Miran Ulbin | University of Maribor (original) (raw)

Papers by Miran Ulbin

Research paper thumbnail of Knowledge-Based System for Supporting the Design of a Plate-Press

Journal of Computing and Information Science in Engineering, 2012

ABSTRACT This paper presents a knowledge-based system capable of giving the designer quality supp... more ABSTRACT This paper presents a knowledge-based system capable of giving the designer quality support when making decisions from the aspect of modeling the reinforcement of a plate-press within a position of maximum compressive load, and by choosing suitable material for the plate. Based on the selected combination of reinforcement and material, this system acquaints the user with the size and position of the largest comparative stress, and the greatest nodal displacement in the load-direction. This system operates based on the implemented knowledge of experts in the execution of design, material selection, and numerical analysis based on the finite-element method (FEM), which was written with the help of parameters within the knowledge-base of the CATIA V5 CAD-system. Using this system gives the user an opportunity to reach conclusions that are crucial for designing a plate-press or pressure-loaded die-elements, in general. The results reveal that the system can dramatically shorten design time and improve design quality in comparison to manual design process. [DOI: 10.1115/1.4006444]

Research paper thumbnail of STUDIES IN NUMERICAL STABILITY OF EXPLICIT CONTACT-IMPACT ALGORITHM TO THE FINITE ELEMENT SOLUTION OF WAVE PROPAGATION PROBLEMS

Research paper thumbnail of Fatigue Crack Initiation Along Inclusion Interfaces of Contacting Mechanical Elements

Fracture of Nano and Engineering Materials and Structures, 2006

ABSTRACT

Research paper thumbnail of Object Oriented Programming of Engineering Numerical Applications

Advances in Computational Structures Technology, 1996

Research paper thumbnail of Computational assessment of the allowable static contact loading of a roller-slewing bearing׳s case-hardened raceway

International Journal of Mechanical Sciences, 2015

Research paper thumbnail of Simulating the impact of a truck on a road-safety barrier

Research paper thumbnail of Assessment of methods for computing the closest point projection, penetration, and gap functions in contact searching problems

International Journal for Numerical Methods in Engineering, 2015

ABSTRACT

Research paper thumbnail of UTILISING OPTIMIZATION METHODS FOR COMPUTING OF NORMAL VECTOR TO CONTACT SURFACE

The stability of the contact algorithm using the penalty method is significantly affected by choo... more The stability of the contact algorithm using the penalty method is significantly affected by choosing of the penalty function. The penalty function is usually defined like a magnitude of the penetration vector multiplied by the users-defined constant-the penalty parameter. The penetration vector is obtained by solution of the minimum distance problem between the node/Gaussian integration point and the segment of the element. For a general quadrilateral contact segment this task leads to the system of two nonlinear equations. It is shown that the popular Newton-Raphson method is inadvisable for this problem. In this paper, alternative methods like quasi-Newton methods, gradient methods and the simplex method are presented. Especial attention is put on the line-search method that is crucial for a general success of quasi-Newton methods as well as gradient methods. All mentioned methods are tested by means of numerical example, which involves bending of two rectangular plates over a cy...

Research paper thumbnail of FINITE ELEMENT CONTACT-IMPACT ALGORITHM IN EXPLICIT TRANSIENT ANALYSIS

This work addresses three issues in computational modelling of contact-impact problems: i) overvi... more This work addresses three issues in computational modelling of contact-impact problems: i) overviews a contact algorithm proposed by these authors, ii) local search treatment based on the mod-ification of the Nelder-Mead simplex method, iii) discusses an algorithmic aspects of contact algorithm in conjunction with the explicit time integration scheme. The talk closes with the presentation of several numerical examples including the longitudinal impact of two thick plates, for which analytical solution is available.

Research paper thumbnail of GAJA: 3D CAD methodology for developing a parametric system for the automatic (re)modeling of the cutting components of compound washer dies

Journal of Zhejiang University SCIENCE A, 2013

Research paper thumbnail of An automated design system for compound washer dies

Journal of the Brazilian Society of Mechanical Sciences and Engineering, 2013

ABSTRACT The designing of stamping dies is a complex process influenced by numerous design parame... more ABSTRACT The designing of stamping dies is a complex process influenced by numerous design parameters, which can be classified into independent and dependent parameters. Before starting the design process a designer must identify, analyze, and calculate these parameters needing a wide range of knowledge. The design task is then accomplished on the basis of these parameter values that must be incorporated into the die design’s elements, in order to achieve workable and quality designs. Since most of the 3D CADs provide insufficient help in this regard, an automated system has been developed in CATIA V5 for the automatic designing of compound dies intended for production of various washer configurations. This system operates on the basis of an integrated design knowledge embedded inside washer, strip, and die-parts’ generative models using user parameters and a programmatically established relations between them. The use of this system significantly shortens the design time, and denotes design quality.

Research paper thumbnail of Crash Simulations of Road Safety Barriers Using LS-DYNA on MPP Computing Platforms

Proceedings of the Fifth International Conference on Engineering Computational Technology, 2006

Research paper thumbnail of Surface initiated crack growth simulation in moving lubricated contact

Theoretical and Applied Fracture Mechanics, 2002

The paper describes a two-dimensional computational model for simulating surface initiated crack ... more The paper describes a two-dimensional computational model for simulating surface initiated crack growth in the lubricated contact area that leads to surface pitting of mechanical components. The model assumes size and orientation of the initial crack which is subjected to contact loading conditions, accounting for the elasto-hydrodynamic-lubrication effects and tangential loading due to sliding. The influence of a lubricating fluid, driven into the crack by hydraulic mechanism, is also considered. The minimum strain energy density criterion is used to analyze crack propagation with the aim of the finite element analysis. The model is applied to a real pitting problem of a gear. The results for pit sizes correlate well with those observed in experimental testing.

Research paper thumbnail of Contact problems of gears using Overhauser splines

International Journal of Mechanical Sciences, 1999

This paper presents a new finite element technique which provides more accurate contact stress pr... more This paper presents a new finite element technique which provides more accurate contact stress predictions than other already established methods. A novel contact detection algorithm in the framework of the contact problem analysis with the finite element method using Overhauser splines is presented. Using this approach the contact area is approximated with Overhauser spline interpolation functions over boundary nodes, which results in 'smooth' and accurate geometrical descriptions that is crucial to contact stress analysis. The geometry is also completely decoupled from the finite element polynomial shape functions. A single parametric curve is used to model the contacting surface providing the C boundary continuity and exact boundary condition definition. In addition, the geometrical description using splines provides the data required for actual contact area determination and exact contact size calculation. Implementation of the proposed approach in the developed finite element code is presented. Benefits and drawbacks of the proposed approach are discussed. The method is successfully used for simulation of contact problems in gears.

Research paper thumbnail of A fracture mechanics model for the analysis of micro-pitting in regard to lubricated rolling–sliding contact problems

International Journal of Fatigue, 2007

... The tangential stress, which includes the influence of stress intensity factors K I , K II , ... more ... The tangential stress, which includes the influence of stress intensity factors K I , K II , T-stress and constant internal pressure to the crack's surfaces, can be written in polar co-ordinates as [10]: (8) View the MathML source where the tractions View the MathML source and View ...

Research paper thumbnail of Symmetry preserving algorithm for large displacement frictionless contact by the pre-discretization penalty method

International Journal for Numerical Methods in Engineering, 2004

Abstract A three-dimensional contact algorithm based on the pre-discretization penalty method is ... more Abstract A three-dimensional contact algorithm based on the pre-discretization penalty method is presented. Using the pre-discretization formulation gives rise to contact searching performed at the surface Gaussian integration points. It is shown that the proposed ...

Research paper thumbnail of Simulation of crash tests for high containment levels of road safety barriers

Engineering Failure Analysis, 2007

This paper presents the results of computer simulations of road safety barrier behaviour under ve... more This paper presents the results of computer simulations of road safety barrier behaviour under vehicle crash conditions for high containment levels as mandated by the European standard EN 1317. Simulations were performed with the explicit finite element code LS-...

Research paper thumbnail of Post-processing techniques for assessing element distortion errors

Engineering Computations, 1989

Abstract: Finite element meshes can today be used to represent very complex structures because of... more Abstract: Finite element meshes can today be used to represent very complex structures because of high performance hardware and software. Although a very successful contributor to modern engineering analysis, such techniques are prone to certain classes of ...

Research paper thumbnail of Internal structure characterization of AlSi7 and AlSi10 advanced pore morphology (APM) foam elements

Materials Letters, 2014

ABSTRACT The paper presents a detailed geometrical characterization of APM foam elements with sph... more ABSTRACT The paper presents a detailed geometrical characterization of APM foam elements with sphere-like interconnected closed-cell porous structure and integral skin. The influence of the alloying element Si on internal structure (pore size, spatial distribution, sphericity and orientation) for different APM foam element sizes (made of AlSi7 and AlSi10) has been evaluated and quantified using an improved and novel approach based on micro-computed tomography data acquisition.

Research paper thumbnail of Intelligent system for the automatic calculation of stamping parameters

SCOPE & TOPICS Advances in Production Engineering & Management (APEM) is an interdisciplinary ref... more SCOPE & TOPICS Advances in Production Engineering & Management (APEM) is an interdisciplinary refereed academic journal. The main goal of the APEM is to present high quality research developments in all areas of production engineering and production management, as well as their applications in industry and services, to a broad audience of academics and practitioners. In order to bridge the gap between theory and practice, applications and case studies are particularly welcome. For theoretical papers, their originality and research contributions are the main factors in the evaluation process. Fields of interest include, but are not limited to:

Research paper thumbnail of Knowledge-Based System for Supporting the Design of a Plate-Press

Journal of Computing and Information Science in Engineering, 2012

ABSTRACT This paper presents a knowledge-based system capable of giving the designer quality supp... more ABSTRACT This paper presents a knowledge-based system capable of giving the designer quality support when making decisions from the aspect of modeling the reinforcement of a plate-press within a position of maximum compressive load, and by choosing suitable material for the plate. Based on the selected combination of reinforcement and material, this system acquaints the user with the size and position of the largest comparative stress, and the greatest nodal displacement in the load-direction. This system operates based on the implemented knowledge of experts in the execution of design, material selection, and numerical analysis based on the finite-element method (FEM), which was written with the help of parameters within the knowledge-base of the CATIA V5 CAD-system. Using this system gives the user an opportunity to reach conclusions that are crucial for designing a plate-press or pressure-loaded die-elements, in general. The results reveal that the system can dramatically shorten design time and improve design quality in comparison to manual design process. [DOI: 10.1115/1.4006444]

Research paper thumbnail of STUDIES IN NUMERICAL STABILITY OF EXPLICIT CONTACT-IMPACT ALGORITHM TO THE FINITE ELEMENT SOLUTION OF WAVE PROPAGATION PROBLEMS

Research paper thumbnail of Fatigue Crack Initiation Along Inclusion Interfaces of Contacting Mechanical Elements

Fracture of Nano and Engineering Materials and Structures, 2006

ABSTRACT

Research paper thumbnail of Object Oriented Programming of Engineering Numerical Applications

Advances in Computational Structures Technology, 1996

Research paper thumbnail of Computational assessment of the allowable static contact loading of a roller-slewing bearing׳s case-hardened raceway

International Journal of Mechanical Sciences, 2015

Research paper thumbnail of Simulating the impact of a truck on a road-safety barrier

Research paper thumbnail of Assessment of methods for computing the closest point projection, penetration, and gap functions in contact searching problems

International Journal for Numerical Methods in Engineering, 2015

ABSTRACT

Research paper thumbnail of UTILISING OPTIMIZATION METHODS FOR COMPUTING OF NORMAL VECTOR TO CONTACT SURFACE

The stability of the contact algorithm using the penalty method is significantly affected by choo... more The stability of the contact algorithm using the penalty method is significantly affected by choosing of the penalty function. The penalty function is usually defined like a magnitude of the penetration vector multiplied by the users-defined constant-the penalty parameter. The penetration vector is obtained by solution of the minimum distance problem between the node/Gaussian integration point and the segment of the element. For a general quadrilateral contact segment this task leads to the system of two nonlinear equations. It is shown that the popular Newton-Raphson method is inadvisable for this problem. In this paper, alternative methods like quasi-Newton methods, gradient methods and the simplex method are presented. Especial attention is put on the line-search method that is crucial for a general success of quasi-Newton methods as well as gradient methods. All mentioned methods are tested by means of numerical example, which involves bending of two rectangular plates over a cy...

Research paper thumbnail of FINITE ELEMENT CONTACT-IMPACT ALGORITHM IN EXPLICIT TRANSIENT ANALYSIS

This work addresses three issues in computational modelling of contact-impact problems: i) overvi... more This work addresses three issues in computational modelling of contact-impact problems: i) overviews a contact algorithm proposed by these authors, ii) local search treatment based on the mod-ification of the Nelder-Mead simplex method, iii) discusses an algorithmic aspects of contact algorithm in conjunction with the explicit time integration scheme. The talk closes with the presentation of several numerical examples including the longitudinal impact of two thick plates, for which analytical solution is available.

Research paper thumbnail of GAJA: 3D CAD methodology for developing a parametric system for the automatic (re)modeling of the cutting components of compound washer dies

Journal of Zhejiang University SCIENCE A, 2013

Research paper thumbnail of An automated design system for compound washer dies

Journal of the Brazilian Society of Mechanical Sciences and Engineering, 2013

ABSTRACT The designing of stamping dies is a complex process influenced by numerous design parame... more ABSTRACT The designing of stamping dies is a complex process influenced by numerous design parameters, which can be classified into independent and dependent parameters. Before starting the design process a designer must identify, analyze, and calculate these parameters needing a wide range of knowledge. The design task is then accomplished on the basis of these parameter values that must be incorporated into the die design’s elements, in order to achieve workable and quality designs. Since most of the 3D CADs provide insufficient help in this regard, an automated system has been developed in CATIA V5 for the automatic designing of compound dies intended for production of various washer configurations. This system operates on the basis of an integrated design knowledge embedded inside washer, strip, and die-parts’ generative models using user parameters and a programmatically established relations between them. The use of this system significantly shortens the design time, and denotes design quality.

Research paper thumbnail of Crash Simulations of Road Safety Barriers Using LS-DYNA on MPP Computing Platforms

Proceedings of the Fifth International Conference on Engineering Computational Technology, 2006

Research paper thumbnail of Surface initiated crack growth simulation in moving lubricated contact

Theoretical and Applied Fracture Mechanics, 2002

The paper describes a two-dimensional computational model for simulating surface initiated crack ... more The paper describes a two-dimensional computational model for simulating surface initiated crack growth in the lubricated contact area that leads to surface pitting of mechanical components. The model assumes size and orientation of the initial crack which is subjected to contact loading conditions, accounting for the elasto-hydrodynamic-lubrication effects and tangential loading due to sliding. The influence of a lubricating fluid, driven into the crack by hydraulic mechanism, is also considered. The minimum strain energy density criterion is used to analyze crack propagation with the aim of the finite element analysis. The model is applied to a real pitting problem of a gear. The results for pit sizes correlate well with those observed in experimental testing.

Research paper thumbnail of Contact problems of gears using Overhauser splines

International Journal of Mechanical Sciences, 1999

This paper presents a new finite element technique which provides more accurate contact stress pr... more This paper presents a new finite element technique which provides more accurate contact stress predictions than other already established methods. A novel contact detection algorithm in the framework of the contact problem analysis with the finite element method using Overhauser splines is presented. Using this approach the contact area is approximated with Overhauser spline interpolation functions over boundary nodes, which results in 'smooth' and accurate geometrical descriptions that is crucial to contact stress analysis. The geometry is also completely decoupled from the finite element polynomial shape functions. A single parametric curve is used to model the contacting surface providing the C boundary continuity and exact boundary condition definition. In addition, the geometrical description using splines provides the data required for actual contact area determination and exact contact size calculation. Implementation of the proposed approach in the developed finite element code is presented. Benefits and drawbacks of the proposed approach are discussed. The method is successfully used for simulation of contact problems in gears.

Research paper thumbnail of A fracture mechanics model for the analysis of micro-pitting in regard to lubricated rolling–sliding contact problems

International Journal of Fatigue, 2007

... The tangential stress, which includes the influence of stress intensity factors K I , K II , ... more ... The tangential stress, which includes the influence of stress intensity factors K I , K II , T-stress and constant internal pressure to the crack's surfaces, can be written in polar co-ordinates as [10]: (8) View the MathML source where the tractions View the MathML source and View ...

Research paper thumbnail of Symmetry preserving algorithm for large displacement frictionless contact by the pre-discretization penalty method

International Journal for Numerical Methods in Engineering, 2004

Abstract A three-dimensional contact algorithm based on the pre-discretization penalty method is ... more Abstract A three-dimensional contact algorithm based on the pre-discretization penalty method is presented. Using the pre-discretization formulation gives rise to contact searching performed at the surface Gaussian integration points. It is shown that the proposed ...

Research paper thumbnail of Simulation of crash tests for high containment levels of road safety barriers

Engineering Failure Analysis, 2007

This paper presents the results of computer simulations of road safety barrier behaviour under ve... more This paper presents the results of computer simulations of road safety barrier behaviour under vehicle crash conditions for high containment levels as mandated by the European standard EN 1317. Simulations were performed with the explicit finite element code LS-...

Research paper thumbnail of Post-processing techniques for assessing element distortion errors

Engineering Computations, 1989

Abstract: Finite element meshes can today be used to represent very complex structures because of... more Abstract: Finite element meshes can today be used to represent very complex structures because of high performance hardware and software. Although a very successful contributor to modern engineering analysis, such techniques are prone to certain classes of ...

Research paper thumbnail of Internal structure characterization of AlSi7 and AlSi10 advanced pore morphology (APM) foam elements

Materials Letters, 2014

ABSTRACT The paper presents a detailed geometrical characterization of APM foam elements with sph... more ABSTRACT The paper presents a detailed geometrical characterization of APM foam elements with sphere-like interconnected closed-cell porous structure and integral skin. The influence of the alloying element Si on internal structure (pore size, spatial distribution, sphericity and orientation) for different APM foam element sizes (made of AlSi7 and AlSi10) has been evaluated and quantified using an improved and novel approach based on micro-computed tomography data acquisition.

Research paper thumbnail of Intelligent system for the automatic calculation of stamping parameters

SCOPE & TOPICS Advances in Production Engineering & Management (APEM) is an interdisciplinary ref... more SCOPE & TOPICS Advances in Production Engineering & Management (APEM) is an interdisciplinary refereed academic journal. The main goal of the APEM is to present high quality research developments in all areas of production engineering and production management, as well as their applications in industry and services, to a broad audience of academics and practitioners. In order to bridge the gap between theory and practice, applications and case studies are particularly welcome. For theoretical papers, their originality and research contributions are the main factors in the evaluation process. Fields of interest include, but are not limited to: