*DATABASE functionality

Hi Erick, *Database includes a bunch of information, but I'm going to assume that you are talking about the *DATABASE_ASCII_option when you look in LS-PrePost. This is where you can set what you want to output from your simulation. Here is an example of how this will look in a .k file (note that in a .k file input blocks are 10 spaces wide, it may not be correct formatting below because I'm just trying to give you a visual):

*DATABASE_RCFORC
$#    DT   BINARY    LCUR   IOOPT
       0.1           3           0           1

RCFORC stands for Resultant Interface Forces, DT is the time interval that 1 data point will be output (every 0.1 ms in this case), BINARY is an option on how the data will be written out (1 will be individual ascii files for every output, while 3 will consolidate all of the outputs into a binout which you can load once), LCUR is where you can use a *Define_Curve to determine your output frequency instead of dt, and IOOPT is a flag to determine how the LCUR curve will behave when outputting data. You generally don't need to worry about LCUR and IOOPT unless you have something specific in mind. 

There are two types of these ASCII output options: general outputs that are all encompassing and don't need further action (like RCFORC will output all contact forces in the simulation), and specific ones that require you to specify what you want to output within that category (like NODOUT which will output the nodal time history of nodes but only the ones that you specify with *DATABASE_HISTORY_NODE). I'll label some common outputs for each type:

General:

ABSTAT - Airbag statistics

BNDOUT - Boundary Condition forces and energy

GLSTAT - Global Statistics

JNTFORC- Joint Forces

MATSUM - Material Energies

RBDOUT - Rigid Body data

RCFORC - Resultant Interface Forces

RWFORC - RigidWall Forces

SLEOUT - Sliding Interface Energies

SPCFORC- SPC Reaction forces

SWFORC - Spotweld Nodal Constraint Reaction Forces

Specific:

DEFORC - Discrete Element (Need *DATABASE_HISTORY_DISCRETE)

ELOUT - Element Output Data (Need *DATABASE_HISTORY_BEAM/SHELL/SOLID or add _SET at the end)

NCFORC - Nodal Interface Forces (Need *DATABASE_HISTORY_NODE_SET)

NODOUT - Nodal Displacement/Velocity/Acceleration data (Need *DATABASE_HISTORY_NODE or _NODE_SET)

SBTOUT - Seatbelt Output data (Need *DATABASE_HISTORY_SEATBELT)

SECFORC- Cross Section Forces data (Need *DATABASE_HISTORY_SOLID_SET)

If you want to get specific output data from a set, you will have to first make the set in LS-PrePost using Model -> Create Entity. 

One last important *DATABASE card is *DATABASE_EXTENT_BINARY, specifically STRFLG. This database card has a bunch of global options for outputs. If you want to output strain or look at a heatmap of strain in the Fringe Component, you need to make sure STRFLG=1. Otherwise, you will not be able to look at any strain data. 

What if you want data outputs using NCFORC and NODOUT from two different node sets? How will you know which node set is assigned to NCFORC and which is assigned to NODOUT?

You just need to define a *DATABASE_HISTORY_NODE_SET for both sets and then you will be able to look at the NCFORC and NODOUT for both. The *DATABASE_HISTORY cards are only there to tell LS-Dyna which entities to pull data from and will then use the *DATABASE_ASCII to see what data it can extract from the histories. Think of *DATABASE_HISTORY  like the sensors, where the *DATABASE_ASCII are the switches to turn the sensors on.

Is there any way to extract force data that rigid bodies experience?