Wyniki wyszukiwania - BazTech

1

Stan techniczny podłoży ściennych a jakość elewacji

Krause P.

Materiały Budowlane

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2016

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nr 9

4--5

2

The influence of road surface unevenness on tyre rolling resistance

Ejsmont J., Ronowski G., Taryma S., Świeczko-Żurek B.

Archiwum Motoryzacji

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2015

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Vol. 70, no. 4

35--46, 121--132

EN

The geometric characteristics of road surface substantially affect the interaction between tyre and road. Depending on pavement texture wavelength, the texture chiefly affects tyre/road friction, rolling resistance, interior and exterior noise, tyre wear, and ride comfort. The article presents results of investigations on the influence of road surface unevenness on the rolling resistance of passenger car and truck tyres. The tests were carried out on a roadwheel facility being a part of the test equipment of the Automotive Tyre Testing Laboratory of the Gdańsk University of Technology, where a specially made replica road surface with a sinusoidal unevenness profile was mounted on the drum, and on a test road. The unevenness profile under test was characterized by a wavelength of 0.8 m and amplitude of 10 mm, which corresponded to the road surface type commonly referred to as “washboard”. The objective of the experiments was to ascertain whether the increase in rolling resistance observed on uneven road surfaces is exclusively caused by an increase in the energy losses in suspension system damping elements or the energy losses in the tyre actually rise as well. The tests revealed that, on the sinusoidal road surface as defined above in comparison with the “Safety Walk” smooth sandpaper like surface, the rolling resistance of passenger car tyres grew by about 10 % and rolling resistance of truck tyres increased about 30 %.

PL

Parametry geometryczne nawierzchni w sposób decydujący wpływają na współpracę opony samochodowej z drogą. W zależności od długości fali nierówności oddziaływanie tekstury koncentruje się na przyczepności, oporze toczenia, hałasie wewnętrznym i zewnętrznym, zużyciu opony oraz komforcie jazdy. Artykuł prezentuje wyniki badań wpływu równości nawierzchni na opór toczenia opon do samochodów osobowych i ciężarowych. Badania prowadzone były na maszynie bieżnej stanowiącej wyposażenie Laboratorium Badania Opon Samochodowych Politechniki Gdańskiej na której zamontowano specjalnie wykonaną replikę nawierzchni drogowej o sinusoidalnym przebiegu nierówności oraz na drodze. Badane nierówności miały długość fali 0.8 m i amplitudę wynoszącą 10 mm co odpowiada nierównościom popularnie nazywanym "tarką". Celem eksperymentów było stwierdzenie, czy obserwowany na nierównych nawierzchniach wzrost oporu toczenia wiąże się jedynie ze wzrostem strat w elementach tłumiących zawieszenia, czy też wzrastają również straty w samej oponie. Badania wykazały, że na opisanej nawierzchni sinusoidalnej w stosunku do gładkiej nawierzchni Safety Walk opory w oponach samochodów osobowych wzrastają o około 10%, a dla opon do samochodów ciężarowych o około 30%.

3

New possibility of objective evaluation of yarn appearance

Moučková E., Jirásková P.

Autex Research Journal

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2012

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Vol. 12, no. 1

7--13

EN

The possibility of new and objective evaluation of yarn appearance wound on the board is described. A statistical method which has previously been used for the evaluation of surface unevenness of flat textile - semivariograms is used. The yarn board appearance is converted into a grey-scale image and the fluctuation in degrees of greyness between square fields in the image is evaluated by semivariogram. This method was applied on standard yarn boards from the standard CSN 80 0704 in addition to real yarn boards. The results of semivariograms constructed from a simulated ideal appearance of yarn on the board are discussed with the aim of introducing an ideal case behaviour of semivariograms. The possibility of using this function for the objective evaluation of yarn board appearance is also discussed.

4

New method for the evaluation of woven fabric unevenness

Jiraskova P., Moučková E.

Autex Research Journal

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2010

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Vol. 10, no. 2

49--54

EN

Unevenness of woven fabric results from irregularity of the yarn used as well as from the process of its manufacture(weaving). A periodical and non-periodical yarn irregularity shows itself in the flat textile by known effects - themoiré effect, cloudiness, and stripiness. It is possible to predict the appearance of flat textiles from measured values of yarn mass irregularity and their characteristic functions (a spectrogram, a variance-length curve). The evaluation of surface unevenness of woven fabrics is done not directly but by judging their appearance, most often subjectively. For evaluation of flat textile appearance, it is also possible to use a so-called area-variation curve. The curve can be constructed on the basis of analysis of a woven fabric image either by a special program, created by J. Militky (Technical University of Liberec) in the programming environment Matlab, or by means of image analysis. By these methods it is possible to evaluate an image of real flat textile as well as a simulated image from an apparatus for yarn irregularity measurement. The woven fabric image is in grey scale. The variation coefficient of greyness degrees expresses the unevenness of flat textiles. In the experiment both real woven fabric images and simulated appearances of woven fabric, obtained by means of the apparatus Uster Tester IV, are evaluated by the methods mentioned above. The acquired area-variation curves are compared with each other and compared with visual evaluation of the woven fabric image. It was found that area-variation curves show only marked unevenness of woven fabric.