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

Application of electronic dental dynamometer in biomechanics

The paper presents a microprocessor force recorder, whose design allows the measurement of occlusal forces on a continuous basis with a maximum frequency of 250 Hz. The electronic dental dynamometer records the results of clinical trials in the form of graphic images and text files which are presented directly onto the computer. The recorded results can be processed digitally, as well as compared with other measurements, resulting in the ability to monitor the progress and potential advances in the treatment of masticatory organ diseases. An important advantage of the proposed solution is the simple and intuitive design. In addition, the dynamometer requires no power coming directly from the electricity network, as it is powered through a 5 V USB port. This feature not only determines the comfort of use, but also the safety as the voltage does not pose a risk to the patient during examination. The results recorded during clinical trials using the electronic dental dynamometer are consistent with those obtained using a calibrated mechanical dental dynamometer

INFLUENCE OF CHANGES IN THE WORKING TEMPERATURE OF FLEXIBLE COUPLINGS ON THEIR STIFFNESS CHARACTERISTICS

This article compares flexible couplings of the spider-type insert, and the tire-type insert. The influences of the volume and hardness of the elastomeric connector on the characteristics of this type of coupling, as well as the course of the change of the stiffness coefficient as a result of changes in the operating temperature, are presented. In drive systems, flexible couplings undergo very frequent changes within a wide range of operating temperatures, which causes a change in the dynamic parameters of the flexible couplings during operation

Numerical identification of the overhead travelling crane’s dynamic factor caused by lifting the load off the ground

Overhead travelling cranes work with intermittent motion, and therefore are most exposed to dynamic loads. In steel constructions, as a result of load pick up from the ground, vibrations of various degrees of intensity are induced, which should be included in crane design. These loads affect both the hoisting mechanisms and load-carrying structures. The aim of this study is the formulation of a phenomenological model of an overhead travelling crane enabling the identification of dynamic factors caused by lifting the load off the ground. The object of the study was 107 overhead travelling cranes with lifting capacities from 5 to 50 tones, designed in the Centre for Research and Development of Cranes and Transport Equipment “Detrans” in Bytom and produced in Poland in the period 1970-2005. Cranes were classified according to the stiffness classes proposed in European standards for crane safety. In this paper, computer simulations are carried out on the basis of a phenomenological model with four degrees of freedom, three of them corresponding to the crane’s structure and one to the hoisted load. The model also allows assumption of the variable stiffness and damping of the steel rope during its shortening. The values of the dynamic factors refer to the various design and dynamic parameters of overhead travelling cranes, formulating appropriate conclusions

Numerical identification of the overhead travelling crane’s dynamic factor caused by lifting the load off the ground

Overhead travelling cranes work with intermittent motion, and therefore are most exposed to dynamic loads. In steel constructions, as a result of load pick up from the ground, vibrations of various degrees of intensity are induced, which should be included in crane design. These loads affect both the hoisting mechanisms and load-carrying structures. The aim of this study is the formulation of a phenomenological model of an overhead travelling crane enabling the identification of dynamic factors caused by lifting the load off the ground. The object of the study was 107 overhead travelling cranes with lifting capacities from 5 to 50 tones, designed in the Centre for Research and Development of Cranes and Transport Equipment “Detrans” in Bytom and produced in Poland in the period 1970-2005. Cranes were classified according to the stiffness classes proposed in European standards for crane safety. In this paper, computer simulations are carried out on the basis of a phenomenological model with four degrees of freedom, three of them corresponding to the crane’s structure and one to the hoisted load. The model also allows assumption of the variable stiffness and damping of the steel rope during its shortening. The values of the dynamic factors refer to the various design and dynamic parameters of overhead travelling cranes, formulating appropriate conclusions

Application of electronic dental dynamometer in biomechanics

The paper presents a microprocessor force recorder, whose design allows the measurement of occlusal forces on a continuous basis with a maximum frequency of 250 Hz. The electronic dental dynamometer records the results of clinical trials in the form of graphic images and text files which are presented directly onto the computer. The recorded results can be processed digitally, as well as compared with other measurements, resulting in the ability to monitor the progress and potential advances in the treatment of masticatory organ diseases. An important advantage of the proposed solution is the simple and intuitive design. In addition, the dynamometer requires no power coming directly from the electricity network, as it is powered through a 5 V USB port. This feature not only determines the comfort of use, but also the safety as the voltage does not pose a risk to the patient during examination. The results recorded during clinical trials using the electronic dental dynamometer are consistent with those obtained using a calibrated mechanical dental dynamometer

Measurement capabilities upgrade of GEM soft X-ray measurement system for hot plasma diagnostics

The paper presents improvements of the developed system for hot plasma radiation measurement in the soft X-ray range based on a Gas Electron Multiplier (GEM) detector. Scope of work consists of a new solution for handling hardware time-synchronization with tokamak systems needed for better synchronization with other diagnostics and measurement quality. The paper describes the support of new modes of triggering on PC-side. There are communication and data path overview in the system. The new API is described, which provide separate channels for data and control and is more robust than the earlier solution. Work concentrates on stability and usability improvements of the implemented device providing better usage for end-user

Measurement capabilities upgrade of GEM soft X-ray measurement system for hot plasma diagnostics

The paper presents improvements of the developed system for hot plasma radiation measurement in the soft X-ray range based on a Gas Electron Multiplier (GEM) detector. Scope of work consists of a new solution for handling hardware time-synchronization with tokamak systems needed for better synchronization with other diagnostics and measurement quality. The paper describes the support of new modes of triggering on PC-side. There are communication and data path overview in the system. The new API is described, which provide separate channels for data and control and is more robust than the earlier solution. Work concentrates on stability and usability improvements of the implemented device providing better usage for end-user