Mass report in D3HSP file

Considering one single 4 noded shell element with mass equal to vol * density = 2*2*2*0.07 = 0.56.
From this it follows that each node has a mass of 0.56/4 = 0.14.

In addition, there are two lumped masses defined via *element_mass:
at node 2, lumped mass = 0.10
at node 3, lumped mass = 0.20

This means that:
node 1: 0.14 (nodal structual mass)
node 2: 0.14 + 0.10 = 0.24 (nodal structual + lumped mass)
node 3: 0.14 + 0.20 = 0.34 (nodal structual + lumped mass)
node 4: 0.14 (nodal structual mass)

Furthermore, Nodes 1 and 3 are included in a nodal rigid body via *constrained_nodal_rigid_body.

Within D3HSP file one can find the following messages:

```"total mass of body          =0.86" and "t o t a l  m a s s          = 0.86"
```
• total mass is 0.56 + 0.10 + 0.20 = 0.86 (structual + lumped mass = total mass)
`"total mass of lumped masses = 0.30"`
`"mass of nodal rigid body    = 0.48"`
• mass of NRB = 2*0.14 + 0.20 = 0.48  (nodal structual + lumped mass)
```"m a s s   p r o p e r t i e s   o f   p a r t #       1
total mass of part          = 0.28"```
• This is the mass of the shell material NOT included in the nodal rigid body (total mass - mass of nodal rigid body).

"summary of mass" section,

```"lumped mass in deformable
part of structure      mass= 0.10".```
• This is the lumped mass at node 2. The lumped mass at node 3 is included in the nodal rigid body and thus is not in the deformable part of the structure.
`"part id   =        1   mass= 0.56 mass in rigid body= 0.28"`
• The first number is the shell material mass (structual mass); the second number is the portion of that mass included in the nodal rigid body. No contribution of lumped masses is included on this line.
```"nodal rigid body ID      100  mass= 0.48"

"total nodal rigid body mass= 0.48"```