david felix - Academia.edu (original) (raw)
Papers by david felix
The Journal of Defense Modeling and Simulation: Applications, Methodology, Technology, 2021
Explosion models based on finite element analysis (FEA) can be used to simulate how a warhead fra... more Explosion models based on finite element analysis (FEA) can be used to simulate how a warhead fragments. However, their execution times are extensive. Active protection systems need to make very fast predictions, before a fast attacking weapon hits the target. Fast execution times are also needed in real-time simulations where the impact of many different computer models is being assessed. Hence, FEA explosion models are not appropriate for these real-time systems. As a trade-off between accuracy and execution time, this paper creates a simulation of fragments from a warhead’s explosion, using simple analytical equations. The results are verified against explosion experimental data and FEA results. The developed model then can be made available for real-time simulation and fast computation.
The Journal of Defense Modeling and Simulation: Applications, Methodology, Technology, 2021
This paper presents an improvement in the speed and accuracy of calculating the initial angle of ... more This paper presents an improvement in the speed and accuracy of calculating the initial angle of projection of fragments for exploding cylindrical shells. It is a fast tool that can be used by designers, where existing approaches, such as computationally intensive Finite Element Analysis, are preventively slow. An enhanced Taylor equation is presented using available experimental data and the effect of the changing shape of the warhead’s cylindrical casing on the fragment’s initial projection angle. The resulting equation is computationally fast as it uses uncomplicated equations and provides improved accuracy for estimating a fragment’s initial angle of projection in comparison to existing work.
Defence Technology
Explosion models based on Finite Element Analysis (FEA) can be used to simulate how a warhead fra... more Explosion models based on Finite Element Analysis (FEA) can be used to simulate how a warhead fragments. However their execution times are extensive. Active protection systems need to make very fast predictions, before a fast attacking weapon hits the target. Fast execution times are also needed in real time simulations where the impact of many different computer models is being assessed. Hence, FEA explosion models are not appropriate for these real-time systems. The research presented in this paper delivers a fast simulation model based on Mott's equation that calculates the number and weight of fragments created by an explosion. In addition, the size and shape of fragments, unavailable in Mott's equation, are calculated using photographic evidence and a distribution of a fragment's length to its width. The model also identifies the origin of fragments on the warhead's casing. The results are verified against experimental data and a fast execution time is achieved using uncomplicated simulation steps. The developed model then can be made available for real-time simulation and fast computation.
defence technology, 2019
To simulate explosion fragments, it is necessary to predict many variables such as fragment veloc... more To simulate explosion fragments, it is necessary to predict many variables such as fragment velocity, size distribution and projection angle. For active protection systems these predictions need to be made very quickly, before the weapon hits the target. Fast predictions also need to be made in real time simulations when the impact of many different computer models need to be assessed. The research presented in this paper focuses on creating a fast and accurate estimate of one of these variables-the initial fragment velocity. The Gurney equation was the first equation to calculate initial fragment velocity. This equation, sometimes with modifications, is still used today where finite element analysis or complex mathematical approaches are considered too computationally expensive. This paper enhances and improves Breech's two-dimensional Gurney equation using available empirical data and the principals of conservation of momentum and energy. The results are computationally quick, providing improved accuracy for estimating initial fragment velocity. This will allow the developed model to be available for real-time simulation and fast computation, with improved accuracy when compared to existing approaches.
journal of defense modeling and simulation, 2021
Explosion models based on finite element analysis (FEA) can be used to simulate how a warhead fra... more Explosion models based on finite element analysis (FEA) can be used to simulate how a warhead fragments. However, their execution times are extensive. Active protection systems need to make very fast predictions, before a fast attacking weapon hits the target. Fast execution times are also needed in real-time simulations where the impact of many different computer models is being assessed. Hence, FEA explosion models are not appropriate for these real-time systems. As a trade-off between accuracy and execution time, this paper creates a simulation of fragments from a warhead's explosion, using simple analytical equations. The results are verified against explosion experimental data and FEA results. The developed model then can be made available for real-time simulation and fast computation.
defence technology, 2021
Explosion models based on Finite Element Analysis (FEA) can be used to simulate how a warhead fra... more Explosion models based on Finite Element Analysis (FEA) can be used to simulate how a warhead fragments. However their execution times are extensive. Active protection systems need to make very fast predictions, before a fast attacking weapon hits the target. Fast execution times are also needed in real time simulations where the impact of many different computer models is being assessed. Hence, FEA explosion models are not appropriate for these real-time systems. The research presented in this paper delivers a fast simulation model based on Mott's equation that calculates the number and weight of fragments created by an explosion. In addition, the size and shape of fragments, unavailable in Mott's equation, are calculated using photographic evidence and a distribution of a fragment's length to its width. The model also identifies the origin of fragments on the warhead's casing. The results are verified against experimental data and a fast execution time is achieved using uncomplicated simulation steps. The developed model then can be made available for real-time simulation and fast computation.
journal of defence modeling and simulation , 2021
This paper presents an improvement in the speed and accuracy of calculating the initial angle of ... more This paper presents an improvement in the speed and accuracy of calculating the initial angle of projection of fragments for exploding cylindrical shells. It is a fast tool that can be used by designers, where existing approaches, such as compu-tationally intensive Finite Element Analysis, are preventively slow. An enhanced Taylor equation is presented using available experimental data and the effect of the changing shape of the warhead's cylindrical casing on the fragment's initial projection angle. The resulting equation is computationally fast as it uses uncomplicated equations and provides improved accuracy for estimating a fragment's initial angle of projection in comparison to existing work.
The Journal of Defense Modeling and Simulation: Applications, Methodology, Technology, 2021
Explosion models based on finite element analysis (FEA) can be used to simulate how a warhead fra... more Explosion models based on finite element analysis (FEA) can be used to simulate how a warhead fragments. However, their execution times are extensive. Active protection systems need to make very fast predictions, before a fast attacking weapon hits the target. Fast execution times are also needed in real-time simulations where the impact of many different computer models is being assessed. Hence, FEA explosion models are not appropriate for these real-time systems. As a trade-off between accuracy and execution time, this paper creates a simulation of fragments from a warhead’s explosion, using simple analytical equations. The results are verified against explosion experimental data and FEA results. The developed model then can be made available for real-time simulation and fast computation.
The Journal of Defense Modeling and Simulation: Applications, Methodology, Technology, 2021
This paper presents an improvement in the speed and accuracy of calculating the initial angle of ... more This paper presents an improvement in the speed and accuracy of calculating the initial angle of projection of fragments for exploding cylindrical shells. It is a fast tool that can be used by designers, where existing approaches, such as computationally intensive Finite Element Analysis, are preventively slow. An enhanced Taylor equation is presented using available experimental data and the effect of the changing shape of the warhead’s cylindrical casing on the fragment’s initial projection angle. The resulting equation is computationally fast as it uses uncomplicated equations and provides improved accuracy for estimating a fragment’s initial angle of projection in comparison to existing work.
Defence Technology
Explosion models based on Finite Element Analysis (FEA) can be used to simulate how a warhead fra... more Explosion models based on Finite Element Analysis (FEA) can be used to simulate how a warhead fragments. However their execution times are extensive. Active protection systems need to make very fast predictions, before a fast attacking weapon hits the target. Fast execution times are also needed in real time simulations where the impact of many different computer models is being assessed. Hence, FEA explosion models are not appropriate for these real-time systems. The research presented in this paper delivers a fast simulation model based on Mott's equation that calculates the number and weight of fragments created by an explosion. In addition, the size and shape of fragments, unavailable in Mott's equation, are calculated using photographic evidence and a distribution of a fragment's length to its width. The model also identifies the origin of fragments on the warhead's casing. The results are verified against experimental data and a fast execution time is achieved using uncomplicated simulation steps. The developed model then can be made available for real-time simulation and fast computation.
defence technology, 2019
To simulate explosion fragments, it is necessary to predict many variables such as fragment veloc... more To simulate explosion fragments, it is necessary to predict many variables such as fragment velocity, size distribution and projection angle. For active protection systems these predictions need to be made very quickly, before the weapon hits the target. Fast predictions also need to be made in real time simulations when the impact of many different computer models need to be assessed. The research presented in this paper focuses on creating a fast and accurate estimate of one of these variables-the initial fragment velocity. The Gurney equation was the first equation to calculate initial fragment velocity. This equation, sometimes with modifications, is still used today where finite element analysis or complex mathematical approaches are considered too computationally expensive. This paper enhances and improves Breech's two-dimensional Gurney equation using available empirical data and the principals of conservation of momentum and energy. The results are computationally quick, providing improved accuracy for estimating initial fragment velocity. This will allow the developed model to be available for real-time simulation and fast computation, with improved accuracy when compared to existing approaches.
journal of defense modeling and simulation, 2021
Explosion models based on finite element analysis (FEA) can be used to simulate how a warhead fra... more Explosion models based on finite element analysis (FEA) can be used to simulate how a warhead fragments. However, their execution times are extensive. Active protection systems need to make very fast predictions, before a fast attacking weapon hits the target. Fast execution times are also needed in real-time simulations where the impact of many different computer models is being assessed. Hence, FEA explosion models are not appropriate for these real-time systems. As a trade-off between accuracy and execution time, this paper creates a simulation of fragments from a warhead's explosion, using simple analytical equations. The results are verified against explosion experimental data and FEA results. The developed model then can be made available for real-time simulation and fast computation.
defence technology, 2021
Explosion models based on Finite Element Analysis (FEA) can be used to simulate how a warhead fra... more Explosion models based on Finite Element Analysis (FEA) can be used to simulate how a warhead fragments. However their execution times are extensive. Active protection systems need to make very fast predictions, before a fast attacking weapon hits the target. Fast execution times are also needed in real time simulations where the impact of many different computer models is being assessed. Hence, FEA explosion models are not appropriate for these real-time systems. The research presented in this paper delivers a fast simulation model based on Mott's equation that calculates the number and weight of fragments created by an explosion. In addition, the size and shape of fragments, unavailable in Mott's equation, are calculated using photographic evidence and a distribution of a fragment's length to its width. The model also identifies the origin of fragments on the warhead's casing. The results are verified against experimental data and a fast execution time is achieved using uncomplicated simulation steps. The developed model then can be made available for real-time simulation and fast computation.
journal of defence modeling and simulation , 2021
This paper presents an improvement in the speed and accuracy of calculating the initial angle of ... more This paper presents an improvement in the speed and accuracy of calculating the initial angle of projection of fragments for exploding cylindrical shells. It is a fast tool that can be used by designers, where existing approaches, such as compu-tationally intensive Finite Element Analysis, are preventively slow. An enhanced Taylor equation is presented using available experimental data and the effect of the changing shape of the warhead's cylindrical casing on the fragment's initial projection angle. The resulting equation is computationally fast as it uses uncomplicated equations and provides improved accuracy for estimating a fragment's initial angle of projection in comparison to existing work.