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1
Content available remote Wpływ rozwiązania ściany zewnętrznej na rozkłady temperatur w przegrodzie
Małek M. T., Koczyk H.
Czasopismo Inżynierii Lądowej, Środowiska i Architektury / Journal of Civil Engineering, Environment and Architecture
|
2016
|
z. 63, nr 3
247--254
PL
W referacie porównano rozkład temperatur w przegrodach zewnętrznych bez oraz z barierą termiczną zlokalizowanymi w II strefie klimatycznej z projektową temperaturą zewnętrzną wynoszącą -18°C oraz temperaturą wewnętrzną w pomieszczeniu równą 20°C. Do analiz przyjęto ścianę zewnętrzną o konstrukcji betonowej zaizolowa ną z obu stron styropianem. W przypadku przegrody z barierą termiczną, utworzono barierę za pomocą polipropylenowych przewodów wypełnionych niskotemperaturowym czynnikiem zawartych centralnie w warstwie betonu. W obliczeniach wariantowano temperaturę otoczenia zewnętrznego oraz temperaturę bariery termicznej, przy czym temperaturę wewnętrzną w pomieszczeniu latem przyjęto równą 24°C, a w pozostałych miesiącach 20°C. Do symulacji przepływu ciepła w przegrodzie posłużono się jedną z metod numerycznych, metodą bilansów elementarnych, która opiera się na podziale rozpatrywanego elementu na podobszary i określeniu temperatur na końcu kroku czasowego. Zastosowaną metodę opisano krok po kroku, prezentując jednocześnie tok obliczeń dotyczących analizowanych wariantów. Równania temperatur w komórkach bilansowych dla odpowiednich warunków brzegowych zestawiono w formie tabelarycznej. Wspomagająco posłużono się modelem utworzonym w programie MS Excel, dla którego wykonano obliczenia iteracyjne z krokiem czasowym równym 5 s. Otrzymane rezultaty zaprezentowano w postaci rozkładu temperatury. Na ich podstawie stwierdzono np. w warunkach obliczeniowych przesunięcie izotermy 0°C w kierunku środowiska zewnętrznego oraz większą temperaturę w pomieszczeniu na powierzchni przegrody dla rozwiązania z barierą termiczną w porównaniu do wariantu klasycznego. Czynniki te wpływają na zmniejszenie ryzyka wystąpienia wykroplenia wewnątrz przegrody oraz odczucia nagłego spadku temperatury w pobliżu ścian zewnętrznych, a także podwyższenia temperatury odczuwalnej w pomieszczeniu.
EN
The paper shows the distribution of thermal gradient in the external walls with the thermal barrier and without the thermal barrier. The walls construction are made with the concrete and the polystyrene on the both sides. The thermal barrier are the polipropylene tubes filled by the low temperature medium. The calculations are prepared for two variants. One of them used the external temperature equals -18°C (the II climatic zone), the internal temperature in a room equals 20°C and the temperature of the thermal barrier equals to 18°C. The second used the internal temperature in a room equals 24°C (in summer), 20°C (in others months) and the mean monthly temperature. For the purpose to simulate the heat transfer in the wall are used one of the numerical methods, by elemental balances, which is based on a division of the element into sub-areas and determining the temperature at the end of the time step. To support the calculations it was prepared the spreadsheet in MS Excel , for which calculations were performed iteratively with a time step equal to 5 s for both walls. The results obtained are presented in the form of a thermal gradient. The isotherm 0°C was displaced towards to the external environment and the higher temperature at the surface of the wall in the room for the solutions with the thermal barrier compared to the classical variant. These factors affect the reduction of the risk of condensation inside constructions and feeling that the temperature falls near the external walls.
2
Content available remote Preliminary analysis of a innovative type of low pressure valves
Klarecki K.
Journal of Achievements in Materials and Manufacturing Engineering
|
2010
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Vol. 41, nr 1-2
131-139
EN
Purpose: Presentation and analysis of the innovative type of a direct operated low pressure relief valves. Design/methodology/approach: In this paper was presented a proposal of a improvement of a new low pressure relief valve. The advantages and disadvantages of this valve was estimated by numerical simulation with MATLAB/SIMULINK aid. Findings: Main advantages of presented relief valve are: high precision of the operating pressure and short time responses, the disadvantage of the modelled valve is the high value of the peak pressures. Research limitations/implications: The expected next stage of valve research is the experimental tests. For that purpose one should the prototype of valve build. Practical implications: Presented low pressure relief valve can be used in low pressure hydraulic system, for example for feeding of the hydrostatic or hydrodynamic bearings. Originality/value: Original value of this paper is a idea of low pressure relief valve.
3
Content available remote Numerical and experimental analysis of spine’s transpedicular stabilizer
Kiel M., Marciniak J., Basiaga M., Szewczenko J., Kus W., Kokot G., Wadek T.
Journal of Achievements in Materials and Manufacturing Engineering
|
2010
|
Vol. 41, nr 1-2
124-130
EN
Purpose: The aim of the work was a numerical and experimental analysis of spine’s transpedicular stabilizer on lumbar part of spine. The result of the analysis was determination of displacements of the stabilizers’ elements. Design/methodology/approach: To define numerical characteristic of the lumbar spine – transpedicular spine stabilizer system, the finite element method was applied. Geometrical models of lumbar part of spine and transpedicular stabilizer were discretized by SOLID95 element. The boundary conditions imitating phenomena in real system with appropriate accuracy were established. The experimental analysis was carried out for spine’s transpedicular stabilizers which were implanted on lumbar part of pig spine. The analysis was realized by means of testing machine MTS Insight with the use of videoextensometer. Numerical and experimental analysis were carried out for stabilizer made of stainless steel Cr-Ni-Mo. System was loaded by uniaxial compression with forces from 50 N to 1600 N. Findings: The result of analysis was calculation of relative displacements of the transpedicular stabilizer in a function of the applied loading; F = 700 - 1600 N for numerical model and F = 50 - 1600 N for experimental model. Research limitations/implications: The results of numerical analysis for transpedicular stabilizer obtained by finite element method were used to determine a construction features of the stabilizer, and to select mechanical properties of metallic biomaterial. The calculation of displacements for stabilizer show that the proposed type of stabilizer enables correct stabilization of spine. Practical implications: Both results of numerical and experimental analysis showed correct selection of mechanical properties of metallic biomaterial which were used to made the proposed type of transpedicular stabilizer. Originality/value: Advantageous results of analysis showed that the type of stabilizer may be used in clinical practice.
4
Content available remote Life and operational safety of power systems and chemical plants
Okrajni J.
Journal of Achievements in Materials and Manufacturing Engineering
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2010
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Vol. 43, nr 1
38-63
EN
Purpose: The problem addressed in the paper is the description of an effort and durability of components under the conditions of mechanical and thermal interactions. The problems of proper material testing methods have been shown as the important part of the components life assessment methodology. Design/methodology/approach: The FEM modelling has been used to determine the stress and strain fields in the components and to describe their behaviour under mechanical and thermal loading. Findings: An appropriate models description has been developed. So far, experimental verification of the usefulness of the model description to determine the stress and strain patterns in particular object and for chosen operation conditions has been made. Research limitations/implications: The developed description should be useful in problems of behaviour predictions of high temperature components and their durability assessment under different mechanical and thermal loadings in industry practical applications. Originality/value: The method, which more precise description of power industry components behaviour makes possible have been shown in the work. The work is addressed to researchers interested in problems of component behaviour prediction under different loadings that we can meet in the operation practice and to power industry engineering maintenance staff.
5
Content available remote FEM used in improvement of quality of medical devices
Ziębowicz B., Ziębowicz A., Szkodny J.
Journal of Achievements in Materials and Manufacturing Engineering
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2010
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Vol. 41, nr 1-2
172-179
EN
Purpose: The fundamental aim of this research was to determine the biomechanical characteristics of the medical bed made of carbon steel and an assessment of its stability. To define the biomechanical characteristics of the bed design, the finite element method (FEM) was applied. Additionally, the risk analysis was conducted according to the directives of ISO 14971 standard. Design/methodology/approach: The research was carried out on the typical rehabilitation bed. To define the biomechanical characteristics of this equipment, the finite element method was applied. Geometric model of medical bed, was discretized by means of SOLID 95 element. Appropriate boundary conditions imitating phenomena in the real system with appropriate accuracy were established. The aim of biomechanical analysis was calculation of displacements and stresses in the bed’s construction elements in a function of the applied loading. In order to carry out calculations, 3 models of diverse variants of loading were selected – safe working load - model 1, transverse stability - model 2 and longitudinal stability - model 3. Findings: The analyses showed the difference in displacements, strains and stresses in the characteristic points depending on the selected loading. That also helped to determine maximal loading causing the exceeding of the yield stress of the bed’s components. Research limitations/implications: The limitations were connected with simplification of numerical model of femur as well as with the selected boundary conditions. Practical implications: The obtained results can be useful in the designing process (modification of requirements regarding design and construction, as well as materials used in the production of the device, and reduction of risk as far as possible to the patient). They prove that 3D geometrical analysis works quite well for assistive medical devices design. Originality/value: Stress-strain-displacement characteristics of the medical bed’s elements, obtained from the numerical analysis were presented in the work.
6
Content available remote An introduction to the hybrid simulation – the conception of the simulation system
Foit K.
Journal of Achievements in Materials and Manufacturing Engineering
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2010
|
Vol. 39, nr 2
176-183
EN
Purpose: of this paper: The aim of this paper is to present a simple hybrid simulation system, which is composed of virtual reality software and a mathematically oriented application. From the engineer’s point of view, an important possibility is to link together the mathematical software programs with these for creating presentation graphics or virtual reality, in order to create a simulation system with the large customisability. Design/methodology/approach: The coupling of mathematical and virtual reality system can be done in several different ways, using mechanisms for the Interprocess Communication. Findings: It has been assumed that EonX control will be used in a program conceptually similar to the EON Viewer, but equipped with support of basic interprocess communication interfaces in order to maximize flexibility and possibility of data exchange with different applications. Research limitations/implications: The one of specific requirements is to create an appropriate virtual world in EON Studio with use of external events nodes. Practical implications: The simple application named SockED has been created for testing purposes. The SockED application, which is hosting EonX control, acts as DDE server. As an external application any mathematical program that supports the DDE communication can be used (eg. Microsoft Excel, Matlab). There is also theoretical possibility of use the Programmable Logic Controller in similar manner like in case of SCADA application, but this case was not tested yet. Originality/value: There is no program on the market that allows complicated mathematical computation along with high resolution, 3D presentation graphics. The creation of SockED application allowed combining a mathematical program with the powerful graphics engine from EON Reality.
7
Content available remote A method for setting variables in Super Plastic Forming process
Cappetti N., Garofalo L., Naddeo A., Nastasia M., Pellegrino A.
Journal of Achievements in Materials and Manufacturing Engineering
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2010
|
Vol. 38, nr 2
187-194
EN
Purpose: Superplastic forming (SPF) technology exceeds the limit of standard presswork either of form or of thickness distribution, but the lead time and the energy expenditure are more onerous for industrial use. The aim of this work is to study the role that process parameters play in a superplastic forming manufacturing in order to minimize the processing times and the cost respecting the “total quality” of the finished product. Design/methodology/approach: Identified the basic parameters of SPF process that is the thickness of blank, the strain rate and the processing temperature, were chosen three different values for each of them. For each combination of parameters and using finite element software, a forming simulation of a sample part was made. Important parameters as thickness reduction, stress distribution, time/working pressure curve are calculated and evaluated. Findings: The obtained results were manipulated in order to create some global indicators that was analysed to study the reliance on process quality and production costs. Research limitations/implications: The other and more difficult to define parameters, such as cast and initial sheet shape, friction between cast and sheet, need to be evacuated because they also affect the optimisation process, as well as its affordability, that is the result of careful control of process variables. Practical implications: The highlighted dependencies are whatever useful, during process configuration, to drive production choices for quality improvement and cost reduction of superplastic formed components. Originality/value: The interesting result is that some dependencies are not as strong as expected from literature. As an example, the quality parameters dependence on the strain rate is no linear. So much as to the decrease of strain rate some indices worsen considerably.
8
Content available remote Use of a virtual prototyping in construction of a mining machine’s control system
Świder J., Jasiulek D.
Journal of Achievements in Materials and Manufacturing Engineering
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2009
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Vol. 36, nr 2
160-167
EN
Purpose: Possibilities of state-of-the-art information and automation systems in the process of construction and testing the machine’s control system are the project objectives. The concept of virtual prototyping of a roadheader’s control system consisting in coupling the real PLC controller, made by WAGO, with the virtual machine with its surrounding was presented in the paper. Such a solution enables testing the functions of the control system before its installation on a real object, what can significantly reduce the time of the system implementation. Data concerning .NET simulation application made in the Visual Basic language as well as the method of communication between PLC controller and MODBUS TCP simulation application were given. The work also contains a description of basic functions of the roadheader control system as well as assumptions concerning construction of an adaptive control system – which uses the methods of artificial intelligence for analysis of conditions that are around the machine. Design/methodology/approach: Virtual prototyping of a roadheader’s control system consisting in coupling the real PLC controller, made by WAGO, with the virtual machine and with its surrounding. Findings: Trends in the world mining industry indicate for necessity of development roadheader control systems to improve operations associated with roadways driving. Use of a virtual prototyping method will enable to speed up implementation of the system. Research limitations/implications: Building the adaptive system for roadheader control using artificial intelligence will be the next step of the project. Practical implications: The solution presented in the paper is a part of the project aiming at a development of the system for visualization and control of roadheader. The system will be installed in a roadheader manufactured in Poland. Originality/value: Use of the method for virtual prototyping to develop the control system of a mining machine.
9
Content available remote The influence of the engine load on value and temperature distribution in the piston of the turbocharged Diesel engine
Gustof P., Hornik A.
Journal of Achievements in Materials and Manufacturing Engineering
|
2009
|
Vol. 35, nr 2
146-153
EN
Purpose: The determination of the temperature distribution in the piston in initial phase of the work of the turbocharged Diesel engine. Design/methodology/approach: The results of calculations of the temperature distribution in the piston of the turbocharged Diesel engine in dependence from the engine loads were received by means of the two – zone combustion model and the finite element method. Findings: The computations presented the possibility of use of the mathematical models of the combustion processes and the heat transfer on individual surfaces of the piston used by the variable values of the boundary conditions and temperature of the working medium in initial time of the work engine. Research limitations/implications: The modeling of the heat loads was executed for analysis of the values and temperature distribution in the piston in initial phase of the work of the turbocharged Diesel engine until the moment of achievement quasi stabilized temperature values. Originality/value: The results of numeric calculations of the heat loads of the piston displayed the possibility of the use of the original two-zone combustion model and finite elements method to analysis of values and temporary temperature distribution on individual surfaces of the piston.
10
Content available remote Numerical simulation of fatigue degradation process of polymer materials using diagnostic acoustic characteristics
Wróbel G., Kaczmarczyk J.
Journal of Achievements in Materials and Manufacturing Engineering
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2009
|
Vol. 36, nr 2
168-175
EN
Purpose: The objective of the work was to construct the finite elements model for simulation of acoustic wave propagation process in polymer material in the aspect of diagnostic of fatigue changes. Design/methodology/approach: Flat model was composed from finite elements with elastic properties of represented medium. Procedure of model modification corresponding with material fatigue degradation was presented. Acoustic and strength characteristics achieved as a result of numerical analysis gave the basis of numerical diagnostic of degradation process. Findings: Structural modification possibilities of numerical model needed to obtain conformity of experimentally affirmed correlation of strength and acoustic characteristics of material have been indicated. Research limitations/implications: Developed method allows the identification of material’s residual load capacity state on the basis of given, determined in diagnostic process its acoustic characteristics. The method also enables the simulation of variable fatigue process of material in complex constructional conditions. Practical implications: Practical utilization of the model consists in prediction possibility of material state of complex constructional elements in varied operating conditions – on the basis of failure cumulation hypothesis. Originality/value: The value of developed model is in its practical usability in simulation diagnostic process. Simulation method with idea of diagnostic simulation is the original part of the present work.
11
Content available remote FEM-based verification of the PN-EN standard-based stress concentration factor for the drum-pipe joint of a boiler
Dwornicka R.
Journal of Achievements in Materials and Manufacturing Engineering
|
2009
|
Vol. 37, nr 1
48-51
EN
Purpose: The aim of this paper is to present the results of the comparative test between the PN-EN 12952-3:204/Ap1:2005 standard and FEM analysis as procedural tools for determining the stress concentration factor for the drum-pipe joint of a steam boiler. Design/methodology/approach: Geometrical properties of the drum and the pipe are defined. In the first step the stress concentration factor is calculated using the formulas presented in the PN-EN 12952-3:204/Ap1:2005 standard. Then two grid models are defined for unweakened (the drum alone) and weakened (the drum with the pipe) elements. Next, the maximum stresses are computed by FEM analysis conducted in the ANSYS system. A quotient of the maximum stresses gives the FEM-based stress concentration factor. A whole family of factors is created with a stable quotient between element wall thicknesses. Comparative plots of the families are created for both cases: standard-based and FEM-based approaches. Findings: There is rather a good conformity between plots derived from the PN-EN standard and from FEM analysis, with some slight differences due to the approximating character of the semi-empirical formulas presented in the PN-EN standard. Research limitations/implications: The plot presented for the PN-EN standard has limited precision for the geometry of the individual element. The standard presents as an alternative some semi-empirical formulas which are described as ‘approximating’. Ultimately, the numerical methods are more precise tools for determining the stress concentration factor. Practical implications: The results obtained allow the maximum stresses in the cycle to be determined precisely, due to the dependency of the final value on the preceding values in the computation procedure of the stress concentration factor. Originality/value: The calculated formulas may be significantly useful for determining the allowable cooling/heating rates of power plant devices.
12
Content available remote FEM analysis of compression screws used for small bone treatment
Kajzer W., Kajzer A., Marciniak J.
Journal of Achievements in Materials and Manufacturing Engineering
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2009
|
Vol. 33, nr 2
189-196
EN
Purpose: The paper presents results of numerical analysis in metatarsal bone „I” - compression screws system. The aim of the work was determined stresses, strain and displacement in the inserted screws. Design/methodology/approach: Metatarsal bone „I” was selected to researches. The analysis was carried out on the metatarsal bone „I” - compression screws system. The influence of the loads and displacements on the bone - screws system on the results of numerical analyses was analyzed. In order to carry out calculations, 2 models of diverse mechanical properties of screw - Ti-6Al-4V alloy - model 1, stainless steel (Cr-Ni-Mo) - model 2 and two load steps were selected. Findings: The analyses showed the difference in displacements, strains and stresses depending on the selected mechanical properties screws and the way of loads. Research limitations/implications: The limitations were connected with simplification of numerical model of femur as well as with the selected boundary conditions. Two difference way of loads metatarsal bone „I” - compression screws system: 1_force F = 500 N, 2_ displacement l = 1 mm were applied. Practical implications: The obtained results can be useful in clinical practice. They can be applied in selection of stabilization methods or rehabilitation as well as in describing the biomechanical conditions connected with type of bone fracture obtained from medical imaging. Originality/value: Stress-strain-displacement characteristics of metatarsal bone „I” - compression screws system, obtained from the numerical analysis were presented in the work.
13
Content available remote Dynamical flexibility of the free-free damped rod in transportation
Żółkiewski S.
Journal of Achievements in Materials and Manufacturing Engineering
|
2009
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Vol. 35, nr 1
71-78
EN
Purpose: of this thesis is derivation of dynamical flexibility of the free-free rod system in transportation. The well-known problem of dynamical analysis of systems in rotational transportation was developed in this work to systems with taking into consideration damping forces. Design/methodology/approach: The dynamical flexibility method was used to analysis of the free-free rod’s vibrations. Mathematical models derived in previous articles were used to derivation of the dynamical flexibility. Considerations were done by the Galerkin’s method. Findings: There were considered systems in rotational motion treated in this thesis as main transportation. Dynamical characteristics in form of dynamical flexibility as function of frequency and mathematical models were presented in this work. Research limitations/implications: Analyzed systems were simple linear homogeneous not supported rods. Working motion was limited to plane rotational motion. Future works would consider complex systems and nonlinearity. Practical implications: of derived dynamical characteristics can easily support designing process and can be put to use in stability analysis and assigning stability zones. Thank to derived mathematical models the numerical applications can be implemented and some calculations can be automated. Originality/value: Analyzing models are rotating flexible free-free rods with taking into consideration the damping forces.
14
Content available remote Computer modelling system of the chemical composition and treatment parameters influence on mechanical properties of structural steels
Dobrzański L. A., Honysz R.
Journal of Achievements in Materials and Manufacturing Engineering
|
2009
|
Vol. 35, nr 2
138-145
EN
Purpose: This paper presents Neuro-Lab. It is an authorship programme, which use algorithms of artificial intelligence for structural steels mechanical properties estimation. Design/methodology/approach: On the basis of chemical composition, parameters of heat and mechanical treatment and elements of geometrical shape and size this programme has the ability to calculate the mechanical properties of examined steel and introduce them as raw numeric data or in graphic as influence charts. Possible is also to examine the dependence among the selected steel property and chosen input parameters, which describes this property. Findings: There is no necessity of carrying out any additional material tests. The results correlations between calculated and measured values are very good and achieve even the level of 98%. Practical implications: Presented programme can be an effective replace of the real experimental methods of properties determination in laboratory examinations. It can be applied as the enlargement of experimental work. Possible is also the investigation of models coming from new steel species, that wasn’t produced yet. Originality/value: The ability of the mechanical properties estimation of the ready, or foreseen to the use, material is unusually valuable for manufacturers and constructors. This signifies the fulfilment of customer’s quality requirements as well as measurable financial advantages for material manufacturers.
15
Content available remote Application of the neural network for Mg-Al-Zn mechanical properties modelling
Dobrzański L. A., Król M.
Journal of Achievements in Materials and Manufacturing Engineering
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2009
|
Vol. 37, nr 2
549-555
EN
Purpose: The paper presents results of the research connected with the development of new approach based on the neural network to predict chemical composition and cooling rate for the mechanical properties of the Mg-Al-Zn cast alloys. The independent variables on the model are chemical composition of Mg-Al-Zn cast alloys and cooling rate. The dependent parameters are hardness, ultimate compressive strength and grain size. Design/methodology/approach: The experimental magnesium alloy used for training of neural network was prepared in cooperation with the Faculty of Metallurgy and Materials Engineering of the Technical University of Ostrava and the CKD Motory plant, Hradec Kralove in the Czech Republic. The alloy was cooled with three different cooling rates in UMSA Technology Platform. Compression test were conducted at room temperature using a Zwick universal testing machine. Compression specimens were tested corresponding to each of three cooling rates. Rockwell F-scale hardness tests were carried out using a Zwick HR hardness testing machine. Findings: The results of this investigation show that there is a good correlation between experimental and predicted dates and the neural network has a great potential in mechanical behaviour modelling of Mg-Al-Zn alloys. Practical implications: The presented model can be applied in computer system of Mg-Al-Zn casting alloys, selection and designing for Mg-Al-Zn casting parts. Originality/value: The presented model can be applied in computer system of Mg-Al-Zn casting alloys, selection and designing for Mg-Al-Zn casting parts.
16
Content available remote Analytical calculation of the CNC machines servo drives position loop gain
Pandilov Z., Dukovski V.
Journal of Achievements in Materials and Manufacturing Engineering
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2009
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Vol. 37, nr 2
578-583
EN
Purpose: One of the most important factors which influence on the dynamical behavior of the servo drives with rotary and linear motors for CNC machine tools is position loop gain or Kv factor. Design/methodology/approach: From the magnitude of the Kv-factor depends tracking or following error. In multi-axis contouring the following errors along the different axes may cause form deviations of the machined contours. Generally position loop gain Kv should be high for faster system response and higher accuracy, but the maximum gains allowable are limited due to undesirable oscillatory responses at high gains and low damping factor. Usually Kv factor is experimentally tuned on the already assembled machine tool. Findings: This paper presents a simple method for analytically calculation of the position loop gain Kv. A combined digital-analog models of the 6-th order (for rotary motors) and 4-th order (for linear motors) of the position loop are presented. In order to ease the calculation, the 6-th order system or 4-th order system is simplified with a second order model. With this approach it is very easy to calculate the Kv factor for necessary position loop damping. The difference of the replacement of the 6-th order system and 4-th order system with second order system is presented with the simulation program MATLAB. Analytically calculated Kv factor for the servo drives with rotary motors is function of the nominal angular frequency ů and damping D of the servo drive electrical parts (rotary motor and regulator), nominal angular frequency ům and damping Dm of the mechanical transmission elements, as well as sampling period T. Kv factor for the servo drives with linear motors is calculated as function of the nominal angular frequency ům and damping D of the linear motor servo drive electrical parts (motor and regulator) and sampling period T. Research limitations/implications: The influence of nonlinearities was taken with the correction factor Originality/value: Our investigations have proven that experimentally tuned Kv factor differs from analytically calculated Kv factor less than 10%, which is completely acceptable.
17
Content available remote Analysis of complex damped longitudinally vibrating systems in transportation
Żółkiewski S.
Journal of Achievements in Materials and Manufacturing Engineering
|
2009
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Vol. 36, nr 2
176-183
EN
Purpose: of this thesis is dynamical analysis of complex systems in transportation. Analyzed systems are composed of rotatable rods. Transportation was defined as main motion of rods and the overall system. Design/methodology/approach: The dynamical flexibility method is a leading methodology for dynamic analysis of considered systems. For solving equations of motion to dynamical flexibility the Galerkins method was used. Findings: There were considered systems consisted of rods. Rods are rotated first round the origin of global reference frame simultaneously, the attached point and further ones round the end of the previous one. Charts of dynamic characteristics, in a form of dynamic flexibility as function of frequency and mathematical models were shown in this article. Research limitations/implications: All multi-body systems components were simple linear homogeneous rods, the first one as the fixed rod and next ones treated as free-free rods. Transportation was limited to plane rotational motion round the Z axis of global reference frame. Future works would consider complex systems with geometrical and physical nonlinearity. Practical implications: of presented analysis are derivation of multi-body rod systems of dynamic flexibility. Dynamic flexibility can be used in designing process. Presented mathematical models may be used for implementation in numerical applications and for automating some calculations in this type of systems. Originality/value: In the mathematical model the damping forces were taken into consideration and the dynamic flexibility of complex systems was derived.
18
Content available remote Generalization of temporary temperature field correction method in numerical modelling of solidification
Mochnacki B., Szopa R.
Archives of Foundry Engineering
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2008
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Vol. 8, iss. 1 spec.
219--222
EN
The temporary temperature field correction method constitutes a very effective tool for numerical modelling of solidification. The most general version of this algorithm has been presented by Mochnacki [1] and Szopa [2], The basic idea of the method consists in the computations of temperature field for homogeneous domain (e.g. corresponding to molten metal or solid body) and obtained in this way a discrete temperature field for time t is in adequate way 'rebuilt' using the simple mathematical formulae. In this way the non-homogeneous geometry of solidifying casting is taken into account. This approach can be used in the case of macro modelling, in particular when the one domain approach [3, 4, 5, 6] is applied. The basic assumption of the algorithm presented in [ 1 ] and [2] was that the substitute thermal capacity (STC) [7, 8] of casting material can be approximated by a piece-wise constant function. In this paper the generalization of the method on a case of practically optional function describing a course of STC. In the final part of the paper one can find the example of numerical simulations using this approach.
PL
Metoda poprawiania chwilowego pola temperatury jest bardzo efektywnym narzędziem możliwym do wykorzystania przy modelowaniu procesu krzepnięcia. Przedstawioną w pracach Mochnackiego [1] i Szopy [2] wersję dotyczącą schodkowych zmian zastępczej pojemności cieplnej uogólniono na przypadek funkcji o dowolnym przebiegu.
19
Content available remote Explicit and implicit approach of sensitivity analysis in numerical modelling of solidification
Majchrzak E., Kałuża G.
Archives of Foundry Engineering
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2008
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Vol. 8, iss. 1 spec.
187--192
EN
The explicit and implicit approaches of sensitivity analysis using the boundary element method are presented. In particular, the problem of casting solidification is considered. A perturbation of an input parameter (for example the thermal conductivity of casting material) causes the changes of transient temperature field in the domain analyzed. The methods of sensitivity analysis allows to determine in mathematical way the mutual connections between parameters perturbations and final results. In the paper some significant aspects of computational algorithms associated with explicit and implicit approaches of sensitivity analysis are demonstrated.
PL
W artykule przedstawiono jawne i niejawne podejście analizy wrażliwości z zastosowaniem metody elementów brzegowych. W szczególności rozpatrywano proces krzepnięcia. Zaburzenie parametru wejściowego (np. współczynnika przewodzenia ciepła) powoduje zmiany pola temperatury w rozważanym obszarze. Metody analizy wrażliwości pozwalają w matematyczny sposób przedstawić wzajemne zależności między zaburzeniami parametrów a końcowymi wynikami. W pracy pokazano najważniejsze aspekty algorytmów obliczeniowych związanych z jawną i niejawną metodą analizy wrażliwości.
20
Content available remote Estimation of boundary heat flux between casting and mould using the global function specification method
Majchrzak E., Mochnacki B., Suchy J. S.
Archives of Foundry Engineering
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2008
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Vol. 8, iss. 1 spec.
193--198
EN
In the paper the global function specification method is used for identification of time dependent boundary heat flux between casting and mould. The additional information necessary to solve an inverse problem results from the knowledge of heating curves at the points selected from mould sub-domain. The mathematical model of thermal processes proceeding in the casting domain bases on the one domain approach. As the example, the ID system created by casting made from NiCr28W alloy and ceramic mould is considered. On the stage of numerical solution of direct problem and additional one the finite difference method has been applied.
PL
W pracy wykorzystano globalną metodę specyfikacji funkcji do identyfikacji zależnego od czasu strumienia ciepła wymienianego między odlewem a formą odlewniczą. Dodatkowa informacja niezbędna do rozwiązania sformułowanego zadania odwrotnego wynika ze znajomości krzywych nagrzewania w wybranych punktach z obszaru formy. Model matematyczny procesów cieplnych zachodzących w obszarze odlewu bazuje na podejściu odpowiadającym metodzie jednego obszaru. Przykładem ilustrującym rozważania teoretyczne jest rozwiązanie zadania dotyczącego procesów cieplnych w odlewie wykonanym ze stopu NiCr28W wytwarzanego w ceramicznej formie odlewniczej (zadanie ID). Na etapie realizacji numerycznej wykorzystano jawny schemat metody różnic skończonych dla nieliniowych.
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