Home >> Science & Nature >> Science

How to Set Up a Two-Point Bending Test

When you want to test the strength and fatigue, or weakness, of a fiber, the two-point bending test is a suitable method. A two-point bending test allows observers to analyze how effectively the fiber can hold up when bent at an angle of 180 degrees through the force of two equally sized objects, called faceplates. Acoustic sensors are used in this test to send signals to a computer software program that tells observers the exact point in which the fiber breaks, so that they may determine the strength and fatigue rates.

Things You'll Need

Fiber
2 faceplates
Acoustic sensor
Translation stage
Mounting plates
Mounting brackets
Electric drill
Stepper motor
Motor drive
Digital controller
Sensor cables and connectors
Computer and software

Instructions

- 1
  Position the fiber into the two faceplates. The faceplates are on either side of the fiber and have special grooves where the fiber is inserted into place. The fiber must fit into the grooves in order for the fiber to stay stationary during the two-point bending test. Make an upside down "U" with the fiber so that the two ends of the fiber are latched into the faceplates at the bottom, and the top of the fiber is rounded at the 180-degree mark.
- 2
  Attach the acoustic sensor to the exterior side of one faceplate. The acoustic sensor is what will read the strength or fatigue. The acoustic sensor that you purchase for this test may have one side that is already an adhesive. The adhesive side is what you affix to the side of the faceplate.
- 3
  Set up the translation stage on the opposite faceplate from where the acoustic sensor is located. So, if the acoustic sensor is on the exterior of the left faceplate, position the translation stage on the exterior of the right faceplate. The translation stage is the device that applies pressure to the faceplates to bend them together to test the strength and fatigue of the fiber. Affix the translation stage to the faceplate with mounting plates, using mounting brackets and an electric drill to secure the connection.
- 4
  Place the stepper motor on the open side of the translation stage. The stepper motor is the motorized device responsible for generating the power that causes the translation stage to apply pressure to the faceplates. The stepper motor is powered by the motor drive, and the operator of the test is in charge of using a digital controller to tell the motor drive what to do. More mounting plates, mounting brackets and an electric drill are used to affix the stepper motor to the translation stage.
- 5
  Set the sensor cables and connectors in position between the acoustic sensor faceplate to the computer, and the stepper motor drive to the computer. All of the sensor cables and connectors must be in place in order for the computer system to receive signals and readings on the test.
- 6
  Set all of the dials in the computer bending test program to prepare for the test. Input all of the existing data, such as the "Experiment Parameters" and "Fiber Parameters" into the appropriate fields. As soon as the computer program is ready, you can begin the test.

Science