Papers by Keyword: Contact

Abstract: The contact between the original and the new concrete layer is important from the point of view of the load-bearing capacity of the composite cross-section. In practice, we encounter that when reinforcing a concrete element with a new layer of concrete, the element is considered as a single cross-section, so no slippage between the individual layers is assumed. This article deals with numerical modeling of two contact variants. The first alternative is modeling according to the im-plemented module which contains the 3D program ATENA Cervenka Consulting and the second is using an intermediate layer and subsequent comparison of modeling methods with a real experiment.

Abstract: The simulation of load application elements requires the modeling of the contact point and a nonlinear analysis. This contact analysis is still time-consuming despite of powerful computers. A reduction of this contact by a simple load model would result in enormous time savings. The Hertzian contact theory provides an analytical approach to the contact problem. However, an isotropic material behavior is assumed, which is problematic especially with fiber reinforced structures. Nevertheless, a suitable load model can be developed for a simplified model of a bolt joint. The edge effects occurring at the edge of the hole are determined using an approximation function (parameterized polynomial approach). The anisotropic material behavior is represented by alternative models or it can also be integrated into the calculation by an extension of Hertzian theory. The different approaches are compared in respect of accuracy, complexity and computing time. For reference and verification of the results, a contact model is created using the FEM software HyperMesh and Optistruct from Altair. Besides the contact model can be used as an aid for creating the load model. Finally, a method is presented, which reduces a contact analysis to a purely linear static structural analysis and thus enables a significantly reduced computing time. The corresponding load model also gives a good representation of reality.

Abstract: Scientists and sport athletes are constantly seeking for the methods which could improve surface sliding ability on ice. Modifications of contact area and surface roughness are relatively easy but not yet fully understood methods for sliding ability improvements. This research contains information of how one can perform on-field experiments with skeleton sleigh to determine the influence of surface contact area and roughness on sliding ability. Two types of surface roughness i.e. polished (3000 grain sandpaper) and scratched (600 grain sandpaper) are compared using three different contact areas. Obtained data showed that rougher surfaces tend to slide faster if contact area is larger but the effect reverses if contact area is reduced.

Abstract: The analysis of properties of the antifriction materials suitable for use as materials of a surface of sliding of contact nodes was made and the elastoplastic model for the description of their behavior has been chosen in the work. The general mathematical statement of the problem of friction contact interaction of two elastic bodies through an elastoplastic antifriction layer taking into account all types of a contact state has been made. Check of mathematical statement within numerical realization of an experiment on uniaxial compression of a sample by press plates taking into account friction on the interfaced surfaces has been executed. Assessment of convergence of the numerical solution of the task of contact parameters depending on a number of nodal unknowns has been made, optimum finite element decomposition of the model has been chosen. It has been established that the numerical solution gives a good quantitative capability to results of a natural experiment. It has been established that all paths of deformation have small curvature in all considered points of the polymeric cylindrical sample.

Abstract: The biomechanical behavior of the protective constructions materials within the framework numerical modeling of the contact interaction problems is considered in the work. Assessment of the numerical solution convergence of problem from extent of the system discretization is performed within the framework of the study, the optimum size of the finite element in the contact region is chosen. Assessment of the contact zone parameters without and with friction on the interfaced surfaces is performed on the model problems of contact between the tooth-indenter and the half-space of EVA and with a half-space of EVA containing a layer of A-silicone. The investigation of the deformation behavior of the contact node consisting of a three-layered kappa and two tooth-indenters is performed: the distribution fields of the contact parameters depending on the indentation force were obtained and analyzed, zones of contact states change are revealed, stress-strain state of the structure as a whole is considered.

Abstract: The article deals with the experimental investigation of cutting conditions from the view of force load during machining high alloyed tool steel EŠ 419556 (standard by Škoda a.s. Pilsen, based on DIN 1.2326) at high speed milling. The aim of presented research is investigation of the most favourable contact and cutting conditions to minimize the power load of the cutting edge. Processing of measurement results within presented investigation was focused only on the components of cutting force F_C (tangent) and F_CN (normal) that adequately characterize the cutting process. The experiments were also carried out at cutting depth (a_p) changing during high speed milling. The obtained results are presented in the paper by means of graphs that clearly show the behaviour of cutting force components at given conditions.

Abstract: The ANSYS® Finite Element Method (FEM) program offers a variety of elements designed to treat cases of changing mechanical contact between the parts of an assembly or between different faces of a single part. These elements range from simple, limited idealizations to complex and sophisticated, general purpose algorithms. Contact problems are highly nonlinear and require significant computer resources to solve. Recently, analysts and designers have begun to use numerical simulation alone as an acceptable mean of validation employing numerical Finite Element Method (FEM). Contact problems fall into two general classes: rigid-to-flexible and flexible-to-flexible. In general, any time a soft material comes in contact with a hard material, the problem may be assumed to be rigid-to-flexible. The other class, flexible-to-flexible, is the more common type. To model a contact problem, you first need to identify the parts to be analyzed for their possible interaction. If one of the interactions is at a point, the corresponding component of your model is a node. If one of the interactions is at a surface, the corresponding component of your model is an element. The finite element model recognizes possible contact pairs by the presence of specific contact elements. These contact elements are overlaid on the parts of the model that are being analyzed for interaction. This paper present a simulation contact friction between Two Rock bodies loaded under two types of load condition: Axial pressure Load “σ” and Tangential Load “τ”. ANSYS® software has been used to perform the numerical calculation in this paper.

Abstract: The sense of stability during vehicle braking is largely related to brake performance. Among the brake parts, the brake pad must be working properly to ensure the braking performance and stability of the vehicle. That is, brake pads are required to maintain a uniform pressure distribution during braking. In addition, brake pads must maintain a proper braking force during rapid increases in temperature. In this study, the three-dimensional finite element (FE) model was developed to determine the distribution of the contact pressure of the brake pad. The temperature distribution on the pad surface was confirmed. The sensitivity to changes in material properties was verified using the developed model. Pad wear due to friction can be predicted by confirming the thickness variation due to heat. A fully coupled thermo-mechanical analysis of the developed FE model was performed using ABAQUS.

Abstract: The analysis of the sliding contact behavior for friction lining is an important issue in design of centrifugal clutches. In this study, a numerical model based on the moment equilibrium and contact mechanics has been developed to analyze the dynamics of a commercial centrifugal clutch. The proposed dynamic model can estimate the rotational speed of initial contact, output torque, and contact pressure for friction lining during the clutch operation. The comparison of the numerical and experimental results for the output torque of the analyzed centrifugal clutch shows the simulation agrees well with the experimental data. The difference for the maximum output torque is around 1.9%, which shows the effectiveness of the proposed method. The proposed dynamic model can reduce unnecessary physical prototypes and experimental cost, and is expected to be used to improve the design of the centrifugal clutches.

Abstract: Innovative materials and structures are analyzed in this paper. On the basis of provisions of the systems analysis the principles and approaches to modeling of processes of contact and condensation curing of silicate materials are developed. The mechanism of contact and condensation process on macro - and mesolevels of system is presented. There are provisions of synergetic at its base: formation of an infinite cluster of a framework of a raw from the power links connected by a contact condensation crossing point as a result of redistribution of an unstable phase calcium-silicate knitting between sources and drains of structure-forming elements. Theoretical modeling of intergrain condensation at the base of which there are submodels of the squeezed deposit and a capillary porous body is executed. The nanosized filler has a polyfunctional influence on the structure and properties of calcium-silicate and cement materials, takes part in the formation of new chemical compounds and the structure of pore walls.