
English: 
Hi. My name is Mark Bailey. I’m an application
engineer here at Agilent Technologies and
today I’d like to talk to you about measuring
force, both dynamic force and static force.
So what do I mean by dynamic force? Well,
think of a string on a guitar that’s plucked,
and it’s vibrating, going back and forth.
You want to measure the force that’s being
generated by that. Maybe the force on an 
airplane wing, where it’s bouncing around, or 
a microphone, where you’re talking to it
and it’s picking up the signal.
There’s a couple of different sensors that
are used for this. One of them is the piezo sensor.
It’s basically a crystalline structure
that generates a voltage as it’s tweaked on.
It’s a little like your old phonograph
records, where they used to have a crystal
and a little needle, and as the needle vibrated
in the grooves it generated a voltage coming

Chinese: 
您好，我是安捷倫科技
應用工程師Mark Bailey
今天我要介紹應力量測
包含動態與靜態應力
什麼是動態應力？
舉例，彈奏吉他時
吉他弦會來回振動
此時可量測彈奏時產生的應力
此外飛機機翼上下震動
或是對著麥克風說話而產生信號等
都算是動態應力
您可使用某些感測器來量測這類應力
例如壓電感測器
壓電感測器採結晶構造
可在待測物上產生電壓
這跟老式黑膠唱片播放機的原理很像
播放唱片時，唱針在石英軌跡上轉動
其振動會導致石英產生電壓

Chinese: 
現在請看電壓錶
螢幕中顯示量測電壓為0 V
基本上電壓錶沒有在運作
當我拿起電線任意撓折時
電壓錶就會開始量到電壓
只要我停止彎折 
量測電壓馬上就會掉回 0 V
擷取到剛剛敲擊電線所產生的電壓後
我把資料輸入電腦
並透過軟體繪出圖形
您可以看到
每次敲擊電線就會產生脈衝
停止動作就會回到 0 V
這是量測動態應力的好方法
但卻不適合用來量測靜態應力
那麼該如何量測靜態應力呢？
我用體重計來舉例
體重計量到我的體重是200多英磅
它會持續不斷的量測
即便所量測的物品重量並未改變
這是靜態而非動態量測
接著我要示範如何使用應變規
來進行靜態量測
我先執行一些設定就可開始
量測靜態應變或應力了

English: 
out of the crystal. Okay, so if you look on
the voltmeter, you’ll notice that I’m
measuring basically zero volts while it’s
sitting here just dead. As soon as I pick
it up and starting twisting on it and banging
it around, you’ll notice that it’s generating
a voltage. But as soon as I quit 
doing that, it drops back to zero volts.
Okay. I actually captured that. I sat there
and kind of did this and just banged on it
and captured it with the multimeter and brought
that information in and plotted it out. And
if you look on the screen, you can see that
each time I whacked it, it got another pulse
on it. But then as soon as I stopped banging
on it, it went to zero. So great for dynamic,
but not very good for static measurement.
What do I mean by static measurement? 
Well, think about a scale. You step on the 
scale. It weighs you. In my case, it says it’s
200-plus pounds, and what you get is a constant
measurement, even though things aren’t changing.
It’s not dynamic; rather, it’s static. So I’m
going to show you a demonstration of making
static measurements using something called a
strain gauge. So let me go ahead and set that up.
Okay. So we’re set up to make a static 
strain measurement or force measurement. 

Chinese: 
這個是應變規
它在一片小小的塑膠基板上
來來回回佈滿軌跡線
這些線路彼此保持一定的間距
因此可形成很多的電阻器
350歐姆是標準值
剛剛好就是現在的讀值
當應變規拉長時
電阻值會增加
受到壓縮時
電阻值會下降
應變規通常被放入惠斯登電橋中
以便激發並產生電壓
惠斯登電橋有一個平衡電橋
以及1, 2 或4支腳
每支腳都有一個應變規
可用來量測電壓
聽起來很複雜
我要用34411A來展示
然後使用應變規執行4線歐姆量測
量測結果會跟先前的量測很相近
我已經有應變規了
我把4線纜線分別接到兩端
電壓錶持續顯示349的讀值

English: 
We’re going to do that using something called a
strain gauge. A strain gauge is just basically
a bunch of traces laid down on a little plastic
substrate going back and forth and back and forth.
And you get enough distance there and it
actually turns into a pretty good size resistor.
Three hundred and fifty ohms is
a fairly standard value and that’s what
we have here. Usually, when a strain gauge
gets elongated, the resistance goes up and
when it gets compressed, the resistance goes
down. The way people usually measure this
is they put them in something called a 
Wheatstone bridge. They have an excitation voltage. 
They have a balanced bridge and one, two, 
or four legs have strain gauges in them and 
they measure a voltage across it.
Well, it’s pretty complicated. What I’m
going to show you is with the 34411A, we can
take a 4-wire ohms measurement of that 
same strain gauge and get a similar result.
So, I’ve got my strain gauge here. I’m running
four wires back for a 4-wire ohm measurement
on it, and you can see I’ve got a stable
reading, around 349. As I push on the cantilever,

English: 
it goes into tension on the strain gauge and
it goes up. And as I come in and lift it,
now I’m going into compression and the number
goes down. And then when I got back to the
stable zero position, it comes back to where
it was before. Okay. So think of it being
a weight and I’m standing on the scale 
and I’m pushing it down, and the number 
goes up and I can measure that.
Now, we’re actually able to measure microstrain
if we do all the appropriate things with gauge
factors and calculations and stuff, but I’m
just going to show you the principle here first.
Now, it shows up even better if I go
into null, and now I’ve nulled out that
initial stable position, and now it’s even
more clear. As I push down on it, the numbers
go up. As I lift on it, the numbers go down,
Okay, it goes negative. What I’d like to
do now is go ahead and set up my computer
to take control of the 34411A. The 34411A
has a built-in Web server, and with my Web
browser I’m going to go in and take control
of the instruments. Let me go ahead and do that.

Chinese: 
壓一下懸臂，應變規會感受到張力
導致電壓上升
將懸臂抬高，應變規會感受到壓縮
電壓錶的數值會下降
放開後，則回到原先的數值
假設我現在站上體重機
應變規感受到壓力後
會導致體重機的數值增加
這樣我就知道我的體重
同樣方式可量測微應力
只要執行所需的步驟並進行計算即可
我先示範一些基本原則
如果設成空值
可以更清楚呈現量測過程
我把原先的數值設成空值
然後開始往下壓
量測數值會不斷增加
把它往上抬，會開始出現負值
接著我要設定電腦以便控制34411A
34411A有內建的網頁伺服器
我要透過瀏覽器登入該網頁
以便控制34411A

Chinese: 
我先點選browser control 
再選擇allow full control
此時螢幕中出現了萬用電錶
0:04:06.359,0:04:12.480
我要到下方的控制面板進行設定與調整
先設定4-wire ohms
Offset Compensation設成off
Auto Range不變
我想加快量測速度
所以設成0.006 PLC，即每秒1,000筆讀值
接著勾選Enable Null
以確保讀值還是0
Trigger Source設為immediate
Sample Count設成 10,000 counts
不過我懷疑可以執行這麼多次取樣
不過我還是設定成這樣
接著按Apply鈕就好了
完成儀器設定後
現在可以開始量測了
開始量測後
我會彎折懸臂並放開
讓它上下擺動
以便擷取諧振

English: 
Okay. So here’s my Web browser. I’m going
to go into the browser control and I want
to allow full control, so I go ahead and click
that. There it is, monitoring the multimeter,
and I’m getting readings. I come down here
and I set up the control panel so that I can
adjust it. I’m going to want to be in 4-wire
ohms. I’ve got Offset Compensation off.
It’s fine to be in auto range. I’m actually
going to go pretty fast. I’m going to change
this to 0.006 PLC, which is about 1,000 readings
a second, and I’m going to Enable Null,
so sure enough, I’m still in zero. I want
to trigger immediately. I’m going to take
about 10,000 counts I’m going to set it
up for. I doubt if I’ll take that many counts,
but I’ll set it up for it, and I’m going
to go ahead and apply that to the instrument.
Okay. So my instrument’s changed. It’s
set up and ready to go on the measurement.
What I’m going to do is start the measurement
and then I’m going to bend my cantilever
and then let it bounce back up and down and
capture that kind of resonance. So I start

Chinese: 
我先按Start Meas
壓下懸臂後讓它上下擺動
接著按Stop Meas
現在可以查看讀值了
現在會出現一堆的資料
就是填滿最下面方框的數據
我先按Control-A進行全選
按Control-C複製資料
然後把資料貼到Excel表
按Control-V把資料貼到Excel表後
就可以開始繪圖
先點選插入、折線圖
就會出現最終的圖形
我把圖放大一些
您可以清楚看到隨著震動
而產生的不斷上下波動的波形
以上介紹了動態與靜態應力量測
包括使用壓電感測器來量測動態應力

English: 
the measurement, I push down on the 
thing, let it bounce for a while. Okay.
Stop the measurement, and now I’m
going to go in and view the data. I should
have a bunch of data now that came from that.
Okay, and I’m going to get the data, and
the data fills up the window. I’m going
to come in here and capture the data. 
I’m going to do a Control-A to highlight it 
all and a Control-C to capture it. And now 
I’m going to go to an Excel spreadsheet and I’m
going to populate that spreadsheet with that
information. So I do a Control-V and what
I want to do is actually go in and graph it.
So I’m going to go to where my graphing is,
grab a graph, do the graph, and lo and behold,
you can see what all was going on.
As I expand this out, you can really see what
was going on with the measurement. Okay, went
up, I held it, let it go and it vibrated down.
Okay. So we’ve seen both dynamic and static
measurements using either a piezo sensor in

English: 
the case of dynamic or in static force 
measurements, we used a strain gauge measurement. 
I hope this was clear and I thank you for joining
me. I look forward to seeing you again next time.

Chinese: 
以及使用應變規執行靜態應力
希望以上的講解夠清楚
感謝您的收看，下次見！
