Physical Modelling of Mine Blast Impact on Armoured Vehicles

Transcription

1 IOP Conference Series: arth and nvironmental Science PAPR OP ACCSS Physical odelling of ine Blast Impact on Armoured Vehicles o cite this article: ika Bochorishvili et al 016 IOP Conf. Ser.: arth nviron. Sci View the article online for updates and enhancements. his content was downloaded from IP address on 09/0/019 at 18:19

2 Physical odelling of ine Blast Impact on Armoured Vehicles ika Bochorishvili 1, ikoloz Chikhradze 1,, dgar ataradze 1, Irakli Akhvlediani 1 1 G.sulukidze ining Institute, 7, indeli str, 1086, bilisi, Georgia Georgian echnical University, 0175 bilisi, Georgia mail address: bochorishvili@mining.org.ge Abstract. Studies related to the impact of a mine blast on armoured vehicles focus on aspects such as i) dynamic loads acting on the armoured vehicle at the moment of mine blast; ii) armoured vehicle response under the impact of a dynamic load; iii) dynamic loads acting on the crew and the assessment of potential human traumas. he paper presents similarity criteria for physical modelling of the mine blast under the armoured vehicle and the results of modelling of dynamic behaviour of vehicles. Similarity criteria, established as a result of the analysis of the governing parameters and similarity theory, are adequate to the processes of blast impact on the vehicle. odelling experiments were conducted in the underground experimental base of the ining Institute especially designed for the study of explosion processes. Physical modelling can be used for preliminary studies with the purpose of the evaluation of the protective level of armoured vehicles as well as for pretesting experiments in accordance with SAAG 4569 requirements. 1. Introduction Designing of explosionresistant armoured vehicles and evaluating the protection level to blast mine threats requires a comprehensive study of blast impact processes. At present, such studies are conducted primarily by means of experimental or computer modelling, while the application of physical modelling methods is relatively rare although the latter has obvious advantages for certain types of tasks [1,,,4,5]. or example, the study of dynamic behaviour of vehicles during largescale variation of dynamic loads, including near critical, through experimental or computer modelling is both difficult and expensive. he use of physical modelling potential in the design and testing of armoured vehicles is restricted due to the lack of the conditions of similarity between a model and a reallife prototype. Strict observance of the conditions of similarity between a model and its reallife prototype is essential for meeting the objective. According to the theory of modelling, the following characteristics are required and are sufficient for similarity: a) qualitative homogeneity; b) dimensionless combination of their governing parameters shall be equal. he parameters governing the process of a blast impact of on an armoured vehicle depend on blast conditions and vehicle properties, as well as on the conditions of interaction between dynamic loads and a vehicle. Content from this work may be used under the terms of the Creative Commons Attribution.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. Published under licence by td 1

3 . Similarity Criterion.1 Similarity Criteria for xplosions Overpressure during mine blast under armoured vehicle equals overpressure in the model P = P, when 1 1 (1) Where: and are the distance from the centre of the charge to the underside of the chassis in the prototype and in the model, measured in m; and blast energy in the prototype and in the model, measured in J... Similarity criteria of dynamic processes Studies conducted by applying the provisions of the theory of dimensions and Π theorem have allowed to establish criteria of similarity between a reallife prototype and a model, which is a dimensionless combination of governing parameters: V I G V I G () Where: and force in the prototype and in the model; and time in the prototype and in the model; G and G acceleration in the prototype and in the model; and modulus of elasticity in the prototype and in the model; and linear dimensions in the prototype and in the model; and mass in the prototype and in the model; I and I pressure impulse in the prototype and in the model; V and V movement velocity in the prototype and in the model. he following independent criteria were obtained for dimensionless combination of a reallife prototype and a model: () (4) I I (5) V G V G (6)

4 o the aforementioned criteria shall be added the criterion of equality of Poissons ratio of reallife prototype and model material: (7) he values of factors of similarity between a reallife prototype and a model are given in able 1. able 1. actors of similarity between a reallife prototype and a model # Parameter Dimensions Scale factor 1 inear dimension [] K = / ass [] K = / = K ime [] K = / = K Pressure [] [ 1 ] [ ] 1 5 Pressure pulse [] [ 1 ] [ 1 ] K I = I / I = K orce [] [] [ ] K = / = K 7 Velocity [] [ 1 ] K V = V / V = K Acceleration [] [ ] 1 9 inear displacement [] K X = X /X =K 10 odulus of elasticity [] [ 1 ] [ ] 1 11 Poisson s ratio 1 1 Strength [] [ 1 ] [ ] 1. Physical odel of Armoured Vehicle he scale factor of the physical model for linear dimension is K =. he model contains four support stands, a bottom plate, an upper plate and extra mass. he plate has the following dimensions: 190 mm x 790 mm, thickness 8 mm. It is made of steel. he compressive strength is 480 kg/mm. he distance between the floor and the bottom plate is regulated by means of hydraulic jacks and ranges between cm with 5 cm intervals (igure 1). igure 1. 1 support stand, bottom plate, extra mass, 4 sensors, 5 charge

5 he weight of the model encompasses 57 kg. o meet the similarity criteria, the model must weigh 900 kg. herefore, evenly distributed steel blocks are placed in the front and back parts of the model. he total weight of the blocks is 7 kg. 4. Results and Discussions 4.1 Overpressure distribution on the vehicle bottom plate Conditions of the experiments: the charge was placed on the floor, below the geometrical centre of the bottom plate. he charge weight in the model was 0. kg and the vertical distance from the charge to the plate was 16.6 cm. he floor was made of a 6 mm thick steel plate fixed into a concrete plate, the thickness of which is 50 cm. Overpressure was measured with PCB 10B sensors, acceleration with accelerometer PCB 50 B0 and velocity with velocimeter VBP. Data were recorded by means of ektronix 40A oscilloscope. he layout of sensors on the bottom plate is presented in igure. igure. ayout of sensors on the bottom plate. S1S9 overpressure sensors, A accelerometer, V1 and V velocimeters According to oscillograms, the duration of overpressures in the models does not exceed 57 ms (igure ). In real conditions, overpressures last for 81 ms. igure. Overpressure histories on the bottom plate (W= 0. kg, R= 16.6 cm) 4

6 igure 4 and 5 show the mean values of overpressures acting on the bottom plate in the transversal and longitudinal directions when the charge weight in the model was 0. kg, and the distance from the floor to the bottom plate was m. In real conditions the distance is m, and the weight charge is 6.0 kg. igure 4. Overpressure distribution in the direction of the transverse axis of the bottom plate. 1 section 11; section igure 5. Overpressure distribution in the direction of longitudinal axis of the bottom plate. 1 section ; section Vertical displacement, velocity and acceleration In the conditions of the experiment, when the charge was located on the steel floor, the vehicle started moving after the detonation of ms, while the entire duration of the movement is 040 ms (igure 5, 6). Results of experiments are shown in able. 5

7 igure 6. Velocitygram of motions of the model. 1 forebody; back part) igure 7. Accelerogram of motions of the model able. Kinematic characteristics of the motion Charge weight, [kg] odel Real easurement place ront side of the bottom plate Back side of the bottom plate Centre of the bottom plate ront side of the bottom plate Back side of the bottom plate Centre of the bottom plate Velocity, [m/s] odel Real Displacement, [cm] odel Real Acceleration, [g] odel Real

8 5. Conclusions Similarity criteria, established as a result of the analysis of the governing parameters and similarity theory, are adequate to the processes of blast impact on the vehicle. Physical modelling can be used for preliminary studies with the purpose of evaluation of the protective level of armoured vehicles as well as for pretesting experiments in accordance with SAAG 4569 requirements. References [1] AP55. Procedures for valuating the Protection evel of ogistic and ight Armored Vehicles. Volume for ine hreat, 006. [] RH090 est ethodology for Protection of Vehicle Occupants against AntiVehicular andmine ffects, 007. []. Hönlinger, U. Glauch, G. Steger. odelling and Simulation in the Design Process of Armoured Vehicles pdf. 00. [4] Williams, K., cclennen, S., Durocher, R., StJean, B, and remblay, J. Validation of oading odel for Simulating Blast ine ffects on Armoured Vehicles 7th International S DYA User s Conference, 6, [5]. Kania, Development tendency of landmine protection devices, odelling and Optimization of Physical Systems, 8, pp. 677, Gliwice,