If you're familiar with 3D printing materials, you've likely come across the term "elongation at break." This parameter is commonly mentioned in product descriptions, but do you know what it actually means and how it's tested? Let me explain it to you.
Tensile Testing
Before we bring any products to market, they undergo various tests, including a tensile test. This test provides valuable information about a material's strength and ductility. It's a destructive process that determines the maximum force a material can withstand before it fails.
Key Measurements: Elongation at Break and Tensile Strength Two important measurements obtained from the tensile test are elongation at break and tensile strength.
Understanding Elongation at Break
Elongation at break is typically expressed as a percentage and represents the relative elongation at the point of fracture. It measures the ratio of the elongation at the moment of fiber rupture to the material's initial length. This parameter indicates the material's flexibility and elasticity. A higher elongation at break suggests better flexibility and elasticity, resulting in a softer feel. However, it's crucial to note that excessively high elongation at break can lead to deformation of the printed object.
Calculating Elongation at Break
When a material is subjected to tensile force, it tends to elongate. The elongation at the moment of fiber rupture, also known as the strain rate, is referred to as elongation at break (denoted as "e") and is expressed as a percentage (%). Elongation at break reflects the material's ability to undergo elongation deformation under maximum load.
The calculation for elongation at break is as follows: e = (La - L0) / L0
In this equation, e represents the elongation at break, L0 is the initial length of the material, and La is the length at which the material breaks.
Factors Influencing Elongation at Break:
1.Testing Speed: Slower testing allows the material to relax, resulting in higher elongation at break values.
2.Temperature: Generally, elongation at break increases with temperature.
3.Filler Content: The elongation at break of composite materials decreases with an increase in filler content.
Tensile Strength
Another related parameter is tensile strength, which indicates the maximum tensile stress a material can withstand before failure occurs, such as fracture or permanent deformation. When stress lower than the tensile strength is removed, the material fully or partially recovers its original shape and size. However, when the stress reaches or exceeds the tensile strength point, the material's integrity is compromised, leading to fracture.
The Case of PLA
The most widely used material in 3D printing, PLA, is derived from cornstarch and has an elongation at break of only 4%. This low value means it is prone to brittle fracture, as you might expect. If you try to bend a strip printed with regular PLA, it will easily break without any surprises.
To address this issue, we've developed PLA+ as an alternative to the brittle PLA. PLA+ offers an elongation at break of 45%, which is eleven times higher than regular PLA. This significantly reduces the likelihood of cracking and enhances durability in printed objects. As a result, PLA+ has become a popular choice for businesses using 3D printing materials, particularly prop makers and armor manufacturers, etc.
