Menu

Workshops

Projects

Blogs

Careers

Hire from us


For Business / Universities

Corporate Training

Academic Up-skilling


All Courses

Choose a category

Loading...

All Courses / undefined

All Courses / undefined / undefined

logo

Loading...

FOR BUSINESSES

Corporate Upskilling

FOR Universities

Academic Training

More

Mechanical

Uploaded on

05 Sep 2022

How to Solve Tet Collapse in Tetra (Unstructured) mesh?

logo

Skill-Lync

There are two types of meshing done in Volume mesh. 

  1. Hexa Mesh
  2. Tetra mesh

Steps to Generate A Tetra Mesh:

Below are the steps to generate a tetra mesh:

  • Perform Geometry cleanup & Geometry check.
  • Give quality criteria and assign mesh length in the MESH deck. (Main quality parameters are: Min length, Max length)
  • Generate surface mesh with TRIA elements. 
  • Solve all OFF elements for the meshed surface. ( OFF elements in the case of surface mesh will be the elements that are failing for Quality criteria such as  Min length, Max length )
  • Define a Volume in the V.Mesh deck.
  • Mesh the volumes with either Tetra Rapid or Tetra FEM algorithm.
  • Solve all OFF elements for Volume meshed components with given Quality Criteria. ( OFF elements in the case of Volume mesh will be the elements that are failing for Tet Collapse).

What is A Tet Collapse?

Tet Collapse is the most important Quality criterion which is always checked while Tetra mesh is Performed (Tet Collapse is applicable to Tetra Elements only).

  • As we know the Tetra element is a four-noded element which has four sides and four nodes. (As shown in the image below)

 

  • The height of the Tetra element (h) is measured from each of the four nodes to its opposite face and then divided by the Square root of the opposite face’s area (A). The minimum of four resulting values is then normalized by dividing it by 1.24.

 

Therefore, Tet Collapse can be calculated by,

 

  • As the Tetra collapses, the value approaches 0.00. While a perfect Tetra element will have a value of 1.00  (Note: Tet collapse values less than 0.15 or 0.2 are not acceptable.)

So, If the height of the tetra element is less than the desired height then that element will fail for Tet Collapse.

How to Solve A Tet Collapse?

Method -1: Using ‘Fix Quality’ (Auto-Correction):

  • For this, Isolate the failed elements and do Neighbour 1st level. (By doing Neighbour 1st level we can see the neighbour elements which are connected with isolated elements)
  • Click on Fix Quality to solve the failed elements. (Refer to the below image to find out the Fix Quality tool)

  • By doing this, ANSA will apply some small nodal movements which will eventually increase the height of the Tetra elements and failed elements will be solved automatically.
  • But, this step may move the nodes outside the surface and create raised edges or kinks on the surface (i.e Node can move outside the surface or inside the surface) which will reduce the surface quality.

Method -2: Through MV Free (Manual Correction):

This is the method of solving Tet Collapse without disturbing the surface quality. 

  • For this, isolate the failed elements and do Neighbour 1st level. (By doing Neighbour 1st level we can see the neighbour elements which are connected with isolated elements)
  • Click on MV Free and select a Node which can be moved such that the height of the Tetra element can be increased. (Refer to the below image to find out the MV Free tool)

 

  • Drag the node in the direction of height till it obtains the acceptable height of the element.
  • Care should be taken while selecting the node for the movement. The node which is on the surface should not be moved in order to solve the failed element.

Hints:

While performing Volume mesh(Tetra mesh), a few things should be checked properly.

  1. Geometry should be closed. (i.e. Geometry should not have any Single Cons)
  2. Surface Mesh elements must satisfy quality criteria parameters. (i.e. Min length, Max length)
  3. Volume mesh elements must satisfy quality criteria (i.e. Tet Collapse) without sacrificing the surface quality of the component.

Author

author

Navin Baskar


Author

blogdetails

Skill-Lync

img

Continue Reading

Related Blogs

Shock tube simulation

Learn how to render a shock-tube-simulation and how to work on similar projects after enrolling into anyone of Skill-Lync's CAE courses.

Mechanical

10 May 2020


What is Finite element analysis (FEA)?

What exactly is Finite element analysis? How would one explain the basic concept to an undergrad friend? Learn how FEA courses at Skill-Lync can help you get employed.

Mechanical

08 May 2020


Design of Frontal BIW enclosure of a car (Bonnet)

In this blog, read how to design the frontal BIW enclosure of a car (Bonnet) and learn how Skill-Lync Master's Program in Automotive Design using CATIA V5 will help you get employed as a design engineer.

Mechanical

10 May 2020


What is Tetra Meshing?

Tetrahedral is a four- nodded solid element that can be generated through the tria element by creating a volume and also through the existing volume of the geometry. These elements are used where the geometry has high thickness and complexity. The image attached below is a representation of a Tetra element. The Tetra element will have 4 triangular faces with four nodes joining them together

Mechanical

02 Aug 2022


Realizing Connectors In HyperMesh

A connector is a mechanism that specifies how an object (vertex, edge, or face) is connected to another object or the ground. By often simulating the desired behaviour without having to build the precise shape or specify contact circumstances, connectors make modeling simpler.

Mechanical

03 Aug 2022



Author

blogdetails

Skill-Lync

img

Continue Reading

Related Blogs

Shock tube simulation

Learn how to render a shock-tube-simulation and how to work on similar projects after enrolling into anyone of Skill-Lync's CAE courses.

Mechanical

10 May 2020


What is Finite element analysis (FEA)?

What exactly is Finite element analysis? How would one explain the basic concept to an undergrad friend? Learn how FEA courses at Skill-Lync can help you get employed.

Mechanical

08 May 2020


Design of Frontal BIW enclosure of a car (Bonnet)

In this blog, read how to design the frontal BIW enclosure of a car (Bonnet) and learn how Skill-Lync Master's Program in Automotive Design using CATIA V5 will help you get employed as a design engineer.

Mechanical

10 May 2020


What is Tetra Meshing?

Tetrahedral is a four- nodded solid element that can be generated through the tria element by creating a volume and also through the existing volume of the geometry. These elements are used where the geometry has high thickness and complexity. The image attached below is a representation of a Tetra element. The Tetra element will have 4 triangular faces with four nodes joining them together

Mechanical

02 Aug 2022


Realizing Connectors In HyperMesh

A connector is a mechanism that specifies how an object (vertex, edge, or face) is connected to another object or the ground. By often simulating the desired behaviour without having to build the precise shape or specify contact circumstances, connectors make modeling simpler.

Mechanical

03 Aug 2022


Related Courses

https://d28ljev2bhqcfz.cloudfront.net/maincourse/thumb/masters-cfd_1636550988.jpg
Post Graduate Program in Computational Fluid Dynamics
4.8
135 Hours of content
Cfd Domain
Know more
https://d28ljev2bhqcfz.cloudfront.net/maincourse/thumb/combustion-cfd-specialisation_1636553169.png
4.8
35 Hours of content
Cfd Domain
https://d28ljev2bhqcfz.cloudfront.net/maincourse/thumb/flow-simulation-solidworks_1612265422.jpg
4.7
2 Hours of content
Cfd Domain
//edxengine-live-courses-files.s3.amazonaws.com/1508988009.pngRecently launched
18 Hours of content
Cfd Domain
https://d28ljev2bhqcfz.cloudfront.net/maincourse/thumb/flow-simulation-solidworks_1612265422.jpg
4.7
2 Hours of content
Cfd Domain
https://skill-lync-portal.nyc3.digitaloceanspaces.com/maincourse/thumb/15942014608.png
4.3
2 Hours of content
Cfd Domain
https://d28ljev2bhqcfz.cloudfront.net/mainproject/thumb/pedestrain-head-impact-simulation-using-ls-dyna_1616574080.jpgRecently launched
0 Hours of content
Cfd Domain
https://d28ljev2bhqcfz.cloudfront.net/mainproject/thumb/flow-over-mbactros-truck_1616159835.jpgRecently launched
0 Hours of content
Cfd Domain
Showing 1 of 18 courses
Try our top engineering courses, projects & workshops today!Book a FREE Demo