Synthesis and Properties of High Tilted Antiferroelectric Esters with Partially Fluorinated Alkoxyalkoxy Terminal Chains

Novel chiral esters with partially fluorinated alkoxyalkoxy terminal chains are described. Their phase transition temperatures, enthalpies, and electrooptical properties are reported. A helical pitch in pure compounds and their mixtures based on selective reflection of light is also characterized

Investigation of significant parameters during abrasive waterjet turning

This paper presents an investigation of abrasive waterjet turning (AWJT). The purpose of the article was to investigate significant parameters of the turning process and to evaluate their impact on the turning product. The influence of the traverse speed, the rotational speed, and the relative position of the jet to the specimen (lateral jet shift) were investigated. Based on the previous research done in this field, the multi-pass tangential turning method was selected. Rotational speed does not seem to have a significant impact on the AWJ turning process. However, the relative position of the jet is a key parameter for improving the efficiency of the process. Increasing the lateral jet shift causes the volume of the material removed to increase until the optimal impact angle is reached. These findings need to be extended in order to adjust AWJT. Without these improvements, a comparison of jet to traditional technologies is inappropriate.Web of Science1416art. no. 438

Notes on the abrasive water jet (AWJ) machining

The aim of the research was to investigate changes of abrasive grains on metals observing the kerf walls produced by the Abrasive Water Jet (AWJ). The microscopy observations of the sidewalls of kerfs cut by the AWJ in several metal materials with an identical thickness of 10 mm are presented. The observed sizes of abrasive grains were compared with the results of research aimed at the disintegration of the abrasive grains during the mixing process in the cutting head during the injection AWJ creation. Some correlations were discovered and verified. The kerf walls observations show the size of material disintegration caused by the individual abrasive grains and also indicate the size of these grains. One part of this short communication is devoted to a critical look at some of the conclusions of the older published studies, namely regarding the correlation of the number of interacting particles with the acoustic emissions measured on cut materials. The discussion is aimed at the abrasive grain size after the mixing process and changes of this size in the interaction with the target material.Web of Science1422art. no. 703

Study of stochastics of load in aspect of defining the fatigue life of a multipurpose set for planting potatoes

W artykule zawarto opis studium stochastyki obciążeń. Badania przeprowadzono na potrzeby oszacowania trwałości zmęczeniowej agregatu do sadzenia ziemniaków. Określono wpływ obciążeń na naprężenia w wybranych miejscach konstrukcji. Przeprowadzono analizę widmową sygnałów i zidentyfikowano źródła pochodzenia poszczególnych pasm częstotliwości naprężeń. Obliczono funkcję koherencji zwyczajnej pomiędzy badanymi sygnałami oraz wyznaczono transmitancje widmowe układu. Zebrane dane są podstawą do dalszych rozważań na temat wytrzymałości zmęczeniowej konstrukcji.The article presents a study of stochastics loads. The research was performed for calculation of fatigue life of potato planter. The effect of loads on stress at selected locations on the structure was calculated. Spectral analysis was carried out and sources of frequency bands of stress were localized. Coherence between signals was calculated and spectral transmittance of the system was computed. The obtained information shall be used for estimating the fatigue life of machine

The issue of fatigue evaluation of agricultural machines shown in a multirole unit

W artykule zawarto opis analizy zmęczeniowej wybranego przypadku eksploatacyjnego kombajnu melioracyjnego, przeprowadzonej w komputerowym środowisku symulacyjnym. Opisano techniki, którymi posłużono się w procesie predykcji trwałości zmęczeniowej, i uzasadniono wybór konkretnych metod. W wyniku opracowanej na potrzeby badań własnej procedury obliczeń zlokalizowano obszary, w których naprężenia przekraczają wartości dopuszczalne. Zaimplementowane w konstrukcji wzmocnienia pozwoliły na zaprojektowanie konstrukcji o wymaganej niezawodności.The article presents an overview of the fatigue analysis of a multi-role unit, carried out in a computer simulation environment. The techniques which were used in the prediction of durability were described. The author's own procedure for fatigue calculation of a multi-role unit was developed. By that means areas where stresses exceed the limit values were found. It allows implementing changes in the structure so the structure is designed with the required reliability

The issues of designing of construction features of the internal combustion cam engine

On the pages of the article described cam-piston mechanism developed as an alternative to piston crank mechanism. The main feature of this mechanism is that the piston is dwell in the TDC by the 30°CA and thus allows combustion of the fuel in constant volume. Authors presented the process of designing an analytical cam. The starting point for the calculation was the displacement of piston graph and the limits of acceleration and velocity values obtained. The results of strength calculations of the cam with regard to fatigue problems are also presented. Calculations were carried out in order to reduce the weight of the cam. For this purpose, the Finite Element Method was used

Simulation study of virtual model of centrifugal clutch with adjustable torque power transfer in aspect of heat flow

W artykule przedstawiono sposób modelowania zespołów roboczych dla potrzeb prowadzenia analiz cieplnych na przykładzie wirtualnego modelu sprzęgła odśrodkowego z regulowanym momentem przenoszenia mocy. Omówiono przebieg obliczeń numerycznych występującego przepływu ciepła na drodze konwekcji i przewodzenia. Wyjaśniono szczegółowo przebieg ich realizacji oraz wykonano szereg analiz porównawczych, na podstawie których oszacowano wpływ charakterystycznych stałych na gęstość strumienia ciepła.In this paper results of thermal analysis of conception a virtual model of centrifugal clutch with adjustable torque power transmission were presented. Numerical calculations of heat transfer, including convection and conduction of heat were presented. Details of the calculations progress and comparative analysis, that allowed heat flow density estimation, for different kind of heat exchange were explained

Approximation to the reduced stress tensor components using the plane stress state

W artykule opisano metodę wyznaczania grubość elementów typu "cienka powłoka" stosowanych w badaniach wytrzymałościowych przeprowadzanych za pomocą Metody Elementów Skończonych. Wyprowadzono równanie wykorzystujące składowe tensora płaskiego stanu naprężenia. Równanie jest zmodyfikowaną formą hipotezy Hubera-Misesa-Hencky'ego (H-M-H). Dla prostych przypadków wytrzymałościowych pozwala wyznaczyć bezpośrednio grubość blachy lub grubość ściany profilu stalowego.In this study, the thickness calculation method of thin-shell elements used in FEM strength analysis was described. An equation was brought out using the tensor components of two dimensions stress state. The equation is a modified form of the H-M-H hypothesis. This equation allows to compute the wall thickness in simple strenght cases in the first iterative step

Analiza procesu mieszania cieczy nienewtonowskich wspomagana symulacją numeryczną CFD

The article describes the problem of mixing process analysis of non-Newtonian fluids supported by CFD numerical simulation. To introduce the analysis method of the mixing process a series of numerical experiments was carried out exemplified by vessel equipped with two types of agitator with rotary coil. There was shown velocity magnitude distribution in two perpendicular cutting planes and velocity profiles for both constructional agitator solutions. Moreover, it was provided comparative analysis, which showed impact of viscosity and rotation velocity of agitator on nature of the mixing process.W artykule przedstawiono problematykę analizy procesu mieszania cieczy nienewtonowskich z wykorzystaniem symulacji numerycznej CFD. Celem prezentacji sposobu analizy zjawisk towarzyszących mieszaniu przeprowadzono serię eksperymentów numerycznych na przykładzie zbiornika wyposażonego w dwa warianty mieszadła wężownicowego. Przedstawiono mapy prędkości chwilowych mieszanej cieczy w wybranych płaszczyznach oraz profile prędkości dla obu rozwiązań konstrukcyjnych mieszadeł. Ponadto, dokonano analizy porównawczej obrazującej wpływ lepkości cieczy oraz prędkości obrotowej zespołu mieszającego na charakter procesu mieszania

Evaluation of the possibility of occurrence of selected damage to a car engine turbocharger using the event tree analysis (ETA)

The subject of the article is the identification of factors behind the incorrect operation of a car turbocharger that, in longer perspective, lead to the damage of the device. Due to the operating principle and design features, the device works with many engine systems – intake, exhaust, lubrication systems and also, increasingly more often, with the cooling system. A multitude of relations, complexity, and working conditions are reasons due to which the device is sensitive to disturbances of quality parameters of the working media (e.g. oil). In the article based on the selected causes of damage of turbochargers, we focused on the following initiating event, concerning the bearings lubrication system, which is clogged oil strainer. The authors aims at performing an analysis allowing to increase the detectability of emerging malfunctions that lead to deterioration of operating conditions of the device. For this task tool such as ETA (Event Tree Analysis) was used. It is a tool for assessing system and process safety. It facilitates detecting potential risks, as well as relations existing between actions or events. This method explores the path from the initiating event to the outcome (most often representing the immobilization of the tested object), with particular emphasis on intermediate stages affecting the technical condition of the object. Unlike the FTA analyses, which have a deductive nature, the ETA analysis is inductive. The analysis of the obtained results, supported with validation by means of ETA, allowed proving that, given the current state of knowledge and advancements in technology, it is possible to apply additional sensors for monitoring the operation of a turbocharger. The proposed modifications were considered minor design changes that significantly increase the reliability of the device