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16 pages, 4087 KiB

Open AccessArticle

Estimation Strategy of RUL Calculation in the Case of Crack in the Magnets of PMM Used in HEV Application

by Riham Ginzarly, Ghaleb Hoblos and Nazih Moubayed

Appl. Sci. 2023, 13(6), 3694; https://doi.org/10.3390/app13063694 - 14 Mar 2023

Viewed by 1230

Knowing the importance of assuring their reliability and availability, prognosis and remaining useful life calculation (RUL) concepts are highly suggested to be applied in critical applications such as hybrid electric vehicles (HEV). In the electrical propulsion system of HEVs, the electrical machine is [...] Read more.

Knowing the importance of assuring their reliability and availability, prognosis and remaining useful life calculation (RUL) concepts are highly suggested to be applied in critical applications such as hybrid electric vehicles (HEV). In the electrical propulsion system of HEVs, the electrical machine is one of the most critical elements considering its cost and function. Most electrical machines used in HEVs are permanent magnet machines (PMM). Most severe faults in PMM that affect its normal operation are the result of demagnetization. However, applying prognosis to a real prototype to detect the presence of mechanical defects such as cracks in the magnet of PMM and calculating the RUL of this defective element are challenging. In this paper, we are going to take advantage of a finite element model already built for the PMM in the healthy state and the state where cracks of different depths are integrated into the magnet. After that, relevant vital parameters that are affected when this type of fault persists in the machine are collected. Then, prognosis is applied to detect the presence of the crack in one piece of magnet in the electrical machine. Following this, the RUL calculation is performed to predict the remaining time before the crack propagates and a total fracture occurs in the magnet. The method used to execute the prognosis is the hidden Markov model (HMM). The RUL calculation will be performed using Paris equation, being the most important equation that models the growth and propagation of cracks Full article

(This article belongs to the Special Issue Focus on Fatigue and Fracture of Engineering Materials)

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21 pages, 7073 KiB

Open AccessArticle

Finite Element Analysis of the Influence of Chamfer Hub Geometry on the Stress Concentrations of Shrink Fits

by Eulalia Izard, Roberto García-Martín, Manuel Rodríguez-Martín and Miguel Lorenzo

Appl. Sci. 2023, 13(6), 3606; https://doi.org/10.3390/app13063606 - 11 Mar 2023

Cited by 1 | Viewed by 2091

Abstract

The theoretical expressions commonly used in the design of interference fits do not take into account the huge stress concentrations located at the edges of the hub. This underestimation of the real stress state can induce the incorrect performance of the shaft–hub assembly. [...] Read more.

The theoretical expressions commonly used in the design of interference fits do not take into account the huge stress concentrations located at the edges of the hub. This underestimation of the real stress state can induce the incorrect performance of the shaft–hub assembly. Among the different methods to address this problem is the use of chamfer hubs, which are used for reducing such stress concentrations. In this paper, an analysis, performed via finite element method, of the influence of the geometric parameters of a shrink fit with chamfer hubs was carried out with the aim of determining the optimal dimensions for the design of this type of mechanical assembly. To achieve this goal, different chamfer hub geometries were considered: (i) full–chamfer hubs defined by the chamfer angle and (ii) partial–chamfer hubs defined by the chamfer angle and the chamfer height. According to the obtained results, stress concentrations can be reduced by using a full–chamfer hub with chamfer angles within the range 13°–15° depending on the hub thickness. In addition, similar results can be obtained by using partial–chamfer hubs with a chamfer height of half of the hub thickness and chamfer angles within the range 13°–15°. By using these design recommendations, the theoretical equations can be used without underestimating the real stress state. Full article

(This article belongs to the Special Issue Focus on Fatigue and Fracture of Engineering Materials)

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12 pages, 4202 KiB

Open AccessArticle

Microstructure and Fracture Behaviors of Oscillating Laser Welded 5A06 Aluminum Alloy Lock Butt Joint

by Yang Lu, Jian Lai, Junping Pang, Xin Li, Chen Zhang and Ming Gao

Appl. Sci. 2023, 13(6), 3381; https://doi.org/10.3390/app13063381 - 7 Mar 2023

Viewed by 1453

Abstract

Oscillating laser welding is potential to improve the quality of aluminum alloy joints, but has been seldom addressed on lock butt joint. In this paper, the effects of beam oscillation frequencies (f) on the properties of laser-welded 5A06 aluminum alloy lock [...] Read more.

Oscillating laser welding is potential to improve the quality of aluminum alloy joints, but has been seldom addressed on lock butt joint. In this paper, the effects of beam oscillation frequencies (f) on the properties of laser-welded 5A06 aluminum alloy lock butt joints were investigated, especially those at the lock step. In the microstructure, the columnar grain zone (CGZ) near the fusion line narrowed, the porosity was reduced, and the angle between lock step and fusion line increased with the increase of f. Correspondingly, the fracture changed from equiaxed grain zone to heat affected zone (HAZ), and the fracture angle between lock step and crack propagation line from 90° to 45°. The maximum ultimate tensile strength and elongation of oscillating weld reached 308 MPa and 18.2%, respectively, 36.3% and 203.3% higher than non-oscillating weld. The fracture behaviors indicated that the crack always initiated at the lock step, and then preferably propagated to the pores, followed closely by the weaker CGZ, and then the stronger HAZ when CGZ was narrowed enough. Notably, when the pore size was small (<0.39 mm) and located below the lock step, the pore was not on the crack propagation path. The crack tended to propagate towards the weaker CGZ. Finally, the fracture mechanism was discussed. The results clarify the fracture mechanism of oscillating laser-welded lock butt joints and contribute to the development of oscillating laser welding. Full article

(This article belongs to the Special Issue Focus on Fatigue and Fracture of Engineering Materials)

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12 pages, 3802 KiB

Open AccessArticle

Assessment of Changes in the Abrasiveness of Solid Particles in Hydraulic Mixtures Pumped with ESPs

by Dmitriy Shishlyannikov, Ivan Zvonarev, Alexander Rybin, Valeriy Zverev and Anna Ivanchenko

Appl. Sci. 2023, 13(3), 1885; https://doi.org/10.3390/app13031885 - 1 Feb 2023

Cited by 7 | Viewed by 1655

Abstract

The statistics of using downhole electric submersible pump (ESP) units in the oil fields of Eurasia show that hydroabrasive wear is a common cause of ESP emergency failures. The authors of this study theoretically and experimentally investigated the peculiarities of water–abrasive wear of [...] Read more.

The statistics of using downhole electric submersible pump (ESP) units in the oil fields of Eurasia show that hydroabrasive wear is a common cause of ESP emergency failures. The authors of this study theoretically and experimentally investigated the peculiarities of water–abrasive wear of ESP components. The research methodology and construction of the laboratory bench are described, and the results of experimental studies of determination of changes in the abrasivity index of impurity particles contained in the mixture pumped with the working stages of an ESP section are given. It is shown that large particles of mechanical impurities in contact with the metal of the working stages are subjected to intensive grinding of up to 0.25…0.3 mm; after that, particle size remains practically unchanged. An increased abrasiveness index of mechanical impurities causes an increase in the intensity of wear of interstage seals along the flow of a water–abrasive mixture (from the inlet to the outlet of the pumping section). Based on the obtained results, recommendations for selection of devices for formation-fluid cleaning during development and operation of oil wells are given. The relevance of work on improving the design of interstage seals of ESP units is substantiated. Full article

(This article belongs to the Special Issue Focus on Fatigue and Fracture of Engineering Materials)

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14 pages, 4753 KiB

Open AccessArticle

A Computational Framework for 2D Crack Growth Based on the Adaptive Finite Element Method

by Abdulnaser M. Alshoaibi and Yahya Ali Fageehi

Appl. Sci. 2023, 13(1), 284; https://doi.org/10.3390/app13010284 - 26 Dec 2022

Cited by 2 | Viewed by 1991

Abstract

As a part of a damage tolerance assessment, the goal of this research is to estimate the two-dimensional crack propagation trajectory and its accompanying stress intensity factors (SIFs) using the adaptive finite element method. The adaptive finite element code was developed using the [...] Read more.

As a part of a damage tolerance assessment, the goal of this research is to estimate the two-dimensional crack propagation trajectory and its accompanying stress intensity factors (SIFs) using the adaptive finite element method. The adaptive finite element code was developed using the Visual Fortran language. The advancing-front method is used to construct an adaptive mesh structure, whereas the singularity is represented through construction of quarter-point single elements around the crack tip. To generate an optimal mesh, an adaptive mesh refinement procedure based on the posteriori norm stress error estimator is used. The splitting node strategy is used to model the fracture, and the trajectory follows the successive linear extensions for every crack increment. The stress intensity factors (SIFs) for each crack extension increment are calculated using the displacement extrapolation technique. The direction of crack propagation is determined using the theory of maximum circumferential stress. The present study is carried out for two geometries, namely a rectangular structure with two holes and one central crack, and a cracked plate with four holes. The results demonstrate that, depending on the position of the hole, the crack propagates in the direction of the hole due to the unequal stresses at the crack tip, which are caused by the hole’s influence. The results are consistent with other numerical investigations for predicting crack propagation trajectories and SIFs. Full article

(This article belongs to the Special Issue Focus on Fatigue and Fracture of Engineering Materials)

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14 pages, 4109 KiB

Open AccessArticle

Finite Element Analysis of the Reduction in Stress Concentration Factors in Shrink Fits by Using Contact Rings

by Eulalia Izard, Roberto Garcia, Manuel Rodriguez-Martín and Miguel Lorenzo

Appl. Sci. 2022, 12(19), 10037; https://doi.org/10.3390/app121910037 - 6 Oct 2022

Cited by 3 | Viewed by 2778

Abstract

As it is well known, shrink fits exhibit a stress concentration at the hub edges that can cause the failure of such mechanical components. A method for reducing such a stress concentration is placing a contact ring between the hub and the shaft. [...] Read more.

As it is well known, shrink fits exhibit a stress concentration at the hub edges that can cause the failure of such mechanical components. A method for reducing such a stress concentration is placing a contact ring between the hub and the shaft. To achieve the desired effect, the Young Modulus of the material used for the contact ring must be lower than the one used in the hub and the shaft. Unfortunately, there are no design methods for estimating the optimal dimensions or materials of the contact ring. To fill this gap, in this study, diverse numerical simulations by the finite elements method (FEM) were carried out considering different geometries and materials in order to obtain recommendations that allow mechanical designers to significantly reduce the stress concentrations in these components. According to the obtained results, a contact ring of 25% of the hub thickness allows to significantly reduce up to 40% of the stress concentration. In addition, a linear influence of the stress reduction with the Young modulus was found thereby, and the most recommendable material for the contact ring is the one with the lowest Young modulus. On the other hand, according to the obtained results, the influence of the Poisson coefficient can be considered negligible. Full article

(This article belongs to the Special Issue Focus on Fatigue and Fracture of Engineering Materials)

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17 pages, 5538 KiB

Open AccessFeature PaperArticle

Influence of Local Properties on Fatigue Crack Growth of Laser Butt Welds in Thin Plates of High-Strength Low-Alloy Steel

by Patricio G. Riofrío, Joel de Jesus, José A. M. Ferreira and Carlos Capela

Appl. Sci. 2021, 11(16), 7346; https://doi.org/10.3390/app11167346 - 10 Aug 2021

Cited by 3 | Viewed by 1843

Abstract

In this work, local properties such as hardness and fatigue crack grow rate in the heat-affected zone of four laser-welded butt joints in thin high-strength low-alloy steel were examined, so as to explain and predict fatigue lives at high stress levels through the [...] Read more.

In this work, local properties such as hardness and fatigue crack grow rate in the heat-affected zone of four laser-welded butt joints in thin high-strength low-alloy steel were examined, so as to explain and predict fatigue lives at high stress levels through the fracture mechanics approach. The different welded series presented a similar fatigue crack growth rate in the heat-affected and fusion zones, but lower than base metal due to the higher hardness of the bainitic–martensitic microstructure verified in the welded series. The results showed that at high stress levels in the as-welded condition, the fatigue initiation stage can be neglected and assume some types of cracks, with an initial crack of 0.07 mm and appropriate fatigue crack growth rates, estimates of fatigue life close to the experimental results were obtained. Full article

(This article belongs to the Special Issue Focus on Fatigue and Fracture of Engineering Materials)

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15 pages, 5042 KiB

Open AccessArticle

Application of Fatigue Damage Evaluation Considering Linear Hydroelastic Effects of Very Large Container Ships Using 1D and 3D Structural Models

by Sang-Ick Lee, Seung-Hwan Boo and Beom-Il Kim

Appl. Sci. 2021, 11(7), 3001; https://doi.org/10.3390/app11073001 - 27 Mar 2021

Cited by 7 | Viewed by 2378

Abstract

Owing to the increasing size and speed of ships to ensure economic efficiency, the hydroelastic phenomena of the hull have emerged as an important factor to be considered in the evaluation of strength during the design stage of current ship building procedures. In [...] Read more.

Owing to the increasing size and speed of ships to ensure economic efficiency, the hydroelastic phenomena of the hull have emerged as an important factor to be considered in the evaluation of strength during the design stage of current ship building procedures. In this study, we established a method to evaluate fatigue strength with linear spring effects using a 1D (one-dimensional) beam model and a 3D (three-dimensional) global Finite Element (FE) model. Firstly, FSI (fluid–structure interaction) analysis was carried out using the 1D beam model of a 15,000 twenty equivalent unit (TEU) container ship. In this step, the method proposed was to calculate the stress RAO (Response Amplitude Operator) of the hot spot points using only the hull girder load from the beam model. Next, a modal superposition analysis was carried out using the 3D global FE model that was directly calibrated to the fatigue damage of the hot spot points. Based on these stress transfer functions with hydroelastic effects, spectral fatigue analysis was carried out, and the portion of linear springing effects in the fatigue damage was analyzed, respectively. These results were compared with the rigid-body-based results in the final design stage. Finally, the applicability of the proposed method at the actual design stage is discussed. Full article

(This article belongs to the Special Issue Focus on Fatigue and Fracture of Engineering Materials)

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