The image above represents flexural strength for rectangular cross-section in defects.

To compute for flexural strength for rectangular cross-section in defect, four essential parameters are needed and these parameters are **Load at fracture (F _{f}), Length of the cross-section (b), Width of the cross-section (d)** and

**Distance between support points (L).**

The formula for calculating flexural strength for rectangular cross-section in defects:

σ_{fs} = ^{3FfL} / _{2bd²}

Where:

σ_{fs} = Flexural Strength

F_{f} = Load at Fracture

L = Distance between Support Points

b = Length of Cross-section

d = Width of Cross-section

Let’s solve an example;

Find the flexural strength when the load at fracture is 10, the length of cross-section is 7, width of cross-section is 9 and the distance between support points is 21.

This implies that;

F_{f} = Load at Fracture = 10

L = Distance between Support Points = 21

b = Length of Cross-section = 7

d = Width of Cross-section = 9

σ_{fs} = ^{3FfL} / _{2bd²}

σ_{fr} = ^{3(10)(21)} / _{2(7)(9)²}

σ_{fr} = ^{(630)} / _{2(7)(81)}

σ_{fr} = ^{(630)} / _{(1134)}

σ_{fr} = 0.55

Therefore, the **flexural strength for rectangular cross-section in defect **is **0.55 Pa.**

**Calculating the Distance Between Support Points when the Flexural Strength for Rectangular Cross-Section in Defects, Load at Fracture, length of the cross-section and width of cross-section is Given.**

L = ^{σfs x 2bd}^{2} / _{3F}_{f}

Where;

L = Distance between Support Points

σ_{fs} = Flexural Strength

F_{f} = Load at Fracture

b = Length of Cross-section

d = Width of Cross-section

Let’s solve an example;

Find the distance between support points when the flexural strength is 20, the load at fracture is 12, the length of cross-section is 7 and the width of cross-section is 9.

This implies that;

σ_{fs} = Flexural Strength = 20

F_{f} = Load at Fracture = 12

b = Length of Cross-section = 7

d = Width of Cross-section = 9

L = ^{σfs x 2bd}^{2} / _{3F}_{f}

L = ^{20 x 2 x 7 x 9}^{2} / _{3 x 12}

L = ^{280 x 81} / _{36}

L = ^{22680} / _{36}

L = 630

Therefore, the **distance between support points **is **630.**