Determination Of Dynamic Loads Research Articles

Determination of dynamic loads in the crane lifting mechanism

Loading and unloading is an integral part of the technological process of construction. To perform these works mostly use cranes of different types.
 To ensure trouble-free operation and increase the reliability of cranes in the calculation of structures and components of their work equipment, it is important to take into account dynamic loads, which are several times higher than static loads.
 Elements of dynamic loads of the crane lifting mechanism are its elastic components - ropes and shafts, which are deformed under the action of loads. The magnitude of this deformation of the elements are taken into account by the coefficients of elasticity or flexibility of linear and torsional or their inverse value - the coefficients of rigidity. These coefficients depend on the linear or angular deformations, respectively.
 Due to the fact that the mechanism of lifting a load consists of a large number of elastic elements, the addition and solution of equations to determine these coefficients becomes a difficult task. In order to simplify the equations and these calculations, the paper recommends the above scheme of calculations according to which the rest of all elements of the mechanism are reduced to its first element (engine). This greatly simplifies the equations to be solved and determines the values ​​of the coefficients of elasticity or stiffness of the elements of the dynamic loads of the mechanism of lifting the load of cranes.
 According to a similar scheme is also determined by the moments of inertia of the mechanism of lifting the load during periods of acceleration and deceleration, the components of the values ​​that affect them. The equations for determining the terms of transients of the lifting mechanism (duration of acceleration and braking) are derived.
 The method of determining the coefficients of elasticity and stiffness of the elements of dynamic loads, moments of inertia, duration of acceleration and deceleration of the lifting mechanism can greatly simplify the solution of complex equations and determine their values ​​with sufficient accuracy.

ДИНАМИЧЕСКАЯ МОДЕЛЬ ГОРИЗОНТАЛЬНОЙ ПЛАНЕТАРНОЙ МЕЛЬНИЦЫ

Issues are considered that are associated with the determination of dynamic loads encountered in moving units of the planetary mill. A horizontal planetary mill was chosen for compiling a dynamic model, as it has a great potential for organizing a closed grinding cycle with continuous loading and unloading of material. Calculation schemes were drawn up in moving units at the moments of the beginning of its operation and the steady movement of the grinding drums. Using the d’Alembert principle, taking into account the geometric parameters of the grinding unit, the reduced moments of inertia and moments of forces, as well as the acceleration time from a state of rest until the carrier reached a steady angular velocity, were determined. From the condition of equality of the power of the reduced moment of forces acting on the link of reduction, and the power of all forces and moments applied to the links of the planetary mill, the initial torque applied to the carrier was determined, which is necessary in the future to determine the power expended both at the moment of starting the mill, and at the time of its stable operation. It is shown that the initial torque depends on the value of the initial angular acceleration, which, in turn, can be different depending on the accepted law for changing the angular acceleration and the acceleration time to the required angular velocity of steady motion. It is also indicated that during the start-up period, the power supplied to the mill is spent on accelerating the rotation of the leading link and on overcoming various resistances such as friction forces in the units of the carrier and grinding drums.

Determination of Dynamic Loads from the Road Surface Acting on the Chassis by Experimental Methods

Chassis is the main structural component of an automobile, which is subjected to the full weight load being suspended. In the process of moving, the vehicle can both move and cut the tree while moving and sweeping the garbage as well as moving water. During the operation,the chassis is subject to dynamic loads depending on the driver and road conditions. The variation of dynamic loads causes fatigue failure to reduce the life of the chassis. Therefore,the determination of dynamic loads as input for chassis durability problem is necessary. This paper presents the research results on the determination of dynamic loads from the road surface acting on the chassis of multipurpose forest fire fighting vehicles by experimental methods. Experiments are performed when vehicles are moving on forest roads, under the actual working conditions of the vehicle.

DETERMINATION OF LOADING FOR A CONTAINER LOCATED ON A FLAT WAGON UNDER VISCO-ELASTIC INTERACTION BETWEEN FITTINGS AND FITTING STOPS

The article deals with determination of the dynamic loading of a universal dry cargo container located on a flat wagon under shunting impacts. In order to decrease the impact loads between the fittings of a container and the fitting stops of a flat wagon under shunting impacts when the impact loads exceed the friction force between the horizontal planes of the fittings and fitting stops, the author proposed to install elastic or viscous elements in the fittings of the container. The mathematical modelling was conducted for determination of the dynamic loads on a container considering the improvements. A 1СС type container located on a 13-4012 flat wagon was chosen as a prototype container. The mathematical model considered displacements of the container located on the flat-wagon at shunting impacts, i.e. displacements of the fittings of the container relative to the fitting stops of the flat-wagon. The modelling was conducted for visco-elastic interaction in the fittings of the container. The solution to the differential equations of motion was made in Mathсad by reducing them to the Cauchy form with subsequent integration by the Runge–Kutta method. The optimal parameters of visco-elastic interaction together with their conformity with the dynamic loads to the container were determined. The strength calculation for the container with consideration of measures regarding improvement and determination of dynamic loads were made. The finite-element method in CosmosWorks was used as a calculation method. It was established that the container capacity at shunting impacts was ensured.The research conducted encourages the development of new generation containers of enhanced performance and better ecological characteristics, and also promotes a higher efficiency of combined transportation.

Определение динамических нагрузок в главном приводе прокатного стана при прокатке полос с оребрением

Определение динамических нагрузок в главном приводе прокатного стана при прокатке полос с оребрением

К ВОПРОСУ КОНТРОЛЯ СКОРОСТНЫХ РЕЖИМОВ ДВИЖЕНИЯ БОЛЬШЕГРУЗНЫХ АВТОПОЕЗДОВ НА ПЕРЕВОЗКАХ МЕТАЛЛОПРОДУКЦИИ В УСЛОВИЯХ ГОРОДА

The paper optimization model of speed mode is presented. Deals with issues of optimization of the motion of heavy trucks at steel products transportations within the urban network. Presented results of the experimental studies allow determination of dynamic loads in the bearing systems

К ВОПРОСУ ОЦЕНКИ ДОРОЖНЫХ УСЛОВИЙ РАБОТЫ БОЛЬШЕГРУЗНЫХ АВТОПОЕЗДОВ НА ПЕРЕВОЗКАХ МЕТАЛЛОПРОДУКЦИИ

In the article the questions of estimation of heavy-load road trains at steel products transportations. Presented results of the experimental studies allow determination of dynamic loads in the bearing systems. Proposed method and model to determine the complex index estimates road conditions

Modeling of Dynamic Loads on the Polished Rod of Pumping Unit in Case of Mulfunction of Rod Pump Operating

The paper presents the results of theoretical modeling of joined movement of pump rods and plunger pump and multiphase flow in a well for determination of dynamic loads on the polished rod of pumping unit. The specificity of the proposed model is the possibility of taking into account for complications in rod pump operating, such as leakage in valve steam, presence of gas and emulsion, incorrect fitting of plunger inside the cylinder pump. The satisfactory agreement of results of the model simulation with filed measurements are obtained.

Determination of dynamic loads transmitted to a hammer foundation

Determination of dynamic loads transmitted to a hammer foundation

Analytical method for determination of dynamic loading in an electric drive armature

Analytical method for determination of dynamic loading in an electric drive armature

Coupled Vibration of Geared Systems

In the design of geared rotating systems in engineering practice a variety of configurations are used, and their torsional vibration has been extensively studied. Detailed analyses of the modes and frequencies of vibration of these systems have been given by Ker Wilson and Nestorides. When the rotating system is rigidly supported, standard methods may be used to obtain the characteristics of free vibration and the response to impressed forces, from which the transmissibility of the gear-box may be calculated. However, there are many applications in which the gearbox is flexibly mounted. The simple example of a geared engine with a flexibly mounted crankcase has been considered by Den Hartog and Butterfield. In some epicyclic gear-box assemblies, elastic elements are introduced between the reactive element and the gear-case to increase the capacity for absorbing impulsive loads and as a means of varying the natural frequencies of vibration'. Harmonic forces acting on the rotors excite coupled vibration of the rotating system and the supporting frame, and Ker Wilson has shown how the natural frequencies and modes of the combined system may be determined by Holzer-type tabular methods. This involves a trial-and-error technique which may sometimes be tedious. Vibration of geared systems may also be excited by the motion of the frame supporting the gear-box, and an analysis of the response is necessary in the determination of dynamic loads.