## 1 Introduction  
Mine Resistant Ambush Protected (MRAP) vehicles are used by the military in urban and confined areas. They are deployed in command and control reconnaissance missions, to support convoy movements, to conduct medical evacuations and in explosive ordinance disposal [1]. MRAPs have a long history dating back to the conflicts in Southern Africa [2] but are still in use today The United States recently agreed to deliver 440 MaxxPro MRAPs as part of its military support for Ukraine during 2022 [3]. MRAPs usually employ V-shaped hull structures to protect their passengers from the devastating effects of improvised explosive devices and anti-vehicle landmines when detonated beneath the vehicles. Huge amounts of energy are released when explosive charges are detonated, and this is directed towards the MRAP vehicle's hull through the blast shock front. Without any means to mitigate the blast, the explosion will cause localized structural damage and exert large global accelerations on the vehicle's structure. The vertical momentum transfer may cause the vehicle to move upwards, injuring the passengers. If the localized structural damage results in floor rupture, the blast shock, fragments, ejecta (if a buried charge is detonated), fireball and explosion products will enter the MRAP with potentially lethal effects. The V-structures used in MRAP vehicles mitigate the blast by laterally deflecting the explosive shock waves away from the passenger compartment, reducing the loading transmitted through the compartment floor and lowering the vertical global impulse transfer to the vehicle [2; 4; 5; 6]. Over the last 50 years, the use of V-structures has reduced injury rates from explosive charges detonated under the centre of vehicles' undersides [7]. Various researchers [5; 8; 9; 10; 11; 12; 13; 14; 15; 16; 17; 18] have studied the impulse and permanent damage imparted to scaled versions of these V-structures. This work often involved small-scale explosive testing on flexible structures [5; 8; 9; 10; 11; 12] and numerical simulations using hydrocodes [4; 13; 14; 15; 16; 17; 18; 19; 20]. Damage was observed in the form of large plastic deformation and the presence of ridge buckling [5; 8]. The damage was localized to the immediate vicinity of the explosion (directly beneath the apex of the V-structure). The results showed that the impulse transfer strongly depended on the internal V-angle [5; 9; 10; 11; 12; 13; 14]; lower internal angles were more effective mitigators, as might be expected, given that the mitigation mechanism was lateral blast-load deflection. The superiority of the V-structure over other designs has been demonstrated for both air-blast and buried explosions [13; 14; 15; 16; 17; 18; 19; 20]. Numerical studies by [PERSON] et al. [17] confirmed that the internal V-angle was the major factor in influencing the initial plate acceleration and was even more significant for impulse transfer. However, lowering the internal angle raises the vehicle height: this has a detrimental effect on the handling performance, increases the battlefield silhouette (for combat arenas) and lowers vehicle mobility by raising the centre of mass [6; 21]. Full-scale experiments of MRAP vehicles are not generally reported in the open literature, but results from LS-Dyna simulations of a \"typical\" full-scale MRAP vehicle have been published [22]. A small flat section at the ridge of the V-structure that comprised the vehicle hull bottom was apparent, probably due to the practical difficulty of manufacturing a V-structure with a tight bend radius. This raises some questions about the applicability of other work [5; 8] using a very tight bend radius of 2 mm. The V-structure simulations in [22] exhibited lower floor accelerations, kinetic energy and reductions in the local and global maximum velocities when compared to the same charge detonation under a vehicle with a flat bottom. Concerns were raised about the stability of the vehicle and the reduced interior space.