inner wall of the air film hole, its application range is obviously very wide.

Even if only the field of aviation manufacturing is considered, there are a large number of variable diameter pipe parts, such as fuel lubrication pipelines, fuel injectors, air guide holes, etc., and the production efficiency and yield rate of each are old and difficult problems.

"Very well, then...... That's it. ”

Chang Haonan had already experienced the benefits of doing this kind of project before.

Funding and manpower are sufficient, and the various resources applied for are basically prioritized to ensure a green light all the way.

What's more, it is very generous in terms of personnel subsidies.

Even the size of Factory 182 can give a bonus of 20,000 yuan at a time, let alone Factory 410.

He doesn't think he's a materialistic person, but who wouldn't want to make more money while completing projects.

……

Of course, it is impossible to wait until the project is approved to start construction.

So the next day, before Zhong Shihong started writing the application report, several backbone forces of Shengjing No. 1 Machine Tool Factory had already come to Factory 410.

The team was led by a slightly chubby middle-aged engineer who looked to be in his forties and looked polite, named Han Youde.

After listening to Chang Haonan's complete vision of the new grinding equipment, he was slightly stunned for about a second.

Then almost subconsciously, a somewhat obscure foreign phrase was uttered.

Chang Haonan didn't understand, but in short, it wasn't English.

Fortunately, the other party quickly reacted, picked up a sharpened pencil from the table, and began to draw directly on a drawing paper.

Compared with Chang Haonan of the abstract school, Han Youde's painting skills are obviously much better, although it is a schematic diagram that is not even useful for rulers, it is still horizontal and vertical, very regular.

"Constant ......"

"Chang Haonan."

Someone just reminded me of that.

"The equipment described by Comrade Chang Haonan was brought into contact with when I was studying in East Germany more than ten years ago, and the direct translation from German is called fluid abrasive processing, or abrasive flow processing."

While Han Youde was speaking, the movements of his hands did not stop, and in a few minutes or so, the general shape of a machine jumped on the paper.

"The principle of this grinding method is not difficult, and the equipment is very simple, except for the fixture, which needs to be customized according to the parts to be machined, I can complete the design of other parts in about four to five days."

Master Chang Haonan himself heard more than one gasp-

And his own.

"So fast?"

Similar questions are usually confirmed by others to him, but now that feng shui is turning, it is his turn to ask.

The main efficiency is indeed a bit exaggerated.

"Because this abrasive flow processing method is actually not a new technology, as far as the machine itself is concerned, it is almost the simplest type, there are no high-speed rotating parts, no high-pressure parts, and there is no need for any design, even if I copy the equipment I saw in East Germany, it will not be left behind for another 20 years."

Han Youde threw the pencil on the table:

"The real difficulty of this process lies in the design of abrasive ratio and control system, such a good idea has not been widely used abroad, and there are very few people who even know about it in China, because of this."

"Because of the birth defects of soft abrasives, almost every different workpiece has to be designed, and the machine I saw in East Germany was used to process a high-pressure common rail tube, and we can see the equipment, but the abrasive formula is top secret, and it is said that it took them almost two years to find the optimal solution for that part."

"It doesn't matter, this part of the work is what regular workers are best at."

Someone next to him interjected.

"If you look at it this way, I think this craft is really dramatic."

“……”

Hearing the words of the people around him, Han Youde raised his head and glanced at Chang Haonan next to him.

But he didn't say anything, just nodded flatly:

"In any case, it is not easy to come up with this idea without seeing abrasive flow equipment before."

"Let's get to work."

……

Although the main body of the project is Factory 410 and Shengjing No. 1 Machine Tool Factory, these two obviously do not have enough conditions for Chang Haonan to do numerical simulation.

Fortunately, the current focus of the 601 side has shifted to the No. 11 project, and the computing center is mainly responsible for electronizing the design data of the Su-27 with Russian experts, and there is no large amount of work to do for the time being.

So I went around and around, and finally went back to the 601 Institute to borrow a few workstations, as well as three people, including Lin Shikuan.

Although the discrete element method is quite different from the continuous finite element method in terms of theoretical basis and calculation ideas, numerical simulation is an ever-changing thing after all, and the few people who have the foundation do not let Chang Haonan spend too much chalk and tongue, and they roughly understand the work they want to complete.

In particular, Lin Shikuan, in recent months, has made rapid progress as if he had suddenly opened his mind.

When we first met, I didn't even understand the digitization of paper materials, but now he can draw inferences about some of his own understandings.

After receiving her task, Yao Mengna did not leave immediately, but found Chang Haonan:

"Senior brother, I think this contact judgment problem only needs to conduct a neighbor search and then do an intersection test, it doesn't seem to take so long for you to arrange?"

"If it is a matter of facts, it is true, the air film hole on the vortex jet 14 is a round hole, the flow channel is very simple, the grid construction and the selection of boundary conditions are also easy, and the amount of calculation is not large."

Chang Haonan had already opened the workstation at this time, and was verifying the algorithm according to the ideas that had been written a long time ago:

"But I have some ideas for going further."

"The Han Gong in the machine tool factory was right before, soft abrasives need to be designed separately for each workpiece, which is not difficult for us to achieve, but most of the enterprise engineers have average theoretical skills, and they cannot be expected to learn the basic knowledge of discrete elements and computer programming from scratch."

"Therefore, I am going to refer to the ideas of the previous CFD to develop a relatively easy to use 3D particle discrete element simulation software, this process has great application potential, only by lowering the learning threshold, can more manufacturers benefit from it."

Hearing this answer, Yao Mengna's red lips moved slightly, but she didn't make any sound, just looked at Chang Haonan's side face in a daze.

I don't know when it started, but she likes to peek at each other from this angle.

is obviously his own junior brother, but not only is his scientific research ability stronger, but even the height at which he thinks about things is different.

"Alas......"

After a short while, Yao Mengna sighed lightly and turned to leave with a complicated expression.

(End of chapter)