Flexural Test

Specimen supported at 2 ends. Load $P$ applied perpendicular at the midpoint (3-point bending) until fracture.

The MOR (Modulus of Rupture) is the maximum stress at the fracture surface:

Here:

• $P$: fracture load
• $L$: support span length
• $b$: width of specimen
• $d$: depth of specimen

MOR is equivalent to the tensile strength in bending, not in pure tension.

Failure Mode

Brittle materials fracture on the tension side (bottom face). Tensile stress exceeds compressive stress at fracture for materials with no plastic deformation.

Comparison to Tensile Test

Brittle materials (ceramics, glass) are difficult to grip without introducing stress concentrations in a tensile test. The flexural test avoids this: the specimen is simply supported and loaded in bending, making it the standard test for brittle materials.