Mechanical Basics

# Strength of Materials

## What is Strength of Materials?

Strength of Materials or simple SOM is one of the important subjects and almost it is the heart of the Mechanical Engineering field, it is also called as the Mechanics of Strength. It mainly deals with the behavior of materials when some external load is applied to them.

SOM will explain the stresses, strains, breaks, fracture, and their different types that will be developed in a material. The behaviour of a material helps to Research, Design, and Decide either it is suitable for a particular application or not.

For example, We use Stainless Steel utensils in our kitchens for cooking food, it means the utensil we used to cook should absorb the heat the transfer to the other end by withstanding for heat up to a certain point; whereas such estimation, selection of material for utensils and designing can be done only when we are aware of the material’s behavior.

So, the Strength of Material or SOM is the subject that helps us to learn about them.

1. Strength of Materials Syllabus.
2. Strength of Materials Basics & Strength of Materials Formulas.
3. Types of Beams and Loads.
4. Strength of Materials Books. (for reference)

## Strength of Materials Syllabus:

The syllabus is the particulars we read or learn in our semester or academics. As the syllabus will vary according to their University, so I listed out the important syllabus that everyone will follow, and this syllabus is equal to GATE (Graduate Aptitude Test in Engineering).

• Shear & Bending Stresses and their Slopes, Deflections.
• Columns and Energy Methods.

The Strength of Materials Syllabus or SOM Syllabus will be frequently updated according to the new pattern.

##### Strength of Materials Basics & Strength of Materials Formulas:

Stress:

Stress is defined as the internal forces that resist external forces when applied in a particular body. The mathematical expression for stress is

F=Force Acting on the Body in Newtons.

A= Area that force is acting in meter or square meter

It is expressed in terms of pascal Pa or N/mm2 also.

Strain:

When a force is applied to a body, due to its elastic property it will deform. So, Strain is defined as the ratio of deformation per unit length or area. The mathematical expression for Strain is

Here, dl is the change in length when the load is applied and l is the original length of the body.

Tensile stress:

When two equal and opposite axial pulls are subjected to a body, then the body will resist those forces, such stress are called Tensile Stress.

Tensile Strain:

When two equal and opposite axial pulls are subjected on a body, then the body gets deform and results in a change in the length. Such strain is called the Tensile Strain.

Compressive Stress:

When two equal and opposite axial pushes are subjected to a body, then the body will resist the forces in the axial direction. Such axial stress is called compressive stress.

Compressive Strain:

When two equal and opposite axial pushes are subjected to a body, then the body will get deformed. Such deformation is called the Compressive Strain.

Shear Stress :

Shear Stress is defined as a body is subjected to tangentially two equal and opposite forces, then the body gets sheared in that section. Such stress-induced in the body is called Shear stress.

Shear strain:

Shear Strain is defined as that a body is subjected to a tangentially two equal and opposite forces, then the body sheared and strain will be developed in it is called as the Shear Strain.

Young’s Modulus:

Young’s Modulus is also called the Modulus of Elasticity. It is defined as when a material is loaded within elastic limit then the stress and strain will be developed in the body, such stress is directly proportional to the strain. Such a process or law is also called Hooke’s Law. It is denoted as ‘E’. The mathematical formula is given by

Modulus of Rigidity:

Modulus of Rigidity is also called the Shear Modulus; the shear stress is directly proportional to the shear strain within its elastic limit is called as the Modulus of Rigidity. It is denoted as the N or G.

Linear strain:

Linear Strain is the deformation of the object per unit length developed in the direction of the force applied. It is also called the Primary Strain.

Lateral strain:

Lateral is the strain developed in its own direction and an opposite in every direction and also at the right angle is called the Lateral strain. It is also called the Secondary Strain.

Poisson’s ratio:

It is the ratio of the Lateral strain to the Linear Strain in an object.

Volumetric Strain:

When a force is applied on the body, then the volume will change then the ratio change of volume to the original volume is called the volumetric strain.

Bulk Modulus:

Bulk Modulus is the ratio of Direct Stress to the corresponding Volumetric Strain. It is taken when a body is subjected to three mutually perpendicular stresses of equal intensity. In such cases, Bulk Modulus is considered.

Resilience:

Resilience is the energy stored in a body due to the loading of external sources within its elastic limit.

Brittleness:

The brittleness is a property of material; whenever an external load is applied, the material will deform and failure or fracture without any significant symptoms. It has high compressive strength and low tensile strength which makes it weaker in impacts loads.

Ductility:

The ductility is also a property of material; that the material will deform permanently without any failure or fracture. It is also the property that allows the materials to draw into thin sheets. These types of materials are soft in nature.

Ferrous Materials:

Ferrous Materials are the type of materials that do consists of iron in its composition. The examples of ferrous materials are Cast Iron, Steel, their alloys, etc.

Non-Ferrous Materials:

Non-Ferrous Materials are the type of materials that does not consists of iron in its composition. The examples of non-ferrous materials are Rubber, Plastic, etc.

Till Now we studied about the basics of this subject. Now we are going learn about the types of Beams and Loads.

## Types of Beams and Loads:

We can find five types of Beams. They are

• Cantilever Beam.

It is a type of beam where one end is fixed and another end is left freely.

• Simply Supported Beam.

Simply Supported Beam is a type of beam where it is supported at its both ends.

• Continuous Beam.

If a beam is supported on more than two, then such beam is called as the Continuous beam.

• Fixed Beam.

If a beam is fixed at its both ends, such beam is called as the Fixed Beam.

• Overhanging Beam.

A beam having its end portion extended beyond the support is called as the Overhanging Beam

There are three types of Loads. They are

If a load acting at a single point on a beam, then it is called the point load. It is also called the Concentrated Load.

If a load is applied over a beam and each unit length should be loaded with the same extent, then such loading is called as the Uniformly Distributed Load.

If a load is applied all over a beam and each unit length should be varied uniformly, such loading is called as the Uniformly Varying Load

## Strength of Materials Books:

Student needs to refer the textbooks to grab the knowledge that not even found in the classroom teaching. When the student starts referring to the textbooks then the seed of knowledge will start growing in oneself. So, do not stick to the classroom notes but also try to refer to the textbooks that increase the knowledge.

Here I am mentioning a few references, please go through them.

• Strength of Materials by R K Bansal.
• Strength of Materials by R K Rajput.
• Strength of Materials by Timoshenko.
• Strength of Materials by R S Khurmi.

Note: Please refer to the syllabus in each textbook before you refer to or purchase.