I am looking to use Patran to model an explosive-structural interaction. I have read the Nastran documentation on Basic Blast analysis which does a nice job of covering the theory behind the analysis, but can not find any material to demonstrate how I could replicate this example. More specifically, how the detonated material is modeled as a sphere of gas with internal energy. I am not sure how they went about modeling a gaseous material and applying the energy using hex elements as the only geometry, and how they differentiated between the explosive material and the surrounding environment. Any help is greatly appreciated.
Thank you!
Edit: This is how far I have gotten recreating this in Patran:
- Create a new db in Patran
- Analysis type Explicit Nonlinear
- Create .5 by .5 by .5 solid cube with one corner at the origin
- Mesh it with Hex8 elements 20 elements across each direction
- Create 3D Euler Solid property - apply it to the solid cube
- Option: PEULER 1
- Create Load/BC: Init. Cond. Euler Element Uniform
- Option: Shape -New Set Name: Explosive - Input sphere radius .05 centroid coord 0
- Option: Initial Values - New Set Name: Explosive1 - Density: 7.74 specific internal energy: 1.29E10
- Option: Shape -New Set Name: Air- Input sphere radius .5 centroid coord 0
- Option: Initial Values - New Set Name: Air1 - Density: 1.29 specific internal energy: 1.938E5
- Option: Region Definition- input data - explosive shape/explosive 1 init value/level 1 - add row - air shape/air1 init value/ level 2 - add row
- Analysis - solution type - solution parameters - solution700 parameters - execution control parameters - initial time step size: 1.5E-7 - minimum time step: 1.5E-8
- Results output format: xdb
- Submit for analysis
No xdb is created for review or postprocessing. I have noticed that example .dat file defines INISTEP where the method I use in Patran defines DYMINSTEP which I can not find any documentation for. This is prompted as a message in the Error file. Also, error file contains:
INPUT DECK: blast_basics.dytr.dat
LINE #4 : SUBTITLE,DEFAULT
MESSAGE : Unknown Case Control keyword - SUBTITLE
