Determining Flexural Properties of Ceramic Whiteware ASTM C674
ASTM C674 determines flexural properties of Ceramic Whiteware by calculating the modulus of rupture and modulus of elasticity. Flexural properties are the properties that describe how material gets deformed. Standard values are reported in imperial units.
ASTM C674 determines two things: the modulus of rupture and the modulus of elasticity. These two parameters are used by materials engineers to describe how material gets deformed. Both are written in product specification.
The main difference between modulus of elasticity and modulus of rigidity is that the modulus of elasticity describes how material gets deformed when a force is applied at right angles to a surface of an object, causing the material to elongate or shorten while the modulus of rigidity describes how material gets deformed when a force is applied parallel to a surface of an object, causing one of the surfaces to shift relative to another surface of the same object.
In ASTM C674, the ceramic sample is placed on two ridges and a direct load is applied at the midpoint of the sample until the sample breaks. The modulus of elasticity is determined by halting the applied load at definite intervals and measuring the deflection of the specimen at the midpoint to the nearest 0.001 inches.
At least 10 samples are needed. The sample needs to be approximately 1.125 inch, 0.750 inch, 0.500 inch, or 0.250 inch in diameter, whichever diameter is most comparable to that of the finished product. The length needs to be approximately 0.50 inches to permit an overhang of at least 0.25 inches at each end when mounted on the supports. The dry-pressed specimens need to be rectangular bars approximately 1 inch by 0.50 inch in cross-section and at least 4.50 inches in length to permit an overhang of at least 0.25 inches at each end when mounted on the supports.
Modulus of rupture
For circular specimen:
M = 8PL/πd3
2. For rectangular specimen:
M = 3 PL/2bd2
where: M = modulus of rupture P = load at rupture L = distance between supports d = diameter of specimen
Modulus of elasticity
For circular specimen
E = 4WL3/3π∆d4
2. For rectangular specimen
E = WL3/4∆bd3
Where: W = load coordinate of the selected point. D = deformation coordinate of the selected point. b = width of specimen at the center