Chapter 506 Just in time, a little research
It is naturally not easy for most researchers who have just begun to understand the situation of this project to interrupt in this discussion about the selection of technical routes.
Only a few people Chang Haonan originally planned to have a meeting with could participate in the discussion.
Although several old comrades worked together under the leadership of Academician Shen Hong more than ten years ago, after the die forging press project was suspended, these people were scattered to several institutes across the country for various reasons. Different research institutions located quite far apart.
Although they are still more or less continuing to study heavy-duty hydraulic presses, there is almost no academic exchange between them.
So in fact, they now know no more about each other's research content than Chang Haonan, who met for the first time but had read the materials specifically.
So, before Yan Yongnian could even think of how to speak again, another voice sounded:
"Board and frame combined structure rack, my mentor and I also used it a few years ago. I have been studying it systematically for a while.”
The speaker was a young professor from Central South University of Technology, Han Huiming.
He is only in his early 30s, so of course it is impossible for him to have participated in the research and development of the project ten years ago.
However, his mentor was one of the important experts responsible for the overall mechanical design of the rack at that time.
The old man is now too old and in poor health. He really can't make the long journey from Hunan Province to the capital for meetings, and he is unwilling to be an outsider and watch China's own heavy-duty die forging press come to fruition.
So he simply sent his most proud disciple here.
It can be regarded as a matter of resolution.
Han Huiming held a can filled with tea in his hand. After everyone's attention was focused, he continued:
"The biggest difficulty in research in this area is the lack of practical experimental methods."
"The plate and frame composite structure is faced with giant hydraulic equipment of more than 30,000 tons. Due to the amplification effect, we simply cannot It is impossible to use a scaled model to judge the stress of actual equipment, but if a 1:1 actual test is performed, it is difficult to measure the local stress of large-sized components.”
While Han Huiming bowed his head and drank. When the water was flowing, Zhang Yong, who had been listening quietly next to him, interrupted:
"If this is the case, how did other countries overcome this problem?"
Although he had already transferred I hold an administrative position, but I also majored in mechanical design in the past, so I still have some basic concepts in my mind.
In a place like the Commission of Science, Technology and Industry for National Defense, if someone with no technical knowledge at all were to be the leader, many tasks would not even be possible.
Han Huiming quickly put down the cans and bottles again and replied solemnly:
"The traditional method is to design from a theoretical level first, and then conduct actual destructive tests on the key weak parts of the whole machine. , demonstrate the feasibility of theoretical calculations, and then assemble the spare parts into large components step by step. In the process, the key large components must also be tested in the same way. This is why the French chose to purchase a finished equipment directly from the Soviet Union. It is not developed independently.”
“Our country’s foundation in this area is already very weak, and it requires a lot of time, material and financial resources. Zhongnan Industrial is not a school with strong financial resources. Our research team is in the process of allocating funds. They have no say in the matter, so... the research progress has been relatively slow.”
“However, now that Mr. Chang has enough funds and manpower, as well as the support of comrades in the weapons industry system, I feel that we are fully qualified to promote technology research and development in this direction. After all, rack modal analysis and dynamic design are not only useful here, but also have great significance for other equipment manufacturing industries in the future.”
Chang Haonan's impression of non-destructive stress testing methods mainly includes magnetic measurement and diffraction methods, but the accuracy is average and in some cases cannot even be quantified.
Although destructive stress testing is accurate and simple, it is a complete miracle of hard work.
The operation is extremely complex, and only one site can be detected at a time. If there are multiple locations on a workpiece that need to be detected, one test will destroy one sample.
In short, it’s okay to do it once or twice, but if he wants to make the entire forging press purely by this method, then he probably has hundreds of millions of funds on hand...
Not really Enough.
"What if we use numerical calculations?"
Before Chang Haonan could speak, someone mentioned what he was best at.
“We have also tried it, and even tried it some time ago using the software developed by Chang Corporation. However, it is always difficult to converge on the results after entering the calculation step, and many parts need to be modified during the modeling process. Simplified, the reference value is very limited..."
Everyone naturally looked at Chang Haonan.
“This problem does exist.”
He nodded pointedly.
Although there is no computer in front of him, Chang Haonan can now review typical problems that may arise during the simulation process even in the human brain:
"Board and frame combined model" The forging press has too many structural parts and the contact problem is too complicated. The traditional tetrahedron model composed of structured mesh often has strange stress concentration points at the nodes on the edge of the contact surface."
"If. A weak slip occurs between two objects in contact, and penetration is easy to occur. If the overall component undergoes relatively large deformation, node self-locking will occur. In short, it is normal to have problems. ”
Hearing Chang Haonan's almost unthinking judgment, most people couldn't help but have expressions of regret on their faces. After all, this seems to mean that we can only return to the traditional method just mentioned by Han Huiming.
But Han Huiming is the opposite.
Having conducted research in this area, he knew that Chang Haonan could point out the essence of the problems they faced so calmly and quickly, indicating that the latter had considered this issue before.
Definitely come prepared.
“If this is the case, the preliminary research of this project may last for a long time... Even if funding issues are not considered, destructive stress testing cannot be done quickly...”
An expert from the Northern Vehicle Research Institute who is relatively knowledgeable in this area sighed and said.
"A few years are indeed too slow, and the timetable I set cannot wait for such a long time."
Chang Haonan waved his hand, sat up straight, and faced the hundred people in front of him. Many people involved in the project said.
Not only was the weapons industry system impatient and couldn't wait too long, in fact he couldn't wait either.
According to the timetable of 601 and Sukhoi, the manufacturing process of the rear fuselage frame of the J-11A/Su-27SM will be upgraded from the current segmented manufacturing followed by welding to integrated die forging.
In addition to reducing working hours and improving production efficiency, it is also a technical preparation for the manufacturing of next-generation fighter jets and future large passenger aircraft.
It doesn’t matter that Damao already has two 75,000-ton hydraulic presses, but if the progress of China’s heavy-duty presses is hindered, it will inevitably have an impact on the localization progress of many subsequent models.
Han Huiming, who had been looking forward to it for a long time, his eyes lit up——
He knew that Chang Haonan was too busy to micromanage all the research and development work.
In this way, different people must be actually responsible for each subsystem.
The plate-frame combined structure is a research direction that he and his mentor have been adhering to over the years.
If we can continue with this configuration, on the one hand, it will be the end of the teacher's early regrets. On the other hand, for him, a newcomer who is in an unpopular major and is just starting out, it will also be a great opportunity for him. It’s almost enough to change one’s life
Not to mention anything else, just being “responsible for the main frame structural design of China’s first super-heavy die forging hydraulic press” is absolutely valuable.
“Stress testing of oversized workpieces is an engineering problem. Since the engineering problem cannot be solved, we can change our thinking.”
“From a technical point of view of numerical simulation, it will be done soon. The latest version of the TORC Multiphysics software to be released just adds unstructured overlapping grids. This definition method allows the use of hexahedral models in the model, and the model boundaries are flexible and variable, which is very suitable for calculations of multi-body relative motion and large deformation problems. ”
"On the other hand, from a more basic mathematical theory, I happen to have done some research on the direct constraint method to deal with geometric nonlinear problems."
"In this way, although it is still impossible to completely break away from the experiment, but Most of the work can be done on paper, and the accuracy and quantity requirements for stress detection will be greatly reduced!”
In fact, this is indeed a coincidence.
The reason why we were so anxious to release a new version was to solve the problems faced by Institute 601.
But just enough to eat two fish.
But to outsiders, this seems like "Mr. Chang has everything figured out."
The reincarnation of Zhuge is nothing more than this.
"Then...our technical solution is initially determined to be a panel and frame combination?"
Yan Yongnian was in charge of the overall design back then, and he had no preference for the specific route to be adopted.
As long as the die forging press can be built.
"That's right, let me assign the work tasks."
With Chang Haonan's final statement, the atmosphere in the entire small auditorium also became serious.
“Currently, since the Jiangcheng Heavy Machine Tool Factory responsible for the actual manufacturing of the forging press has not yet been officially in place, the personnel are currently divided into five research groups, which are responsible for the overall structural design; load-bearing and deformation analysis; and force flow transmission. Simulation and monitoring; pre-research of auxiliary systems such as hydraulics, sensing, and industrial control, as well as the development of supporting equipment required during the installation of the die forging press body, such as tooling trusses. ”
“Details for each team. The person in charge is..."
"..."
For Chang Haonan, this process is already familiar.
Next, it’s time to have fun again!
(End of this chapter)