ALBAS : An Integrated Software for Carrying Out Parametric Vulnerability / Lethality PLEIADES / A Calculations

ALBAS is an integrated software which enables to set, to run, to manage simulations done with the computerised endgame code PLEIADES/A 2 which is the DGA modular software suited for vulnerability studies of air systems (aircraft, hel icopter, UAV,…) attacked by conventional weapons and anti-aircraft weapons lethality assessment. Via the ALBAS Graphical Users Interface (GUI), para metric PLEIADES/A calculations can be runned. Selected parameters refer to target, threat , d mage mechanisms and terminal effects and engagement geometry. ALBAS engagement scenarios increase in value concer n possibility to select burst points grid, burst points cloud, burst points at different miss distan ce and shot line. ALBAS offers possibilities to tak e into account uncertainties of parameters (i.e. burs t point on a given shot line and miss distance) by applying a random choice of them according Monte-Ca rlo methods. Kill Probability (Pk values) in this probabilistic approach are done in terms of standar d deviations around average values. Computing can be divided in sub-computing which are submitted each of one to one processor of the CEG ATLAS supercomputer. Concerning output computing, ALBAS offers capabilit ies of treatment of fully results Excel tables. Statistical analysis can be conducted. In conclusion, ALBAS which is based on PLEIADES/A a lgorithms, offers large capabilities for carrying out parametric computing using the entire CPU of the CEG supercomputer. 1.0 INTRODUCTION As indicated above, ALBAS is based on PLEIADES/A al gorithms. That’s why, the first step of the paper is to remind some general remarks about P LEIADES/A : its current capabilities and its current studies conducted to improve the code. Thes e improvements concern specifically damage mechanisms and terminal effects topics. The second step of this paper consists in a detailed presentation of ALBAS, the integrated software. Fin ally, bonus capabilities offered using ALBAS post processing are detailed. 1 ALBAS : Atelier Logiciel de Bombardement d’Aéronef au Sol 2 PLEIADES/A : Produit Logiciel d’Etude des I nfrastructures et des A éronefs et de D étermination de l’Endommagement de leurs Systèmes/Aéronefs RTO-MP-AVT-153 10 1 UNCLASSIFIED/UNLIMITED UNCLASSIFIED/UNLIMITED ALBAS: An Integrated Software for Carrying Out Parametric Vulnerability /Lethality PLEIADES/A Calculations 2.0 OVERVIEW OF THE PLEIADES/A SOFTWARE ([1], [2], [3]) The Centre d’Etudes de Gramat (CEG) is the French D efence Procurement Agency (DGA establishment, in charge of developing and linking software devoted either to the anti-air or anti missile warfare assessment. PLEIADES/A is a modular software suited for vulnera bility studies of aircraft attacked by conventional weapons or anti-aircraft weapons letha ity ssessment. 2.1 Methodology to evaluate the vulnerability of an aircraft submitted to a conventional threat (Figures 1, 2) A probabilistic methodology is employed to evaluate th air vehicle vulnerability; this methodology is based on models of: • the engagement geometry, the threat against which t e vulnerability of the weapon system must be evaluated, the target and the effects of th e threat on the traget. With this information, influence of degradation of the functioning on comp nent level is used to determine the functioning of the complete target by using a so-ca lled fault tree analysis. Threat and target basic models, vulnerability data and fault trees are obtained by using • numerical simulations using full physics codes (nam ely Ouranos and/or Abaqus) to understand physical phenomena by reaching specific parameters not available through trials, • physical experiments conducted on small-scaled targ e s (sample, structure model) or decommissioned target (specifically aircraft). 2.1.1 Engagement geometry The encounter conditions describe how the warhead i ntercepts the target: threat location and orientation with regards to the target, target and threat speed vectors. 2.1.2 Threat Threats taken into consideration are bullets, fragm entation warheads and KE ammunitions. Direct hit may also be achieved by taking into account missile body. Warhead models data are number of fragments, mass, ejection angle, ejection velocity, material and fragments position tables 2.1.3 Targets Targets are fighters, transportation aircrafts, hel icopters, UAV, missiles and land base radars. Targe t model consists of : • a geometry including components whose damage or los s c uld lead to the target kill, a physical properties tables used for perforation com putations (thickness, name and nature of materials, • vulnerability data (destruction criteria tables) re presenting kill probability of an equipment given a threat. With the knowledge of effects of th e t reat on target (ie an aircraft), the influence of the degradation of the functioning on component level is used to determine the ALBAS: An Integrated Software for Carrying Out Parametric Vulnerability /Lethality PLEIADES/A Calculations 10 2 RTO-MP-AVT-153 UNCLASSIFIED/UNLIMITED UNCLASSIFIED/UNLIMITED functioning of the complete target by using the fau lt-tree analysis (FTA). 2.1.4 Damage mechanisms and terminal effects Two mechanisms are taken into account : • blast loading : depending on the warhead and fusing , the blast may be external or internal to the target (ie an aircraft), • fragment kill mechanisms : damage inflicted on targ et depends on number and location of fragments impacts and on terminal effects parameter s. Fragment kill mechanisms are function of target and fragments types, they are defined as follows o functional damage : a fragment may lead to the comp onent function loss or degradation (ie tank leakage or control rod cut), o incendiary effects : vapours of kerosene are sensit ive to the impact of a bullet or a fragment spray on a fuel tank ullage. An explosion of the fuel air mixture can occur, an overpressure could lead to a tank rupture, could damage surrounding structure and conduct to complete aircraft disintegration, o hydrodynamic Ram : HRAM is the development in a flu id, of shock waves caused by a ballistic penetrator (bullet, fragment,…). o synergistic effect of fragments : this effect happe ns when a large number of fragments impact at the same time a small area. A damage cri terion CS defined experimentally is a function of fragment kinetic energy E and the are a size S that was struck. 2.1.5. Fighter vulnerability assessment Vulnerability of an aircraft to an externally deton ati g warhead is usually analysed in two separate steps. One step is a determination of the aircraft structural vulnerability to the synergetic effects of blast and fragment spray and the second one examine s a rcraft’s functional vulnerability to effects of a unitary fragments. 2.2 PLEIADES/A outputs The PLEIADES/A modular software gives for an aircra ft t rget, the following outputs: • Projectile flight and path through the target (incl uding velocity decay as a function of drag and presented area), projectile velocity and mass decay while perforating the target, • Components of air target probability of kill from i pact, • Multiple hit synergetic effect, hydraulic ram, blas t load and response of the structural parts (altitude dependant), • Component probability of destruction from blast, pr obability of kill or survivability of the whole aircraft, given a hit (single hit or salvo) o btained through the fault tree and all the components or structure kill probabilities. ALBAS: An Integrated Software for Carrying Out Parametric Vulnerability /Lethality PLEIADES/A Calculations RTO-MP-AVT-153 10 3 UNCLASSIFIED/UNLIMITED UNCLASSIFIED/UNLIMITED 2.3 PLEIADES/A functionalities Via a Graphical Users Interface (GUI), PLEIADES/A c alculations can be run according two modes: an interactive mode or a batch mode. The interactive mode provides: • Manage target and warhead database, set interaction parameters, calculate step by step since burst point date, • Visualise partial and global results with graphical interfaces, calculate lethality grid 3 ([3]), create probabilities table for bay target model, re co d all significant operations The batch mode provides: • Replay recorded operations; compute multiple simula tions and their post processing. 3 The software projects a Cartesian grid onto the tar ge [3]. The probability of neutralization of the t arget’s functions following the impact of a projectile are then calcu lated at each grid cell centre considering a direct ion of impact perpendicular to the grid. A ray tracing based calc ul tion is then performed so that to evaluate the l ev l of damage and, as consequence, critical components breakdown, providi ng finally the kill probabilities of the affected f unctions ALBAS: An Integrated Software for Carrying Out Parametric Vulnerability /Lethality PLEIADES/A Calculations 10 4 RTO-MP-AVT-153 UNCLASSIFIED/UNLIMITED UNCLASSIFIED/UNLIMITED 2.4 PLEIADES/A current improving activities As represented in the figures 1 and 2 and indicate d bove, physical experiments conducted on small-scaled targets (sample, structure model) or d ecommissioned aircraft have been conducted at CEG since the 1980’s. After that, since the 1990’s, numerical simulations using full physics codes (namely Ouranos and/or Abaqus) have been realised a t CEG. These tests and calculations (models assessments) have permitted to analyse and evaluate effects of different types of threat on component or group of components. Functioning of the complete target (i.e. an aircraft) after possible degradati on at the component level is done using the FTA analys is. Figure 1 : Vulnerability analysis methodology Coupling or Threat Effects Survival Probability Functional Analysis Level of Susceptibility or Vulnerability Mission THREAT AIRCRAFT