The Span Merge component captures the merging of multiple webs from a Node Webs Merge component and the exit configuration for the merged web.

A Span component must be connected to rollers, drums, sources, or sinks from the Web Handling Library.

A Span Merge components is only used with one of the Merge Node components (2, 3 or 4 Nodes). The component requires the definition of the number of the ingoing webs and the reference for the web properties.

Example:

The equation base is comparable with a MultiWebRollerOut component without considering the nip rollers. Consider a portion of the web between two boundaries a and b (i.e. a control volume). Assume the web velocity goes through a discontinuous change at the left (entry) boundary which is at the node location.

The conservation of mass for the control volume can be expressed as

Based on the above assumption we can write

where $L\=x_b-x_a$ and we dropped $t$ to simplify the notation.

The mass of an infinitesimal length of the web is

where subscript $u$  is for the undeformed state.

The element strain in the Machine Direction (MD) can be written as:

Putting (3) and (4) together, we get:

Substituting (5) into (2) and simplifying yields:

What remains is the material's constitutive equation. Assuming linear visco-elastic material (Kelvin–Voigt model), we have, for $i\=1..n$:

Summary variables provide easy access to quantities that maybe important in simulations to measure performance and other key metrics.

[1] Units are set in the corresponding Web Properties block (under the Summary variables section).