Main Types Of Damage Research Articles

Criteria of pressure and thermal damage during laser irradiation of port wine stains: Which is dominant to vascular lesions?

Port wine stains (PWSs) are congenital dermal vessel proliferations mainly treated with laser therapy. The complete removal of the vessel lesions is rarely achieved because of a lack of discriminatory analysis of the two competitive laser damages to blood vessels, namely, pressure damage and thermal damage. Unlike complete vessel constriction, which is caused by thermal damage that can be measured by temperature-related integral Ω, vessel rupture results from pressure damage, which has been seldom studied. In this study, the rupture potential index based on wall pressure (RPIP) was calculated as the ratio of locally acting pressure to the pressure threshold. RPIP > 1 and Ω > 103 were adopted as benchmarks to judge pressure damage (vessel rupture) and thermal damage (complete vessel constriction), respectively. A computational fluid dynamics simulation was carried out to provide the temperature and pressure field in the PWS vessel model during irradiation by 595 nm pulsed dye laser (PDL) or 1064 nm Nd:YAG laser. Numerical results showed that for the 595 nm laser, vessels constantly underwent rupture. The area of high RPIP determined the degree of rupture by predicting the large and multiple rupture locations of the vessel. By contrast, for the 1064 nm laser, complete constriction was the main damage type. To a single vessel of 100 μm diameter, the optimized laser parameters were E = 10 J/cm2 with tp = 6 ms for 595 nm PDL and E = 180 J/cm2 with tp = 6 ms 1064 nm for Nd:YAG laser.

Studying and designing improved coatings for labyrinth seals of gas­turbine engine turbines

An analysis of improving efficiency of aircraft engine turbines by means of improvement of composition of sealing coatings used in labyrinth seals was made. It was established that a number of contradictory requirements to properties of such coatings are imposed at the initial stage of engine running-in and during further operation. Main types of damage of above coatings used in the design of labyrinth seals during operation of gas turbine engines were shown. In connection with the necessity of raising temperature of gases in turbines of aircraft engines, it was proposed to additionally dope the serial nickel-based coatings with yttrium-containing master alloys. The results of study of influence of doping of the wearing-in sealing coatings on operating properties in conditions of action of a high-temperature gas flow were presented. It was found that doping of the KNA-82 serial coating with a multicomponent Co-Ni-Cr-Al-Y master alloy is the most rational solution.It was established that the use of the developed coating in a temperature range of 1,100...1,200 °C makes it possible to reduce specific consumption of fuel by aircraft engines by improving turbine efficiency and prevent wear of the end faces of ridges of the rotor labyrinth seal. Based on simulation of flow in the labyrinth seal clearance by numerical method, it was shown that the use of the developed coating materials in seals of the compressor turbine and the free turbine makes it possible to reduce amount of cooling air leakage into the turbine air-gas channel by reducing wear of tops of the labyrinth rotor seal ridge

Structural health monitoring of composite pressure vessels using guided ultrasonic waves

Composite pressure vessels are important components in the storage of gases under high pressure. Among others, a common type of pressure vessel is made of a metal liner overwrapped with a fibre-reinforced plastic material. Conventional hydrostatic tests, used to assess the integrity of pressure vessels, may overstress the material and thus reduce the remaining lifetime of the tested component. Therefore, a truly non-destructive structural health monitoring (SHM) system would not only ensure a safer usage and extended lifetime, but also remove the necessity for periodic inspection and the testing of pressure vessels. The authors propose the use of guided ultrasonic waves, which have the potential to detect the main damage types, such as cracking in the metal liner, fibre breaks and composite matrix delamination. For the design of such an SHM system, multimodal ultrasonic wave propagation and defect-mode interaction must be fully understood. In this paper, simulation results obtained by means of finite element modelling (FEM) are presented. Based on the findings, suggestions are made regarding appropriate wave modes and their interaction with different flaw types, as well as the necessary excitation and suitable sensor configurations. Finally, a first approach for a reliable SHM system for composite pressure vessels is suggested.

Advanced condition monitoring of Pelton turbines

The ability of hydropower to adapt the electricity generation to the demand is necessary to integrate wind and solar energy into the electrical grid. Nowadays, hydropower turbines are required to work under harsher operating conditions and an advanced condition monitoring to detect damage is crucial.In this paper the methodology to improve the condition monitoring of Pelton turbines is presented. First, the field data obtained from the vibration monitoring of 28 different Pelton turbines over 25 years has been studied. The main types of damage found were due to fatigue, cavitation and silt erosion. By analyzing the vibration signatures before and after maintenance tasks, the symptoms of damage detected from the measuring locations were determined for each case.Second, a theoretical model using numerical methods (FEM) was created in order to simulate the dynamic behavior of the turbine. The model was validated with the results obtained from on-site tests that were carried out in an existing turbine. The deformations and the stresses of the runner under different operating conditions could then be computed.The calibrated model was used to analyze in detail the effect of misalignment between nozzle and runner. In historic cases, this abnormal operating condition lead to severe damage in the turbine, due to the effect of fatigue in some locations of the buckets. The model reproduced well the symptoms detected in the field measurements. The stresses could be calculated, which eventually can be used to estimate the remaining useful life of the turbine.

Study on Influence of Diversified Parameters of Vehicle and Track on Wheel Hollow Wear

Wheel hollow wear of high‐speed train is one of the main damage types for the wheel. By optimizing the vehicle and track parameters and matching the wheel‐rail profile, the hollow wear of wheel can be reduced. In order to study the sensitivity of vehicle and track parameters to the wheel hollow wear, the sensitivity of suspension parameters and the track parameters of the CRH2Ctype high‐speed train wheel on the hollow wear of the wheel was studied by the parameter sensitivity analysis method. The concept of the cumulative wear power dissipation was put forward. The distribution characteristics of the wheel hollow wear under the different wheel/rail treads matching were forecasted. The results show that the damping of antihunting motion damper of the vehicle is the most sensitive to the maximum cumulative wear power dissipation of the wheel, followed by the longitudinal stiffness of tumbler journal box node, lateral stiffness of air‐spring suspension, vertical damping of primary suspension, vertical stiffness of track, and vertical damping of track. According to the analysis from the combination of sensitive parameters, the cumulative wear power dissipation is unevenly distributed in the lateral direction of the wheel tread and has the obvious peak area, which is basically the same as the actual wear distribution location in the field. The matching of the LMA wheel tread and the CN60N rail tread is a good choice to slow down the hollow wear and reduce the wheel wear rate. And the wheel reprofiling should be timely carried out, otherwise the wear rate would increase and the hollow wear would become more serious.

Material metabolism and lifecycle impact assessment towards sustainable resource management: A case study of the highway infrastructural system in Shandong Peninsula, China

The accelerated construction of general infrastructure with global urbanization necessitates the massive input of materials. The huge material input and waste output throughout the infrastructure's lifecycle have led to severe resource depletion and the accumulation of potential environmental risks. The systematic evaluation of typical infrastructure stocks is very important to study regional resource availability and explore sustainable development modes under intensive human activities. In this study, we build a material stock model for a highway system that is based on the theory of material metabolism. We analysed the scale and structures of the stock and its lifecycle effects in the Shandong Peninsula. The following results are shown: 1) the total material stock in the entire highway system was 1933.57 Mt in 2013, and the six materials with the largest inputs were stones, fly ash, lime, cement, mineral powder and asphalt, which together comprised 99.8% of the stocks; 2) the material-driven impacts mainly originated from production and construction stages, of which the main damage types were fossil fuels, inhalable inorganics, climate change and land use; 3) the end products for highway construction were mainly supplied by Shandong itself. The average transport distance for different materials ranged from 25 to 174 km. Steel, stone and asphalt had a longer transport distance than others; and 4) the top three parameters that largely affected the stocks were the road length, roadway structure, and cross-sectional subgrade structure. The inputs could be largely reduced by appropriately adjusting the structures of roadways and subgrades in low-class roads.

Анализ состояния производства и качества изготовления бронзо-баббитовых подшипников коленчатого вала тепловозных дизелей

The article gives the study on the areas of application of bronze-babbit bearings for diesel locomotives are considered. Information is provided on the types of diesel engines and locomotives for which they are installed, where such bearings are used. The main types of damage are described: fatigue and corrosion-cavitation wear and the factors affecting them. Authors presented results of research on technological factors that affect fatigue damage, such as the technology of tinning the bronze body with solders, the quality of pig babbit. The chemistry of calcium babbit and BK2 babbit in an antifriction layer is reviewed. The violations that occur during the manufacture of bearings by various manufacturers are described. The results of analysis of the influence of the chemical composition of babbit on its structure are presented. The influence of calcium and magnesium is described, in particular, on the formation of swelling on the babbit surface. The paper provides results of studies on the adaptability of the babbit layer to changes in friction conditions with the formation of various types of secondary structures. Micro-X-ray spectral studies of babbit layers of various liners and secondary structures on friction surfaces have been carried out. As the conclusion of the article the studies carried out and suggestions were made aimed at checking the quality of bronze-babbit bearings manufactured by various manufacturers.

Оценка эффективности применения антикоррозионного покрытия «Левикор» (Термишин) для деталей рельсовых скреплений

The main type of damage to the operating parts of railway equipment is corrosion-fatigue fracture. In the period 2013 - 2014 specialists of JSC VNIIZhT conduct an integrated comparative study of the effect of thermal diffusion coating Levikor on the physical-mechanical and operational characteristics of parts of rail fasteners (elastic clamps, clamp and embedded bolts, nuts). The aim of the test was to evaluate the effectiveness of the thermal diffusion zinc coating Levikor to protect against corrosion and extend the service life of parts of fasteners of the railway superstructure.Studies include laboratory and bench tests, static and cyclic tests of elastic clamps of rail fastenings ZhBR-65, clamp and embedded bolts and nuts after exposure to a corrosive environment in salt fog chamber and in operating terms. During the 13 months tested parts of the superstructure with the Levikor coating as part of KB65 fasteners were in operation in the Lysogorsky tunnel of the North-Caucasian railway, operating time was 30 million gross tons. Presented in the article comparative test results allow making the following conclusions:- KB65 fastening units with details with Levikor coating after being operated in Lysogorsky tunnel keep maintainability, whereas, in the absence of anti-corrosion coating fastening units are not repairable;- an increase was recorded in cyclic durability of clamps with anticorrosion coating Levikor under conditions of corrosive environment by 2.0 times and static strength by 1.4 times;- for areas with humid climate and increased atmospheric corrosion, expansion of the range of the upper parts of track superstructure, protected by coating Levikor is recommended as well as expansion of operational areas for its laying on the railway network of JSC Russian Railways.

El impacto del huracán Dean sobre la estructura y composición arbórea de un bosque manejado en Quintana roo, México

Los huracanes son considerados como uno de los factores más determinantes de la estructura y composición de muchos bosques tropicales. En Quintana Roo, estos fenómenos naturales son tan frecuentes que forman parte de la dinámica natural del bosque. El 21 de agosto de 2007, en el centrosur del Estado, ocurrió el huracán Dean, que afectó alrededor de 900,000 ha de la selva mediana subperennifolia. En este estudio se cuantifican los daños ocasionados sobre la vegetación y se analizan los cambios en la composición de especies y la estructura del bosque afectado por el huracán Dean. Se encontró que la composición del bosque no fue afectada significativamente y que el mayor efecto del huracán fue sobre la estructura del bosque. Los árboles más dañados fueron individuos de especies del sotobosque. Los principales tipos de daño fueron desramado, desenraizado y quebrado o ruptura del tronco. Asimismo, basados en fuentes bibliográficas y algunas observaciones durante el trabajo en campo, se discute el efecto que el aprovechamiento forestal puede tener en cuanto a incrementar la susceptibilidad de estos bosques al daño por viento. Se propone disminuir la cantidad de áreas de concentración de madera (bacadillas) durante la extracción forestal, así como incorporar a los planes de manejo forestal, el aprovechamiento de árboles dañados que ofrezcan alguna utilidad. También se propone el monitoreo a largo plazo de la dinámica de los bosques afectados en relación con los no afectados por huracanes.

Operational diagnostics of high voltage instrument current transformers

The research contains the results the analysis of oil-filled high-voltage current transformers and selected diagnostic parameters that enable to detect main types of damage. It is shown that in case of the most common faults numerous diagnostic parameters are to be controlled and it is not always possible in conditions of electric power systems modes control by operative dispatching staff of power systems. To reduce the information load on the personal, responsible for decision-making regarding modes control it is proposed to use the parameter of total residual resource, the method of this parameter determination is given, based on the usage of remaining resource ratios, defined by individual diagnostic parameters, taking into account statistical data, concerning taking the current transformers out of service. It is proposed to determine these factors in relative units, that will simplify their usage while determining the ratio of general residual resource that varies from 1 during putting into operation to 0, that corresponds to taking the transformer out of service. Application of mathematical tools of neural- fuzzy modeling, namely Sugeno algorithm, allows to develop mathematical and computer models of total residual resource that enables to determine the impact of diagnostic parameters on the ratio of total residual resource. In training sample of neural -fuzzy model it is suggested to use data, verified by independent experts and taken from the test reports. It is shown that the current prediction error residual life does not exceed 14%. It is expected that the error can be reduced by increasing the training set, and the number of failures in the current transformer will reduce the defects in the early stages of development

Role of nucleotide excision repair proteins in response to DNA damage induced by topoisomerase II inhibitors.

In cancer treatment, chemotherapy is one of the main strategies used. The knowledge of the cellular and molecular characteristics of tumors allows the use of more specific drugs, making the removal of tumors more efficient. Among the drugs of choice in these treatments, topoisomerase inhibitors are widely used against different types of tumors. Topoisomerases are enzymes responsible for maintaining the structure of DNA, altering its topological state temporarily during the processes of replication and transcription, in order to avoid supercoiling and entanglements at the double helix. The DNA damage formed as a result of topoisomerase inhibition can be repaired by DNA repair mechanisms. Thus, DNA repair pathways can modulate the effectiveness of chemotherapy. Homologous recombination (HR) and non-homologous end joining (NHEJ) are the main pathways involved in the removal of double strand breaks (DSBs); while nucleotide excision repair (NER) is mainly characterized by the removal of lesions that lead to significant structural distortions in the DNA double helix. Evidence has shown that DSBs are the main type of damage resulting from the inhibition of the DNA topoisomerase II enzyme, and therefore the involvement of HR and NHEJ pathways in the repair process is well established. However, some topoisomerase II inhibitors induce other types of lesions, like DNA adducts, interstrand crosslinks and reactive oxygen species, and studies have shown that other DNA repair pathways might be participating in removing injury induced by these drugs. This review aims to correlate the involvement of proteins from different DNA repair pathways in response to these drugs, with an emphasis on NER.

Information Security in Banking Conceptual Issues

The study clarifies the term and analyze the main directions and challenges for information security in the banking industry. Discussed are the main types of damage that banks incur as a result of compromise and incident information security.

A new type of anvil in the Acheulian of Gesher Benot Ya'aqov, Israel.

We report here on the identification and characterization of thin basalt anvils, a newly discovered component of the Acheulian lithic inventory of Gesher Benot Ya'aqov (GBY). These tools are an addition to the array of percussive tools (percussors, pitted stones and anvils) made of basalt, flint and limestone. The thin anvils were selected from particularly compact, horizontally fissured zones of basalt flows. This type of fissuring produces a natural geometry of thick and thin slabs. Hominins at GBY had multiple acquisition strategies, including the selection of thick slabs for the production of giant cores and cobbles for percussors. The selection of thin slabs was carried out according to yet another independent and targeted plan. The thinness of the anvils dictated a particular range of functions. The use of the anvils is well documented on their surfaces and edges. Two main types of damage are identified: those resulting from activities carried out on the surfaces of the anvils and those resulting from unintentional forceful blows (accidents de travaille). Percussive activities that may have been associated with the thin anvils include nut cracking and the processing of meat and bones, as well as plants.

Surface integrity of 2304 duplex stainless steel after different grinding operations

Surface integrity has significant effect on service performance of a component. In this study, the evolution of the surface and sub-surface changes induced by grinding duplex stainless steel (DSS) 2304 was studied with regard to the residual stress, the microstructure, surface roughness and surface defects. The results provide insights into the effect of abrasive grit size, grinding force and lubrication on the surface integrity. The abrasive grit size was found to have the largest influence. Surface defects, a highly deformed surface layer and the generation of tensile residual stresses along the grinding direction have been found to be the main types of damage induced by the grinding operation. Residual stresses induced by mechanical effects dominate over thermal effects in this study. The results obtained can be used to understand the contribution of surface condition and residual stress on failure of duplex stainless steels in service by fatigue or stress corrosion cracking.

Condition monitoring of pump-turbines. New challenges

At present, pumped storage is the only system to store huge amounts of energy. The surplus of energy in the electrical grid is used for pumping water from a lower to a higher reservoir (pump operation). At peak hours or in case of emergency this water goes down generating electrical energy (turbine operation). In the last years, due to the massive entrance of wind power, the number of start and stop cycles have increased dramatically as well as the operation at very low loads. In this new scenario more cases of damage have been reported and an effective vibration monitoring is necessary.Reversible pump-turbines (RPT) are high performance machines that have to change operation from pump to turbine mode (reversing runner rotation and flow direction) in a short time. Due to their special design characteristics (large power concentration) and operating conditions, they generate large pressure pulsations and forces when in operation.In this paper the vibration monitoring of large RPT units have been analysed. The results obtained after 15years of monitoring several power plants with this type of machines have been used for the analysis. In the last years, most of the supervised power plants have been monitored on-line remotely.First the monitoring system used is described. The main types of excitation forces expected during the operation of these machines are studied especially the most characteristic and distinctive that are the pressure pulsations due to the rotor/stator interaction.The vibration signatures measured in machines with different designs are analysed in detail and compared with the signatures of conventional turbines. The influence of the operation type (as a pump and or as a turbine) and on the power delivered has been studied and the changes of the signatures presented. After the analysis of the vibration signatures the procedure used for the selection of spectral bands is explained.The analysis of the results obtained with the monitoring is shown. First the evolution of overall levels and the comparison with vibration Standards is discussed. Second the main types of damage found are introduced. Damage in the generator, in bearings, in supporting structure and abnormal operation with cavitation are shown. The changes in vibration signatures and spectral bands for these types of damage are also given. Finally the specific case of damage in runners is introduced.

Post-operation state and extension of service life of compressor blades of the gas-turbine power plant GTE-45-3

Gas turbine engine compressor blades are the most essential parts among all the units of gas turbine power plants. They are made of chromium stainless steels. Erosive and corrosive wear of working surfaces as well as thermal stress fatigue are the main types of damage of compressor blades after long-term use. The aim of this work was to develop methods of recovering the serviceability of the material of the power plant ГТЭ-45-3 compressor blades with a view to extending their service life. To examine the post-operation state of compressor blades and the material serviceability the compressor blades of the gas turbine engine power plant ГТЭ-45-3 made of corrosion-resistant steels ЭИ961 (13Х11Н2В2МФ) and 12Х13 were investigated after their service life expired with the total engine hours equal to 50000. To evaluate the serviceability of the blade material an unconventional approach and know-how were used. The results of analysis of the microstructure of corrosion-resistant steels as well as their physical and mechanical properties are presented in the paper. A process of material serviceability recovery is developed with a view to extending the service life of compressor blades. The process includes the following sequence of operations: machining aimed at removing corrosion and mechanical defects, argon-arc welding that restores the geometry of the rotor blades, thermal tempering for removing residual stress.

Experimental Study on Flexural Behavior of Typical Mortise-Tenon Joints

The same two straight mortise-tennon joints in the base of melon-column (SJ for short) and penetrated mortise-tennon joints (PJ for short) were made with related rules. Relations of moment-rotation, length of the tenon pulled out-rotation and failure modes were got through monotonic loading test. Experimental study showed the main damage type of SJ was pulling out, while two damage types of PJ were bending damage and transverse tearing failure respectively. When under the action of bending moment, the resisting torque of SJ was synthesized by vertical load of columns, while that of PJ was mainly synthesized by local compresssive stress and friction on upper and lower surface of the tennon. In addition, the pulling size of tennons was associated with the heigth of tenon and relative rotation of beam and column.

Commonly Encountered Damages in Cable Members of CFST Arch Bridge and Detection Methods

A thorough research was made on the commonly encountered damages in cable members of the concrete filled steel tubular (CFST) arch bridge and their detection methods. Four main types of damages, including cable protection measure damage, anchor system damage, cable body damage and other damage types were discovered after a comprehensive study of the cable members on some existing CFST arch bridges and the related references. A focus has been placed to analysis each types of damages individually, based on their characteristics, failure mechanism and destructive effects. Furthermore, the detection methods for the damages in cable members were introduced and evaluated elaborately. Therefore, this study provides a valuable reference for the daily maintenance and maintenance specification establish for cable members of CFST arch bridge under different scenarios.

Study on the tribological properties of titanium alloys sliding against WC-Co during the dry friction

Purpose – Titanium alloy has the excellent performance and been widely utilized in aeroengine and airframe manufacture. However, improving the understanding of all aspects of titanium alloy is necessary. The purpose of this paper is to investigate the tribological properties of two typical titanium alloys against tungsten carbide under dry friction. Design/methodology/approach – Reciprocating ball-disc friction tests were carried out at room temperature in different loading without lubricant to investigate the friction properties of TA19/WC-Co and TC18/WC-Co friction pairs. The influence of the load on the friction coefficient and friction force was analyzed. The worn surfaces of TA19 and TC18 specimens were observed by the digital microscopy and scanning electron microscopy (SEM). And the wear mechanism was discussed. Findings – The results show that the friction coefficients decreased with the increase in the normal load. However, the reduction in the friction coefficient for the TC18 alloy was less than that for the TA19 alloy. The dynamic friction forces with time were not quite coincident with the variation trend of the friction coefficients during the sliding friction. The results observed by the SEM and EDS revealed that several grooving were the main type of frictional wear causing the surfaces of the TA19 and TC18 alloys. Originality/value – It is shown in the paper that the tribological property of TA19 alloy was better than that of TC18 when sliding against tungsten carbide under the dry friction conditions. The main types of damage to the TA19/WC-Co friction pair were the ploughing, the delamination fatigue associate with abrasive wear and some diffusive wear. The ploughing and abrasion were the main wear mechanisms for the surface of TC18 alloy.

5MW 풍력용 Pitch Drive 구성품의 부하에 관한 연구

Wind power is a type of clean energy source which does not produce carbon dioxide. The wind turbine industry is considered as a major growth industry in many countries. The main cause of wind turbine failure arises in the wind turbine gearbox, and the main type of damage occurs in the bearings and gears. Therefore, predictions of gear and bearing damage are very important to ensure the reliability of the wind turbine reducers used in these systems. In this research, in order to optimize the wind turbine reducer, a series of simulations and redesigns was done using the tool RomaxDesigner. The RomaxDesigner model was used to analyze the bearing life of the duty cycle for a 5 MW wind-turbine pitch drive and to calculate the load in operating states. The reducer was designed to satisfy the life requirement by analyzing bearing damage and calculating the stress values of the main parts of the reducer.