WeldFEM detects two basic types of modelled welds: weld as direct node connection and weld as rigid-connection.

While node to node connections by rigid-elements are always considered as possible welds, WeldFEM considers connections by common nodes at element edges in case a) the property ID changes or b) the angles between two plate-elements is approximately rectangular..

Note:        A weld that is modelled by using the Glue command in Femap will not be detected by WeldFEM.

Weld As Direct Node Connection

In Femap a direct node connection is created by merging two nodes.

Some examples of direct node connections are given below, the red line indicates the location of the weld.

Tee Joint

Corner Joint

Butt and Skew Joint

Weld As Rigid Connection

In Femap a rigid connection is created by establishing a link between two nodes with a rigid-link-element (RBE2-element).

Some examples of rigid connections are given below, the red line indicates the location of the weld on each side of the plate.

Tee and Butt Joint

Overlapped Joint

Skew Joint

In some cases, multiple weld joints are close together, so that they are only separated by one PLATE-element in the corresponding FE-model. Since these elements have one RBE2-element per node, WeldFEM can no longer correctly detect welds in the FE-model. In this case, WeldFEM would detect welds as shown in the picture below. The cyan and orange highlighted edges are welds, which exist and are part of the design. The red highlighted welds are incorrectly found welds by WeldFEM, they do not exist.

In order to get around this issue, WeldFEM is also able to distinguish welds by the colour of the used RBE2-elements. Therefore assigning different colours to specific welds is not necessary but helpful in situations as depicted above. The adjusted FE-model, where RBE2-elements are coloured according to the welds, is depicted below. It is important to note, RBE2-elements modelling one joint should have the same colour. Otherwise two different welds will be detected, where there is only one.

Specifics Of Modelling Butt Joints

A butt joint is a specific weld connection type. In order for WeldFEM to detect butt joints they need to be modelled in a certain way.

Hence it is necessary to make use of two different properties, since there are no other indicators for a weld at the junction itself.

Specifics Of Modelling Plate-Solid-Connections

An automatic weld detection between PLATE- and SOLID-elements, just like shown below, is not yet supported. No matter if the connection is direct or per RBE2-element.

Intended corner joint

Intended tee joint

Intended butt joint

Welds that are intended to be between plate- and solid-elements need to be modelled in a certain way, so that WeldFEM is able to detect those.

Along the weld, the plate elements need to be extended by one row of elements in the direction of the solid-elements. Each PLATE-element of this new row is congruently with its adjacent solid-element area. Nodes of PLATE- and SOLID-elements must be merged. The plate to solid connection has now additionally become a plate to plate connection, which can be now detected by WeldFEM.

Intended corner joint

Intended tee joint

Intended butt joint

The additional row of plate-elements needs to be off a new plate property, since the new plate to plate connection is technically a butt joint.

WeldFEM would detect a butt joint in every single case. In order to change the joint type a special coding notation has been implemented, which will be described in When And Why To Use Coding Notation.

Modelling Welds Not As Recommended

In case welds are not modelled WeldFEM compliant, it might not detect the hole weld correctly. Therefore WeldFEM is only able to plot results at locations where a weld has been detected, just like shown below. For this reason we advise to follow the meshing instructions as described above.