Paras N. Verma, Kusumkant D. Dhote and Krothapalli P.S. Murthy
Abstract: Fragment penetration in multilayered target at hypervelocity, is a complex phenomenon and is influenced by fragment and target geometries as well as impact conditions. Authors carried out simulation studies of Tungsten Heavy Alloy (WHA) cubical fragments impacting multilayered spaced target at hypervelocity in various conditions. The target is chosen as a stack of three steel plates, which are separated by 100 mm. The first two plates are 4 mm thick and the third is 10 mm thick. The simulation models are validated by conducting two-stage gas gun trials with 9.5 mm WHA cube against the target. Using these validated models, studies are carried out to estimate the minimum size of a cubical fragment that is required to defeat the target in corner, edge and face orientations; with obliquities of 00, 150, 300 400 and 500; at 3 km/s and 5 km/s. The results are represented by a set of equations and the probability of kill given a hit is estimated for each size of fragment. The methodology is useful to optimize fragment size for neutralization of multilayered spaced targets such as ballistic missiles and spacecraft with a specified probability of kill.
Kusumkant D. Dhote, Paras N. Verma1and Krothapalli P.S. Murthy
A typical pre-fragmented warhead uses explosive energy to launch fragments. On initiation of the explosive, detonation waves impinge on the fragments and thereby generate shock waves in the fragment material. As the shock wave reaches the fragment exposed surface, the compressive stress wave is reflected back as a rarefaction wave. At the same time, the rarefaction wave generated from detonation side enters in the fragment. The interaction of these rarefaction waves induces intense tensile stresses resulting in fragment spall. Several researchers have attempted to reduce fragment spall by reducing explosive charge to fragment metal mass ratio (C/M ≤ 0.5) or by altering the explosive initiation location or by provision of shock attenuation material between explosive and fragments or by capping individual fragments. The authors have evolved an innovative solution to mitigate spall by the provision of a composite layer on the fragment exposed surface in the design of high-performance fragment generator (FG) warheads. Its performance is demonstrated experimentally in FG warhead designs having C/M ratios of 1 and 2. The soft recovered fragments in the cone angle of 300 did not show any spall in the case of fragments covered with the composite layer, whereas, the conventional design of (uncovered) fragment did spall.
T. Paul Hutchinson
Results relevant to the cushioning of impact by visco-elastic polyurethane (VEPU) and other foams were published by Saunders et al (Journal of Battlefield Technology, Vol. 15, No. 2, 2012, pp. 11-18). The present paper summarises some theory on how maximum acceleration might be affected by speed of impact, and uses it to comment on the results of Saunders et al. In the case of some foams at some speeds, it is likely that bottoming out occurred. There are several characteristics of foam deformation that potentially could be used to make bottoming out less likely: increased stiffness, nonlinear (concave downwards) response to deformation, and velocity-dependence of stiffness.
T. Andrew Au* and Edward H.S. Lo*
Ballistic missile warfare continues to present a significant threat in future conflicts due to its fast tempo and the ability to deliver weapons of mass destruction. The time for intercepting a hostile missile using ballistic missile defence is highly constrained, making workflow improvements necessary to compress the kill chain’s duration. Full-scale flight testing of realistic ballistic missile defence scenarios is difficult, if not impossible, and incurs prohibitive costs. This paper presents a process model of the missile defence sequence, consisting of searching, detecting, tracking, identifying targets, engaging, and damage assessment. The duty cycle of the task sequence executed by commanders and their staff is analysed by simulating the model to identify possible information-processing bottlenecks and overloads under different operational modes of control for battle management. We subjected the model to various tests to generate leakage rate, interceptor consumption rate, and duration as measures of effectiveness. This capability allows for “what-if” evaluations of numerous concepts for command and control or task reallocation, complementing live Exercises and experiments. Future work could incorporate human performance and missile trajectory modelling to improve simulation accuracy.
D. Vijay Rao and Dana Balas-Timar
Intelligent military training simulators offer an economic, ecologically acceptable, training platform that approximates real-life situations, and facilitate perception and interaction in a relatively unconstrained situated-learning paradigm that supports a comprehensive learning strategy. Human factors such as skills, experience, situation awareness and pilot decision-making ability in the cockpit are critical factors that determine the decision processes, course of action, and results of the simulation. Air Warfare Simulation System, a virtual warfare analysis software has been developed for planning, analysis, and evaluation of mission effectiveness in air-tasking operations where human factors play a major role in training and learning. In this paper, we propose a Neuro-fuzzy hybridization technique, Adaptive Neuro-Fuzzy Inference System (ANFIS) to model the human factors of the pilot agent and behaviour characteristics in the warfare simulator. A pilot database has been developed in order to store the specific cognitive characteristics, skills, and training experience, which affect pilot decision making. Finally, their effect on the mission effectiveness obtained by the warfare simulation has been studied. The methodology of modelling human factors of pilots using ANFIS is illustrated with suitable examples, and lessons drawn from the virtual air warfare simulator are discussed.
Bronwyn Jones, University of New South Wales, Canberra, Australia
