A24    Discriminate between the definitions of the following terms: flexibility, resilience, impact force, permanent deformation, strength, flexure strength, fatigue, impact strength, toughness, brittleness, ductility, malleability, hardness, abrasion resistance, and relaxation.

Flexibility: The ability of a material to strain without exceeding its elasstic limit.

Resilience: The ability of a material to abssorb energy without permanently deforming.

Impact force: Force hitting a stationary material surface produces an impact force at the location of force interaction.

Permanent deformation: Permanent atomic displacement within a material.

Strength: Ability of a material to withstand forces. Different strength properties exist. For example, the elastic limit can be exceeded (yield strength) or the material may be broken (strength of the material).

Flexural strength: Ability of a material to withstand bending. Dduring bending, complex stresses are induced inside the bent sample. These stresses include tensile, compressive and shear stresses. Failures often occur in regions with tensile stresses.

Fatigue strength: Ability to resist cyclic loading. For example, by rotating a rod that is loaded at one end, tensile stresses are continously induced on the top surface. Even though these stresses may be too low to induce fracture, the rod may fracture after it has rotated a certain number of times for a certain load. The ability to resist fracture during this type of cyclic loading is often referred to as the fatigue strength.

Impact strength: The ability of a material to withstand impact forces.

Tougness: The ability of a material to absorb energy before it breakes.

Brittleness: The lack of a material to deform plastically before it breaks.

Ductility: The ability to plastically deform a material in tension.

Malleability: The ability to plastically deform a material in compression.

Hardness: Ability to resist a localized compressive load without deforming plastically.

Abrasion resistance: Ability to resist material loss when particles are forced along the surface of the body.

Relaxation: Ability of a material to regain its lowest energy level.