Magnesium based nanocomposites are new lightweight and high-performance materials for potential applications in biomedical, electronics, aerospace and automotive sectors owing to their lower density when compared with aluminum-based materials and steel. This article discusses the effect of pulse duration, pulse interval, current, gap voltage on Surface Roughness (SR), Material Removal Rate (MRR) and Electrode Wear Rate (EWR) of AZ61/7.5% B 4 C composites have been studied based on the different dielectric medium, kerosene, Electrical Discharge Machining (EDM) oil and nanosilicon carbide added EDM oil. The magnesium nanocomposites have been prepared through stir casting. The L16 orthogonal array has been selected based on the four factors with four levels. The Complex Proportional Assessment (COPRAS) method has been used to find the optimum process parameters. An overall analysis found that the AZ61/7.5% B 4 C composites has produced high mechanical properties compared with 2.5, 5, and 10wt.% B 4 C nanocomposites. The pulse duration has most influencing factor for affecting the MRR and SR using analysis of variance. The developed quadratic models have well fit with experimental values. Using COPRAS, the optimal parameters are observed to be a maximum of 0.00730 g/s MRR, a minimum of 0.00127 g/s EWR, and a SR of 3.196 µm. The nano-SiC powder with EDM oil has a higher improvement than that of kerosene and EDM oil. The nano-SiC mixed EDM oil produces an improved performance measure of 81% MRR, 55% EWR, and 47% SR.
{"title":"An effect of nano-SiC with different dielectric mediums on AZ61/7.5% B4C nanocomposites studied through electrical discharge machining and Taguchi based complex proportional assessment method","authors":"Sakthi Selvarasu, Mahendran Subramanian, Jayasuthahar Thangasamy","doi":"10.1590/1517-7076-rmat-2023-0058","DOIUrl":"https://doi.org/10.1590/1517-7076-rmat-2023-0058","url":null,"abstract":"Magnesium based nanocomposites are new lightweight and high-performance materials for potential applications in biomedical, electronics, aerospace and automotive sectors owing to their lower density when compared with aluminum-based materials and steel. This article discusses the effect of pulse duration, pulse interval, current, gap voltage on Surface Roughness (SR), Material Removal Rate (MRR) and Electrode Wear Rate (EWR) of AZ61/7.5% B 4 C composites have been studied based on the different dielectric medium, kerosene, Electrical Discharge Machining (EDM) oil and nanosilicon carbide added EDM oil. The magnesium nanocomposites have been prepared through stir casting. The L16 orthogonal array has been selected based on the four factors with four levels. The Complex Proportional Assessment (COPRAS) method has been used to find the optimum process parameters. An overall analysis found that the AZ61/7.5% B 4 C composites has produced high mechanical properties compared with 2.5, 5, and 10wt.% B 4 C nanocomposites. The pulse duration has most influencing factor for affecting the MRR and SR using analysis of variance. The developed quadratic models have well fit with experimental values. Using COPRAS, the optimal parameters are observed to be a maximum of 0.00730 g/s MRR, a minimum of 0.00127 g/s EWR, and a SR of 3.196 µm. The nano-SiC powder with EDM oil has a higher improvement than that of kerosene and EDM oil. The nano-SiC mixed EDM oil produces an improved performance measure of 81% MRR, 55% EWR, and 47% SR.","PeriodicalId":18246,"journal":{"name":"Matéria (Rio de Janeiro)","volume":"34 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-05-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73809511","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 : 2023-05-15DOI: 10.1590/1517-7076-rmat-2023-0026
R. F. Assumpção, D. Sicupira, D. Santos
This study examined the effects of cold working and subsequent annealing treatment for a short time on the corrosion behavior of a lean duplex stainless steel (LDSS). The as-received sample was solution treated at 1100 °C for 1800 s and cold rolled. The cold deformation (75%) was followed by isochronic annealing at 900, 950, 1000, 1050 and 1100 °C for 180 s. The microstructural changes were evaluated by scanning electron microscopy (SEM) and Vickers hardness, while corrosion behavior was investigated by cyclic potentiodynamic polarization technique and electrochemical impedance spectroscopy (EIS) in 3.5% NaCl solution at 22 ± 2 °C. After cyclic polarization, pits morphology was characterized by SEM. Cold rolling lowered lamellar spacing between the phases and increased hardness. Hardness at temperatures higher than 950 °C was equal to the 2304 LDSS solution treated. Although grain refinement is observed due to recrystallization, the corrosion resistance was not significantly improved. The highest pitting potential and charge transfer resistance were obtained after annealing at 1000 °C for 180 s. The pit distribution indicates that the corrosion behavior of the phases changed during the cold rolling and annealing treatment, and pitting was initiated preferentially in the α/γ boundaries and inside the α domains.
{"title":"Corrosion behavior of a 2304 lean duplex stainless steel cold-rolled and short-term annealed at different temperatures","authors":"R. F. Assumpção, D. Sicupira, D. Santos","doi":"10.1590/1517-7076-rmat-2023-0026","DOIUrl":"https://doi.org/10.1590/1517-7076-rmat-2023-0026","url":null,"abstract":"This study examined the effects of cold working and subsequent annealing treatment for a short time on the corrosion behavior of a lean duplex stainless steel (LDSS). The as-received sample was solution treated at 1100 °C for 1800 s and cold rolled. The cold deformation (75%) was followed by isochronic annealing at 900, 950, 1000, 1050 and 1100 °C for 180 s. The microstructural changes were evaluated by scanning electron microscopy (SEM) and Vickers hardness, while corrosion behavior was investigated by cyclic potentiodynamic polarization technique and electrochemical impedance spectroscopy (EIS) in 3.5% NaCl solution at 22 ± 2 °C. After cyclic polarization, pits morphology was characterized by SEM. Cold rolling lowered lamellar spacing between the phases and increased hardness. Hardness at temperatures higher than 950 °C was equal to the 2304 LDSS solution treated. Although grain refinement is observed due to recrystallization, the corrosion resistance was not significantly improved. The highest pitting potential and charge transfer resistance were obtained after annealing at 1000 °C for 180 s. The pit distribution indicates that the corrosion behavior of the phases changed during the cold rolling and annealing treatment, and pitting was initiated preferentially in the α/γ boundaries and inside the α domains.","PeriodicalId":18246,"journal":{"name":"Matéria (Rio de Janeiro)","volume":"29 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-05-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86154938","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 : 2023-05-15DOI: 10.1590/1517-7076-rmat-2022-0304
Hang Shao, Yanlong Wang, Haixia Wan, Hao Wang, Zhongfeng Zhang, W. Fu
Springback is the reverse elastic deformation produced by the unloading process, which is a common phenomenon in the sheet metal stamping and forming process and affects the final forming accuracy of the part. Aiming at the problem of springback error in the multi-point forming process of hyperbolic component for ships, the springback phenomenon of hyperbolic component was studied by combining theoretical analysis, numerical simulation and forming test. The mechanical property parameters and stress-strain curves were obtained by tensile tests using a new corrosion-resistant aluminum alloy as the sheet material. The springback compensation method is introduced, the springback compensation formula based on surface curvature is derived, and the compensated mold surface is further corrected and fitted using the cubic B-sample method. The multi-point punch tooling was generated and modeled by the multi-point 3D modeling software MPFCAD and finite element software to simulate the multi-point forming and unloading springback process of the hyperbolic member. Multi-point forming tests were conducted on a multi-point forming press for corrosion-resistant aluminum alloy hyperbolic component, and the formed parts were checked for accuracy and error analysis by 3D scanning and GOM Inspect software. The results show that the springback compensation method used in this paper can effectively reduce the springback error in the multi-point forming process of corrosion-resistant aluminum alloy hyperbolic component, and the effect is very good.
{"title":"Research on springback compensation for multi-point forming of corrosion-resistant aluminum alloy hyperbolic component","authors":"Hang Shao, Yanlong Wang, Haixia Wan, Hao Wang, Zhongfeng Zhang, W. Fu","doi":"10.1590/1517-7076-rmat-2022-0304","DOIUrl":"https://doi.org/10.1590/1517-7076-rmat-2022-0304","url":null,"abstract":"Springback is the reverse elastic deformation produced by the unloading process, which is a common phenomenon in the sheet metal stamping and forming process and affects the final forming accuracy of the part. Aiming at the problem of springback error in the multi-point forming process of hyperbolic component for ships, the springback phenomenon of hyperbolic component was studied by combining theoretical analysis, numerical simulation and forming test. The mechanical property parameters and stress-strain curves were obtained by tensile tests using a new corrosion-resistant aluminum alloy as the sheet material. The springback compensation method is introduced, the springback compensation formula based on surface curvature is derived, and the compensated mold surface is further corrected and fitted using the cubic B-sample method. The multi-point punch tooling was generated and modeled by the multi-point 3D modeling software MPFCAD and finite element software to simulate the multi-point forming and unloading springback process of the hyperbolic member. Multi-point forming tests were conducted on a multi-point forming press for corrosion-resistant aluminum alloy hyperbolic component, and the formed parts were checked for accuracy and error analysis by 3D scanning and GOM Inspect software. The results show that the springback compensation method used in this paper can effectively reduce the springback error in the multi-point forming process of corrosion-resistant aluminum alloy hyperbolic component, and the effect is very good.","PeriodicalId":18246,"journal":{"name":"Matéria (Rio de Janeiro)","volume":"42 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-05-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79907411","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 : 2023-05-12DOI: 10.1590/1517-7076-rmat-2023-0016
Orlando Preti, Fabio Elias Dalagnolo, Manar N. Krmasha, Kassim S. Al-Rubaie
RESUMO Nos impulsores das bombas centrífugas submersíveis instaladas nas estações elevatórias de esgoto, ocorrem perdas prematuras por desgaste hidroabrasivo, reduzindo drasticamente a eficiência hidráulica e aumento das despesas energéticas do equipamento. A finalidade deste estudo é de contribuir na melhor escolha de material, minimizando as perdas, a partir do desgaste hidroabrasivo das ligas de aço inoxidável super duplex, ferro fundido cinzento temperado e ferro fundido branco de alto cromo, comumente utilizadas em bombas. Além disso, analisou-se o aspecto macrossuperficial das amostras após o ensaio hidroabrasivo. Os testes de desgaste hidroabrasivo foram realizados em uma solução 10:1 de água e areia sílica em duas velocidades de 5,2 m/s e 7,1 m/s. Os testes foram realizados num hidroabrasômetro por 216 horas, com medições de perda de massa feitas em intervalos de 24 horas. Os resultados mostraram que nas velocidades de 5,2 m/s e 7,1 m/s a perda de massa é linear e progressiva, sendo menos acentuada na liga de ferro fundido branco de alto cromo com menor perda de massa ao desgaste hidroabrasivo. Na velocidade de teste de 7,1 m/s resultou em maiores perdas de massa nas ligas estudadas do que a velocidade de teste de 5,2 m/s. As perdas de massa devido ao desgaste hidroabrasivo das ligas investigadas foram relacionadas à dureza, às características microestruturais e à morfologia das superfícies desgastadas. Esses fatores foram utilizados para descrever os resultados e justificar o melhor e o pior desempenho das ligas investigadas. Portanto, o ferro fundido de alto cromo (FBACr) apresentou o melhor desempenho devido a sua alta dureza decorrente de suas características microestruturais (matriz e M7C3), e superfície desgastada que apresenta aspecto brilhante e polido com menos crateras e sulcos que as demais ligas estudadas.
{"title":"Avaliação do desgaste hidroabrasivo em diferentes ligas de impulsores centrífugos submersíveis utilizados no bombeamento de esgoto em estações elevatórias","authors":"Orlando Preti, Fabio Elias Dalagnolo, Manar N. Krmasha, Kassim S. Al-Rubaie","doi":"10.1590/1517-7076-rmat-2023-0016","DOIUrl":"https://doi.org/10.1590/1517-7076-rmat-2023-0016","url":null,"abstract":"RESUMO Nos impulsores das bombas centrífugas submersíveis instaladas nas estações elevatórias de esgoto, ocorrem perdas prematuras por desgaste hidroabrasivo, reduzindo drasticamente a eficiência hidráulica e aumento das despesas energéticas do equipamento. A finalidade deste estudo é de contribuir na melhor escolha de material, minimizando as perdas, a partir do desgaste hidroabrasivo das ligas de aço inoxidável super duplex, ferro fundido cinzento temperado e ferro fundido branco de alto cromo, comumente utilizadas em bombas. Além disso, analisou-se o aspecto macrossuperficial das amostras após o ensaio hidroabrasivo. Os testes de desgaste hidroabrasivo foram realizados em uma solução 10:1 de água e areia sílica em duas velocidades de 5,2 m/s e 7,1 m/s. Os testes foram realizados num hidroabrasômetro por 216 horas, com medições de perda de massa feitas em intervalos de 24 horas. Os resultados mostraram que nas velocidades de 5,2 m/s e 7,1 m/s a perda de massa é linear e progressiva, sendo menos acentuada na liga de ferro fundido branco de alto cromo com menor perda de massa ao desgaste hidroabrasivo. Na velocidade de teste de 7,1 m/s resultou em maiores perdas de massa nas ligas estudadas do que a velocidade de teste de 5,2 m/s. As perdas de massa devido ao desgaste hidroabrasivo das ligas investigadas foram relacionadas à dureza, às características microestruturais e à morfologia das superfícies desgastadas. Esses fatores foram utilizados para descrever os resultados e justificar o melhor e o pior desempenho das ligas investigadas. Portanto, o ferro fundido de alto cromo (FBACr) apresentou o melhor desempenho devido a sua alta dureza decorrente de suas características microestruturais (matriz e M7C3), e superfície desgastada que apresenta aspecto brilhante e polido com menos crateras e sulcos que as demais ligas estudadas.","PeriodicalId":18246,"journal":{"name":"Matéria (Rio de Janeiro)","volume":"165 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-05-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87699800","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 : 2023-05-12DOI: 10.1590/1517-7076-rmat-2023-0079
Ye Jixing, Pan Zhu, Luo Junhui
Through orthogonal experimental design, the influence of the water-binder ratio, binder-sand ratio, ultrafine mineral admixture content, and steel fiber content on the fluidity and basic mechanical properties of rapid-repair materials was studied. The optimal mixing ratio parameters were determined, and its swelling and shrinkage performance and microstructure were analyzed. The results showed that the water-binder ratio and steel fiber content were the most significant factors affecting the properties of rapid-repair materials. The steel fiber content in the rapid-repair material led to pull-out failure and significantly affected flexural strength but had a relatively small effect on compressive strength. With the determined optimal mix proportion, the rapid-repair material had good fluidity and high early strength, bonding strength, and volume stability. At age 3 h, the material’s flexural strength and compressive strength were 13.7 MPa and 27.8 MPa, respectively, and the adhesive strength was 3.65 MPa. The limited expansion rate of 56 d-age repair material was 326.5 × 10 −6 , which can better meet the requirements of repairing highway pavement and bridge expansion joints to reopen to traffic within 3 h of repair.
{"title":"Optimization of rapid-repair material ratio and performance analysis based on orthogonal test","authors":"Ye Jixing, Pan Zhu, Luo Junhui","doi":"10.1590/1517-7076-rmat-2023-0079","DOIUrl":"https://doi.org/10.1590/1517-7076-rmat-2023-0079","url":null,"abstract":"Through orthogonal experimental design, the influence of the water-binder ratio, binder-sand ratio, ultrafine mineral admixture content, and steel fiber content on the fluidity and basic mechanical properties of rapid-repair materials was studied. The optimal mixing ratio parameters were determined, and its swelling and shrinkage performance and microstructure were analyzed. The results showed that the water-binder ratio and steel fiber content were the most significant factors affecting the properties of rapid-repair materials. The steel fiber content in the rapid-repair material led to pull-out failure and significantly affected flexural strength but had a relatively small effect on compressive strength. With the determined optimal mix proportion, the rapid-repair material had good fluidity and high early strength, bonding strength, and volume stability. At age 3 h, the material’s flexural strength and compressive strength were 13.7 MPa and 27.8 MPa, respectively, and the adhesive strength was 3.65 MPa. The limited expansion rate of 56 d-age repair material was 326.5 × 10 −6 , which can better meet the requirements of repairing highway pavement and bridge expansion joints to reopen to traffic within 3 h of repair.","PeriodicalId":18246,"journal":{"name":"Matéria (Rio de Janeiro)","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-05-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85710118","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 : 2023-05-08DOI: 10.1590/1517-7076-rmat-2023-0072
Xingyuan Chen, L. Wang, Xiangpeng Wang, Ruixuan Wang, Wentao Su
In this paper, based on the analysis of oil sludge composition and environmental hazards, the microwave catalytic pyrolysis of oil sludge for recovering combustible gas and chain hydrocarbon light oil disposal process, is proposed to perform the recycling of oil sludge and reduce the risk of environmental pollution. In order to improve the yield of combustible gas and light oil in oil sludge pyrolysis, the impact of adding four catalysts (nano-CuO, nano-NiO, nano-MgO, and nano-γ-Al 2 O 3 ) on the heating characteristics of oil sludge and the composition and quality of products during microwave pyrolysis, were experimentally studied and analyzed. The results show that the catalyst can increase the heating rate of sludge and the yield of pyrolysis oil and gas. The increasing order of heating is: nano-CuO > nano-γ-Al 2 O 3 > nano-MgO > nano-NiO > blank group. Compared with the blank group, the content of combustible gas (H 2 + CH 4 + CO) increases by 18.824wt% (MgO), 4.511wt% (CuO), 9.28wt% (NiO), and 16.164wt% (γ-Al 2 O 3 ), respectively. It can be deduced that nano-metal oxide catalysts, especially γ-Al 2 O 3 , can promote the decomposition of oil sludge, improve the content of low carbon straight chain hydrocarbons and alcohols, and improve the quality of pyrolysis oil products.
{"title":"Effect of nano-metal oxides types on oil sludge during microwave pyrolysis","authors":"Xingyuan Chen, L. Wang, Xiangpeng Wang, Ruixuan Wang, Wentao Su","doi":"10.1590/1517-7076-rmat-2023-0072","DOIUrl":"https://doi.org/10.1590/1517-7076-rmat-2023-0072","url":null,"abstract":"In this paper, based on the analysis of oil sludge composition and environmental hazards, the microwave catalytic pyrolysis of oil sludge for recovering combustible gas and chain hydrocarbon light oil disposal process, is proposed to perform the recycling of oil sludge and reduce the risk of environmental pollution. In order to improve the yield of combustible gas and light oil in oil sludge pyrolysis, the impact of adding four catalysts (nano-CuO, nano-NiO, nano-MgO, and nano-γ-Al 2 O 3 ) on the heating characteristics of oil sludge and the composition and quality of products during microwave pyrolysis, were experimentally studied and analyzed. The results show that the catalyst can increase the heating rate of sludge and the yield of pyrolysis oil and gas. The increasing order of heating is: nano-CuO > nano-γ-Al 2 O 3 > nano-MgO > nano-NiO > blank group. Compared with the blank group, the content of combustible gas (H 2 + CH 4 + CO) increases by 18.824wt% (MgO), 4.511wt% (CuO), 9.28wt% (NiO), and 16.164wt% (γ-Al 2 O 3 ), respectively. It can be deduced that nano-metal oxide catalysts, especially γ-Al 2 O 3 , can promote the decomposition of oil sludge, improve the content of low carbon straight chain hydrocarbons and alcohols, and improve the quality of pyrolysis oil products.","PeriodicalId":18246,"journal":{"name":"Matéria (Rio de Janeiro)","volume":"5 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73462968","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 : 2023-05-05DOI: 10.1590/1517-7076-rmat-2023-0096
Xing-chen Li, D. Chang, You-gang Sun
Digital welding machine (DWM) is an advanced tool for material forming. The lifespan and health status of DWMs are closely related to the safety and reliability. To address the problem of low accuracy in the lifespan prediction of DWMs, a model based on immune algorithm (IA) and long short-term memory network (LSTM) with attention mechanism is proposed. First, the degradation characteristic indicators of the lifespan of DWMs are evaluated and selected. Then, a health index is constructed using linear regression to quantitatively reflect the lifespan status of DWMs. The optimized model is used to predict the remaining lifespan, and compared with various models using 5 indicators. Finally, predictive maintenance of DWMs is carried out based on product inspection and production scheduling. the optimal solution for the objective function is obtained to calculate the best predictive maintenance method for the digital welding machine.During the lifespan prediction process, the optimized model has a 20% decrease in root mean square error and a 35.8% decrease in mean square error compared to the traditional LSTM model. The average absolute error is decreased by 14.2% and the average absolute percentage error is closer to 0, while the coefficient of determination increases by 23%. By combining with actual production line arrangements, maintenance of DWMs can be performed at the most appropriate time to minimize maintenance costs.
{"title":"Data-driven predictive maintenance method for digital welding machines","authors":"Xing-chen Li, D. Chang, You-gang Sun","doi":"10.1590/1517-7076-rmat-2023-0096","DOIUrl":"https://doi.org/10.1590/1517-7076-rmat-2023-0096","url":null,"abstract":"Digital welding machine (DWM) is an advanced tool for material forming. The lifespan and health status of DWMs are closely related to the safety and reliability. To address the problem of low accuracy in the lifespan prediction of DWMs, a model based on immune algorithm (IA) and long short-term memory network (LSTM) with attention mechanism is proposed. First, the degradation characteristic indicators of the lifespan of DWMs are evaluated and selected. Then, a health index is constructed using linear regression to quantitatively reflect the lifespan status of DWMs. The optimized model is used to predict the remaining lifespan, and compared with various models using 5 indicators. Finally, predictive maintenance of DWMs is carried out based on product inspection and production scheduling. the optimal solution for the objective function is obtained to calculate the best predictive maintenance method for the digital welding machine.During the lifespan prediction process, the optimized model has a 20% decrease in root mean square error and a 35.8% decrease in mean square error compared to the traditional LSTM model. The average absolute error is decreased by 14.2% and the average absolute percentage error is closer to 0, while the coefficient of determination increases by 23%. By combining with actual production line arrangements, maintenance of DWMs can be performed at the most appropriate time to minimize maintenance costs.","PeriodicalId":18246,"journal":{"name":"Matéria (Rio de Janeiro)","volume":"31 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-05-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85915502","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 : 2023-05-05DOI: 10.1590/1517-7076-rmat-2023-0042
S. Oliveira, Laura Soranço, T. Pereira, Bernardo Games, C. Ferreira, Maria Teresa Gomes Barbosa
RESUMO A pandemia do coronavírus além da crise de saúde global evidencia prejuízos ao meio ambiente devido ao elevado número de máscaras faciais descartadas, tornando necessário o desenvolvimento de pesquisas para minimizar os riscos ambientais associados aos de equipamentos de proteção individual utilizados pela população. Este estudo visa reduzir os resíduos gerados pela pandemia, aproveitando as máscaras faciais, inserindo-as na confecção de argamassas. Efetuou-se processamento (trituramento) das máscaras e sua inclusão em teores de 1,4% e 2,0% em relação ao consumo de cimento. Os produtos foram comparados com um traço de referência e avaliados quanto às propriedades físicas e mecânicas. Como resultado, constatou-se que a adição do fibras da máscara interfere nas propriedades ocasionando um incremento na taxa de absorção de água, bem como reduções na resistência à tração e à compressão, respectivamente 30% e 50%, em decorrência de falhas na interação matriz/fibra, o que poderá limitar o emprego da mistura. Entretanto, o presente estudo contribui para a agenda brasileira no que se refere ao desenvolvimento sustentável urbano, regional e nacional, através de uma abordagem inovadora, possibilitando a redução da degradação ambiental pelo descarte das máscaras e a confecção de novos materiais a serem empregados no setor da construção civil.
{"title":"Estudo da adição de fibras de máscaras faciais N95, sílica ativa e pó de mármore em argamassa de alto desempenho","authors":"S. Oliveira, Laura Soranço, T. Pereira, Bernardo Games, C. Ferreira, Maria Teresa Gomes Barbosa","doi":"10.1590/1517-7076-rmat-2023-0042","DOIUrl":"https://doi.org/10.1590/1517-7076-rmat-2023-0042","url":null,"abstract":"RESUMO A pandemia do coronavírus além da crise de saúde global evidencia prejuízos ao meio ambiente devido ao elevado número de máscaras faciais descartadas, tornando necessário o desenvolvimento de pesquisas para minimizar os riscos ambientais associados aos de equipamentos de proteção individual utilizados pela população. Este estudo visa reduzir os resíduos gerados pela pandemia, aproveitando as máscaras faciais, inserindo-as na confecção de argamassas. Efetuou-se processamento (trituramento) das máscaras e sua inclusão em teores de 1,4% e 2,0% em relação ao consumo de cimento. Os produtos foram comparados com um traço de referência e avaliados quanto às propriedades físicas e mecânicas. Como resultado, constatou-se que a adição do fibras da máscara interfere nas propriedades ocasionando um incremento na taxa de absorção de água, bem como reduções na resistência à tração e à compressão, respectivamente 30% e 50%, em decorrência de falhas na interação matriz/fibra, o que poderá limitar o emprego da mistura. Entretanto, o presente estudo contribui para a agenda brasileira no que se refere ao desenvolvimento sustentável urbano, regional e nacional, através de uma abordagem inovadora, possibilitando a redução da degradação ambiental pelo descarte das máscaras e a confecção de novos materiais a serem empregados no setor da construção civil.","PeriodicalId":18246,"journal":{"name":"Matéria (Rio de Janeiro)","volume":"47 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-05-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75809542","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 : 2023-05-05DOI: 10.1590/1517-7076-rmat-2022-0298
Marcelly de Figueiredo Mendonça, Marcelo Martins Farias, Celestina Lima de Rezende Farias, M. S. Picanço, Alcibíades Negrão Macêdo
Partial replacement of Portland cement by industrial waste or materials of natural origin can improve the mechanical strength of concrete and mortar and reduce production cost. In this context, ash from burning bamboo appears as a potential material for use, as it is natural with a renewable source and fast growth, which presents a higher concentration of silica in the outer walls of the stalks. Therefore, the objective of this work is to evaluate the use of bamboo stalk ash (Bambusa Vulgaris) as a partial replacement for Portland cement. For this purpose, bamboo ash was produced at three calcination temperatures (500ºC, 600ºC and 700ºC). The ashes were not characterized as pozzolans based on their chemical composition, however the ash produced at 600ºC obtained a performance index higher than that established by the Standard. The hydration of cement partially replaced by this ash was evaluated, in proportions of 0%, 6%, 10% and 14%, in relation to its mass. Mortars with the same replacement proportions were evaluated in the fresh state and hardened. The consistency in the fresh state remained constant at 227 mm, while the compressive strength, in the hardened state, increased by 15% with the addition of bamboo stem ash.
{"title":"Partial replacement of portland cement by bamboo ashes","authors":"Marcelly de Figueiredo Mendonça, Marcelo Martins Farias, Celestina Lima de Rezende Farias, M. S. Picanço, Alcibíades Negrão Macêdo","doi":"10.1590/1517-7076-rmat-2022-0298","DOIUrl":"https://doi.org/10.1590/1517-7076-rmat-2022-0298","url":null,"abstract":"Partial replacement of Portland cement by industrial waste or materials of natural origin can improve the mechanical strength of concrete and mortar and reduce production cost. In this context, ash from burning bamboo appears as a potential material for use, as it is natural with a renewable source and fast growth, which presents a higher concentration of silica in the outer walls of the stalks. Therefore, the objective of this work is to evaluate the use of bamboo stalk ash (Bambusa Vulgaris) as a partial replacement for Portland cement. For this purpose, bamboo ash was produced at three calcination temperatures (500ºC, 600ºC and 700ºC). The ashes were not characterized as pozzolans based on their chemical composition, however the ash produced at 600ºC obtained a performance index higher than that established by the Standard. The hydration of cement partially replaced by this ash was evaluated, in proportions of 0%, 6%, 10% and 14%, in relation to its mass. Mortars with the same replacement proportions were evaluated in the fresh state and hardened. The consistency in the fresh state remained constant at 227 mm, while the compressive strength, in the hardened state, increased by 15% with the addition of bamboo stem ash.","PeriodicalId":18246,"journal":{"name":"Matéria (Rio de Janeiro)","volume":"3 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-05-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85771069","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 : 2023-05-01DOI: 10.1590/1517-7076-rmat-2023-0003
Krishnasamy Ravikumar, Saravanakumar Palanichamy, Christian Johnson Singaram, Mohanraj Rajendran
The significant features of the GFRP angle make it one of the modern construction members for the present lattice-type Transmission Line Towers (TLT) made out of mild steel. The GFRP structural angle members with gusset plate connections for net-crushing strength are investigated in this study, with an emphasis on connections to transmission line towers. Forty-two specimens of single-lap, butt joints with bolted connections are considered in this study. The gusset plate and edge distance have different widths. The joint is subjected to a compression load before failure modes and the associated loads were noticed. An experimental investigation on the crushing behaviour of GFRP angle sections to determine the crushing performance against the standard crushing force of different connections such as bolted, adhesive, and hybrid (bolted + adhesive) with various joints (butt and lap) has been carried out and are presented. Additionally, the impact of plate edge distance and width on connection effectiveness is investigated. The innovation of the work is in the evaluation of the crushing value for bolted GFRP structural angle members of 2, 3, and 4 nos with gusset plate connections that have been used to predict the compressive strength.
{"title":"Crushing performance of pultruded GFRP angle section with various connections and joints on lattice towers","authors":"Krishnasamy Ravikumar, Saravanakumar Palanichamy, Christian Johnson Singaram, Mohanraj Rajendran","doi":"10.1590/1517-7076-rmat-2023-0003","DOIUrl":"https://doi.org/10.1590/1517-7076-rmat-2023-0003","url":null,"abstract":"The significant features of the GFRP angle make it one of the modern construction members for the present lattice-type Transmission Line Towers (TLT) made out of mild steel. The GFRP structural angle members with gusset plate connections for net-crushing strength are investigated in this study, with an emphasis on connections to transmission line towers. Forty-two specimens of single-lap, butt joints with bolted connections are considered in this study. The gusset plate and edge distance have different widths. The joint is subjected to a compression load before failure modes and the associated loads were noticed. An experimental investigation on the crushing behaviour of GFRP angle sections to determine the crushing performance against the standard crushing force of different connections such as bolted, adhesive, and hybrid (bolted + adhesive) with various joints (butt and lap) has been carried out and are presented. Additionally, the impact of plate edge distance and width on connection effectiveness is investigated. The innovation of the work is in the evaluation of the crushing value for bolted GFRP structural angle members of 2, 3, and 4 nos with gusset plate connections that have been used to predict the compressive strength.","PeriodicalId":18246,"journal":{"name":"Matéria (Rio de Janeiro)","volume":"100 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76992453","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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