Udayanto Dwi Atmojo, Walter Quadrini, Valentina Nucera, P. Pedrazzoli, Michele Fiorello
The recent industrial trends helped manufacturing companies to digitalise their shopfloor and to exploit the functionalities of new data-based technologies. However, small and medium manufacturing enterprises, due to their size, faced several barriers in embodying the knowhow to manage these new technologies. For this reason, LIFT Europe, a consortium made by eleven universities and one competence centre, has been constituted, matching the companies needs and the expertise of its partners in creating a set of courses targeted to fill this knowledge gap.
{"title":"Creating a Methodology to Train Manufacturing SMEs: The Lift Europe Case","authors":"Udayanto Dwi Atmojo, Walter Quadrini, Valentina Nucera, P. Pedrazzoli, Michele Fiorello","doi":"10.2139/ssrn.3862463","DOIUrl":"https://doi.org/10.2139/ssrn.3862463","url":null,"abstract":"The recent industrial trends helped manufacturing companies to digitalise their shopfloor and to exploit the functionalities of new data-based technologies. However, small and medium manufacturing enterprises, due to their size, faced several barriers in embodying the knowhow to manage these new technologies. For this reason, LIFT Europe, a consortium made by eleven universities and one competence centre, has been constituted, matching the companies needs and the expertise of its partners in creating a set of courses targeted to fill this knowledge gap.","PeriodicalId":18300,"journal":{"name":"MatSciRN: Other Materials Processing & Manufacturing (Topic)","volume":"37 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-06-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82510429","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}
Atacan Ketenci, Matthias Eder, M. Ritter, C. Ramsauer
Caused by the constantly rising energy prices and the demand for green products, the manufacturing industry has to increasingly deal with the topic of energy optimization. Thus, the focus is shifting to the improvement of production facilities in order to minimize resource consumption. When planning a more energy efficient production, it is advisable to set up a continuous monitoring system on the existing equipment to get an insight into the prevailing energy consumption. Based on this, optimization potentials can be identified. Different possibilities for increasing energy efficiency already exist, including e.g. the use of more efficient equipment or the optimal use of the facility. However, realistic assessments of saving potentials are a big challenge. In this paper, a virtual model of a learning factory is created to assess a realistic energy consumption profile. Using currently measured energy data and possible investment activities, scenarios for energy optimization in the assembly line are generated. By evaluating the scenarios using the virtual model, realistic saving potentials can be determined and evaluated, enabling investment planning to be strategically improved through the consideration of energy efficiency.
{"title":"Scenario-based Simulation for Energy Optimization in Learning Factory Environments","authors":"Atacan Ketenci, Matthias Eder, M. Ritter, C. Ramsauer","doi":"10.2139/ssrn.3858326","DOIUrl":"https://doi.org/10.2139/ssrn.3858326","url":null,"abstract":"Caused by the constantly rising energy prices and the demand for green products, the manufacturing industry has to increasingly deal with the topic of energy optimization. Thus, the focus is shifting to the improvement of production facilities in order to minimize resource consumption. When planning a more energy efficient production, it is advisable to set up a continuous monitoring system on the existing equipment to get an insight into the prevailing energy consumption. Based on this, optimization potentials can be identified. Different possibilities for increasing energy efficiency already exist, including e.g. the use of more efficient equipment or the optimal use of the facility. However, realistic assessments of saving potentials are a big challenge. In this paper, a virtual model of a learning factory is created to assess a realistic energy consumption profile. Using currently measured energy data and possible investment activities, scenarios for energy optimization in the assembly line are generated. By evaluating the scenarios using the virtual model, realistic saving potentials can be determined and evaluated, enabling investment planning to be strategically improved through the consideration of energy efficiency.","PeriodicalId":18300,"journal":{"name":"MatSciRN: Other Materials Processing & Manufacturing (Topic)","volume":"11 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-06-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73735162","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}
The lack of a thorough understanding of Al-Al3Sc eutectic growth motivates the present work. We observed a rod-typed Al 3 Sc eutectic phase existing prevalently in an as-cast Al-2 wt. % Sc alloy that solidified via both slow cooling in air (~1 oC·s−1) and rapid cooling in a wedge-shaped copper mold (up to ~3000 oC·s−1), different from reported results. Al-Al3Sc eutectic dendrites were identified within a narrow region near the edge of the wedge. The eutectic dendrites have an equiaxed dendritic contour and a rod eutectic structure inside. The condition for the growth of the eutectic dendrites was assessed by using appropriate analytical models. It was revealed that an interface undercooling of 48.2 oC is required to form the eutectic dendrites, or to enter the coupled zone of the Al-Al3Sc phase diagram. A phenomenon of scientific interest is that when crystallizing under a near-equilibrium condition, the eutectic Al3Sc phase formed a non-faceted morphology, in contradiction to its faceted nature. Based on the competitive growth criterion, we deduced that the non-faceting of the eutectic Al3Sc phase essentially reduces the interface undercooling for the resultant regular eutectic, in comparison to an otherwise irregular eutectic that contains a faceted eutectic Al3Sc phase.
{"title":"Rod Eutectic Growth of Al-Al 3Sc in Al-2 Wt. % Sc Undercooled Melt","authors":"Aoke Jiang, Siming Ma, Xiaoming Wang","doi":"10.2139/ssrn.3820195","DOIUrl":"https://doi.org/10.2139/ssrn.3820195","url":null,"abstract":"The lack of a thorough understanding of Al-Al3Sc eutectic growth motivates the present work. We observed a rod-typed Al 3 Sc eutectic phase existing prevalently in an as-cast Al-2 wt. % Sc alloy that solidified via both slow cooling in air (~1 oC·s−1) and rapid cooling in a wedge-shaped copper mold (up to ~3000 oC·s−1), different from reported results. Al-Al3Sc eutectic dendrites were identified within a narrow region near the edge of the wedge. The eutectic dendrites have an equiaxed dendritic contour and a rod eutectic structure inside. The condition for the growth of the eutectic dendrites was assessed by using appropriate analytical models. It was revealed that an interface undercooling of 48.2 oC is required to form the eutectic dendrites, or to enter the coupled zone of the Al-Al3Sc phase diagram. A phenomenon of scientific interest is that when crystallizing under a near-equilibrium condition, the eutectic Al3Sc phase formed a non-faceted morphology, in contradiction to its faceted nature. Based on the competitive growth criterion, we deduced that the non-faceting of the eutectic Al3Sc phase essentially reduces the interface undercooling for the resultant regular eutectic, in comparison to an otherwise irregular eutectic that contains a faceted eutectic Al3Sc phase.","PeriodicalId":18300,"journal":{"name":"MatSciRN: Other Materials Processing & Manufacturing (Topic)","volume":"76 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-04-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86509622","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}
Abstract Rechargeable aqueous zinc-ion batteries (ZIBs) have been receiving much attention because they are cheap, safe, and environment-friendly. However, their application is bottlenecked by limitation in high-capacity cathode and types of materials to achieve satisfactory cyclability. Therefore, developing new cathode materials for rechargeable zinc-ion batteries is essential. Herein, we report promising ZIBs based on metal-organic framework-derived 2-methylimidazole zinc salt (ZIF-8)/Mn2O3 nanocomposites as cathode and zinc as the anode. ZnMn2O4/Mn2O3 bi-component nanorods were synthesized by annealing ZIF-8/MnO2 precursors, which showed a reversible discharge capacity of 230 mAh g–1 at 100 mA g–1 after 120 cycles and a high capacity of 80 mAh g–1 at a large current density of 1000 mA g–1. The superior zinc storage performance is attributed to the synergistic effect between ZnMn2O4 and Mn2O3.
摘要可充水锌离子电池(zib)因其廉价、安全、环保等优点而备受关注。然而，它们的应用受到高容量阴极和材料类型的限制，以达到令人满意的可循环性。因此，开发可充电锌离子电池的新型正极材料至关重要。在此，我们报道了基于金属-有机框架衍生的2-甲基咪唑锌盐(ZIF-8)/Mn2O3纳米复合材料作为阴极和锌作为阳极的有前途的ZIBs。通过对ZIF-8/MnO2前驱体的退火，合成了ZnMn2O4/Mn2O3双组分纳米棒，该纳米棒在100 mA g-1下循环120次后具有230 mAh g-1的可逆放电容量，在1000 mA g-1的大电流密度下具有80 mAh g-1的高容量。ZnMn2O4和Mn2O3之间的协同作用是其优异的储锌性能的主要原因。
{"title":"Zinc Manganate/Manganic Oxide Bi-Component Nanorod as Excellent Cathode for Zinc-Ion Battery","authors":"Shiyue Ma, Si-Xu Wang, Dong-Shuai Li, Weiliang Liu, M. Ren, Fanyuan Kong, Shoujuan Wang, Yongjao Xia","doi":"10.2139/ssrn.3674206","DOIUrl":"https://doi.org/10.2139/ssrn.3674206","url":null,"abstract":"Abstract Rechargeable aqueous zinc-ion batteries (ZIBs) have been receiving much attention because they are cheap, safe, and environment-friendly. However, their application is bottlenecked by limitation in high-capacity cathode and types of materials to achieve satisfactory cyclability. Therefore, developing new cathode materials for rechargeable zinc-ion batteries is essential. Herein, we report promising ZIBs based on metal-organic framework-derived 2-methylimidazole zinc salt (ZIF-8)/Mn2O3 nanocomposites as cathode and zinc as the anode. ZnMn2O4/Mn2O3 bi-component nanorods were synthesized by annealing ZIF-8/MnO2 precursors, which showed a reversible discharge capacity of 230 mAh g–1 at 100 mA g–1 after 120 cycles and a high capacity of 80 mAh g–1 at a large current density of 1000 mA g–1. The superior zinc storage performance is attributed to the synergistic effect between ZnMn2O4 and Mn2O3.","PeriodicalId":18300,"journal":{"name":"MatSciRN: Other Materials Processing & Manufacturing (Topic)","volume":"64 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76199400","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}
Pub Date : 2021-02-19DOI: 10.15587/1729-4061.2021.224912
Sergiy Gnitko, I. Vasyliev, S. Popov
This paper addresses the issue of difficulties in servicing the brake pipe connectors for passenger cars, the service life of which exceeds 8‒10 years, which is associated with the deteriorated loosening of connectors. The existing ways to loosen the connectors of brake pipes have been investigated, especially those whose dismantling is complicated due to the corrosion and contamination of mated surfaces as a result of their wetting when driving a car. A conventional structure of the connector has been analyzed, which is installed in that place of the car that is the most unprotected from moisture and dirt – on the brake cylinder. The conditions that do not contribute to its failure-free loosening have been examined. The design of a specialized split clamping ring wrench has been considered, which can transmit the greatest value of the torque to the connector when loosening it; sometimes, however, its predefined value would not suffice. A computer-based finite-element simulation was employed to derive the models of the deformation state for the node «connector ‒ wrench». Based on the analysis of the models of different deformation state of a specialized split clamping ring wrench, the required profile of the geometrically balanced locked hexagonal profile of the wrench was defined. The analysis of the efficiency of the tightening and loosening level is determined by comparing the numerical values of the torque, which is applied to the connectors of the brake pipes. The torque values are measured by a specially devised technique. The introduction of the developed measurement technique makes it possible to compare the efficiency of wrenches of different designs by analyzing the maximum values of torques, which the wrenches can transmit to the connectors. Taking into consideration the identified shortcomings in the structure of the brake pipe connectors, the shape of the connector has been designed that is free from the specified drawbacks. The new structure provides for the possibility of using a conventional carob wrench for loosening when the mated surfaces are exposed to contamination and corrosion
{"title":"Designing an Improved Structure of the Tool for Repairing the Brake Pipe Connectors in Vehicles","authors":"Sergiy Gnitko, I. Vasyliev, S. Popov","doi":"10.15587/1729-4061.2021.224912","DOIUrl":"https://doi.org/10.15587/1729-4061.2021.224912","url":null,"abstract":"This paper addresses the issue of difficulties in servicing the brake pipe connectors for passenger cars, the service life of which exceeds 8‒10 years, which is associated with the deteriorated loosening of connectors. The existing ways to loosen the connectors of brake pipes have been investigated, especially those whose dismantling is complicated due to the corrosion and contamination of mated surfaces as a result of their wetting when driving a car. A conventional structure of the connector has been analyzed, which is installed in that place of the car that is the most unprotected from moisture and dirt – on the brake cylinder. The conditions that do not contribute to its failure-free loosening have been examined. The design of a specialized split clamping ring wrench has been considered, which can transmit the greatest value of the torque to the connector when loosening it; sometimes, however, its predefined value would not suffice. A computer-based finite-element simulation was employed to derive the models of the deformation state for the node «connector ‒ wrench». Based on the analysis of the models of different deformation state of a specialized split clamping ring wrench, the required profile of the geometrically balanced locked hexagonal profile of the wrench was defined. The analysis of the efficiency of the tightening and loosening level is determined by comparing the numerical values of the torque, which is applied to the connectors of the brake pipes. The torque values are measured by a specially devised technique. The introduction of the developed measurement technique makes it possible to compare the efficiency of wrenches of different designs by analyzing the maximum values of torques, which the wrenches can transmit to the connectors. Taking into consideration the identified shortcomings in the structure of the brake pipe connectors, the shape of the connector has been designed that is free from the specified drawbacks. The new structure provides for the possibility of using a conventional carob wrench for loosening when the mated surfaces are exposed to contamination and corrosion","PeriodicalId":18300,"journal":{"name":"MatSciRN: Other Materials Processing & Manufacturing (Topic)","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-02-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90658507","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}
A. Elinwa, Mustapha Maibulangu, Isaiah Ogbo, A. Salisu
The density and mechanical strengths of concrete are important properties in the study of concrete structures. An experimental study was mounted to study these concrete properties and the effects of using sawdust ash (SDA) and gum Arabic (GA). In studying these effects four concrete mixtures designated as C/00SDA:GA-00, C/00-SDA:GA-0.5, C/10-SDA:GA-0.5, and C/30-SDA:GA-0.5, respectively. The Mix with C/00-SDA:GA-00, is the control (containing zero percent SDA and GA), with a mix proportion of 1: 2.24: 2.71. The cement content was 370 kg/m3 with a water-cement ratio of 0.5. The other mixes contain either 0.5 % GA (only), or 0.5 % GA with 10 % SDA or 30 % SDA replacement by wt. % of cement, as the case may be. The results showed that the addition of GA and SDA to concrete have various degrees of effects on the concrete parameters. The effect of 0.5 % GA decreased the density of the cube sample but increased the beam and the cylinder samples. On the other hand, the mechanical strengths were increased for all the samples. Using GA with SDA reduced the mechanical strengths of all the concrete samples. However, Ca (OH) 2 was reduced by 54 % by the addition of 10 % SDA and 12 % by 30 % SDA addition by wt. % of cement. The empirical models developed on the density and mechanical strengths showed good predictive values with relative predictive errors (RPE) ranging from 0.00% to 0.045 %.
{"title":"Density and Mechanical Strength of Gum Arabic-Sawdust Ash Concrete.","authors":"A. Elinwa, Mustapha Maibulangu, Isaiah Ogbo, A. Salisu","doi":"10.2139/ssrn.3780727","DOIUrl":"https://doi.org/10.2139/ssrn.3780727","url":null,"abstract":"The density and mechanical strengths of concrete are important properties in the study of concrete structures. An experimental study was mounted to study these concrete properties and the effects of using sawdust ash (SDA) and gum Arabic (GA). In studying these effects four concrete mixtures designated as C/00SDA:GA-00, C/00-SDA:GA-0.5, C/10-SDA:GA-0.5, and C/30-SDA:GA-0.5, respectively. The Mix with C/00-SDA:GA-00, is the control (containing zero percent SDA and GA), with a mix proportion of 1: 2.24: 2.71. The cement content was 370 kg/m3 with a water-cement ratio of 0.5. The other mixes contain either 0.5 % GA (only), or 0.5 % GA with 10 % SDA or 30 % SDA replacement by wt. % of cement, as the case may be. The results showed that the addition of GA and SDA to concrete have various degrees of effects on the concrete parameters. The effect of 0.5 % GA decreased the density of the cube sample but increased the beam and the cylinder samples. On the other hand, the mechanical strengths were increased for all the samples. Using GA with SDA reduced the mechanical strengths of all the concrete samples. However, Ca (OH) 2 was reduced by 54 % by the addition of 10 % SDA and 12 % by 30 % SDA addition by wt. % of cement. The empirical models developed on the density and mechanical strengths showed good predictive values with relative predictive errors (RPE) ranging from 0.00% to 0.045 %.","PeriodicalId":18300,"journal":{"name":"MatSciRN: Other Materials Processing & Manufacturing (Topic)","volume":"83 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-02-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80914723","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}
Honglin Zhang, Gang Zhou, Ming-yue Sun, Bin Xu, Dianzhong Li, Yiyi Li
Interfacial oxides can be removed by thermodynamic decomposition in the metallic solid-state bonding. Despite adequate observations, the dissolution behavior is not yet well understood. Based on the hot-compression bonding experiments of a Fe-Cr-Ni stainless steel, first-principles calculations are adopted to reveal the diffusion of oxygen in the Cr2O3/FCC-Fe heterostructure to identify the dissolution process. The results show that the heterogeneous interface favors the formation of oxygen vacancies, and the oxygen prefers to diffuse through the facet of coordination tetrahedron of Cr atoms than their bridge-site. The dissolution of the oxides is dominated by the diffusion of dissociated oxygen to the interface due to its high activation energy of 720 kJ·mol-1, while the heterogeneous interface provides a favorable transport channel to allow the oxygen diffuse into iron matrix.
{"title":"Revisiting the Dissolution Behavior of Interfacial Oxides in Hot-Compression Bonding of a Fe-Cr-Ni Stainless Steel","authors":"Honglin Zhang, Gang Zhou, Ming-yue Sun, Bin Xu, Dianzhong Li, Yiyi Li","doi":"10.2139/ssrn.3790081","DOIUrl":"https://doi.org/10.2139/ssrn.3790081","url":null,"abstract":"Interfacial oxides can be removed by thermodynamic decomposition in the metallic solid-state bonding. Despite adequate observations, the dissolution behavior is not yet well understood. Based on the hot-compression bonding experiments of a Fe-Cr-Ni stainless steel, first-principles calculations are adopted to reveal the diffusion of oxygen in the Cr<sub>2</sub>O<sub>3</sub>/FCC-Fe heterostructure to identify the dissolution process. The results show that the heterogeneous interface favors the formation of oxygen vacancies, and the oxygen prefers to diffuse through the facet of coordination tetrahedron of Cr atoms than their bridge-site. The dissolution of the oxides is dominated by the diffusion of dissociated oxygen to the interface due to its high activation energy of 720 kJ·mol<sup>-1</sup>, while the heterogeneous interface provides a favorable transport channel to allow the oxygen diffuse into iron matrix.","PeriodicalId":18300,"journal":{"name":"MatSciRN: Other Materials Processing & Manufacturing (Topic)","volume":"221 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79022229","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}
Rui Fu, Liang Zheng, Z. Zhong, Xiangnan Pan, Yangping Dong, M. Yan
The high-cycle fatigue (HCF) and very-high-cycle fatigue (VHCF) behaviors of Ti-6Al-4V manufactured by selective laser melting (SLM) were investigated with the consideration of effects of surface roughness and stress ratio. The fatigue testing was performed by an ultrasonic vibration machine with a frequency of 20 kHz. Fatigue cracks initiate from the surface of the as-built SLMed Ti-6Al-4V, but from the subsurface of the surface-polished SLMed Ti-6Al-4V. The size and depth of the defect inducing fatigue crack initiation of as-built SLMed Ti-6Al-4V is much smaller than that of surface-polished SLMed Ti-6Al-4V. Fatigue cracks are much easier to propagate in as-built than surface-polished SLMed Ti-6Al-4V. For surface-polished SLMed Ti-6Al-4V, fatigue cracks have the same difficulty to propagate at R = −1 and 0.5. Analytical models are developed to well predict the fatigue lives of both as-built and surface polished SLMed Ti-6Al-4V under R = −1 and 0.5.
{"title":"Evaluation of Fatigue Behaviors of SLMed Ti-6Al-4V in High-Cycle and Very-High-Cycle Regimes Considering Effects of Stress Ratio and Surface Roughness","authors":"Rui Fu, Liang Zheng, Z. Zhong, Xiangnan Pan, Yangping Dong, M. Yan","doi":"10.2139/ssrn.3893499","DOIUrl":"https://doi.org/10.2139/ssrn.3893499","url":null,"abstract":"The high-cycle fatigue (HCF) and very-high-cycle fatigue (VHCF) behaviors of Ti-6Al-4V manufactured by selective laser melting (SLM) were investigated with the consideration of effects of surface roughness and stress ratio. The fatigue testing was performed by an ultrasonic vibration machine with a frequency of 20 kHz. Fatigue cracks initiate from the surface of the as-built SLMed Ti-6Al-4V, but from the subsurface of the surface-polished SLMed Ti-6Al-4V. The size and depth of the defect inducing fatigue crack initiation of as-built SLMed Ti-6Al-4V is much smaller than that of surface-polished SLMed Ti-6Al-4V. Fatigue cracks are much easier to propagate in as-built than surface-polished SLMed Ti-6Al-4V. For surface-polished SLMed Ti-6Al-4V, fatigue cracks have the same difficulty to propagate at R = −1 and 0.5. Analytical models are developed to well predict the fatigue lives of both as-built and surface polished SLMed Ti-6Al-4V under R = −1 and 0.5.","PeriodicalId":18300,"journal":{"name":"MatSciRN: Other Materials Processing & Manufacturing (Topic)","volume":"4 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82036178","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}
Kohta Nambu, K. Morita, K. Soga, Takahisa Yamamoto, H. Masuda, H. Yoshida
In the present study, frequency dependence of the densification behavior of undoped Y2O3 sintered by the AC-flash sintering was systematically investigated at 500 V·cm−1 over a frequency range from 0.05 Hz to 1 kHz. Flash events occurred at all frequencies when the power dissipation reached 10–20 mW·mm−3. The onset temperature for AC-flash sintering was in the range of 1230 °C–1300 °C. The Y2O3 bodies sintered under an AC field showed a uniform microstructure, without an asymmetric grain size distribution between the electrodes. The onset temperature for the flash sintering, final density, and grain size of the flash sintered specimens depended on the frequency. In particular, the Y2O3 body consolidated at 1 kHz exhibited a relative density greater than 99% and an average grain size of 1.6 μm. This almost full densification probably resulted from the high input power at the relatively high onset temperature of the AC-flash sintering at this frequency. The temperature dependence of the power dissipation during the AC-flash sintering experiments was influenced by the frequency of the applied field. The apparent dependence on the frequency can be ascribed to the periodic fluctuations of the specimen temperature at low frequencies and to the phase shift between the applied field and the specimen current at high frequencies.
{"title":"Densification of Y 2O 3 by Flash Sintering Under an AC Electric Field","authors":"Kohta Nambu, K. Morita, K. Soga, Takahisa Yamamoto, H. Masuda, H. Yoshida","doi":"10.2139/ssrn.3790078","DOIUrl":"https://doi.org/10.2139/ssrn.3790078","url":null,"abstract":"In the present study, frequency dependence of the densification behavior of undoped Y<sub>2</sub>O<sub>3</sub> sintered by the AC-flash sintering was systematically investigated at 500 V·cm<sup>−1</sup> over a frequency range from 0.05 Hz to 1 kHz. Flash events occurred at all frequencies when the power dissipation reached 10–20 mW·mm<sup>−3</sup>. The onset temperature for AC-flash sintering was in the range of 1230 °C–1300 °C. The Y<sub>2</sub>O<sub>3</sub> bodies sintered under an AC field showed a uniform microstructure, without an asymmetric grain size distribution between the electrodes. The onset temperature for the flash sintering, final density, and grain size of the flash sintered specimens depended on the frequency. In particular, the Y<sub>2</sub>O<sub>3</sub> body consolidated at 1 kHz exhibited a relative density greater than 99% and an average grain size of 1.6 μm. This almost full densification probably resulted from the high input power at the relatively high onset temperature of the AC-flash sintering at this frequency. The temperature dependence of the power dissipation during the AC-flash sintering experiments was influenced by the frequency of the applied field. The apparent dependence on the frequency can be ascribed to the periodic fluctuations of the specimen temperature at low frequencies and to the phase shift between the applied field and the specimen current at high frequencies.","PeriodicalId":18300,"journal":{"name":"MatSciRN: Other Materials Processing & Manufacturing (Topic)","volume":"40 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89460642","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}
Abstract We have performed micro pillar compression to investigate the influence of strain rate on the activation of three slip plane families, namely {110}, {112} and {123}, in ferrite of a dual phase steel. The critical resolved shear stress of all three slip plane families rises with increased strain rate. The strain rate sensitivity drops with increasing strain. Increasing strain rate does not reduce the number of activated slip systems, instead resulting in slip plane activation outside of that predicted by Schmid´s law. The activation volume of 13b³ to 16b³ suggests that the Peierl's process is the rate controlling mechanism in ferrite of DP800.
{"title":"Influence of Strain Rate on the Activation of {110}, {112}, {123} Slip in Ferrite of DP800","authors":"Chunhua Tian, G. Dehm, C. Kirchlechner","doi":"10.2139/ssrn.3693553","DOIUrl":"https://doi.org/10.2139/ssrn.3693553","url":null,"abstract":"Abstract We have performed micro pillar compression to investigate the influence of strain rate on the activation of three slip plane families, namely {110}, {112} and {123}, in ferrite of a dual phase steel. The critical resolved shear stress of all three slip plane families rises with increased strain rate. The strain rate sensitivity drops with increasing strain. Increasing strain rate does not reduce the number of activated slip systems, instead resulting in slip plane activation outside of that predicted by Schmid´s law. The activation volume of 13b³ to 16b³ suggests that the Peierl's process is the rate controlling mechanism in ferrite of DP800.","PeriodicalId":18300,"journal":{"name":"MatSciRN: Other Materials Processing & Manufacturing (Topic)","volume":"22 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78734995","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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