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Critical infrastructure, military or civil equipment, buildings, and Light Armored Vehicles (LAV) can be exposed to blast and ballistic loading during their lifetime. Such loads can cause large deformations and stresses within a very short period of time. For that purpose, it is necessary to examine and improve their response to these high-intensity and short-term loads. The analytical approaches are complex, the performance of large-scale experimental tests is extremely expensive since it involves a number of experts, special legal permits, and safety requirements which makes numerical analysis the most valuable examination tool. On the other side, a precise numerical analysis requires precise material properties, to describe the material behavior under various conditions. Before analyzing the response of structures under blast loads, the numerical model should be carefully validated first. This paper presents the validation results of the numerical model of small-scale explosion tests of charges laid on the ground or buried in the soil. The numerical results for time of arrival, maximum pressure, and specific impulse are compared with the experimental results showing a good correlation. The influence of depth of burial (DoB) on blast wave development and soil ejecta formation and loading parameters is investigated in detail.

Gravel-filled arrester beds, also called safety-escape ramps or vehicle run-out areas, have long been a road-safety feature for safely stopping heavy road vehicles from running off the road. In the recent past, there has been consideration given to installing these features on highway access ramps to provide safe areas to stop passenger cars driving at highway speeds. The work presented in this article was performed to investigate the behaviour of standard-size passenger cars on gravel-filled arrester beds, with a particular focus on the achievable vehicle decelerations and the ability of the arrester beds to safely stop a passenger car coasting in an uncontrolled manner. The findings show that the achievable average decelerations are in the range of 0.3 g for coasting vehicles and up to 0.9 g when the vehicles are braking. The results prove that more research is required to quantify the influence of the gravel parameters on the achievable decelerations.

At the present time of political and war conflicts between countries, more and more attention is focused on the protection of important structures, being part of critical infrastructure, such as buildings of energy importance, government buildings or military bases. Regardless of the type of industry area, primarily, buildings needed to be protected. For this reason, the paper is focused on the determination of resistance of selected structural elements creating the protection system against the effects of the blast from the explosion, including terrorist attack. The paper has need of analysing the behaviour of structural elements affected by the blast load and setting the structural resistance of elements loaded by such dynamic type of load. The outputs can serve as a basis for the design of an effective plan for the protection of a selected elements of critical infrastructure, which ultimately represents not only the protection of the buildings themselves, but also the affected people presented inside the buildings.

Many terrorist attacks in the last decade around the world have exposed the vulnerability of citizens in public places. The Migrant crisis in Europe additionally increased the intolerance among different ethnic groups leading to increased number of terrorist attacks at public places. Among others, explosive devices are often used at crowded public areas as in the case in Boston marathon 2013. Therefore blast protection of soft targets is very important issue in today’s world. Consequently the response evaluation of civilian objects, equipment and properties to this kind of loads becomes also important. For that purpose, this paper presents the results comparison between two different trash receptacles (non-blast resistant and improved design of blast resistant trash receptacle) taking into account the human injury criteria of the numerical HYBRID III 50% dummy by using the explicit code LS-DYNA.

A precise, simple and efficient blast response numerical analysis of Light Armoured Vehicles (LAVs) as well as other structures is of great importance in the early design stages of prototype development in order to reduce the final cost. One of the most commonly used modelling techniques for blast response analyses of structures is the Multi-Material Arbitrary-Language-Euler (MM-ALE) method. However, the method is quite demanding for use, especially when complicated geometries such as LAV designs are involved. This paper presents a review of the pros and cons of the MM-ALE modelling technique for blast response analysis of LAV according to the testing procedures required by the AEP-55 standard.

Continuous improvement in the hull floor of light armoured vehicles in terms of landmine response and crew safety is required among other things, in order to meet higher demands in the market and t...

Light armored vehicles (LAVs) can be exposed to blast loading by landmines or improvised explosive devices (IEDs) during their lifetime. The bottom hull of these vehicles is usually made of a few millimeters of thin armored plate that is the vehicle’s weak point in a blast-loading scenario. Therefore, blast resistance and blast load redirection are very important characteristics in providing adequate vehicle as well as occupant protection. Furthermore, the eccentric nature of loading caused by landmines was found to be omitted in the studies of simplified structures like beams and plates. For this purpose, blast wave dispersion and blast response of centrally and eccentrically loaded flat-, U-, and V-shaped plates are examined using a combined finite-element–smoothed-particle hydrodynamics (FE–SPH) model. The results showed that V-shaped plates better disperse blast waves for any type of loading and, therefore, can be successfully applied in LAVs. Based on the results of the study and the geometry of a typical LAV $$6\times 6$$ , the minimum angle of V-shaped plates is also determined.

The paper studies corporate governance characteristics in a panel of transition countries to investigate the relationship between the investment in intangible capital (specifically innovation) and corporate governance. We show that innovation is restricted by finance and the managerial attitude towards activities that support innovation. In case of financial restriction, softer innovation (process, marketing, organization) are more less impacted by the restriction and are also more common. Lack of managerial support to innovation results in less innovation, regardless of the type. We also show that external determinants, like the intensity of competition and international orientation, are related to innovation. The paper extends the knowledge about the link between corporate governance and intangible investment at large and in particular in transition countries. As such it provides useful implication at microeconomic as well as macroeconomic (developmental) level.

In this article, the process of deep rolling of the torsion bar for heavy armored vehicles is investigated. Deep rolling is a mechanical process of introducing compressive stresses into near surface regions of the working piece. The main objective of deep rolling of the torsion bar is to increase fatigue strength and life time of the torsion bar. The investigated specimen (quenched and tempered before deep rolling) was deep rolled according to the producer's standard technology procedure. The material used in this study was the TORKA steel, which is a low-alloy steel with high strength and toughness. The material was characterized through a series of monotonic and cyclic tension compression experiments. Parameters used in the process were changed during deep rolling of the specimen and their influence was measured. Residual stresses resulting from the deep rolling process were measured with an X-ray diffraction (XRD) device and evaluated with the use of commercial finite element method software. An isotropic and kinematic hardening material model based on the cyclic characteristics of the material was used in three dimensional simulation of deep rolling. Numerical simulation results agree very well with the results obtained from XRD measurements.

During the production of torsion bars, two different mechanical processes of inducing the residual stresses into the torsion bar are used: the presetting of the torsion bar and the deep rolling of the torsion bar. The process of presetting the torsion bar is carried out by twisting the torsion bar to the desired angle and releasing it to the new residual angle position. With controlled overstraining, favorable residual shear stresses are induced into the torsion bar, so the material is strain hardened and the yield point of the material is shifted and increased in the stress and strain space. The objective of the deep rolling process is to introduce compressive residual stresses into near-surface regions in order to increase the fatigue strength of the torsion bar. These two processes influence each other. The final level of residual stresses depends on the production sequence of these two processes and the production parameters of each process. The correct production sequence of these two operations and distribution of beneficial residual stress was simulated using the finite element (FE) method. To validate this model, the predicted surface residual stresses were compared by the X-ray diffraction (XRD) measurements of residual stresses.

This paper discusses the flow and fracture properties of high-strength armor steel PROTAC 500. Based on combination of both experimental and numerical studies, material parameters for the Johnson–Cook (JC) strength and fracture model were determined. For that purpose, experimental tensile tests were conducted at elevated temperatures (20–400 °C), various strain rates (0.001–1 s−1) and triaxialities of axisymmetric notched specimens (0.333–1.431). Some test specimens were photographed during the testing, and by means of image processing, input data for calculation of true stresses and strains up to the point of fracture were extracted. After determination of strength material parameters, tensile axisymmetric tests with different triaxialities were numerically simulated and triaxiality data from the simulations were taken for evaluation of the material parameters of the damage model. Validation study was also performed successfully. The results of this paper will enable numerical prediction of large deformation processes as well as possible fracture occurrence, its development and final size, for structures made of high strength armor steel, PROTAC 500.

Material failure is most often caused by cyclic fatigue loading. Prior to failure, material damage growth can be observed by means of various methods. Through experimental research, it has been determined that individual methods are appropriate only for specific types of materials and that analysis results also depend on the method of material loading. Therefore, a question is being raised on which method to choose for a specific material and method of loading. For this purpose, the paper presents the results of the damage initiation process and damage growth for high yield strength material Armox 500T, as well as for annealed low yield strength steel 42CrMo4. The measured data on material response are evaluated by means of three different methods which are based on the elastic modulus, plastic strain energy, and maximum stress. Parameters and damage values were obtained from the measurement data by means of various damage evaluation methods. After that, an overview was made of the differences between these methods. The results were used to determine the deficiencies and benefits of each method and the most appropriate method for subsequent tests was selected. The most frequently applied damage identification method, i.e. the elastic modulus method, proves to be inappropriate for high yield strength materials.

The Multi Material Arbitrary Lagrange Euler (MMALE) method is widely used method for numerical investigation of structural response under blast loading. However the method is very demanding for use at the other hand. In this paper are presented the results of the detailed numerical investigation in order to simplify some decisions contributing to the accuracy and efficiency of this model. The influence of mesh properties (particularly mesh size, its biasing and distance of the boundary (DoB) conditions from the deforming structure) on blast wave loading parameters and structural response is investigated in detail and based on the results minimum mesh design criteria is proposed. The results obtained are presented as a function of the scaled distance and additionally related to the radius of the charge. Validation studies were also done successfully.