Automated Bending Fatigue Tester

1
Automated Bending Fatigue Tester

• Joel Knibbe
• Dale Slotman
• Eric Vander Zee

2
Goal

• The goal for this project is to design, build,
  and test an automated bending fatigue tester, for
  the Padnos School of Engineering.

3
Project Requirements

• Test ¼ round stock
• Test specimens with strengths ranging from soft
  brass to steel.
• Apparatus must mate with the existing Instron
  Tensile Tester.
• Specimen must be in 4-point bending.
• Bar stock must be rotated to produce fully
  reversed bending scenario.
• Apparatus must count the number of revolutions to
  failure, and stop at failure

4
Four Point Bending

• Simply supported from below
• Simply loaded from above

5
Shear Diagram
6
Moment Diagram
7
Selected Concept

• 1 square tubing (1/8 wall)
• 1 square stock
• 1.25 round stock
• Self-aligning rod end spherical bearings

8
Testing Procedure

• Grind a flat on one end of the test specimen
• Insert test specimen through the bearings and the
  universal joint and secure with the setscrew
• Adjust the motor height to minimize the angular
  deflection of the universal joint
• Start and run the fatigue tester method,
  fatigue with the desired load
• Once the full load is applied gradually turn the
  speed control knob to the desired speed
• When the specimen fails, the tensile tester will
  stop and the motor should be stopped

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Test Demonstration
10
Design
11
Design
12
Budget