"So where are you now?"

Chang Haonan can't remember clearly whether the Guardian series of rocket launchers is a product made by the weapons industry or the aerospace industry, but in short, it has little to do with the aviation system.

Therefore, he has limited knowledge of the subsequent development of this model, only that it seems to have developed a fairly large model family.

Rui Xiaoting didn't answer immediately, but took the mouse and opened a file on the desktop.

It is a format that Chang Haonan is very familiar with.

Engineering files from the classical finite element analysis software ABAQUS.

It is also one of the objects that Chang Haonan benchmarked when designing his own software.

After another two minutes or so, a meshed 3D structural model was finally loaded.

"Now this is the model built when I did the finite element analysis for the Defender 1 rocket launcher, including the launch tube group, the rocket, the rotary plate, the hull and the whole gun."

Rui Xiaoting introduced to Chang Haonan while turning the page:

"On this model, limited by the level of simulation and the limitations of computer computing power at that time, in the end, only the most basic problems of launch dynamics and flight dynamics were solved."

"In the end, the Defender 1 achieved the goal of extending the range to 180km, and also won the favor of some customers who urgently need medium and long-range deterrence capabilities, but overall, this model is still far from the initial expectations."

"180km should be far away, I remember that there seems to be an international convention on the range limit of exported weapons?"

Chang Haonan is very sure that at least in the original timeline, the Guardian series is not equipped with our army for its own use.

"Yes, the range of export weapons cannot exceed 300km."

Rui Xiaoting nodded, then turned around and began to rummage through the briefcase he was carrying:

"But you're right, for the vast majority of customers, the range of the Defender 1 is actually enough, so this time we are focusing on improving other parts, mainly accuracy and efficiency when firing a salvo."

"Previously, in order to avoid the impact of vibration and tail flame on the follow-up shooting caused by the launch of large rockets, we simply referred to the design method of some ballistic missiles, and completely limited the time interval of continuous launches, but from the results, the impact of the initial disturbance on long-range ammunition is still somewhat underestimated, for example, because the rocket artillery has a directional tube, there will be a locking force in the initial stage, which acts on the position of the directional button of the missile body, which is not in the missile system......"

"Okay, I'll take a look at ......"

Chang Haonan took the mouse from the side and opened the simulated log file from the same folder.

Naturally, such a complex multi-body dynamics problem could not be calculated on such a laptop, and the other party must have also used the help of supercomputing at that time, and for a professional like him, even if he did not have any research in artillery engineering, he could still see something valuable from it.

At this time, Rui Xiaoting just took out a mobile hard disk that can be called a black technology in this era from his bag, and was about to show Chang Haonan another simulation results-

Due to the small storage capacity of a single hard drive, engineering files and simulation results cannot even be stored together.

However, after he turned around, he found that Chang Haonan had directly opened the operation log and was staring at the screen intently.

"Director Chang, I have direct results, I can't see the ...... by looking at the logs"

However, before the words fell, Chang Haonan pointed to a piece of content on the screen and spoke:

"In this precision design, the directional tube of the rocket artillery, of course, and the rocket, should be treated as a rigid-flexible coupled multi-body system, if it is simply approximated into a pure rigid body, the simulation effect will definitely be greatly reduced."

As the range and power of weapons continued to increase, so did the movement generated when ammunition was fired, and it became increasingly unfeasible to treat the various parts of the weapon system as rigid bodies as in the past, and then bring the product closer to the rigid body by increasing weight or strength, so from the sixties and seventies, elastic support and flexible body dynamics gradually developed.

That is to say, it is no longer the pursuit of absolute stability of the weapon system during the launch process (which is actually impossible), but through high-precision vibration simulation and prediction, the weapon is in the same position in the vibration waveform as much as possible every time it is launched, so that the weapon system can obtain relative consistency.

In other words, weapons and equipment designed with this idea may look like they are dangling when fired, but the actual accuracy performance is better, and the weight is much lighter.

Typical of them are the BM21 rocket launcher and the PKM universal machine gun.

Of course, Chang Haonan was able to understand this aspect, and it was also because this idea was later extended to the field of aerospace design.

In the design of Defender 1, although the evolution of the launch frame from rigid support to elastic support was considered, the barrel coupling system was still approximated into a rigid body.

It's reasonable, but it's not entirely reasonable.

Of course, this is also something that can't be helped, the design work of Guardian 1 began in the early 90s, and as Rui Xiaoting said just now, artillery equipment is not divided into too many resources, and it is already very awesome to be able to do this.

"Ah...... Yes? ”

Rui Xiaoting's hand holding the hard drive was directly frozen in mid-air.

There is nothing surprising about the conclusion itself.

This kind of problem, even the graduate students who came next to him can tell one, two, three.

In fact, this is exactly what he wanted to explain after taking out this portable hard drive.

But Chang Haonan almost didn't see any numerical calculation process, and after a few minutes of flipping through the log, he directly pointed out the problem!

Who is this?

What about "why don't we experts in the field?"

What's not as good as that?

Rui Xiaoting's reaction made Chang Haonan a little unconfident:

"Uh...... Am I not right? ”

"Yes, very much."

The former silently stuffed the portable hard drive in his hand back into his bag.

Obviously, the efficiency has improved a lot compared to the expectations before I came, but there is always a very complicated feeling, what's going on?

"Now that you've seen that, let's get straight to the point."

"In order to solve the problem you just mentioned, I have specially developed a new numerical calculation method, tentatively called the discrete time transfer matrix method for many-body systems, abbreviated as MS-DT-TMM."

"The specific idea is to linearize the dynamical equations of each element in the time domain, so that the spatial transport and time iteration aspects can be taken into account in the analysis, which is very suitable for being extended to the rigid-flexible coupling plane motion problem. Compared with the classical transfer matrix method, which can only deal with simple harmonic vibrations, the MS...... Well, my new method can analyze linear or nonlinear time-varying or time-invariant systems. ”

"However, the limitations of using this method alone are still very large, especially the elastic dynamics analysis of complex boundaries and complex shapes still relies on other numerical analysis methods, so I came here to consult with you, is it possible to jointly apply a variety of different computational mechanics methods on the same platform?"

"Of course it's possible."

Hearing this question, Chang Haonan laughed directly:

"Not only is it possible, I even have the tools."

"Grab the information and follow me."

(End of chapter)