Malgaigne fractures are the most common and widespread pelvic injuries resulting from the shear forces the action mechanism of which has not been explained in the literature yet. Military accidents with improvised explosive devices (IED) perfectly reflect this type of pelvic fracture. The finite element (FE) model of lumbar-pelvic complex (LPC) was developed based on computed tomography (CT) scans with the seat including steel frame, padding and soft tissue. The correlation coefficients of both low (100 N) and high (500 N) loads were greater than that currently obtained in the literature due to the presence of muscle force, pubic symphysis and joint cartilage. The dynamic analysis was performed to determine the influence of varying kinds of foam materials i.e. polyurethane, aluminium honeycomb structured and polyurethane auxetic foam on the stress/strain distribution in LPC under vertical impact load with the velocity of 7 m/s. Performed analysis showed the first fracture occurred in the L5 vertebrae resulting in the sacroiliac ligaments disruption and stress concentration in the pelvic ring causing further fractures of the wing of ilium, pubis and ischium bones. This results clearly explain the inconclusive findings about the second fracture that occurs in the pelvic area under a vertical impact load. The applied seat padding foam significantly reduced the stresses transmitted to the anatomical structures, thereby avoiding the risk of pelvic fracture. The analysis has proven that the auxetic polyurethane foam can be used as a good energy absorber.

The paper presents research on optimization of two-layer armour subjected to the normal impact of the 7.62x54 B32 armour piercing (AP) projectile. There were analysed two cases in which alumina Al₂O₃ was supported by aluminium alloy AA2024-T3 or armour steel Armox 500T. The thicknesses of layers were determined to minimize the panel areal density whilst satisfying the constraint, which was the maximum projectile velocity after panel perforation. The problem was solved through the utilization of LS-DYNA, LS-OPT and HyperMorph engineering software. The axisymmetric model was applied to the calculation in order to provide sufficient discretization. The response of the aluminium alloy, armour steel and projectile material was described with the Johnson-Cook model, while the one of the alumina with the Johnson-Holmquist model. The study resulted in the development of a panel optimization methodology, which allows the layer thicknesses of the panel with minimum areal density to be determined. The optimization process demonstrated that the areal density of the lightest panel is 71.07 and 71.82 kg/m² for Al₂O₃-Armox 500T and Al₂O₃-AA2024-T3, respectively. The results of optimization process were confirmed during the experimental investigation.

This article presents the description of the mechanism of selected dysfunctions of the human skeletal system and internal organs. The problem is wide and requires extensive experimental and numerical research. This article presents the outline of the problem regarding the creation of personal injuries of soldiers inside armored vehicles. The explanation of the mechanism of injuries caused as a result of strong effects of pulse forces, resulting from both the consequences of the wave of pressure created during an explosion, as well as high accelerations of the vehicle’s hull, is presented herein. Examples of the results of numerical analyses of the pressure wave impact from an explosion are presented in the Article. LS-Dyna software was used to perform the numerical calculations. The analyses were carried out using the Conwep algorithm implemented in the calculation code. The significance of calculation methods, thanks to which it is possible to recreate a simulation in which there is a risk of injuries of soldiers without posing a threat to their health and life, should be noted here. The main parts of the human body, such as the bottom limb, the pelvic belt, the cervical spine and the abdomen, have been considered. Mechanisms causing typical injuries of soldiers inside vehicles under which explosives are detonated have been analyzed for particular body parts through multiple numerical simulations. The analysis of the process of injury creation has been conducted on the basis of the statistical data regarding the most common injuries of soldiers. The validation process of numerical analyses was carried out using the results of experimental research.

As a result of an explosion under a military vehicle, the risk of threat to life and health of the crew increases. Examination of this event in terms of the security of soldiers comes down to a complex analysis of the mutual interaction of the body of a soldier, seating and structural elements of the vehicle. As a result, shock wave impacts can cause tremor resulting from the construction of the vehicle and acceleration of the passenger's body. This study attempts to analyze the impact of an explosion of an improvised explosive device (IED) under the military vehicle with the risk of cervical spine injuries of soldiers. The analysis was carried out using numerical methods in the LS-DYNA program and was carried out taking into account the variable displacement values and acceleration recorded during the\ explosion. The study used a model of the body of a soldier in the form of a Hybrid III 50th Male Dummy.