Brittle materials include glass, ceramic, graphite, and some alloys with extremely low plasticity, in which cracks can initiate without plastic deformation and can soon evolve into brittle breakage.

• Brittle materials are well known to be much stronger in compression than in tension. This is because under a compressive load a transverse crack will tend to close up and so could not propagate.

In general, soft tough metals will be ductile. Harder, stronger metals tend to be more brittle. The relationship between strength and hardness is a good way to predict behavior. Mild steel (AISI 1020) is soft and ductile; bearing steel, on the other hand, is strong but very brittle.

The ultimate strength is the maximum stress that a material can withstand before it breaks or weakens. For example, the ultimate tensile strength (UTS) of AISI 1018 Steel is 440 MPa.

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Yield strength is used in materials that exhibit an elastic behavior. It’s the maximum tensile stress the material can handle before permanent deformation occurs. Ultimate strength refers to the maximum stress before failure occurs.

The yield strength is often used to determine the maximum allowable load in a mechanical component, since it represents the upper limit to forces that can be applied without producing permanent deformation.

Yield Strength is the stress a material can withstand without permanent deformation or a point at which it will no longer return to its original dimensions (by 0.2% in length). Whereas, Tensile Strength is the maximum stress that a material can withstand while being stretched or pulled before failing or breaking.

As yield strength is related to deformation which is a result of applied stress, the SI unit of yield strength is N.m-2. In CGS system, the yield strength is g.cm-2.

The Effect of Temperature on Young’sModulus. When the temperature increases, the atomic thermal vibrations increase, and this will cause the changes of lattice potential energy and curvature of the potential energy curve, so the Young’s modulus will also change.

For the majority of materials, the yield strength decreases with increasing temperature. In metals, this decrease in yield strength is due to the thermal activation of dislocation motion, resulting in easier plastic deformation at higher temperatures.

Answer. By increasing temperature up to a special value which is around 400 K, Young’s modulus decreases appreciably. For the temperatures higher than 400 K, Young’s modulus decreases with a lower rate and tends to be constant at high temperatures.

(a) Glass is more elastic than rubber because for a given applied force per unit area, the strain produced in glass is much smaller than the strain produced in rubber.

Steel is more elastic than diamond . Steel have youngs modulus value of 200gpa. When a material have larger value of youngs modulus it have less strain cepacity . Between diamond and steel , steel have more elastic nature.