Life Of Components Research Articles

The RUL prediction based on improved Wiener degradation model for wet friction components

The wet clutch is a critical component of the comprehensive transmission system, and its reliability determines the stability of heavy equipment operation. As the core component of the wet clutch, the life of the wet friction components directly affects the reliability of the wet clutch. To accurately predict the wet friction components remaining useful life (RUL), an improved Wiener degradation model is established. Compared to traditional models, it sets drift parameters as random parameters to consider the randomness of degradation process. The life and degradation data of wet friction components are obtained through accelerated life test, and the composite degradation indicator is constructed by screening and fusing degradation data. Innovatively, we fuse life and degradation data to reduce early errors in RUL prediction of wet friction components. The result shows that the RUL prediction average absolute error of the improved Wiener degradation model is 0.31 h in the accelerated life range of 80 h–110 h, which verifies the accuracy of the model.

Equivalent characterization of initial crack size of blunt notched components based on test data and physical model

The precise definition of initial crack size applicable to fracture mechanics is crucial for predicting the total fatigue life of structural components. Given that the demarcation between crack formation and crack propagation depends not only on the material but also on the stress level, theoretical and experimental procedures for defining the crack boundary point are developed. Underlying the procedure is that the designed notched members have the same local stress distribution as the structure. Consequently, the fatigue life and initial crack size of S355J2 steel notched components with different scales but similar stress fields were predicted and compared with experimental data. Results show that fatigue life predictions fall within ±2 factor band, and the crack initiation size obtained by AM is closest to the experimental results, with a difference of less than 30.2%, which proves that the approach of treating the initial crack size as a function related to fatigue life and fatigue notch factor is reasonable.

Renewable energy trading: Assessment by blockchain

Renewable energy trading could be considered the next step in power trading's development. It is probable that individuals currently involved in power trading will need to upgrade their data collection, processing, and reporting systems. This article provides a comprehensive evaluation of renewable energy trading utilizing Blockchain technology. Initially, the paper examines country-specific renewable energy trading with a focus on India, China, the US, France, and Germany's renewable energy policies. Moreover, the paper presents potential renewable energy trading markets such as peer-to-peer, over the grid, and partially or fully independent microgrid's. This paper shows the appraisal of bond, commodity, derivative, and algorithm-based renewable energy trading using different Blockchain methods, including Ethereum and R3 Corda. It is find out during the renewable energy trading, proposers of bid, also include capital cost of the renewable energy power plant, salvage value after useful life of different component of renewable energy power plant. It is also find out proper trading is to be done with offering subsidies of up to 70 % of the capital cost, and with a 30 % viability gap finance (VGF) at this cost.

A promising approach to enhance fatigue life of TC11 titanium alloy: Low dislocation density and surface grain refinement induced by electropulsing

The fatigue life of components can be significantly enhanced by the formation of the surface hardness layer through surface strengthening technology. To avoid the geometric distortion of thin-walled components caused by strengthening, the strengthening energy is limited and the ideal strengthening effect cannot be obtained. This work aims to propose a novel approach to address this issue effectively. The surface layer with high-density dislocations was obtained by a low-energy surface strengthening method (shot peening) at first. Then the surface strengthening mechanism changes from dislocation strengthening to grain boundary strengthening after electropulsing treatment (EPT). The evolution of residual stress and microstructure was analyzed using multi-scale characterization techniques. The results demonstrate that EPT followed by surface strengthening makes a remarkable 304 % increase in fatigue life of TC11 titanium alloy. The enhancement of fatigue life can be attributed to the grain refinement accompanied by the formation of nanotwins and sub-grains in the surface-strengthened layer, as well as the reduction in dislocation density within the substrate after EPT. This study demonstrates the significant potential of EPT in further enhancing the fatigue life of surface pre-strengthened thin-walled components.

Fatigue crack growth simulation by extended finite element method: A review of case studies

AbstractNumerical simulation of fatigue crack growth (FCG) is presented, based on the application of the extended finite element method (XFEM). Couple of case studies are presented, as a review of recent experience of the Belgrade school of XFEM simulations, established at the Faculty of Mechanical Engineering. Case studies comprised Charpy specimen with initial crack at the notch tip, oil rig pipe with an axial surface crack, pressure vessels with a crack at the welded joint with connecting pipe, turbine shaft with a crack at the transition radius, optimization of a wing spar in respect to FCG, the effect of mesh size on fatigue life estimation of a stringer panel, fatigue life estimation of wing‐to‐fuselage connecting lug, geometry effect on fatigue life of orthopedic plates and fatigue life of hip implant. Based on these case studies, XFEM is discussed in respect to its accuracy and efficiency. It is concluded that XFEM is a versatile tool for simulation of FCG, providing an excellent option for precise and reliable fatigue life of a cracked component.

The oxidation life analysis method for SiC/SiC composite components based on an equivalent diffusion coefficient model

AbstractA method for the oxidation life analysis of SiC/SiC composite structures was proposed to predict the oxidation life of ceramic matrix composite (CMC) components. In this paper, multiscale diffusion–oxidation simulation of the CMCs’ structure can be carried out by establishing the equivalent diffusion coefficient model, to get the microscopic oxidation morphology parameters at each point. Based on the results, the residual stiffness is calculated with the homogenization method. Then, the residual stiffness is taken as the material parameter of element to calculate the stress distribution after oxidation in the CMC structure. And the residual strength of CMCs was calculated by progressive damage analysis. The oxidation life of CMC component is analyzed by judging the failure condition of each element. Finally, the oxidation life prediction of the CMC adjustment sheet under specific loading environment is realized, which is about 1 200 h. The results show that this method is feasible for the calculation of hot end parts under actual complex loads.

An innovative approach to planar mixed-mode fatigue crack growth study

Determining fatigue crack growth parameters under mixed-mode loading is crucial for damage tolerance design, particularly in assessing a component's residual life with defects to prevent disasters. This study introduces a novel methodology for determining fatigue crack growth rate. A digital microscope is utilized to track the fatigue crack tip with respect to local coordinate systems established on the specimen surface. A grid is drawn and subdivided into units with proposed nomenclature. Compact Tension and Shear (CTS) specimens, extracted from AA-7085 plates, undergo fatigue loading in a servo-hydraulic universal testing machine. A fixture proposed by Richard et al. induces planar mixed-mode loading cases in the specimen. During experiments, the digital microscope tracks the crack tip using grid unit corners as local origins. The local coordinates of the crack tip are transformed into the crack tip coordinates with respect to the pre-crack tip. Crack evolution data are used to determine the fatigue crack growth rate by analyzing tangents of a three-parameter fitted curve. The equivalent SIF ranges are computed at different crack lengths in an XFEM script written in Ansys. The modified Paris parameters are found and experimentally observed crack deflection angles are compared with the Maximum Tangential stress, Strain energy density, and Richard’s criterion.

Microtexture region segmentation of eddy current testing data using a structural prior

Microtexture regions (MTRs) are collections of grains with similar crystallographic orientation. Because their presence in titanium alloys can significantly impact aerospace component life, a nondestructive method to detect and characterize MTR is needed. In this work, we propose to use data from two nondestructive evaluation methods, eddy current testing (ECT) and scanning acoustic microscopy (SAM), in order to recover the boundary and dominant crystallographic orientation of each MTR in a specimen. ECT is an electromagnetic method that is sensitive to changes in crystallographic orientation associated with MTR; however, its low resolution prevents it from resolving MTR boundaries well. In contrast, SAM is a high frequency ultrasound method that is able to resolve MTR boundaries but is not sensitive to orientation. This paper proposes an algorithm to characterize MTR that makes use of a method known as covariance generalized matching component analysis. This method is used to build a surrogate linear forward model that relates MTR boundaries and orientation to ECT data. The model is inverted using the SAM data as a structural prior. We demonstrate this technique using simulated ECT and experimental SAM data from a large grain titanium specimen.

Integrity Ratio: A Damage Mitigation Control Metric for Component Life Extension

Component life extension using control schemes involves a trade-off between vehicle maneuver performance and maneuver’s impact on component life usage. In many cases, effective schemes are predicated on the availability of effective metrics in their evaluations. In this paper, a new metric, called the integrity ratio, is introduced to improve existing control schemes and guide the development of future ones. It contains information pertaining to component damage growth and maneuver performance and is evaluated using a surrogate model for damage prediction and a harmonic load limiting control scheme. Important findings indicate that limiting harmonic load with a higher integrity ratio helps to reduce damage growth while preserving vehicle maneuverability. A demonstration showcased that a reduction of 10% in damage growth can be achieved with less than a 1% change in maneuver. The utilization of the integrity ratio metric enables a holistic and less conservative damage-driven control strategy for extending the operational life of a component, compared to traditional methods such as load alleviation and load limiting.

Creep strain prediction in power plant material via ANN modelling of nonlinear ultrasonic test results

ABSTRACT Reliable and accurate prediction of the creep life of power plant components is crucial for both economic and safety reasons. Existing prediction models, based on creep test data, can be complex and time-consuming. Nonlinear ultrasonic (NLU) is a widely-accepted non-destructive testing (NDT) technique for evaluating damage progression in crept specimens. The information from NLU measurements alone is insufficient to forecast the life of any component. In real-time applications, intelligent NDT protocols are needed to enable fast and accurate life prediction of such components. A methodology for creep life prediction using artificial neural networks (ANN) has been introduced based on NLU test results of crept P92 steel specimens. The technique involved creep tests of P92 specimens exposed to a temperature of 625⁰C with applied stress ranging from 120MPa to 160MPa, NLU measurements at each step load, and prediction of creep life of the material with a ANN trained with creep strain and NLU test data. The technique involves prediction from previously generated historical data, thus saving both cost and time of conducting continuous experiments. This approach for ANN modeling of NLU data can be considered a reliable, time-saving, and effective technique for assessing creep damage progression in power plant components.

Frictional vibration analysis of train braking system considering wheel-rail attachment and multi-body friction

Train vibration and noise have always been problems that affect the service life of relevant components and passenger comfort. This paper focuses on the vibration of the train braking system and establishes a torsional vibration model of the train braking system considering wheel-rail attachment and multi-body friction, which includes three rotational degrees of freedom of the brake disc, brake block, and wheelset. The periodic vibration and chaotic bifurcation of the braking system under low-speed working conditions are studied by numerical calculation. An optimization strategy is proposed for the chaotic bifurcation behavior, which eliminates the chaotic interval at low speeds through the reasonable matching of particle parameters, so as to ameliorate the brake groan problem of the train.

An intelligent schedule maintenance method for hydrogen fuel cell vehicles based on deep reinforcement learning considering dynamic reliability

Schedule maintenance activities for hydrogen fuel cell vehicles are aimed to keep them in better condition in long-term operation. In this paper, we develop a reinforcement learning based schedule maintenance strategy, which is used to comprehensively consider the balance between safety and maintenance cost, so as to find the optimal maintenance strategy. A multi-level framework is established with remaining useful life of key components, fault tree analysis, and logistics cost model to generate an exploration environment that can express the operational stability, the failure rate of components, and the cost of repair and storage. The trained agent combines a deep neural network to explore the optimal strategy under the dynamic reliability of key components. Finite steps are the constraints. Safety rates, maintenance cost, and episode of operation are incorporated into a multi-objective reward function. The hydrogen supply circuit of fuel cell vehicle is simulated via Python. The trained agent is compared with traditional time-based schedule maintenance strategy and corrective maintenance strategy. The results show that the reinforcement learning based schedule maintenance agent has optimized the total reward, cost control and accident rate by 77%, 59% and 5%, respectively, compared with the traditional time-based schedule maintenance strategy. In the safe operation management of fuel cell vehicles, efficient and stable decision-making ability has been achieved.

Augmenting materials passports to support disassembly planning based on building information modelling standards

Selective disassembly planning and materials passports are precursor technologies to support the retrieval of reusable building components efficiently. Selective disassembly relies on information about the recovery capacity of the components, while materials passports can be used to keep track of the disassembly information along the component's life cycles. However, the required information for selective disassembly is not represented in materials passports. Therefore, we developed a research approach to augment materials passports by integrating the information related to the components recovery capacity using a BIM-based Semantic Enrichment Engine for Disassembly Planning (SEEDP). First, we investigated the required information for selective disassembly and we proposed a characterization schema for disassembly models. Then, we developed the semantic enriching engine, SEEDP, as a comprehensive solution to automate three crucial steps: data pre-processing, production of materials passports for components, and assessment of disassembly models. Finally, we implemented the approach for two case studies as a functional demonstration.

Contemporary Intensive Methods of Steel Hardening in Cold Fluids

In the paper, the new intensive quenching technologies are discussed which are based on controlling the self-regulated thermal process (SRTP) which exists for a long time if any film boiling is absent. It is rather intensive until convection starts. Despite the intense process (Kn > 0.8), when the heat transfer coefficient and Biot number tend to infinity, there are several ways of controlling the surface temperature of steel components by varying the boiling temperature of the fluid. To eliminate any film boiling process and provide SRTP, the author of the paper explores the resonance effect, a thin surface insulating layer that covers the surface of machine components and electrical negative forces to control the double electrical layer that is responsible for destroying the film boiling mode. Based on SRTP control it is possible to delay the transformation austenite into martensite or even accelerate these transformations. The most important are possibilities to control surface temperature during the boiling process. All of this opens great opportunities for increasing significantly service life of machine components and tools. In the paper also the simplified method of cooling time calculation is proposed. It is based on the new principles concerning pure transient nucleate boiling taking place during the hardening steel in cold fluids. Since the paper simply explains everything, results of investigations will be widely used in the heat-treating industry.

Influence of contour processing parameters on porosity, surface roughness, and fatigue life in laser powder bed Al-10Si-0.4Mg

Additive manufacturing (AM) enables fabrication of net-shape components with high geometric complexity, however mechanical properties of parts with as-fabricated surfaces are limited by surface roughness and subsurface porosity that may initiate fatigue cracks. This study aims to improve the utility of parts with as-fabricated surfaces by quantifying processing-surface condition-fatigue performance relationships, optimizing surface contour parameters for fatigue performance, and investigating the application of surface profilometry as a non-destructive quality control method. Eleven contour parameter sets of varying energy densities were produced in three classifications: no contour passes, single contour passes, and contours with secondary healing passes. Surface roughness was evaluated using line scan profilometry and subsurface porosity by optical microscopy. Contouring reduced the average surface roughness from Ra ≅ 25 μm to Ra ≅ 5 μm, and the layer of subsurface porosity introduced by this process could be partially eliminated by a secondary healing pass. One set of processing conditions from each contour class was selected for fatigue studies (R = -1), and their results were compared with the fatigue data from machined and polished specimens to evaluate the relative influence of surface condition. Relative to machined and polished specimens, fatigue lives are approximately five times lower for contoured specimens (with and without a healing pass) and twenty times lower for non-contoured specimens at equivalent stress levels up to 107 cycles to failure. Fractographic measurements of initial defect √area of all specimens reveal that fatigue behavior is well characterized by stress intensity factor amplitude across all surface conditions. An extreme value statistical method is developed using profilometry data to predict S-N curves, and it is concluded that non-destructive surface roughness measurements may be suitable for estimating the fatigue lives of components with as-fabricated surfaces as a rapid method for quality control.

Detection Method for Bolt Loosening and Washer Damage in Flange Assembly Structures Based on Phased Array Ultrasonics

ABSTRACT During the service life of flange assembly components, factors such as corrosion and vibration can lead to washer damage and loosening of fastening bolts, resulting in fluid leakage. Traditional inspection methods are not applicable for assessing the extent of washer damage and bolt loosening due to the non-dismantlable nature of flanges and the challenges posed by the working environment. To address these issues, this paper proposes a detection method utilizing phased array ultrasonic testing (PAUT). By analyzing the peak and side-lobe states of reflected signals, the extent of washer damage can be determined. A mathematical relationship is established between the depth of washer defects and the peak reflection amplitude, enabling the assessment of washer damage in flange structures. This method facilitates the measurement of the positions of washer damage and bolt loosening in flange structures, providing technical support for practical industrial applications.

Study of erosion-induced leakage flow in guide vane of Francis turbine using erosion-coupled mesh deformation simulations

Erosion of the hydro-turbine components in sediment-laden flows results in a reduction in the efficiency and life of turbine components. The particles in the water affect the operation of both stationary and dynamic components. In the present study, the guide vanes and facing plates of a Francis turbine are numerically investigated regarding their susceptibility towards erosion using an erosion-induced geometry deformation approach. The effects of non-uniform changes in the clearance gap between the guide vanes and facing plates on the erosion and leakage flow are explored. A segment of the actual distributor is analysed for the design and part load operation of the turbine. The simulations were performed for a period equivalent to 2400 h and the comparisons are drawn with the geometry at the end of 240 and 1200 h, respectively. The results show an increase in thickness loss with operation time, however, the position of maximum thickness loss shifted towards the tailing edge for guide vanes and towards center for the face plate. The increase in clearance gap leads to higher cross-flow across the clearance gap and thus, the crossflow and the erosion rate feed off each other. The erosion of the guide vane and face plate was symmetric for BEP but asymmetric for PL. Further, the simulations were performed with three different initial clearance gaps ranging from 0.5 mm to 1.5 mm highlighting the changes in erosion rate for different clearances. The present work provides important engineering insights for the design and operation of the Francis turbine guide vanes to control their erosion and leakage flow.

A P–S–N curve fitting method based on mixed Weibull distribution and expectation-maximization algorithm

In practical engineering, there are many factors affecting the fatigue life of actual components, and a single Weibull distribution is insufficient to accurately describe the impact of various factors on fatigue life. In order to solve the above problems, 316L stainless steel is taken as the experimental object to study the effects of phase difference and stress levels on fatigue life based on the mixed Weibull distribution model. Firstly, the mixed Weibull distribution model is converted into the mixed extreme value distribution model, and used Euler's constant to calculate relevant parameters of extreme value distribution and Expectation-Maximization (EM) algorithm to determine the probability density function of the mixed Weibull distribution. Secondly, the probability density function is integrated to obtain the distribution function and the fatigue life under different failure probabilities is calculated. Finally, the influence of non-proportional additional reinforcement and stress amplitude on fatigue life is studied by taking them as hidden variables of mixed Weibull distribution, which is used to obtain P-S-N curves for various failure probabilities. Through the proposed method, the influence of different factors on fatigue life can be considered from the perspective of statistics, and the accuracy of fatigue life prediction can be promoted.

On the Polygonal Wear Evolution of Heavy-Haul Locomotive Wheels due to Wheel/Rail Flexibility and Its Mitigation Measures

Wheel polygonal wear can immensely worsen wheel/rail interactions and vibration performances of the train and track, and ultimately, lead to the shortening of service life of railway components. At present, wheel/rail medium- or high-frequency frictional interactions are perceived as an essential reason of the high-order polygonal wear of railway wheels, which are potentially resulted by the flexible deformations of the train/track system or other external excitations. In this work, the effect of wheel/rail flexibility on polygonal wear evolution of heavy-haul locomotive wheels is explored with aid of the long-term wheel polygonal wear evolution simulations, in which different flexible modeling of the heavy-haul wheel/rail coupled system is implemented. Further, the mitigation measures for the polygonal wear of heavy-haul locomotive wheels are discussed. The results point out that the evolution of polygonal wear of heavy-haul locomotive wheels can be veritably simulated with consideration of the flexible effect of both wheelset and rails. Execution of mixed-line operation of heavy-haul trains and application of multi-cut wheel re-profiling can effectively reduce the development of wheel polygonal wear. This research can provide a deep-going understanding of polygonal wear evolution mechanism of heavy-haul locomotive wheels and its mitigation measures.

Characterization and comparison of cobalt-base and nickel-base alloys with iron-base intermetallic hard alloys used in wear protection

Abstract In wear protection, cobalt-base or nickel-base materials are very often used for coatings in order to increase the functionality and service life of components. These materials such as stellite, the nickel-base alloy Colmonoy 56 or Tribaloy T400 are characterized by a high resistance to abrasion, adhesion as well as excellent corrosion resistance even at higher temperatures. Given the criticality of cobalt and partly also nickel, it is necessary to look for more sustainable alternatives to be used in wear protection. One possibility is to further develop iron-base materials so that they can be used in wear protection to prevent both abrasion and adhesion. In this context, sufficient corrosion resistance is desirable. This paper will elaborate on the development of a novel intermetallic iron-base hard alloy.