MODELING THE ACTION OF THE SHOCK-WAVE LOAD ON THE HULLS ELEMENTS OF 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

Bifurcation Analysis and Nonlinear Dynamics of a Capacitive Energy Harvester in the Vicinity of the Primary and Secondary Resonances

The impetus of the present study is to examine the effect of nonlinearity on the efficiency enhancement of a capacitive energy harvester. The model consists of a cantilever microbeam underneath which there is an electret layer with a surface voltage, which is responsible for the driving energy. The packaged device is exposed to unwanted harmonic mechanical excitation. The microbeam undergoes mechanical vibration and accordingly the energy is harvested throughout the output circuit. The dynamic formulation accounts for nonlinear curvature, inertia, and nonlinear electrostatic force. The efficiency of the device in the vicinity of the primary and super-harmonic resonances is examined and accordingly the output power is evaluated. Bifurcation analysis is carried out on the dynamics of the system by detecting the bifurcations in the frequency domain and diagnosing their types. One of the challenging issues in the design and analysis of energy harvesting devices is to broaden the bandwidth so that more frequencies are accommodated within the amplification region. In this study the effect of the nonlinearity on the bandwidth broadening, as well as efficiency improvement of the device, is studied.

CREATION OF MATHEMATICAL AND COMPUTER MODELS OF THE DYNAMICS OF FLAME PROPAGATION OF AIR-SUSPENDED SOLIDS IN VARIOUS ROCKS USING MATLAB ENVIRONMENT

The propagation of transient, air-suspended solids in a vented explosion chamber is numerically investigated by a dynamic formulation for the Concentration Limit of Flame Propagation (CLFP) with the GUI MATLAB environment. The geomechanics is modeled by a one-step overall reaction, which simulates the reaction of a stoichiometric propane– air-suspended solids. The CLFP modeling in the reaction rate model is numerically employed with mathematical models on basis Antoine's equation. This is based on an empirical correlation of the velocity fluctuations and implemented as interface with input-output data with graphic realization. The computer modeling show that the dynamic CLFP models provide superior results as general implementation of physical process of flame propagation and could be used for different rocks (f.e. granite, limestone, sandstone etc).