Theoretical Analysis of Factors Affecting Ultimate Nominal Load of Reinforced Concrete Axially Loaded Short Squire Columns (Pu) Comparing use Prokon Program

One of this theoretical study, parameters that affecting the ultimate load capacity of the axially loaded column are studied. The parameters such as compressive strength of concrete and steel reinforcement ratio. Throughout study a different value of each factor will be assumed. Then the nominal load-carrying capacity of axially loaded column was calculated for these different factors parameters according using the simplified methods provided in (ACI-318- 14) building code requirement for structural concrete and Prokon Program. It is observed that increasing the compressive strength of concrete result in improving the ultimate load capacity. Using compressive strength of concrete more than 40MPa which results in increasing of (Pu) from (2362kN) to(5918KN) . On other hand The total area of longitudinal reinforcement bars (AST), and the gross area of concrete section (Ag) have a significant effects also on increasing of (Pu) value but not as (Fcʹ).

Improvement of Turboshaft Restart Time Through an Experimental and Numerical Investigation

Inflight shutdown of one engine for twin-engine helicopters have proven beneficial for fuel consumption. A new flight mode is then considered, in which one engine is put into sleep mode (the gas generator is kept at a stabilized, sub-idle speed by means of an electric motor, with no combustion), while the second engine runs almost at nominal load. The ability to restart the engine in sleep mode is then critical for safety reasons. Indeed, the certification of this flight mode involves ensuring a close-to-zero failure rate for in-flight restarts as well as a fast restart capability of the shutdown engine. In this paper, the focus is made on improving the restart time of the shutdown turboshaft engine. Fast restart capability is necessary for flight management reasons. Indeed, in case of a failure of the engine operating close to nominal load while the other one is in sleep mode, there is no more power available and the helicopter can lose up to 15–20 meters per second during autorotation. The restart time becomes a critical parameter to limit the loss of altitude. In the configuration studied, the fast restart is achieved thanks to the electric motor designed to deliver a high torque to the gas generator shaft. This electric motor is powered by an additional battery, more powerful than the conventional one dedicated for standard restarts. The aim of the paper is to assess the potential restart time saving using an approach combining test rig data analysis and numerical results generated by a thermodynamic model able to simulate at very low rotational speed. A gas turbine engine starting process is composed of two main phases: the light-up phase and the acceleration phase. It is important to understand the detailed phenomenology of these two phases as well as the various sub-systems involved, first to highlight the influencing parameters of both phases and then to establish an exhaustive listing of the possible time optimizations. From the test rig campaign, conducted at Safran Helicopter Engines on a high power free turbine turboshaft engine, we are able to accurately break down the phases of the start-up sequence, which helps us to identify what steps of the sequence worth shortening. With the engine performance thermodynamic model, we can then use the information gathered from the test rig analysis to further predict how to save time and to give guidelines for developing new control strategies. The results of this study show that a fast restart going from sleep mode to max power speed can be up to 60% faster than a conventional restart going from sleep mode to idle speed. This is significantly faster, especially if one takes into account the higher final speed targeted by the fast restart.

EXPERIMENTAL RESEARCHES OF THE COMBINED UNIT FOR SMALL SOIL TREATMENT

. The article presents the results of experimental studies on soil preparation for sowing winter crops on unpaired predecessors with a combined unit. The design of a combined unit with an adaptive set of working bodies has been developed. As a result of the research, agrotechnical and energy indicators of the working process were established. The nominal load of the unit together with the tractor is determined.

Realization of a Fully Optically Accessible Medium Speed Large Bore Engine Using a Fisheye Optic

To address one of the main environmental concerns, the engine out emissions, an enhanced understanding of the combustion process itself is fundamental. Recent optical and laser optical measurement techniques provide a promising approach to investigate and optimize the combustion process regarding emissions. These measurement techniques are already quite common for passenger car and truck size engines and significantly contribute to their improvement. Transferring these measurement techniques to large bore engines from low to high speed is still rather more uncommon especially due to the bigger challenges caused by the engine size and thus much higher stability requirements and design effort for optical accessibility. To cover this new field of research a new approach for a medium speed large bore engine was developed using a fisheye optic mounted centrally in the cylinder head to design a fully optically accessible engine test bench. This new approach is detailed with a test setup layout and a stability concept consisting of cooling systems and the development of a suitable operation strategy based on simulation and experimental verification. The design of this single cylinder engine with 350mm bore and 440mm stroke providing 530kW nominal load at 750 rpm was tested up to 85% nominal load in skipped fire engine operation mode. The measurements of the flame chemiluminescence of a dual fuel combustion of the diesel gas type present proof of the feasibility of the new design as a starting point for future systematic studies on the combustion process of large bore engines.

SELECTING THE VALUE OF THE STOCK RATIO WHEN SETTING UP SAFETY FRICTION CLUTCHES

It is shown that the coefficient of safety friction clutches is not enough to transfer the nominal load of the machine without slipping in cases when the coefficient of friction decreases to a minimum value. It is established that the existing theory of calculation and design of safety clutches contains an erroneous position that the nominal torque of the machine is constant and does not change in time. This leads to an increase in the probability of occurrence of unmotivated actuations of safety friction clutches with a decrease in the coefficient of friction below the average value.

DEVELOPMENT OF A METHOD FOR SELECTING THE SHAPE OF THE LOAD CHARACTERISTIC THE ADAPTIVE FRICTION CLUTCH WITH A SEPARATE POWER CIRCUIT

The main provisions of the method for selecting the form of the load characteristic of the AFM with a separate power circuit are formulated. The method involves taking into account the nominal load, the total mass of the drive, the value of the gain of the adaptive friction clutch with a separate power circuit and the accuracy of its operation, as well as recommendations for the choice of the second design version of the clutch. The choice of the type of adaptive friction clutch, taking into account the load characteristics, is based on the different load capacity and accuracy of operation, which correspond to these forms.

Calculation and design of adaptive friction second-generation couplings (first version)

The method of calculating an adaptive friction clutch with a separate power closure (the first option) is given.The features of calculating the values of the clutch control device parameters to ensure the highest accuracy of operation at a given nominal load capacity are shown. Explanations are given when calculating the values of the control device parameters depending on the shape of the load characteristic of the coupling.

TECHNOLOGICAL APPLICATIONS OF ADAPTIVE FRICTION CLUTCHES

It is shown that the largest part of the existing adaptive friction clutches is suitable for use only in light and medium-loaded drives of machines, and their smallest part can be used in drives of machines operating at highly stabilized load on the Executive body. It is proven that short drives with a single-threaded kinematic chain it is advisable to use the adaptive friction clutch having relatively low accuracy and limited nominal loading capacity, in drives with long single-threaded kinematic chain, appropriate use of adaptive friction couplings with relatively low accuracy and with a higher nominal load capacity.

Equations of a magnetoelectric valve motor for loop closures of the stator winding

The article considers the differential equations of a switched permanent magnet motor in which a short-circuit fault occurred in one or more turns in one of parallel stator winding branches. Owing to the occurred asymmetry of the phase quantities, symmetrical line-to-line voltages at the stator winding terminals are assumed. It is shown that turn-to-turn short-circuit faults give rise to non-sinusoidal and imbalanced phase currents and voltages at the nominal load torque on the shaft, and it should be noted that initially, a growth of the frequency and ratios of currents in the phases with an increase in the number of short-circuited turns are observed, after which the phase currents tend to decrease (with a continuing growth in the current through the short-circuited loop), and the rotor stalling occurs. The growth of motor rotation frequency and decrease of its overloading capacity take place due to a growth in the demagnetizing effect of armature reaction caused by the current through the short-circuited stator winding turns.