Main Damage Research Articles

Effects of short-time fasting and feeding frequencies within 24 hours on histology, cholecystokinin and trypsin enzyme activities of digestive organs in black bream, Megalobrama pellegrini (Tchang, 1930), juvenile

To study the regulation and feedback mechanism of cholecystokinin and trypsin in Black bream, Megalobrama pellegrini (Tchang, 1930) 60 days after hatching under 15 days short-term fasting and different feeding frequencies within 24 hours during the same period, Black bream (wet weight 183.75 ± 61.16 mg, total length 20.74 ± 4.08 mm) developed in a recirculating aquaculture system (RAS) were selected. In the short-term fasting trial, body weight, trypsin, and cholecystokinin (CCK) of the feeding control group (FCG) were higher than those of the fasting trial group (FTG). Trypsin and CCK in FTG reached the lowest value on day 9, and CCK content reached the highest value on day 11. In the 24-hour daily rhythm experiment, juvenile fish were randomly assigned to (A) once feeding, (B) twice feeding, (C) three times feeding, and (D) fasting. CCK showed a minimum at 1:00+ in group A, a peak at night in group B, and a maximum in group C, and a single satiety stimulus can lead to increased hunger. The four treatment groups had an apparent closed-loop regulation, while the control point of the fasting group (D) shifted forward to the next day. In this study, we found only negative feedback regulation of CCK and trypsin at the end of fasting, considering whether the secretory site or anti-inflammatory response caused the increase of CCK. The damage of epithelial cells in the villi of the foregut was greater than that in the hindgut and hepatopancreas, and the detachment of epithelial cells and the striatal margin was the main damage. Different feeding frequencies in a single day did not directly affect the long-term fluctuation of CCK and trypsin diurnal rhythm. Three meals per day may be more conducive to the long-term growth of juvenile Black bream. This study aimed to provide a reference for the feeding strategy of juvenile Black bream in the RAS.

Failure mechanisms of coarse-grained sandstone under pure mode I/II loading: insights from energy evolution and acoustic emission

ABSTRACT Tensile and shear failure are the main damage modes of rocks in geotechnical engineering. To investigate the energy evolution and failure characteristics of coarse-grained sandstone during pure mode I/II loading, loading-unloading tests were performed on cracked straight-through Brazilian discs (CSTBD) with different unloading levels (i), and its acoustic emission (AE) signals and microstructure were monitored. The results show that the AE signals of the CSTBD are negligible before the peak load (Mode I), or appear when the axial load exceeds a stress threshold and then increases significantly before the peak load (Mode II), and the Kaiser effect was observed in the second loading stage. The specimens’ input, elastic and dissipative energies varied quadratically with i. The elastic energy is always greater than the dissipative energy (Mode I), whereas the dissipative energy exceeds the elastic energy at i < 0.5 (Mode II). The crack propagation paths start from the crack tip and extend rapidly and straightly (Mode I) or slowly in the form of wing crack (Mode II) to the loading point. The microstructures of the specimens are mainly intergranular fracture (mode I) and transgranular fracture (mode II). The results provide references for studying energy evolution and failure mechanisms of rocks under mixed modes I+II/I+III loading.

A Pathological Diagnostic Method for Traditional Brick-Masonry Dwellings: A Case Study in Guangfu Ancient City

Many regions of the world have traditional dwellings, which not only represent the main form of residential architecture, but also carry the local vernacular culture, display the region’s unique architectural style, materials and technology, and have important historical and cultural value. Due to environmental factors, traditional dwellings often suffer from architectural damage that threatens the stability of their structure and affects their esthetics value, resulting in a significant number of abandoned and demolished houses. In order to scientifically and effectively solve the damage problems of traditional dwellings, based on the theory of architectural pathology, the following diagnostic method for damage manifestation and the characteristics of traditional houses is proposed: “Architectural Pathology Appraisal–Pathological Environment Analysis–Mechanical Properties Testings”. The traditional dwellings in the ancient city of Guangfu were used as a case study for the practical application of the methodology for analyzing the main types and causes of the damage of the dwellings by examining the damage information of the dwellings, collecting the environmental data of the damaged walls, and testing the mechanical properties of the damaged walls. The results show that the main damage type in the ancient city dwellings of Guangfu is dampness damage, with corrosion deterioration, wall alkali flooding, and the moisture infiltration phenomenon as the manifested symptoms, and the damage is mainly concentrated in the lower part of the wall. In addition, the humidity and moisture content in the lower part of the wall is higher than that in the upper part of the wall, and the compressive strength of the damaged part of the wall is lower than that of the undamaged part. The humid environment of the old town contributed significantly to the destruction of the dwellings, and water intrusion led to a reduction in the strength of the dwellings’ bricks. Through the diagnostic method of building pathology, the causes of Guangfu dwellings’ damage are identified, and scientific and targeted damage intervention suggestions are made. This is expected to provide guidance for the treatment and prevention of building pathology in the ancient city of Guangfu and serve as a reference for the diagnosis and treatment of pathology in traditional dwellings in other areas.

The current-carrying damage mechanism of gradient copper-based composite ceramics with different sliding speeds

Gradient design is one of the effective methods to solve the inhomogeneity of current-carrying damage. However, the current-carrying damage mechanism of gradient composites with different sliding speeds is not clear, which severely limits its popularization and application. The gradient Cu-graphite composites were fabricated through hot-pressing sintering, and the variation of current-carrying and mechanical properties of the composites at different speeds were investigated. The results indicated that the wear rate of the composites initially decreased, and then increased, while the current-carrying efficiency and current-carrying stability initially increased, and then decreased with an increase in speed. The composites exhibited better current carrying and mechanical properties at the speed of 1000 r/min. The wear rate of the composites was 0.75 × 10-4 mm3·N-1·m-1. Meanwhile, the current carrying efficiency and current carrying stability was 98.6% and 2.3%, respectively. Then, the main damage mechanism of the composites was plastic deformation.

Effect of warehouse storage on the alteration, cooking and organoleptic characteristics of Kponan yam (Dioscorea cayenensis-rotundata) of Côte d'Ivoire

Yam holds the top position in food crop production, and Kponan yam is highly prized by Ivorians. However, storage deterioration poses economic challenges for wholesalers and producers. This study assesses Kponan yam quality in warehouse storage, considering its geographical origin. To achieve this, yams from the Bondoukou, Bouna, and Kouassi-Kouassikro regions were kept at a warehouse in Abidjan, allowing an assessment of alterations, cooking properties, and organoleptic characteristics over a 3-month storage period. Kponan yam tubers were placed on boards at the warehouse's temperature (27.98 °C) and relative humidity (85.61 %). Temperature and humidity levels were recorded three times per week and four times daily at 08:00, 12:00, 16:00, and 20:00. Physical, cooking, and sensory characteristics were checked at harvest and during each month. The results showed that the main damage observed during storage at the warehouse was rotting and dehydration of the tubers. Rot rates were 47.53 % for yams grown in Bondoukou, 51.96 % for those grown in Bouna and 60.65 % for those grown in Kouassi-Kouassikro. Dehydrated tubers rates were 17.88 %, 25.04 % and 29.20 % for yams from Bondoukou, Bouna and Kouassi-Kouassikro, respectively. The browning indices of Kponan yams decrease (P < 0.05) during storage, with a much more marked effect for yams grown in Bouna (23.43-18.56) and Bondoukou (24.73-18.11), in contrast to those grown in Kouassi-Kouassikro (26.09–22.96). Hardness also dropped for Kponan yams grown in Bouna, Bondoukou and Kouassi-Kouassikro (38.94–25.19 N, 39.39–26.52 N and 35.59–26.66 N respectively). Sensory analysis showed that yams from Bouna stored for three months were rated highest in taste (score = 4). The storage quality of Kponan yams was influenced by the cultivation region. Organic production of Kponan yams benefits the environment and human health, while increasing shelf life.

Analysis of the features of the operating conditions of modern gas turbine blades and review of methods for determining their high-temperature strength parameters

The subject of the study is modern methods and materials for the manufacture of gas turbine blades, as well as approaches and methods for assessing their dynamic and static strength under high-temperature loading. The first purpose of the article is to describe the main methods of manufacturing turbine blades, provide examples of the materials used and the features of their crystal structure. The second purpose of the article is to review approaches to ensuring the dynamic and static strength parameters of single-crystal turbine blades, in particular, to avoid dangerous resonance modes, to study the parameters of anisotropic creep, high-temperature fatigue life, and long-term strength. The goal of the article is to highlight the main advantages and disadvantages of existing methods, approaches and techniques for assessing and ensuring high-temperature strength parameters of turbine blades under static and dynamic loading, in order to select the objectives of further research. Methods used to create the publication: methods of analysis and comparison, which were used to search and compare open literature sources of information in accordance with the purpose of the article, as well as the method of deduction, which was used to identify the main shortcomings of existing methods for assessing the high-temperature strength of gas turbine blades under static and dynamic loading to outline the goals of further research. The following results have been obtained. Literature sources related to the methods of manufacturing turbine blades, namely, directional crystallization and single-crystal casting, were analyzed. The advantages of single-crystal alloys for the manufacture of turbine blades, namely increased heat strength, heat resistance, fatigue strength, durability and crack resistance, are emphasized. The main modern methods for assessing the high-temperature strength of gas turbine blades with regard to the anisotropic characteristics of single-crystal alloys are analyzed and described. Conclusions. This publication presents information about gas turbine blades, in particular, provides meaningful information about the methods of their manufacture, as well as the materials used to produce them. The study analyses and identifies the main damaging effects on gas turbine blades during their operation. The material describes the achievements of scientists who have developed numerical and experimental methods for assessing the impact of the anisotropic characteristics of single-crystal nickel heat-resistant alloys on the fatigue strength, durability and creep of turbine blades.

Robustness of wavelet features for damage detection with neural network and digital twin

Recent studies demonstrate that the wavelet energy–based features are highly sensitive to local damages, and accurate damage identification could be achieved by integrating such features with neural networks. However, the robustness of the features in practical applications and the feasibility of generating damage information with a digital twin to facilitate training of neural networks have not been systematically investigated. This paper aims to provide new insight into the practicality of using wavelet energy–based features for accurate damage detection of structures. A systematic investigation into the tolerance of the normalised wavelet packet node energy features with neural network (NWPNE-NN) approach against measurement noises, excitations uncertainties and limited frequency range in the measured responses is carried out, with consideration of data fusion from multiple measurement points. The feasibility of a digital twin to simulate damage scenarios and generate training data for neural networks is explored, and the use of relative WPNE as a new feature is proposed. The results show that the NWPNE-NN approach is capable of detecting and quantifying the main damage in a structure. The neural networks trained by data generated from a well-calibrated digital twin is capable of identifying damage in the actual structure.

Investigation on the Machinability of Polycrystalline ZnS by Micro-Laser-Assisted Diamond Cutting.

Polycrystalline ZnS is a typical infrared optical material. It is widely used in advanced optical systems due to its excellent optical properties. The machining accuracy of polycrystalline ZnS optical elements must satisfy the requirements of high-performance system development. However, the soft and brittle nature of the material poses a challenge for high-quality and efficient machining. In recent years, in situ laser-assisted diamond cutting has been proven to be an effective method for ultra-precision cutting of brittle materials. In this study, the mechanism of in situ laser-assisted cutting on ultra-precision cutting machinability enhancement of ZnS was investigated. Firstly, the physical properties of ZnS were characterized by high-temperature nanoindentation experiments. The result revealed an increase in ductile machinability of ZnS due to plastic deformation and a decrease in microhardness and Young's modulus at high temperatures. It provided a fundamental theory for the ductile-brittle transition of ZnS. Subsequently, a series of diamond-cutting experiments were carried out to study the removal mechanism of ZnS during in situ laser-assisted cutting. It was found that the mass damage initiation depth groove generated by in situ laser-assisted cutting increased by 57.99% compared to the groove generated by ordinary cutting. It was found that micron-sized pits were suppressed under in situ laser-assisted cutting. The main damage form of HIP-ZnS was changed from flake spalling and pits to radial cleavage cracks. Additionally, the laser can suppress the removal mode difference of different grain crystallographic and ensure the ductile region processing. Finally, planning cutting experiments were carried out to verify that a smooth and uniform surface with Sa of 3.607 nm was achieved at a laser power of 20 W, which was 73.58% better than normal cutting. The main components of roughness were grain boundary steps and submicron pit. This study provides a promising method for ultra-precision cutting of ZnS.

Evaluation of wavelet decomposition level to enhance numerical analysis of seismic responses

In this study, the discrete wavelet transform (DWT) is used to enhance the efficiency of numerical analysis by decomposing earthquake excitation signals into low- and high-frequency components. The low-frequency components, considered as the main damaging factor in earthquake waves, stored in approximation coefficients have been used to perform time response analysis. In the selection of the ground motions, the special attention is given to the ratio of peak ground acceleration (PGA) to peak ground velocity (PGV). An ensemble of nine earthquake records have been selected and used. For each earthquake, displacement response spectra have been generated for both the original signal and its approximations at different DWT levels. To determine the most accurate decomposition level, the normalized root-mean-squared error (NRMSE) of wavelet energy has been computed in spectral displacement responses. The outcomes reveal a dependency of the decomposition level on the specific characteristics of each earthquake. Subsequently, structural analyses are conducted on base-isolated structures with varying story numbers, to examine the accuracy of decomposed signals. Employing both the original signal and its approximations to the structures, base mat displacements and roof accelerations are computed. The findings of the seismic analyses demonstrate the effectiveness of the proposed decomposition levels.

Bayesian Inference for the Calibration of Progressive Damage Model of Dovetail Specimens from Laminated Composite Fan Blade

Abstract Composite fan blades are the preferred alternative for the fan stage of most advanced high bypass ratio turbofan engines. The ability of the dovetail to safely bear this load is one of the key points of the multi-level “test pyramid” approach of compliance demonstration for special airworthiness regulation. Debonding between adjacent layers is the main damage mode of laminated composite fan blades. However, there is difficulty in measuring the as manufactured interlaminar mechanical properties used in finite element models. In this study, tensile loading was applied to simulate the interacting centrifugal force and capture mixed mode damage evolution. Structural responses and material damages were calibrated with measured tensile loads through Bayesian inversion. Posterior probability distributions of maximum interface tractions and contact stresses were solved using Markov chain Monte Carlo sampler. Results indicated the two bilinear cohesive material models had a capacity of predicting empirical means of longitudinal reaction forces as that in test considering additional discrepancy term (0.035 kN and 0.96 kN respectively), while they made an significant impact on the prediction of tensile load history especially when two delamination cracks initiated and propagated. Interface elements provided a higher matching quality in predicting loading history and capturing damage mechanism in association with in-plane progressive damage analysis. This calibrated parameter set could be functioned as benchmark in numerically determining the ultimate tensile load of dovetail elements and reducing the necessary number of physical tests at elemental length level.

Canonical and Non-Canonical Roles of Human DNA Polymerase η.

DNA damage tolerance pathways that allow for the completion of replication following fork arrest are critical in maintaining genome stability during cell division. The main DNA damage tolerance pathways include strand switching, replication fork reversal and translesion synthesis (TLS). The TLS pathway is mediated by specialised DNA polymerases that can accommodate altered DNA structures during DNA synthesis, and are important in allowing replication to proceed after fork arrest, preventing fork collapse that can generate more deleterious double-strand breaks in the genome. TLS may occur directly at the fork, or at gaps remaining behind the fork, in the process of post-replication repair. Inactivating mutations in the human POLH gene encoding the Y-family DNA polymerase Pol η causes the skin cancer-prone genetic disease xeroderma pigmentosum variant (XPV). Pol η also contributes to chemoresistance during cancer treatment by bypassing DNA lesions induced by anti-cancer drugs including cisplatin. We review the current understanding of the canonical role of Pol η in translesion synthesis following replication arrest, as well as a number of emerging non-canonical roles of the protein in other aspects of DNA metabolism.

Effect of Commercial Trap Design and Location on Captures of Diocalandra frumenti (Fabricius) (Coleoptera: Dryophthoridae) on Palm Trees.

Diocalandra frumenti (Fabricius) (Coleoptera: Dryophthoridae) is a weevil present in the Canary Islands, affecting economically important palms such as Phoenix canariensis H. Wildpret and its hybrids, for which there were no trapping tools. The larvae cause the main damage by burrowing galleries in the rachis of the leaves, causing premature drying and collapse. To develop an effective trap, six trials were carried out to evaluate the effect of trap type, design, colour, height, distance and location of the trap in relation to the palm tree on D. frumenti captures. This study confirms that the Econex® trap, green in colour, without a cover and with two ventilation holes of 2.5 cm in diameter, diametrically opposite each other and at 1 cm from the top of the base of the trap, baited with sugar cane and water, and placed between the first and second ring of green leaves of the palm canopy, is efficient in capturing D. frumenti. These results establish a basis for future research focused on the development of a specific trapping system based on semiochemicals to serve as a tool for detection, monitoring and mass trapping of D. frumenti.

Probabilistic Seismic Risk Assessment of Metro Tunnels in Soft Soils

Tunnels are of significant importance in the sustainable development of global urban areas, particularly in metropolitan areas. It is of the utmost importance to evaluate the seismic performance of tunnels across a wide spectrum of earthquake intensities. In order to address this, our study presents a framework for the assessment of seismic risk in tunnels. This study employs the city of Shanghai’s urban metro tunnels as case studies. The nominal values of seismic risk for the three main damage states—minor, moderate, and major—were calculated. Furthermore, the influence of utilizing disparate fragility functions on expected seismic risk assessments was investigated. In this framework, the probability density functions of the different fragility curve models are employed to treat the probability values associated with them as random variables. This approach aims to facilitate the propagation of IMV in seismic risk assessments. The results demonstrate that the Bayesian framework efficiently incorporates the full range of input model variability into risk estimation. The findings of this study offer a foundation for decision-making processes, seismic risk assessments, and the resilience management of urban infrastructure.

An investigation on the wear properties of the photocurable components produced by additive manufacturing for dentistry applications: Combined influences of UV exposure time, building direction, and sliding loads

AbstractAdditive manufacturing (AM) of polymers is a highly versatile technology that can be applied to many independent sectors like automotive, aviation, medicine, and dentistry. Since it has great potential for rapid prototyping, clean‐process concepts, and the ability to produce complex shapes, the layer‐by‐layer printing method is one of the most promising alternatives for future industrial production efforts. In that sense, different from the previous studies, this work aims to elucidate the friction and wear properties of the special dental samples manufactured via photopolymerization‐based AM technology according to both for printing parameters, and dry sliding test variables. Also, this is the first initiation to examine the combined influences of the UV exposure time, building direction, and sliding force on the surface roughness, hardness, friction coefficient, wear rate, and main plastic damage mechanism of the printed samples. The results showed that the maximum average hardness value was detected as 89.8 Shore D for vertically built samples printed with 8 s exposure time. In addition, vertically printed samples exhibited better wear resistance than the horizontal samples and the rising exposure time generally affected affirmatively the hardness levels of the samples. The lowest volume loss of 78 mm3 belonged to the vertical sample at 5 N. Further, increasing test force levels caused a decrease in the friction coefficient results and triggered the volume loss increase in the samples. Among all samples, the calculated friction coefficient values changed between 0.3 and 0.87. On the other side, scanning electron microscopy (SEM), and energy‐dispersive spectroscopy (EDS) analyses pointed out that ascending exposure times led to the altering contact surface matchings determining the final volume loss outcomes.Highlights To obtain better surface quality, vertical printing was a useful option. Horizontally printed samples exhibited higher friction coefficients. Curing time positively impacted the wear resistance for both orientations. Grooves and debris parts were observed on surfaces with low exposure times.

GTN poroplastic damage model construction and forming limit prediction of magnesium alloy based on BP-GA neural network

During plastic deformation processes, the ductile solids damage and fracture at the microscopic level originate from the evolution of micro -voids, including nucleation, growth and coalescence of voids. In this study, the fracture caused by damage of the AZ31 magnesium alloy sheet is analyzed using the Gurson-Tvergaard-Needleman (GTN) model. The damage parameters of the GTN model are determined by statistical void volume fractions (VVF) in three damage stages during uniaxial tensile experiments with scanning electron microscopy (SEM). The damage parameters are then optimized by the Back Propagation-Genetic Algorithms (BP-GA) neural network. According to the result, the main GTN damage parameters: the initial void volume, the critical volume fraction, the void volume fraction of the nucleation part, and the void volume fraction when the material finally fails are obtained, respectively. Comparing the simulation with the test, the results of the optimized parameters fit better. The void growth reflects the damage during the deformation process, and the GTN model can accurately predict the ductile damage. Furthermore, the experimental forming limit diagrams (FLDs) of the AZ31 sheet at 200℃ are accurately predicted using the parameters obtained by the GTN model. Good agreement has been observed between the experimental and predicted FLDs.

Probing fretting wear behavior of gauge-changeable spline axle under rotational bending loads

The latest generation of gauge-changeable trains in China feature designs with their wheels and axles connected by spline couples and cylindrical fits. In comparison to the interference fitted wheelset, the spline axle with clearance fit is more prone to fretting damage. In this study, the stress distribution of spline axle was analyzed using finite element method. Then, a rotatory bending test on scaled wheel/axle samples was conducted to reveal the fretting wear behavior of the gauge-changeable axle. During traction, the contact stress of the spline peaks at 311 MPa on the tooth’s root side, with a corresponding relative slip of 14 μm. Fretting wear is observed in the spline axle, the damage zone of the wheel seat can be categorized into five bands (A–E), and severely damaged areas are covered with red-brown debris. Moreover, the main damage mechanism of untreated spline axle and surface-modified spline axle is delamination accompanied with oxidation. The improved properties of plasma nitriding and grease lubricant are attributed to the high surface hardness and residual compressive stress, as well as low frictional stress.

Structural performance of precast concrete sandwich panels with bolt-steel plate connection subjected to axial loading

A new precast concrete sandwich panel with glass fiber-reinforced polymer connectors was proposed, utilizing bolt-steel plate connections. A compressive experiment was carried out to investigate the performance. The main damage was concrete crushing in the bolt connection region, at the panel bottom, and above the joint. The connector type, solid concrete rib, slenderness ratio, and thickness affected the failure mode and bearing capacity. The use of GFRP connectors and solid concrete ribs enhanced the ultimate bearing capacity and stiffness of the panels while reducing the lateral deflection. Higher slenderness ratios leading to reduced axial bearing capacity and increased lateral deflection. Finally, the results of the existing empirical calculation formulae were compared with experimental ones, and they were overly conservative. A new formula for predicting the bearing capacity was proposed, and the difference percentages between the proposed formula and experimental results were −0.4 %–2.8 %, which was the most accurate prediction formula.

Characterization of damage behavior and failure mechanisms of the bonded‐bolted hybrid three‐bolt joint in composite laminates

AbstractIn this paper, the mechanical properties, damage modes, and bolt load distribution of the bonded‐bolted hybrid three‐bolt joint were investigated by a combination of experiments and numerical simulations. Acoustic emission (AE) was used to monitor the tensile process of the connection in real time, and the K‐means clustering algorithm was used to realize the cluster analysis of the damage modes. A numerical simulation model of the tensile process of the joint was established using ABAQUS simulation software. The progressive damage evolution of composite laminates, and adhesive layer was characterized by using the VUMAT subroutine, the B‐K failure criterion, and cohesive element with zero thickness, respectively. The results show that four main damage modes occur in composite laminates during tension: matrix cracking, delamination, fiber pull‐out, and fiber breakage, with corresponding peak frequency ranges of (0–80 kHz), (80–210 kHz), (210–330 kHz), and (330–375 kHz), respectively. The adhesive layer between the laminates mainly exhibits peeling failure because of the secondary bending effect. In the load‐bearing process, the adhesive layer was loaded first and failed, and the bolt loading was delayed. Meanwhile, the results of bolt load distribution showed that the bolts and the adhesive layer at both ends carried greater loads.Highlights Damage modes and damage evolution of the bonded‐bolted hybrid joint in tension were analyzed by combining acoustic emission technology and numerical simulation. The simulation of delamination damage in composite laminates was carried out by inserting zero‐thickness cohesive elements into the laminates, and the delamination damage between the carbon fiber layup and the adjacent glass fiber layup was analyzed. The effect of the inclusion of the adhesive layer on the mechanical properties of the joint and the distribution of the bolt load was analyzed.

Study of the effect of void defects on the mechanical properties of fiber reinforced composites

This study is to investigate the mechanical properties of fiber-reinforced polymer (FRP) composites considering void defects by adopting a representative volume element model. The results reveal that initial damage always sprouts at the interface, the void defects affect the location of the initial damage and are the dominant factor in determining the stress required for damage sprouting. In addition, the void defects as well as the neighboring debonding interfaces together determine the direction of the main damage evolution zone. The transverse tensile properties are most affected by the void defects, while the longitudinal tensile properties are least affected. In particular, the strength is more sensitive to void defects than that of elastic constants. In addition, the mechanical properties of high Fiber Volume Fraction (FVF) FRP composites are significantly stronger affected by void defects than those of low FVF FRP composites.

The Analysis of Overflow Occurrences In Fuel Oil Purifiers At MV Dahlia Merah

A purifier is needed to maintain fuel quality and support ship engine performance. A purifier is a device that is a separator for oil from water and dirt based on its specific gravity. This research aims to determine the causes and impact of overflow on the fuel oil purifier. The data collection method used in this study is the observation method and discussion method with the crew or employees of PT. Kayu Lapis Indonesia as the ship owner, and literature study methods. This research uses a qualitative analysis method, namely by directly analyzing the problems in the fuel oil purifier. The research results concluded that the cause of overflow in the fuel oil purifier was due to a dirty bowl caused by a lack of cleaning and maintenance of the Main Cylinder, damage or wear to the Main Seal Ring and a dead end of the nozzle. The efforts made to overcome overflow in the fuel oil purifier are by blowing up manually, carrying out cleaning (overhaul) of the purifier bowl and walls, checking the fuel pressure entering the FO purifier, setting the temperature on the fuel heater, installing Play the Seal Ring correctly, maintain the nozzle and maintain the HFO purifier by the PMS &amp; Instruction manual book.