Institute: Systems Realization Laboratory, Woodruff School of Mechanical Engineering, Georgia Tech
Advisor: Dr. Janet Allen, Dr. Farrokh Mistree
Team: The team consisted of 2 professors/advisors, 2 PhD students focusing on design optimization studies, and me (Gary Puri). My primary task was creating the finite element models, parameterizing them with Python scripts, and setting up a ModelCenter workflow to run the optimization studies.
Briefly:
- Created computer models of honeycomb core sandwich structures and tested their response to high explosives using Abaqus/Explicit in order to find optimum structural and material configurations
- Compared theoretical predictions to numerical models previously generated by the lab
- Spent over 150 hours writing scripts for Abaqus in the Python programming language in order to automate simulations.
- Designed software interface in ModelCenter to run simulations and graph results.
- The research was conducted at the request of the Army Research Laboratory to produce blast resistant panels that can withstand landmine explosions.
- Published results
Details:
This work into blast resistant panels (BRPs) arose from a problem posed by the Army Research Laboratory through the participation of the Georgia Tech’s Systems Realization Laboratory in the Penn State – Georgia Tech I/UCRC for Computational Materials Design. There were a few different goals here.
- Design and efficiently analyze different BRP configurations
- Design a BRP concurrently with the material and design process
The first goal is self explanatory, and this was a primary task in this research. The second goal originated from a study of how to manage complexities in a design process - such as the integration of product design and material design - by a student on the team pursuing his PhD in Optimization studies. Design embodiment is the design phase which takes a product from the conceptual stage to the detail design stage. The design and analysis of the BRP was considered a good example for such a study on making design decisions.
Our work culminated in a paper "Designing Embodiment Design Processes for Blast Resistant Panels" which is available here.
Blast resistant panels are specially designed structures that can dissipate the forces generated by an explosion by plastic deformation.They absorb large amounts of energy through core crushing. They deflect less under the same impulse loading than a solid plate of equal mass. They are thus used as protective armor on military vehicles such as on the underside of a tank, to offer protection from landmines.
High explosives on detonation spontaneously release large amounts of heat and cause large changes in pressure due to the high rate of energy release. Explosive force is released in a direction perpendicular to the surface of the explosive. The impacting forces are expected to be unevenly distributed over the surface, and vary depending on the radial distance of each point on the surface of the BRP from the explosive. In addition, it is necessary to consider the fact that the impact of the blast will not be felt over the entire BRP surface at the same time. Abaqus/Explicit was used to perform the analysis.
The BRP design used was that of a sandwich structure, consisting of two flat outer plates with a square honeycomb structure in the middle.
Only 1/4 of the BRP was modeled taking advantage of symmetry conditions to save on computational cost. Abaqus/Explicit was used for the analysis to account for the intertial effects of the impulsive explosion load. The core crushing is evident from the following figures.
Since the study involved changing the dinensions and material properties of the above model, a fully parameterized Python script was written to automate the task in Abaqus. This script created the geometry based on dimensions provided as input variables. It then assembled the parts, applied the loads and boundary conditions, and ran the analysis, all without any further user intervention.
The script was then linked to ModelCenter from which the variables could be changed and the script initiated. The material plasticity data and teh load amplitude vs time data were stored in separate spreadsheets, and wrappers were created to extract this data from these spreadsheets and introduce them into the script. The Python script was also modified to perform post processing tasks and export relevant information to a results spreadsheet.
The ModelCenter workflow setup is displayed in the following figures.
This model was then integrated into the embodiment design study which was later published.
After this research was completed and the results published, I began work on my book Python Scripts for Abaqus - Learn by Example (external website: www.AbaqusPython.com)
Provided by Gary Puri (www.gautampuri.com)
