Topological optimization of parts with lugs often yields incorrect results due to the simplified assignment of boundary conditions, such as rigid fixation or point load application, which does not correspond to the actual nature of contact interaction. The aim of this study is to develop and test a methodology that improves the accuracy and computational efficiency of modeling lugs in topology optimization problems. Based on a comparative analysis of ANSYS Workbench tools (Bear-ing Load, Remote Displacement, contact problems), it is proven that applying a distributed load of the Bearing Load type allows linear analysis results to approximate reference nonlinear contact solutions. A two-stage optimization method is proposed, wherein the first stage determines reactions in the supports, and the second stage replaces them with equivalent forces, enabling the reduction of a nonlinear problem to a linear one without significant loss of accuracy. The method is validated using examples of optimizing a manipulator link and a mechanical part with multiple lugs. The results demonstrate the high sensitivity of the final topology to the load modeling approach and confirm the practical effectiveness of the proposed method for engineering analysis, allowing for the consideration of multiple load cases with moderate computational costs.
The conditions of modern warfare form the requirements for the used and promising models of equipment. One of these requirements is a high level of mobility on the battlefield. The practical benefits of this method of protection are beyond doubt, however, its theoretical component is currently insufficiently developed. Currently known methods for evaluating the effectiveness of shooting at a moving target are limited to its speed of movement up to 25 km/h. The capabilities of high-speed tracked and wheeled vehicles exceed this speed value by several times. In connection with the above, the task of studying the effect of mobility of high-speed vehicles on security seems relevant. In order to analyze the task, the paper proposes a classification of shooting errors based on target movement. The model for determining errors when shooting at a moving target has been refined. To assess the effectiveness of mobility on security, firing errors were calculated and the probability of hitting the target with the first shot was determined, taking into account data from open sources for the main types of ground-based unguided anti-tank weapons. Such tools include modern tracked vehicles and hand-held anti-tank grenade launchers. Three main directions of target movement during combat are considered. The improved technique and the results obtained with its application confirm the effectiveness of increasing the mobility of wheeled and tracked vehicles, which contributes to the formation of requirements for ensuring the mobility of promising models of equipment.
The article presents an analysis of studies devoted to the determination of forces loading the elements of the caterpillar propulsion of agricultural vehicles. It is noted that research in recent years has been aimed at using integrated modeling, which allows taking into account the influence of systems and mechanisms that have the most significant impact on the element under study. The authors conducted virtual experiments with modeling the regime of soil digging based on the use of a simulation model. The results obtained made it possible to establish the loading characteristics of individual rollers, the values of average loads and the values of dynamic coefficients. The presented results show the importance of the functional design stage, which makes it possible to determine the values of dynamic loads acting on the mechanisms of the designed machines without expensive experimental studies.
During the operation of various critical technological equipment, in particular, energy (steam and wet steam turbines, wet steam pipelines, etc.), erosion loading of the structural elements of technological equipment is observed from the side of polydisperse droplets of moisture and solid particles of pollutants and impurities contained in the gas or air streams of the working fluid. This determines the three-phase nature of the process of erosive wear of the surface of the structural elements of the equipment. Most pollutants and impurities are hydrophilic, as a result of which relatively large solid particles are enveloped in moisture to form a liquid film on their surface, while smaller ones are suspended in the volume of droplets. This makes it impossible to easily transfer to the conditions of three-phase erosive wear the results of research and methods of forecasting either only drop-impact or only gas-abrasive erosive wear. The article presents mathematical models of mechanical and hydrodynamic processes occurring during the impact of a composite drop of moisture, i.e. droplets with a solid particle inside, with the surface of a structural element. The impact phenomenon is considered in the form of two consecutive stages. The first, initial stage involves the interaction of the surface of the structural element with the liquid phase of the composite droplet. Based on the one–dimensional ray theory, the formation and propagation of a system of reflected and refracted pressure and stress waves in an element, liquid, and particle are considered, and quantitative dependences are obtained to evaluate the characteristic parameters of processes — duration, pressures, and velocity. The second and final stage involves the interaction of the surface of the structural element with a solid eroding particle. A system of equations of motion of a particle in the process of its insertion and rebound is constructed, taking into account the action of a liquid behind the back of a solid particle. A dependence is also proposed for the quantitative calculation of the value of the erosion and fatigue damage to the microplate of the surface of the structural element from the impact of a single composite drop.
Determining the width of the load-bearing belt of a conveyor belt is one of the basic design procedures that directly affect the further synthesis of geometric parameters of the entire conveyor. During this procedure, engineers are forced to operate with a number of auxiliary coefficients, the origin and principle of application of which are quite difficult to verify simultaneously for various combinations of roller support structures and properties of transported goods, in particular, the angle of natural slope at rest and in motion. In this article, a theoretical analysis of the above combinations has been carried out and a number of performance coefficient values have been obtained in relation to the choice of the belt width, depending on the accepted model of the belt position on the roller support, taking into account the shape of the belt – parabolic or trapezoidal, as well as the proportions of the belt width in contact with the central and side rollers of the roller support. The comparison of the obtained results with the data proposed in the reference literature as reference ones is given. Recommendations are given on the choice of the performance coefficient when designing a conveyor belt.
