When you are talking about solids and various other materials, it is crucial to understand how these types of materials usually react when a force is applied. This process helps the students identify their strengths, deformations, and various other parameters acting on the objects. And to find these parameters, the stress and strain quantities are important. Here, in this article, we are going to provide a detailed guide about these aspects including how we define stress and strain, their types, and difference between stress and strain. Also let us learn about stress formula and strain formula.

Why is it important to study stress and strain?

It is important to study the stress and strain differences and basics, and stress strain curve, all of which will help in ascertaining the amount of stress or load that a material is capable of handling before it breaks, gets distorted, or stretches. So, the study of stress and strain is all about understanding how and why certain materials are more malleable and can be easily deformed or distorted than others.

Stress is defined as the force per unit area that is observed by a material when an external force is applied. These external forces are generally uneven heating, permanent deformation, etc. These in turn help students calculate and find the plastic, elastic, and fluid behaviour of each material under different forces.

Types of Stress

There are different types of Stress that can be applied to a material, such as

Compressive Stress

When a force acts on a body, it causes a reduction in the volume of the said body, resulting in deformation. This type of stress is referred to as Compressive stress.

Compressive stress leads to material failure that is ultimately caused due to tension. The compressive stress from its application to brittle materials differs from that of ductile materials.

Tensile Stress

When an external force is applied per unit area on a material, and it results in the stretching of the said material, then it is described as Tensile Stress.

Tensile stress leads to elongation of any material due to external stretching force.

What is Strain?

If a body experiences deformation due to the applied external force in a particular direction, it is called strain. Moreover, the strain does not have any dimensions, as it only explains the change in the shape of the object.

Types of Strain

Similar to stress, strain is also differentiated into Compressive Strain and Tensile Strain.

Compressive Strain

Compressive strain is defined as the deformation observed on an object when compressive stress acts on it. And in this type of strain, the length of the material or object generally decreases.

Tensile Strain

The Tensile stress acting on a body or a material that causes the increase in the length of said material is referred to as a tensile strain.

Let’s understand the stress strain diagram in detail,

The OA line represents the Proportional Limit, as it described the region, where the material or body obeys Hooke’s Law. And this line can help students to calculate Young’s Modulus, using the ratio of stress and strain.

Now, the AB line represents the Elastic Limit of the object, which means that after this point, the body does not retain its original shape or size, when the acting force is removed.

As you can guess, the BC lines describe the Yield Point. Which, when force is applied on the material, then there is complete deformation in the object, which cannot be reversed, even if the force is removed.

D point on the graph is the point beyond which students can observe the complete failure of the object, as it crosses the maximum stress a material can endure. This point is stated as Ultimate Stress Point.

E is the Fracture of Breaking Point, at which students can observe the complete failure of deformation of the object, regardless of the force whether it is applied or removed.

Difference between stress and strain

In physics, stress refers to the force that is acting per unit area of the object, whereas strain depicts the ratio of the change in an object’s dimension to its original dimension. In physical parlance, stress is equivalent to Pressure and its unit is Pascal or psi, or pounds. On the other hand, strain signifies the ratio of change in dimensions to that of the original dimension, therefore has no units of measurement. Strain, however, can be measured by strain gauges. Stress and strain curve are related, but are characterized by distinct properties. Stress causes deformation, while strain can be caused by several types of stress, including tension or compression.

Difference between plain stress and plane strain

Plane stress happens when the value of normal stress remains zero and the sheer stress which is seen perpendicular to the direction of the applied load is presumed zero. Plane stress is based on assumption and is measured approximately. On the other hand, plane strain is about distortion in the object that is perpendicular to the object’s plane. If plane stress is more of an approximation, then plane strain is more accurate.

Shear stress and shear strain

Shear stress is the stress that is applied parallel to the plane of the object which renders lateral distortion in the object. As far as shear strain is concerned, it reflects the magnitude of lateral strain in terms of tanθ. Shear Strain is shown as tanθ = Lateral Distortion / Perpendicular height.

Stress and strain are fundamental concepts that play a crucial role in understanding the mechanical behavior of materials. The stress-strain curve provides a graphical representation of this relationship, offering insights into the material’s strength, stiffness, and ductility. By studying stress and strain, engineers and scientists can design and analyze structures and materials to ensure their safety, reliability, and performance in real-world applications.

In the above article, we have explained in detail the terms, stress and Strain, how they act, units of stress and strain, types of stress and strain, etc. This will be helpful for students to solve any kind of problems from these chapters or understand other subtopics easily from the next chapters. However, if you are still worried about how to cover many complex topics and chapters in Physics. Then the best solution for you is to join Online Coaching Platforms. Like the Tutoroot platform, which offers cost-effective online interactive classes that come with various amazing benefits for the students. Visit the Tutoroot site to learn more about these benefits.