The deterioration module (DM) is one of the four major modules necessary for any bridge management system (BMS). Environmental conditions, structural systems, bridge configuration, geographic location, and traffic data are some of the major factors that affect the development of deterioration modules. This emphasizes the need for the development of deterioration models that reflect the local conditions. In this article, some of the most important factors that could help in developing deterioration models in the Gulf Cooperation Council (GCC) were identified. The research was conducted in three phases; in the first phase, an extensive literature search was conducted to identify factors adopted in different deterioration models, and in phase two, the most relevant factors to the GCC environment were selected and these factors were further reduced based on input from local bridge experts. The result from the second phase is a list of factors identified by the experts. The identified list was utilized in phase three, which was focused on conducting a survey targeting bridge engineers to help identify the final selection and rank the factors according to their importance level. The results indicate that steel reinforcement protection, design load, chloride attack, type of defect, and age are the most important factors impacting bridge deterioration in the GCC. In addition, the time of rehabilitation; average daily truck traffic, ADTT; and average daily traffic, ADT, are the second most important factors. Factors with medium importance level are deck protection, services under the bridge, and inspection gap. The least important set of factors include temperature and wind load.
{"title":"Identifying the Factors Impacting Bridge Deterioration in the Gulf Cooperation Council","authors":"Rawan Al-Rashed, Akmal Abdelfatah, Sherif Yehia","doi":"10.3390/designs7060126","DOIUrl":"https://doi.org/10.3390/designs7060126","url":null,"abstract":"The deterioration module (DM) is one of the four major modules necessary for any bridge management system (BMS). Environmental conditions, structural systems, bridge configuration, geographic location, and traffic data are some of the major factors that affect the development of deterioration modules. This emphasizes the need for the development of deterioration models that reflect the local conditions. In this article, some of the most important factors that could help in developing deterioration models in the Gulf Cooperation Council (GCC) were identified. The research was conducted in three phases; in the first phase, an extensive literature search was conducted to identify factors adopted in different deterioration models, and in phase two, the most relevant factors to the GCC environment were selected and these factors were further reduced based on input from local bridge experts. The result from the second phase is a list of factors identified by the experts. The identified list was utilized in phase three, which was focused on conducting a survey targeting bridge engineers to help identify the final selection and rank the factors according to their importance level. The results indicate that steel reinforcement protection, design load, chloride attack, type of defect, and age are the most important factors impacting bridge deterioration in the GCC. In addition, the time of rehabilitation; average daily truck traffic, ADTT; and average daily traffic, ADT, are the second most important factors. Factors with medium importance level are deck protection, services under the bridge, and inspection gap. The least important set of factors include temperature and wind load.","PeriodicalId":53150,"journal":{"name":"Designs","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135679249","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}
Nasr A. Jabbar, Ihsan Y. Hussain, Oday I. Abdullah, M. N. Mohammed
The friction clutch design strongly depends upon the frictional heat generated between contact surfaces during slipping at the beginning of the engagement. Firstly, the frictional heat generated reduces the performance of the clutch system and then leads to premature failure for contacting surfaces in some cases. The experimental effort in this work included manufacturing friction facing from functionally graded material (FGM) (aluminum and silicon carbide) for the clutch system. For this purpose, a special test rig was developed to investigate the thermal behavior of FGM and compare it with other frictional materials. The Taguchi L9 orthogonal design was selected to analyze the effect of the three factors (rotational, speed, torque, and the type of the frictional material) with three levels on the surface temperature of the contacting surfaces. A three-dimensional finite element model was built to validate the experimental results where the difference between them did not exceed 5.2%. The experimental results showed that the temperatures grew with the disc radius. Furthermore, the surfaces of the pressure plates and the flywheel were affected by frictional heat flow, and this effect increased when increasing the sliding speed. The lowest temperatures occurred when using FGM, which was lower than the other materials by 10%. This study presented an integrated approach consisting of design, manufacturing, and testing to study the complex frictional materials’ effect on the clutch system’s tribological performance.
{"title":"An Experimental Investigation and Numerical Analysis of the Thermal Behavior of a Clutch System Using the Frictional Facing of Functionally Graded Materials","authors":"Nasr A. Jabbar, Ihsan Y. Hussain, Oday I. Abdullah, M. N. Mohammed","doi":"10.3390/designs7060125","DOIUrl":"https://doi.org/10.3390/designs7060125","url":null,"abstract":"The friction clutch design strongly depends upon the frictional heat generated between contact surfaces during slipping at the beginning of the engagement. Firstly, the frictional heat generated reduces the performance of the clutch system and then leads to premature failure for contacting surfaces in some cases. The experimental effort in this work included manufacturing friction facing from functionally graded material (FGM) (aluminum and silicon carbide) for the clutch system. For this purpose, a special test rig was developed to investigate the thermal behavior of FGM and compare it with other frictional materials. The Taguchi L9 orthogonal design was selected to analyze the effect of the three factors (rotational, speed, torque, and the type of the frictional material) with three levels on the surface temperature of the contacting surfaces. A three-dimensional finite element model was built to validate the experimental results where the difference between them did not exceed 5.2%. The experimental results showed that the temperatures grew with the disc radius. Furthermore, the surfaces of the pressure plates and the flywheel were affected by frictional heat flow, and this effect increased when increasing the sliding speed. The lowest temperatures occurred when using FGM, which was lower than the other materials by 10%. This study presented an integrated approach consisting of design, manufacturing, and testing to study the complex frictional materials’ effect on the clutch system’s tribological performance.","PeriodicalId":53150,"journal":{"name":"Designs","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136134998","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}
With the increase in global temperatures, a significant threat of overheating has been reported due to more frequent and severe heatwaves in the UK housing stock. This research analyzes dwellings’ physical attributes through overheating assessments and their adaptation for modern flats in London in the current (2022) and anticipated (2050) weather. According to preliminary research, Southeast and London in England, mid-terraced, and flats (especially built post 2012), among other archetypes, were discovered to be the most susceptible to overheating in the UK. This study employed a case study of a 2015 modern flat located in a high-risk overheating zone in London to understand the building’s overheating exposure. A range of Dynamic Thermal Simulations (DTS) was conducted using EnergyPlus with reference to case studies in order to assess the performance of passive cooling mitigation strategies (PCMS) on peak summer days (15 July) as well as during the summer against CIBSE Guide A and ASHARE 55. Reduced window area and LoE triple glazing were identified as excellent mitigation prototypes, in which solar gains through exterior glazing were reduced by 85.5% due to triple glazing. Zone sensible cooling was reduced by 52%, which minimized CO2 emissions. It was also identified that the final retrofit model passed CIBSE Guide A by achieving a temperature threshold of 20 °C to 25 °C during the summer months, whereas it failed to accomplish the ASHARE 55 criteria (20–24 °C). The outcome of this study justifies the necessity of tested PCMS and advises UK policymakers on how to foster resilient housing plans to overcome overheating issues.
{"title":"Mitigating Overheating Risks for Modern Flats in London Due to Climate Change","authors":"Mansi Jariwala, Ahmad Taki","doi":"10.3390/designs7060124","DOIUrl":"https://doi.org/10.3390/designs7060124","url":null,"abstract":"With the increase in global temperatures, a significant threat of overheating has been reported due to more frequent and severe heatwaves in the UK housing stock. This research analyzes dwellings’ physical attributes through overheating assessments and their adaptation for modern flats in London in the current (2022) and anticipated (2050) weather. According to preliminary research, Southeast and London in England, mid-terraced, and flats (especially built post 2012), among other archetypes, were discovered to be the most susceptible to overheating in the UK. This study employed a case study of a 2015 modern flat located in a high-risk overheating zone in London to understand the building’s overheating exposure. A range of Dynamic Thermal Simulations (DTS) was conducted using EnergyPlus with reference to case studies in order to assess the performance of passive cooling mitigation strategies (PCMS) on peak summer days (15 July) as well as during the summer against CIBSE Guide A and ASHARE 55. Reduced window area and LoE triple glazing were identified as excellent mitigation prototypes, in which solar gains through exterior glazing were reduced by 85.5% due to triple glazing. Zone sensible cooling was reduced by 52%, which minimized CO2 emissions. It was also identified that the final retrofit model passed CIBSE Guide A by achieving a temperature threshold of 20 °C to 25 °C during the summer months, whereas it failed to accomplish the ASHARE 55 criteria (20–24 °C). The outcome of this study justifies the necessity of tested PCMS and advises UK policymakers on how to foster resilient housing plans to overcome overheating issues.","PeriodicalId":53150,"journal":{"name":"Designs","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136231728","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}
Due to climate change, Egypt has recently suffered from recurring electricity crises. Despite efforts made to increase electricity production in Egypt, recently, in the summer months, the energy demand has increased at unprecedented rates, especially in the housing sector. Therefore, the government and homeowners should work together to improve the energy performance of residential buildings. This paper aimed to develop a decision-making tool that helps homeowners choose optimal energy retrofit measures that suit their priorities. The study began with the data-collection and case study selection. Then, the thermal evaluation of the base case for dwellings in the case study was conducted through simulation runs using the DesignBuilder v7.1 software. Then, the optimal envelope energy retrofitting measures were determined, followed by a retrofitting-measure scenario simulation process. Then, the payback periods were calculated for all scenarios, and the tool database was developed using an Excel spreadsheet. Finally, the user interface for envelope energy retrofitting measures for gated communities (EERMGCs) tool was designed by Visual Basic for Applications. EERMGCs, the tool developed in this paper, is a simple, multi-objective and interactive tool that provides the optimal envelope retrofit measures according to user priorities, either a specific budget, the shortest payback period, the lowest possible costs, or the highest energy saving rate. The outcome of this research is developing a framework that can be considered a basis for developing decision-making tools for gated community housing in Egypt.
由于气候变化，埃及最近遭受了反复出现的电力危机。尽管埃及努力增加电力生产，但最近，在夏季，能源需求以前所未有的速度增长，特别是在住房部门。因此，政府和业主应该共同努力，提高住宅建筑的能源性能。本文旨在开发一种决策工具，帮助房主选择适合其优先事项的最佳能源改造措施。研究从数据收集和案例研究选择开始。然后，通过使用DesignBuilder v7.1软件进行模拟运行，对案例研究中的住宅基本案例进行热评估。然后，确定了最优包络能量改造措施，并进行了改造措施情景模拟。然后，计算所有场景的投资回收期，并使用Excel电子表格开发工具数据库。最后，利用Visual Basic for Applications设计了封闭社区围护结构节能改造工具的用户界面。本文开发的EERMGCs工具是一种简单的、多目标的交互式工具，可根据用户优先级(特定预算、最短回收期、最低可能成本或最高节能率)提供最佳的包膜改造措施。这项研究的结果是开发一个框架，可被视为开发埃及封闭式社区住房决策工具的基础。
{"title":"Multi-Objective Decision-Making Tool for Envelope Energy Retrofitting Measures of Gated Community Housing in Egypt","authors":"Sarah Ahmad Algohary, Ayman Mahmoud, Manal Yehya","doi":"10.3390/designs7060123","DOIUrl":"https://doi.org/10.3390/designs7060123","url":null,"abstract":"Due to climate change, Egypt has recently suffered from recurring electricity crises. Despite efforts made to increase electricity production in Egypt, recently, in the summer months, the energy demand has increased at unprecedented rates, especially in the housing sector. Therefore, the government and homeowners should work together to improve the energy performance of residential buildings. This paper aimed to develop a decision-making tool that helps homeowners choose optimal energy retrofit measures that suit their priorities. The study began with the data-collection and case study selection. Then, the thermal evaluation of the base case for dwellings in the case study was conducted through simulation runs using the DesignBuilder v7.1 software. Then, the optimal envelope energy retrofitting measures were determined, followed by a retrofitting-measure scenario simulation process. Then, the payback periods were calculated for all scenarios, and the tool database was developed using an Excel spreadsheet. Finally, the user interface for envelope energy retrofitting measures for gated communities (EERMGCs) tool was designed by Visual Basic for Applications. EERMGCs, the tool developed in this paper, is a simple, multi-objective and interactive tool that provides the optimal envelope retrofit measures according to user priorities, either a specific budget, the shortest payback period, the lowest possible costs, or the highest energy saving rate. The outcome of this research is developing a framework that can be considered a basis for developing decision-making tools for gated community housing in Egypt.","PeriodicalId":53150,"journal":{"name":"Designs","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136262129","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}
Hazim U. Jamali, M. N. Mohammed, H. S. S. Aljibori, Muhsin Jaber Jweeg, Oday I. Abdullah
Robust and well-designed rotor-bearing systems ensure safe operation and a high level of reliability under severe operating conditions. A deviation in the shaft axis with respect to the bearing longitudinal axis represents one of the most unavoidable problems in bearing systems. This deviation results from installation errors, manufacturing errors, shaft deformation under heavy loads, bearing wear, and many other causes. Each of these deviation sources has its negative consequences on the designed characteristics of the system. This work deals with the geometrical design of a journal bearing using three forms of profiles (linear (n=1), quadratic n=2 and cubic (n=3) profiles) in order to enhance bearing performance despite the presence of the inevitable shaft deviation. In addition, a wide range of bearing profile parameters are considered in the analysis to optimize the bearing profile based on the use of the Taguchi method. A general form of shaft deviation is considered to account for both horizontal and vertical deviations. A numerical solution is obtained using the finite difference method. The results show that all three suggested forms of bearing profiles elevate the film thickness significantly and also reduce the friction coefficient, but with different effects on the maximum pressure values. The Taguchi method illustrates that the optimal geometrical design parameters are the quadratic profile and the modification of one-fifth of the bearing width from both sides at a height of just less than half the radial clearance (0.4 C) at the bearing edges. These values give the best combination of the considered main bearing characteristics: the minimum film thickness, coefficient of friction, and maximum pressure. The results show that the minimum film thickness is increased by 184%, the maximum pressure is reduced by 15.1% and the friction coefficient is decreased by 6.4% due to the use of the suggested design. The outcome of this work represents an important enhancement step for the rotor bearing performance to work safely with high reliability under severe shaft deviation levels. This can be implied at the design stage of the bearing, which requires prior knowledge about the operating conditions in order to have better estimation for the levels of shaft deviation.
{"title":"A Novel Optimization Strategy of Bearing Geometry with a Length to Diameter Ratio of 1.25 under Severe Operating Conditions Using Taguchi Method","authors":"Hazim U. Jamali, M. N. Mohammed, H. S. S. Aljibori, Muhsin Jaber Jweeg, Oday I. Abdullah","doi":"10.3390/designs7060121","DOIUrl":"https://doi.org/10.3390/designs7060121","url":null,"abstract":"Robust and well-designed rotor-bearing systems ensure safe operation and a high level of reliability under severe operating conditions. A deviation in the shaft axis with respect to the bearing longitudinal axis represents one of the most unavoidable problems in bearing systems. This deviation results from installation errors, manufacturing errors, shaft deformation under heavy loads, bearing wear, and many other causes. Each of these deviation sources has its negative consequences on the designed characteristics of the system. This work deals with the geometrical design of a journal bearing using three forms of profiles (linear (n=1), quadratic n=2 and cubic (n=3) profiles) in order to enhance bearing performance despite the presence of the inevitable shaft deviation. In addition, a wide range of bearing profile parameters are considered in the analysis to optimize the bearing profile based on the use of the Taguchi method. A general form of shaft deviation is considered to account for both horizontal and vertical deviations. A numerical solution is obtained using the finite difference method. The results show that all three suggested forms of bearing profiles elevate the film thickness significantly and also reduce the friction coefficient, but with different effects on the maximum pressure values. The Taguchi method illustrates that the optimal geometrical design parameters are the quadratic profile and the modification of one-fifth of the bearing width from both sides at a height of just less than half the radial clearance (0.4 C) at the bearing edges. These values give the best combination of the considered main bearing characteristics: the minimum film thickness, coefficient of friction, and maximum pressure. The results show that the minimum film thickness is increased by 184%, the maximum pressure is reduced by 15.1% and the friction coefficient is decreased by 6.4% due to the use of the suggested design. The outcome of this work represents an important enhancement step for the rotor bearing performance to work safely with high reliability under severe shaft deviation levels. This can be implied at the design stage of the bearing, which requires prior knowledge about the operating conditions in order to have better estimation for the levels of shaft deviation.","PeriodicalId":53150,"journal":{"name":"Designs","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134908482","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}
Although free vibrations of thin-walled cylinders have been extensively addressed in the relevant literature, finding a good balance between accuracy and simplicity of the procedures used for natural frequency assessment is still an open issue. This paper proposes a novel approach with a high potential for practical application for rapid esteem of natural frequencies of thin-walled cylinders under different boundary conditions. Starting from Donnell–Mushtari’s shell theory, the differential problem is simplified by using the principle of virtual work and introducing the flexural waveforms of a beam as constrained as the cylinder. Hence, the formulation is reduced to the eigenvalue problem of an equivalent 3 × 3 dynamic matrix, which depends on the cylinder geometry, material, and boundary conditions. Several comparisons with experimental, numerical, and analytical approaches are presented to prove model reliability and practical interest. An excellent balance between fast usability and accuracy is achieved. The user-friendliness of the model makes it suitable to be implemented during the design stage without requiring any deep knowledge of the topic.
{"title":"A Dynamic Matrix for the Study of Free Vibrations of Thin Circular Cylindrical Shells under Different Boundary Conditions","authors":"Marco Cammalleri, Antonella Castellano","doi":"10.3390/designs7060122","DOIUrl":"https://doi.org/10.3390/designs7060122","url":null,"abstract":"Although free vibrations of thin-walled cylinders have been extensively addressed in the relevant literature, finding a good balance between accuracy and simplicity of the procedures used for natural frequency assessment is still an open issue. This paper proposes a novel approach with a high potential for practical application for rapid esteem of natural frequencies of thin-walled cylinders under different boundary conditions. Starting from Donnell–Mushtari’s shell theory, the differential problem is simplified by using the principle of virtual work and introducing the flexural waveforms of a beam as constrained as the cylinder. Hence, the formulation is reduced to the eigenvalue problem of an equivalent 3 × 3 dynamic matrix, which depends on the cylinder geometry, material, and boundary conditions. Several comparisons with experimental, numerical, and analytical approaches are presented to prove model reliability and practical interest. An excellent balance between fast usability and accuracy is achieved. The user-friendliness of the model makes it suitable to be implemented during the design stage without requiring any deep knowledge of the topic.","PeriodicalId":53150,"journal":{"name":"Designs","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134905562","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}
Manuel de Jesús Gurrola Arrieta, Ruxandra Mihaela Botez
In the published paper [...]
在发表的论文中[…]
{"title":"Correction: Gurrola Arrieta, M.d.J.; Botez, R.M. Improved Local Scale Generic Cycle Model for Aerothermodynamic Simulations of Gas Turbine Engines for Propulsion. Designs 2022, 6, 91","authors":"Manuel de Jesús Gurrola Arrieta, Ruxandra Mihaela Botez","doi":"10.3390/designs7060120","DOIUrl":"https://doi.org/10.3390/designs7060120","url":null,"abstract":"In the published paper [...]","PeriodicalId":53150,"journal":{"name":"Designs","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135267254","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}
Kitesa Akewaq Irena, Hirpa G. Lemu, Yahiya Ahmed Kedir
Mechanical couplings in engineering usually use interference fits to connect the shaft and hub. A railway wheel axle is a press fit that is connected by interference and can be subjected to bending stress. In loaded press fits, a high concentration of contact stresses can be generated in the area of the axle-fillet beam, which in most cases leads to the failure of the axle due to fatigue and fretting fatigues. Therefore, it is crucial to determine the ability of the press-fitted joints to provide sufficient frictional resistance that can withstand the loads and torques by evaluating the safety factor, especially when the mechanical or structural system is loaded. In this paper, the contact pressure and stress distribution along the radius of the wheel axle are studied using the analytical calculation of Lame’s equation, and the numerical method used is by ANSYS software. It was found that interference fits have a great influence on the connection strength of interference fits, which are directly related to the contact pressure. Increasing the interference increases the contact pressure, which allows higher torque and load capacity to be transmitted. The finite element analysis showed good agreement for the highest interference value of 230 µm with a relative error of 1.4%, while this error increased to the maximum relative error of 14.33% for a minimum interference of 100 µm.
{"title":"Effect of Interference Size on Contact Pressure Distribution of Railway Wheel Axle Press Fitting","authors":"Kitesa Akewaq Irena, Hirpa G. Lemu, Yahiya Ahmed Kedir","doi":"10.3390/designs7050119","DOIUrl":"https://doi.org/10.3390/designs7050119","url":null,"abstract":"Mechanical couplings in engineering usually use interference fits to connect the shaft and hub. A railway wheel axle is a press fit that is connected by interference and can be subjected to bending stress. In loaded press fits, a high concentration of contact stresses can be generated in the area of the axle-fillet beam, which in most cases leads to the failure of the axle due to fatigue and fretting fatigues. Therefore, it is crucial to determine the ability of the press-fitted joints to provide sufficient frictional resistance that can withstand the loads and torques by evaluating the safety factor, especially when the mechanical or structural system is loaded. In this paper, the contact pressure and stress distribution along the radius of the wheel axle are studied using the analytical calculation of Lame’s equation, and the numerical method used is by ANSYS software. It was found that interference fits have a great influence on the connection strength of interference fits, which are directly related to the contact pressure. Increasing the interference increases the contact pressure, which allows higher torque and load capacity to be transmitted. The finite element analysis showed good agreement for the highest interference value of 230 µm with a relative error of 1.4%, while this error increased to the maximum relative error of 14.33% for a minimum interference of 100 µm.","PeriodicalId":53150,"journal":{"name":"Designs","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135461395","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}
Cristian Abad-Coronel, Johanna Córdova, Andrea Merchán, Jaime Larriva, Ariana Bravo, Bryam Bernal, Cesar A. Paltán, Jorge I. Fajardo
The aim of this study was to evaluate and compare the fracture resistance of a temporary three-unit fixed dental prosthesis (FDP) made of a new polymeric material obtained by an additive technique (3DPP) using a computer-aided design and manufacturing (CAD/CAM) system, comparing the prosthesis to the respective outcomes of temporary polymethylmethacrylate (PMMA) FDPs obtained by a subtractive technique (milling). Methods: Three-unit FDPs were 3D printed using a polymeric material (n = 20) or milled using polymethylmethacrylate (n = 20). After thermocycling at 5000 cycles at extreme temperatures of 5 °C and 55 °C in distilled water, each specimen was subjected to a compression test on a universal testing machine at a rate of 0.5 mm/min until failure occurred, recording the value in newtons (N). Results: There were statistically significant differences (p-value < 0.005) between the PMMA material (2104.7 N; SD = 178.97 N) and 3DPP (1000.8 N; SD = 196.4 N). Conclusions: The fracture resistance of the PDFs manufactured from milled PMMA showed higher values for fracture resistance. However, the resistance of the 3DPP showed acceptable values under mechanical load; this notable advance in the resistance of printed materials consolidates them as an important alternative to use in interim indirect restorations.
{"title":"Comparative Analysis of the Fracture Resistance of a Polymeric Material for 3D Printing and a Milled Polymethylmethacrylate Material as Interim Material for Fixed Partial Dentures: New Material Updated","authors":"Cristian Abad-Coronel, Johanna Córdova, Andrea Merchán, Jaime Larriva, Ariana Bravo, Bryam Bernal, Cesar A. Paltán, Jorge I. Fajardo","doi":"10.3390/designs7050118","DOIUrl":"https://doi.org/10.3390/designs7050118","url":null,"abstract":"The aim of this study was to evaluate and compare the fracture resistance of a temporary three-unit fixed dental prosthesis (FDP) made of a new polymeric material obtained by an additive technique (3DPP) using a computer-aided design and manufacturing (CAD/CAM) system, comparing the prosthesis to the respective outcomes of temporary polymethylmethacrylate (PMMA) FDPs obtained by a subtractive technique (milling). Methods: Three-unit FDPs were 3D printed using a polymeric material (n = 20) or milled using polymethylmethacrylate (n = 20). After thermocycling at 5000 cycles at extreme temperatures of 5 °C and 55 °C in distilled water, each specimen was subjected to a compression test on a universal testing machine at a rate of 0.5 mm/min until failure occurred, recording the value in newtons (N). Results: There were statistically significant differences (p-value < 0.005) between the PMMA material (2104.7 N; SD = 178.97 N) and 3DPP (1000.8 N; SD = 196.4 N). Conclusions: The fracture resistance of the PDFs manufactured from milled PMMA showed higher values for fracture resistance. However, the resistance of the 3DPP showed acceptable values under mechanical load; this notable advance in the resistance of printed materials consolidates them as an important alternative to use in interim indirect restorations.","PeriodicalId":53150,"journal":{"name":"Designs","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135858876","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}
Alan Huarca Pulcha, Alain Jorge Espinoza Vigil, Julian Booker
Globally, most bridges fail due to hydrological causes such as scouring or flooding. Therefore, using a hydrological approach, this study proposes a methodology that contributes to prioritizing the intervention of bridges to prevent their collapse. Through an exhaustive literature review, an evaluation matrix subdivided into four dimensions was developed and a total of 18 evaluation parameters were considered, distributed as follows: four environmental, six technical, four social, and four economic. This matrix was applied to eight bridges with a history of hydrological problems in the same river and validated through semi-structured interviews with specialists. Data were collected through field visits, journalistic information, a review of the gauged basin’s historical hydrological flow rates, and consultations with the population. Modeling was then conducted, which considered the influence of gullies that discharge additional flow using HEC-HMS and HEC-RAS, before being calibrated. The application of the matrix, which is an optimal tool for prioritizing bridge interventions, revealed that five bridges have a high vulnerability with scores between 3 and 3.56, and three bridges have a medium vulnerability with scores between 2.75 and 2.94. The hydrological multidimensional approach, which can be adapted for similar studies, contributes to a better decision-making process for important infrastructure interventions such as riverine bridges.
{"title":"Prioritizing Riverine Bridge Interventions: A Hydrological and Multidimensional Approach","authors":"Alan Huarca Pulcha, Alain Jorge Espinoza Vigil, Julian Booker","doi":"10.3390/designs7050117","DOIUrl":"https://doi.org/10.3390/designs7050117","url":null,"abstract":"Globally, most bridges fail due to hydrological causes such as scouring or flooding. Therefore, using a hydrological approach, this study proposes a methodology that contributes to prioritizing the intervention of bridges to prevent their collapse. Through an exhaustive literature review, an evaluation matrix subdivided into four dimensions was developed and a total of 18 evaluation parameters were considered, distributed as follows: four environmental, six technical, four social, and four economic. This matrix was applied to eight bridges with a history of hydrological problems in the same river and validated through semi-structured interviews with specialists. Data were collected through field visits, journalistic information, a review of the gauged basin’s historical hydrological flow rates, and consultations with the population. Modeling was then conducted, which considered the influence of gullies that discharge additional flow using HEC-HMS and HEC-RAS, before being calibrated. The application of the matrix, which is an optimal tool for prioritizing bridge interventions, revealed that five bridges have a high vulnerability with scores between 3 and 3.56, and three bridges have a medium vulnerability with scores between 2.75 and 2.94. The hydrological multidimensional approach, which can be adapted for similar studies, contributes to a better decision-making process for important infrastructure interventions such as riverine bridges.","PeriodicalId":53150,"journal":{"name":"Designs","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136013581","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}
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