Wear Damage Research Articles

Effect of contact misalignment on fretting wear behavior between fuel cladding and Zr-4 grid

Cladding fuel rods supported in grids are important core components in pressurized water nuclear reactors. Small rod-to-grid misalignments can occur during the core manufacturing process. The presence of tilted contacts may promote fretting wear damage between claddings and grids by flow-induced vibrations (FIV). In this study, the influence of tilted contacts on the fretting wear between fuel rod cladding and a Zr-4 alloy grid, caused by deviations during assembly, was analyzed and discussed. A 3D finite element model was set up to obtain the stress state on the contact interface between the cladding and grid under different included angles. Results show that the wear morphology and profile presented evident dependence on the included angle. The change of the included angle between the cladding and grid changes the contact form of the two, leading to changes in the local stress and contact area in the interface. This process ultimately changes the thickness of the wear debris accumulation layer (WDL).

Research on the Effect of Pearlite Lamellar Spacing on Rolling Contact Wear Behavior of U75V Rail Steel

The damage mode of U75V rail steel in application is determined by its rolling wear behavior. In this paper, the pearlite microstructure of U75V steel is characterized to investigate the relationship between wear and fatigue behavior. The results show that, with decreasing of pearlite lamellar spacing, the wear resistance of the steel increases and the contact fatigue resistance decreases. The spacing decreasing causes the change of the wear mechanism from abrasive wear to adhesive wear, as well as the damage mode from wear damage to fatigue damage. The smaller the pearlite lamellar spacing is, the stronger the deformation of the cementite lamellar is. The thin cementite lamellar is hardly broken in the rolling friction to pile up a large number of dislocations in the ferrite matrix and the work hardening degree was improved. So, the plastic deformation layer is difficult to remove, and fatigue cracks are easy to initiate and extend to the interior of the material.

A Novel Carbide-Free Bainitic Heavy-Haul Wheel Steel with an Excellent Wear-Resistance under Rolling-Sliding Condition

With the rapid development of railways towards high speed and larger carrying capacity, the problem of wear and fatigue damage between wheel/rail is gradually becoming serious. However, traditional pearlite wheel/rail has reached the limit, which leads to more attention to developing a novel wheel/rail material. This study aims to report a novel carbide-free bainite wheel steel. The wear-resistance of novel steel was tested by a rolling-sliding wear experiment under heavy-haul condition and investigated the impacts of the running speeds on the damage mechanism of wear and fatigue. The results show that the yield strength of the bainite wheel was as high as 950 MPa and the hardness was 415 HV, which was superior to most of the reported typical wheel steel. During the process of wear, the surface damage of the wheel was mainly adhesive wear and fatigue damage, and the gradient strain layer (GS layer) was formed on the wheel surface. As the running speed increased, fatigue damage gradually became more serious than adhesive wear, and the shear stress and strain of the GS layer were enhanced. The higher thickness and hardening were produced on the GS layer, which is the main reason for the higher wear-resistance of the bainitic wheel under higher running speeds. In addition, the wear-resistance of the novel wheel steel was better than that of the reported wheel steel. This novel bainitic wheel is a promising wheel for heavy-haul condition applications, which could provide a guide in choosing bainitic wheel steel for the railway.

A ratcheting mechanism-based numerical model to predict damage initiation in twin-disc tests of premium rail steels

This work presents a ratcheting mechanism-based numerical model to study the initiation location and initiation life of rolling contact fatigue (RCF) or wear damage and the initial wear rate of premium rail steels under the laboratory twin-disc test conditions. Twin-disc tests are widely used in the studies of rail steels due to their ability to reproduce critical aspects of full-scale wheel-on-rail contact under controlled conditions and a relatively short test period compared to field tests. This study introduces a computational model to simulate the cyclic rolling contact for three premium rail steels (HE1, HE2, and LAHT) against wheel steel AAR Class-C under twin-disc test conditions. The cyclic rolling contact is achieved by repeatedly moving a non-Hertzian distribution of contact pressure and the calculated longitudinal surface traction upon a segment of the circumferential surface of the lower disc until a stabilized maximum ratcheting strain rate is reached. The RCF or wear damage initiation location is determined by the location showing the stabilized maximum ratcheting strain rate, and the damage initiation life is estimated by applying the ratcheting failure mechanism. Wear and RCF damages are distinguished by the depth of the damage initiation location. Wear damage is dominant when the location is near the surface. Otherwise, the damage will be RCF-dominated. The initial wear rate due to wear-dominated damage is estimated by identifying a critical profile and affected volume of worn material within the ratcheting strain rate field. The predicted initial wear rate is compared with the experimental result of the examined contact pair. This research can assist in a more profound understanding of the experiment results of a twin-disc test and provide a numerical basis for an experimental twin-disc test design. Furthermore, it may provide significant references for choosing rail steels.

Micromachining of predesigned perpendicular copper micropillar array by scanning electrochemical microscopy

Because the electrochemical reactions can occur gently at normal temperature and pressure, electrochemical micromachining (ECMM) is an important nontraditional precision machining technique free of tool wear, heating effect, residual stress, surface and subsurface damage, comparing with the ultra-precision milling, electrical discharging machining, laser beam machining, etc. Although scanning electrochemical microscopy (SECM) has been proven powerful in ECMM, it is difficult to fabricate the predesigned perpendicular microstructures because of the inhomogenous potential distribution, the complex electrode reaction kinetics and the interfacial mass transfer processes. Here we succeeded in fabricating the copper micropillar arrays by combining the SECM direct-writing mode and the ultrashort voltage pulse (USVP) modulations. The machining accuracy and efficiency are affected by multiple technical parameters, including the amplitude, the period and the duty cycle of the USVP modulations, the components and concentration of the electrolyte solution, the tip-substrate distance, the motion mode of the tool electrode, etc. By employing multiple parameters central composite experimental designs, we succeed in optimizing the technical parameters and avoiding the complexities of electrode processes. The results demonstrate the powerful capability of SECM in the controllable micromachining of the perpendicular metallic microstructures.

Spherical indentation of polycrystalline cubic boron nitride (PcBN): Contact damage evolution with increasing load and microstructural effects

The extremely severe conditions at which cutting tools are exposed in hard machining operations require tool materials with outstanding mechanical properties. Excellent combinations of high hardness and fracture toughness are aimed to enhance wear and contact damage resistance; and thus, reliability of the tool. Here, spherical indentation is used to induce controlled damage, under monotonic loads, and to assess the resulting damage scenario of polycrystalline cubic boron nitride (PcBN). In doing so, two grades with different content of cBN particles as well as chemical nature of the binder are investigated. Systematic and detailed inspection of residual imprints, by means of optical and scanning electron microscopy, is conducted to document critical loads for damage emergence and evolution through different stages, as a function of increasing load and microstructural assemblage. It is found that H-PcBN grade, with higher content of cBN particles and a metallic binder, exhibits higher resistance to crack nucleation as well as a more gradual transition between distinct damage scenarios. This enhanced response is linked to the concomitant increase of hardness and fracture toughness observed for that grade, as compared to the L-PcBN one, consisting of a significantly lower amount of superhard particles bound by a binder of ceramic nature. In-depth inspection of interaction between fissures and microstructure indicates the existence of four different crack paths for both PcBN grades - transgranular through cBN particles, across the binder phase, and intergranular along either cBN/cBN or cBN/binder interfaces. Relative frequency of these crack paths as well as operative toughening mechanisms define the effective crack growth resistance of each PcBN grade. In this regard, a higher fracture toughness is assessed for H-PcBN, as a result of crack bridging by metallic ductile ligaments together with the effective barrier-like role played by substructural features within cBN particles. Meanwhile, L-PcBN grade shows a rather low crack growth resistance, in direct correlation with the intrinsic brittle nature of the contiguous ceramic binder through which crack extension predominantly takes place. These relative differences in resistance to crack nucleation and growth become key for understanding the enhanced contact damage behaviour determined for the grade with higher content of cBN particles in this study.

Study on the evaluation and compensating strategy for the wear damage of non‐return valve during injection molding process

AbstractInjection molding (IM) is one of the most essential forming methods for plastics. However, some potential risks which influence part quality may occur in the molding process. A non‐return valve (NRV) is a major component on the screw head whose function is to seal during the injection process to prevent the backflow of the melt. The NRV will wear in this process and cause fluctuations in parameters and quality but the wear states of NRVs cannot be monitored without the disassembly of the injection barrel. In this study, we proposed an optimization method to compensate for the wear damage of the NRVs. The V/P switchover point in each molding cycle was recalculated and output to stabilize the part quality. As a result, the wear damage of the NRV on the current machine was able to be predicted and the part quality could be initially optimized in the condition that the NRV had a degree of wear. The experimental results reveal that our proposed compensation algorithm can monitor the type of wear of NRV online, and at the same time, it can compensate the axial wear of NRV and finally improve the consistency of product weight, which established a fundamental for further research in the future.

Comparative study on the impact-sliding wear behaviour of CAD/CAM resin-ceramic materials and tooth enamel.

To compare the impact-sliding wear of different CAD/CAM resin-ceramic materials and tooth enamel, and explore the corresponding wear damage mechanism. Human tooth enamel (EN), Vita ENAMIC (Vita, VE), Lava Ultimate (3M, LU), and GC CERASMART (GC, CS) were used in this study. The hardness, elastic modulus, and roughness values of the samples were measured. Further, impact-sliding wear tests were performed in a ball-on-flat configuration with spherical zirconia antagonists and the coefficients of friction (CoF) were recorded simultaneously. Additionally, a white light interferometer was used to determine the volume losses and scanning electron microscopy was used to observe the wear morphology of the wear scars and the damage feature in the vertical sections to clarify the damage mechanism during the impact-sliding wear test. EN exhibited the highest elastic modulus and CoF, followed by VE, LU, and CS. The hardness and roughness of EN and VE were similar and were higher than those of LU and CS. Throughout the wear tests, VE exhibited the highest volume loss, whereas CS exhibited the lowest. The wear damage characteristics of VE were similar to those of EN, displaying brittle fractures of inorganic substances and plastic deformation of organic substances in the impact part, exhibiting plough marks in the sliding parts. In the case of LU and CS, the entire wear areas displayed plastic deformation of the resin matrix, exfoliation of the filler particles, and plough marks. Enamel and polymer-infiltrated ceramic network materials exhibit similar wear damage modes. Additionally, the high-density nanocomposite resin material is the most resistant to impact-sliding wear from a tribological perspective.

Tire Quality Inspection System Based on Deep Learning

There have been many reports of accidents caused by the use of damaged and worn tires, and these accidents are more common on highways and during the rainy season. Although this is a common problem, many people cannot distinguish good tires from worn ones, increasing the risk of ending up with good tires on the road. A few years ago, the main technology for checking tire size was manual inspection. An important method is to determine the grade of the tread pattern bed by checking the depth and the shoulder pattern bed. Tires are one of the most important parts of a vehicle as they actively support driving. However, they often disagree when it comes to proper inspection and maintenance. Most of the time, the general public apparently does not care about their tires. Many will experience tooth wear and flank damage, and failure to follow up on these problems will cause long-term damage. However, this method is too expensive to use in a family car. This article presents a model used as a running image that can distinguish broken tires from rubbing tires. The model is based on the image displayed outside the user-supplied tire and determines its status after comparing it with the model data using the deep learning algorithm ResNet50. This model is made to remind you that it can be used in addition to equipment suitable for use in real life applications. With regulation by regulatory agencies, tire accidents can be reduced and damage to people and property on public roads can be prevented.

30 - In vitro sliding contact wear and subsurface damage of different direct resin composite used for additive rehabilitation

30 - In vitro sliding contact wear and subsurface damage of different direct resin composite used for additive rehabilitation

Mechanical safety of reinforced concrete structures at all stages of the life cycle

Ensuring the mechanical safety of operated buildings at all stages of the life cycle is an urgent task. This is especially important when planning major repairs and reconstruction in buildings, as well as determining the period of safe operation from the moment of the survey, i.e. clarification of the remaining service life. The total service life at the design stage is set by the customer and the general designer in accordance with the recommendations of GOST 27751-2014 «Reliability for constructions and foundations. General principles». Mechanical safety and durability are ensured when calculating structures using the limit state method, assigning protection measures depending on the operating conditions, as well as complying with the requirements of SP 255.1325800.2016 «Buildings and structures. Operating rules. General Provisions». A method for preliminary assessment of the mechanical safety of buildings and their structures is proposed for consideration, which eliminates some of the shortcomings of existing methods for calculating the residual life by physical wear (damage) of building structures based on the results of a visual inspection, the basis of which is the dependence of the allowable safe operation period on the percentage of reduced bearing capacity. It is proposed to use the results of a visual inspection performed in accordance with GOST 31937-2011 «Buildings and constructions. Rules of inspection and monitoring of the technical condition».

Exploring the effects of vibration on surface roughness during CNC face milling on aluminum 6061-T6 using sound chatter

Vibration is a dynamic instability of the cutting operation caused by the interaction of the machined tools varied with the process. Surface irregularity, tool wear damage, and higher cutting force are all caused by vibration in the cutting process. This article investigated the experimental effects of vibration on CNC face milling dependent on sound amplitude. Constant spindle speed, feed rate, and various cutting depths are the parameters that have been considered for the simulation experiment. The machine produced chatter while cutting to various depths based on the Mastercam X9 software program during the machining process. The sound chatter received has been analyzed in REW (Room EQ Wizard) which estimated the amplitude of the acoustic and surface finish. The average roughness (Ra) and average maximum peak (Rz) testing results reveal 2.19 µm and 14.73 µm, respectively. The spectrogram has shown a 21.5 dB SPL (Sound Pressure Level) with a continuous oscillation from 200 Hz to 20 kHz at a peak time of 589.01 ms, ranging from + 90% to −90% sound impulse. Eventually, the low sound amplitude consumed short waves and low vibration, which resulted in a good surface polish with high frequency.

Remarkable Wear Resistance in a Complex Concentrated Alloy with Nanohierarchical Architecture and Composition Undulation.

Sustained wear damages on the sliding surfaces of alloys are generally the culprit responsible for the failure of various mechanical systems. Inspired by high-entropy effects, here we deliberately deploy nanohierarchical architecture with composition undulation in a Ni50(AlNbTiV)50 complex concentrated alloy, which yields ultralow wear rate within the order of 10-7 to 10-6 mm3/Nm between room temperature and 800 °C. Such remarkable wear resistance heretofore represents one of the highest wear resistance reported for the bulk alloys or composites, and originates from the multi-type adaptive friction interface protection governed by intrinsically nano-coupled grains and nanoprecipitates. This cooperative heterostructure releases gradient frictional stress in stages upon wear at room temperature through the coexistence of multiple deformation pathways while activating a dense nanocrystalline glaze layer upon wear at 800 °C to minimize adhesive and oxidative wear. Our work uncovers a practical avenue for tailoring wear properties with multicomponent heterostructures over a wide temperature range.

Abrasive wear damages observation in engineering ceramics using micro-Raman tomography

Abrasive wear damages observation in engineering ceramics using micro-Raman tomography

Estudo da adesividade e do comportamento mecânico em misturas asfálticas com adição de cal hidratada e rejeito de mármore

Esta pesquisa teve por objetivo analisar os efeitos da cal hidratada e do rejeito de mármore nas propriedades mecânicas e adesividade das misturas asfálticas. Foi realizada a substituição de 1,5% no peso total do corpo de prova por cal e rejeito de mármore, comparando-os com uma mistura convencional. Foram executados os ensaios de resistência à tração por compressão diametral, módulo de resiliência, estabilidade e fluência, cântabro e dano por umidade. Os corpos de prova utilizados foram moldados conforme metodologia Marshall e distribuição granulométrica pertencente ao centro da faixa C do Departamento Nacional de Infraestrutura de Transportes. Os resultados mostraram que a utilização da cal e do rejeito de mármore melhoram consideravelmente a suscetibilidade ao dano e as propriedades mecânicas da mistura. Dessa forma, este trabalho corrobora com os efeitos benéficos da adição da cal em misturas asfáltica já descritos na bibliografia e identificou o potencial de uso do rejeito de mármore.

Friction anomaly alarm for bridge sliding bearings under operating environmental conditions

Bridge sliding bearings are critical elements to ensure the acceptable free expansion of bridges. Abnormal sliding friction implies peeling-off and wear damage of sliding bearings, which pose a threat to bridge safety. In this study, an alarm anomaly approach was developed for the sliding friction of bridge sliding bearings under operating environmental conditions. First, the common linear temperature-displacement relationship was briefly introduced, and a temperature-displacement hysteresis model that involves the sliding friction of sliding bearings was proposed. Then, a sliding friction index was extracted from the temperature-displacement hysteresis model, and the alarm approach for the sliding friction anomaly was constructed using the friction index with the cumulative sum control chart. Subsequently, the entire implementation procedure of the alarm anomaly approach for sliding friction was systematically described. Finally, an engineering application of the anomaly alarm approach was performed on a cable-stayed bridge with sliding bearings. The results indicate that the proposed temperature-displacement hysteresis model can straightforwardly reflect the sliding friction of the bearings, and the proposed anomaly alarm approach can effectively detect the mild increase in sliding friction of bridge bearings.

Correction: Studies on Fretting Wear Damage Assessment of Piecewise Linear Systems Having Predefined Gap

Correction: Studies on Fretting Wear Damage Assessment of Piecewise Linear Systems Having Predefined Gap

Studies on Fretting Wear Damage Assessment of Piecewise Linear Systems Having Predefined Gap

Studies on Fretting Wear Damage Assessment of Piecewise Linear Systems Having Predefined Gap

Gearbox fault diagnosis based on a fusion model of virtual physical model and data-driven method

Planetary gear system is widely used in wind power, construction machinery and helicopters, because of its large transmission ratio, strong load-bearing capacity and small size. Because the gears are usually in high-speed operation, their key components are subject to severe wear and impact damage. When the gearbox is subjected to a failure, it is often difficult to judge the operating status of the gearbox in real time. Since the gearbox system is complex, moreover, it is still difficult for the simulation model to accurately identify the gearbox fault. To address this issue, this paper proposes a digital twin-based signal fusion model to accurately identify gearbox faults at the signal level. The proposed model can identify minor faults occurring in planetary gearboxes by fusing actual and virtual signals. Firstly, on the basis of virtual prototype and the multibody dynamics software, a digital physical model based on Hertz theory and extended finite element method is proposed for gearbox dynamic monitoring and digital simulation, in which the gearbox can be visualized. Secondly, the data-driven method is used to extract and select features from real and simulation signals, and the fault of the planetary gearbox is detected by feature matching. Finally, the real and simulation signals are fused effectively based on variational mode decomposition and phase correction of generalized cross-correlation coefficient. The fault diagnosis result of the gearbox is finally determined by using the envelope spectrum of the fused signal. The experimental results show that the virtual real fusion method effectively improves the performance of the traditional signal diagnosis methods, and the fusion of the actual and virtual signals strengthens the fault features of the fused signals effectively.

Analysis of wear of a nitrided AISI H13 hot work tool steel in an aluminium hot extrusion process

The present work present experimental results of hot wear testing of AISI H13 tool steel with the aim of replicating the wear mechanisms occurring during hot extrusion process. The hot wear tests were carried out at a temperature of 550 °C and a sliding speed of 0.5 m/s for sliding distances of 1800, 3600 and 5400 m. A pin-on-disk test fixture was designed and fabricated to investigate the sliding between nitrided AISI H13 steel pins and 6063 aluminium alloy disks in a "flat surface-flat surface" conformal contact mode. The different characterisation techniques used (SEM/EDS, XRD) helped to better explain the complex wear mechanisms leading to surface degradation in the tribological couple. Graphitisation phenomenon caused by the dissolution of metastable iron carbide Fe3C was observed to occur after a sliding distance of 3600 m. In addition, coarsening, coalescence and tearing of carbides in the ultimate lower valleys of the degraded surface were observed to occur after 5400 m sliding distance. Nano-indentation technique was used to evaluate the cross-sectional hardness evolution of the nitrided layer, and results showed that the maximum value of hardness of 12.01 ± 0.63 GPa was obtained at the nearest point of the surface. Volume and surface parameters were used to characterise the surfaces before and after wear damage as function of sliding distance. The progressive variation and evolution of the peak material volume parameter (Vmp), core material volume (Vmc), core void volume (Vvc) and dale void volume (Vvv) parameters reached higher values after wear testing at 3600 m sliding distance indicating a synergy between different and complex wear mechanisms.