Mechanical Properties of Materials : Discover Their Meaning and Definition !!

Abstract

Mechanical properties are used to help classify and identify material. The most common properties considered are strength, ductility, hardness, impact resistance, and fracture toughness. Most structural materials are anisotropic, which means that their material properties vary with orientation.

Keywords

Mechanical Properties of Materials, Strength, Ductility, Hardness,Iimpact Resistance, Fracture Toughness.

Learning Outcomes

After undergoing this article you will be able to understand the mechanical Properties of Materials

1. What's Mechanical Properties of Materials?

A material’s property is an intensive property of some material, i.e., a physical property that does not depend on the amount of the material.

These quantitative properties may be used as a metric by which the benefits of one material versus another can be compared, thereby aiding in materials selection.

A property may be a constant or maybe a function of one or more independent variables, such as temperature. Materials properties often vary to some degree according to the direction in the material in which they are measured, a condition referred to as anisotropy.

2. Mechanical Properties of Materials with their meaning / definition 

Brittle: Materials that have a tendency to break easily or suddenly without stretching or bending first.

Ceramics: Ceramics are not shiny unless glazed, hard, often brittle, heavy, can be any colour (often white, pale brown to dark brown), cold to the touch.

Conductivity: How well a material conducts heat and electricity.

Corrosion resistance: The ability to withstand environmental attack and decay.

Density: Density is mass per unit volume. The unit of density is the Kg per metre cubed.

Ductility: The ability to be pulled into a thin wire or threads. Good examples are gold, copper and brass.

Elastics: The ability of a material to return to its original shape after a force has been applied and removed.

Flexibility: The ability to cope with bending forces without breaking.

Hardness: A measure of how easily a material can be scratched or dented.

Malleability: The ability to shape a material by applying pressure or a force. Good examples are lead, gold and copper.

Metals: Metals are shiny, hard, heavy, good conductors, can be polished and are cold to the touch.

Plastics: Materials that change shape permanently when small forces are applied. Plasticine and clay are good examples.

Stiffness: The ability to resist bending.

Strength: The ability of a material to withstand forces.

Tough: Materials that absorb forces – the opposite to brittle materials.

3. Other Mechanical properties

• Brittleness: Ability of a material to break or shatter without significant deformation when under stress; opposite of plasticity, examples: glass, concrete, cast iron, ceramics etc.
• Bulk modulus: Ratio of pressure to volumetric compression (GPa) or ratio of the infinitesimal pressure increase to the resulting relative decrease of the volume
• Coefficient of restitution: The ratio of the final to initial relative velocity between two objects after they collide. Range: 0-1, 1 for perfectly elastic collision.
• Compressive strength: Maximum stress a material can withstand before compressive failure (MPa)
• Creep: The slow and gradual deformation of an object with respect to time. If the s in a material exceeds the yield point, the strain caused in the material by the application of load does not disappear totally on the removal of load. The plastic deformation caused to the material is known as creep. At high temperatures, the strain due to creep is quite appreciable.
• Durability: Ability to withstand wear, pressure, or damage; hard-wearing
• Fatigue limit: Maximum stress a material can withstand under repeated loading (MPa)
• Flexibility: Ability of an object to bend or deform in response to an applied force; pliability; complementary to stiffness
• Flexural modulus
• Flexural strength: Maximum bending stress a material can withstand before failure (MPa)
• Friction coefficient: The amount of force normal to surface which converts to force resisting relative movement of contacting surfaces between material pair
• Mass diffusivity: Ability of one substance to diffuse through another
• Poisson’s ratio: Ratio of lateral strain to axial strain (no units)
• Resilience: Ability of a material to absorb energy when it is deformed elastically (MPa); combination of strength and elasticity
• Slip: A tendency of a material’s particles to undergo plastic deformation due to a dislocation motion within the material. Common in Crystals.
• Specific modulus: Modulus per unit volume (MPa/m^3)
• Specific strength: Strength per unit density (Nm/kg)
• Specific weight: Weight per unit volume (N/m^3)
• Stiffness: Ability of an object to resist deformation in response to an applied force; rigidity; complementary to flexibility
• Surface roughness: The deviations in the direction of the normal vector of a real surface from its ideal form
• Tensile strength: Maximum tensile stress of a material can withstands before failure (MPa)
• Viscosity: A fluid’s resistance to gradual deformation by tensile or shear stress; thickness
• Young’s modulus: Ratio of linear stress to linear strain (MPa)

4. How do engineers determine the mechanical properties of various materials?

The tensile test is a standardized method to determine the materials mechanical properties. This method is performed by holding a sample, called specimen, in a rigid device and increasing the load or the stress applied to pulling on the sample until failure occurs.

5. Conclusions

Mechanical properties are fundamental in determining the suitability of a metal for a specific application. These properties define how a metal reacts under various forms of mechanical stress, such as tension, compression, and shear. Understanding these properties is crucial for engineers and manufacturers to select the right metals for the intended use, ensuring reliability and safety.

6. FAQs

Q. What's the Importance of Mechanical Properties in Metal Manufacturing?

Ans.

Understanding a metal’s mechanical properties is crucial for selecting the right material and processing techniques. Each application requires specific mechanical properties to ensure optimal performance and safety. For example:

• Structural components require high strength, toughness, and ductility to withstand heavy loads and impacts.
• Automotive parts need high strength, hardness, and wear resistance to withstand constant friction and stress.
• Cutting tools require high hardness to maintain sharpness during use.

By considering a metal’s mechanical properties, manufacturers can design products with the desired characteristics, ensuring reliability and performance.

References

Mechanical Properties of Materials (Solid Mechanics and Its Applications Book 190): By Joshua Pelleg, available on Amazon.in 

Mechanical Properties of Engineered Materials: By Wole Sob, available on Routledge 

Mechanical Properties and Working of Metals and Alloys: By Amit Bhaduri, available on Springer Singapore

Knovel: Includes Newnes Engineering Materials Pocket Book by William Bolton,

 Encyclopedia of Nanotechnology, 

Encyclopedia of Iron, Steel, and Their Alloys, and 

Encyclopedia of Materials: Metals and Alloys 

IOPscience: Includes a book chapter on mechanical properties of materials