Wyniki wyszukiwania - Biblioteka Nauki

1

Roughness Prediction Based on a Model of Cochlear Hydrodynamics

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Vencovskỳ V.

Archives of Acoustics

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2016

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tom Vol. 41, No. 2

189--201

EN

The term roughness is used to describe a specific sound sensation which may occur when listening to stimuli with more than one spectral component within the same critical band. It is believed that the spectral components interact inside the cochlea, which leads to fluctuations in the neural signal and, in turn, to a sensation of roughness. This study presents a roughness model composed of two successive stages: peripheral and central. The peripheral stage models the function of the peripheral ear. The central stage predicts roughness from the temporal envelope of the signal processed by the peripheral stage. The roughness model was shown to account for the perceived roughness of various types of acoustic stimuli, including the stimuli with temporal envelopes that are not sinusoidal. It thus accounted for effects of the phase and the shape of the temporal envelope on roughness. The model performance was poor for unmodulated bandpass noise stimuli.

2

Effect of thermomechanical modification of Scots pine (Pinus sylvestris L.) wood on machine sanding efficiency

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Gruszczyński D. , Szymanowski K.

Annals of Warsaw University of Life Sciences - SGGW. Forestry and Wood Technology

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2022

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tom No. 118

74--84

EN

Effect of thermomechanical modification of Scots pine (Pinus sylvestris L.) wood on machine sanding efficiency. The aim of this study was to investigate the effect of thermomechanical modification of pine wood (Pinus sylvestris L.) on the efficiency of machine sanding. For this purpose, pine wood samples (undensified and densified) were subjected to mechanical sanding. The effect of the modification on the mass loss in the sanding process was investigated and the quality of the obtained surface was examined. Roughness parameters Ra and Rz were used as criteria for the quality of the sanded surface. The study was carried out for three different grit sizes of sanding paper. It was found that the thermomechanical modification of Scots pine wood had a statistically significant effect on the mass loss during sanding and the roughness of the obtained surface. Wood samples subjected to thermomechanical compaction were characterised by lower susceptibility to sanding measured on the basis of weight loss and lower surface roughness.

PL

Wpływ termomechanicznej modyfikacji drewna sosny zwyczajnej (Pinus sylvestris L.) na wydajność szlifowania maszynowego. Celem pracy było zbadanie wpływu termomechanicznej modyfikacji drewna sosnowego (Pinus sylvestris L.) na wydajność szlifowania maszynowego. W tym celu próbki drewna sosny zwyczajnej (natywne oraz zagęszczane) poddano szlifowaniu mechanicznemu. Zbadano wpływ modyfikacji na ubytek masy w procesie szlifowania oraz zbadano jakość uzyskanej powierzchni. Jako kryteria jakości szlifowanej powierzchni przyjęto parametry chropowatości Ra i Rz. Badania przeprowadzono dla trzech różnych ziarnistości papieru szlifierskiego. Stwierdzono, że termomechaniczna modyfikacja drewna sosny zwyczajnej wpływa istotnie statystycznie na ubytek masy podczas szlifowania i chropowatość uzyskanej powierzchni. Próbki drewna poddane zagęszczaniu termomechanicznemu charakteryzowały się mniejszą podatnością na szlifowanie mierzoną na podstawie ubytku masy i niższą chropowatością powierzchni.

3

Roughness of three types of gravity disturbances and their correlation with topography in rugged mountains and flat regions

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Tenzer R. , Vajda P. , Hamayun H.

Acta Geophysica

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2009

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tom Vol. 57, no. 3

657-679

EN

We investigate the roughness of and the correlation with topography of the observed, topographically corrected (T), and bathymetrically and topographically corrected (BT) gravity disturbances. The numerical investigation is carried out for the gravity disturbances at the Earth's surface and for the upward continued gravity disturbances at different altitudes. The area of study comprises a rough part of the Canadian Rockies surrounded by flat regions. The smoothest at the Earth's surface are the BT gravity disturbances. The evolution of roughness with altitude shows an interesting phenomenon, diverse for the three types of gravity disturbances. The correlation with topography over the study area of the observed gravity disturbances is bellow 0.6, and of the BT gravity disturbances approximately -0.6. The largest absolute value, of about -0.75, is found between the topography and the T gravity disturbances. This large negative correlation indicates a presence of the isostatic compensation in mountainous regions of the Canadian west coast.

4

Numerical modelling of Shliomis model based ferrofluid lubrication performance in rough short bearing

100%

Munshi M. M. , Patel A. R. , Deheri G.

Journal of Theoretical and Applied Mechanics

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2019

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tom Vol. 57 nr 4

923--934

EN

This paper has attempted to scrutinize the bearing performance of a rough short bearing assisted by a ferrofluid with the help of numerical modelling of the Shliomis model. The transverse roughness is calculated stochastically by averaging the Christensen and Tonder models. A non-zero mean is assumed for the probability density function for the random variable that determines the roughness of the bearing which is symmetrical. This attempt is made to create a more pragmatic and applicable situation. Expressions that can signify a dimensionless form of pressure and bearing load carrying capacity are found using Reynolds’ equation. The load carrying capacity equation is then solved numerically with the help of Simpson’s 1/3 rule to analyze the impact on the bearing system. From the graphical representation, it can be concluded that ferrofluid lubrication based on the Shliomis model can significantly neutralize the negative effects of the bearing roughness on its load carrying capacity.

5

Chropowatość powierzchni po przecinaniu stali na tokarce nożem typu NNPb

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Wieczorowski K. , Tomkowiak P.

Zeszyty Naukowe Politechniki Poznańskiej. Mechanika

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2003

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tom Nr 49

77-88

PL

W artykule przedstawiono wyniki badań chropowatości powierzchni prętów stalowych przecinanych na tokarce nożem NNPb. W procesie technologicznym dużej liczby przedmiotów osiowo-symetrycznych o średnicach nawet do 100 mm istotną operację stanowi odcięcie wykonanego fragmentu lub gotowego wyrobu od pręta zamocowanego w uchwycie tokarki. Z uwagi na poszerzenie powstającego wióra odcinanie przedmiotu stanowi istotne zagrożenie dla chropowatości powierzchni odcinanych. Z uwagi na niewłaściwą chropowatość tych powierzchni znaczna liczba wyrobów osiowo-symetrycznych wymaga dodatkowej obróbki powierzchni po odcięciu. Określono współczynnik poszerzenia wióra w funkcji prędkości skrawania i kształt powierzchni natarcia ostrza noża wpływający na zmianę przekroju poprzecznego wióra. Pokazano strukturę powierzchni po przecinaniu ostrzem noża o płaskiej i specjalnie ukształtowanej powierzchni natarcia. Wskazano możliwości wyeliminowania uszkodzenia warstwy wierzchniej przez zmianę stereometrii ostrza noża przecinaka.

EN

The results of research of roughness after cut-off operation on the turning machine with using cutter type NNPb have been presented in the paper. Cut-off operation is often essential operation in the technological process of manufacturing of axial symetrical machine parts with diameters even to o 100 mm. It is the operation of cutting off of made fragment or of ready article from the shaft fixtured in lathe chuc. The essential problem of this operation can be so big roughness of machined surface because of chip widening. Regarding inappropriate surface roughness considerable number of axial symmetrical machine parts must be additionally machined after cut-off operation. Coefficient of chip widening versus the cutting speed has been determined. The shape of rake face of cutter edge influencing on the change of chip lateral section has been elaborated. The structure of surface after cut-off operation with using cutter with flat rake face and with special shapped rake face has been shown. The possibilities of elimination of surface layer damage on the way of cutter edge stereometry changes have been indicated.

6

Zastosowanie uogólnionych krzywych L2 sklejanych do wyznaczania linii średniej profili chropowatości

100%

Janecki D. , Cabaj M.

Przegląd Mechaniczny

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2007

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tom nr 9 supl.

115-118

PL

W pracy zaprezentowano zastosowanie uogólnionych krzywych L2 sklejanych do wyznaczenia linii średniej profilu chropowatości. Zasadniczą różnicą pomiędzy filtrem wykorzystującym krzywe sklejane opisanym w literaturze a przedstawionym w pracy jest przyjęcie, że odstęp pomiędzy węzłami krzywej jest dużo większy od odstępu próbkowania profilu. Dzięki temu wskaźnik uwarunkowania równań służących do wyznaczania parametrów filtru nie zależy od odstępu próbkowania, a liczba tych równań jest niewielka. Pokazano, że w przypadku gdy w funkcjonale definiującym parametry krzywej sklejanej nie jest uwzględniona kara za energię zgięcia krzywej, odpowiednie tłumienie filtru uzyskujemy, gdy odstęp pomiędzy węzłami krzywej jest dokładnie dwa razy mniejszy od długości odcinka elementarnego. Jeśli uwzględnimy koszt energii zgięcia, to już w przypadku, gdy odległość pomiędzy węzłami jest równa 1/6 długości odcinka elementarnego, otrzymujemy filtr praktycznie stacjonarny, a jego charakterystyka częstotliwościowa nie odbiega od charakterystyki filtru zaproponowanego przez Krystka. Zaproponowany filtr całkowicie eliminuje efekt brzegowy.

EN

L2 - splines were applied to determine the mean line of a roughness profile. The major difference between the filter using splines, which is described in literature, and the filter described in the paper lies in the fact that the distance between spline nodes is much bigger than the profile sampling interval. Owing to this, the conditioning factor of equations applied to determine the filter parameters does not depend on the sampling interval, and the number of such equations is small. If the functional defining the spline parameters does not include the penalty for curve bending energy, the filter can be attenuated properly if the interval between the spline nodes is exactly twice as small as the cut off length. If the cost of the bending energy is taken into account, we obtain a practically stationary filter for a case when the distance between nodes is equal to one sixth of the cut off length. In this case, the filter frequency characteristic is not much different from the one proposed by Krystek. The analyzed filter is able to eliminate the boundary effect completely.

7

Testing the tightness of a square joint between oak wood elements

100%

Dobrowolska E. , Karwat Z. , Kupiec D.

Annals of Warsaw University of Life Sciences - SGGW. Forestry and Wood Technology

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2019

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tom No. 107

139--148

EN

Testing the tightness of a square joint between oak wood elements. The study was carried out to determine the tightness of square joints between elements made of oak wood. To determine the degree of tightness of these joints, a device measuring the swelling pressure of oak wood under the influence of water humidification was designed. Checking the tightness of joints was carried out for surfaces obtained by machining through: grinding, milling, machine planing and manual planing. Contact angles at the phase boundary wood-water and their roughness achieved as a result of machining were also determined. During the wood swelling pressure test, the values of the preload of square joints were changed. The analysis of the results showed that the tightness of the square joint is influenced mainly by the roughness of the surface obtained as a result of machining and the size of the force of the initial load exerted on the moistened surfaces.

PL

Badanie szczelności połączenia na styk elementów z drewna dębowego. W pracy przeprowadzono badanie szczelności połączeń na styk elementów wykonanych z drewna dębowego. Do ustalenia stopnia szczelności tych połączeń zaprojektowano urządzenie, mierzące ciśnienie pęcznienia drewna dębowego pod wpływem nawilżania wodą. Sprawdzanie szczelności połączeń przeprowadzono dla powierzchni uzyskanych w wyniku obróbki skrawaniem poprzez: szlifowanie, frezowanie, struganie grubościowe maszynowe i strugiem ręcznym. Określono również kąt zwilżania wodą powierzchni i ich chropowatość osiąganą w efekcie obróbki skrawaniem. W czasie badania ciśnienia pęcznienia drewna zmieniano wartości wstępnego obciążenia połączeń stykowych. Analiza wyników wykazała, że na szczelność połączenia na styk ma wpływ przede wszystkim chropowatość powierzchni uzyskana w rezultacie obróbki skrawaniem oraz wielkości siły wstępnego obciążenia wywieranego na nawilżane powierzchnie.

8

Uwarunkowania i ograniczenia cyfrowego pomiaru nierówności profili powierzchni

100%

Boryczko A.

Mechanik

|

2010

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tom R. 83, nr 12

957-962

PL

Pomiar zdeterminowanych wartości nierówności profili powierzchni wyrażanych cyfrowo jest złożonym problemem interdyscyplinarnym, który ma istotne ograniczenia techniczne i metrologiczne, często niezauważane w praktyce pomiarowej i analizie ich wyników. Aby spełnione były różne uwarunkowania zależne od charakteru nierówności oraz celu i założeń badania powierzchni, należy przyjąć odpowiednie cyfrowe parametry pomiaru profili powierzchni przed pomiarami. W artykule podano uwarunkowania i usystematyzowano ograniczenia pomiaru nierówności powierzchni w szerokoczęstotliwościowym ujęciu składowych profili.

EN

Explained are the constraints to the surface roughness measurements in wide-frequency profile components depiction.

9

Surface evaluation during the grinding process using acoustic emission signal

100%

Sutowski P.

Journal of Machine Engineering

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2012

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tom Vol. 12, No. 4

23--34

EN

The hereby article presents results of experimental tests which prove the possibility of indirect evaluation of the grinded object's quality with the application of monitoring and analysis of selected acoustic emission signal (AE) registered during the machining process. As the grinding process is carried out and the grinding wheel wear progresses, the acoustic emission signal value is shaped adequately to the workpiece surface quality changes. The binding descriptor of changes of roughness profile and material residual stresses is the RMS value of the acoustic emission signal and in particular the statistical features that characterize the distribution of values contained in the signal sample in relation to the average value. The analysis results indicate that the acoustic emission signal is a convenient indicator for evaluation of stresses cumulated in the surface layer of the material and in selected surface geometrical structure parameters.

10

Distribution of roughness and waviness components of turned surface profiles

100%

Boryczko A.

Metrology and Measurement Systems

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2010

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tom Vol. 17, nr 4

611-620

EN

The paper presents a spectral formulation of surface profile irregularity in a wideband frequency range for roughness, waviness and shape components along the measured length. A unique distribution of roughness and waviness components is proposed, according to the nature of their origination in the course of machining with tools of defined cutting edge, as distinct from standard filtration in measurements of surface irregularities. Differences resulting from both formulations are outlined as well as the method of determining the frequency of component separation for surface roughness and waviness.

11

Roughness characterization of well-polished surfaces by measurements of light scattering distribution

100%

Zhenrong Z. , Jing Z. , Peifu G.

Optica Applicata

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2010

|

tom Vol. 40, nr 4

811--818

EN

According to vector scattering and scalar scattering theory, the relationship of BRDF (bidirectional reflectance distribution function) of light scattering from micro-rough surface with TIS (total integrated scattering) is analyzed. Roughness statistical characterization such as RMS (root mean square), PSD (power spectral density) function are deduced by TIS of polished surface. Based on the light scattering measurement theory, an automatic measure system of light scattering with one dimensional scanning method is built, BRDF of two kinds of polished surfaces (silica surface and Ag reflector) have been measured. PSD of two surfaces has been given by light scattering measurements, roughness characterization of two surfaces has been compared with the data tested by profile meter. The results show that the light scattering measurement method has great application prospects as regards nondestructive measurement for polishing surfaces.

12

Ocena chropowatości przewodów kanalizacyjnych z tworzyw sztucznych

100%

Lebiedowski M.

Gospodarka Wodna

|

2002

|

tom Nr 12

522-524

PL

W artykule poddano analizie wpływ wartości szorstkości przewodów z tworzyw sztucznych na sprawność hydrauliczną podczas grawitacyjnego transportu ścieków. Podano przykłady wyrobów rurowych i deklarowane przez producentów wartości parametru szorstkości. Oceniono wpływ tego parametru na sprawność hydrauliczną rur PEHD/PP, stosując zalecane metody projektowania.

EN

The paper analysis the influence of the surface roughness of sewers made of plastics on the hydraulic efficiency of the gravitational transport of waste waters. There are presented examples of pipes and values of parameter of roughness being declared by the producers. The impact of that parameter on the hydraulic efficiency of pipes PEHD/PP has been estimated using the recommended methods of planning.

13

Effect of plasma cutting parameters upon shapes of bearing curve of C45 steel surface

100%

Skoczylas A. , Zaleski K.

Advances in Science and Technology. Research Journal

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2015

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tom Vol. 9, nr 27

78--82

EN

The article presents the results of studies on the effect of plasma cutting technological parameters upon the shape of bearing curves and the parameters of the curve. The topography of surface formed by plasma cutting were analyzed. For measuring surface roughness and determining the bearing curve the appliance T8000 RC120 – 400 by Hommel-Etamic was used together with software.

14

Separation Of Non-Periodic And Periodic 2D Profile Features Using B-Spline Functions

100%

Janecki D. , Cedro L. , Zwierzchowski J.

Metrology and Measurement Systems

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2015

|

tom Vol. 22, nr 2

289--302

EN

The form, waviness and roughness components of a measured profile are separated by means of digital filters. The aim of analysis was to develop an algorithm for one-dimensional filtering of profiles using approximation by means of B-splines. The theory of B-spline functions introduced by Schoenberg and extended by Unser et al. was used. Unlike the spline filter proposed by Krystek, which is described in ISO standards, the algorithm does not take into account the bending energy of a filtered profile in the functional whose minimization is the principle of the filter. Appropriate smoothness of a filtered profile is achieved by selecting an appropriate distance between nodes of the spline function. In this paper, we determine the Fourier transforms of the filter impulse response at different impulse positions, with respect to the nodes. We show that the filter cutoff length is equal to half of the node-to-node distance. The inclination of the filter frequency characteristic in the transition band can be adjusted by selecting an appropriate degree of the B-spline function. The paper includes examples of separation of 2D roughness, as well as separation of form and waviness of roundness profiles.

15

The study of the surface quality of the thin wall bearing units to rolls roller seats pipe conveyor

100%

Michalik P. , Zajac J. , Fabianova J. , Mital D.

Advances in Science and Technology. Research Journal

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2017

|

tom Vol. 11, no 2

192--197

EN

The article deals with the study of surface roughness of thin-walled houses bearing rollers for roller mills. The size and shape of the rear end housing was designed in order to measure the surface roughness of the inner cylindrical bearing surface with a wall thickness of 4, 5 and 6 mm. For comparison the roughness was measured also on the wall with a thickness 26 mm. The welded housing and the base plate was clamped in the machine vice jaw with a width of 150 mm. Material components bearing small house has been fine-grain weld able steel bearing S355. For finishing the hole with a diameter of 40 mm, a tool with a diameter of 32 mm was used with three cutting blades SDXT09M405R MM. Spindle speed was 1350 rev / min. Tool feed speed was 850 mm / min. The surface roughness was measured with a Mitutoyo SJ 400th.

16

The application of universal cnc machine tool for spur gears manufacturing

100%

Skoczylas L. , Tomczewski L.

Advances in Science and Technology. Research Journal

|

2013

|

tom Vol. 7, nr 19

75--78

EN

The article introduces two variants of making spur gears by using universal CNC machine tools with universal shank cutter. The measurement of the chosen parameters of geometric structures of gear tooth surface were carried out as well as their comparison was made.

17

Perceived roughness of two simultaneous harmonic complex tones

100%

Miśkiewicz A. , Rogala T. , Szczepańska-Antosik J.

Archives of Acoustics

|

2007

|

tom Vol. 32, No. 3

737--748

EN

Two experiments were carried out to determine the dependence of perceived roughness on the frequency ratio of two simultaneous harmonic complex tones. In the first experiment, the frequency ratios of the tone pairs corresponded to 35 within-octave intervals of various musical tuning systems. In the second experiment 12 intervals were used; six of them ranged from 10 cents below to 10 cents above an equally-tempered fourth and the other six encompassed a similar range centred around the equally-tempered fifth. In both experiments the amount of roughness was assessed by absolute magnitude estimation. Results show that roughness considerably varies with the frequency ratio of a pair of harmonic complex tones, which is a well-known phenomenon. A new finding, that is in contrast to published theories of roughness, is that equally-tempered intervals produce less roughness than their counterparts based on integer frequency ratios. This effect is attributed to slow beats that arise between the harmonics of two complex tones when the frequency ratio of an equally-tempered interval slightly departs from integer ratio. Such beats, heard as fluctuations, impart a smooth character to the sound.

18

Modelling the behaviour of a contact layer between the workpiece and a locator

100%

Maciolka P. , Jedrzejewski J.

Journal of Machine Engineering

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2008

|

tom Vol. 8, No. 3

42--53

EN

The assurance of high precision alignment of workpieces with low stiffness requires thorough knowledge about the phenomena taking place in the contact area under the influence of forces exerted by actuators. It is indispensable to utilise the model of a contact and deformations taking place in it. In order to solve the problem of contact, the contact geometry was modelled by means of a flat and rough surface model based on stereometric measurements, as well as by means of the finite element method (FEM). In a FEM method, a spherical structure of the surface layer was assumed and only one zone was taken into consideration, i.e. 0.4.Rt (maximum surface roughness). Zone structure allows easy changing of mechanical properties of material during the introduction of data defined by a strengthening curve in the plastic region. The possibility of expanding the model by consecutive zones allows taking into consideration the physical properties in complex analyses of the surface layer. This paper presents the problem of contact related to the alignment and fixing process, a model of contact deformations between a flat and a rough surface, as well as the algorithm for determining the model of a surface profile according to the bearing ratio curve.

19

Surface quality research for selective laser melting of Ti-6Al-4V alloy

100%

Król M. , Tański T.

Archives of Metallurgy and Materials

|

2016

|

tom Vol. 61, iss. 3

1291--1296

EN

One of the innovative technology of producing the components is Selective Laser Melting (SLM) belongs to additive manufacturing techniques. SLM technology has already been successfully applied in the automotive, aerospace and medical industries. Despite progress in material flexibility and mechanical performances, relatively poor surface finish still presents a significant weakness in the SLM process. The scope of the present article is the study the influence of selective laser melting parameters such as laser power, scanning speed, exposure time and hatch spacing through additive manufacturing as well as the orientation of the model corresponding to the laser beam on the surface characteristic of the components made from Ti-6A1-4V alloy. By using optimized process parameters, a low surface roughness can be obtained. In research, the machine for the selective laser melting of metal powders Renishaw AM 125 device was used. Based on experiment plan, 32 models were produced, which were examined to define the surface roughness and thus represent an influence of process parameters and the orientation on the model surface quality. The article discusses the fundamental factors determining the roughness that gives invaluable knowledge to improve the surface quality of SLM parts.

20

Influence of Single-Stage and Duplex Shot Peening on Surface Roughness and Residual Stresses in Al Mg5 Mn1 Sc0,8 Zr0,4 Alloy

100%

Byczkowska P. , Sawicki J. , Januszewicz B. , Stegliński M.

Archives of Metallurgy and Materials

|

2018

|

tom Vol. 63, iss. 1

505--511

EN

Conventional shot peening (SP) is cheap surface treatment widely used to enhance fatigue life of mechanical components [3,4]. Basically, it is shooting small particles (shots) on the surface of the sample. However, the process itself is so complex that a lot of companies are not able to optimally employ it due to the amount of parameters that must be controlled all at the same time. The duplex process consists in two stages of shot-peening treatment. The first one consist of shot-peening with spherical cast steel shots or cut wire shots. During the second stage the samples processed in stage one were subject to shot-peening with glass beads. In this work, RSA-501 aluminium alloy was shot peened using shots of different material and diameter and tested using a measurement of residual stresses and surface roughness. Tests and studies conducted so far on RSA-501 aluminium alloy demonstrate that bombardment by a treatment medium in the form of glass beads or shots of various shapes and diameters induces permanent plastic deformation of the surface layer. The roughness achieved after the shot-peening process was determined for each treatment medium. The largest value of Ra parameter was achieved for cut wire shots and this result is consistent with the above-mentioned theoretical knowledge. This medium is the most aggressive one to the surface being treated primarily due to the sharp edges of shots. The duplex process was successful in obtaining higher values of compressive stresses in surface layer than values achievable in conventional single-stage shot peening process.