The objective of this study is to present a numerical modeling of mixed-mode fracture in isotropic functionally graded materials (FGMs), under mechanical and thermal loading conditions. In this paper, a modified displacement extrapolation technique (DET) was proposed to calculate the stress intensity factor (SIFs) for isotropic FGMs. Using the Ansys Parametric Design Language APDL, the continuous variations of the material properties are incorporated by specified parameters at the centroid of each element. Three numerical examples are presented to evaluate the accuracy of SIFs calculated by the proposed method. Comparisons have been made between the SIFs predicted by the DET and the available reference solutions in the current literature. A good agreement is obtained between the results of the DET and the reference solutions.
In the industrial sectors, pipelines have been used as the most economical and safe means of transporting oil and gas (Pipelines). However, the number of accidents has increased considerably as their use has increased. As a result of the operating load and the pressure used, the thickness of the tube must be increased and the mechanical characteristics improved. This approach was applied to predict the growth of crack effect in samples of two pipelines at given thicknesses and pressures. We created cracks with deferential dimensions in both API X80 steel pipelines, with an application of deferential internal pressures. For the simulations, we used the code ANSYS.
Aluminum alloy is a very useful material in light manufacturing. Friction stir welding (FSW) is a solid state assembly process that is achievable for this material. This work aims to characterize the quality of the weld joint by an operation of shaping (folding), it aims to study the rate of elastic return in this weld joint after a folding operation. In this context, the elastic return for the folding process has been modeled using experimental tests under optimal welding conditions.
In this work the structure and properties of composite rollers with surface layer made of hard alloy were studied. The rollers were made by the powder metallurgy method with sintering during pressing and the presence of a certain liquid phase during sintering (semi-liquid sintering). WC-Co and TiC-Ni-Fe materials were used as hard alloys. Iron-carbon and iron-nickel materials were used as soft base. All of the composite layers were formed in one process. The structure of base materials and border layer of these composites were studied. Investigations of thermocycling sustainability of these composite samples were carried out.
The paper presents the use of Taguchi method to optimize the cutting of stainless steel by Abrasive Water Jet. Shown are the influence of the most important machining parameters, such a traverse speed, abrasive grains size and concentration of abrasive in the jet on the maximum depth of cut. Analysis of variance - ANOVA was used to determine the effect of machining parameters on the cutting depth. Based on the calculated signal/noise ratios for individual parameters of the cutting process, their impact on cutting depth was determined and optimal process conditions were determined in order to reach the maximum depth of cut. The empirical verification of this process was also performed by comparing the depth of cut predicted and achieved in the tests.
The study defines the concept of e-larning and presents the requirements for conducting an effective course to achieve the assumed learning outcomes. As an element of the introduction to the subject, the advantages and disadvantages of e-learning resulting from the experience over the years of organizations that used or continue to use such forms of teaching are presented. The research part presents the results of research carried out in a deliberately selected group of academic teachers and a group of students. The research results presented and discussed include such aspects as: expectations, advantages, disadvantages, fit, convergence of opinions and proposals for improvement of classes conducted in the e-learning mode in the field of Safety and Health at Work. The study is completed by conclusions and proposals of utilitarian solutions in the field of conducting academic education for selected subjects in a fixed time dimension in the form of e-learning.
The approach of this paper was to analyze the technical borders of industrial robots and to provide an overview of current technology, technical constraints and the potential types of future research suggestion concerning robotic machining. These complex automation machines used in manufacturing processes are an emerging chapter of industrial engineering that contribute to automatically performing operation in subtractive manufacturing and sheet metal forming processes. Compared with CNC machines which have shape limitations and have the restricted working area, the industrial robot is a flexible, cost-saving alternative.
Cardiac arrhythmias occur frequently in valvular patients. In valvular patients the role of echocardiography is essential, due to prognostic variations. A common indication of CT coronarography is the evaluation of the coronary arteries, with the highlighting of the light coronary plaques, but also accurately measures the dimensions of the left atrium and the anatomy of the pulmonary veins. In the last years cardiac MRI (magnetic resonance imaging) has been used in the clinic and research media to establish the gold standard measurement for the volumes of heart cavities, their function and tissue structure. All these three methods are essential for the evaluation and treatment of the cardiac patient with important arrhythmia.