CIE 111: Civil Engineering Materials Laboratory
links: [ Up ]

CMT
program

Instron Corporation

Small capacity mechanical (screw driven) machine typically used for accurately strained tension and compression.

Originally purchased using Civil Engineering Alumni Donations, it was retrofitted with a new controller system in 2001.  Thanks to Instron Corporation for the donation and College of Engineering Curriculum Fee monies!

Operating Instructions

Sometimes use the Instron computer with LabView software, sometimes manually

Load (kips)	Crosshead Displacements (inches)	Strain (%) NOT decimally correct		use "Track" to show current numbers

Compression Testing

Do once to setup machine:

1. Turn machine on - one switch on frame
2. Press load cal and enter - electronically calibrates load cell
3. Press load bal and enter - zeroes load readout
4. Press speed, enter 0.25 (in/min), press enter
5. Position the crosshead substantially above the specimen, say 1/4" using jog buttons
6. Press G.L. reset to zero the crosshead movement
7. Be sure that the display mode is "Track" - button below strain display

Running Compression Tests:

1. Center the specimen under loading head
2. Use jog button to apply a small load, say under 50 lbs.
3. Press down button (arrow down) to start testing
4. Watch load increase to peak and record
5. Press red stop button to stop test, then yellow return button to move crosshead back
6. Repeat for all 30 specimens

Tension Testing

Do once to setup machine:

• In addition to the compression testing list above, Press strain cal and enter - electronically calibrates extensometer. (button is right next to Load Bal button)

Performing Tension Tests:

1. Place one end of the specimen in the top grip of the Instron testing machine with the punch marks facing toward the rear of the machine. The lab instructors will help you place the Extensometer on specimen. The extensometer should be facing toward the front of the machine.
   
2. Zero the strain (Strain Bal and <enter>) and load (Load Bal and <enter>).
3. Apply the bottom grip to the specimen.  This will result in some load and strain.
4. Zero the crosshead movement (G.L. Reset).
5. Press the IEEE button to transfer control of the machine from the console to the computer. 
6. Use a crosshead movement rate of 0.1 in/min.
7. Observe the load readings and elongation readings from both the extensometer and the crosshead movement. Notice that when the yield point is reached, the load reading will start to fluctuate, marking the beginning of the plastic region. At the end of the plastic region, the load readings will start to increase steadily again, marking the beginning of strain hardening. When the ultimate strength point is reached, the load readings will start to decrease steadily, marking the beginning of the necked down region.
8. Just after the load reading begins to go down, your instructor will help you carefully and quickly remove the extensometer. The extensometer must be removed after ultimate strength is reached, so that it is not damaged when the specimen breaks.
9. After rupture, stop the test. Copy the Excel file that contains the data onto a 3.5 inch disk. The file has four columns of data.

   Time (milliseconds)

   Load (kips)

   Crosshead Displacements (inches)

   Strain (%) NOT decimally correct

Tips

• To transfer control to the computer press the IEEE button (right below speed button).