Preliminary modeling studies of sudden release of a part of the hoist load with using experimental miniature test crane

In the article, the problem of preliminary studies was carried out on an experimental test bench equipped with an experimental set of measurement sensors. Proposed test stand allows to carry out a series of studies on the phenomena of dynamic loads associated with lifting process. The problem of vibration caused by the sudden release of a part of the load was discussed in this paper. This phenomenon can occur either in the case of hoists fitted with gripping devices such as an electromagnet or a standard gripper but also as in the case of failure and loss of cargo part. This phenomenon is important because of the vibration of the supporting structure in the work cycle, they over exploit the structure and contribute to the multiplicity of fatigue cycles. The application of the proposed test stand on a scale enabled an immediate analysis of the data so important in the verification of the phenomenological model of the analyzed lifting mechanism. This approach will allow for the next stage of research, i.e., hybrid analysis, i.e., combining the dynamic model with the FEM model of the girder. The goal is to develop a simple and accurate model for virtualizing solutions designed to reduce the amount of vibration generated by the sudden release of a part of the load

Modeling assumptions influence on stress and strain state in 450 t cranes hoisting winch construction

This work investigates the FEM simulation of stress and strain state of the selected trolley’s load-carrying structure with 450 tones hoisting capacity [1]. Computational loads were adopted as in standard PN-EN 13001-2. Model of trolley was built from several cooperating with each other (in contact) parts. The influence of model assumptions (simplification) in selected construction nodes to the value of maximum stress and strain with its area of occurrence was being analyzed. The aim of this study was to determine whether the simplification, which reduces the time required to prepare the model and perform calculations (e.g., rigid connection instead of contact) are substantially changing the characteristics of the model

MODELLING STUDIES ON THE USE OF ALUMINIUM ALLOYS IN LIGHTWEIGHT LOAD-CARRYING CRANE STRUCTURES

Summary. The article presents the results of numerical analysis whose aim was to compare the basic dynamic and strength parameters of lightweight load-carrying crane structures made of aluminium alloys and steel. The analysis covered the typical construction of workshop cranes with a span of 3 to 5 meters, girders in the form of an I-beam and maximum load capacities amounting to 5 tons. The values of stresses, deflections and natural frequencies were compared and then matched with the masses of the various structures. In the simulation a girder model was used and computed by the finite element method

Modeling the dynamics of cargo lifting process by overhead crane for dynamic overload factor estimation

The essential phenomenon accompanying hoisting machines such as overhead cranes is the occurring of negative vibrations. Due to the characteristic beam type construction of the load carrying structure, they were particularly important in the case of heavy loads, causing considerable stress values, both in the ropes and girder structure. These values are described by dynamic coefficient examined in this study. Because of the problem importance, a different approach to modeling the process of lifting the load is proposed, mainly due to the dynamic model of rope applied. It proposes models of the rope and lifting mechanism, using both the modified Bouc-Wen model as well as a classical model of Kelvin-Voigt as a model of rope in the hoisting mechanism, where the value of dynamic factor has been verified. It helps to specify the multiplicity of overloading the structure and impact of rope modeling method according to its value. The models for the test of hoisting machines proposed in the paper include the modeling of the wire rope in the hoisting mechanism and the influence of ropes modeling method on a dynamic factor

PRELIMINARY STUDIES OF VERTICAL ACCELERATION OF A PASSENGER CAR PASSING THROUGH THE SPEED BUMP FOR VARIOUS DRIVING SPEEDS

The article proposes a phenomenological model of a passenger car. The model includes the biomechanical model of human bodies in the sitting position of Muksian and Nash acting as passengers, while the driver’s weight has been reduced to the concentrated weight of the loading seat. The research carried out in this study consisted of passing the vehicle through a transverse obstacle along the so-called speed bump. Vehicle passes through the threshold at three different speeds: 10km/h, 20km/h, and 30km/h. The purpose of the conducted experiments was to initially estimate the values of accelerations acting especially on the passenger at selected driving speeds. On the basis of conducted tests, it was possible to verify the numerical model of the vehicle overcoming the obstacle on the road. This approach allows the use of the proposed model to verify the forces and accelerations affecting the passenger, specified before any selected specific biomechanical model of the human person, for example, a model of pregnant women in this configuration allows us to estimate the forces and accelerations acting on the embryo while overcoming some obstacles on the road

PRELIMINARY STUDIES OF VERTICAL ACCELERATION OF A PASSENGER CAR PASSING THROUGH THE SPEED BUMP FOR VARIOUS DRIVING SPEEDS

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IMPACT ANALYSIS OF MICRO-JET COOLING FOR STRESS CONCENTRATION IN A CRANE BUMPER DURING A COLLISION

In the structure of crane bumpers, there is a need to join various types of steel. Usually, low-alloy steel structures are used for this purpose, which can be represented by S355J2 steel. The tensile strength of S355J2 low-alloy steel is slightly below 600 MPa, and the tensile strength of S355J2 steel is at the high level of 200 J at ambient temperature. The impact strength of this steel in negative temperatures is also good at over 47 J at -60 °C, so it meets the 6th class of impact toughness. Welding structures, after classic gas metal arc welding (GMAW) processes, meet only the second impact toughness class. An improved GMAW process was used by micro-jet cooling application to raise the mechanical properties of the joints. The microstructure and main properties of the joints were carefully analyzed. The influence of using the new suggested welding process on the various properties of the welds is presented (UTS – ultimate tensile strength, YS – yield strength, Poisson ratio, elongation, Young’s modulus). Then, the effects of tests for use in crane bumper construction were checked by using a hybrid finite element method (FEM) analysis