@article { author = {Ghoudjani, Mohamadjavad and Rafieian, Farzad and Mohammadebrahim, Abolfazl and Jalali, Hassan}, title = {Instantaneous Angular Speed (IAS) signal for abnormal combustion diagnosis in an I.C. engine}, journal = {Journal of Theoretical and Applied Vibration and Acoustics}, volume = {7}, number = {1}, pages = {1-14}, year = {2021}, publisher = {Iranian Society of Acoustics and Vibration and Avecina}, issn = {2423-4761}, eissn = {2783-0888}, doi = {http://dx.doi/10.22064/tava.2021.540989.1195}, abstract = {This paper is about the application of instantaneous angular speed (IAS) signal in a 3-liter six-cylinder gasoline engine. The study is in continuation of former work in which a measurement system was developed for this signal on a rotating machine. The future trend of the research is to measure IAS in an I.C. engine. Therefore, the objective of the current work is to provide a verified software tool which can run simulated experiments with IAS signal output under healthy/faulty conditions. An engine model with detailed crankshaft elements is established in the GT-SUITE[1] software. Under the GT-SUITE environment, IAS signal output is obtained through simulated experiments. In order to validate the tool, the first torsional natural frequency of the crankshaft obtained from frequency analysis on the IAS signal is compared with the result of modal analysis on the crankshaft structure using the F.E. method. Also, the value is compared with the prediction from the GT CrankAnalysis module. A good match is found, which shows the validity of the developed software tool. Faulty condition of misfiring in one cylinder is simulated using this tool, and expected observations on the IAS output signal are verified to address the future trend of the research using the developed tool in this study.  }, keywords = {Instantaneous angular speed,I.C. engine,Torsional vibrations,Fault diagnosis}, url = {https://tava.isav.ir/article_247384.html}, eprint = {https://tava.isav.ir/article_247384_9b1f869181a37c7c3a8bc078dccd6e72.pdf} } @article { author = {Azimi, Seyed Alireza and Mardanshahi, Ali and Kazemirad, Siavash}, title = {Nondestructive thickness mapping of corroded plate structures using guided lamb wave propagation}, journal = {Journal of Theoretical and Applied Vibration and Acoustics}, volume = {7}, number = {1}, pages = {15-28}, year = {2021}, publisher = {Iranian Society of Acoustics and Vibration and Avecina}, issn = {2423-4761}, eissn = {2783-0888}, doi = {10.22064/tava.2022.540517.1194}, abstract = {Nondestructive evaluation (NDE) of thickness loss in plate structures is an important monitoring task. A two-step NDE method for rapid and reliable corrosion mapping of plate structures using the Lamb wave propagation is proposed in this study. The analytical model for thickness mapping via the Lamb wave propagation was presented. One strip and one plate specimen with varying thickness profiles were fabricated from steel and then tested. The A0 Lamb wave mode was propagated in the fabricated specimens with an excitation frequency of 60 kHz. The Lamb wave velocity and thus the Lamb wavenumber were first measured experimentally, which were used to estimate the thickness of the specimens for each measurement span from the numerical solution of the presented Lamb wave propagation model. The approximate mean thickness of the specimens within the corrosion zone was estimated in the first measurement step, while the mapping of the thickness profile of the corrosion zone was performed in the second measurement step. The mean thickness and the thickness profile of the corrosion zone estimated from the proposed method were found to be in good agreement with the actual mean thickness and thickness profile for both of the strip and plate specimens. Thus, it was concluded that the proposed Lamb wave propagation method can be utilized as a strong nondestructive evaluation tool for rapid thickness mapping of corroded plate structures.}, keywords = {Ultrasound,NDE,Corrosion,Guided wave tomography}, url = {https://tava.isav.ir/article_252499.html}, eprint = {https://tava.isav.ir/article_252499_b67afa311b047249bc5e31fd58f4464d.pdf} } @article { author = {Fathzadeh, Mehran and Saberi, Mohammad and Ajri, Masoud and A. Shirazi, Farzad}, title = {Vibration simulation and fatigue life estimation of a printed circuit board using a validated model}, journal = {Journal of Theoretical and Applied Vibration and Acoustics}, volume = {7}, number = {1}, pages = {29-42}, year = {2021}, publisher = {Iranian Society of Acoustics and Vibration and Avecina}, issn = {2423-4761}, eissn = {2783-0888}, doi = {10.22064/tava.2021.532675.1185}, abstract = {An electronic package consists of printed circuit boards (PCBs) placed in a casing joined together. Electronic circuit boards should operate properly in different conditions including thermal cycling, vibrations, and mechanical shock. Printed circuit boards require to be analyzed electrically as well as mechanically for optimized performance. In this paper, the finite element analysis (FEA) of a PCB is carried out in ANSYS and the results are validated utilizing modal testing. The natural frequencies and mode shapes of the PCB are determined, and the effect of mechanical shock on the PCB is also evaluated. The results demonstrate that the PCB has three resonance frequencies in the range of 0-1000 Hz. The mode shapes related to each natural frequency are also obtained employing ANSYS software. These data can be used for fatigue life estimation and mechanical shock analysis. In this work, the fatigue life estimation of wires and solder joints under sinusoidal and random vibrations are estimated as well by using the Steinberg's method. The results illustrate that random vibration has more impact than harmonic vibration on the fatigue life of solder joints and wires according to the Peugeot standard. Also, the results have passed the Peugeot standard qualification in both random and harmonic vibrations.}, keywords = {finite element analysis,printed circuit board,modal testing,fatigue life estimation,Steinberg' s method}, url = {https://tava.isav.ir/article_252498.html}, eprint = {https://tava.isav.ir/article_252498_a280e8494ed9fe86cf4470c0da149bcb.pdf} } @article { author = {Honarvar, Farhang and Shabani, Ramin}, title = {Variations of ultrasonic wave attenuation in thick-walled cylinders subjected to a thermal gradient}, journal = {Journal of Theoretical and Applied Vibration and Acoustics}, volume = {7}, number = {1}, pages = {43-54}, year = {2021}, publisher = {Iranian Society of Acoustics and Vibration and Avecina}, issn = {2423-4761}, eissn = {2783-0888}, doi = {10.22064/tava.2022.554349.1203}, abstract = {Accurate ultrasonic testing of engineering components like pressure vessels, which are subjected to extreme condition such as high stresses, high temperatures, and thermal gradients is important. Wave velocity and attenuation are two major parameters in ultrasonic testing. In this paper, a mathematical model is developed for calculation of the absolute attenuation of longitudinal waves in thick-walled cylinders that are subjected to thermal gradients. The cylinder is assumed to be homogeneous and isotropic. The independent variables are cylinder inner and outer radii, incidence angle and temperature of the inner surface of the cylinder in the range of 300-800 K. Based on the results obtained from the theoretical model, the wave attenuation is found to be highly sensitive to inner-surface temperature of the cylinder; however, the overall variation of the attenuation with respect to changes of the incidence angle and inner and outer radii of the cylinder is only 2 dB/m, which is ignorable in most practical applications. Furthermore, in the presence of a thermal gradient, there is an inverse relationship between the cylinder thickness and attenuation coefficient. The mathematical model is verified by using the experimental data available in the literature}, keywords = {Axial scanning,Ultrasonic Waves,Absolute attenuation,Thermal gradient,thick-walled cylinder}, url = {https://tava.isav.ir/article_697943.html}, eprint = {https://tava.isav.ir/article_697943_c408e5eafb0d60dffd361961d0bb9284.pdf} } @article { author = {Behzad, Mehdi and Izanlo, Hassan and Davoodabadi, Ali and Arghand, Hesam Addin}, title = {Fault detection of rolling element bearing using a temporal signal with artificial intelligence techniques}, journal = {Journal of Theoretical and Applied Vibration and Acoustics}, volume = {7}, number = {1}, pages = {55-71}, year = {2021}, publisher = {Iranian Society of Acoustics and Vibration and Avecina}, issn = {2423-4761}, eissn = {2783-0888}, doi = {10.22064/tava.2022.552939.1202}, abstract = {Fault detection of rolling element bearing (REB), has a very effective role in increasing the reliability of machinery and improving future decisions for rotating machinery operation. In this study, a new method based on a convolutional neural network (CNN) is developed for fault detection of REB. Its performance will be compared with other artificial intelligence (AI) techniques, 2-layer, and deep feedforward neural network (FFNN). In this regard, a set of accelerated-life tests has been implemented on an experimental platform. The models are aimed to recognize the impact pattern in the raw signals generated by faulty REBs. The innovation of the present study is to convert the high-dimensional input as a raw temporal signal to low-dimensional output. The developed method does not need preprocessing of data.  Using several types of accelerated tests prevents overfitting. The result shows that the accuracy of the developed CNN-based method is 98.6% for all data sets and 94.6% for the validation dataset. The accuracy of the 2-layer FFNN is 85% for all datasets and 74.2% for the validation dataset and the accuracy of the deep FFNN is 82% for all datasets and 67% for the validation dataset. Therefore, the developed CNN-based method has better performance than the FFNN-based models.}, keywords = {fault detection,rolling-element bearing,Convolutional neural network,Feed-forward neural network,impact detection}, url = {https://tava.isav.ir/article_699737.html}, eprint = {https://tava.isav.ir/article_699737_58e15e8a0b5f1b610992792708e62d97.pdf} } @article { author = {Peyman, Safa and Eskandari, Amir}, title = {Investigation of dynamic-thermal stress intensity factor in functionally-graded plates having an edge crack}, journal = {Journal of Theoretical and Applied Vibration and Acoustics}, volume = {7}, number = {1}, pages = {72-87}, year = {2021}, publisher = {Iranian Society of Acoustics and Vibration and Avecina}, issn = {2423-4761}, eissn = {2783-0888}, doi = {10.22064/tava.2023.563129.1211}, abstract = {Functionally graded materials (FGMs) are non-homogeneous materials whose properties gradually vary as a function of coordinates. Recently, due to the possibility of applying FGMs in conditions with severe temperature changes, e.g., nuclear reactors, chemical power plants, and space crafts, the interest in investigations on this type of material has increased considerably. Usually, FGMs are designed to tolerate drastic temperature changes and thermal shocks are mainly associated with thermal stresses. Therefore, the occurrence of thermal fracture in FGMs is probable. Consequently, studying the fracture mechanics of this type of material under extreme thermal shocks and dynamic loads has become crucial. This paper studies the first mode stress intensity factor (SIF) in FGM plates with an edge crack under thermal shock and dynamic loading. The plates consist of Nickel (metal) and Zirconia (ceramic) properties on top and bottom, respectively. The finite element method is employed to perform dynamic thermal analyses of the plates. Having known that variations in the amount of metal and ceramic used in producing an FGM plate can change its behavior, different gradients of material properties are applied for modeling the FGM plates. Then, the effects of the variation of the gradients on the dynamic-thermal SIF under thermal shocks and dynamic loadings are examined. One of the novelties of the present study is modeling the required material properties for thermal analyses (heat transfer coefficient, specific heat, and thermal expansion coefficient) and dynamic analyses (elasticity modulus, Poisson's ratio, and density) as functions, which have been rarely considered simultaneously in the previous studies.}, keywords = {Functionally-Graded Material,Edge Crack,Dynamic-Thermal Stress Intensity Factor,finite element method}, url = {https://tava.isav.ir/article_702301.html}, eprint = {https://tava.isav.ir/article_702301_6195ae4e6da800f89c73de6ea16709ec.pdf} }