Wyniki wyszukiwania - Biblioteka Nauki

1

Criteria of material selection for ballistic shields in the context of chosen degenerated models

100%

Kulisiewicz M. , Bocian M. , Jamroziak K.

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2008

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tom Vol. 31, nr 2

505-509

EN

Purpose: The models come from complex rheological models that static and quasi-static loading analysis was presented in the following publications. The main conception of the research is determination of the mechanical properties of ballistic shield materials with the use of the complex constitutive compounds. Design/methodology/approach: In the paper criteria of material selection for ballistic shields in the context of chosen degenerated models are described. Findings: Based on the research in direction of the first phase analysis of the punching process the final result gives designing criteria for the new effective ballistic shields. The results of the presenting analysis give specific technical solution in the context of material selection for the ballistic shields. Practical implications: The article exemplifies the importance of material selection that is responsible for the first punching phase. That data is necessary to design the optimal ballistic shields. Originality/value: The new conception based on degenerated model finds application in analysis of punching process. Nevertheless application of the technical solution will be possible after the new material testing methods are curried out (identification methodology in the dynamic conditions). This is the main goal in the next step of the research.

2

Finite element simulation of wheel impact test

86%

Chang C. L. , Yang S. H.

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2008

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tom Vol. 28, nr 2

167-170

EN

Purpose: In order to achieve better performance and quality, the wheel design and manufacturing use a number of wheel tests (rotating bending test, radial fatigue test, and impact test) to insure that the wheel meets the safety requirements. The test is very time consuming and expensive. Computer simulation of these tests can significantly reduce the time and cost required to perform a wheel design. In this study, nonlinear dynamic finite element is used to simulate the SAE wheel impact test. Design/methodology/approach: The test fixture used for the impact test consists of a striker with specified weight. The test is intended to simulate actual vehicle impact conditions. The tire-wheel assembly is mounted at 13° angle to the vertical plane with the edge of the weight in line with outer radius of the rim. The striker is dropped from a specified height above the highest point of the tire-wheel assembly and contacts the outboard flange of the wheel. Because of the irregular geometry of the wheel, the finite element model of an aluminium wheel is constructed by tetrahedral element. A mesh convergence study is carried out to ensure the convergence of the mesh model. The striker is assumed to be rigid elements. Initially, the striker contacts the highest area of the wheel, and the initial velocity of the striker is calculated from the impact height. The simulated strains at two locations on the disc are verified by experimental measurements by strain gages. The damage parameter of a wheel during the impact test is a strain energy density from the calculated result. Findings: The prediction of a wheel failure at impact is based on the condition that fracture will occur if the maximum strain energy density of the wheel during the impact test exceeds the total plastic work of the wheel material from tensile test. The simulated results in this work show that the total plastic work can be effectively employed as a fracture criterion to predict a wheel fracture of forged aluminum wheel during impact test. Research limitations/implications: A standard impact load is used to carry out the test. For future study, a heavier striker or higher impact can be used to perform the test in order to produce the rupture at impact. Originality/value: In this study, the nonlinear dynamic finite element analysis is performed to simulate a forged aluminium wheel during SAE impact test. The structural damage parameter of the wheel is estimated by the strain energy density, and the fracture criterion is based on the total plastic work of the wheel material. Computer simulation of wheel impact test can significantly reduce the time and cost required to finalize a wheel design.

3

Modelling of dynamical systems in transportation using the modyfit application

72%

Żółkiewski S.

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2008

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tom Vol. 28, nr 1

71-74

EN

Purpose: of this paper is to present a numerical application for analysis and modelling dynamical flexible systems in transportation. This application enables controlling and regulation of rotating systems with the interaction between the working motion and local vibrations of elements. Design/methodology/approach: Numerical calculations are based onto mathematical models derived in other publications. The objectives of making this application were connected with emerging wants of analyzing and modelling rotating systems with taking into consideration relation between main and local motions. Theoretical considerations were made by classical methods and by the Galerkin's method. Findings: In way of increasing the value of angular velocity we can observe creating additional poles in the characteristic of dynamical flexibility and after increasing it is evident that created modes are symmetrically propagated from the original mode. It is evident, instead of modes there are created zeros. Research limitations/implications: Analyzed systems were limited to simple linear type beams and rods. Main motion is plane motion. Future research should consider complex systems and nonlinearity. Practical implications: of the application are possibilities of numerical analysis of beam and rod systems both the free-free ones and fixed ones. Engineers thank to this application can derived the stability zones of analyzed systems and can observe eigenfrequencies and zeros in the way of changing the value of angular velocity. In practice we should implement more adequate models such as those presented in this paper. Originality/value: This paper consist the description of the application called the Modyfit. The Modyfit is an implementation of derived models in a numerical environment. Those models are rotating flexible systems with consideration the transportation effect.

4

Analysis and modelling of rotational systems with the Modyfit application

72%

Żółkiewski S.

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2008

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tom Vol. 30, nr 1

59-66

EN

Purpose: of this article is to present an application to analysis and modelling of rotational systems. Independent modules of application enables controlling and regulation of characteristics of systems in transportation. The base problem of analyzing systems in transportation is expressing the interaction between the main motion and local vibrations of subsystems. Design/methodology/approach: Mathematical models derived in previous articles were used to implement the mathematical models in numerical calculations. The objectives of creating the Modyfit application were connected with analyzing and modelling rotating systems with taking into account relations between major and local motions. Considerations were done by the Galerkin's method. Findings: There are many effects of analyzing systems with rotation consideration. Main of them are connected with analyzing systems in function of increasing the value of angular velocity. In such way of analyzing we can observe creating additional poles in the dynamical characteristics and we can also observe that instead of modes there are created zeros. Research limitations/implications: Analyzed systems are simple linear homogeneous beams and rods. Working motion is limited to plane motion. Future research would consider complex systems, damping and nonlinearity. Practical implications: of the application are numerical analysis of beams and rods in rotational transportation and designing such systems. Thank to the Modyfit we can derived the stability zones of analyzed beams and rods and we can observe eigenfrequencies and zeros in function of angular velocity. Originality/value: The Modyfit is a forerunner implementation of derived models in a numerical environment of dynamical flexibility. Analyzing models are rotating flexible systems with consideration the rotational transportation effect.

5

Application of artificial neural networks in modelling of quenched and tempered structural steels mechanical properties

72%

Dobrzański L. A. , Honysz R.

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2010

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tom Vol. 40, nr 1

50-57

EN

Purpose: This paper presents the application of artificial neural networks for mechanical properties prediction of structuralal steels after quenching and tempering processes. Design/methodology/approach: On the basis of input parameters, which are chemical composition, parameters of mechanical and heat treatment and dimensions of elements, steels’ mechanical properties : yield stress, tensile strength stress, elongation, area reduction, impact strength and hardness are predicted. Findings: Results obtained in the given ranges of input parameters indicates on very good ability of artificial neural networks to values prediction of described mechanical properties for steels after quenching and tempering processes. The uniform distribution of descriptive vectors in all, training, validation and testing sets, indicates on good ability of the networks to results generalisation. Practical implications: Artificial neural networks, created during modelling, allows easy prediction of steels properties and allows the better selection of both chemical composition and the processing parameters of investigated materials. It’s possible to obtain steels, which are qualitatively better, cheaper and more optimised under customers needs. Originality/value: The prediction possibility of the material mechanical properties is valuable for manufacturers and constructors. It allows the preservation of customers quality requirements and brings also measurable financial advantages

6

Computer models of steam pipeline components in the evaluation of their local strength

72%

Okrajni J. , Essler W.

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2010

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tom Vol. 39, nr 1

71-78

EN

Purpose: The paper discusses the issue of modelling the heating and cooling processes of T-pipes in a power plant pipeline in the start-up conditions of a boiler. The main purpose of this work is the description of the mechanical behaviour of power plant components working under mechanical and thermal loading and validation of the computer modelling methods. Design/methodology/approach: The FEM modelling has been used to describe the local stress-strain behaviour of the chosen component. Findings: The reasons for the presence of high and variable in time temperature gradients in the components of the main steam pipeline include, among other things, variable values of the coefficient of heat transfer between the pipeline material and the medium flowing inside it, which, at this stage of boiler operation, may change its state. Unsteady operation of a pipeline, especially in case of subsequent boiler start-ups, may induce thermal stresses which exceed the values of allowable stress in components of complex shapes. Research limitations/implications: The possibility of applying the durability criteria currently assumed in standards still requires justification and confirmation in laboratory and industrial conditions to be closer to the real components behaviour. In such situation the presented analysis is the part of the complex investigation method which main purpose is increasing accuracy of the TMF process description and thermo-mechanical life assessment. Practical implications: The calculations carried out may constitute a basis for developing a material test parameters which would bring closer the fatigue conditions appearing locally in the analysed components. The method of stress-strain behaviour analysis used in the paper could be useful in the practical cases when the real components mechanical behaviour would be analysed. Originality/value: The main value of this paper is the own method of the mechanical behaviour analysis of the power plant component. This method includes the temperature fields analysis taking into account the boundary conditions based on the operation parameter data and the thermoplastic material model. The material stress-strain behaviour has been treated as the local phenomenon, that could be modelled by FEM.

7

Biomechanical behaviour of coronary stent design with OCC technology

72%

Walke W. , Paszenda Z. , Jurkiewicz W.

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2007

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tom Vol. 20, nr 1-2

199-202

EN

Purpose: The work presents results of stresses and strains of three-layer vascular stent (Cr-Ni-Mo - Ta - Cr-Ni-Mo) and one-layer uniform one (Cr-Ni-Mo) used in operative cardiology. Design/methodology/approach: On the basis of the geometrical model a finite element mesh was generated. The discretization process was realized with the use of the SOLID95 element. The set boundary conditions represented the phenomena which occur during baloon expanding. Findings: The numerical analysis of the three-layer stent showed diverse distribution of stresses and strains in the individual layers. Minimum stresses in the analyzed range of expansion diameters (d=2.25-3.50 mm) were observed in the middle layer made of tantalum. Maximum stresses were observed in the layer made of the stainless steel. Research limitations/implications: Values of stresses and strains in different stents' regions caused by applied displacements are valuable information for appropriate design of the geometry, hardening of the metallic biomaterial and forming of physio-chemical properties of surface layer. Originality/value: The obtained results are valuable for selection of surface layer which is mainly responsible for ensuring proper hemocompatibility of the stent. The deformable surface layer is an effective way to reduce the surface reactivity of the stent in blood environment and in consequence coagulation.

8

Materials science virtual laboratory as an example of the computer aid in materials engineering

72%

Dobrzański L. A. , Honysz R.

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2007

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tom Vol. 24, nr 2

219-222

EN

Purpose: The purpose of the presented article is to describe the material science virtual laboratory, which is an open scientific, investigative, simulating and didactic medium for the realization of the didactic and educational tasks performed by traditional and e-learning methods. Design/methodology/approach: The laboratory is an aggregate of testers and training simulators, placed in the virtual reality and created in various languages and the programming techniques, which represents the properties, functionality and manual principles of real equipment installed and accessible in the real laboratories of scientific universities. Findings: Application of the equipment, that is practically imperishable, cheap in exploitation and easy in the use certainty will encourage students and scientific workers to independent audits and experiments in situations, where the possibilities of their execution in the true investigative laboratory will be limited because of the high material costs, difficult access to real equipment or the possible risk of his damage. Practical implications: The use possibilities of the virtual laboratory are practically unrestricted; it can be a base for any studies, course or training programme. It is assumed, that the project of the laboratory as fully multimedial. The participants of this laboratory can e.g. investigate training experiments from the definite field of material engineering, give questions, pass tests, contact with lecturers and the different users of the laboratory and obviously on participate in his design and content. Originality/value: The project of the virtual laboratory corresponds with the global tendency for expand the investigative and academical centers about the possibilities of training and experiments performance with use of the virtual reality. This enriches the education programme of the new abilities reserved so far exclusively for effecting only on real equipment.

9

Modelling of transport phenomena in gas tungsten arc welding

72%

Farzadi A. , Serajzadeh S. , Kokabi A. H.

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2007

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tom Vol. 28, nr 7

417-420

EN

Purpose: Since numerical heat transfer and fluid flow models have provided significant insight into welding process and welded materials that could not been achieved otherwise, there has been an important interest in the quantitative representation of transport phenomena in the weld pool. On the other hand, the temperature and velocity distributions of the molten metal as well as the cooling rate after welding operation affect the weld geometry, the microstructure, and the mechanical properties of weld zone. This work demonstrates that the application of numerical transport phenomena can significantly add to the quantitative knowledge in welding and help the welding community in solving practical problems. Design/methodology/approach: The temperature and velocity fields are simulated using the solution of the equations of conversation of mass, energy and momentum in three-dimension and under steady-state heat transfer and fluid flow conditions. Findings: The weld pool geometry and various solidification parameters were calculated. The calculated weld pool geometries were in good agreement with the ones obtained using the experiments. The solidification parameters of G and G/R are determined. It is found that as the welding speed increases, the value of G/R at the weld pool centerline decreases. Research limitations/implications: Welding process used is this study is gas tungsten arc (GTA) welding and base metal is commercial pure aluminum. This model can be investigated to simulate other materials and welding processes. Also the results of this study such as the temperature field can be used in the simulation of microstructure, mechanical properties, etc of welding zone. Originality/value: In this research the solidification parameters of G, R and G/R can be used for prediction of the solidification morphology and the scale of the solidification structure.

10

Application of artificial neural networks in modelling of normalised structural steels mechanical properties

72%

Dobrzański L. A. , Honysz R.

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2009

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tom Vol. 32, nr 1

37-45

EN

Purpose: This paper presents the application of artificial neural networks for mechanical properties prediction of structural steels after heat treatment. Design/methodology/approach: On the basis of such input parameteres, which are the chemical composition, the kind of mechanical and heat treatment and dimensions of elements, mechanical properties, such as strength, impact resistance or hardness are predicted. Findings: Results obtained in the given ranges of input parameters show very good ability of constructed neural networks to predict described mechanical properties for steels after heat treatment. The uniform distribution of descriptive vectors in all, training, validation and testing sets, indicate about the good ability of the networks to results generalisation. Practical implications: Created tool makes possible the easy modelling of described properties and allows the better selection of both chemical composition and the processing parameters of investigated materials. At the same time the obtainment of steels, which are qualitatively better, cheaper and more optimised under customers needs is made possible. Originality/value: The prediction possibility of the material mechanical properties is valuable for manufacturers and constructors. It allows preserving the customers quality requirements and brings also measurable financial advantages.

11

Analysis of a degenerated standard model in the piercing process

72%

Jamroziak K.

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2007

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tom Vol. 22, nr 1

49-52

EN

Purpose: The purpose of this paper is the mathematical description of the impact phenomenon of a bullet of the speed ca. 400 m/s, with the use of a degenerated model. Design/methodology/approach: In the study, an attempt has been made to apply an untypical model for the piercing phenomenon analysis. Basing on the model, the theoretical analysis of the piercing phenomenon in quasistatic and dynamic load conditions, in the impact load form, has been carried out. Findings: This analysis enabled derivation of significant conclusions useful in the design process of effective ballistic shields. Research limitations/implications: In the study, the concept has been assumed that a dynamic model, simple as possible, that may be analyzed not only by numerical methods but also (at least approximately) with the mathematical analysis methods, may provide significant directions concerning material piercing. Practical implications: The use of so called degenerated model allows to describe the phenomenon in more detail at various piercing speeds what extends the possibilities in the sphere of designing the optimum ballistic shields and of identification of the properties of materials applied for construction of shields. Originality/value: The proposed method of identification of material properties in the piercing process, within the relation: force - deforamtion, is a novel one since the essence of the identification is the standard rheological model in an adequate plastic component describing the viscous attenuation with dry friction.

12

Numerical analysis of beams on unilateral elastic foundation

72%

Torbacki W.

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2008

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tom Vol. 29, nr 2

109-112

EN

Purpose: The main issue of this paper is to present results of finite element analysis of beams elements on unilateral elastic foundation received with a use of special finite elements of zero thickness designated for foundation modelling. Design/methodology/approach: Computer strength analysis with a use of Finite Element Method (FEM) was carried out. Findings: The paper presents possibilities of special finite elements of zero thickness which enable taking into consideration unilateral contact in construction-foundation interaction as well as an impact of surrounding construction environment to its behaviour. Research limitations/implications: Further researches should concentrate on taking into consideration a multi-layer aspects as well as elasto-plasticity of foundation. Practical implications: Modern engineering construction on elastic foundation analyze require not only standard analysis on Winkler (one parameter) foundation but also calculation of construction on two-parameter foundation which will take into consideration a possibility of loosing contact between construction and foundation (unilateral contact). Originality/value: The paper can be useful for person who performs strength analysis of beams on elastic foundation with a use of finite element method.

13

Process description of piercing when using degenerated model

72%

Jamroziak K.

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2008

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tom Vol. 26, nr 1

57-64

EN

Purpose: The material piercing process is an extremely complex phenomenon for the theoretical analysis. This is connected with the fact that the materials used mainly for ballistic shields may not be treated as isotropic media. The description of piercing of ballistic shields made of light weight composite materials, on the basis of the Hooke's model and the Young's module reflects the too low result effectiveness for practical applications. The purpose of this article is the mathematical description of the impact phenomenon of a bullet of the speed ca. 400 m/s, with the use of a degenerated model. Design/methodology/approach: In the study, an attempt has been made to apply an untypical model for the piercing phenomenon analysis. Basing on the model, the theoretical analysis of the piercing phenomenon in quasistatic and dynamic load conditions, in the impact load form, has been carried out. Findings: This analysis enabled derivation of significant conclusions useful in the design process of effective ballistic shields. Research limitations/implications: In the study, the concept has been assumed that a dynamic model simple as possible, that may be analyzed not only by numerical methods but also (at least approximately) with the mathematical analysis methods, may provide significant directions concerning material piercing. Practical implications: The use of so called degenerated model allows to describe the phenomenon in more detail at various piercing speeds what extends the possibilities in the sphere of designing the optimum ballistic shields and of identification of the properties of materials applied for construction of shields. Originality/value: The proposed method of identification of material properties in the piercing process, within the relation: force – deformation, is a novel one since the essence of the identification is the standard rheological model in an adequate plastic component describing the viscous attenuation with dry friction.

14

Thermo-mechanical fatigue conditions of power plant components

72%

Okrajni J.

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2009

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tom Vol. 33, nr 1

53-61

EN

Purpose: The main purpose of this work is the description of the mechanical behaviour of power plant components working under mechanical and thermal loading that cause the thermo-mechanical fatigue fracture in selected areas of the component surfaces. Design/methodology/approach: The computer modelling has been used to describe the local stress-strain behaviour of the chosen component. Findings: The values of variable in time temperature strains and stresses in selected points of the power plant header were determined. The points were located at the edges of holes through which water steam is supplied and carried away, where under use conditions the presence of cracks can be observed. That stresses and mechanical strains caused by the influence of a non-uniform temperature field may be significantly higher in comparison with the stresses and strains caused by the pressure inside the analysed component. Tensile thermal stresses of high values are created especially under conditions of sudden cooling during unsteady work of a power unit. Research limitations/implications: The possibility of applying the durability criteria currently assumed in standards still requires justification and confirmation in laboratory and industrial conditions to be closer to the real components behaviour. In such situation the presented analysis is the part of the complex investigation method which main purpose is increasing accuracy of the TMF process description and thermo-mechanical life assessment. Practical implications: The calculations carried out may constitute a basis for developing a material test parameters which would bring closer the fatigue conditions appearing locally in the analysed components. The method of stress-strain behaviour analysis used in the paper could be useful in the practical cases when the real components mechanical behaviour would be analysed. Originality/value: The main value of this paper is the own method of the mechanical behaviour analysis of the power plant component. This method includes the temperature fields analysis taking into account the boundary conditions based on the operation parameter data and the thermoplastic material model. The material stress-strain behaviour has been treated as the local phenomenon, that could be modelled by FEM.

15

Dynamical flexibility of the free-free damped rod in transportation

72%

Żółkiewski S.

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2009

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tom 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.

16

Analysis of complex damped longitudinally vibrating systems in transportation

72%

Żółkiewski S.

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2009

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tom 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.

17

Computer modelling system of the chemical composition and treatment parameters influence on mechanical properties of structural steels

72%

Dobrzański L. A. , Honysz R.

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2009

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tom 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.

18

Research activities of computer-aided materials processing laboratory

72%

Im Y. T. , Lee H. W. , Lee H. C. , Awais M. , Jin Y. G. , Jung K. H. , Jung K. H.

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2007

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tom Vol. 24, nr 1

219-229

EN

Purpose: of this paper is to review the research works carried out at the national research laboratory for computer-aided materials processing at the department of mechanical engineering at KAIST. Design/methodology/approach: The research papers published so far from the laboratory were carefully reviewed and highlights for developing simulation tools for mesh generation, 2D or 3D finite element analyses for forging, shape rolling, solidification, semi-solid forging, compression molding of thermoset composites, injection molding without or with short fibers, and expert system for multi-stage axi-symmetric cold forging, extrusion, and multi-pass shape rolling are recaptured. Findings: According to this survey, the important issues involved with program developments and their industrial applications were revisited. Research limitations/implications: Understanding of material behaviour at various processing conditions and characterization of proper boundary conditions in terms of friction and temperature should be carefully made. Handling of complex geometry and computational efficiency for such geometry should be improved as well. Further development of three dimensional design systems should be necessary. Practical implications: Proper usage of the simulation tools and interface such tools with the automatic design system with the help of artificial intelligence will be very useful at the design stage of new manufacturing products and processes. In addition, proper understanding of deformation mechanics is of importance to properly utilize such numerical tools. Originality/value: Various aspects of limitations involved with program developments and their usage are identified and some important industrial applications demonstrated.

19

Biomechanical characterization of the balloon-expandable slotted tube stents

72%

Pochrząst M. , Walke W. , Kaczmarek M.

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2009

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tom Vol. 37, nr 2

340-347

EN

Purpose: The aim of the presented work was determination of the biomechanical characteristics of the vascular stent made of stainless steel (Cr-Ni-Mo) and Co-Cr-W-Ni alloy. Additionally, in order to compare obtained results, an experimental analysis of the stent made of stainless steel was carried out. Design/methodology/approach: In order to determine the strength characteristics of the analyzed stent the finite element method was applied. Geometrical model of the vascular stent, which was meshed with the use of the SOLID95 element, was worked out. Selection of the finite element was conditioned by large strains that occur during angioplastic procedure. The established boundary conditions imitated the phenomena during the balloon expansion in real conditions. Findings: The result of the analysis was determination of relationship between equivalent stresses and strains in the individual regions the stent in the function of the diameter’s change (d = 1.20 - 4.00 mm) caused by expanding pressure. Analysis of the obtained results indicates diverse distribution of stresses and strains in the stent depending on the applied biomaterial. Research limitations/implications: The obtained results of the biomechanical analysis of the coronary stent are valuable information for correct design of the geometry and mechanical properties of the applied metallic biomaterials. Strain analysis of the stent indicates that in order to limit a surface reactivity of the stent in blood environment, a deformable surface layer must be applied. Originality/value: Results of the numerical analysis indicate that mechanical properties of the metallic biomaterials used to manufacture the analyzed vascular stent were selected correctly. The correctness of the selection (mechanical properties of the metallic biomaterials) should be confirmed in in vitro tests realized with the use of the coronary angioplasty set.

20

Identification of composite materials at high speed deformation with the use of degenerated model

72%

Jamroziak K. , Bocian M.

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2008

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tom Vol. 28, nr 2

171-174

EN

Purpose: Composite materials on account of some their characteristics have application in a construction of ballistic shield. An example of the ballistic shield is laminate with the mix-structure materials such as layer pressed of aramid cloths on matrix polymer. Because of the shield’s assignment the aramid cloths are exposed to impact loads caused by an energy made by impact force of cumulated mass (bullet). Previous analyses of the effect are based on linear-elastic reaction of resisting forces between the materials of a bullet and a shield. The article exemplifies the procedure of mechanical properties analysis in the punch effect of the ballistic shield with the use of some of the non-elastic models. Design/methodology/approach: In the article the theoretical analysis of punch effect in the quasi-static load condition based on some of the degenerated models is also presented. Findings: The results of the analysis make aware of demand for designing safety ballistic shields. Research limitations/implications: The main conception was optimum material selection (composite) that has to be done according to the theoretical analysis, which is based on non-elastic models selected in the context of velocity and mass of punching bullet. Practical implications: Application of the complex degenerated model allows to define more characteristics of the punching process of the ballistic shield. Determination of the effect of energy impact dissipation causes material damage of the ballistic shield is enabled to do because of implementation of boundary conditions. Originality/value: Based on the boundary conditions of energy in the way of changing parameters of model we are able to describe non-destructive deformation process.