Bending 3-point and 4-point Experiment

3-Point Bending

A Three-Point Bend test is performed on a round rod as shown. As a downward force (F) is applied in the middle of the rod, the flex (Δx) is recorded. The ratio (F/Δx) is the effective stiffness of the length of rod being tested.

The distance between the anvils is varied, and the resulting effect on the stiffness of the beam is measured. A graph of the resulting data yields the Flexural Elastic Modulus for the material.

4-Point Bending

A Four-Point Bend Test is performed on the ABS plastic beams from the PASCO Structures System. As a downward force (F) is applied in the middle of the beam, the flex (Δx) is recorded. The ratio (F/Δx) is the effective stiffness of the length of beam being tested, and is measured directly from the slope of the F vs. Δx graph. The Flexural Elastic Modulus for the material is then calculated.

Concepts

• 3-Point Bending
• 4-Point Bending
• Flexural Elastic Modulus

Video

Experiments

• Bending Experiment