## 2 Numerical Modeling I  
A series of computer simulations is run to identify a general trend of damage and other related behaviors on the surface of a mild steel target under the impact of a LSC jet.  
By studying the parameters of the linear shaped charge jet impact onto the target surface, including the penetration depth, several effects can be studied. Firstly, the overall extent of the damage profile generated from the LSC jet impact after flight of a certain standoff distance can be more effectively analyzed. The accuracy of the simulation parameters can also be examined allowing a further detailed investigation later by comparing the simulation results to the actual testing results and the numerical parameters can be re-adjusted to improve the accuracy of the simulation results. Because of the identification of the damage profile on the surface of the mild steel target and the flight pattern of the jetting is more important than the study of jet formation after the liner collapse in this section, the investigation focuses on the damage profile after the impact and jetting pattern during flight. The computer simulation software used during this analysis is AUTODYN(r).  
In order to investigate the jet penetration formation into a mild steel target, a commercially manufactured 1,200 gr/ft LSC and a mild steel target are modeled and simulated. The 1,200 gr/ft LSC is created based on the manufacturer specifications for accuracy. The LSC and target are built using the SPH and Lagrangian solvers [6] respectively totaling 2.7 million cells in a single model.  
The LSC and target are set to maintain the optimum standoff distance (OSD) between the LSC base and the target surface as described by the manufacturer. The material properties of the models can be  
The OSD model is created in order to validate the penetration depth into the mild steel target. It is then compared to the penetration profile created in a target from previous experimental data. This is a vital model in the validation of the model set-up since there are several comparable data sets available and the outcome of the shot is well-known. For this model the LSC is detonated with a plane wave at 0.75 inches (1.905 cm, OSD) above the target. The front and side profiles of the penetration can be seen in Figures 2, 3 and 4.  
The penetration depth from the simulation result was around 20.32 mm at the deepest point, and the testing result shows around 26.2 mm. The penetration depth is not exactly matching in two cases, but the jet remnant over the penetration in Figure 2 may create more penetration afterward getting close to the testing result. In general, the jet entrance width on the surface of the target, skewed jet marks near the main penetration and penetration profile inside the target are almost identical to the experimental results. From the figures above, the model is able to validate the level of accuracy of the template for further investigation.  
Figure 4: Top view of target at OSD (left: simulation result, right: a general testing result).  
Figure 3: A general cutting formation (a mild steel target was dissected to reveal the penetration profile).  
Figure 2: Simulation results (front and side view of penetration profile at optimum standoff distance (OSD)).