Research of influence of different shaped charge liner materials on penetration depth using numerical simulations

Numerical simulations, using the Ansys AUTODYN program, of Panzerfaust 30 (klein) anti-tank warhead were performed to determine the influence of different liner materials on the penetration depth into a steel target. It has been shown that the choice of liner material can significantly affect the performance of the ammunition. Along with other methods of optimizing shaped charge ammunition (ie. optimization of the shape, thickness and angle of the tip of the liner, use of more potent explosive and deviator, optimization of casing thickness and stand-off distance, etc.), the use of appropriate liner material is certainly one of the most important parameters of shaped charge warheads to consider. Together with analytical calculations and experimental tests, simulations are valuable tool. Using data obtained from numerical simulations, researchers can save both time and resources during the process of munition design and optimization

Review of the estimation methods for external blast loads on structures

A review of external blast loads on structures modeling methods is presented in the paper. Also, numerical simulations of explosions in an urban scenario were done in software Ansys AUTODYN, and compared to experimental data. Recommendations were given regarding the use of numerical simulations in blast wave parameter calculations for the urban environment, as well as suggestions for further research

Trajectory estimation model for a solid body with an irregular shape undergoing extremely high aerodynamic forces

A generalized (6DOF) model for evaluating fragment trajectory elements is defined, which incorporates a novel model for estimating the projected surface of the body and novel model for estimating aerodynamic force and moment. This 6DOF model is developed on the basis of differential equations of the center of mass motion and movement around the center of mass (currently no known model incorporates movement of the body around its center of mass), and can model the parameters that play an essential role in movement of the bodies with irregular shape through the atmosphere. In our model the basic parameters (i.e. body dimensions) can be arbitrarily changed in the initial part of the analysis, and based on their values and values of initial kinematic parameters (initial velocity, position, orientation), trajectories can be determined (as well as other parameters: velocities, orientation) in a relatively short amount of time. The calculation of the complete trajectory of the fragments can be used in a number of applications: the analysis of the effects of the fragments (i.e. the safety analysis of the location of the ammunition depots, due to the potential explosion of the projectile) or in the estimation of a danger zones when demining larger quantities of the munition. Also, from the point of view of the parameters of the lethal zone of HE projectiles, it is generally important to estimate the trajectory of the fragments in the range up to 50m, so this model can be used to model such a scenario also. This model could also be potentially used wherever there is a need to calculate flight mechanics parameters of irregularly shaped bodies. Generalized (6DOF) model for estimation of an irregularly shaped body trajectory is implemented in a computer program, written in MatLab. Based on the model, the trajectory calculations were performed for the complete trajectory and for shorter distances to the center of the explosion, with varied geometric-inertial parameters and initial kinematic conditions for the given fragment

Review of methods for prediction of internal blast loading

A review of internal blast loads on structures modeling methods is presented in the paper. Also, numerical simulations of the internal explosion were done in software Ansys Autodyn. Critical areas of confined spaces were identified for this type of explosion event. Recommendations were given regarding the use of numerical simulations in blast wave parameter prediction, as well as suggestions for further research

Deformation and stress analysis of a U-shaped pipe compensator using a 3D scanner

The paper shows a comparison of the three different methods to determine stress and strain in a U-shaped pipe compensator which is used to decrease stress in long pipes due to the constrained temperature dilatations. The stress and strain are analyzed analytically first with some parts of the analytical solution obtained numerically, such as integrals with no analytical solution in a closed form, i.e., functional series can be involved as a tool to solve those integrals. The pipe is analyzed as a beam or a planar frame using the Castigliano's method to determine displacements. Since there are curved parts of the U compensator, the curved beam theory is applied. The alternative method to determine the strains and stresses along the pipe is shown using the numerical simulations in SolidWorks. The results are compared with the analytical solution. Finally, the experimental method using a 3D scanner is involved for a comparison to check the applied conditions in the analytical and the simulation model

Estimation of projected surface area of irregularly shaped fragments

The essence and the main contribution of this paper are consisted of the suggested novel method for estimation of a projected surface area of an irregularly shaped fragment, which represents a significant step toward a new method of an aerodynamic force estimation of a fragment motion through a resistive medium. The suggested method is to use a tri-axial ellipsoid that has a continuous surface (given as a mathematical function) to approximate an irregularly shaped fragment so that the fragment trajectory can be estimated faster taking into consideration that the aerodynamic force is proportional to a projected surface area of the fragment.During their motion, fragments can take any orientation relative to the velocity vector and aerodynamic force is proportional to a projected surface area of fragment perpendicular to the velocity vector, so it is necessary to have a method for correct estimation of the projected area in an arbitrary direction relatively to the fragment.The model was validated with analytical and CAD techniques, and verified using 3D model of a real fragment. The comparison of the projected surface area values for the fragment, obtained using the CAD tools and using our model, are generally in good agreement. This method represents a step toward modeling that does not require a CFD result for estimation of the aerodynamic force of irregularly shaped bodies. Keywords: Projected area, Fragments, Trajector