Integrated Mobile Robotic Platform Model

Introduction. The “Smart Agroˮ committee of Research and Education Center “Engineering of the Future” has identified a number of tasks relevant for improving the efficiency of precision, soil-protecting and conservation agriculture. One of these tasks is the development of a digital multi-agent system, which provides a number of services for agricultural enterprises, developers and manufacturers of agricultural machinery. The purpose of the present study is to model an autonomous mobile robotic platform, including the development of software and hardware for trajectory control. Materials and Methods. To solve the problem, there are used modern CAx systems and their applications, the methods of 3D and full-body modeling, and the method of numerical solution of problems in solid mechanics. To expand and improve the standard functionality of CAx-systems (SolidWorks) in the software implementation of trajectory control algorithms, the methods and technologies of programming using API SolidWorks, VisualStudio C++ (MFC, ATL, COM) are used, and to build physical full-scale models ‒ Arduino and fischertechnik platforms. Results. The result of the study is a software and hardware module of trajectory control for an integrated (physical and virtual) model of a mobile robotic platform, which can be provided to the consumer as a service for technology autonomation. For the developed integrated model, control algorithms for various types of trajectories were tested. Discussion and Conclusion. The developed integrated software and hardware model of trajectory control can be used by developers and manufacturers of agricultural machinery, and directly by agro-enterprises for implementing typical technological processes. A feature of the implementation is an open hardware and software interface that provides the integration of mobile robotic platforms based on a digital multi-agent system.

Numerical Simulation of Crack Propagation of Architecture Glass Under Explosion and Impact Load

Crack initiation and propagation is a long-standing difficulty in solid mechanics, especially for elastic-brittle material. To explore the damage and crack propagation behavior of architectural glass under different type of loads, the element deletion (ED), discontinuous Galerkin peridynamics (DG-PD) and meshless peridynamics (M-PD) methods are studied. Taking the architecture glass as an example, the crack propagation behavior under the bullet impact and explosion load are studied. The JH-2 material model is used in the ED method, and the maximum principal stress and maximum principal strain failure criteria are applied at the same time. In the DG-PD method, it conducts a node separation operation and imposes the criterion of the critical energy release rate. The M-PD method adopts a self-programmed particle discretization method and imposes a criterion of critical elongation. Three methods can simulate the crack growth behavior of glass material, but the PD method has great advantages in detail, such as crack bifurcation and penetration. For low-velocity bullets, the failure behavior of glass all shows cross-shaped cracks in different methods. The splashing of elements or particles appears in the two PD methods, but the particle splashing of the M-PD method is more obvious, and the DG-PD method captures the crack bifurcation effect better. For the failure behavior of glass under explosive loading, the PD method is obviously better than the ED method in terms of modal appearance. However, in the mechanical behavior of specific elements, the two methods have a high degree of agreement.

Initial data problem for an equation related to a peridynamic model in a two-dimensional domain

В настоящей работе доказывается единственность и существование решения задачи Коши для интегро-дифференциального уравнения, связанного с перидинамической моделью механики твёрдого тела с двумя пространственными переменными. In this paper the uniqueness and existence of a solution of Cauchy problem for an integro-differential equation associated with a peridynamic model of solid mechanics in a two-dimensional domain are proved.

Assessing the Compressive and Impact Behavior of Plastic Safety Toe Caps through Computational Modelling

Toe caps are one of the most important components in safety footwear, but have a significant contribution to the weight of the shoe. Efforts have been made to replace steel toe caps by polymeric ones, since they are lighter, insulated and insensitive to magnetic fields. Nevertheless, polymeric solutions require larger volumes, which has a negative impact on the shoe’s aesthetics. Therefore, safety footwear manufacturers are pursuing the development of an easy, low-cost and reliable solution to optimize this component. In this work, a solid mechanics toolbox built in the open-source computational library, OpenFOAM®, was used to simulate two laboratory standard tests (15 kN compression and 200 J impact tests). To model the polymeric material behavior, a neo-Hookean hyper-elasto-plastic material law with J2 plastic criteria was employed. A commercially available plastic toe cap was characterized, and the collected data was used for assessment purposes. Close agreements, between experimental and simulated values, were achieved for both tests, with an approximate error of 5.4% and 6.8% for the displacement value in compression and impact test simulations, respectively. The results clearly demonstrate that the employed open-source finite volume computational models offer reliable results and can support the design of toe caps for the R&D footwear industry.

Fracture of Protective Structures from Heavy Reinforcing Cement During Interaction with High-velocity Impactor

In this work, the fracture of a reinforced concrete barrier made of heavy reinforced ce- ment is numerically simulated during normal interaction with a high-velocity titanium projectile. The projectile has the initial velocity 750 m/s. The problem of impact interaction is numerically solved by the finite element method in a three-dimensional formulation within a phenomenological framework of solid mechanics. Numerical modeling is carried out using an original EFES 2.0 software, which al- lows a straightforward parallelization of the numerical algorithm. Fracture of concrete is described by the Johnson-Holmquist model that includes the strain rate dependence of the compressive and tensile strengths of concrete. The computational algorithm takes into account the formation of discontinuities in the material and the fragmentation of bodies with the formation of new contact and free surfaces. The behavior of the projectile material is described by an elastoplastic medium. The limiting value of the plastic strain intensity is taken as a local fracture criterion for the projectile material. A detailed numerical analysis was performed to study the stress and strain dynamics of the reinforced concrete target and the effect of shock-wave processes on its fracture. The influence of reinforcement on the resistance of a heavy cement target to the penetration of a projectile has been investigated