Flexural strength

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Flexural strength, also known as modulus of rupture, bend strength, or fracture strength,^{[dubious – discuss]} a mechanical parameter for brittle material, is defined as a material's ability to resist deformation under load. The transverse bending test is most frequently employed, in which a rod specimen having either a circular or rectangular across section is bent until fracture using a three point flexural test technique. The flexural strength represents the highest stress experienced within the material at its moment of rupture. It is measured in terms of stress.

For a rectangular sample under a load in a three-point bending setup:

• F is the load (force) at the fracture point
• L is the length of the support span
• b is width
• d is thickness

For a rectangular sample under a load in a four-point bending setup where the loading span is one-third of the support span:

• F is the load (force) at the fracture point
• L is the length of the support (outer) span
• b is width
• d is thickness

For the 4 pt bend setup, if the loading span is 1/2 of the support span:

If the loading span is neither 1/3 or 1/2 the support span for the 4 pt bend setup:

• L_i is the length of the loading (inner) span

See also

• Flexural modulus
• Three point flexural test

References

• J. M. Hodgkinson (2000). Mechanical Testing of Advanced Fibre Composites. Cambridge: Woodhead Publishing, Ltd. p. 132–133.
• William D. Callister, Jr.Materials Science and Engineering.Hoken:John Wiley & Sons,Inc.,2003