The research covered in this paper is related to numerical modeling of realistic threats. The final goal is to simulate the effects from the impact of an RPG-7 projectile on a GAZ-2975 Tigr infantry vehicle protected by an ERA. The fragmentation that results from the impact is studied. Leading up to the final model, several models are created, starting with an explosively driven cylinder to study fragmentation modeling. The next step was modeling the setup defined by NATO STANAG 4526 which was used to characterize the impact from an RPG-7. Based upon these results, a generic RPG-7 model was developed which impacted an ERA, modeled as two plates with a layer of high explosive (HE) between them. All models ran successfully to normal termination, and they showed how numerical tools can be used to describe and investigate these very complicated events.

The presented work documents the results of a comprehensive sensitivity study of the structural response of a military vehicle subjected to the impulse from a buried charge using the discrete particle method (DPM) to model the soil and high explosive (HE) coupled to a finite-element solver for the structure. Eighteen different process and numerical parameters were studied. Each of the numerical results was compared with a base model to see the influence of the considered parameter. The structure in the base model was the TARDEC Generic Vehicle Hull and the response parameter was chosen to be the total blast impulse (TBI) on the structure. The non-linear transient dynamic explicit finite-element solver used for the analysis was the IMPETUS Afea Solver®. The study includes soil characteristics and charge related parameters, such as size, type, geometry, and location. The depth of burial (DOB) and number of discrete particles were also considered in the study. Further, different numerical parameters were included. The results provide a good understanding of process and numerical parameters when modeling buried charges with a coupled finite-element model (FEM) and DPM approach. As a natural extension of the sensitivity study the effect of a layered soil bed is investigated, the topsoil either being dry or wet soil. Further, it is illustrated how to model a sympathetic detonation where the detonation of one improvised explosive device (IED) generates a pressure that results in the detonation of a second IED.

Metal additive manufacturing (AM), also known as metal 3D printing, is a challenging process to be controlled for desirable outcome due to its many process parameters. Residual stresses or deformations may occur in an AM manufactured part because of rapid heating and cooling cycles in the layers. The effect of process-controlled parameters in laser powder bed fusion (L-PBF) on deformations of a manufactured part has not been well examined and reported only sparely in literature. The objectives of this paper are: to study deformation behavior of a L-PBF printed part using finite element method, to perform parametric study of process input variables by changing few selected process parameters in the simulations, and to attempt identifying optimal values within the studied range of selected parameters to minimize part distortion. In this study, the material used for the heat sink finite element model was Inconel 718 which is commonly found in AM manufactured parts. ANSYS finite element program was employed to simulate a heat sink fabrication. The finished dimensions of the heat sink model were 12 mm in height, 26 mm in width, and 26 mm in depth. Thermal-mechanical sequential coupling approach was employed to simulate layer-by-layer built up process. The resulting deformations was evaluated by varying laser travel speed, base plate temperature, and initial layer angle. The maximum deformation (distortion) was observed at the corners of the heat sink model upon release from the base plate and found to be approximately 0.115 mm. Based on this study, the relative optimal simulation results for minimum distortion for selected parameters were 600 °K base plate temperature, 600 mm/sec speed of laser, and 0° initial layer angle. These results can be served as foundation for further study of varying other L-PBF process parameters.

The presented work discusses performing a V/L (Vulnerability/Lethality) analysis on an armored tank based on an RHA (Rolled Aomogeneous Armour) equivalence. It is shown how the approach works using small examples verified with hand calculations. Other more complex examples include a set of welded plates protecting a HYBRID III 50 Percentile Male ATD (Anthropomorphic Test Device). Considered response parameters are the VAA (Vulnerable Area Assessment) damage maps, expected protection capability plot, and damage area fractions. Furthermore, different V/L analyses of the Russian T-80 tank are displayed. It is illustrated how to apply the concept of explicit finite element models to find the critical RHA equivalent armor thickness at normal impact. It is done with terminal ballistic models for three materials: RHA, Aluminum 5083-H116, and Armox 500T.