Understanding the Parameters of Tensile Testing: Load, Elongation, and Strain

Tensile testing is a widely used method for evaluating the mechanical properties of materials under tension. When conducting a tensile test, several parameters are measured to understand the material's behavior under stress. The three primary parameters measured in a tensile test are load, elongation, and strain. In this blog post, we will discuss these parameters and their importance in tensile testing.

Load: Load is the amount of force applied to a material during a tensile test. The load is typically measured using a load cell, which converts the force into an electrical signal that can be recorded. The load is usually plotted against the elongation or time to create a load versus displacement (or load versus time) curve. The load versus displacement curve shows the amount of force required to stretch the material as it is elongated.

Elongation: Elongation is the change in length of the material due to the applied load. The elongation is measured using an extensometer, which is a device that measures the change in length of the material during the test. The elongation is usually plotted against the load or time to create an elongation versus load (or elongation versus time) curve. The elongation versus load curve shows the amount of deformation or stretching that occurs in the material as the load is increased.

Strain: Strain is a measure of the deformation of a material relative to its original length. Strain is calculated by dividing the change in length of the material by its original length. Strain is usually plotted against the stress to create a stress-strain curve. The stress-strain curve shows the relationship between the amount of force applied to the material (stress) and the resulting deformation (strain).

Long story short, Load, elongation, and strain are critical parameters measured in a tensile test to determine the mechanical properties of a material. Understanding these parameters and their relationships can help engineers and scientists design and select materials for various applications. The load versus displacement (or load versus time) curve, elongation versus load (or elongation versus time) curve, and stress-strain curve provide valuable information about the material's behavior under tension, including its strength, ductility, and elasticity.

How does the tensile testing machine work?

Tensile testing machines, also known as universal testing machines, are used to determine the mechanical properties of materials under tension. Below is the complete standard operating procedure that explains how the machine works. Let’s have a look.

• Preparation of the test specimen: The material to be tested is first prepared into a specific shape and size according to the standard testing requirements.
• Mounting the specimen: The prepared test specimen is then placed into the grips of the tensile strength tester, with each end held firmly in place by the jaws of the grips.
• Applying a load: The machine applies a load to the specimen by moving one of the grips away from the other at a constant rate of speed. The load is usually applied in the form of a uniaxial force, which means that the force is applied in one direction only, along the longitudinal axis of the specimen.
• Measuring the load and elongation: As the load is applied to the specimen, the machine measures the amount of force applied by the load cell and the change in length of the specimen using an extensometer.
• Calculating mechanical properties: Plot the load vs. elongation curve and calculate various mechanical properties of the material, including the yield strength, ultimate tensile strength, modulus of elasticity, and ductility.
• Recording the test results: The results of the test are recorded and reported in a standardized format, along with the testing conditions and any relevant information about the specimen or testing machine.

To know more about Tensile testing machines, contact our experts at Pacorr testing instruments.