Week 9-Creation of 1D Connectors Challenge

Aim: Mesh the provided model for given parameters and then connect each component by the relevant connector asked.

Target Element size - 5 Units

S.N	Quality Criteria	Value
1	Aspect Ratio	5
2	Skewness	45
3	Warping	15
4	Taper	0.5
5	Min. Length	2 Units
6	Max. Length	8 Units
7	Min angle Quad	45
8	Max angle Quad	135
9	Min angle Tria	30
10	Max angle Tria	110
10	Tria %	15

Create connector and Attach the various parts of the given model

1. Right_Rail_2 & Front_truss_1: - Seam-Quad (angled + capped + L)

2. Left_Rail_2 & Front_truss_1: - Quad elements

3. Front_truss_2, Front_truss_1 & Right_Rail_1: - Spot weld with 3 Layers and 5 mm Diameter

4. Front_truss_2, Front_truss_1 & Left_Rail_1: - Hexa (Adhesive)

5. Rear_truss_2 & Right_Rail_2: - Bolt Connector

6. Rear_truss_2 & Left_Rail_2: - Bolt Connector

7. Right_Rail_1 & Right_Rail_2: - Spot-weld with Rigid Elements

8. Left_Rail_1 & Left_Rail_2: - Spot-weld with Spring Elements

9. Rest all the component left Join them with suitable connectors

Procedure:

To start with meshing on any component we have to go through several preliminary stages, which include geometry cleanup, mid surface extraction, mid surface clean up and set up as per mesh parameters.

So, in hyper mesh, we need to first check for solids in the geometry, after import the model. And to delete the solids we will use the universal delete option and change the selection type to solids and select and delete. But when we tried to select solids in our model it selected nothing that means solids were not present in our model.

Now we need to check for any geometrical errors. This we can check by switching to wireframe mode and check for any red lines means free edges. It shows geometry is not stitched properly, because of these errors we may need to create new surfaces or stitch 2 edges together and many more possibilities are there. For our model, we found no errors.

Next, we extract the mid-surface but here we need not do it as it is a mid-surface provided to us. Now we need to check for mid-surface quality and it was in a good state. So, our next step for this model will be defeaturing as per provided quality criteria. But as this model is very straightforward, we need not defeature any region and can start meshing on it.

Now we can start with meshing area by area always start with feature capturing first and from there proceed further this way we started meshing by using option 2D - auto mesh - select surface to mesh - define mesh parameters asked - and mesh. Handling meshing in the hyper mesh is very easy as we can change the number of nodes we require on edges and generally we keep it the same on opposite edges to avoid tria formations.

Tips to have good mesh:

• Keep number on nodes same on opposite edges of an area.
• Prefer quad elements over tria.
• No trial should be there on free edges.
• No opposite tria should be there in model
• Rotating quad should not be there we can have tria in place of rotating quads if that area demands it.
• Mesh flow should be checked, which means meshing should not be in a zigzag way. It should be following straight-line paths. In curve regions, we can have flow along the curve.

This way we did meshing for this model. Also meshing should be good because if the mesh is not proper at the connection location, then it is seen that it may lead to unrealization of connection.

Now after successful completion of meshing, we need to provide connections at all relevant locations with specific connection types as asked. So to start with connections we need to go to 1D panel and there we go to connectors. Under this, we will have majorly all types of connections.

And if we want to create a beam or bar to have a specific degree of freedom at a location then we can create a cross-section using a hyper beam. Generally, connection type depends on several factors like:

• Component material properties that are being connected.
• Degree of freedom we require at that location.
• Quality of connection we require at that location, how weak it should be, or how strong it should be, and many more factor plays role in deciding connection type.

Now to start connection we should know the meaning of connection type.

Seam welding is a welding technique in which the two similar or dissimilar metals are connected by supplying an electric current and in this process a nugget formation takes place. Mostly, these nuggets are formed in the form of a butt or overlapping welding components. Nuggets are nothing but small pools of molten metal which are formed at a location with high electrical resistance. Seam welding is one of the types of resistance welding.

Spot weld is a process to join various sheet metal products, through a process in which contacting metal surface points are joined by the heat obtained from resistance to electric current, at a number of separate points.

A bolt connection can be used for end connections in tension and compression members. They can also hold down column bases in position and as a separator for purlins and beams in foundations.

The adhesive connection is a connection when two components are bonded together using an adhesive.

Now we will start with Seam Weld so for this we will go to 1D - connectors - Seam.

Here, we need to select the nodes along which we need connection, then we need to pass spacing value, which should be same as target element length ideally also we can measure the distance between nodes and give the same value. Then we tick retain nodes to retain the position of nodes while creating and realizing the connector, and then we select components to be welded. Then we give tolerance value which is very important as if we pass incorrect tolerance value our connection won't realize. Tolerance value depends on the gap between two components. All this definition decides weld location.

Then we need to select the type of seam weld we require. And define value for weld angle, cap angle, and runoff angle if necessary. All this defines weld properties.

Then the last thing, we can decide is whether we want to skip imprinting or imprint. Meaning whether we just need a connection to be made between duplicates elements at the same location and then delete duplicate elements and do connections manually at desired nodes or directly create a connection. This way actually we can keep our existing mesh to the position because while connecting out existing mesh gets disturbed and we know in some complex regions it becomes very difficult to handle mesh as per provided parameters. Also change from quad transition to remesh, and imprint to skip imprint helps in the realization of connection.

Now to know our connection is realized or not we can check by connection color. If it is green in color then it is realized, if it is yellow, it is unrealized, and if it is red then the connection failed. Correct parameter definition never leads to yellow and red color. Keeping all these factors in mind we created seam (angle + capped + L) at the asked location.

Now we will be creating a Quad type of connection which is also present in seam weld only. Now the parameters as defined in seam angle capped L same parameters were asked for quad also the difference was, we don't have a requirement here to define weld angle, cap angle, and runoff angle as the quad formation will happen here.

Next, we need to create a spot weld of 3 layers and 5mm diameter between Front_truss_2, Front_truss_1 & Right_Rail_1. For this, we need to go to 1D - connectors - spot - pass relevant parameters and realize.

Next, we need to create Hexa adhesive connection between Front_truss_2, Front_truss_1 & Left_Rail_1. For this, we need to go to 1D - Connectors - Seam - And select type as hexa adhesive - pass relevant parameters - Realize.

Here strips and coats divide the Hexa element horizontally and vertically which provides us added advantage to define different properties to each layer of elements to have multiple degrees of freedom along connection only.

Next, we need to do bolt connection at 2 locations i.e. Rear_truss_2 & Right_Rail_2 and Rear_truss_2 & Left_Rail_2. For this we need to go to 1D - Connectors - Bolt - pass relevant parameters and realize.

Next, we need to do spot-weld with Rigid Elements between Right_Rail_1 & Right_Rail_2. To do this we will go to 1D - connectors - spot - change type to rigid - pass relevant parameters and realize.

Next, we need to do a spot-weld with spring Elements between Left_Rail_1 & Left_Rail_2. To do this we will go to 1D - connectors - spot - change type to spring - pass relevant parameters and realize.

And at rest locations where we feel the connection is required, we did spot weld connection as it looked like spot connection is good for those locations.

This is to be noted that remesh was done after successful connection realization wherever needed.

Full Model with all successful connections.

Conclusion:

In this challenge, we learned about how to do 1D connections at various locations how to successfully realize them. Also, we learned a little when to use which type of connector and what all factors decide the selection of connector type. Also, we learned about which all connectors we have.