The science of friction -- and its surprising impact on our lives | Jennifer Vail

Transcriber: Joseph Geni Reviewer: Camille Martínez

翻译人员: Isabel Z 校对人员: Yanyan Hong

I have to admit that it's a lot of fun

当人们问我做什么工作时，

我得承认答案很有趣。

when people ask me what I do for my job,

因为我告诉他们， 我就是拿物品相互摩擦。

because I tell them I literally rub things together.

This sounds ridiculous,

只是拿东西相互摩擦，

just rubbing things together.

听起来很荒唐。

But it has a technical name:

但是它有一个技术别称：

tribology.

摩擦学。

T-r-i-b-o-l-o-g-y,

T-r-i-b-o-l-o-g-y，

from the ancient Greek word "tribos,"

源自古希腊语：“tribos”，

which means "to rub."

意思是“摩擦”。

It's a funny-sounding word you've probably never heard before,

你可能从来没听过 这个有些好笑的词，

but I promise you,

但是我向你保证，

discovering it changes your experience with the physical world.

探索它，将会改变 你对物质世界的体验。

Tribology has given me amazing projects.

摩擦学给了我机会去 从事许多很棒的项目。

I've worked on materials that fly, and I've worked on dog food --

我研究过飞行器材料， 也研究过狗粮——

a combination that doesn't sound like one person has any business doing

除非你开始以摩擦学的 眼光来看这个世界，

in the span of just a couple years,

不然这组合

until you start to view the world through a tribological lens.

一般人很难 在几年内同时接触到。

And I think you'll be surprised

我想你们会惊讶于

at how significant a little bit of tribology can be

一点摩擦学在解决难题上的

in alleviating some very large problems.

重要性。

Tribology is the study of friction, wear and lubrication.

摩擦学是研究摩擦力、 磨损和润滑的学科。

You have all experienced all three of these things.

你们都体验过这三个东西。

Remember the last time you tried to move a heavy object across the floor,

还记得上一次你试着 在地板上移动重物的时候，

你能够感觉到 有东西在阻止你吗？

and you could just feel something resisting you?

That would be friction.

那就是摩擦力。

Friction is the force that opposes motion.

摩擦力是阻碍运动的力。

Wear is the loss or transfer of material.

磨损则是指物质的损耗和转移。

It's the reason you have to replace your favorite shoes,

再喜欢的鞋子，鞋底终究

because eventually the soles disappear.

会因磨损殆尽而被淘汰。

Lubricants are used to reduce friction and wear.

润滑剂能用来减少摩擦和磨损。

They loosen up those stubborn rusted bolts that just otherwise will not budge.

它们能松开那些生锈卡死， 难以转动的螺栓，

But tribology is also defined as the science of interacting surfaces

但是摩擦学也被定义为 在相对运动中，

in relative motion.

表面相互作用的学科。

So, interacting surfaces in relative motion:

所以，相对运动中的表面相互作用：

there are a lot of those in the world.

世界上有很多这样的例子。

As you're sitting there right now, are you wiggling your foot at all

你现在坐在这里，

是不是在活动你的双脚， 或者不断改变你的坐姿。

or maybe shifting around in your seat?

因为摩擦学正在起作用。

Because guess what? Tribology is happening.

Even the smallest shift in your seat

即使你只是在椅子上稍稍挪动，

involves two surfaces moving relative to each other.

都涉及了两个相对运动的表面。

And your tribological interaction for the shift

并且你移动的摩擦作用

will be different than the person next to you.

会与你身边的人有所不同。

This is because the clothes you're wearing

这是因为你所穿的衣服

change the friction between you and the seat.

改变了你和座椅之间的摩擦力。

If you're wearing silk, it's a little easier to squirm around in the seat

如果你穿了丝绸，会比你穿羊毛时

在座位上扭动更容易一些。

than if you're wearing wool.

这是因为丝绸的摩擦力小一些。

That's because the friction is lower for silk.

If you're moving your ankle or wiggling your ankle at all,

你在移动或者扭动脚踝的时候，

did it make a popping sound?

是不是有发出“咔咔”声？

You've had that, right?

你经历过的，对吧？

You get up, you move around, and some joint cracks or pops.

你起床，走动， 一些关节碰撞发声，

这都是因为摩擦学。

Thank you for that sound, tribology.

That sound can come from the fluid that lubricates your joints

这种声音可能是由于 润滑关节的

just moving around.

液体中的气泡

被释放所导致的。

You're essentially releasing gas bubbles in that fluid.

That sound can also come from the tendons simply moving over each other.

这种声音也可以来自于 肌腱之间的相互移动，

Pretty common in the ankle,

在脚踝处很常见，

so any of my fellow foot-wigglers out there

所以我那些喜欢 扭动脚踝的朋友，

may suddenly find themselves curious about the tribology of tendons.

会突然对肌腱之间的 摩擦学感到好奇。

But how does one become a tribologist like me?

但我又是如何成为摩擦学家的呢？

It starts when you're a kid, of course.

当然，这得从小时候说起。

I was a ballerina growing up.

我跳着芭蕾舞长大。

I reached the level where I was dancing on my toes,

我可以踮着脚尖起舞，

or "en pointe."

法语里叫 “足尖舞 (en pointe)”。

Now, when you're dancing en pointe, you're wearing those amazing shoes,

当你踮着脚尖跳舞时， 你会穿着那漂亮的舞鞋，

but they can be slippery on the stage.

但是它们可能会 让你在舞台上打滑。

The last thing you want to do when you're trying to dance on your toes

当你跳舞的时候，最可怕的

莫过于滑倒。

is to slip and fall.

So we had boxes of stuff called rosin.

所以我们会用一种叫松香的东西。

We would step into the rosin, put a light coating on our shoes.

我们踩进松香里， 舞鞋上就会有一层薄膜。

Rosin comes from tree sap

松香来自于树液，

and, in its powdered form, makes things less slippery.

粉末状的松香可以防滑。

You learned real fast as a dancer

作为一个舞者，你会很快知道

how much was the right amount to put on your shoes,

应该放多少松香在舞鞋上。

因为如果没有放够， 你很可能滑倒，

because if you didn't put enough on, you were probably going to slip

因为你的鞋子和舞台之间 没有足够的摩擦力。

due to the low friction between your shoe and the stage.

Best case scenario,

幸运的话，

you're the clumsy ballerina on stage,

你只是在舞台上 看起来手脚不协调，

but the worst case scenario would be an injury.

但要是运气不好，你就会受伤。

Already, I was optimizing and manipulating friction.

那个时候，我已经在 优化和控制摩擦力了。

You see, I was destined to be a tribologist.

你们看，我注定 要成为一个摩擦学家。

(Laughter)

（笑声）

But you were also a junior tribologist.

但是你们也是 初级的摩擦学家：

When you used crayons or colored pencils,

当你使用蜡笔和彩铅的时候，

you knew that the harder you pressed, the darker the color.

你知道你用的力气越大， 颜色就会越深。

You also knew this meant you were going to have to sharpen

你也知道这意味着

你要更加频繁地削笔，

that crayon or colored pencil more frequently,

因为它们会更快地磨光。

because it was wearing down faster.

Now let's talk about those enticing shiny waxed floors

现在让我们来谈谈 那些闪亮的打蜡地板，

that you just had to slide across.

人人都想在上面滑来滑去。

You knew if you put on a pair of socks,

大家都知道如果穿双袜子，

you were going to get a really good slide across that floor.

滑动起来更加容易。

赤脚可就没那么轻松了。

Good luck trying to do that barefoot.

Master manipulators of friction.

多么高明的摩擦力操纵技巧。

All kids are tribologists.

孩子们都是摩擦学家。

What about us as adults?

那么大人呢？

At some point today, you brushed your teeth.

各位今天都刷过牙了，

I hope.

但愿如此。

(Laughter)

（笑声）

This is tribology in action.

这就是摩擦学的作用。

The toothpaste and toothbrush are working to remove or wear

牙膏和牙刷的作用 是清除或磨掉

the plaque from your teeth.

你牙齿上的污渍。

For the record, my dad is a dentist.

郑重声明，我爸爸是牙医。

Never thought my career was going to circle back to the family business.

我从来没有想过 自己会追随他的脚步。

But one day, we found ourselves speaking the same language

但是有一天我们发现 我们说着相同的话，

当时我刚接受了 开发牙渍去除测试的任务。

when I was tasked with developing a test to investigate plaque removal.

Sounded simple enough,

听起来很简单，

until I started to look at it as a tribologist,

直到我开始 以摩擦学家的角度看待它，

and then it became incredibly complex.

才发现它非常复杂。

You have hard materials -- those would be your teeth --

其中涉及到坚硬的材料—— 这就是你的牙齿；

soft materials like your gums, the toothpaste, the toothbrush.

软的材料—— 就像你的牙龈，牙膏和牙刷；

There's lubrication -- the form of saliva and water --

润滑物——像是唾液和清水；

the dynamics of the person doing the brushing and more.

还有人们刷牙的动作，等等。

I promise if we put diamonds in your toothpaste,

我保证如果我们在你的 牙膏里添加钻石，

you're going to remove that plaque.

牙渍便可以去除，

Probably going to remove your teeth as well.

很可能还会连你的牙齿一起磨掉。

So there's a fine balance to be had between wearing the plaque away

所以需要一个去掉牙斑 又不伤害牙齿牙龈的

and not damaging your teeth and gums.

折衷方法。

We're brushing our teeth because we ate.

我们刷牙是因为我们要吃东西。

Eating is another routine thing we all do.

吃东西是我们另一个日常所需，

Seems simple enough.

看起来很简单，

But it's another field of tribology,

但它是摩擦学的另一个领域，

and it's not so simple.

并没有那么容易。

You have the food, which will break and wear while you're eating,

你吃东西的时候， 食物会被破坏和分解。

这些食物和你的牙齿， 舌头，唾液和喉咙

and that food is interacting with your teeth, your tongue,

your saliva, your throat.

相互作用。

And all of those interactions are going to influence your experience of eating.

所有的这些作用都会 影响你的进食体验。

I think you can all recall a moment where you tried something new

我想你们都会想起 尝试新事物的时刻，

and you just found yourself going,

你会发现自己在想：

（咀嚼声） “味道还行，

"Well, it tastes alright.

I really don't like that texture."

但我真的不喜欢这种口感。”

Tribologists are looking at lubricity, the coefficient of friction,

摩擦学家研究润滑和摩擦系数，

as ways to connect mouth feel and texture to what you're experiencing,

让你体验到的口感 和味道得以相辅相成，

so that if we're changing the formulations of what we're eating and drinking

所以当我们改变饮食配方，

不同的糖分含量或者脂肪含量，

so the sugar content or fat content are different,

how does that change mouth feel?

口感会出现怎样的变化？

How do we quantify that?

我们将如何量化这个问题？

This is what tribologists are looking to solve.

这就是摩擦学家要解决的问题。

And while my colleagues were in one corner of this lab

当我的同事 在实验室的一个角落

looking at the fat content of yogurt,

研究酸奶的糖分含量，

I was in another corner

我在另外一个角落

studying dog food.

研究狗粮。

That lab smelled really good, by the way, let me tell you.

顺便说一句， 那个实验室闻起来很香。

We all brush our teeth on a regular basis.

我们都会有规律地刷牙，

How many of us brush our pets' teeth?

但有几个人会给宠物刷牙？

Animals as adults commonly get periodontal disease,

成年动物通常会患牙周病，

so we really should be brushing their teeth,

所以我们应该给它们刷牙。

越来越多的宠物主人 开始这样做了。

and more pet owners are starting to do this.

我知道我的好朋友 很擅长给她的猫咪刷牙。

I know my best friend is really great at brushing her cat's teeth, somehow.

Good luck trying to do that with my cat.

我希望我也能这样。

So what pet food suppliers are trying to do

宠物食品供应商正在尝试

is incorporate plaque removal in things like treats.

研发能够去除牙斑的零食。

If you have a dog,

如果你有养狗，

you may have observed that you give a dog a treat,

你会发现喂狗吃零食，

and it magically seems to disappear after just one bite.

它一口就能吞下去，很神奇。

So the added challenge here is:

所以更大的挑战在于：

How do you remove plaque when you have one bite?

如何在一口吃掉大餐的 情况下去除牙渍。

I developed a benchtop test to study this problem,

我开发了一个台式实验 来研究这个问题，

and to do so, I had to mimic the oral system of dogs:

还模拟了狗的口腔：

their teeth, plaque, saliva.

包括它们的牙齿， 牙菌斑和唾液分布。

And I used friction and wear measurements

我用通过测量摩擦力和磨损程度

to study the effectiveness of that treat on removing plaque.

来研究餐食对去除牙菌斑的效果。

If you're sitting there right now thinking about the last time

如果各位还在纠结 上次没给狗刷牙，

you didn't brush your dog's teeth, you're very welcome.

不用客气。

But what's the big deal with tribology?

但是摩擦学到底有多重要呢？

Let me give you one more example.

再举一个例子，

No matter where you are right now, you got to this location somehow.

不管你现在在哪里， 你总有办法到达这里。

Maybe you walked or rode your bike,

有人走路或者骑车，

but for most people in this room, you probably came in a car.

但是你们大多数人 应该是开车来的。

Just think about all the tribological systems in a car.

想想车里所有的摩擦系统。

You have your personal interactions with the car,

你和车有相互作用，

the car's interactions with the road

车和马路之间也有，

and everything under the hood and in the drivetrain.

以及引擎盖下和传动系统内的一切。

Some routine maintenance is directly connected to tribology.

定期保养与摩擦学就息息相关，

You know how many miles your tires are recommended for using

各位都知道轮胎大概跑 多少路就需要

before you replace them.

检查更换，

你也会规律地检查车胎胎面。

You regularly check the treads on those tires.

You're actively monitoring the wear of your tires.

你其实就是在检查轮胎的磨损程度。

Tribology is the study of wear and friction,

摩擦学研究的是磨损和摩擦力。

and with tires, friction can be the difference between a safe arrival

而对于轮胎，摩擦力

and a car accident.

是旅途平安的关键。

This is because the friction between your tires and the road

因为轮胎和路面的摩擦力

will influence your acceleration, your deceleration

影响着加速和减速，

and your stopping distance.

以及刹车距离。

As a driver, you instinctively already know how important friction is,

作为司机，你知道摩擦力的重要性。

because you know that when the roads are wet,

因为你知道路面湿润时，

they're more dangerous because they're slippery.

开车更危险，更容易打滑。

This is because the water is reducing the friction

这是因为雨水降低了

between your tires and the road.

轮胎和路面的摩擦力。

You may recall that friction is the force that opposes motion,

你们可能还记得， 摩擦力是阻碍运动的力，

so water reducing that force means it's now easier for you to move,

所以雨水降低摩擦力 意味着移动更容易，

hence it's more slippery when the roads are wet.

湿润的路面就会更滑。

Something else to consider

另外还有一件事要考虑进去，

is that overcoming friction takes energy,

克服摩擦力需要能量，

so you're losing energy to friction.

所以摩擦会损耗能量。

This is one way your tires can influence your fuel efficiency.

这是轮胎影响燃油效率的一种方式。

And, in fact, did you know that about one-third of the fuel

你们知道，其实引擎中

that you put into your internal combustion engine vehicle

三分之一的燃油都消耗在了

will be spent overcoming friction?

克服摩擦力上吗？

One-third.

三分之一。

Tribology research has helped us reduce friction

对摩擦学的研究 能帮助我们减少摩擦力，

and therefore increase fuel efficiency and reduce emissions.

从而提高燃料效率，减少排放。

Holmberg and Erdemir have actually done some great studies

霍尔姆伯格和埃尔德米尔 做了一些很棒的研究，

showing the impact tribology research can have

显示了摩擦学研究

on reducing our energy consumption.

对减少能源消耗的影响。

And they found that, looking over the span of 20 years,

他们发现在过去的 20 年里，

we had the opportunity to reduce

我们本有机会减少

the energy consumption of passenger vehicles

高达 60% 的

up to 60 percent.

车辆能源消耗。

When you think about all the cars in the world,

想想世界上的所有车辆，

that's a lot of energy we can save.

我们其实可以节约很多能源。

It's part of the nearly nine percent of our current global energy consumption

作者认为，摩擦学可以 帮助我们节约目前

that the authors identified tribology can help us save.

近 9% 的全球能源消耗中的一部分。

That's a significant amount of energy.

这是个庞大的数字。

So when you look at the numbers, tribology can do some amazing things.

只需要看看这些数据，就会发现 摩擦学多么了不起。

My colleagues have identified up to 20 quads of energy

我的同事已经发现，单单在美国，

we can save across the US alone.

我们就可以节约 20 多夸特的能源。

To put this in perspective:

解释一下：

one quad of energy is roughly equivalent to 180 million barrels of oil,

1 夸特大约相当于 1.8 亿桶石油。

and tribology can help us save 20 times that.

而摩擦学可以帮助我们节省 相当于 20 倍这个数字的能量。

This is through new materials, new lubricants,

我们可以通过新的材料、 新的润滑剂，

novel component design,

以及新的组合设计，

doing things like making wind turbines more efficient and reliable.

来提高风力涡轮机的效率和可靠性。

This happened just by putting 31 people in a room

只需将 31 个人放到一间屋子里，

who viewed the world through a tribology lens.

以摩擦学的角度 来观察这个世界。

Imagine the opportunities that will reveal themselves

想象一下，随着越来越多的人 开始接触摩擦学，

as more of us start to see tribology all around.

这些机会将逐渐展现在我们面前，

My favorite projects right now are in aerospace applications.

我现在最喜欢的项目 是航天应用，

I love reducing wear and friction in these challenging environments.

尝试在充满挑战的环境里 减少损耗和摩擦。

I can make materials and parts

我可以制作能够减少

that will reduce the friction in moving components and engines

运动部件和引擎内部摩擦的 材料和零件，

so that they have less force opposing their motion.

以减少运动阻力。

Less force to move means they require less power,

摩擦力减小， 意味着所需的能量也更少，

so you can use a smaller actuator,

可以使用更小，

which would weigh less,

更轻，

which saves fuel.

也更节能的驱动器。

I can also help make parts that last longer through lower wear.

我制作出的零件 因为磨损小也更加耐用。

This will reduce material waste

这减少了材料浪费，

and also means we're manufacturing the parts less frequently,

也意味着我们 制造零件的频率会降低，

so we're saving energy in manufacturing.

从而节省了生产过程中 所消耗的能源。

I encourage you to start seeing tribology in the world around you

我鼓励大家 关注身边的摩擦学，

and to think about how you would improve those interacting surfaces you experience.

并且考虑如何改善 自己遇到的相互作用面。

Even the smallest improvements

即使是最微小的改善，

really add up.

也可能产生 积少成多的效果。

Tribology may be a funny-sounding word,

摩擦学也许听起来滑稽，

but it has a huge impact on our world.

但它对我们的世界 有着很大的影响。

Thank you.

谢谢。

(Applause)

（掌声）