Abstract. A review of the existing methods applied to multi-criteria decision aiding has been made as well as the multi-criteria approach to a class of problems in the field of material science has been defined. The multi-criteria decision aiding has been successfully applied to determine appropriate compromise decisions about the examined parameters of a number of technological processes of welding, chemical thermal processing, iron covering, etc. The approach presented determines the values of technological factors satisfying the requirements of users simultaneously to a number of values examined and proposes a solution for the relatively highest thresholds at one and the same time
Резюме: Съобщението е свързано с двата основни подхода на проектирането /CAD-CAE анализите/, осигуряващи повишаване прага на служебните характеристики на елементи от авиационната техника, както и нейната икономичност. САЕ-изследванията се отнасят до моделиране на термо-и газодинамичните процеси, якостно-деформационното състояние на основни елементи от газотурбиния двигател-ГТД и тяхното взаимодействие, като итеративен процес при използването и прилагането на нови материали и технологии. Разработените модели са за оценка на изследваните величини от работата на ГТД, приложими при различни условия на експлоатация, с възможност за проиграване на избрани решения с изменение на входните параметри от потребителя. Обединяването на подобни методики, основани на ресурсното проектиране могат да изградят концепция за проектиране, обезпечаващо пълен ресурс при експлоатацията на изделията и високо ниво на тяхната безотказност. Докладът е методически и разглежда свойствата на обекта, чрез използване на съвременните информационни технологии и акцентът му обвързва процесът на избор на материал с конкретните индекси, наложени от схемата на натоварване. 1. Въведение Производството на високо технологични изделия в световната икономика утвърди нов информационен подход, в основата на който стои категорията "качество" . Тази категория се свързва с информацията за свойствата на обекта на изследване, използващи информационните технологии при решаването на задачите от проектирането. Съвременните газотурбинни двигатели, като високотехнологични изделия-наукоемки и технологични продукти, са аналози, които по отношение на нивото на възникващите напреженията и характерното температурно състояние при тяхната работа не се срещат сред останалите изделия в машиностроенето. Тези двигатели са твърде разпространени силови изделия, използвани в транспорта /въздушния, сухопътния, водния/ и енергетиката. По различното си предназначение газотурбинните двигатели се различават помежду си главно по условията на работа, Механика ISSN 1312-3823 (print) Транспорт ISSN 2367-6620 (online)
The paper presents the results of studies of tribological properties of the contact of the tool steel composition Fe-18W-4Cr-1,2V with the magnesium alloy AZ91D strengthened by submicron powder filling out of SiC and severe plastic deformation (SPD), namely equal-channel angular pressing (ECAP). It is stated that introduction of SiC powder filling to the magnesium alloy the friction coefficient on the moving frictional contact increases, the wear rate reduces. These tribotecnical characteristics are influenced by the size and volume of the particles of powder filling, normal loading force and slip rate. SPD of the initial material results in reduction of the adhesion constituent of the friction coefficient. Introduction In modern mechanical engineering, in particular in friction knots, one of the ways to reduce the weight of cars is to apply light alloys with enhanced mechanical properties. Magnesium is attractive to be applied as structural material due to attractive strength-to-weight ratio that exceeds the one for aluminum and other light metals and alloys [1-3]. High damping capacity of magnesium alloys allows using them effectively to manufacture automobile and aircraft wheels, various components for motor-and-tractor and aerospace engineering, rollers for cargo conveyors [6, 7] etc. The strength of magnesium could be enhanced without significant change in the strength due to addition of small amount of submicron powder filling of SiC [3-5]. Besides, severe plastic deformation is known to effectively increase the strength of bulk metals due to fabrication of ultrafine-grained structure [8, 9]. SPD techniques can be considered as alternative techniques to dispersion strengthening of composite materials. However, tribological behavior of these materials is studied insufficiently for application in friction knots [10, 11]. In this paper the results of definition of wear rate of the magnesium alloy, the friction coefficient and its molecular constituent depending on the content of the powder filling are given. Comparative evaluation of the adhesive bond shear strength and molecular constituent of the friction coefficient of the magnesium alloy AZ91D strengthened by ECAP in the slipping tribological contact with the tool steel composition Fe-18W-4Cr-1,2V is presented.
Annotation: The paper presents the results of numerical modeling of the conventional drawing and free torsion processes of rods made of low-carbon steel using the "DEFORM-3D" software package. The heterogeneity of the strain intensity distribution in the investigated processes revealed in the model basically corresponds to real physical experiments with similar parameters of the structural heterogeneity. A mutual correspondence of the ductility diagram to the character of the structural changes in the samples deformed by free torsion is established, and the limiting values of the ductility margin, the excess of which leads to the development of fracture processes.
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The paper presents standard statistical procedures for determining expert assessments for the influence of magnesium alloy components on the controlled mechanical properties: tensile strength and relative elongation. There are obtained neural models describing mechanical characteristics from the amount of aluminum, manganese, nickel, iron and silicon directly related to the exploitation properties of the product. The applied approach makes it possible to determine of compositions ensuring relatively optimal values of the explored quality indicators.
The achieved results give grounds for future active international cooperation with scientific and production institutions for which a specific scientific product has been created and tested. The elaborated scientific product is a set of numerical methods beyond the scope of the originally intended application only for metallurgical and metalworking production. The developed methods are evaluated with the benefits of the relevant area. In the references, results have been achieved for saving materials and energy while maintaining the same level of quality indicator. This also indirectly reflects on the environmental protection. The importance of my research has been underpinned by the universality of the approach, and it has been developed for models of regression analysis and the artificial neural networks. Thus, a valuable and up-to-date methodology, thoroughly endorsed in a scientific style, has been apportioned and implemented
The offer presented demonstrates the advantages and possibilities of a specialized software product for multi-criteria and multi-parameter aid with making decisions based on the method of movable limitations. This method has been considerably applied with developing a number of technology processes in the machine manufacturing production in order to determine the combinations of control factors satisfying the requirements given beforehand by a decision maker (DM). All examples examined are summarized in Previous Studies Section
The paper presents optimization decisions for plazma platings properties in dependence on the processing mode parameters. For that purpose, multicriteria optimization is applied. The presented results are initial proof of applicability of this approach in metallurgy .
Abstract: The paper presents the application of modern computational approaches in determining the appropriate chemical composition of titanium alloys . Discusses three types of problems for the selection of the chemical composition of alloy at set requirements for mechanical properties . Tasks are solved in a different formulation of the target criteria . The proposed solutions are based on software model using approximation with artificial neural networks and genetic optimization algorithm.
Abstract: An algorithm for numerical analysis of multi-parametric regression models is introduced. It is intended for software realization mainly to offer an user-friendly environment for analysis, appropriate to/related to future multi-criteria optimization. The analysis is performed via visualizing various fragments from the domain supported by different tools and editors. The definition of the algorithm is followed by a test sample for analysis in the distribution of hardness of ion nitriding instrumentation, class heat resistant steel.
In this paper we present two methods for solving nonlinear MCDM problems. Their philosophy arises from the internal nature of application problem that we are solving by using such MCDM model. Namely, to solve problems for building-up by welding. The first method is non-interactive apriori method. The second method is interactive learning-oriеnted method based on reservation levels. 1. INTRODUCTION The basic problem in the process of design, control and planning of functioning engineering systems is the determination of the system structure, the material and power balances, the dimensionality of the equipment, the controlling variables in normal and emergency modes of system operation and also of production planning for short-term / long-term exploitation – , . The solution of this problem must be found under the restrictions of different requirements postulated by economic (minimization of material and power consumption, maximization the profit from the production), technical (minimization of the equipment size), ecological (minimal pollution of the environment by a specific waste product) and other specifications. It is evident that the requirements cannot be satisfied as a whole but a reasonable compromise is a solution of the problem. In fact this is a multicriteria model for solving such problems.
Abstract. The paper presents the methods developed to determine the capacity of mechanical processing of plane-loaded layers under the conditions of electric arc welding in a gas mixture. The methods were applied after the experimental investigation and working out of the regression dependencies of the surface geometry welded with electrode wire providing big stiffness and difficult mechanical processing. The paper presents also some results concerning the capacity of mechanical processing with technological welding regimes of high productivity. Key words: building-up by welding, welding regimes of high productivity
(2008), Modeling of problems of metal building – up by welding with multiple criteria, IIT/WP – 247, pp. 1 – 7.
The report presents an approach for determining the influence of the technological casting parameters (temperature of the molten metal, the time between two casting cycles, and counter-pressure) on microstructural characteristic DAS. The study was carried out on six different sections of interest of the aluminum casting volume with regard to the performance of the product. As a result of the applied multi procedure parameters of casting regime are defined providing simultaneous minimum values of microstructure parameter in the studied sections which is an indicator of the quality of the product. The contribution of the study is to confirm new funds known for foundry science and practice.
A review of the existing methods applied to multi-criteria decision aiding has been made as well as the multi-criteria approach to a class of problems in the field of material science has been defined. The multi-criteria decision aiding has been successfully applied to determine appropriate compromise decisions about the examined parameters of a number of technological processes of welding, chemical thermal processing, iron covering, etc. The approach presented determines the values of technological factors satisfying the requirements of users simultaneously to a number of values examined and proposes a solution for the relatively highest thresholds at one and the same time.. 1. INTRODUCTION The modern problems of examining the parameters of new and conventional materials and technological processes are multi-criterial and conflict in principle. This nature of the problems is grounded by the fact that, with there examination, it is necessary to provide a certain set of parameters that have to satisfy users' requirements. The solution sought usually consists in determining those combinations of controlling parameters that provide the set of quality parameters specified. The choice of the assessment system of criteria and their rating according to the degree of significance is a problem difficult to formalize. It does not have unambiguous interpretation inevitably causes subjective decisions. The problem of multi-criteria decision aiding could be most generally defined as a process with:-a great number of parameters of the solution with a complex interaction among themselves;-complex cause-and-consequence relations of the solution parameters and the attributes or aims;-a set of alternatives, which could be reduced to a limited number and in this case the form of cause-and-consequence has to be used. Due to that reason, looking for an appropriate model to solve a certain multi-criteria problem, one should define first the type of the situation, which is most suitable for solving the problem. An important element of the information base is the component implementing the method of planning the experiment. The main instrument and means of the modern scientific technologies is modeling as by it one can formulate the multi-criteria problem. The models of the complex objects and phenomena are often integrated including contents-describing and formal mathematical parts. The " model " is most often understood as a population of key (substantial, controlling) variables and their logical and physical connection allowing a consistent description of the system properties. In the field of material science the subjects examined are the processes changing the structure of materials on the purpose of accumulating knowledge on them and determining the field of its application. Hence, the study mainly emphasizes on different indices of quality providing including the following groups of criteria: strength (with static and dynamic loading), stiffness (E-module) and toughness (of the material/article), wear-out resistance and
KeyWords: Transport equipment, transport engineering, principles of Altshuller Abstract: Solving inventive tasks and finding new more rational decisions is a current task, which covers all areas of activity in modern life. The new and more correct solutions can be used both in the methodology of educational training and in our daily scientific and technical practice. This paper deals with the manifestation of the Theory for Solving Inventive Tasks (TRIZ) of Altschuller in the field of transport equipment. The carried out analysis in the paper shows that the proper development of transport engineering can be ensured only when this development is in line with the established logical system and when there have been applied sound logical principles. Some of the newest technological solutions are analyzed in the field of transport engineering and the manifestation in them of the principles of the Altschuller logical system.