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EN
The paper concerns the analysis of reliability of three truss towers performed with the system approach. The first stage of the reliability analysis involved determination of the reliability index for trusses while assuming the same reliability of elements. In the second stage, assessment of the reliability was made according to Eurocodes. The impact of the wind load probability distribution and connection types in towers on their reliability was analysed. In the capacity function, the following random variables were taken into account: cross-sectional area, yield strength, modulus of elasticity, minimum moment of inertia, and length of the element.
EN
This paper analyses the changes in the values of the damping coefficient of shock absorbers, depending on the size and distribution of loads in passenger vehicles. The tests were conducted in two stages. During the first stage, the influence of the size of a load in vehicles, and changes in the tyre pressure values on the damping coefficient of shock absorbers was defined. During the second stage, the influence of the changes of the damping coefficient of shock absorbers was researched, depending on the size and distribution of load in passenger vehicles with various suspension systems of front and rear axles, different kerb weights, lengths and wheel bases. Eight variants of load distribution in vehicles were tested. The evaluation of the damping coefficient of shock absorbers was conducted with the EUSAMA method. This paper identified the sizes and distribution of loads in the vehicles of varied structural parameters and tyre pressures on the damping coefficient values of shock absorbers. The test results indicate that when using a vehicle under varied load conditions, there are changes in the damping coefficient of shock absorbers. This may translate directly into the traction characteristics and stability of a vehicle while travelling, and this, in turn, is connected with the vehicle safety. This paper shows the considerable influence of the tyre pressure on the EUSAMA coefficient. The changes in the vehicle loads also influenced the values of the damping coefficient of shock absorbers. The changes in the damping coefficient of shock absorbers were also influenced by the size and distribution of loads in vehicles.
3
Content available Mechanical systems with air spring flexible elements
EN
The purpose of this study was to assess the effectiveness of flexible air-spring systems operating in parallel to share the total load, taking into account installation and in-operation errors. This study presented experimental and calculated characteristics of the air spring flexibility and its dependence on the polytropic index and additional volume. It considered patterns of load distribution between the air springs when they are operating in parallel to share the total load for the case when the air springs were used as the supporting elements for various machines and units, and between transmission lines containing flexible couplings, where air springs were installed as flexible elements.
PL
W pracy omówiono zagadnienia dotyczące wyznaczania współczynników nierównomiernego rozkładu obciążenia w przekładniach zębatych. Zaproponowano metodę wyznaczania korelacji pomiędzy współczynnikami KHβ i KFβ odnoszącymi się odpowiednio do nierównomiernego rozkładu naprężeń stykowych oraz naprężeń u podstawy zęba od zginania w kole zębatym. Zaproponowane rozwiązanie pozwala analizować w zębie odkształcenia i naprężenia w dwuwymiarowej skali, uwzględniając wysokość i szerokość zęba. Otrzymane z zaproponowanego modelu wyniki porównano z rezultatami obliczeń, otrzymanymi zgodnie z zaleceniami według normy ISO, dotyczącymi wyznaczania nierównomierności rozkładu obciążenia. Następnie ustalono obszary zgodności wygenerowanych rozwiązań.
EN
This paper deals with the problem of determining the face load factors for spur gears. The authors propose a method used for determination of the correlation between the KHβ and KFβ factors, related respectively to load distribution due to contact and load distribution due to bending of the gear tooth. The proposed method allows to analyze deformation and stress in two dimensions, taking into account height and width of the gear tooth. The obtained results were compared with the ISO guidelines regarding the face load factors determination and then the regions of compatibility between the methods were analyzed.
5
Content available remote Sposoby przykładania obciążenia zmiennego na konstrukcję płytowo-słupową
PL
W artykule przedstawiono analizę porównawczą wybranych metod przykładania obciążenia zmiennego na konstrukcję płytowo-słupową. Przeanalizowano pięć sposobów rozkładu obciążenia na płytę stropową. Wyniki momentów zginających i przemieszczeń w wybranych punktach porównywano z wartościami ekstremalnymi obliczonymi na podstawie powierzchni wpływu (Wariant 1). Wykonane obliczenia pozwoliły na wskazanie zalecanej metody rozkładu obciążenia zmiennego na płytę stropową w konstrukcji płyta-słup.
EN
The article compares selected methods of live load application to slab-column structures. Five variants of live load distribution on a plane slab are analysed here. The analysis results for the investigated cases are bending moments and displacements at selected points, compared with the extreme values computed by means of influence areas (Variant 1). The calculations made it possible to indicate the recommended method of live load distribution on a flat slab in slab-column structures.
EN
In the cycloidal gear, the torque is transmitted to the planet gears via an eccentric shaft with central bearings mounted on it. A straight-line mechanism is used to output the torque from the planet gears to the output shaft, a mechanism which consists of rotational sleeves mounted on the pins rigidly connected to the output shaft disc. These sleeves roll off in the holes of the planetary wheel. The forces generated in the straight-line mechanism affect the distribution of forces in the cycloid gearing and the amount of force loading the central bearing. The article presents the influence of the number of bolts of the straight-line mechanism on the load distribution in the cycloidal gear. The research carried out with the simulation program has shown that the smaller the number of pins, the greater the fluctuation of the force acting in the central bearing and the greater unevenness of force distributions in the cycloidal gear. This unevenness may cause a decrease in fatigue life of the meshing and central bearings.
PL
W obiegowej przekładni cykloidalnej moment napędowy jest przekazywany na koła obiegowe za pośrednictwem wałka mimośrodowego z osadzonymi na nim łożyskami centralnymi. Do wyprowadzenia momentu obrotowego z kół obiegowych na wał wyjściowy służy mechanizm równowodowy, który tworzą tuleje osadzone obrotowo na sworzniach sztywno powiązanych z tarczą wału wyjściowego. Tuleje te odtaczają się w otworach koła obiegowego. Siły powstające w mechanizmie równowodowym wpływają na rozkłady sił w zazębieniu cykloidalnym oraz na wielkość siły obciążającej łożysko centralne. W artykule przedstawiono wpływ liczby sworzni mechanizmu równowodowego na rozkład obciążeń w przekładni cykloidalnej. Badania przeprowadzone za pomocą opracowanego programu symulacyjnego pokazały, że im mniejsza liczba sworzni, tym większe wahania siły działającej w łożysku centralnym i większa nierównomierność rozkładów sił w zazębieniu cykloidalnym. Nierównomierność ta może być przyczyną zmniejszenia trwałości zmęczeniowej zazębienia oraz łożysk centralnych.
EN
A new method has been developed for predicting the load distribution along the thread portion of a bolt and nut connection. The calculated results were validated by comparison with three-dimensional finite element analysis and Yamamoto’s method. It was shown that the load distribution predicted by the model in this paper was in good agreement with the results from finite element model, and the load ratio on the first thread by the prediction model and finite element model was slightly larger than the results from Yamamoto’s method. In addition, the results of calculation and finite element analysis indicated that the decreasing of the lead angle could improve the load distribution, the increasing of the length of thread engaged could significantly improve the load bearing capacity of the first thread, and the adopting of a material with low stiffness for the nut with respect to the bolt could improve the load distribution slightly.
EN
Although automated machines are widely used in composite structure manufacturing, manually drilled holes are usually necessary due to spatial constrains and holes with perpendicularity errors are occasionally generated as a result. Considering the anisotropic properties of composite material, the influences of hole perpendicularity error on mechanical performances of composite joints are different from those of isotropic material. In this study, the effects of hole perpendicularity error on load distribution in single-lap double-bolt composite joints are discussed. A finite element model is first developed and verified both by analytical and experimental results. Parametric studies are then carried out taking into consideration bolt torque and hole perpendicularity error, represented by hole tilting direction and tilting angle. It is found that the hole tilting direction significantly affects on load distribution in composite joints. Although the loads taken by bolts are not significantly affected, it may make one composite plate take more than 60% of total loads. In addition, the influences of tilting angle on load distribution can be ignored in most cases, and as for the bolt torque, it is to enhance the influence of hole tilting direction.
EN
In a PV-dominant DC microgrid, the traditional energy distribution method based on the droop control method has problems such as output voltage drop, insufficient power distribution accuracy, etc. Meanwhile, different battery energy storage units usually have different parameters when the system is running. Therefore, this paper proposes an improved control method that introduces a reference current correction factor, and a weighted calculation method for load power distribution based on the parameters of battery energy storage units is proposed to achieve weighted allocation of load power. In addition, considering the variation of bus voltage at the time of load mutation, voltage secondary control is added to realize dynamic adjustment of DC bus voltage fluctuation. The proposed method can achieve balance and stable operation of energy storage units. The simulation results verified the effectiveness and stability of the proposed control strategy.
EN
This paper describes the influence of road transport on urbanization and the transport of oversized loads. There is an increasing interest in oversized transport and urban development. In this developmental context, it is necessary to transport heavy construction machinery, infrastructure elements, pipes for gas pipelines and waterworks, or even rails to create roads for rail transport. For this purpose, the transport of loads exceeding standard parameters (16.50 m in length, 2.55 m in width, 4.00 m in height and 40 Mg in mass) is used. Oversized traffic has many obstacles on the roads, such as low bridges and viaducts, narrow roads, poor technical condition of roads, road works and low-permeability roundabouts.
EN
This article is dedicated to the subject of gearboxes, with a specific focus on the load distribution on the tooth. The aim of the study was to review the selected solutions and methods that can contribute to aligning the load on the width of the tooth. The structure and operation of each solution are described in detail. The paper presents the possible benefits of using the described solutions.
PL
W pracy zawarto rozważania dotyczące stosowania przypadków normowych obciążenia śniegiem dachów płaskich z attykami według normy Eurokod 1. Przedstawiono sposób wyznaczania obciążeń śniegiem zgodny z normą PN-EN 1991–1-3:2005 wraz z późniejszymi zmianami. Przeprowadzono analizę porównawczą wytężenia stropodachów dla trzech przypadków obciążenia. Analizę porównawczą przeprowadzono numerycznie z wykorzystaniem oprogramowania systemowego ABC 6.15. Analizie poddano płaski stropodach, monolityczny, żelbetowy, krzyżowo-zbrojony. Przedstawiono wyniki momentów zginających dla trzech przypadków obciążenia śniegiem. W pracy odniesiono się również do typowych stosowanych w Polsce stropodachów prefabrykowanych typu TERIVA.
EN
The present work contains considerations related to application of norm cases, related to snow-load on flat roofs with attics, according to the provisions of the Eurocode 1 norm. The snow-load determination method has been presented. The method has been developed in line with the PN-EN 1991-1-3:2005 norm, along with the further amendments. In the further part of the article, the summarizes the comparative stress analysis for flat roofs, for three load cases. The analysis contained in the article has been carried out numerically, with the use of the ABC 6.15 software. A flat monolithic, ferro-concrete crossreinforced roof is the subject of that analysis. The work also presents the results for the bending momentum values, for three snow-load cases. The work also makes a reference to the typical TERIVA flat roofs that are widely and commonly applied in Poland.
PL
W artykule przedstawiono rozkład obciążeń od parcia ośrodka sypkiego na ścianę przy niecentrycznym opróżnianiu komory silosu zaliczanego do klasy oceny oddziaływań AAC3 (zgodnie z PN -EN 1991-4). W silosach opróżnianych na dużych mimośrodach (mimośród opróżniania większy niż 0,25 średnicy wewnętrznej silosu) należy uwzględnić dodatkowy przypadek obciążenia na ściany silosu, niezależny od parcia lokalnego przy napełnianiu i opróżnianiu. Przeprowadzono analizę geometrii kanału przepływu w komorze silosu przy niecentrycznym opróżnianiu, na podstawie której obliczono kąt określający strefę przepływu wybranych ośrodków sypkich.
EN
The load distribution caused by the bulk pressure on the wall of a cylindrical silo chamber (class AAC3) subject to an eccentric discharge, based on the PN-EN 1991-4, was presented in the paper. For silos emptied eccentrically, when eccentricity is greater than one quarter of the silo internal diameter, an additional load on the silo walls should be taken into account. This unsymmetrical load should be considered independently of the local pressure during filling and emptying. An analysis of the flow channel geometry in the silo chamber during eccentric discharge was carried out. Results of the analysis were used as the basis for calculations of the angle specifying the flow zone for chosen bulk solids.
14
Content available remote Analysis of Crushing Process by Flat and Profiled Crushing Plates
EN
The principle of operation of the lever crushers (jaw crushers) consists of crushing the feed solids between the fixed and the moving jaw. In crusher’s designing stage, it is important to know the load acting on the machine and energy expended on the crushing of raw materials (feed). Determination of force (load) distribution in the working space of lever crusher is the basis for the design of these types of machines (e.g. bodies, drive shafts, pitman). The current methods of determining the crushing forces relate to model processes which are an idealization of real processes. This paper presents experimental studies on the crushing proces of three different materials by flat and profiled crushing plates. Results show a significant influence of the shape of used plates on loads acting in the crusher’s working space.
15
Content available Load distribution in the worm meshing
EN
The paper presents a theoretical analysis of deflections of circular and rectangular cantilever plates of an elastically built-in edge. The problem has been solved using the finite difference method. A method of determination of load distribution between two plates being in contact along an arbitrary line has been presented. Different shapes of these plates constitute models of mating of cylindrical and globoidal worm meshings. To verify the presented theory of searching for load distributions along the contact lines in these meshings, experimental investigations with the freezing of stresses in the cylindrical worm meshing have been carried out. Directions of investigations that would specify further theoretical considerations over load distribution in globoidal gear meshings have been indicated.
PL
Przedstawiono wpływ sposobu odwzorowania sztywności poprzecznej przęsła z belek typu Płońsk, obciążonego normowym modelem taboru drogowego, na rozdział poprzeczny obciążenia, deformacje przęsła, przemieszczenia pionowe i momenty zginające w belkach. Porównano wyniki obliczeń i sformułowano wnioski dotyczące przydatności poszczególnych siedmiu modeli do projektowania.
EN
Lateral distribution of the standard design load determined based on seven different numerical models are presented and discussed taking into account their usefulness to design of the bridges of “Płońsk” type or similar types.
PL
W artykule przedstawiono rozwiązanie pozwalające na ograniczeniu wad i niedogodności w znanych rozwiązaniach konstrukcji obudowy, a także zwiększenie jej nośności i jej odporności na nierównomierny rozkład obciążeń. Wymagania takie spełnia obudowa nowej generacji wykonana w sposób modułowy, z zastosowaniem dodatkowego sprężenia między poszczególnymi modułami zarówno w osi pionowej, jak i poziomej. Proponowana obudowa wykorzystana może być między innymi w podziemnych zbiornikach retencyjnych. W artykule przedstawiono przykład zastosowania takiej obudowy na podstawie projektu koncepcyjnego zbiornika retencyjnego w kopalni węgla kamiennego.
EN
This paper presents a solution allowing reducing defects and drawbacks in the known solutions of the lining's structure and also increasing in its bearing capacity and its resistance to uneven load distribution. Such requirements are satisfied by a new generation lining, constructed in a modular manner, with the use of an additional compression between the individual modules in both the vertical and horizontal axis. The proposed lining can be used, inter alia, in underground retention reservoirs. The article presents an example of the use of such a lining on the basis of the conceptual design of a retention reservoir in a hard coal mine.
PL
W artykule zaprezentowano i porównano ze sobą rozkłady obciążenia wewnętrznego w łożyskach wieńcowych, które zabudowano w różnych podzespołach wsporczych. Wskazano punkty nadmiernego obciążenia przenoszonego przez łożysko, które pracuje w podzespołach wsporczych niezapewniających odpowiedniej ostoi dla łożyska wieńcowego.
EN
In the article was presented and compared between themselves distribution of inner load in slewing bearing. It was built from different subassemblies. It was shown the points of excessive overload transferred by the bearing It is working in subassemblies which not providing the appropriate frame for the slewing bearing.
EN
The paper presents a computational model of the load distribution between elements in a planetary roller screw. The idea of the model is to consider the deformations of rolling elements as deformations of rectangular volumes subjected to shear stresses. The contact deformations of threads and the deformations of screw and nut cores are taken into account by a properly chosen shear modulus. This modulus is computed on the basis of stiffness determined using the finite element method. Based on the relation between displacements and forces differential equations are obtained. The solution to these equations is a hyperbolic function that illustrates the load distribution on the threads between cooperating elements. The following considerations are carried out to assess the suitability of the analytical model for the preliminary design and analysis of this type of transmissions.
PL
Scharakteryzowano podstawowe właściwości przęseł płytowych mostów betonowych. Omówiono obliczenia dwuprzęsłowego skośnego wiaduktu płytowego za pomocą dziewięciu różnych modeli obliczeniowych uproszczonych i dokładnych. Wyniki obliczeń porównywano z odpowiednimi wynikami badań. Sformułowano pewne ogólne i szczegółowe wnioski dotyczące analizowanych modeli obliczeniowych na podstawie wspomnianego porównania.
EN
The basic properties of the spans of slab concrete bridges are briefly characterized. Calculations of two-span continues slab skew bridge using nine various models, simplified and accurate, are performed. The results of calculation are compared with the relevant test results. Some particular and general conclusions concerning the analyzed models are formulated based on the above comparison.
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