Influence of Conventional Shot Peening Treatment on the Service Life Improvement of Bridge Steel Piles Subjected to Sea Wave Impact

© 2023 The authors. Licensee MDPI, Basel, Switzerland. This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY), https://creativecommons.org/licenses/by/4.0/The first goal of the current study is to estimate the fatigue life of the middle steel piles of an integrated bridge installed in water and subject to the impact of sea waves. In the following, the authors have tried to improve the service life of this critical part of the bridge, which is also the main purpose of the study. To this end, conventional shot peening, as one of the most well-known surface treatments, was used. Axial fatigue tests were performed on samples fabricated from IPE-220 steel piles in two states without and with shot peening surface treatment. Next, the modified S-N curve was entered into the finite element software to define the effect of shot peening treatment. Different analysis, including thermal, thermal-structural coupled, and transient dynamic, were performed and various outputs were extracted for the entire structure. In all these analyses, changes in air temperature have been neglected. The most important achievement of this research is the discovery that motionless water cannot cause serious damage to steel piles. Moreover, application of conventional shot peening can increase the fatigue life of steel piles, or in other words the service life of the bridge, subjected to the impact of sea waves by about 22%.Peer reviewe

Fatigue life estimation under multi-axial random loading in light poles

In the present paper, fatigue life of light poles under multi-axial random loading based on the variable wind direction and speed has been studied. To achieve these purposes, light pole is simulated with all loading conditions in ABAQUS Software. To consider to the three storm days as the critical loading conditions, Random vibration analysis has been performed to obtain stress histories and equivalent stress. Finally, Calculate fatigue life of light pole by using Dirlik Theory

Failure Analysis of Marine Structure

© 2023 by the authors. Licensee MDPI, Basel, Switzerland. This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY), https://creativecommons.org/licenses/by/4.0/Peer reviewe

Application of Taguchi Approach to Forecast the Wages of Persian Silk Carpet Weavers

One of the remarkable phenomena in recent years is the growing trend of globalization. Iran is also seeking to join the World Trade Organization (WTO) to expand non-oil exports and presence in global markets, and is currently a member of the organization's oversight body. Handmade industries such as hand woven carpet are one of the important trades that can be studied for this purpose. Exports of handmade carpets have fluctuated over different time periods. Despite maintaining its international position as the rank of the largest exporter of handmade carpets, the export position of handmade carpets is decreasing as compared to other Iranian exports. Handmade carpet craftsmanship is a complementary activity of agricultural and rural businesses, but due to the considerable number of workers and the small share of carpet value added in the national economy, it does not have a suitable condition. Other influential parameters such as rivals (e.g., China, India, Pakistan, and Turkey), etc. have caused the economic conditions of this industry to be unstable. In this regard, one of the best and most appropriate ways to compete with other countries is to reduce production costs and, consequently, reduce product prices. This factor includes various variables, including weavers' wages. Unfortunately, there is no definite and elaborate program for determining the wages of handmade silk carpet weavers in Iran according to the standard. In fact, in some cities, the weavers' wages determine based on the texture conditions, texture parameters, economic conditions of the country, and other parameters by carpet wage boards that consist of several carpet experts. In this way, there is the possibility of mistakes and the loss of the rights of weavers or producers due to the entry of personal opinion and the failure to classify the effect of different parameters on the final point. The main purpose of this study is to collect various parameters affecting the wages of handmade carpet weavers in Iran. According to a collection of statistical data obtained from the country's most popular producers, the effects of different parameters were investigated through the Design of Experiment (DOE). Finally, the effect of each parameter was expressed as a percentage using Taguchi Approach (TA). The most important achievement of this research is that the obtained results can be used to prevent the loss of rights of the people by providing an appropriate formula and detail table

A comparative study on the fatigue life of the vehicle body spot welds using different numerical techniques: Inertia relief and Modal dynamic analyses

Among different parts of a vehicle, the body is the main load-bearing component and as a result, its durability is critical. Fatigue analyses are typically divided into different categories, the quasi-static methods and the dynamic methods. The aim of this paper was to compare the inertia relief and modal dynamic approaches for their formulation, accuracy and computation time. The chosen case study is the fatigue life of the vehicle body. By utilizing multi-body dynamics model and driving the vehicle on different standardized roads and by different velocities, the force and moment time histories which act on the body were calculated and later used by the finite element model for the stress analysis. Then, by using the structural stress method, the fatigue life of the vehicle spot welds were calculated and the results were compared for both quasi-static and dynamic approaches. The findings reveal that the modal dynamic method is almost 37 times more time-consuming than the inertia relief approach, but if accuracy is desired, it can be up to 96% more accurate. Also as predicted, at low frequency loading (less than 10% of the first nonzero frequency of the structure), there is no difference between the results of both methods

Common Failures in Hydraulic Kaplan Turbine Blades and Practical Solutions

Kaplan turbines, as one of the well-known hydraulic turbines, are generally utilized worldwide for low-head and high-flow conditions. Any failure in each of the turbine components can result in long-term downtime and high repair costs. In a particular case, if other parts are damaged due to the impact of the broken blades (e.g., the main shaft of the turbine), the whole power plant may be shut down. On the other hand, further research on the primary causes of failures in turbines can help improve the present failure evaluation methodologies in power plants. Hence, the main objective of this paper is to present the major causes of Kaplan turbine failures to prevent excessive damage to the equipment and provide practical solutions for them. In general, turbines are mainly subjected to both Internal Object Damage (IOD) and Foreign Object Damage (FOD). Accordingly, this paper presents a state-of-the-art review of Kaplan turbine failures related to material and physical defects, deficiencies in design, deficits in manufacturing and assembly processes, corrosion failures, fatigue failure, cavitation wear, types of cavitation in hydro turbines, hydro-abrasive problems, and hydro-erosion problems. Eventually, the authors have attempted to discuss practical hints (e.g., nanostructured coatings) to prevent damages and improve the performance of Kaplan turbines

Gene Expression Programming for Estimating Shear Strength of RC Squat Wall

The flanged, barbell, and rectangular squat reinforced concrete (RC) walls are broadly used in low-rise commercial and highway under and overpasses. The shear strength of squat walls is the major design consideration because of their smaller aspect ratio. Most of the current design codes or available published literature provide separate sets of shear capacity equations for flanged, barbell, and rectangular walls. Also, a substantial scatter exists in the predicted shear capacity due to a large discrepancy in the test data. Thus, this study aims to develop a single gene expression programming (GEP) expression that can be used for predicting the shear strength of these three cross-sectional shapes based on a dataset of 646 experiments. A total of thirteen influencing parameters are identified to contrive this efficient empirical compared to several shear capacity equations. Owing to the larger database, the proposed model shows better performance based on the database analysis results and compared with 9 available empirical models

Detection and Analysis of Corrosion and Contact Resistance Faults of TiN and CrN Coatings on 410 Stainless Steel as Bipolar Plates in PEM Fuel Cells

© 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).Bipolar Plates (BPPs) are the most crucial component of the Polymer Electrolyte Membrane (PEM) fuel cell system. To improve fuel cell stack performance and lifetime, corrosion resistance and Interfacial Contact Resistance (ICR) enhancement are two essential factors for metallic BPPs. One of the most effective methods to achieve this purpose is adding a thin solid film of conductive coating on the surfaces of these plates. In the present study, 410 Stainless Steel (SS) was selected as a metallic bipolar plate. The coating process was performed using titanium nitride and chromium nitride by the Cathodic Arc Evaporation (CAE) method. The main focus of this study was to select the best coating among CrN and TiN on the proposed alloy as a substrate of PEM fuel cells through the comparison technique with simultaneous consideration of corrosion resistance and ICR value. After verifying the TiN and CrN coating compound, the electrochemical assessment was conducted by the potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS) tests. The results of PDP show that all coated samples have an increase in the polarization resistance (R_p) values (ranging from 410.2 to 690.6 〖Ω·cm〗^2) compared to substrate 410 SS (230.1 〖Ω·cm〗^2 ). Corrosion rate values for bare 410 SS, CrN, and TiN coatings were measured as 0.096, 0.032, and 0.060 mpy, respectively. Facilities for X-ray Diffraction (XRD), Scanning Electron Microscope (SEM ), and Energy Dispersive X-ray Spectroscopy (EDXS) were utilized to perform phase, corrosion behavior, and microstructure analysis. Furthermore, ICR tests were performed on both coated and uncoated specimens. However, the ICR of the coated samples increased slightly compared to uncoated samples. Finally, according to corrosion performance results and ICR values, it can be concluded that the CrN layer is a suitable choice for deposition on 410 SS with the aim of being used in a BPP fuel cell system.Peer reviewedFinal Published versio