My IQ has been increasing year by year.

Chapter 175 Materials

The air in the underground processing workshop of the School of Physics at USTC felt somewhat stuffy.

On a cast iron workbench in the corner of the workshop, there is a high-precision dial indicator.

The probe of the dial indicator is pressed firmly against the core force-bearing surface of a newly machined alloy base.

This is a beautiful work of industrial art.

The surface of the base is polished to a mirror finish by lathes and milling machines. Every chamfer and every screw hole has a seamless mechanical beauty.

Wang Dayong stood in front of the worktable, his hands supporting the edge, his sleeves rolled up to his elbows, and his forearms stained with several black oil stains.

His hair was a little messy, and he had two obvious dark circles under his eyes.

His gaze was fixed on the dial of the micrometer.

Beside them, Zhao Peng and Zheng Nan also held their breath, staring at the thin red pointer.

The central air conditioning vents on the workshop walls were blowing out wisps of warm air.

As the warm air blows, the temperature around the workbench is undergoing extremely slight changes.

"It moved."

Zheng Nan swallowed, his voice a little hoarse.

On the dial of the micrometer, the red pointer that was originally pointing to the zero mark seemed to be pushed by some unseen force.

It turned very slowly, yet with unwavering determination, to the right by half a small square.

Immediately afterwards, as the air conditioner blew in different directions, the temperature dropped slightly, and the pointer slowly moved back to the left, even past zero.

Within those few micrometers, the pointer swings back and forth like a drunken pendulum.

The accuracy has drifted again.

Zhao Peng let out a long sigh and rubbed his face.

"It still doesn't work."

Zhao Peng turned to look at Wang Dayong.

"Dayong, this is the third base you've made this week. The accuracy is still stuck at four decimal places. It just won't stabilize when it gets to the fifth decimal place."

Wang Dayong remained silent.

He slowly straightened up and walked to another table next to the worktable.

On the table lay a thick book, "Mechanics of Materials," its pages worn and frayed from repeated readings.

Beside the book was a thick stack of draft paper filled with various calculus formulas, stress tensor matrices, and deformation derivations.

Over the past three months, in order to create the perfect stress distribution base as instructed by Professor Liu, Wang Dayong, a person who gets a headache from complex mathematics, has forced himself to become a half-baked mechanical theory derivation machine.

During the day, he would work on the machine tools in the workshop, and at night, when he returned to his dormitory, he would turn on the desk lamp and study this thick textbook.

Chen Zhuo was calculating those profound and unfathomable topologies, while he was calculating the most basic yield strength and thermal stress of metals.

He calculated the force on every inch of the base according to the formula in the book.

He drew the blueprints again and again, using the smoothest transition curves to disperse the areas of stress concentration.

He believed that even if a senior professor who taught mechanical engineering at the University of Science and Technology of China were to judge it, there would be absolutely no flaws in the structure of this base.

However, in reality, it just doesn't work.

Wang Dayong stretched out his oily hand and picked up the top sheet of draft paper.

The paper contained the thermal stress deformation compensation formula that he had calculated late last night, and he had checked every number three times.

"Are our boundary conditions too idealistic?"

Zheng Nan leaned closer, looked at the formula on the draft paper, and tentatively analyzed it.

"After all, the stress conditions in reality are much more complex. How about we adjust the Poisson's ratio parameter slightly? Or run the mesh model again using finite element analysis software to see if there are any tiny stress concentrations at corners that haven't been released?"

Wang Dayong looked at the draft paper in his hand.

Suddenly, the image of Chen Zhuo looking relaxed and carefree in the dormitory flashed through my mind.

What others calculate with their brains can fit perfectly into reality.

What Wang Dayong calculated stroke by stroke according to the book turned out to be nothing more than a pile of unruly scrap metal in reality.

An unprecedented sense of frustration surged from his chest to his head.

Wang Dayong slowly crumpled the draft paper into a ball.

He walked to the workbench, glanced at the dial indicator that was still swaying from side to side, and then glanced at the thick book "Mechanics of Materials".

He suddenly reached out and grabbed the book.

Relying on his memory, Wang Dayong quickly flipped through the pages, finally stopping at a chapter near the middle.

The chapter title is:

Thermal strain and thermal expansion of materials.

Wang Dayong stared at the most basic formula on the page.

The amount of deformation is equal to the coefficient of thermal expansion multiplied by the original length, and then multiplied by the temperature difference.

It's such a simple multiplication formula.

There is no complicated calculus, and no dizzying tensor matrices.

Wang Dayong stared at the Greek letter.

The boldface text on the pages is written very clearly.

When the temperature of any solid material increases, the thermal motion of its internal molecules or atoms intensifies, leading to an increase in the average distance between atoms, which manifests as an expansion of macroscopic volume.

This is an inherent physical property of materials.

Wang Dayong's eyes slowly narrowed.

All the jumbled stress formulas, geometric chamfers, and structural optimizations in his mind vanished in that instant, as if swept away by a strong wind.

"Snapped!"

Wang Dayong slammed the thick book "Mechanics of Materials" shut and slammed it heavily on the table.

The sound startled Zhao Peng and Zheng Nan in the quiet workshop.

"Dayong, what are you doing? Where did you miscalculate?"

Zhao Peng quickly asked.

Wang Dayong turned around.

His face, which usually carried a hint of naivety, was now devoid of self-doubt, replaced only by an almost savage, clenched-teeth expression.

"It wasn't a miscalculation."

Wang Dayong pointed to the book "Mechanics of Materials" on the table, and then to the crumpled draft paper.

"What's the point of calculating that!"

Zhao Peng and Zheng Nan were both stunned.

Wang Dayong strode to the worktable, ripped off the dial indicator mounted on the alloy base, and tossed it aside.

"Senior brother."

Wang Dayong turned his head and looked at the two doctoral students who were intimidated by his demeanor.

He stretched out his finger and tapped it heavily on the perfectly polished alloy base.

"You're still wondering if the shape wasn't designed well, or if the stress-bearing surfaces weren't spread out properly."

Wang Dayong's voice echoed in the workshop.

"It's not about shape at all! It's clearly written in the book that if it's just ordinary iron or steel, and the room temperature changes by even a fraction of a degree, the atoms inside will start to scramble outwards!"

He grabbed a handful of air and made an outward expansion motion.

"No matter how beautifully you calculate calculus, no matter how fancy your calculations are, can you stop this piece of iron from heating up and expanding on its own?"

'

"cannot!"

Wang Dayong gave his answer decisively.

"We've gone to great lengths to perfect the mechanical structure, even distributing the force to the smallest strand of hair, but that's the nature of this material. It's something that can breathe and expand and contract with temperature; the mechanical structure can't control the temperament of its atoms."

Wang Dayong looked at the base.

"It's not that our skills are lacking, it's a problem with the materials themselves."

The workshop fell silent.

Zhao Peng and Zheng Nan exchanged a glance.

As doctoral students in theoretical physics, they certainly know the principle of thermal expansion.

However, they are more accustomed to using algorithms on computers to compensate for these errors, and rarely do they, like Wang Dayong, directly dissect the theory and return to the most basic physical common sense.

"You make a good point."

Zhao Peng nodded, his brows still furrowed.

"Ordinary metal materials do have a limit to thermal expansion. If the structure can no longer be optimized, then we can only try to find a solution from the material itself."

Zhao Peng looked at Wang Dayong.

"To solve this problem, we need to change the material. In industry, the base of high-precision measuring equipment is usually made of a low-expansion alloy called Invar, which contains a large amount of nickel. Its coefficient of thermal expansion is one-tenth or even less than that of ordinary steel."

"Then let's go buy it," Wang Dayong immediately replied.

Zheng Nan gave a wry smile.

"It's not that easy."

Zheng Nan pulled up a chair and sat down.

"For special materials like Yingang steel, there are very few readily available retail bars or plates on the market. They have to be ordered from specialized special steel plants. Not to mention how long the approval process for laboratory funding takes, the delivery time from the manufacturer alone will take at least half a month."

Zheng Nan pointed to the calendar on the wall.

"The teacher said that the core components of the wind tunnel will be tested next Monday. We simply can't wait another two weeks."

No money, no time.

The theoretical path has reached a dead end, and we can't buy high-end materials.

Zhao Peng scratched his head in frustration, pacing back and forth in front of his workbench.

"This won't work, that won't work either. We can't exactly put the entire lab inside a constant temperature chamber to do the measurements, can we? With the air conditioning on and off, the precision to the last five decimal places is completely compromised."

Wang Dayong stood there, head down, looking at his hands.

Since high-end materials are unavailable.

Since physical laws dictate that metals must expand when heated.

Then let's go along with its temperament.

Even Yu the Great, who was controlling the floods, knew that dredging was better than blocking.

Should we prevent metal from expanding if it's meant to?

On what grounds?

Suddenly, a scene popped into Wang Dayong's mind: he remembered watching an old watch repairman fix those old-fashioned clocks in the village.

The pendulum of those old-fashioned grandfather clocks is not made of a solid piece of wood or iron to prevent it from running slowly due to thermal expansion in summer and running fast due to thermal contraction in winter.

It is made of several thin rods of different metals, which are spliced ​​together in an interlocking manner.

Some grow upwards, some grow downwards.

Wang Dayong suddenly raised his head.

Without saying a word, he turned around and walked towards the storage room at the very back of the workshop.

"Dayong, where are you going?" Zhao Peng called out from behind.

Wang Dayong did not reply.

The storage room was dimly lit, and the floor was piled with all sorts of old and broken machine parts, broken cutting tools, and scraps left over from students' experiments.

Wang Dayong stepped on a pile of scrap iron sheets and rummaged through a jumble of metal rods.

A few minutes later, Wang Dayong pulled out two dusty metal rods from inside.

One of them is a steel pipe whose surface has become somewhat dark.

The other one is a solid aluminum rod that is noticeably lighter in the hand.

Wang Dayong casually wiped the dust off the aluminum rod with his hand and glanced at it in the light from outside the door.

"Okay, it works."

He carried a steel pipe and an aluminum rod and strode back to the worktable.

Zhao Peng and Zheng Nan stared blankly at the two metal rods in his hands, which looked like they had been picked up while scavenging.

"Dayong, what are you going to do with this? This piece of junk steel pipe hasn't even been surface-treated, and the aluminum rod is too weak to be used as a base support."

Zhao Peng quickly tried to dissuade him.

Wang Dayong threw the two metal rods onto the worktable.

It made a crisp sound.

"If they can't provide support, let them do something else."

Wang Dayong walked to the tool cabinet next to him, opened the cabinet door, and took out a vernier caliper, a steel ruler, and several files of different sizes.

He didn't even open that book, "Mechanics of Materials".

He picked up a black marker and drew several lines on the steel pipe and aluminum rod respectively.

"Senior brother."

Wang Dayong drew the lines while speaking without looking up.

"If we can't buy Yinggang, then we won't. Don't aluminum and steel tend to expand? Today I'll let them expand to their heart's content."

Zhao Peng and Zheng Nan couldn't understand what Wang Dayong was saying at all.

But in the next few hours, they witnessed what true, beast-like mechanical intuition was like.

Wang Dayong did not open any CAD drawing software.

He didn't even draw a single sketch.

All those complex dimensional relationships and tolerances were rapidly spinning and combining in his brain, which knew absolutely nothing about calculus, in the most primitive and intuitive three-dimensional way.

The roar of lathes filled the workshop again.

Wang Dayong skillfully secured the steel pipe in the three-jaw chuck and pulled down the safety cover.

The lathe tool cut into the steel pipe, splashing a series of red sparks. Pale blue cutting fluid sprayed onto the blade, instantly turning into white smoke that rose up, bringing a pungent burnt smell.

Wang Dayong's gaze was frighteningly focused.

He turned the lathe's feed handwheel entirely by feel, and the cutting thickness and feed speed relied entirely on his instinct to listen to the sound and observe the shape of the metal chips.

After cutting the steel pipe, he switched to the aluminum rod.

Aluminum is soft, so it doesn't make as loud a sound when machining, but it's more likely to stick to the cutting tool.

Wang Dayong's movements became much lighter, and the aluminum shavings produced by the machine were like silvery-white springs, falling down the tool holder into the collection tank.

No one spoke in the workshop all afternoon.

The only sounds were the roar of the machine tools and the buzzing of metal being cut.

It was evening.

The machine tool finally stopped.

Wang Dayong used an air gun to blow away the debris from the parts.

What's placed on the worktable is no longer a steel pipe and an aluminum rod.

The steel pipe was cut into a specific length, hollowed out in the middle, and precision internal threads were machined at both ends.

The aluminum rod was also cut in half, and its diameter was machined just enough to fit inside the steel pipe. External threads were machined into its bottom, and its top was machined into a connecting flange with a small protrusion.

Wang Dayong picked up the parts and walked to the welding workbench next to him.

He put on the black welding mask that was covered in scratches.

Pick up the welding torch.

Sizzle~

A blinding arc of light shone in the corner of the workshop.

The flying welding slag landed on the cement slab on the ground, dancing and then extinguishing.

He inserted the aluminum rod into the steel pipe, but he didn't weld both ends shut during the welding process.

He created a structure that Zhao Peng and Zheng Nan couldn't understand at all.

He welded the bottom of the steel pipe to a base used to fix it to the ground.

Then, he welded the top of the aluminum rod that was inserted inside to the top of the steel pipe tightly together.

The aluminum rod is suspended inside the steel pipe.

Finally, he welded the load-bearing flange, which was actually used to support the dial indicator and testing equipment, to the bottom of the suspended aluminum rod inside.

This is a very strange, even somewhat ugly, nested structure.

It completely contradicts the aesthetic standards in textbooks that emphasize one-piece molding and uniform stress distribution.

It looks like a hastily cobbled-together piece of junk.

"Done."

Wang Dayong turned off the welding machine, took off his mask, and wiped the sweat from his forehead.

He used a hammer to knock off the slag on the surface of the weld, revealing the rough but solid metal fusion surface inside.

Zhao Peng stepped forward, looked at the strange metal lump, and frowned even more.

"Dayong, what exactly are you welding? How come the load-bearing surface is under the suspended aluminum rod inside? This structure completely defies the common sense of statics."

Wang Dayong didn't rush to explain.

He moved the newly welded, still slightly warm, nested base onto the dial indicator's test bench.

Secure it firmly with bolts.

Then, he placed the dial indicator probe back against the side of the load-bearing flange at the bottom of the aluminum rod.

"You'll know once you try it."

Wang Dayong turned to look at Zhao Peng.

"Senior brother, bring that industrial heat gun over there."

Zhao Peng paused for a moment, then glanced at the industrial hot air gun in the corner that was used for high-temperature aging tests.

"Use a heat gun? Those things blow out winds of several hundred degrees Celsius. This is a precision test; aren't you just messing around?"

"Bring it here."

Wang Dayong's voice wasn't loud, but it carried an undeniable confidence.

Zheng Nan gritted his teeth, walked over, plugged in the heat gun, and dragged the long power cord over.

"blow."

Wang Dayong pointed to the steel pipe of the nested base.

Zheng Nan glanced at Zhao Peng, and seeing that Zhao Peng did not object, he pressed the switch on the heat gun.

A wave of intense heat surged forth instantly.

Visible distortion of the air was created around that ugly base.

The temperature of the steel pipe on the outer layer of the base began to rise sharply, and the originally dark gray metal surface even showed a slight yellowish-blue oxide layer due to the high temperature.

Zhao Peng and Zheng Nan both fixed their gazes on the dial of the dial indicator.

When hot air at several hundred degrees Celsius blows directly on you, the effect of thermal expansion will be amplified countless times.

Logically speaking, even if the base is very sturdy, the hand should have already struck the full dial and deflected to who knows where.

The pointer trembled slightly in the first second. That was the release of surface stress generated when the base shell was first heated.

Zhao Peng's heart was in his throat.

The second second.

The third second.

Time passed by, second by second.

The heat gun has been blowing continuously for a full minute.

The steel pipes on the outside of the base were so hot that they were impossible to touch with your hands.

but.

A miracle happened.

The red pointer on the dial of the micrometer.

After an initial slight tremor, it seemed to be completely welded to the dial.

It remained steadily at a tiny position to the right of the zero mark, firmly stuck at the precision of five decimal places.

No matter how Zheng Nan changed the angle of the hot air gun, no matter how rapidly the surrounding temperature rose.

The pointer remained completely still.

As stable as Mount Tai.

The only sound left in the workshop was the whooshing of the heat guns.

Zhao Peng slowly opened his mouth wide.

Zheng Nan's hand holding the heat gun froze, and he forgot to turn it off.

"This—how is this possible?"

Zhao Peng suddenly took a step forward, almost pressing his face against the glass cover of the dial indicator.

He couldn't believe his eyes.

He turned his head and looked at Wang Dayong, who was covered in sweat and whose clothes still smelled of burnt welding. His voice even changed.

"You didn't even write out the differential equations! You didn't even calculate the compensation matrix for the thermal expansion coefficients! How could you possibly cancel out the shrinkage ratios of these two metals so perfectly by hand-cutting them?!"

This is like someone firing a shot without a scope, and it happens to hit a fly 800 meters away.

In the eyes of academics, this is simply trampling on the dignity of physics.

Wang Dayong looked at his two dumbfounded senior brothers.

He walked over and reached out to turn off the heat gun in Zheng Nan's hand.

The workshop returned to silence.

Wang Dayong grabbed the towel hanging around his neck, wiped the sweat off his face haphazardly, and grinned, revealing a bright and simple smile.

"Why bother setting up equations, senior?"

Wang Dayong walked to the still-hot base, stretched out his two hands, and gestured in the air.

"The book says that aluminum expands quickly, while steel expands slowly."

Wang Dayong pointed to the outer layer of steel pipes.

"I welded the bottom of this steel pipe to the outside. When I blow hot air on it, it expands due to the heat, so won't it grow upwards?"

Zhao Peng nodded subconsciously.

"As it grows upwards, the aluminum rod welded to the top also rises along with it."

Wang Dayong made an upward lifting motion with his hand.

Then, he pointed with his other finger to the aluminum rod hidden inside.

"but!"

"The aluminum rod is inside, and it gets heated too. Aluminum is more volatile than steel; it expands faster than steel, and once it expands, it stretches downwards."

Wang Dayong placed both hands on his chest.

The right hand represents the upward pulling force on the steel pipe, and the left hand represents the downward elongation force on the aluminum rod.

They clenched their hands together abruptly, making a wrestling motion.

"When I cut that aluminum rod, I measured it with a ruler. The coefficient of thermal expansion of aluminum is about twice that of steel. So, I only need to cut the length of the inner aluminum rod to half the length of the outer steel pipe."

Wang Dayong looked at Zhao Peng and Zheng Nan, and used the simplest, most straightforward language to reveal a marvelous mechanical and physical mechanism.

"The outer steel pipe extended upwards by one millimeter. The inner aluminum rod extended downwards by exactly one millimeter."

"One pulls back, the other pushes outward."

"As long as these two materials counteract each other and cancel each other out, the internal stress will close itself off."

Wang Dayong pointed to the flange at the bottom of the aluminum rod that connects to the dial indicator probe.

"So, no matter how much they swell up inside, or how fiercely they fight, the bottommost load-bearing outer frame connection point is firmly locked in place by these two forces."

"They can swell however they want inside, but they can't move even a micrometer outside!"

As Wang Dayong finished speaking...

Zhao Peng and Zheng Nan stood there for a long time, looking at the ugly, rough, but reliable nested base.

With a pure, savage, irrational physical intuition.

There are no complicated mathematical derivations, and no expensive special materials.

Using two broken pipes salvaged from a scrap heap, Wang Dayong painstakingly pieced together a "perfect" non-expanding structure in the real physical world through the most primitive cutting and welding techniques.

Zhao Peng took a deep breath.

"Da Yong".

Zhao Peng's voice was filled with genuine amazement.

"You little rascal, no wonder you're in the gifted youth program, how are your brains structured?"

Wang Dayong scratched his head sheepishly, looking a little embarrassed.

"What do you mean by how it's done? I just get a headache looking at those formulas. I can't figure them out. If I can't figure them out, I have no choice but to just start doing it myself."

He turned his head and looked at the base, which had begun to cool down slowly.

Although he managed to get through the current problem today by using a makeshift method of arguing between two materials.

But this was the first time he had felt it so clearly.

Nested mechanical structures are ultimately just opportunistic tricks.

Today we can use two pipes to counteract thermal expansion, but what if we encounter temperatures of several thousand degrees tomorrow? Or what if we encounter tens of thousands of tons of hydraulic pressure?

Back then, it was useless to fight each other with a few pipes.

What truly determines the life or death limit of an industrial piece of equipment is not how beautiful the blueprints are.

It's not the metal itself, but the metal itself.

Material.

Wang Dayong looked at the base, his eyes gleaming with an even stronger desire.

If one day I can stop collecting scrap materials to piece things together.

How awesome would it be if one day I could personally forge a piece of iron in a furnace that would never expand and would never break no matter how much it was shaken?

This idea ignited in Wang Dayong's mind like a spark.

"Let's go, senior brother."

Wang Dayong dusted off his hands and glanced at the clock on the wall.

"It's lunchtime. Let's leave this base here to air out for a while. We'll show it to Teacher Liu tomorrow morning. Let's go to the cafeteria to reserve seats first, or the stewed ribs will be gone."

The two couldn't help but exchange a glance.

"Walk!"

Zhao Peng waved his hand.

"This rib meal is on me today! Da Yong, eat whatever you like!"

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