This case study describes the development and optimization of a weight-optimized ballistic protection system for armoured cars, trucks and commercial vehicles. The focus is on reducing the overall mass while maintaining the protective effect against machine gun fire (7.62 mm AP) and explosions (grenade pressure wave). Particular attention is paid to compliance with the driving license limit for civilian vehicles with a maximum permissible total weight of 3.5 tons. To this end, holistic lightweight construction principles and combined analytical-numerical optimization strategies are used.
The initial situation
A leading specialist supplier of armored civilian vehicles commissioned the development of a modular armoring system for cars and light trucks. The challenge: to comply with STANAG 4569 Level 2 and VPAM BRV 2009 protection classes without exceeding the 3.5-ton driving license limit. The vehicle should be civilian-approved and offer protection against ballistic and explosive threats.
The challenge
The protection systems must protect against hard-core ammunition and blast waves after an explosion. The explosion generates an overpressure front, which causes structural load peaks. At the same time, the vehicle balance must be maintained to ensure handling and safety.
The load assumptions include:
Ballistics: 7.62 mm AP projectile at 830 m/s
Explosion load: pressure wave with a peak overpressure of 1.5 bar and rise times <1 ms
Interdisciplinary approach
Lightweight material construction: Use of ceramic panels, arch-structured sandwich systems for load distribution, fibre composites (e.g. UHMWPE, aramid), hybridized with aluminium sandwich panels
Structural lightweight construction: Topology and topography optimization of primary and secondary support structures using non-linear FEM
Lightweight system construction: Analysis of center of gravity, moments of inertia and body load distribution for mass savings at system level
FE load simulations: Use of special non-linear explicit FE solvers (lagrange) to describe the projectile impact with material failure; CFD-FEM coupling for modeling pressure waves
Multiscale modeling: Detailed analysis of individual layers to describe delamination, fragmentation and energy absorption
The result
The interior of the vehicle, the armouring and peripheral areas were optimized in their entirety. A mass saving of approx. 30 % was achieved. The vehicle continues to meet the protection requirements of VPAM BRV 2009 Level VR7 and STANAG 4569 Level 2. At 3.2 tons, the permissible total weight remains below the 3.5 ton limit for civilian driving license classes. Thanks to modular attachment systems, the protective effect can be scaled to suit the specific mission
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