Chapter 31 A new engineering model

At this time, Fang Zhen also returned the draft paper to Chang Haonan:

"Junior brother, can you tell me the content of the last few pages? I really can't see clearly what you wrote..."

He finally realized that he had ridiculously underestimated the other party's ability before, and he was actually planning to use some of his achievements to make a graduation project for others...

Fang Zhen was extremely glad that he did not say this out loud at the time, otherwise he would probably be even more embarrassed than Yao Mengna now - if what was written on the paper was correct, then what Chang Haonan had achieved in the three hours just this morning , bigger than the three years of his Ph.D. combined.

Everyone in the laboratory has gathered around.

"Hmm... I was in a good mood when I wrote this. It's really a bit confusing." Of course Chang Haonan didn't know what Fang Zhen was thinking, so he just took it and took a look:

"In this section, I want to linearize the wing model at the static equilibrium position and calculate the linearized mode of the wing in the trim state..."

“Assuming that the static deformation of a large aspect ratio wing under given flight conditions and self-weight is u, and the wing vibrates slightly at the static equilibrium position, the displacement of each point on the wing can be expressed as... "

“For a large aspect ratio wing model that takes geometric nonlinear factors into account, after extracting its nonlinear orthogonal modes, the motion equations of the structure can be converted to modal coordinates based on the modal superposition principle. The specific form is: The equation is marked with number 33 on the paper."

"Then rewrite it into the Laplace domain and introduce artificial damping g. By selecting a series of appropriate modes, the generalized aeroelastic equation in the frequency domain can be established..."

"..."

Although this is not a purely mathematical problem, it undoubtedly requires a deep mathematical foundation. Therefore, when Chang Haonan was halfway through speaking, everyone except Fang Zhen and Yao Mengna had already withdrawn.

Can't understand!

The two doctors who had listened to the whole story looked at each other and saw shock in each other's eyes.

They understood it and found no logical flaws in the whole process.

Therefore, the next step is to modify the program, analyze the wing flutter situation according to the theory on the draft paper, and calculate the flutter critical speed.

If the calculated results match the actual results...

That means Chang Haonan has created a new engineering model.

Although it cannot be called a complete theory, it is definitely an achievement that can leave its name in the history of the aviation industry.

It only took one morning!

"I'll do the programming!"

Although he is a relatively conservative person in character, this does not mean that Fang Zhen does not have dreams.

And if you can participate in the verification process of this model, then his name Fang Zhen may also appear in some future textbooks or manuals.

No doctor can resist such temptation.

Therefore, Fang Zhen seemed to be more anxious than Chang Haonan himself. Almost instantly, he rushed to sit down in front of the computer desk not far away and pressed the power button at the same time.

There are three public computers in the student office, but because the building has not been renovated, they can only be connected to the LAN. If you want to connect to the public network and want to check information or download something, you have to go to the computer room.

This is why Chang Haonan met Yao Mengna in the computer room on the day he was reborn.

"You don't need to change the wing modeling, right?" Fang Zhen said, opening a project file and showing Chang Haonan a look at the wing model and mesh division.

"Of course it needs to be changed. Flaps and ailerons must be modeled separately, and the previous methods of calculating the first to fifth order natural vibration shapes have also changed. The static displacement of the wing structure under the action of its own weight must first be calculated and the displacement column vector output Ug, perform a static aeroelastic analysis on the root-fixed wing model, output the static aerodynamic influence coefficient matrix Q, and then..."

"Repeat the above steps until the obtained static aerodynamic force no longer changes within the error range. At this time, the output structural node displacement array is the nonlinear static deformation of the wing model under its own weight and given flight conditions..."

At first, Fang Zhen confidently listened to the calculation process described by Chang Haonan and prepared to program the calculations, but soon he showed a confused look, and finally fell back, leaning on the backrest slightly decadently. superior.

Although I understood what Chang Haonan meant, many of the theories required for the solution steps were not directly preset in the aeroelasticity module of the MSC.NASTRAN software.

For example, the most critical step is to replace the default linear mode in the module with a linear mode.

As he had just learned the DAMP language for a short time, he really did not have the confidence to modify this module.

The opportunity to leave a name in the history of the aviation industry seems to have just passed away...

"Yao Bo, why don't you come and give it a try?"

Fang Zhen looked at Yao Mengna behind him

"I……"

It seems that the other party's situation is similar to mine.

This gave him some relief.

As for Chang Haonan... Fang Zhen no longer regards the former as a normal person.

"Forget it, I'll do it."

Chang Haonan put the last piece of scratch paper in his hand next to the computer, with the six steps of the analysis process written on it.

Fang Zhen, who was amnesty, quickly gave up his position and secretly swore in his heart that he would never be so impulsive again.

Shame on you...

Fang Zhen secretly glanced back at the other people in the office.

Fortunately, everyone was taking a lunch break or doing their own work, so no one noticed what was going on here.

Chang Haonan, who was sitting in front of the computer, had already begun the steps of reconstructing the analysis module code.

Although there is no efficiency blessing provided by the system, as a veteran in this area, his movements are still relatively smooth.

Soon, Fang Zhen and Yao Mengna moved two small benches, holding notebooks on the left and right, and sat behind Chang Haonan and started taking notes.

Yao Mengna was even a little touched in her heart - she had seen Chang Haonan's exaggerated programming efficiency in the computer room before, so she almost subconsciously thought that the other party had deliberately slowed down this time so that she, with a weak foundation, could understand.

"Although this junior may sometimes act like he doesn't deserve a beating, he is actually quite enthusiastic. He seems to be the type that is cold on the outside and hot on the inside..."

Yao Mengna was thinking this while staring at the lines of code that appeared one after another on the screen.

From the corner of her eye, she could just see Chang Haonan's side face illuminated by the CRT monitor.

"And from this angle...it seems to look pretty good."

……

When Fang Zhen's notes reached the fourth page, Chang Haonan's program was finally modified.

The next step is to modify the model and then import it for calculation.

It belongs to the field of slow work and meticulous work, and the technical content is not too high.

"Junior brother, Fang Bo and I will do the work of modifying the modeling. You can go and take a rest."

Yao Mengna noticed that Chang Haonan's face looked a little tired, so she patted his shoulder gently and said.

"Okay, I'm going to take a nap. I've finished the program. After you build the model, you can import it and try to calculate it to see if the results can come out normally."

Due to his crazy staying up late some time ago, his current biological clock is indeed a bit messed up, and it will take some time to adjust it back.