Mechanical Engineering eJournal最新文献

{"title":"Numerical Investigation of Thermohydraulic Performance of Triple Concentric-Tube Heat Exchanger with Longitudinal Fins","authors":"S. Hussain, U. A. Rajput, Q. B. Jamali, Q. A. Kazi, Sanaullah Mastoi","doi":"10.26782/jmcms.2021.08.00006","DOIUrl":"https://doi.org/10.26782/jmcms.2021.08.00006","url":null,"abstract":"In this work, a triple concentric-tube heat exchanger (TCTH) with or without the application of longitudinal fins is numerically studied concerning its thermohydraulic performance. The computational fluid dynamics (CFD) program, Ansys FLUENT was used to perform the simulations to study the heat transfer enhancement using three different types of hot fluids, i.e. Crude oil, engine oil, and light diesel oil. The validated numerical model was first employed to investigate the heat transfer performance of unfinned TCTHE. Then, longitudinal fins were modeled and investigated for comparative analyses of the thermohydraulic performances of both constructions. To predict the heat exchanger performance, key parameters such as heat flux and temperature field distribution were evaluated. Results revealed that modifying the heat exchanger with longitudinal fins on the tube surface dramatically improves its heat transfer rate. Therefore, this research is designed to keep in view further exploring the potential of longitudinal fins in obtaining an improved performance from these types of heat exchanger devices. The results showed that the crude oil fluid has high heat transfer rate than the other two fluids light diesel oil and engine oil. With the application of fins on the tubes’ surfaces, a significant heat transfer exchange among the fluids streams is observed.","PeriodicalId":404477,"journal":{"name":"Mechanical Engineering eJournal","volume":"94 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-08-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127910351","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Unified Moment-Based Modelling of Integrated Stochastic Processes","authors":"I. Kyriakou, R. Brignone, Gianluca Fusai","doi":"10.2139/ssrn.3893758","DOIUrl":"https://doi.org/10.2139/ssrn.3893758","url":null,"abstract":"In this paper we present a new general method for simulating integrals of stochastic processes. We focus on the nontrivial case of time integrals conditional on the state variable levels at the endpoints of a time interval, based on a moment-based probability distribution construction. We present different classes of models with important usages in finance, medicine, epidemiology, climatology, bioeconomics and physics. We highlight the benefits of our method and benchmark its performance against existing schemes.","PeriodicalId":404477,"journal":{"name":"Mechanical Engineering eJournal","volume":"134 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-07-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123594899","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Research of the Problem of Optimization and Development of a Calculation Method for Two-Stage Chain Drives Used in Heavy Industrial Vehicles in Conditions of Economic Efficiency","authors":"S. Aliyeva, J. Damirova, S. Abasova","doi":"10.21303/2461-4262.2021.001930","DOIUrl":"https://doi.org/10.21303/2461-4262.2021.001930","url":null,"abstract":"The article is dedicated to the problem of optimization of chain drives of the drilling unit. At present, increasing the power per machine to the optimal limits, reducing the material and energy consumption per unit capacity of the machine, as well as operating costs are considered topical issues. The machines that are designed and constructed to optimal limits must be very powerful and productive. The machines that are applied to perform drilling works in the oil and gas industry must be easy to operate, reliable and have ability to operate for a long time. When constructing such machines, their being lightweight, economical, as well as their preparation in a short time and at low cost should be taken into account in advance. In order to ensure the reliable operation of drilling rigs, it is more expedient to apply chain drive in their mechanical transmission. First of all, the application of chain drive in drilling units and hoisting mechanisms is considered. Then a calculation method was developed for the chain drives of the drilling unit used in deep exploration wells and the exploitation of wells, and, accordingly, the calculation of the chain drive was carried out. The chain drive consists of drive and driven sprockets and a chain that encompasses the sprockets and engages in their teeth. Chain drives with several driven sprockets are also used. In addition to the basic listed elements, chain drives include tensioners, lubricating device and guards. The chain consists of hinged links that provide mobility or “flexibility” of the chain. Chain drives can be performed in a wide range of parameters. The calculation took into account the quality of the material, the service life and durability of the chain drive construction","PeriodicalId":404477,"journal":{"name":"Mechanical Engineering eJournal","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-07-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121184258","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Improving the Wear Resistance of Heavy-Duty Elements in Tribomechanical Systems by a Combined Laser-Thermochemical Processing Method","authors":"M. Kindrachuk, O. Dukhota, Oleksandr Тіsov, E. Korbut, A. Yurchuk, V. Kharchenko, N. Naumenko","doi":"10.15587/1729-4061.2021.231595","DOIUrl":"https://doi.org/10.15587/1729-4061.2021.231595","url":null,"abstract":"This paper reports an analysis of the state of tribological support in the aviation industry. The use of surface strengthening technologies to extend the resource of friction node parts has been prioritized. Modern combined technologies of nitriding and laser treatment of steel surfaces have been reviewed. The mechanism has been elucidated that damages steel 30H2NVFA in the jackscrew actuator of transport aircraft flaps, which occurs due to insufficient surface hardness of the material after a generally accepted heat treatment. Auger electron spectroscopy analysis revealed a high concentration of oxygen on the surface: up to 41.4 at. %; the friction surface carbonation has been detected, especially significant at the surface of the pitting damage. A comprehensive technology of surface strengthening by nitriding+laser selective hardening has been suggested. The radiation power was 1 KW, the diameter of the focus spot was 2.5 mm, and the pitch between the focus spot centers was 2.5 mm. The total area of laser processing was 70 %. The steel temperature exceeded Ас3 and corresponded to the hardening temperature range. The depth of the nitrided layer increased to 400 µm, the maximum hardness on the surface was 1,350–1,380 HV0.2. The formation of a solid nitrided layer with a thickness of 200‒250 µm was observed, as well as a transition zone composed of column-shaped iron nitrides, which are introduced into the matrix material. As a result, a sharp gradient in the mechanical properties disappears. The tests confirmed that the wear resistance of the comprehensively treated surface was 2.1 times higher under dry friction conditions, and 4.5 times higher when lubricated with the \"Era\" grease (RF), compared with the 30H2NVFA steel nitrided by the conventional technology. In addition, there was no fragile destruction of the surface; the interaction with oxygen reduced significantly","PeriodicalId":404477,"journal":{"name":"Mechanical Engineering eJournal","volume":"5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133470086","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Development and Analysis of a New Approach for Simplified Determination of the Heating and the Cooling Loads of Livestock Buildings","authors":"K. Kostov, I. Ivanov, K. Atanasov","doi":"10.21303/2461-4262.2021.001310","DOIUrl":"https://doi.org/10.21303/2461-4262.2021.001310","url":null,"abstract":"Pig farming is a sector of animal husbandry, the development of which is great attention. The pork market occupies a large share in the trade in animal products. In the conditions of they do competition more efforts are made to improve the quality and reduce the cost of production. To achieve this goal, work is being done in several areas – development and expansion of the gene pool, improvement of the living environment in the premises for animal husbandry, reduction of energy costs. Along with the development of feeding technologies, it is necessary to create a suitable microclimate in the premises, in which the animals to realize their productive potential, which in turn is directly related to the use of heating and cooling systems. The design of these systems for both existing and new buildings is carried out according to generally accepted methodologies, which in turn require time for calculation and use of specialized software. The methodologies for determining the loads for heating and cooling of livestock buildings, in accordance with the current legislation in the Republic of Bulgaria, are compared with a new method proposed in this publication. The possibility to consider a livestock building from the point of view of the theory of heat exchange allows the use of the basic differential equations describing the dynamic interaction of the building with the environment. This description would be complete and complex to implement. Therefore, the method of dimensional analysis is used, which is based on generalized indicators, when fulfilling certain criteria of similarity. The aim of the new methodology is to shorten the design time and allow the rapid sizing of heating and cooling systems in livestock buildings. In developing the new methodology, the task was the proposed new approach to summarize the interaction of all physical parameters affecting the heat exchange between the building and the surrounding air, allowing to take into account changes in external (air temperature, wind speed, solar radiation intensity) and internal factors (heat given off by farm animals, lighting, process equipment and processes) affecting the heat exchange between the building and the ambient air.","PeriodicalId":404477,"journal":{"name":"Mechanical Engineering eJournal","volume":"17 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-03-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131625232","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Experimental Study on Role of Tool-Work Materials and Machining Conditions on Built-Up Edge Formation","authors":"Soumyajit Das, A. B. Chattopadhyay","doi":"10.2139/ssrn.3799073","DOIUrl":"https://doi.org/10.2139/ssrn.3799073","url":null,"abstract":"Built-up Edge is a well-known phenomenon in the manufacturing industry which probably a danger for the quality of the semi-finished or finished product. This unfavourable incident hampered surface finish and reduce the life f tool. During any machining operation such as turning; the tool and the performed blank stick together like welding action. Under high compressive stress, seizure keeps the material from sliding over the cutting tool rake face. The presence or non-appearance of a developed edge (BUE) is significant according to apparatus wear and surface completion. The potential systems and cycles of wear impacted by the various kinds of the built-up edge were talked about in our study. Metallographic examinations have indicated that recrystallization happens in the streamed layer. The progression of sub microscopic crystallites over the tool-face affects tool wear. From the experiment, the most positive cutting conditions, from the perspective of both wear and surface completion, happen without a developed edge. This work and moderate reports on the investigation of the BUE calculation of C30 steel machined at low rates with and without a cutting liquid.","PeriodicalId":404477,"journal":{"name":"Mechanical Engineering eJournal","volume":"53 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-03-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122699549","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Determination of the Dynamic Load of the Carrying Structure of the Hopper Wagon With the Actual Dimensions of Structural Elements","authors":"O. Fomin, A. Lovska, P. Skok, I. Rogovskii","doi":"10.15587/2706-5448.2021.225458","DOIUrl":"https://doi.org/10.15587/2706-5448.2021.225458","url":null,"abstract":"The object of research is the supporting structure of the pellet wagon with the actual dimensions of the supporting elements. One of the most problematic areas is the determination of the indicators of dynamics and strength of the supporting structure of the hopper wagon with the actual dimensions of the structural elements. \u0000A study of the dynamic loading of the supporting structure of the hopper wagon was carried out. At the same time, the actual dimensions of the structural elements were determined by means of field studies. Mathematical modeling of the dynamic loading of the load-carrying structure of a hopper wagon with the actual dimensions of structural elements was carried out by means of mathematical modeling. The studies were carried out in a flat coordinate system. The presence of three degrees of freedom of the supporting structure of the hopper wagon was taken into account: vibrations of twitching, bouncing and galloping. Differential equations were solved in the MathCad software package. In doing so, they were reduced to the Cauchy normal form, and then integrated using the Runge-Kutta method. It was found that the maximum value of the acceleration acting on the supporting structure of the hopper wagon is 38.5 m/s2, which is 2.7% higher than the acceleration of the supporting structure with nominal dimensions. \u0000Computer simulation of the dynamic loading of the supporting structure of the hopper wagon was carried out. The calculation was carried out using the finite element method in the SolidWorks Simulation (CosmosWorks) software package. It was found that the maximum accelerations are concentrated in the middle part of the supporting structure of the hopper wagon and amount to 36.2 m/s2. The F-criterion was used to verify the developed model. The calculations showed that the calculated value of the criterion is Fc = 1.09 and is less than the table value Ft = 3.29. The adequacy hypothesis is not rejected. \u0000The natural frequencies and vibration modes of the hopper wagon supporting structure were determined. It has been established that the values of natural vibration frequencies of the hopper wagon bearing structure with the actual dimensions of the structural elements are within the permissible limits. \u0000The research will contribute to the creation of relevant developments to extend the service life of wagons that have exhausted their standard resource, as well as to increase the efficiency of railway transport operation.","PeriodicalId":404477,"journal":{"name":"Mechanical Engineering eJournal","volume":"23 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-02-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121174889","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Optimization of Temperature Measurement on the Bus Drum Brake as a Basis for Developing Brake Fault Signals","authors":"R. Siregar, M. Adhitya, D. Sumarsono, N. Nazaruddin, G. Heryana, S. Prasetya, F. Zainuri","doi":"10.15587/1729-4061.2021.224907","DOIUrl":"https://doi.org/10.15587/1729-4061.2021.224907","url":null,"abstract":"Brake failure is always possible due to several factors that are difficult to control, such as a slight leak in the brake hose due to an impact or a rat bite. In the latest research, the development of a brake performance detection tool has been started, but how to detect a brake temperature more efficiently on the brakes of large vehicles has not been specified. Given the significant impact of losses due to brake failure and accidents that are still occurring, this research plays an important role. It must be completed immediately so that accident cases can be reduced. The object of this research is where the position of the maximum brake temperature occurs? How to measure brake temperature is more practical? What sensor is optimal in detecting a brake temperature? The research method is carried out in a systematic stage that ends with an experimental method. This study indicates that the maximum temperature is relative to the entire friction area between the canvas and the drum brake. The most efficient sensor placement is in the hole in the drum brake cover so that installation is more practical and the brakes are not disturbed by the sensor’s presence. The optimal sensor is a thermocouple sensor because it is more stable to vibrations and more resistant to mud disturbances than infrared sensors. When using a thermocouple sensor, the temperature detection results must be corrected. The correction factor can be made with the equation y=10.3670+1.3205x–0.0003x2, where y is the actual temperature displayed, and x is the input temperature from the thermocouple sensor’s initial detection. Accurate brake temperature detection results will be developed as a signal for detecting brake faults in real-time to avoid brake failure. Finally, the safety of public transportation can be improved","PeriodicalId":404477,"journal":{"name":"Mechanical Engineering eJournal","volume":"96 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-02-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122786275","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Measurement of Local Material Properties and Failure Analysis of Resistance Spot Welds of Advanced High-Strength Steel Sheets","authors":"Yunwu Ma, Akira Takikawa, J. Nakanishi, Kazuyoshi, Doira, Tetsuo Shimizu, Yongxin Lu, N. Ma","doi":"10.2139/ssrn.3772562","DOIUrl":"https://doi.org/10.2139/ssrn.3772562","url":null,"abstract":"Abstract Safety evaluation of resistance spot welds necessitates the accurate measurement of local constitutive properties. This study employed miniature mechanical tests to investigate the deformation and failure behaviors of nugget, heat affected zone (HAZ), and corona bond of resistance spot welded JSC980YL steel. A novel mini-peel test was developed to enable local fracture in HAZ for numerical inverse calibration of constitutive parameters. The fracture constants of weld zones calibrated using Cockcroft-Latham ductile failure criterion were incorporated in finite element models to predict the failure modes of spot welds in tensile-shear and cross-tension coupon tests. The result indicates that the ultimate tensile strengths of the nugget and the corona bond were 37.6% higher and 5.8% lower, respectively, than that of the base material. The nugget and HAZ exhibited ductile fracture, whereas the corona bond was brittle fracture with only 1.2% elongation. In the coupon tests, the increase of nugget diameter slowed down the damage accumulation rate in the nugget and accelerated that in the HAZ, resulting in the transition of failure mode from interfacial to pullout. The failure load of corona bond in coupon tests increased with the increase of nugget diameter while its contribution to the peak load decreased.","PeriodicalId":404477,"journal":{"name":"Mechanical Engineering eJournal","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122214312","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Multi-dimensional Lattices Design for Ultrahigh Specific Strength Metallic Structure in Additive Manufacturing","authors":"Qing Jin, Jae-hyun Yu, Kyungsik Ha, W. Lee, Sang-hu Park","doi":"10.2139/ssrn.3805235","DOIUrl":"https://doi.org/10.2139/ssrn.3805235","url":null,"abstract":"Abstract The importance of lightweight design of mechanical parts is increasing rapidly due to material and energy savings. As additive manufacturing (AM) technology advances, the lattice structures, which are extremely difficult shapes to fabricate using conventional manufacturing processes, has attracted great interest due to their intrinsic characteristics such as high strength and lightweight. We propose an effective global-local design approach of gradient lattice structures with the selection of a lattice type in a zone and optimizing its strut diameter considering the whole loading conditions of a mechanical part, in order to obtain higher specific strength than other corresponding designs. In this work, two basic types of a lattice named as BCC and OTC, was utilized to design diverse local lattices based on optimizing a strut-diameter. To evaluate the usefulness of this approach, we designed a three-point bending test specimen with topology-optimized multi-lattice wire model, and strut-based topometry optimization on the wire model. The experimental test results show that the optimized specimen had more than 67% higher strength per weight compared to other multi-lattice ones. Through this work, we believe that this method is a promising way to effectively design high strength mechanical parts with lightweight for use in high-valuable industrial applications.","PeriodicalId":404477,"journal":{"name":"Mechanical Engineering eJournal","volume":"24 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-01-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127649329","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}