Alyaa E. By Alyaa E. • November 29, 2018

Material Properties 101: Material Selection based on Properties

What is the best material for 3D printing? Is it ABS, PA12, PLA, IN718 or AlSi10Mg? Every additively manufactured part is different. It all depends on the individual material properties as it relates to the production output goals.

Material properties including tensile strength, tensile modulus, elongation at break, flexural strength, flexural modulus and density all help define and categorize materials. These properties are crucial for choosing the most ideal material for 3D printing. In this article, we’ll focus on each characteristic as it relates to additive manufacturing.

 

Tensile Strength  The tensile strength of a material is the maximum amount of tensile stress that it can be subjected to before failure. The definition of failure can vary according to material type and design methodology.

Link3D ultimate-tensile-strength

Figure 1  Stress Vs. Strain - Visual from ADMET
 

Ultimate tensile strength  is a measurement of the force required to pull something such as rope, wire, or a structural beam to the point where it breaks. The tensile strength of a material is the maximum amount of tensile stress that it can take before failure, for example breaking.

Tensile Modulus  is a mechanical property that measures the stiffness of a solid material. It defines the relationship between stress and strain in a material in the linear elasticity regime of a uniaxial deformation, or  slope of its stress–strain curve in the elastic deformation region. A stiffer material will have a higher elastic modulus.

Elongation at Break  also known as fracture strain or tensile elongation at break, is the ratio between increased length and initial length after breakage of the tested specimen at a controlled temperature. It is related to the ability of a plastic specimen to resist changes of shape without cracking.

Link3D Young's modulus Test

Figure 2  Fracture graph for Tensile Modulus - Visual from ADMET

Flexural Strength  The most common purpose of a flexure test is to measure flexural strength and flexural modulus. Flexural strength is defined as the maximum stress at the outermost fiber on either the compression or tension side of the specimen. Flexural modulus is calculated from the slope of the stress vs. strain deflection curve.


Link3D - Universal-testing-machine-for-Three-point-flexural-strength-test

Figure 3  Three point Flexure Test - Visual from SubsTech

Flexural modulus  or bending modulus is an intensive property that is computed as the ratio of stress to strain in flexural deformation, or the tendency for a material to resist bending. It is determined from the slope of a stress-strain curve produced by a flexural test (see image above for example of flexural test).

Density  Since mass is usually expressed in grams and volume in cubic centimeters, density is expressed in grams/cubic centimeter. We can calculate density using the formula: Density= Mass/Volume. Density is the mass contained within a unit volume.

All of these material properties can be used to define and categorize a material. Polymer materials tend to have a lower tensile modulus as compared to metals. Using Link3D Additive MES’s Material Recommendation System, users can customize their search using the properties in order to find the most suitable material for their 3D printing needs.

Link3D users can also identify some key characteristics about the material they need i.e: stiff, strong, or biocompatible which can help narrow down the search for the most suitable material for them.

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