Grzegorz Sławiński

Influence of Material Model on Tensile Loaded Joint

The paper deals with the numerical analysis of a tensile loaded riveted joint. Finite element simulations of the upsetting process were carried out with the use of Marc code to determine the residual stress field. The contact with friction is defined between the mating parts of the joint. The computations were performed for four cases of material and load conditions and a comparison was performed on the basis of results obtained for standard elasto plastic and Gurson material models. Moreover, the influence of material model and residual stress on the tensile loaded joint was analyzed.

Analysis of Microslips and Friction in the Riveted Joints

The paper deals with analysis of contact stress fields and relative displacements as well as inspection of fretting phenomena in the neighborhood of mating surfaces of the riveted joint subjected to cyclic loading. The study of micro-local phenomena follows the riveting process analysis. Numerical FE simulations of the upsetting process are carried out to determine the residual stress and strain fields. Nondestructive testing methods are used for validation of numerical results. The contact with friction is defined between the mating parts of the joint. The influence of the initial load and sheet material model is studied. Maximum values of relative displacements are comparatively small but surface condition is strongly affected by sliding movements during cyclic loading. Plastic strain energy is taken into account for more efficient numerical analysis of the fretting wear.

Ochrona załogi pojazdu wojskowego przed wybuchem min i improwizowanych urządzeń wybuchowych (IED)

Abstract Risk of danger for military vehicle crew life and health increases when explosion under vehicle appears. Consideration of this phenomenon in the aspect of soldiers safety is based on coupled analysis of soldier’s body, car seat and vehicle construction elements. As the effect of blast wave interaction the vibrations of construction and passanger body acceleration appear. In the paper the analysis of improvised explosive device (IED) detonation under the military vehicle was carried out in the aspect of soldier neck spine injury. The analysis was made with the usage of numerical methods in LS Dyna computer code and considered the changeble values of displacement and acceleration registered during detonation. Streszczenie W wyniku eksplozji pod pojazdem militarnym wzrasta ryzyko zagrożenia życia i zdrowia załogi. Rozpatrywanie tego zdarzenia pod kątem bezpieczeństwa żołnierzy sprowadza się do złożonej analizy wzajemnych oddziaływań ciała żołnierza, siedziska i elementów konstrukcji pojazdu. W efekcie działania fali uderzeniowej występują oddziaływania powodujące drgania wynikające z wibracji konstrukcji oraz przyspieszenie ciała pasażera. W pracy podjęto próbę analizy wpływu eksplozji improwizowanego ładunku wybuchowego (IED) pod pojazdem militarnym na ryzyko powstania urazów kręgosłupa szyjnego żołnierzy. Analiza została wykonana z wykorzystaniem metod numerycznych w programie LS-DYNA i prowadzona była uwzględniając zmienne wartości przemieszczenia oraz przyspieszenia rejestrowane podczas wybuchu.

Protection of Military Vehicles Against Mine Threats and Improvised Explosive Devices / Ochrona Pojazdów Wojskowych Przed Wybuchem Min i Improwizowanych Urządzeń Wybuchowych

Abstract Military vehicles are exposed, among others, to mine and IED (Improvised Explosive Device) threats. Contemporary structural solutions cannot ensure their safety at maximum level. This paper presents a review of currently used structural solutions enhancing protection level against explosion. Furthermore, requirements for military vehicles safety against mine and IED threats are characterized. As well as that, sample results of energy absorbing panels examination results are shown. On this basis remarks to further development of protective structures are formulated. Streszczenie Pojazdy wojskowe są narażone na działanie m.in. fali wybuchowej min oraz improwizowanych urządzeń wybuchowych IED (z ang. improvised explosive device). Dotychczasowe rozwiązania konstrukcyjne pancerzy pojazdów wojskowych nie zapewniają ich ochrony na maksymalnym poziomie. W publikacji przedstawiono rozwiązania konstrukcyjne, których celem jest zwiększenie odporności pojazdów wojskowych na eksplozję ładunków wybuchowych. Ponadto scharakteryzowano wymagania dotyczące odporności pojazdów wojskowych na wybuch min i urządzeń IED. Przedstawiono również przykładowe wyniki badań paneli energochłonnych oraz sformułowane na ich podstawie wnioski do dalszego rozwoju konstrukcji ochronnych.

Research protective shield, elastomer-liquid against impact shock wave

An article describes an issue of increasing the passive safety of soldiers in a military vehicle subjected to loads resulting from explosion mine or IED. Traditional methods to increase security involving the application of additional layers made using materials with high density. This approach contributes to a reduction mobility and efficiency vehicle on the battlefield. For these reasons, it is necessary to search new design solution, which will benefit lowdensity material through which driving parameters of vehicle in combat do not worsen. Mentioned reasons led to propose a new concept protective shield made of elastomer with inclusion in form of a liquid. Effectiveness of the proposed protective shield will be verified on the bench traverse. The blast shock wave will be induced by detonation of HE charge at the central point over 430 mm from the top surface of the range stand. Experimental tests will be used to validate the numerical model. After positive validation and verification, numerical model it can be used for other blast conditions or optimize protective shield. FEM numerical modelling, dynamic simulations and postprocessing were carried out using the following CAE systems: CATIA, HyperMesh, LS-DYNA (a solver), LS-PrePost.

Risk Assessment Regarding the Injuries of the Lower Limbs of the Driver of a Military Vehicle in the Case of an Explosion Under the Vehicle

The protection of soldiers performing tactical operations in armoured vehicles plays an important role in combat operations. The need for such protection results from threats on battle-fields or during peace-keeping missions connected with the explosion of mines or Improvised Explosive Devices (IED). As a result of an explosion, the occupants of the vehicle are exposed to the effects of the shock wave as well as overloads caused by the movement of the vehicle. Simulation and experimental tests play a significant role in ensuring the safety of occupants exposed to the effects of loads caused by an explosion. It is possible to specify the conditions creating loads to the body, and also to determine interaction forces in the lower libs of the human body, using models which include the description of the explosive, parameters of the vehicle and the model of the human body.

Numerical Analysis of the Biomechanical Factors of a Soldier Inside a Vehicle with the Pulse Load Resulting from a Side Explosion

The aim of this paper is to try to classify and assess the risk of injuries of the cervical spine during an attack on a military vehicle. In that case, the focus has been placed only on the side explosion variant, which reflects new threats observed on the basis of events from Afghanistan and not only. The risk of a threat to the life and health of the vehicle’s crew increases as result of an explosion under a military vehicle. Considering that event in terms of the safety of soldiers comes down to a complex analysis of interactions between the soldier’s body, seat and vehicle’s structural elements. The effects of the shock wave result in interactions which cause vibrations resulting from the vibrations of the construction and the acceleration of the occupant’s body.

Proving Ground Tests of Selected Energy Absorbing Structure Variants Under a Shock Wave Load

Military actions conducted in the XXI century in Iraq and Afghanistan have shown that the tactical and technical solutions applied so far are not sufficiently effective in wars, in which one side of the conflict has a significant advantage over the other. The most effective weapon employed in the strategy of combat engagements are Improvised Explosive Devices, so called IEDs. They are most frequently placed on roads travelled by allied forces vehicle convoys. According to the statistics, they were the cause of death of approximately 40% of all soldiers killed when fighting in Afghanistan and Iraq between 2003 and 2011. In order to increase the safety of a vehicle’s crew against the shock wave of a mine and IED explosion, An additional layer in the form of a protective panel will be aimed at decreasing the inertial force affecting the vehicle’s passenger during an AT mine or IED explosion, which is the primary cause of injuries sustained by vehicle personnel.

Application of a bus seat buffer to mitigate frontal crash effects

The paper considers the problem of coach occupant safety during crash events. The authors present a simple low-cost seat buffer concept which may mitigate the effects of frontal impact. The method ...

A Comparison Between Two Different Methods of Blast Modelling

This dissertation consists mainly in a comparison of different methods of load modelling relative to the blast wave coming from the detonation of a bursting TNT charge and the impact of this wave on a shield.