What are Modulus of Elasticity Units | The Ultimate Guide

 

Hello people. I hope you’re all doing fine. Today I will share an interesting guide on the modulus of elasticity units or young modulus units.

What is Modulus of Elasticity Units – 

The modulus of elasticity means the ratio of the stress applied to material along the longitudinal axis of the specimen tested and the deformation measured on the same axis. In other words, it represents a material’s resistance to elastic deformation. It only applies to the temporary deformation when under stress. Modulus of elasticity is also known as Young modulus or elastic modulus.

When tensile force or stretching force is applied to an object, it expands. The behavioral changes happening can be observed and gained utilizing a stress-strain curve in the elastic deformation region (known as Hooke’s Law). Yes, the expansion or extension produced is heavily dependent on the material, but the factors responsible are the dimensions of the object (thickness, breadth, length, etc.).

A less stretchy material always has a comparatively greater elasticity modulus than a more stretchy or springy object. The definition of stress is the force per unit area of plastic with units Nm-2 or Pa. The young modulus is often represented by the Greek symbol lambda, λ. It is derived when stress is divided by strain.

λ= Stress/Strain – 

• Stress is the force that causes the deformation divided by the affected area.
• Strain is the displacement of the particle of the substance relative to a specific strength.

Image Credit - Matmatch.com

 

σ (stress) = F/A

If I try to simplify the equation and tell the meaning of each character, then σ is stress (in Newtons per square meter), F is force, and A is the cross-sectional area of the specimen.

On the other hand, strain is defined as extension per unit length, and strain has no units as it’s a ratio of units.

ε (strain) = ΔL/L0; ΔL = L-L0

In the above equation, the Lo represents the original length of the bar being stretched, and L represents its length which has been stretched. ΔL is the difference between these two lengths.

E = stress/strain = σ/ ε

Utilizing the measurements of tensile stress and tensile strain, the material’s stiffness is differentiated by the modulus of elasticity which is consent and doesn’t change for a given material. The formula representing the modulus of elasticity is:

E = stress/strain = σ/ ε

Types of Modulus of Elasticity Units –

The two main types of elastic modulus coming under the young’s modulus unit are:

• Shear modulus
• Bulk modulus

1. Shear modulus:

The shear modulus of a material determines its stiffness. It is useful when a force parallel to a given axis is combined by an opposing force, such as friction. In simple words, it’s the likelihood of a material to change from rectangular shape to parallelogram. Shear modulus can be defined as the ratio of shear stress to shear strain and is denoted by the symbols G, S, or µ.

The shear modulus is commonly used in calculations involving two materials in contact and subject to opposite forces. A good example of a phenomenon is rubbing together.

2. Bulk modulus:

The bulk modulus is a thermodynamic property used to measure a material’s resistance to compression. In simple terms, it means the likelihood of the volume of a substance changing without changing its original shape. The ratio is pressure increase relative to volume decrease is what bulk modulus is all about. Denoted by the symbols K or B, the bulk modulus is generally used for observing the properties of liquids under compression.

Interesting Read – What is the Density of Plastics? | The Complete Guide

Applications of Elasticity Modulus Units – 

Elastic modulus plays an essential role in determining the mechanical property of a material. The engineering and medical industry utilizes the elastic modulus the most.

• Essential to select various materials considering how they will be affected under different types of forces and stresses.
• Helping the designing process.
• Determining the batch quality, and reducing the material costs provide much need for consistency in manufacturing.

How to Calculate Modulus of Elasticity – 

Generally, “tensile test methods” are utilized to determine the modulus of materials. These methods include bending test or natural frequency vibration test, and tension test. Bending and tension testing methods follow Hooke’s law and are static methods. Using natural frequency determines an accurate elastic modulus as the test is performed utilizing vibrations.

The static methods are performed by applying quantifiable parallel or perpendicular forces and measuring and calculating the change in length or extent of deformation. Extensometers or mechanical strain gauges are the most preferred devices to perform the operation as they’re good at measuring very small lengths.

The common standards used for determining are:

• ASTM D638 – Test Method for Tensile Properties of Plastics
• ISO 527-1:2012 – Determination of tensile properties.

Engaging Read – What is the Glass Transition Temperature of Plastics?

ASTM D638 and ISO 527 Test Methods:

An Extensometer

ASTM D638 and ISO 527 test methods are utilized to determine tensile properties for plastic materials and plastic composites under specific conditions in the form of standard dumbbell-shaped test samples. Te specified conditions are temperature, humidity, pretreatment, testing machine speed, etc.

The following results can be obtained for the tensile test results:

• Tensile strength
• Tensile modulus/ Young’s modulus
• Strain
• Elongation and percent elongation at yield
• Elongation and percent elongation at break

Talking about ASTM D638 test methods, the test speed is dependent on the specific material. However, for ISO 527 test, the speed is generally 5 or 50mm/min for measuring strength and elongation and 1mm/min for measuring modulus.

Factors Affecting Modulus of Elasticity – 

The modulus of elasticity is related to the atom’s binding energies. The young’s modulus and bending forces are generally higher for high melting point materials. Modulus of elasticity does depend on the positioning of a single crystal material.

The higher temperature in the materials results in a big jump in the atomic vibrations, decreasing the necessary energy to further separate the toms from one another. That decreases the stress needed to produce a certain amount of strain.

Certain things can marginally or heavily weaken or strengthen a material with its presence, such as alloying atoms, impurity atoms, secondary phase particles, non-metallic inclusions, dislocations (mismatches in the lattice structure), and defects (cracks).

1. Anything that hampers the motion of dislocations through the lattice will likely increase the modulus and yield strength.
2. Increased temperature will aid the dislocation movement or create cracks or inclusions that will decrease strength by triggering the early onset of failure.

Interestingly, the modulus of elasticity of plastics falls way below compared to metals, ceramics, or even glass. Below I have shared a table with young’s modulus units of mainstream plastic materials:

Tensile Modulus or Elastic Modulus Units of Mainstream Plastics – 

Fascinating Read – What is Processing and Drying Temperatures of Plastics

FAQs – 

1. Is a higher Young’s modulus better?

Ans. A higher Young’s modulus means more stiffness. In simple words, the elastic strain resulting from applying given stress is smaller. The modulus is an essential metric for determining elastic deflections. Plastics have lower modulus elasticity compared to metals, glass, and ceramics.

2. What are the factors on which the modulus of elasticity depends?

Ans. The modulus of elasticity is dependent mainly on two factors – 1. nature of the material and 2. type of stress used in producing the strain.

3. What is the stiffest plastic?

Ans. A plastic material named Primospire has the stiffest to date.  It has a flexural modulus of 1.2 million psi and a tensile strength of 30,000 psi.

4. What does modulus of elasticity equal?

Ans. Modulus of elasticity is equal to the longitudinal stress divided by the strain. However, the deformation is measured on the same axis.

5. What is the relation between elasticity and modulus of resilience?

Ans. Modulus of elasticity and modulus is a lot more similar to each other than most people know of. The key difference between the both is that the stress is applied slowly in the former, and in the latter, the load is applied rapidly.

Suggested Read – 

• Plastic Abbreviations and Their Salient Features | The Ultimate Guide
• What is Warpage? | Causes of Warpage | Warpage Variations
• 6 Best Plastic Molding Techniques | A Complete Analysis
• What is Rotational Molding | Rotational Molding Process | Advantages & Disadvantages | Best Material for Rotational Molding
• What is Compressive Strength of Plastics | The Complete Guide
• Thermal Properties of Plastics | The Ultimate Guide
• Mold Temperature in Plastics | A Complete Analysis
• Physical Properties of Plastic Materials | The Complete Guide

The Conclusion – 

That’s was all I had to say about the modulus of elasticity and related information. The applications of modulus of elasticity are immense in the engineering industry providing experts with accurate data on plastic stiffness, which helps them make robust products used by consumers like ourselves.

Kindly share your thoughts and reviews in the comment section.

Have a fantastic day.