What is a tensile test?

A tensile test is essential and helpful to understand the properties of different types of materials, and how they react under a load. Mechanical properties of materials are of utmost importance for engineers when it comes to structure design, determine the causes of material failure, and calculate maximum loads on certain materials, because they determine whether a material is safe under certain conditions. Most of the times, people don’t think about the importance of studying materials, and it is involved almost everywhere, for example, roads, bridges, buildings, etc. This post will demonstrate the importance of the study of materials and why engineers study it.

The analysis of structures requires the knowledge of properties, such as Young’s modulus, yield strength, ultimate tensile strength, and fracture stress. Engineers have to be aware of these properties and the differences between materials to achieve a safe design. Young's modulus is a property that describes how stiff a material is, and is calculated by dividing the stress of a material (force per unit area) by its strain (relative change in length). Once the stress and strain data from the test are known, then the results can be plotted to produce a curve called the stress–strain diagram. This diagram is very useful since it applies to a specimen of the material made of any size.

The image above is a plot of experimental stress vs strain of 6 different materials: 304 stainless steel, 2024 aluminum, 360 brass, 1018 steel, 1045 steel, and acrylic. This experiment was performed using a MTS universal testing frame. To obtain the Young's modulus, one would have to calculate the slope of the curve at the elastic region. The steeper the slope is, the higher Young's modulus is obtained, and the more brittle the material is.

Hopefully, you gained some understanding of this subject. Please promote this post and feel free to comment!