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# Introduction

A brief description of the example.
```ONTACT_TIED_NODES_TO_SURFACE
Discrete Nodes Tied to a Surface
CONTACT_NODES_TO_SURFACE
Rigid Sphere Impacts a Plate at High Speed
LS-DYNA Manual Section: *CONTACT_NODES_TO_SURFACE

*CONSTRAINED_TIED_NODES_FAILURE

Example: Rigid Sphere Impacts a Plate at High Speed

Filename: contact.n2s-sphere.k

Description:
A sphere impacts a plate at high speed causing failure of the plate.
This model can be used to show how different contacts can behave differently
in a rather simple model. Instructions of this are explained in the header
of the input deck.

Model:
A rigid sphere is made out of solid elements and given an initial velocity of
89 mm/ms towards a plate using the *DEF INE_BOX ke yword. The plate is
constructed out of shell elements. The shells of the plates do NOT have their
nodes merged at common locations. Instead, tied nodes with failure constraints
are used to connect the common nodes. This allows the plate to rupture and
rip along seam lines instead of having elements fail (and being deleted) by
using the more common failure criteria within the material definition.

Results:
The plate is definitely not made out of a bullet proof material.
Example: Discrete Nodes Tied to a Surface

Filename: contact.tied_nodes.box.k

Description:
A shell element drops onto and then rebounds from, a hollow box that is tied
to an elastic plate.

Model:
The plate measures 40 * 40 * 1 mm3 and contains 16 Belytschko-Tsay shell
elements. The dropped shell element has a side length of 10 mm, a thickness
of 2 mm and a drop height of 10 mm. The box contains 12 Belytschko-Tsay shell
elements. All shell element materials are elastic. The initial velocity of the
shell elements is 100,000 mm/second. The calculation terminates at
0.002 seconds.

Input:
The nodes of the dropped shell are given an initial velocity
(*INITIAL_VELOCITY). The nodes on the bottom of the box, those facing the plate,
are tied to the plate (*CONTACT_TIED_NODES_TO_SURFACE). Automatic single
surface contact is used to define the contact between the dropped shell and
the box.

Reference:
Schweizerhof, K. and Weimar, K.```