Articles
Publication Date: 2026
Mechanical Systems and Signal Processing (0888-3270)247
Accurate and reliable estimation of bearing health conditions requires the construction of a suitable Health Indicator (HI). In this study, the Modified Total Harmonic Distribution (MTHD) health indicator is developed based on advanced frequency domain analysis to describe the bearing health status effectively. It has also been validated that MTHD demonstrated desirable properties of monotonicity, robustness, and trendability. To accurately identify the First Prediction Time (FPT), a linear combination of the mean and variance of the MTHD curve is employed. However, due to variations in operating conditions and loading, the degradation process of bearings may differ. As a result, a single fixed model cannot accurately characterize the occurrence of different degradation processes. To address this issue, an adaptive Wiener model is proposed. In this framework, the Remaining Useful Life (RUL) prediction is achieved using either an appropriate linear or nonlinear Wiener model selected through a model adaptive algorithm. Finally, the effectiveness of the proposed model is validated using the XJTU-SY bearing dataset as well as the laboratory's own generated dataset. © 2026 Elsevier Ltd
Publication Date: 2026
International Journal of Engineering, Transactions B: Applications (1728144X)39(1)pp. 44-58
Bevel gears are a kind of gears that transmit power between two intersecting shafts. Bevel gears with Octidal and spherical involute profiles are the most common types of bevel gears. The profile of spherical involute teeth is a three-dimensional complex surface, requiring an accurate geometric definition calculation. Due to this complex geometry, modeling, stress-strain analysis, and mesh stiffness calculation are very difficult. In this study by extracting Napier’s Equations from the tooth profile geometry, geometric parameters of the spherical involute curve have been calculated. The results show that the pitch cone angle has an important effect on the shape of the spherical involute curve, so choosing the correct angle is particularly important. A significant increase in the azimuthal angle is observed by increasing the polar angle. In addition, increasing the angle of the pitch cone reduces the curvature of the side surfaces of the teeth and facilitates the manufacturing process. On the other hand, reducing the pressure angle will result in flat lateral surfaces and a tooth shape similar to the octoidal tooth. The sphere radius variations do not affect the shape of the tooth and only change the size of the tooth. Finally, a gear system comprising a pinion and gear was made from Polylactic Acid (PLA) utilizing the calculated angles to verify the accuracy of computed angles. Also, experimental and finite element methods determined the pinion and gear contact pattern. There was a good agreement between the finite element simulation and the experimental observation. ©2026 The author(s).
Publication Date: 2025
Arabian Journal for Science and Engineering (21914281)50(4)pp. 2663-2689
Parametric study of ductile material forming processes for optimization of damage that occurs in the production stages of the parts will lead to better quality, performance, durability, and reduced production costs. Additionally, implementing an appropriate criterion that accurately predicts and simulates damage growth in the production of a part is an essential step in the optimization process. This research investigates the optimization and minimization of the final damage in a gudgeon pin produced by a two-stage cold extrusion process. First, numerical simulations are performed using the modified Lemaitre’s damage criterion, which provides an accurate estimate of damage growth in combined tensile and compressive loads. In the following, two methods for optimizing the parameters of each extrusion cold die are examined, and the magnitude of the final damage in the product is compared. In the first method, the design of the Taguchi experiment is implemented. In the second method, by implementing and training an artificial neural network and transferring the results to the genetic algorithm, the optimization of the die parameters is investigated to minimize the final damage in the product. A comparison of the results in the two mentioned methods shows that the final damage in the product is less than the critical damage value in both methods. Also, the neural network method will lead to less final damage in the product in comparison with the design method of the Taguchi experiment. © King Fahd University of Petroleum & Minerals 2024.
