At the stage of design research of armored bodies of lightly armored vehicles it is extremely important to determine the range of their natural frequencies and natural forms of oscillation. For this purpose, the finite element method is usually used. It is necessary to substantiate the parameters of the finite element model, which provide an acceptable level of accuracy of numerical modeling of dynamic properties of this type of structures. For this purpose, data from parallel numerical and experimental studies of the mock-up of the armored hull of the armored personnel carrier are used. The mock-up of the upper projection of the armored hull is made in the appropriate scale. The material is sheet steel. This mock-up is subjected to dynamic excitation on a vibrating table. Resonant excitation frequencies are recorded, as well as the natural vibration forms. Shock-pulse excitation of the armored hull’s mock-up was also performed. The response to this excitation is recorded using accelerometers. Then, the spectrum of natural vibration frequencies is determined from these oscillograms. In parallel, numerical modeling of natural frequencies and natural vibration forms of the armored hull’s mock-up is carried out. After that, the results of numerical and experimental studies are compared. By varying the parameters of the finite element model, a satisfactory correspondence between the results of numerical calculations and experimental measurements is achieved. In particular, the following are determined: the acceptable type of used finite elements; the number of finite elements required to satisfy the accuracy of numerical modeling of the dynamic properties of similar structures; zones of the recommended thickening-rarefaction of a grid of finite elements, etc. According to the research results, the parameters of finite-element models have been established, which can be used to study the dynamic processes and properties of full-scale armored hulls of lightly armored vehicles. Keywords: lightly armored vehicle, mock-up, natural frequency, spectrum of natural vibration frequencies

The work describes a general approach to dynamic processes modeling under action of pulsed reactive forces of recoil during firing shots from combat modules weapons. The combat module can be presented as a discrete system; this approach also applies to elements of drive, engine, transmission, etc. They are characterized by a local compact concentration of mass and high rigidity of the structure itself compared to the same armored hull or special elastic elements of suspension system. Then the reaction of this complex mechanical system to the action of dynamic forces is of interest. On the basis of the developed approach to analysis of the dynamic response of the combat module of a lightly armored vehicle equipped with a small-caliber automatic gun to the action of reactive recoil forces, it is proposed to carry out a qualitative analysis on simplified models at the first stage. The influence of a single shot and burst firing on the deviation of the axis of the barrel from the direction to the target is analyzed. For this, a simplified test model was built. Further, on the obtained simplified models, the results are compared with the results of the analysis on more complex models. The introduced piecewise linear approximation dependence of the time distribution of the reactive recoil force makes it possible to parametrize such force distribution with one parameter. As evidenced by the research results, the nature of the response of the studied dynamic system is strongly influenced by the damping level. If the damping level is high, and the frequency of the pulses is not a multiple of the natural oscillations frequency then the influence of individual pulses can be considered in isolation from each other. The characteristic features of the transient and stable modes of movement of lightly armored vehicles combat modules are determined. These qualitative features determine the nature of the response of the dynamic system to the action of a single pulse and to the action of a series of such pulses. The same features are also characteristic of systems with a large number of degrees of freedom, as well as systems with distributed parameters. Keywords: dynamic system, combat module, lightly armored vehicle, transition process, steady process, integration of differential equations system, reactive recoil forces during firing shots

In order to substantiate the advanced technical solutions of radial hydrovolume transmissions, it is necessary to study the stress-strain state of their most responsible and loaded elements. In particular, it is of interest to determine the rational parameters of cylinder block, which is subject to significant pressure of working fluid. This leads to the formation of a stress-strain state with a high level of stresses and elastic displacements. They can be dangerous in terms of strength, rigidity and performance of the hydraulic transmission in general. To carry out numerical studies of the stress-strain state of cylinder block of hydrovolume transmission at the design stage, finite element models with varied parameters are developed. However, at this stage of research, it is desirable to have a verified numerical model. For this purpose, the paper describes the computational and experimental studies of the layout of the cyclic part of the hydrovolume transmission cylinder block. On the one hand, these studies were performed using the experimental method of holographic interferometry. On the other hand, calculations were performed using the finite element method. In the course of comparison of the received results, the finite element model parameters are determined which provide high accuracy of the stress-strain state calculation of hydrovolume transmissions cylinder block. Keywords: stress-strain state; hydrovolume transmission; finite element method; cylinder block

The paper describes studies of breakthrough methods effectiveness for sharply increasing the resource of highly loaded military and civilian vehicles elements based on methods of their discreetly continual strengthening. These methods, unlike traditional ones, combine the advantages of discrete and continual strengthening methods and lack their main disadvantages. The analysis of contact interaction of representative structures of contacting bodies at the microlevel is carried out. They consist of fragments of contacting parts, one of which is strengthened continually, and the other part is strengthened discretely. At contact interaction at the microlevel, on the one hand, the effects of the nanоlevel are manifested, and on the other hand, the effects of the macrolevel are manifested too. Nanoeffects are the redistribution of contact forces between bodies: from smooth ones they turn into an archipelago of hilly elevations. Macroeffects are to adapt the shape of the contact parts to the distribution of contact forces, smoothing their overall unevenness. As a result, the overall effect of strengthening is achieved, increasing the strength, load capacity and resource of military and civilian vehicles elements. A breakthrough is being achieved in improving the performance of military and civilian vehicles, which corresponds to or exceeds the world level for similar products. Keywords: discrete strengthening; continual strengthening; discreetly continual strengthening; contact interaction; military and civilian vehicles

To study the effect of shock wave load on the body elements of vehicles, a setting has been developed that takes into account the mobile nature of this load. A specialized parametric finite-element model of the body layout has been created armored-carrier, taking into account the peculiarities of the studied process. The problem of determining the stress-strain state armored-hulls solved in static and dynamic formulation. The space-time distributions of components and characteristics of the stress-strain state of the investigated model armored-carrier of armored hulls are given. The results of research in the used formulations indicate the need to solve the problem in a complete dynamic formulation with account for plastic deformations. This  establishes a new methodology for the rational choice of engineering solutions. Keywords: stress-strain state; armored carrier; armored hulls; shock wave; moving load; sample; rational constructive decision