About
39
Publications
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Introduction
Pawel Dunaj currently works at the Department of Mechanical Engineering, West Pomeranian University of Technology, Szczecin. Pawel does research in Mechanical Engineering. Their current project is 'Vertical lathe of light construction'.
Additional affiliations
December 2019 - June 2024
March 2024 - May 2024
March 2023 - May 2023
Education
October 2015 - September 2019
February 2014 - June 2015
October 2010 - February 2014
Publications
Publications (39)
The paper presents the process of designing a lightweight vertical lathe with a steel-polymer frame. The purpose of using such a frame was to increase the stability of machining. As part of the study presented in this paper, polymer concrete was developed to provide a significant increase in the damping of steel structures (increase in the modal da...
The static stiffness of machine tools is one of the key parameters influencing the accuracy of dimensions, shape, and relative positioning of the surfaces of workpieces being machined. This paper presents an analysis of the effect of the stiffness of individual structural components on the resulting stiffness of a prototype vertical lathe with a st...
The paper presents the finite element model updating algorithm based on a substructuring method. The proposed algorithm enables model order reduction of selected substructures in order to reduce the necessary computational time. The model updating procedure consist of two levels: (i) local updating, based on updating the selected substructures and...
Predicting the dynamic properties of welded machine tool frames of is of key importance at the design stage. However, it is a complex issue, especially when damping is concerned. The paper presents the method of modeling welded structures based on finite element method and model updating. According to proposed procedure the finite element model of...
The performance of a machine tool is directly influenced by the characteristics of the floor, subsoil, and their interaction with the installed machine. Installing a machine tool in its operational environment poses a distinct challenge that bridges mechanical and civil engineering disciplines. This interdisciplinary issue is often overlooked withi...
Sandwich panels are key components of many lightweight structures. They are often subjected to time-varying loads, which can cause various types of vibrations that adversely affect the functionality of the structure. That is why it is of such importance to predict the dynamic properties of both the panels and the structures made of them at the desi...
Modeling the dynamic properties of wood and wood-based composites is a challenging task due to naturally growing structure and moisture-dependent material properties. This paper presents the finite element modeling of plywood panels' dynamic properties. Two panels differing in thickness were analyzed: (i) 18 mm and (ii) 27 mm. The developed models...
The optimal combination of machine tool support and foundation type is vital for high precision manufacturing. However, there is limited knowledge and few models available for predicting the behavior of a machine tool, including its operational environment. The study presents the estimation of the machine tool-support-foundation-subsoil system para...
There is a constant need to predict the dynamic properties of composite materials already at the design stage. A particularly attractive tool for achieving this goal is mesoscale finite element modeling. This paper presents the mesoscale modeling of the dynamic properties of polymer concrete. The method is based on finite element modeling and subst...
Structural damping largely determines the dynamic properties of mechanical structures, especially those whose functioning is accompanied by time-varying loads. These loads may cause vibrations of a different nature, which adversely affects the functionality of the structure. Therefore, many studies have been carried out on vibration reduction metho...
The paper presents the finite element modeling of the dynamic properties of a delta robot attached to a steel frame. A distinguishing feature of the proposed modeling method is the application of the Guyan reduction method in modeling of frame foundations. The frame in question was analyzed in two variants: (i) without attached robot and (ii) with...
Honeycomb core sandwich panels are crucial components of many lightweight structures nowadays. These structures are often subjected to a time-varying loads, which may cause vibrations of various nature. These, in turn, may result in the loss of functionality of the structure. Therefore, it is crucial to predict the dynamic properties of these struc...
Thin-walled, box section, steel beams are the basic components of machine tools, vibratory machines, production lines and other structures subjected to time-varying loads. Therefore, it is desirable to shape their dynamic properties. It can be achieved by filling these components with polymer concrete. The polymer concrete filling increases stiffne...
This paper presents a method for simplified modeling of bearing nodes of a lathe spindle using the finite element method. The proposed modeling methodology is based on the use of an orthotropic material model, which is used to reflect the stiffness properties of the bearing, both in the radial and axial directions. The modeling results have been ex...
This article is a continuation of previous research in which we analysed the effect of deflections and elastic deformations caused by unsupervised support conditions on the measurements of geometrical deviations of large crankshafts. Supporting the shaft using a set of rigid supports at the same height limited the ability to detect deviations in th...
This article presents the results of finite element analyses of the influence of reaction forces on stresses and strains at the contact points of the rollers of prism supports with cylindrical surfaces of the main journals of large-sized crankshafts. The analyses of strains and stresses, as well as the depth of their occurrences, in the case of the...
Designing machine toolsfor in situ machining is a challenging task due to their unique structures and restrictive functional requirements. Such a machine tool should be characterized by low mass, adequate machining accuracy and high machining stability.The paper presents the design of an ultra-light, axisymmetric, portable machine tool for in situ...
This article presents a multi-criteria analysis of the errors that may occur while measuring the geometric deviations of crankshafts that require multi-point support. The analysis included in the paper confirmed that the currently used conventional support method-in which the journals of large crankshafts rest on a set of fixed rigid vee-blocks-sig...
A new approach has been taken to the problem of straight and bent bar buckling, where bar buckling is considered as a function of axial displacement of one end. It was assumed that the length of a bar being buckled at any instant of buckling is the same as that of a straight bar, regardless of the size of axial displacement of one end of the bar. B...
The free vibration model of a steel-polymer concrete beam based on Timoshenko beam theory is presented in this paper. The results obtained on the basis of the model analysis, describing values of the natural frequencies of the beam, were compared with the results obtained by the solution of the model formulated on the basis of the classical Euler-B...
At the stage of designing a special machine tool, it is necessary to analyze many variants of structural solutions of frames and load-bearing systems and to choose the best solution in terms of dynamic properties, in particular considering its resistance to chatter. For this reason, it is preferred to adopt a low-dimensional calculation model, whic...
The paper presents a new way to conduct passive elimination of vibrations consisting of covering elements of structures with low dynamic stiffness with polylactide (PLA). The PLA cover was created in 3D printing technology. The PLA cover was connected with the structure by means of a press connection. Appropriate arrangement of the PLA cover allows...
This paper presents a method for modeling the dynamic properties of steel-polymer concrete beams, the basic structural components of machine tools, assembly lines, vibratory machines, and other structures subjected to time-varying loads during operation. The presented method of modeling steel-polymer concrete beams was developed using the finite el...
The presented paper focuses on issues related to the modeling of steel-polymer concrete frames for machine tools. The activities carried out and the proposed models were based on an analysis of the physicality of the modeled phenomena. The most important achievements presented in the paper include development of a coherent method for modeling steel...
Designing machine tool bodies is a difficult task due to their complexity and requires a thorough knowledge of the phenomena accompanying the cutting process. It has therefore been a common practice to base design on proven generational structures, where the vast majority of machine tool bodies are assembled from materials such as steel or gray cas...
Designing machine tools is an extremely complicated process, requiring thorough knowledge from the constructors in terms of statics, dynamics, contact mechanics, etc. Therefore, it is necessary to support this process by analyzing their models. However, only on the basis of experimentally identified models, reliable information about the object can...
This article presents the methodology for modeling the stiffness of a machine tool load-bearing system using the finite element method. A new, simplified model of stiffness of the linear guide with a preload based on equivalent contact model was proposed. An equivalent contract model was developed where the ball was replaced with four rod elements...
Paper presents a method of simplifications used over numerical studies on dynamic properties of a hydraulic loader crane. Simplification concerns hydraulic actuators and allows for a significant reduction in the time of building model and calculations. Modal analysis of a loader crane using the finite element method, for both complex and simplified...
The damping of steel welded machine tool bodies is usually insufficient in a perspective of functional properties of the machine. Therefore, methods are sought to increase their ability to dissipate energy. One of the solutions is to fill steel welded body with a composite material based on an epoxy resin. Such a structure should maintain its good...
The article presents results of a diagnostic procedure aimed at detecting the case of loss of stability of a knee-type milling machine prototype and proposing remedial methods. To this end, operational research was followed by modal tests of the machine prototype. The operational research identified the mechanism behind the vibration and a detailed...
The article presents results of both experimental and FEM model-based investigations on chatter phenomena that occur in the end milling process. On the basis of chatter symptoms observed during machining, the mechanism of its occurrence has been identified. Then, a FEM model has been built to indicate machine tool elements responsible for loss of s...
In presented paper, an analysis of model order reduction (MOR) techniques applied to steel beams filled with a composite material is presented. This research concerns specific construction solutions used in technological machines. The analyzes concern three reduction methods: Guyan reduction also referred as static condensation, Craig-Bampton reduc...
In presented paper, an experimental investigation on dynamic properties of a machine tool basis was conducted. A process of modal parameters estimation was carried out and as a result modal model was built. Significant mode shapes from the viewpoint of rocking and self-excited vibrations was identified and briefly described. According to fact that...
Modelling of structural elements using materials with significantly different parameters is a demanding issue, mainly due to the possibilities of commercial computing software. The paper presents a method of modelling the damping properties of a component consisting of a steel beam filled with a composite material. The compatibility of the modellin...
Paper present results of experimental investigations on dynamic properties of rope threading lathe TAE 45N. Prototype of this uniquely designed machine tool was delivered for the tests focused on finding dominant mode shape. Influence of the domi-nant mode on the cutting process is determined. Significant velocity and acceleration of headstock, dur...
Paper presents results of experimental investigations on dynamic properties of loader crane Hiab XS 111 HI DUO. Investigations were conducted on full scale loader crane in two its configurations. Main goal of work was finding a reason of significant vibrations amplitude of its tip – flexibility of jibs or relative movement of stiff beams. Interpret...