## General Mechanical

#### Why are linear elements better at handling high distortions than quadratic elem?

• helen.durand
Subscriber

Hello, I am running transient structural simulations and have been comparing linear versus quadratic elements.

According to "How to Handle Element Distortion Errors in Hyperelastic Materials — Lesson 3"  (Located at https://courses.ansys.com/index.php/courses/topics-in-hyperelasticity-using-ansys-mechanical/lessons/how-to-handle-element-distortion-errors-in-hyperelastic-materials-lesson-3/ or alternately at https://www.youtube.com/watch?v=fI2a_xP0veI): "Linear elements are a better choice in this case as they can experience more distortion before becoming so highly distorted that they can no longer be mathematically valid for the solution"

Why can linear elements handle more distortion than quadratic elements?

Thank you!

• Bill Bulat
Ansys Employee

Hi Helen,

Quadratic elements have midside nodes, linear elements do not. When quadratic elements become severely distorted, sometimes the displaced location(s) of the midside nodes introduce sharp bends in the element edges on which they reside, or they may pass through the domain of the element and penetrate a face on the opposite side of that element. A linear mesh is often less susceptible to "mesh entanglement" than a quadratic one because linear elements do not have the midside nodes that are at times responsible for excessive element distortion.

Kind regards,

Bill