Chong Yang: Hi. I'm Chong.
This is Justin, a mechanical engineering student from California State University, Sacramento.
Justin Stewart: Chong, what do we have on the table here?
CY: What we have on the table here is PASCO scientific's material testing apparatus.
The way it works is that it has a manual crank.
The manual crank is connected to an encoder.
The encoder is connected to this leadscrew.
Connected to that leadscrew is a carriage.
That carriage allows you to attach a material sample piece
that's attached to the force sensor
that allows you to find different types of material properties,
both in compression and in tension.
JS: What's all on the table and what comes included with this piece?
CY: Very good question.
What comes out of the box is this material testing apparatus itself.
Safety guards that guards the machine
so that the users don't have to wear safety glasses.
A calibration test piece where you can use our software
to calibrate the unit in order to get relatively very accurate data.
Because our unit uses our PASPORT connection, we have a USB Link
that allows us to connect through a USB connection to a laptop.
Included on top of that, we have a single user license
of our Capstone software that will allow us to do the data analysis itself.
In addition we have a starter kit that is included
to allow the user themselves to start up right immediately out of the box.
In addition to that, if you notice, there's a whole bunch of items in front of you.
What you'll notice is that we also have a shear accessory, a bending accessory,
a flat coupon adapter that allows you to adapt into the machine,
and adapters that allows you to use our series of structure kits
to actually do testing on our structure beams themselves.
The materials that you can actually test it with,
we have annealed steel, regular steel, brass, aluminum,
and two types of plastic. There's a clear type of plastic.
With that, we have a set of polarizing lens that you can attach to the machine itself
to see the polarizer's effect on the clear plastic.
JS: If I were to order one of these,
I get a good variety of different types of samples that comes with it?
CY: Yes, you would get a starter kit that would allow you to start immediately.
JS: Awesome. Do we get to try it out?
CY: Oh, yeah. absolutely. Let's go ahead and remove this safety cover here
and go ahead and grab a brass piece out of our bin here.
What you will like to go ahead and do is remove the spindle, spin the unit in.
I think you might need to lower this carriage a little bit.
Then go ahead and spin the locking spin on top, on top of it.
While you're doing that, what I'm going to do is I'm going to put a
white piece of paper
in order to be able to film with the webcam the actual breakage
of the brass piece itself.
This is not required.
The only why we're doing that is, so that it reduces the reflection on it.
If you notice, there's a webcam already set up
pointing towards the test sample itself.
Are you ready to go ahead and do a stressful/strain example?
JS: Yep, let's do it.
CY: We already have Capstone already up.
The first thing you need to do is go ahead and hit hardware setup to look at your hardware.
What you'll notice is is that there's two icons
that are in that white space.
There's a USB Link icon and a webcam icon.
And it's the Microsoft webcam that's located right here.
Go ahead and plug in the material testing apparatus
into the USB Link itself.
Immediately there's another new icon that is located below the USB Link,
and that is the material testing unit itself.
There's one special other item that we need to do
is that in this unit, travel going up,
because we will do a tensile test, is actually negative,
so we provide a method to go ahead
and switch the sign up so the graph isn't upside down.
Go ahead and click on Properties.
Then go ahead and say Change Sign.
Hit OK.
Then go ahead and close hardware setup.
Then we'll go ahead and enter some formulas in the calculator itself.
In reality, we have a whole bunch of workbooks that allows you to do percent elongation,
Young's modulus, buckling already ahead of time.
What I want to show is how to do this from scratch.
Go ahead and hit on calculator.
Within those workbooks all of equations have been entered in there prior to using it.
You can use it in two ways, pre-packaged, or you can customize the software
itself to be whatever you want it to be.
What's the equation for stress?
JS: Stress is force over the cross-sectional area.
CY: Because we need the cross-sectional area, what happens is I have to provide you some
information about our test sample.
The diameter of the test sample is 3.3 millimeters.
Put diameter is equal to 3.3 millimeters.
What we want to do is we want to use relatively consistent units.
What we're going to do is we're going to do it in meters.
Go ahead and put it in .0033.
Hit Enter.
Hit m for the units of meter. Then hit enter.
I should provide you also the length of the test sample itself.
Go ahead and do L is equal to 35 millimeters.
Put in .035 meters.
OK Good.
Let's go ahead and put the equation in for stress.
Type in stress is equal to...
The force is captured by this, the force sensor itself.
If you right-click and then go Insert Data
and then select force so that
the device will send the force reading to Capstone.
divided by
And then open parenthesis. Diameter divided by two
Squared.
Times Pi within a parenthesis bracket.
Put Pi times that diameter over there.
In order to do that, scroll yourself over to the first parenthesis.
Within it's simple, you can go ahead and choose the constant Pi.
What's the unit for stress in SI units?
JS: Pascal.
CY: Correct. Type in capital Pa.
For us engineers that still works in imperial units, it would be psi.
You are allowed to use psi.
What you just need to do is go ahead and switch the units to reflect psi.
Hit enter.
Then for strain, strain equals...
In order to get delta L, because delta L was equal to position,
right-click,
Insert Data
and Position,
divided by L
What you'll notice is that it says millimeters.
In order to keep our units the same, what we're going to go ahead
and do is click on millimeters and then click on meters.
What I'm going to show you is this is the unit right out of the box
without me calibrating it.
What I want to show you is how does it feel to be a brand new customer using this?
Hit enter. Then what's the unit for strain?
JS: No units.
CY: Correct, that's that trick question. Strain has no units.
Hit delete and hit enter, denoting that it has no units.
Close that by clicking the calculator.
Drag the movie icon, which is located there, into the screen.
Then go ahead and drag it to the upper left corner
or right above the center and treat that a little bit to the left
to make it about a little bit less than half.
Hit record movie with synced data. What that will bring up is a selection for webcam.
Select the Microsoft LifeCam Studio. Hit OK.
What you'll notice is that now we have this webcam shooting the test sample itself.
What that will do is it will film this actual test breakage
sync to the data for stress and strain.
Drag the graph into the screen.
Place it about right here.
What you'll notice is Capstone's smart enough to know
that there's two elements on the screen
and it's going to go ahead and fill half the screen
with the video and half the screen with the graph.
JS: Awe. Nice.
CY: In this case, what we would like to do is then have stress
in this axis and strain in that axis.
Go ahead and click on it.
You can choose a variety of data that you want to show.
Go ahead and select strain and then click back
and then go ahead and hit stress.
In this case, since we're doing stress and strain
and this material is brass,
we know that strain has to be less than one.
Pan the graphed over by clicking on the middle of the graph
and slide that to zero.
We want to expand... go right there.
Then go ahead and drag that do that, because what we want to do is have it zero-zero.
OK Perfect.
Perfect.
What we're going to do next is we can go ahead and pinch and expand the graph more by clicking
a spot on the bottom axis and expand it over.
Then what we're going to do next is we want to
zero the sensor.
You can zero the sensor by clicking on
that zero and two yellow arrow icon.
Now the sensor is zero.
Are we ready to collect some data?
JS Stewart: Yep.
CY: OK. What will happen is go ahead and hit record.
We can go ahead and collect the data for this experiment.
Go ahead and crank it.
You can go as fast, as slow as you want because this is a kinesthetic experience.
You can feel where things are at.
If you wanted to go and break it or you want to stay on the elasticity zone
or plasticity zone,
you can stop and then go back.
In this case, go ahead..... and crank it.....
and then crank it all the way until you break it.
CY: Perfect.
What you notice is that it then shows you data for
both the elasticity, the plasticity, and the yield.
At the same time, you can see that it recorded the video with itself.
For students,
I'm going to ahead and hit stop
so it stops recording data,
but you can go ahead and also play that back
if you want to review how the testing came up.
Do you have any other additional questions for the experiment?
JS: No questions.
I really like how you do the hand crank
and you can control and watch the necking yourself
as you're doing it as opposed to other options.
CY: Correct.
Another good experiment to show is, if you wanted to show hysteresis
you can go ahead and have it go a little bit into
the plasticity range
and then go back into elasticity and show work hardening.
But, I'll let you guys try that on your own.
I would like to thank Justin for being part of this
and I would like to thank you guys for being part of this video.
Thank you.