Wesley Ballew

Project Background

The Naval Surface Warfare Center has directed the testing and analysis of an explosive called Deta-Sheet as Julian Davis’s Master’s Thesis project. In this test, a stainless steel cylinder, with one end ported and the other sealed, was used to absorb and show the effects of a Deta-Sheet explosion.

The analysis and modeling were done using a Finite Element model of the cylinder and modal testing of the pre-explosion cylinder. The modal information from these tests was compared to that given by the Finite Element model, such that the most accurate of the modes from the FE model could be distinguished from the lesser ones. Only the first few modes from the FE model were deemed reliable (as was expected) and only these modes were used for the analysis of the test.

For the test, a 6, 9, 13.3, and 20.4-gram charges were detonated inside the cylinder with 20 strain gages mounted in the hoop or longitudinal direction on the outer surface of the cylinder. The strain gage data for the 9-gram test, along with the FE model, was used to determine and analyze several different effects of the explosion including deformation and pressure.

For more detailed information on the experiment and Julian’s Thesis work, refer to Julian Davis’s contract – Project Background.

Project Goal

The goal of this project is to visualize the experiment. Using the strain gage data, the modal data from the FE model, and several other tools, Julian and I will make a computer-generated movie showing cylinder during the explosion and a short time afterwards.

Project Duties

Julian will be responsible for preparation of the data that will later be visualized.

1. Create a file of node numbers and locations for creation of the un-deformed cylinder.

2. Create a file of node numbers and displacements for each mode that is going to be considered in the analysis.

3. Transform the Cartesian strain data per element into cylindrical coordinates, for each mode

4. Change the format of the strain output from strain per element to strain per node, for each mode.

5. Recombine the strain data for each node and each mode into a transfer function relation of strain of the amplified mode to strain at any other node considered.

Wesley will be responsible for visualizing the prepared data.

1. For each time step, create a 3-D ANSYS model of the deformed cylinder, with a color gradient representing hoop and longitudinal strain for the desired test.

2. Using the successive JPEG images from the ANSYS models at each time step, create a movie of the deforming cylinder with a changing color gradient representing strain.