# acm (shell gap + coating)

Restriction: Available in Abaqus, LS-DYNA, Nastran, OptiStruct, and Radioss.

Creates one hexa cluster per connector and realizes a node to node connection to the linked shell meshes by adjusting it (shell coating). Different patterns are available. This is driven by the number of hexas. The appearance can be influenced via the diameter and the washer layer activation.

For LS-DYNA, the property script prop_acm_coating.tcl is used.

## ACM Realization Options

Option Action
thickness Select a thickness option used for dimensioning and positioning hexas.
shell gap
Project the hexa spot to touch the shell elements.
The position is independent from any thickness.
equival. (T1+T2)/2
Create hexa elements with RBE3 elements projecting and connecting to the surrounding shell elements.
This realization uses the shell thickness to calculate the hexa offset from the shell elements. In the case where the model is a 3T connection, the acm (equivalenced-(T1+T2)/2) realization will join the hexa elements.
detached (T1+T2)/2
Create hexa elements with RBE3 elements projecting and connecting to the surrounding shellstr elements.
This realization uses the shell thickness to calculate the hexa offset from the shell elements. In the case where the model is a 3T connection, the acm (detached-(T1+T2)/2) realization will not join the hexa elements.
mid thickness
Calculate the hexa spot size (thickness) as the air gap between the two connected parts. If there is no gap, or even a penetration, the hexa spot size will always be modeled with 1.0.
const thickness
Specify the hexa spot size (thickness).
maintain gaps
Calculate the hexa spot size (thickness) as the gap distance reduced by two times the specified value for maintain gaps.
The position is independent from any thickness.
num hexas Create a hexa cluster with 1, 4, 8, 12, 16 or 32 hexas, which are arranged in a predefined pattern.
Note: Available for all ACM realization types.
coats Define the number of hexa elements required along the thickness. Multiple solid coats are supported.
orthogonal faces Force the creation of perfectly orthogonally-shaped hexas.
Note: Available for any kind of ACM weld, if num hexas is set to 1.