Improving the dependability of light vented foundations exposed to vibration load on frost soils

Aim. Today, dynamically-loaded foundations of process equipment often prove to be oversized with significantly overestimated values of stiffness, mass and material consumption. Therefore, reducing the costs and time of construction of gas pipeline facilities, especially on permafrost, is of relevance to PJSC Gazprom. One of the primary ways of solving this problem is installing gas pumping equipment on light vented support structures. The disadvantage of such structures is the low vibration rigidity. A method [1] is proposed for improving the vibration rigidity of a foundation subjected to vibration load. The simulation aims to improve the dependability of light vented foundations by studying vibration displacements of foundations with attached reinforced concrete panels depending on the thermal state of frost soils, parameters of the attached panels and connectors. Methods. Vibration displacements of a foundation with an attached device were identified using the finite element method and the improved computational model of the foundation – GCU – soil system. Results. Computational experiments identified the vibration displacements of the foundation in the cold and warm seasons for the following cases of reinforced concrete plates attached to the foundation: symmetrical and non-symmetrical; at different distances; through connectors with different stiffness parameters; with additional weights; frozen to the ground. Conclusions were made based on the results of simulation of vibration displacements of foundations with an attached device in cold and warm seasons. Conclusion. The presented results of computational experiments aimed at improving the vibration rigidity of light foundations by using method [1] show sufficiently good indicators of reduced vibration displacements of the foundation. Thus, in the case of symmetrical connection of four reinforced concrete panels in summer, the reduction of vibration displacements is 42.4%, while increased stiffness of the connectors, attachment of additional weights and freezing of reinforced concrete panels into the ground will allow reducing the vibration displacements of the foundation up to 2.5 times. However, it should be noted, that applying the findings in the process of development of project documentation and construction of foundations requires R&D activities involving verification and comparison of the obtained results of numerical simulation with a natural experiment.

Numerical Study on the Mechanical Properties of Transmission Tower K-Joints under Cyclic Loading

During the vibration of a transmission tower, the joints will be subjected to a reciprocating load. To obtain the accurate state of the transmission tower under the load, the mechanical properties of the joints under the vibration load must be considered. In this paper, the mechanical properties of typical K-joints in transmission tower structures are studied by numerical simulation. The failure mode of the K-joint under cyclic loading is also analyzed. The mechanical properties of the K-joint are discussed from the aspects of hysteretic characteristics, stiffness degradation, energy dissipation capacity, and ductility evaluation, and the influencing factors are discussed. The results show that the failure mode of the K-joint is related to the bolt grade and steel strength. When analyzing K-joints, the moment-rotation hysteresis curve should be combined with the realistic parameters of joints to consider the hysteretic behavior of the K-joint. The results provide a theoretical reference for the accurate modeling of transmission towers.

Studying the interaction of a reservoir with an ideal compressible fluid with an elastic half-space

We solve in a flat formulation the problem of harmonic oscillations for a basin with an ideal compressible fluid on an elastic half-space exposed to a localized surface vibration load. The problem reduces to an integral equation (IE) of the first kind for the amplitude of the contact hydrodynamic pressure with a kernel that depends on the difference and the sum of arguments. The IE was solved by the factorization method. A semi-analytical method is presented for determining the main parameters of the contact interaction in hydroelastic systems «liquid-soil» taking into account the effect of natural and man-made vibration loads on them. This makes it possible to identify the conditions for the occurrence of dynamic modes that are dangerous for the construction integrity and to estimate their frequencies range depending on defining characteristics of the system.

Dynamic Stall Characteristics of the Bionic Airfoil with Different Waviness Ratios

A dynamic stall will cause dramatic changes in the aerodynamic performance of the blade, resulting in a sharp increase in the blade vibration load. The bionic leading-edge airfoil with different waviness ratios, inspired by the humpback whales flipper, is adopted to solve this problem. In this study, based on the NACA0015 airfoil, the three-dimensional unsteady numerical simulation and sliding mesh technique are used to reveal the flow control mechanism on the dynamic stall of the bionic wavy leading edge. The effects of the waviness ratio on the dynamic stall characteristics of the airfoil are also investigated. The results show that the peak drag coefficient is dramatically reduced when a sinusoidal leading edge is applied to the airfoil. Although the peak lift coefficient is also reduced, the reduction is much smaller. When the waviness ratio R is 0.8, the peak drag coefficient of the airfoil is reduced by 17.14% and the peak lift coefficient of the airfoil is reduced by 9.20%. The dynamic hysteresis effect is improved gradually with an increasing waviness ratio. For the bionic airfoil with R = 1.0, the area of the hysteresis loop is the smallest.

Experimental Study on the Structural Features and Corrosion Characteristics of Dolomite and Limestone in the Karst Stone Mountainous Areas in Northern Guangxi

Taking dolomite and limestone in Guilin and Liuzhou regions in the north of Guangxi Province as research objects, this paper analyzed their mineral composition and chemical composition, and then carried out the chemical corrosion test, the corrosion test under the chemical-temperature actions, and the corrosion test under the action of vibration load, respectively. The results showed that: (i) the dolomite in northern Guangxi mainly has fine crystalline texture and massive structure with low content of acid insoluble matters, while limestone mainly has powder crystalline texture and massive structure with high content of acid insoluble matters, and the purity of both dolomite and limestone are very high; (ii) the difference of corrosion between dolomite and limestone mainly depends on the ratio of CaO/MgO in their chemical composition, and the content of silica and acid insoluble matters; (iii) the corrosion rates of the pure dolomite and the pure limestone are basically the same under the same external conditions; (iv) temperature and vibration load have relatively large influence on the corrosion rates of dolomite and limestone, and the corrosion rates of dolomite and limestone increase with the increase of temperature, but the influence of vibration load on the corrosion rate is more significant than temperature. This research can provide theoretical basis and technical support for large-scale engineering construction and prevention of karst geologic disasters in karst stone mountainous areas in the northern Guangxi. Keywords: dolomite and limestone; structural features; corrosion characteristics; northern Guangxi

Industrial Monitoring Using Internet of Things -A MQTT Paradigm

Internet of things (IOT) has taken a very pervasive role in our technological advancement. Today we find development in medical, schools, industrial sectors using IOT to enhance their operations. IOT is used in medical to gather information about patient’s health records, in schools’ teachers are able to track attendance of students in the campus, in industries motor controls, maintenance, and predictive fault analysis are some of application. The architecture of IOT is setup in such a way that sensors and actuators are connected to the internet. The devices on which interface to internet are small embedded modules such as microcontroller which have limited resources and processing power at the edge. Hence an efficient and reliable communication protocol is needed which fulfills the design criteria. MQTT is implemented using client and broker network entities. In this paper a hardware system is developed which tracks and monitor the parameters like temperature, RPM, vibration, load current and voltage of induction motor. A Dashboard is developed which illustrates the various parameters on IOT cloud platform which can be accessed remotely. Keywords: MQTT-Message Queuing Telemetry Transport, edge computing, Industrial IOT.

Determiantion of energy characteristics of material destruction in the crushing chamber of the vibration crusher

The crushing equipment is characterized by a significant energy-consuming system during the crushing workflow. The current trend in the development of such processes puts forward requirements for the development of new or improvement of existing energy-saving equipment. The essence of the solution to the problem in this work is determined by using resonant modes, which are inherently the most effective. The practical implementation of the resonance mode has been achieved taking into account the conditions for the interaction of the resonant vibration crusher with the material at the stages of its destruction. The degree of the stress-strain state of the material is taken into account, which was a prerequisite for identifying the potential for the development of a vibration load. Composed equations of motion based on a substantiated discrete-continuous model of a vibration crusher and processing material. An approach is applied to determine the stepwise destruction of the material with the determination of the required degree of energy. This methodological approach made it possible to reveal the nature of the process of material destruction, where energy costs at the stages of crack formation, their development and final destruction are taken into account. It was revealed that the greatest energy consumption during the operation of crushers goes into the kinetic energy of the crushing plates and the potential energy of deformation of the springs. The proposed model is common for any design of a vibration machine and its operating modes. The stable resonance mode has made it possible to significantly reduce the energy consumption for the course of the technological process of material grinding. The results obtained are used to improve the calculation methods for vibratory jaw and cone crushers that implement the corresponding energy-saving stable zones of the working process.