Damage Mechanics
V. Samadi; M. Mostafaei; A. N. Lorestani
Abstract
This study presents a non-invasive method for detecting mechanical faults in a single-phase AC electromotor using processed acoustic signals. Sound data were collected via a USB-connected microphone installed in the motor's electrical casing under diverse operating conditions. Ten statistical features ...
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This study presents a non-invasive method for detecting mechanical faults in a single-phase AC electromotor using processed acoustic signals. Sound data were collected via a USB-connected microphone installed in the motor's electrical casing under diverse operating conditions. Ten statistical features were extracted from the acoustic signals and used as input to three classification algorithms: Linear Discriminant Analysis (LDA), Quadratic Discriminant Analysis (QDA), and Support Vector Machine (SVM). Model performance was evaluated using confusion matrix metrics, including specificity, accuracy, precision, and sensitivity. Among the classifiers, SVM outperformed others, achieving average values of 99.54, 99.16, 97.15, and 96.17, respectively, with 10-fold cross-validation confirming its superior consistency (99.88% specificity, 99.17% accuracy). The findings confirm that acoustic signal analysis is a reliable and cost-effective tool for real-time fault diagnosis in electromotors. Defects may be accurately found in the electromotor by using acoustic analysis to monitor its status. The proposed framework is adaptable to other rotating machinery through retraining, offering a valuable solution for predictive maintenance in industrial applications.
Daynamics
Vinh V. Nguyen; Trung N. Nguyen; Chi T. Nguyen
Abstract
Information about the dynamic loading of a steel structure is important for its static design as well as for an assessment of its fatigue life. In the case of a hydraulic static-pile-pressing machine, these loads are mainly caused by vibrations and load sway, which occurs as a result of the slewing motion ...
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Information about the dynamic loading of a steel structure is important for its static design as well as for an assessment of its fatigue life. In the case of a hydraulic static-pile-pressing machine, these loads are mainly caused by vibrations and load sway, which occurs as a result of the slewing motion of the boom around the vertical axis and from the radial movement of the load’s suspension point. This paper presents the study of the dynamics of a hydraulic static-pile-pressing machine during the process of lifting and slewing a pile using a mounted crane. A six-degree-of-freedom non-linear spatial-dynamic model is employed and a non-linear mathematical model of the machine is formulated. To confirm the mathematical model, the comparison between the measured results and simulation results using the mathematical model shows that the mathematical model is reliable. These results can be used to optimize the machine design based on calculations of its dynamics, fatigue, life expectancy and stability from a dynamic point of view.
Damage Mechanics
H. El Bhilat; K. El Had; H. Salmi; A. Hachim
Abstract
In this study, the effect of six successive recycling cycles of the recycled material including high impact polystyrene disposable cups on tensile properties, glass transition temperature, flexural, impact strength tests and fluidity were studied. It has been found that after increasing recycling, the ...
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In this study, the effect of six successive recycling cycles of the recycled material including high impact polystyrene disposable cups on tensile properties, glass transition temperature, flexural, impact strength tests and fluidity were studied. It has been found that after increasing recycling, the molar mass and the viscosity decrease (a slight increase of melt flow index) until the fifth cycle; the maximum yielding stress decreased due to material brittleness.The impact strength has only been relatively influenced by a 17% increase, whereas the elongation at break and the Young’s modulus dropped with reprocessing cycles. Glass transition temperature has undergone a remarkable decrease: It dropped in a consistent way by the sixth cycle we measured a drop of almost 11°C was compared to the virgin material, with a notable increase in flexural modulus and hardness. The resulted curves show the reliability of this material to be used after a specific number of processing in several industrial applications.
Damage Mechanics
E. Homaei; K. Farhangdoost; M. Akbari
Abstract
The aim of the study was to find the optimum combination of materials and thicknesses to provide a tough, damage resistant multi-layer system with numerical methods to restore the damaged teeth. Extended Finite Element Method (XFEM) was used to assess the critical loads for the onset of damage modes ...
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The aim of the study was to find the optimum combination of materials and thicknesses to provide a tough, damage resistant multi-layer system with numerical methods to restore the damaged teeth. Extended Finite Element Method (XFEM) was used to assess the critical loads for the onset of damage modes such as radial cracks and plastic deformation in dental prostheses, which consist of a brittle outerlayer (porcelain)/ metal (Au, Pd, Co)-core/ substrate (dentin) trilayer system. XFEM not only has the ability to model crack initiation process, but also could solve crack propagation problems. Generally speaking, porcelain layer shouldn't be thinner than 0.5 mm, as the stresses due to bending become tensile critically in porcelain undersurfaces and radial cracks would occur in low loads. Also, it could be concluded that XFEM in axisymmetric model could properly estimate crack initiation and propagation path. Yielding of metal core makes additional flexural stress at overlaying brittle surface and consequently, facilitates radial cracks. In dental applications, the optimum porcelain thickness would be between 0.75 and 1.25 mm. Furthermore, yield strength and stiffness of metal is better to be high sufficiently to prevent it from plastic deformation and ensuing radial cracks.
