Ingrid Delyová

Kinematic Analysis of Mechanisms Using MSC Adams

This paper deals with kinematic analysis of a six-member mechanism. The analytical solution is based on the fundamental kinematic relations derived for this mechanism. The program MSC ADAMS was selected for the simulation modeling of mechanism. That program allows comprehensive analysis of this system using a simple modeling.

Kinematic Analysis of Crank Rocker Mechanism Using MSC Adams/View

The aim of this article is to develop a functional model of crank rocker mechanism in ADAMS/View software and subsequent complete kinematics analysis hereof. We analyze the movement of the members of the mechanism. The kinematic analysis was performed analytically and graphically. The mechanism has been modeled too and solution was drafted in the program MSC ADAMS/View. The next stage is the simulation with a set of different parameters to obtain its kinematic analysis. Finally, the data gathered in this process is compared and evaluated. Finally, the paper presents the results with graphical representation of parameters such as speed, distance and acceleration.

Influence of Material Structure and its Properties on Predicting Life of Pressure Pipelines

Pressure pipelines belong to the group of technological carrying structures that are designed in accordance with Standard Eurocode 3: STN EN 1993: Design of steel structures. These standards are used also later in the stage for assessment of failure states and fatigue life. Standard Eurocode 3: STN EN 1993-4-3 establishes the requirements for material properties of pipes and welds, associated with mechanical properties. A serious problem in estimating fatigue life of structure is the consideration of gradual degradation. The article also discusses the analysis of fatigue failure of the pressure pipeline, where it was found that the initiation of fatigue failure occurred in the area of poor weld. The further spread of the crack then occurred in the base material of the pipeline.

Operational Safety of Compressor Station Pipeline

Failure of pipeline system can endanger human lives and cause serious damage; therefore it is necessary to check it in terms of strength and life reliability. Inspection was performed on compressor station pipeline, where in terms of resistance to brittle failure it was discovered, that the weakest point of the pipeline is the weld. At lower temperatures danger of brittle failure of weld joint can arise. To assess the strength of the pipeline in investigated cross-section, with respect to state of plane stress, strength theories were applied. Values of reduced stresses were assigned based on main normal stresses resulting from experimentally set components of state of plane stress. Fatigue assessment was done, based on currently valid standards.

Distorsion of Isochromatic Fringes in the Process of Stress Measurement in Structural Part by Photoelasticimetry

Abstract In the article we show the possibility of distorting the results of the experiment by photoelasticity path, in case the isochromatic fringe patterns are recorded by the camera. The recording of the color spectrum may be distorted by inappropriate selection of the recording medium, which is reflected by different types of aberrations. Transferring a record to a computer allows you to automate the experiment process, thus saving time to work with isochromatic fringes. As an example, we present the experimental determination of the stresses of the rotor with a symmetrical arm. The analysis was performed using software developed by the authors. This software enables full automation of the experiment process. The rotor is investigated by the method of reflection photoelasticity. The experimental solution is realized as a case of periodically repeating dynamic effects, in which a stroboscopic source of white light is needed. The results of the experiment are compared with the numerical solution and their dependence is represented by diagram.

The Fatigue Fracture Caused by a Random Operating Process

The whole structures, mostly the structural nodes or elements work in time-varied stress instead of the static one. The stress concentrators are such changes of shape of mechanical part which evoke the changes of force flow. They influence the stress which loads this part. The risk of fatigue damage concerns structural components, structural knots and even whole structures subjected to random loading. This can initiate the accumulation of fatigue damage in critical points of the structure, growth and spreading of fatigue cracks and, eventually, fatigue fracture. Final failure of structural components may have fatal consequences. Damage and fatigue failure may occur due to a combination of cyclical stress and improper technology for producing a structural element, e.g. during welding. These failures are documented on the example of the holder of a crusher moving knife and of the turbine rotor shaft.

Analysis of Sandwich Structures by the FEM

The use of sandwich structures is increasing rapidly. This paper is aimed on mechanical properties of sandwich structured composites and their usage in technical practice. The main contribution in paper is realized static analysis of simple sandwiches composed from various materials of core and face sheets. Final results of analysis were fields of data about maximum stresses, displacement fields of structural points of sandwich composite.

Selection of a Significant Numerical Model of Plasticity for the Purpose of Numerical Analysis of Plastic Reinforcement

The paper is focused on the process of selecting a suitable material plasticity model. Such a model would be used in the future numerical analysis of the behaviour of selected structural elements in the elastic-plastic deformation of the steel in the SolidWorks software environment. These analyzes should include monitoring the behaviour of the material under the conditions of its plastic reinforcement (strain - hardening). Numerical modelling used two models of plasticity, namely the von Mises and Trescas models. Subsequently, a comparison of the match between the real load-deformation diagram, possibly stress-strain diagram, obtained by the experimental static tensile test and the diagram obtained from the numerical simulation of two different steel-based structural materials was performed. The results of the dual tensile test analysis showed that the von Mises model achieves greater consistency with the tensile curve based the actual tensile test. Therefore, this model will be later used in subsequent numerical simulations of the material under the conditions of its plastic reinforcement.

Applying of Stress Collectives in the Design of Structural Elements of Heavy Load-Bearing Structures

The article deals with the analytical-experimental means of determining the rate, respectively, the degree of fatigue damage for the analysis of limit state of main supporting structural element of the main beam on the twin beam of the bridge crane. Taken into account it is the dynamic effect of load hoisting and the application of load collectives and the position of the crane crab obtained experimentally for the development of stress collectives. In this analysis, the expression of the link between random load process and fatigue properties of material the Palmgren-Miner linear theory on fatigue damage accumulation was applied.

Use of FEM in Identification of Stress in Place of Concentration Factor

Stress concentrators are sudden changes of shape of mechanic part, which evoke changes of force flow, so they influence tensions, which load this part. The same goes for the static or the cyclic loading. The notches which are on the surfaces of various components increase the stress. Such kind of stress creates instability and weakening of the component. However, it is possible to reduce that influence by adding such notches which are spaced apart in some distance.