Understanding Modulus of Elasticity

04-10-2019

Modulus of Elasticity or Young’s Modulus is a description of the stiffness or elasticity of a material. It is a fundamental property that cannot be changed and is dependent on the current pressure and temperature of the sample. It is defined applied longitudinal stress divided by strain experienced by a material when it is put under lengthwise tension or compression. This defines the relationship between stress and strain in a material, representing the slope of the linear portion of a stress-strain curve.

Sourcing the correct value of the Young’s modulus of a material is important as it provides the measure of rigidness of the material, which holds a high importance in many engineering applications. In an industry where any kind of deformation due to stress is undesirable, a material possessing a high modulus of elasticity is sought, meaning a structure with high amount of rigidness is preferred. Similarly, in cases, where flexibility is required, a material possessing a low modulus of elasticity is considered. An example of material having a high Modulus of Elasticity is diamond, which changes its shape only slightly under an elastic load. A flexible material such as rubber has a low modulus of elasticity.

Commonly, materials with high Young’s modulus is required for the design of heavy parts or rigid structures such as bridges, bicycles, furniture, which only allow for tiny deflection. While designing these structures, engineers should carefully select the construction material taking into account the forces that they are going to experience in their lifetime. As an example, steel and concrete are popular choices for designing bridges. These materials are able to withstand large stress without experiencing deformation and allow reinforcement of the bridge structures to guard against any external forces.

PCB manufacturing industry is another example. Vibration almost always occurs during goods transportation. Such vibrations can fatigue the solder joints and induce permanent failures. Therefore, engineers are required to design against vibrations which involves selecting a proper material.

A list of values of the modulus of elasticity of some common materials can be found here. There are also methods to determine the value of the modulus of elasticity of your materials using either strain gauges or material testing machines. We will cover this topic in the next post.

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