Brittle fracture is a material failure with very less plastic deformation. The brittle fracture never shows any macroscopic signs before the fracture.
Contents:
What is Brittle fracture?
Brittle fracture is the fracture that occurs in material with very little or no plastic deformation.
In such cases, there is no macroscopic deformation occurs before the fracture in the material.
The brittle fracture absorbs less energy as compared to the ductile fracture. The breaking strength for the brittle fracture is equal to the ultimate tensile strength.
Brittle fracture stress strain curve:
The above figure shows the stress-strain curve for the brittle fracture.
As shown in the figure, the material fails after the elastic point without showing any plastic deformation.
The area covered below the stress-strain curve shows the energy absorbed by the material before failure.
The area covered by the stress-strain curve for the brittle fracture is less in comparison with a stress-strain curve for ductile fracture. It means that the energy absorbed by the object for brittle fracture is less as compared to the ductile material.
Brittle fracture equation:
As per the Griffith theory, the stress required for the propagation of a crack in a brittle material is given by,
`\sigma` = `[\frac{2E\gamma_{s}}{\pi a}]^{\frac{1}{2}}`
Where,
`\gamma_{s}` = Surface energy
E = Modulus of elasticity
a = Crack length
Brittle fracture examples:
The brittle fracture occurs in the following brittle materials:-
- Glass
- Cast iron
- Stones
- Ceramics
Brittle fracture vs ductile fracture:
Here are some points that differentiate between ductile and brittle fracture:-
| Sr. No. | Brittle fracture | Ductile fracture |
|---|---|---|
| 1] | The brittle fracture occurs with very less plastic deformation. | The ductile fracture occurs after the considerable plastic deformation. |
| 2] | The brittle fracture absorbs less energy as compared to ductile fracture. | The ductile fracture absorbs more energy. |
| 3] | In brittle fracture, the propagation of the crack occurs rapidly. | In ductile fracture, the crack propagation is slower. |
| 4] | The brittle fracture occurs with the formation of cleavage. | The ductile fracture occurs with the formation of cup and cone shapes. |
| 5] | Examples: Glass, Ceramics, stones, Chalk, etc. | Examples: Copper, Aluminum, Gold, etc. |
FAQ’s
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What causes brittle fracture?
The presence of defects during manufacturing (notches, cracks formed during the machining processes) causes stress concentration into the material which leads to the brittle fracture.
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How do you know if you have a brittle fracture?
The brittle fracture shows very less or no plastic deformation with the presence of cleavages on the fracture surface.
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What are the characteristics of the surface of a brittle fracture of a metal?
The characteristics of brittle fracture are: Less plastic deformation and the Formation of cleavages.
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At which point does brittle fracture occurs?
The brittle fracture occurs at the yield point of the material.
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