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3. NUMERICAL MODELLING OF THE PS AND SPS SYSTEMS a In the simulations and range tests, the 6 kg TNT spherical charge was applied, suspended centrally over the SPS system, distanced by 400 mm from the top frame surface. A detonator was placed centrally inside the sphere. The 5 mm thick protected plate was made of Armox 500T armoured steel.

Figure 3 3. NUMERICAL MODELLING OF THE PS AND SPS SYSTEMS a In the simulations and range tests, the 6 kg TNT spherical charge was applied, suspended centrally over the SPS system, distanced by 400 mm from the top frame surface. A detonator was placed centrally inside the sphere. The 5 mm thick protected plate was made of Armox 500T armoured steel.

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Fig. 2. The top view on the ALF square panel used in range tests (the holes for the erected bolts are depicted) The LV/LAV vehicle protective shield is divided into panels shaped and dimensioned according to the shape and dimensions of the vehicle body shell bottom. In the failure case the panels are exchanged. The maximum overall dimensions of the panels are 500x500 mm. The panels are connected to the vehicle bottom plate with erection bolts having increased strength and protection against unbolting. There are used M16 bolts with heads welded point wisely on vehicle bottom plate, from the vehicle body inside and using self-blocking shaped nuts (Figs. 1 and 2).
Fig. 2. The top view on the ALF square panel used in range tests (the holes for the erected bolts are depicted) The LV/LAV vehicle protective shield is divided into panels shaped and dimensioned according to the shape and dimensions of the vehicle body shell bottom. In the failure case the panels are exchanged. The maximum overall dimensions of the panels are 500x500 mm. The panels are connected to the vehicle bottom plate with erection bolts having increased strength and protection against unbolting. There are used M16 bolts with heads welded point wisely on vehicle bottom plate, from the vehicle body inside and using self-blocking shaped nuts (Figs. 1 and 2).
Fig. 3. The basic dimensions and main cross-sections of the BTPS range stand (Klasztorny, 2010a)
Fig. 3. The basic dimensions and main cross-sections of the BTPS range stand (Klasztorny, 2010a)
Tab. 2. Quantities and thicknesses of the FE layers in particular components of the SPS numerical model The erection bolts in the range stand are designed to work inthe elastic range, so they can be modelled approximately as bars with the equivalent square cross-section. The erection bolts in the ALF panels were modelled more accurately, i.e. with circular cross-sections taken into account. The stiffened subsoil was limited to the cubicoidal volume 2000x2000x1000 mm.
Tab. 2. Quantities and thicknesses of the FE layers in particular components of the SPS numerical model The erection bolts in the range stand are designed to work inthe elastic range, so they can be modelled approximately as bars with the equivalent square cross-section. The erection bolts in the ALF panels were modelled more accurately, i.e. with circular cross-sections taken into account. The stiffened subsoil was limited to the cubicoidal volume 2000x2000x1000 mm.
Fig. 5. Components of the PS system resting on the supporting plate and the subsoil (FE mesh of the system quarter) Because of bisymmetry of the PS and SPS systems, their numerical models were limited to respective quarters of the global systems. The boundary conditions in the planes of symmetry eliminate displacements perpendicular to these planes. The nu- merical models of the PS and SPS systems are shown in Figs. 5 and 6.
Fig. 5. Components of the PS system resting on the supporting plate and the subsoil (FE mesh of the system quarter) Because of bisymmetry of the PS and SPS systems, their numerical models were limited to respective quarters of the global systems. The boundary conditions in the planes of symmetry eliminate displacements perpendicular to these planes. The nu- merical models of the PS and SPS systems are shown in Figs. 5 and 6.
Fig. 6. Components of the SPS system resting on the supporting plate and the subsoil (FE mesh of the system quarter)
Fig. 6. Components of the SPS system resting on the supporting plate and the subsoil (FE mesh of the system quarter)
Tab. 4. Material constants for components working in the elastic range
Tab. 4. Material constants for components working in the elastic range
Tab. 3. Material constants for Armox 500T steel and PA11 aluminium
Tab. 3. Material constants for Armox 500T steel and PA11 aluminium
Tab. 5. The average values of material constants for uniform composites $,C,A St3 steel, 10.9 bolt steel and hardened range subsoil LS-Dyna material type: MAT_24 (MAT_PIECEWISE_LINEAR_PLASTICITY)
Tab. 5. The average values of material constants for uniform composites $,C,A St3 steel, 10.9 bolt steel and hardened range subsoil LS-Dyna material type: MAT_24 (MAT_PIECEWISE_LINEAR_PLASTICITY)
Fig. 7. The normal stress vs. volumetric strain load curve in the uniaxial compression test for ALPORAS aluminium foam
Fig. 7. The normal stress vs. volumetric strain load curve in the uniaxial compression test for ALPORAS aluminium foam
Rys. 8. The axial force vs. the actual change in the gauge length (average experimental data) in the uniaxial tension test for SOUDASEAL 2K glue specimens
Rys. 8. The axial force vs. the actual change in the gauge length (average experimental data) in the uniaxial tension test for SOUDASEAL 2K glue specimens
Fig. 10. The SPS system before 6 kg TNT blast test Fig. 9. Segment SP with M16 erection bolts before 6 kg g TNT blast test
Fig. 10. The SPS system before 6 kg TNT blast test Fig. 9. Segment SP with M16 erection bolts before 6 kg g TNT blast test
Fig. 11. The SPS system after 6 kg TNT blast test
Fig. 11. The SPS system after 6 kg TNT blast test
ig. 12. The plastic deformation 3D scan (performed using Handyscan) for the protected plate removed from SPS system after 6 kg TNT blast: a) the vertical displacement contours; b) the virtual model of the deformed plate The simulations correspond to detonation of 6 kg TNT spheri- cal charges in the PS and SPS systems. The results presenting the ALF panel failure picture and plastic deflection of the protected plate in the SPS system have been used to validate experimental- ly numerical modelling and simulation of the SPS system.
ig. 12. The plastic deformation 3D scan (performed using Handyscan) for the protected plate removed from SPS system after 6 kg TNT blast: a) the vertical displacement contours; b) the virtual model of the deformed plate The simulations correspond to detonation of 6 kg TNT spheri- cal charges in the PS and SPS systems. The results presenting the ALF panel failure picture and plastic deflection of the protected plate in the SPS system have been used to validate experimental- ly numerical modelling and simulation of the SPS system.
Fig. 13. The SPS and PS systems loaded by 6 kg TNT blast shock wave. Time histories of the relative vertical deflection at the central point of the protected plate
Fig. 13. The SPS and PS systems loaded by 6 kg TNT blast shock wave. Time histories of the relative vertical deflection at the central point of the protected plate
Fig. 15 presents the plastically deformed protected plate in the PS system. The next Fig. 16 shows a half of the SPS system in the axonometric view at instant f=1.05 ms corresponding to the maximum vertical deflection in the protected plate. In Fig. 17 one can observe the deformed and partly damaged SP subsystem extracted from the SPS system at the instant corresponding to the maximum vertical deflection in the protected plate. Fig. 14 presents time-histories of the vertical acceleration at the midpoint of the protected plate for the PS system (red line) and the SPS system (black line). The physical correctness of these curves is observed. Small reduction in accelerations at the midpoint of the protected plate is observed. It results from the structural and boundary conditions in both systems. The max- imum vertical accelerations overpass time and again the admissi- ble values for a human. Note that the range stand does not reflect LV or LAV vehicle. There are modelled PS and SPS systems and the results cannot be directly interpreted for screw-occupants. One may compare only the maximum values in the PS and SPS systems before developing the algorithm transforming the range results to real vehicles.
Fig. 15 presents the plastically deformed protected plate in the PS system. The next Fig. 16 shows a half of the SPS system in the axonometric view at instant f=1.05 ms corresponding to the maximum vertical deflection in the protected plate. In Fig. 17 one can observe the deformed and partly damaged SP subsystem extracted from the SPS system at the instant corresponding to the maximum vertical deflection in the protected plate. Fig. 14 presents time-histories of the vertical acceleration at the midpoint of the protected plate for the PS system (red line) and the SPS system (black line). The physical correctness of these curves is observed. Small reduction in accelerations at the midpoint of the protected plate is observed. It results from the structural and boundary conditions in both systems. The max- imum vertical accelerations overpass time and again the admissi- ble values for a human. Note that the range stand does not reflect LV or LAV vehicle. There are modelled PS and SPS systems and the results cannot be directly interpreted for screw-occupants. One may compare only the maximum values in the PS and SPS systems before developing the algorithm transforming the range results to real vehicles.
Fig. 17. The SPS system after 6 kg TNT blast shock wave. The side view: a) simulation; b) experiment to the instant at which the maximum vertical deflection in the protected plate has occurred. The Huber-Mises-Hencky effective stress contours [GPa] in the protected plate, at the same dynamic conditions, are shown in Figs. 20 and 21. Contours illustrating the effective plastic strains [ - ] in the protected plate after finishing the dynamic process are presented in Figs. 22, 23 for the PS and SPS systems, respectively. ig. 18. The PS system loaded by 6 kg TNT blast shock wave. Contours of the vertical displacements [mm] of the protected plate at instant t=0.70 ms (the maximum deflection of the plate)
Fig. 17. The SPS system after 6 kg TNT blast shock wave. The side view: a) simulation; b) experiment to the instant at which the maximum vertical deflection in the protected plate has occurred. The Huber-Mises-Hencky effective stress contours [GPa] in the protected plate, at the same dynamic conditions, are shown in Figs. 20 and 21. Contours illustrating the effective plastic strains [ - ] in the protected plate after finishing the dynamic process are presented in Figs. 22, 23 for the PS and SPS systems, respectively. ig. 18. The PS system loaded by 6 kg TNT blast shock wave. Contours of the vertical displacements [mm] of the protected plate at instant t=0.70 ms (the maximum deflection of the plate)
lab. 6. The plastic deflection of the protected plate d [mm] in the PS, SPS systems after 6 kg TNT blast shock wave (N - simulation E - experiment) In reference to the SPS system error ll is relatively small. Quantitative conformity of the numerical and experimental failure in the ALF shield is assessed positively. Summing up, experi- mental validation of numerical modelling has been assessed positively with possibility of further improvement of the numerical models. Attention should be put on better modelling of laminate delamination as well as on better modelling of fully compacted aluminium foam at tension. Moreover, the material models de- scribing aluminium foam, hybrid laminates, and glue could be extended on high strain rates.
lab. 6. The plastic deflection of the protected plate d [mm] in the PS, SPS systems after 6 kg TNT blast shock wave (N - simulation E - experiment) In reference to the SPS system error ll is relatively small. Quantitative conformity of the numerical and experimental failure in the ALF shield is assessed positively. Summing up, experi- mental validation of numerical modelling has been assessed positively with possibility of further improvement of the numerical models. Attention should be put on better modelling of laminate delamination as well as on better modelling of fully compacted aluminium foam at tension. Moreover, the material models de- scribing aluminium foam, hybrid laminates, and glue could be extended on high strain rates.
Impact in the form of the 6 kg TNT blast shock wave induces plastic deformations in the Armox plate in both PS and SPS sys- tems. The plastic deflection can be treated as the measure of these deformations. Respective numerical and experimental values of the plastic deflection are collected in Tab. 6.
Impact in the form of the 6 kg TNT blast shock wave induces plastic deformations in the Armox plate in both PS and SPS sys- tems. The plastic deflection can be treated as the measure of these deformations. Respective numerical and experimental values of the plastic deflection are collected in Tab. 6.
Fig. 22. The PS system after 6 kg TNT blast shock wave. Contours of the effective plastic strains [-] in the protected plate
Fig. 22. The PS system after 6 kg TNT blast shock wave. Contours of the effective plastic strains [-] in the protected plate
Fig. 23. The SPS system after 6 kg TNT blast shock wave. Contours of the effective plastic strains [-] in the protected plate
Fig. 23. The SPS system after 6 kg TNT blast shock wave. Contours of the effective plastic strains [-] in the protected plate
Related topics:
Numerical SimulationsFinite Element MethodsFinite Element Analysis (FEA)
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