Failure Of Elements Research Articles

ASSESSMENT OF THE PROBABILITY OF OCCURRENCE OF EMERGENCY SITUATIONS DURING OPERATION OF THE PYROLYSIS PLANT

The article discusses the issues of reliability and safety of operation of a pyrolysis plant for the disposal of used tires, which, in the context of an increasing volume of waste and the need for their effective disposal, is an urgent topic. The problem statement is related to the identification of factors affecting the reliability of the installation and the development of methods to prevent emergencies.The purpose of the study is to analyz the reliability of the pyrolysis plant and develop recommendations for its improvement. To achieve this goal, the causes and probabilities of failures of system elements are investigated, an analysis using the failure tree method is carried out. This method made it possible to identify the weaknesses of the system and assess the probability of their failures, which is critical to prevent emergencies.An assessment of the reliability of the installation showed that the greatest contribution to the probability of accidents is made by a malfunction of the gas separation system. This element is the most vulnerable due to its complexity and importance in the pyrolysis process, as it is responsible for the safe and effective separation of pyrolysis products. Any malfunction of the gas separation system can lead to the accumulation of dangerous gases, increasing the risk of explosions and fires. The identified emergencies require special attention to the development of effective measures to minimize them.The article proposes methods to improve the reliability of the system, the main of which is the redundancy of the most vulnerable elements. This will significantly reduce the probability of failures and increase the overall reliability of the installation. In addition, it is recommended to carry out regular inspections and maintenance of all elements of the system. These measures will help to identify and eliminate potential malfunctions in a timely manner, which will significantly reduce the likelihood of failures that can lead to emergencies.Thus, ensuring the reliability and safety of a pyrolysis plant for the disposal of used tires requires an integrated approach. Enabling redundancy of vulnerable elements and regular maintenance will minimize the likelihood of failures that can lead to emergencies and guarantee stable and safe operation of the system. These measures will not only increase the efficiency of disposal, but also ensure reliable and long-term operation of the installation.This article focuses on the importance of identifying vulnerable elements of the system and conducting regular maintenance to improve the reliability and safety of operation of the pyrolysis plant.

Risk Analysis of Level Crossing Element Failures in a Fuzzy Environment

The concept of risk analysis is especially important because it examines and analyses in a detailed manner the factors that affect the normal functioning of a system. In this paper, the level crossing is considered as one system, composed of several elements. The failures of those elements were analysed with the aim of showing which are the most frequent and most critical failures. A multi-methodological approach was used in the analysis. The failure modes and effects analysis (FMEA) method was used to determine risk factors, after that a multi-criteria model was created in a fuzzy environment, and as output, it gave a ranking list of critical failures in the system. Through the discussion of the results, a comparison of the basic model with two other similar ones was made, and the comparative results were analysed. The main aim of this paper is to present one of the possible ways to analyse the risk of the system of level crossings with the aim of improving traffic safety at the crossing.

Toward Limited Durability of Load-Bearing Beams of Metal Bridge Spans

The paper considers the limited durability as a structural property which continuously maintains operability during certain time under random loading of beam elements and proposes the definition for durability as the main criterion of failure and destruction of beam elements or beam as a whole.Methodology: Structural analysis; cumulative model of quasi-monotonic damage accumulation and failure of beam elements.Purpose: To develop methods to determine the durability based on damages representing a random, non-stationary loading process.Research findings: The damage accumulation is calculated for beams. The process is considered as quasi-monotonic. Stress-strain curves are obtained, including changes in probabilistic characteristics of not only structural materials, but also loading modes from the damage growth. The durability limitations of span girders are estimated both by nominal stresses and total damage in the more dangerous section.

Methodology for assessing the technical condition of electrical networks based on determining the probability of their failure

RELEVANCE. The current technical condition of electrical networks at the moment is generally unsatisfactory with an average level of physical wear of about 60-70 %, therefore,the development of fundamentally new methods for assessing their technical condition is currently an urgent task. The methods of assessing the technical condition of electrical networks analyzed in the article are based to a greater extent on the subjective and insufficiently accurate method of expert assessments, which actually does not take into account the data of its technical diagnostics, as well as statistics of defects and failures. OBJECT. To develop a methodology for assessing the technical condition of electrical networks, which would be based on probabilistic models characterizing the physical processes occurring in electrical networks, as well as data from their technical diagnostics, statistics of defects and failures. METHODS. To assess the technical condition of electrical networks, a probabilistic assessment method was used. In this case, the methodology involves sequential determination of the probabilities of occurrence of selected groups of emergency modes, the probability of failure of a network element as a whole, as well as the probability of failure of an object and a group of objects of the power grid. RESULTS. Based on the research results, probabilistic models of failure of electrical networks were obtained, which, unlike the assessment methods discussed in the article, are based on data from technical diagnostics and inspections of electrical equipment. An example of the implementation of the developed methodology on real electrical network objects is given. CONCLUSION. The developed methodology allows for a more reasonable prioritization of technical impacts on electrical grid equipment, which will make it possible to replace or repair equipment that has actually exhausted its physical resource, which will reduce the frequency of emergency conditions and reduce damage from power supply interruptions.

Fractographic investigation of carbon/epoxy PRSEUS composites exposed to flame after compressive failure

After a structural-related composite aircraft crash, a fractographic forensic analysis of the damaged surfaces is typically performed to assess the root causes of mechanical failures. Such accident reconstruction efforts, however, can be impeded if the aircraft catches on fire on the ground (i.e., a post-crash fire occurs), where flames or heat exposure can obscure or destroy the fracture surface morphologies of the fibers (i.e., the primary load carrying constituent). In this study, carbon/epoxy Pultruded Rod Stitched Efficient Unitized Structure (PRSEUS) skin-stringer assemblies were subjected to uniaxial compression and subsequently exposed to direct flame using a Bunsen burner. Specimens were oriented parallel, orthogonal, and at 45° to the flame axis for durations of 60 s. Additional vertical burn tests were performed for durations up to 300 s. Fractographic inspection of the failure surfaces before and after flame exposure was performed using a combination of destructive sectioning and scanning electron microscopy. The warp-knitted skin (fascia) surrounding the pultruded rod effectively served as a thermal protection layer, which shielded the rod’s broken filaments from significant thermal degradation and facilitated the identification of microbuckling and other mechanical failure mechanisms. This suggests that the presence of fascia, bulkheads, ribs, skins, and other intermediate layers in aircraft structures may significantly shield underlying principal structural element failure surfaces from fire exposure, facilitating post-crash forensic assessments of composite aircraft. Additionally, the through-thickness VectranTM stitching remained intact even after extended flame exposure, suggesting that such stitching can enhance the fire resistance of composite structures.

Классификация отказов и неисправностей легковых автомобилей с целью создания системы оценки технического состояния

The article provides an overview and classification of motor vehicle faults (class: passenger cars). The cause-and-effect relationships «Fault-RTA» are studied. Failure of steering and suspension elements entails loss of vehicle control, which leads to traffic accidents. It is determined that safety is significantly affected and cannot be self-diagnosed by articulated joints of ball joints and stabilizer struts. The ball joint is the support of the hub. Failure of the ball joint leads to loss of control of the vehicle’s trajectory due to the fact that the wheel occupies an arbitrary and uncontrolled position in the wheel arch. Wear of the ball joint consists in the occurrence of play in the joint, which is now diagnosed by human senses. The technical condition is assessed using a primitive method: the vehicle is suspended and, using a lever, the mechanic applies various loads to the ball joint. The article predicts the possibility of creating a self-diagnostic system for joints with articulated joints. Along with this, a statistical analysis of emerging failures and malfunctions in cars by brand and class is carried out, which allows us to assert the constancy of the problem under study. An analysis of the relationship between failures and malfunctions with road accidents is carried out, which reflects the most frequent causes of accidents due to vehicle malfunctions.

Theoretical model of ultimate shear capacity and flexural capacity design method of boundary elements for reinforced concrete frames with steel plate shear walls

AbstractThe steel plate shear walls (SPSWs) have been proven effective in reinforced concrete frames (RCFs) as a lateral force‐resistant structure. Despite of advancements, accurately predicting the ultimate shear capacity of RCFs with SPSWs remains challenging using current simplified models. Additionally, the flexural capacity design procedure for the boundary elements (beams and columns) in previous studies of RCF‐SPSWs involved intricate iterative procedures, hindering its widespread implementation. To address the two issues, this paper investigates the pushover responses and the plate‐frame interaction (PFI) of an RCF‐SPSWs system using theoretical and numerical methods. There are three main contributions. First, a theoretical model of ultimate shear capacity for RCF‐SPSWs is proposed, which can also be used to predict shear contributions of boundary frames in RCF‐SPSWs. Calculation errors for ultimate shear capacity of RCF‐SPSWs and shear contribution from the boundary frame are only 3.7% and 6.7% respectively, which are reduced dramatically compared with the traditional model. A simplified schematic diagram for the global collapse mechanism (uniform distribution of plastic hinges within a structure) of RCF‐SPSWs is developed to facilitate the calculation of internal work and reaction forces. Secondly, a flexural capacity design method for the boundary elements to avoid in‐span plastic hinges is proposed. The proposed method enables the achievement of direct estimation of the flexural demands that could trigger a global collapse mechanism, all without intricate iterative procedures. The applicability of current assumptions for the design of steel boundary frame in RCF‐SPSWs system is discussed, and engineering suggestions are provided to ensure safer and more economic designs. Comparison results confirmed the applicability of the proposed design method, which can be adopted to achieve the global collapse mechanism for RCF‐SPSW system. Thirdly, impacts of yielding panel actions on the flexural capacity of boundary elements of RCF‐SPSWs are clarified. Comparison results demonstrated that adding SPSWs to an RCF alters the axial force on boundary elements and significantly impacts the flexural capacity. A design suggestion is made to emphasize the importance of avoiding the balanced failure of boundary elements. The proposed theoretical model can be used to economize the cross‐section of boundary elements in RCF‐SPSWs system under seismic loads due to accurate prediction of their shear contribution; the proposed flexural capacity design method can achieve a global collapse mechanism, and thus the structural safety and energy dissipation capacity are improved; moreover, the building design efficiency is also improved due to avoidance of intricate iterative procedures.

Model and Methods of Traffic Routing in a Communication Network Using UAVs

Relevance. The development of 5G networks and subsequent generations is accompanied by the development of new services, in particular, virtual, augmented reality services, as well as telepresence, as well as radio access networks. In particular, there is an increase in operating frequencies, which poses additional challenges for organizing a network that can meet the requirements for the quality of traffic service from new services and ensure the availability of communication to users. These problems can be solved by various methods of placing access points, including using UAVs. This approach ensures the efficiency of construction and flexibility of the access network structure, but also requires the use of methods for placing access points in relation to users and other elements of the communication network. Problem statement: development of methods for placing routers in a UAV swarm and selecting traffic routes when organizing an access network, in order to improve the efficiency of the communication network. Purpose of the work: improving the efficiency of building an access network using UAVs through the development of clustering methods and distributing routers in a UAV swarm. Methods. The studies were carried out using the provisions of information theory, mathematical optimization methods, graph theory methods and clustering methods. The numerical results were obtained using the numerical simulation method in Python. Result. The developed model and methods allow for the distribution of network routers (access points) located on UAVs taking into account the quality of service and ensuring the construction of a connected mesh network and its connection with the mobile network, which can be used in both modern and future communication networks. Novelty: a modeling and methodological apparatus has been developed that allows for increasing the efficiency of building wireless access networks using UAVs, in particular, allowing for selecting the placement positions of routers in a UAV swarm and the logical structure of the network. The developed modeling and methodological apparatus solves the problem of traffic routing taking into account the quality of its service. Practical significance: the proposed model and methods can be used to organize service in 5G networks and subsequent generations. In particular, they allow for ensuring the availability of communication and the efficiency of network organization in cases of insufficient coverage, as well as in cases of failure of individual network elements. The ability to unload traffic to a local network allows for improving the quality of traffic service in the operator's network.

Mathematical and computer identification of the characteristics of oscillation frequency and deformations of the equipment element in the flush purification unit

The object of research is an element of equipment in a vibrating screen, which is an active working body in the form of a plate. The key element in the system of the flush purification unit is the vibrating screen. The basic design of the sieve does not allow the flush solution to be distributed evenly over the entire working surface. The concentration of drilling fluid in the central part of the equipment leads to premature abrasive wear and failure of the working element. Therefore, the structure of the vibrating screen needs to be improved in order to extend its service life. This task has been solved through the introduction of an active element to the structure for the redistribution of the solution through additional transverse vibrations. The use of such an active element is an important step for improving the quality and efficiency of the purification system, which could optimize production processes and reduce costs in industry. Taking into account transverse vibrations and calculating frequency parameters could help improve the design and use the vibrating screen more productively. An analysis of the frequencies of oscillations of the active element-plate for cleaning the flush liquid with a vibrating screen was performed and a comparison of the analytically obtained results with the simulation data using the finite element method in the COMSOL Multiphysics software was carried out. The results are the basis for designing vibrating screens, conducting experimental and industrial research, and testing the screens. Computer studies have confirmed the possibility of using the improved design of the vibrating screen. By comparing the results of the calculation and computer simulation, the error was determined to be within 5 %. The identified patterns could make it possible to select the plate oscillation frequencies depending on the known initial parameters, which would be useful for solving similar tasks.

A novel framework of building operation algorithm for the block of technical diagnostics of aircraft’s automatic control system

This article presents the problem of designing an automatic control system that is stable against errors and failures of sensors on aircraft. The sensor system has a technical diagnostic block that ensures diagnosis and eliminates typical errors and failures. Based on the determination of the error vector, damage can occur by adding measurement elements corresponding to the measurement parameters to the control system. When there are errors or failures of the sensor elements, the state vector of the system changes and is determined by measurements. The difference between the measured vector components when there are errors, failures and when working normally is the basis of the working algorithm of the failure diagnosis block. The results demonstrate encouraging prospects for practical implementations.

LOGICAL-PROBABLIC MODELING OF FAILURES OF GEODESIC NETWORKS

The credibility and reliability of the results of geodetic and cadastral works depends mainly on the accuracy of the instruments, the qualification of the observer, his professionalism and the reliability of the points of the geodetic network (GN). As a rule, in most cases, there is a well-founded choice of geodetic tools suitable for accuracy and the involvement of a highly qualified geodetic engineer to perform certain types of geodetic work. However, certain questions may arise regarding the determination of starting points for the creation of a reliable geodetic survey justification. The issue of selecting reliable geodetic points for performing engineering and geodetic works based on the application of reliability assessment methods is an urgent scientific problem today. The purpose of the work is to establish the optimal reliability assessment method based on the analysis of existing ones. Adapt this method to solve the problem of assessing the reliability of geodetic networks as one of the most important parameters characterizing its condition. Assess the reliability of the Dnipro geodetic network by constructing a fault tree. Calculate the dynamics of the intensity of GN failures during the 100-year period of its existence. Calculate the appropriate periodicity of surveys (monitoring) of GN depending on the intensity of failures of elements (geodetic points). Methodology. Analysis of international and national standards for reliability assessment, Standards of Ukraine, where the methods of system reliability assessment are given. Review of methods for assessing GN reliability. The deductive method with the construction of a geodetic network failure tree has been applied. This method is based on a logic-probabilistic model of cause-and-effect relationships of system failures with failures of its elements and other events. Scientific novelty. The optimal method of assessing the reliability of GN has been established. A GN failure tree has been built in the TopEvent FTA software tool. The reliability of the geodetic network has been evaluated, the intensity of failures at various stages of its operation has been calculated. Mathematical expressions of the failure functions of the geodetic network have been described by applying Boolean functions. Practical value. International and national regulatory documents and Standards of Ukraine of reliability assessment have been analyzed. In Standarts the methods of system reliability assessment have been given. The performed assessment of the reliability of the state of the geodetic network of the city of Dnipro helps to choose stable geodetic points for the creation of local geodetic networks and survey justification. Reasonable periodicity of monitoring for the survey of geodetic points has been substantiated. The use of reliable points of geodetic networks will allow obtaining reliable observation data, which will significantly increase the quality of engineering and geodetic works. Results. The functioning of the geodetic network of the city of Dnipro on the constructed sequential tree of failures has been considered. Boolean functions to describe the mathematical expressions of the failure functions of the geodetic network, which includes 5 and 10 elements have been used.

A 90-meter Split Hopkinson Tension–Torsion Bar: Design, Construction and First Tests

AbstractThis article describes the design, construction, and first experimental results of a 90 m-long Hopkinson bar which can perform high strain rate tests in a combined tension–torsion state. The system configuration is analogous to the classic Hopkinson bar technique, consisting of three bars: a pre-stressed bar, an input bar, and an output bar; the sample is placed between the input and output bar. The measurement is also based on the classical three-wave method, where the incident, transmitted and reflected waves are measured. Incident compression and torsional waves are simultaneously generated by the failure of a fragile element that connects the pre-stressed bar to electromechanical actuators; the indirect Hopkinson tension bar technique is exploited, where the compression wave reaches the end of the output bar without stressing the sample and is reflected as a tensile input wave. The length of the bars is designed so that the tensile wave reaches the sample from the output bar side at the same time as the torsion wave comes from the input bar. Void tests were carried out first, for preliminary analysis of the system behaviour. Then, successful tests have been conducted on samples made of AA7075 T6, both in combined and pure tension–torsion states; it has been possible to measure the tension–torsion stress–strain curves, from which the equivalent flow stress–strain curve has been evaluated and compared to the quasi-static ones.

Antenna Array Diagnosis in the Presence of Unknown Mutual Coupling using Optimization Technique

Antenna array diagnosis is an important operation in communication systems, whenever element (s) failure in the array that worsening the projected radiation pattern occur. There are various diagnostic techniques found in literature that employ compressive sensing. Conversely, the techniques are based on easy formulation of array factor with no incorporation of mutual coupling existing between the radiators. This article shows how this deficiency lead to defective and bad diagnosis when there is presence of mutual coupling using port-level coupling matrix and average embedded antenna pattern. Furthermore, the element excitations are optimized to reduce the effect of mutual coherence of system measurement matrix, causing reduced measurements required for effective fault detection. Numerical simulation and experimental results demonstrate how the incorporation of mutual coupling generates an adequate and reliable array diagnosis, which are not found in literature. For instance, when fault number is set at 5, and SNR equals 10 dB, the smallest measurements needed for the diagnosis, which is the most effective diagnosis, are achieved when the optimized excitations are used. In conclusion, the implementation of the developed framework using measurement probe in space, shows enough results towards the practical deployment for antenna systems in wireless communication system.

Algorithm for Assessing the Characteristics of a Waveguide Slot Antenna Array when Changing Antenna Element Phasing

Introduction. When operating antennas in various radio-electronic systems, the influence of phase shifter (PS) failures on the characteristics of phased array antennas, waveguide-slot phased array antennas (WSPAA) in particular, should be taken into account. A review of publications shows a lack of research studies into failures of these elements.Aim. Research of WSPAA characteristics in the event of PS failures, when their phase takes a value equal to zero instead of the required value.Materials and methods. Statistical modeling methods were used to study the impact of PS failures on WSPAA characteristics. Calculations were carried out using a PC and the Mathcad 15 applied mathematics package.Results. An algorithm for statistical modeling of the impact of PS failures on WSPAA characteristics is proposed. A relationship that connects the radiation pattern with the statistical sample volume and the number of failed PSs is presented. Malfunctions of emitters from 5 to 35 out of 50 elements were investigated. Changes in the following characteristics were obtained: standard deviation - from 0.064 to 0.18; relative values: radiation pattern width - from 8 to 18 %; level of side lobes - from 13 to 59 %; radiation power - from 0.9 to 0.3.Conclusion. The results obtained can be generalized and used in radio-electronic systems with antenna arrays at the stage of their development. Future work will address the influence of PS failures with phases being established randomly and with random values, as well as PS failures in which power does not pass into the emitter. Another important area concerns compensation of distortions resulting from failures of antenna elements.

Failure probability Forecasting for the warning and evacuation management system in case of fire

This article discusses the issue of fire safety insurance in educational institutions based on warning and fire evacuation control systems reliability modeling and forecasting. It was shown that these institutions are need of warning and evacuation management systems. To identify failures of individual elements of a complex technical system, failures were monitored during a selected period. When using the calculation method, the probability of trouble-free operation of the elements of the equipment system was identified. Based on the statistical data, schemes of the probability of failure-free operation of the warning and evacuation management systems were constructed and failure probabilities were determined. Ways to increase the level of trouble-free operation were identified. The requirements for security systems to maintain the required level were considered. They include compliance with the international fire safety standards, regular checks of systems operability, employees training to react to signals triggered by a fire alarm, and evacuation. The high efficiency of the methodology for determining the probabilities of trouble-free operation of the system at various stages of facility design and commissioning was emphasized. The contribution of the methodology to the general calculation of fire risks was shown.

Старение и надежность: как вариации во времени интенсивности отказов влияют на форму кривых дожития стареющих организмов

The article considers the regularities of the theory of reliability, which determine the constancy of the shape of the curves of organisms’ survival. The assumption that the probability of natural death is determined by the probability of accidental failure of a part of a series of homogeneous elements (cells) allows to obtain, analytically and through numerical experiments, survival curves similar to those observed in nature. The use of com-puter modelling methods makes it possible to identify the survival curve parameters determined by the dynamics of the probability of failure of an individual element. The value of one of these parameters, namely the coordinates of the inflection point of human survival curves, indicates that, apparently, both in long-lived species in general and in humans specifically, the ageing promoting mechanism is the progressive deterioration of reliability - the dilapidation of the elements (cells) crucial for ageing.

УПРАВЛЕНИЕ РЕЗЕРВАМИ ЗАПЧАСТЕЙ В МНОГОУРОВНЕВОЙ СТРУКТУРЕ ОБЕСПЕЧЕНИЯ НАДЕЖНОСТИ ТЕХНИЧЕСКИХ СИСТЕМ

The processes occurring in production systems are limited by agrotechnical requirements. The determining factor of the technological reliability of the system is the time of replacement of the failed element. The reliability of the system depends significantly on the ratio between the time of replacement of the failed element with a workable spare part and the allowable downtime in the operation of the production system. A set of spare parts and accessories should be considered as a kind of unloaded reserve. (Research purpose) The research purpose is formalizing the dependencies between the performance indicators of the spare parts supply system and optimizing the flow of applications for spare parts, taking into account their quality. (Materials and methods) It was noted that in order to assess the quality of spare parts and accessories on a certain date, it is advisable to fix three parts of the purchased batch of spare parts. The task of assessing the reliability of spare parts and accessories at an early stage of their use was formulated. (Results and discussion) It was found that for a batch of spare parts and accessories of poor quality, it is possible to make prompt decisions on complaints to the manufacturer of spare parts and their replacement. (Conclusions) It was stated that the processes of spending spare parts are stochastic. It was established that a set of spare parts and accessories is a kind of resource designed to improve the reliability of the functioning of technical systems. The availability factor of spare parts and accessories was proposed, taking into account the intensity of their failures during storage. The general reliability model should take into account: the strategy of replenishment of spare parts, the type of structure of the supply system, the type of failure model. Proved that the strategy of continuous replenishment of spare parts and accessories is effective. It provides, other things being equal, a higher value of the availability factor of spare parts and accessories.

NUMERICAL SIMULATIONS OF ELASTIC-PLASTIC CONTACT CONSIDERING FRICTION

The solution of the elastic-plastic contact is of major importance in contact mechanics because contact damage and wear are responsible for the failure of many machine elements subjected to contact load. In many situations including gears and bearings, the load is transmitted through a small contact region, i.e. a concentrated contact, and the resulting high gradients of stress often exceed the plastic yield limit of the softer material. Plastic flow is initiated at a certain depth, resulting in modification of contact geometry and of the stress state that can lead to crack inception and propagation. Understanding the contact behaviour in the presence of plastic strains is fundamental for predicting the contact resistance. Considering the mathematical model complexity for the contact between bodies of arbitrary boundary, as well as the dissipative nature of plasticity, an analytical solution for the elastic plastic contact problem is hard to accomplish. Alongside finite element analysis, semi-analytical methods are the only existing simulation tools for the elastic-plastic contact problems. This paper extends a previously reported elastic-plastic contact solver developed by the same author, by considering friction. In the previous solver iteration, residual displacements were calculated only in the normal contact direction, thus assuming that the shear displacements are small enough to be neglected, in other words, the contact was assumed frictionless. By considering friction, a slip-stick contact process is introduced, adding a new iterative loop in which the contact pressure and shear stresses are iterated until convergence is reached. The new computer simulation tool is expected to give more realistic predictions for the elastic-plastic contact between materials with dissimilar elastic properties, in which case the shear tractions disturb the stress and displacements fields calculated for the frictionless contact case. The results are expected to contribute to a better understanding of the contact processes in the presence of both plastic strains and friction.

Failure Analysis of a Suspended Inter-Array Power Cable between Two Spar-Type Floating Wind Turbines: Evaluating the Influence of Buoy Element Failure on the Cable

The suspended configuration of inter-array power cables between floating offshore wind turbines necessitates using various ancillary equipment, such as buoy elements and bend stiffeners, to maintain the desired cable geometry. The failure analysis is an important step in the design of an inter-array dynamic power cable layout. This study investigates the impact of buoy element failures on the structural integrity and fatigue life of inter-array power cable configurations in offshore environments, focusing on four environmental conditions representative of the North Sea. Utilizing numerical simulations and fatigue analysis in OrcaFlex, static and dynamic analyses are conducted to assess maximum tension, minimum bend radius (MBR), and fatigue life under single and two failure scenarios of buoy elements. The results indicate that single buoy failures significantly increase maximum tension at hang-off points. At the same time, MBR is found to be the smallest at the failure position, aiding in failure point identification. In addition, for the two buoy element failure scenarios, the maximum tension increase poses risks to structural integrity, while MBR and fatigue life have high sensitivity to the applied environmental conditions.

Method of constructive synthesis of a flat active phased array antenna with a limited number of active channels

A method of constructive synthesis of a flat active phased array antenna from linear horizontal sublattices with an unequal number of antenna elements and the number of active channels equal to the number of sublattices is proposed. The transmission coefficients of the active channels, the number of elements in the sublattices and the coordinates of the placement of the phase centers of the sublattices of the active phased array antenna array in a flat opening are considered as the desired parameters of the constructive synthesis problem. Restrictions are set on the shape of the boundary of the flat opening and the amplitude distribution in the opening of the active phased array antenna. The requirements for the scanning sector of the active phased array antenna are formulated. The method is based on an iterative procedure. In the process of its implementation, the deviation of the amplitude distribution in the opening of the active phased array antenna from the sublattices from the specified amplitude distribution is minimized. The method has shown its efficiency in the formation of various amplitude distributions in the AFAR opening. The stability of the problem solution to external influences, including in the event of failures of antenna elements, is estimated. The solutions obtained can be used in monopulse radar stations with mechanical beam scanning in the azimuthal plane and electronic scanning in the angular plane.