Vesela Tabakova, Christina Klug, Thomas H. Schmitz
This paper examines the application of non-synthetic particle suspensions as a support medium for the additive manufacturing of complex doubly curved ceramic shells with overhangs between 0° and 90° using clay paste. In this method, the build-up material is injected within a constant volume of air-permeable particle suspension. As the used clay paste does not solidify right after injection, the suspension operates like a support medium and enables various print path strategies. Different non-synthetic suspension mixtures, including solid and flexible components such as quartz sand, refractory clay, various types of wood shavings, and cotton flocks, were evaluated for their ability to securely hold the injected material while allowing drying of the water-based clay body and its shrinkage. The balance between grain composition, added water, and the compressibility of the mixture during printing and drying played a pivotal role in the particle suspension design and assessment. Furthermore, the moisture absorption of the particle suspension and the structural integrity of the layer bond of the fired ceramics were also assessed. The examined additive manufacturing process not only enables the production of meso-scale doubly curved ceramic shells with average overhang of 56° but also introduces a new practice for designing specialized surfaces and constructions.
{"title":"Injection 3D Printing of Doubly Curved Ceramic Shells in Non-Synthetic Particle Suspensions","authors":"Vesela Tabakova, Christina Klug, Thomas H. Schmitz","doi":"10.3390/ma17163955","DOIUrl":"https://doi.org/10.3390/ma17163955","url":null,"abstract":"This paper examines the application of non-synthetic particle suspensions as a support medium for the additive manufacturing of complex doubly curved ceramic shells with overhangs between 0° and 90° using clay paste. In this method, the build-up material is injected within a constant volume of air-permeable particle suspension. As the used clay paste does not solidify right after injection, the suspension operates like a support medium and enables various print path strategies. Different non-synthetic suspension mixtures, including solid and flexible components such as quartz sand, refractory clay, various types of wood shavings, and cotton flocks, were evaluated for their ability to securely hold the injected material while allowing drying of the water-based clay body and its shrinkage. The balance between grain composition, added water, and the compressibility of the mixture during printing and drying played a pivotal role in the particle suspension design and assessment. Furthermore, the moisture absorption of the particle suspension and the structural integrity of the layer bond of the fired ceramics were also assessed. The examined additive manufacturing process not only enables the production of meso-scale doubly curved ceramic shells with average overhang of 56° but also introduces a new practice for designing specialized surfaces and constructions.","PeriodicalId":503043,"journal":{"name":"Materials","volume":"33 4","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-08-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141923508","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}
N. Baldino, O. Mileti, Y. Marchesano, F. R. Lupi, D. Gabriele, Massimo Paolini
Traditional recycled asphalt pavement (RAP) binder extraction is not a cost-effective and sustainable option for a quick field study because it requires the use of a huge amount of solvent. Hence, most of the studies on asphalt pavement are carried out with laboratory-aged bitumen in accordance with well-established procedures, i.e., the pressure aging vessel (PAV). Unfortunately, some studies highlight the differences between bitumen aged in the laboratory and in service because it is difficult to reproduce extreme conditions such as real conditions, both atmospheric and load; and this also affects the choice and use of rejuvenators, sometimes compromising the interpretation of results. This study aims to compare the thermo-rheological behavior of a 70/100 bitumen aged with the PAV and two different binders extracted by RAPs. The rheological performances of bitumens were compared in temperature and by dynamic oscillatory tests and steady-state tests, resulting in strength and viscosity values higher for samples with RAP binders compared to the PAV sample. The same bitumens were tested with the addition of a 3% w/w of soybean oil (SO). The results show a decrease in the moduli and viscosity at all the temperatures investigated when SO is added to the laboratory-aged bitumen, while no appreciable differences are evident on naturally aged samples added with SO. Differences were evaluated in terms of cross-over frequency and rheological parameters. Furthermore, the SO effect showed substantial differences, especially in viscosity values, indicating that the study of regenerated or modified bitumen from aged bitumen still requires study, as current standard techniques and procedures cannot emulate real aging conditions well.
{"title":"Rheological Performance and Differences between Laboratory-Aged and RAP Bitumen","authors":"N. Baldino, O. Mileti, Y. Marchesano, F. R. Lupi, D. Gabriele, Massimo Paolini","doi":"10.3390/ma17163954","DOIUrl":"https://doi.org/10.3390/ma17163954","url":null,"abstract":"Traditional recycled asphalt pavement (RAP) binder extraction is not a cost-effective and sustainable option for a quick field study because it requires the use of a huge amount of solvent. Hence, most of the studies on asphalt pavement are carried out with laboratory-aged bitumen in accordance with well-established procedures, i.e., the pressure aging vessel (PAV). Unfortunately, some studies highlight the differences between bitumen aged in the laboratory and in service because it is difficult to reproduce extreme conditions such as real conditions, both atmospheric and load; and this also affects the choice and use of rejuvenators, sometimes compromising the interpretation of results. This study aims to compare the thermo-rheological behavior of a 70/100 bitumen aged with the PAV and two different binders extracted by RAPs. The rheological performances of bitumens were compared in temperature and by dynamic oscillatory tests and steady-state tests, resulting in strength and viscosity values higher for samples with RAP binders compared to the PAV sample. The same bitumens were tested with the addition of a 3% w/w of soybean oil (SO). The results show a decrease in the moduli and viscosity at all the temperatures investigated when SO is added to the laboratory-aged bitumen, while no appreciable differences are evident on naturally aged samples added with SO. Differences were evaluated in terms of cross-over frequency and rheological parameters. Furthermore, the SO effect showed substantial differences, especially in viscosity values, indicating that the study of regenerated or modified bitumen from aged bitumen still requires study, as current standard techniques and procedures cannot emulate real aging conditions well.","PeriodicalId":503043,"journal":{"name":"Materials","volume":"30 17","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-08-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141924773","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}
Emad A. Abood, Marwa Hameed Abdallah, Mahmood Alsaadi, Hamza Imran, L. Bernardo, D. De Domenico, Sadiq N. Henedy
Fiber-reinforced polymers (FRPs) are increasingly being used as a composite material in concrete slabs due to their high strength-to-weight ratio and resistance to corrosion. However, FRP-reinforced concrete slabs, similar to traditional systems, are susceptible to punching shear failure, a critical design concern. Existing empirical models and design provisions for predicting the punching shear strength of FRP-reinforced concrete slabs often exhibit significant bias and dispersion. These errors highlight the need for more reliable predictive models. This study aims to develop gradient-boosted regression tree (GBRT) models to accurately predict the shear strength of FRP-reinforced concrete panels and to address the limitations of existing empirical models. A comprehensive database of 238 sets of experimental results for FRP-reinforced concrete slabs has been compiled from the literature. Different machine learning algorithms were considered, and the performance of GBRT models was evaluated against these algorithms. The dataset was divided into training and testing sets to verify the accuracy of the model. The results indicated that the GBRT model achieved the highest prediction accuracy, with root mean square error (RMSE) of 64.85, mean absolute error (MAE) of 42.89, and coefficient of determination (R2) of 0.955. Comparative analysis with existing experimental models showed that the GBRT model outperformed these traditional approaches. The SHapley Additive exPlanation (SHAP) method was used to interpret the GBRT model, providing insight into the contribution of each input variable to the prediction of punching shear strength. The analysis emphasized the importance of variables such as slab thickness, FRP reinforcement ratio, and critical section perimeter. This study demonstrates the effectiveness of the GBRT model in predicting the punching shear strength of FRP-reinforced concrete slabs with high accuracy. SHAP analysis elucidates key factors that influence model predictions and provides valuable insights for future research and design improvements.
{"title":"Machine Learning-Based Prediction Models for Punching Shear Strength of Fiber-Reinforced Polymer Reinforced Concrete Slabs Using a Gradient-Boosted Regression Tree","authors":"Emad A. Abood, Marwa Hameed Abdallah, Mahmood Alsaadi, Hamza Imran, L. Bernardo, D. De Domenico, Sadiq N. Henedy","doi":"10.3390/ma17163964","DOIUrl":"https://doi.org/10.3390/ma17163964","url":null,"abstract":"Fiber-reinforced polymers (FRPs) are increasingly being used as a composite material in concrete slabs due to their high strength-to-weight ratio and resistance to corrosion. However, FRP-reinforced concrete slabs, similar to traditional systems, are susceptible to punching shear failure, a critical design concern. Existing empirical models and design provisions for predicting the punching shear strength of FRP-reinforced concrete slabs often exhibit significant bias and dispersion. These errors highlight the need for more reliable predictive models. This study aims to develop gradient-boosted regression tree (GBRT) models to accurately predict the shear strength of FRP-reinforced concrete panels and to address the limitations of existing empirical models. A comprehensive database of 238 sets of experimental results for FRP-reinforced concrete slabs has been compiled from the literature. Different machine learning algorithms were considered, and the performance of GBRT models was evaluated against these algorithms. The dataset was divided into training and testing sets to verify the accuracy of the model. The results indicated that the GBRT model achieved the highest prediction accuracy, with root mean square error (RMSE) of 64.85, mean absolute error (MAE) of 42.89, and coefficient of determination (R2) of 0.955. Comparative analysis with existing experimental models showed that the GBRT model outperformed these traditional approaches. The SHapley Additive exPlanation (SHAP) method was used to interpret the GBRT model, providing insight into the contribution of each input variable to the prediction of punching shear strength. The analysis emphasized the importance of variables such as slab thickness, FRP reinforcement ratio, and critical section perimeter. This study demonstrates the effectiveness of the GBRT model in predicting the punching shear strength of FRP-reinforced concrete slabs with high accuracy. SHAP analysis elucidates key factors that influence model predictions and provides valuable insights for future research and design improvements.","PeriodicalId":503043,"journal":{"name":"Materials","volume":"3 12","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-08-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141921589","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}
Tungsten and its alloys have a high atomic number, high melting temperature, and high thermal conductivity, which make them fairly appropriate for use in nuclear applications in an extremely harsh radioactive environment. In recent years, there has been growing research interest in using additive manufacturing techniques to produce tungsten components with complex structures. However, the critical bottleneck for tungsten engineering manufacturing is the high melting temperature and high ductile-to-brittle transition temperature. In this study, laser powder bed fusion has been studied to produce bulk pure tungsten. And finite element analysis was used to simulate the temperature and stress field during laser irradiation. The as-printed surface as well as transverse sections were observed by optical microscopy and scanning electron microscopy to quantitatively study processing defects. The simulated temperature field suggests small-sized powder is beneficial for homogenous melting and provides guidelines for the selection of laser energy density. The experimental results show that ultra-dense tungsten bulk has been successfully obtained within a volumetric energy density of 200–391 J/mm3. The obtained relative density can be as high as 99.98%. By quantitative analysis of the pores and surface cracks, the relationships of cracks and pores with laser volumetric energy density have been phenomenologically established. The results are beneficial for controlling defects and surface quality in future engineering applications of tungsten components by additive manufacturing.
{"title":"Simulation and Experimental Investigation on Additive Manufacturing of Highly Dense Pure Tungsten by Laser Powder Bed Fusion","authors":"Enwei Qin, Wenli Li, Hongzhi Zhou, Chengwei Liu, Shuhui Wu, Gaolian Shi","doi":"10.3390/ma17163966","DOIUrl":"https://doi.org/10.3390/ma17163966","url":null,"abstract":"Tungsten and its alloys have a high atomic number, high melting temperature, and high thermal conductivity, which make them fairly appropriate for use in nuclear applications in an extremely harsh radioactive environment. In recent years, there has been growing research interest in using additive manufacturing techniques to produce tungsten components with complex structures. However, the critical bottleneck for tungsten engineering manufacturing is the high melting temperature and high ductile-to-brittle transition temperature. In this study, laser powder bed fusion has been studied to produce bulk pure tungsten. And finite element analysis was used to simulate the temperature and stress field during laser irradiation. The as-printed surface as well as transverse sections were observed by optical microscopy and scanning electron microscopy to quantitatively study processing defects. The simulated temperature field suggests small-sized powder is beneficial for homogenous melting and provides guidelines for the selection of laser energy density. The experimental results show that ultra-dense tungsten bulk has been successfully obtained within a volumetric energy density of 200–391 J/mm3. The obtained relative density can be as high as 99.98%. By quantitative analysis of the pores and surface cracks, the relationships of cracks and pores with laser volumetric energy density have been phenomenologically established. The results are beneficial for controlling defects and surface quality in future engineering applications of tungsten components by additive manufacturing.","PeriodicalId":503043,"journal":{"name":"Materials","volume":"60 10","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-08-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141922675","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}
R. S. Singh Raman, Lokesh Choudhary, Dan Shechtman
This study investigated the simulated body fluid-assisted stress corrosion cracking (SCC) of an Al-free magnesium alloy (RS66) and a common Al-containing magnesium alloy (AZ91), the former being more suitable for temporary implant applications (however, we used AZ91 for comparison since there are considerable reports on SCC in this alloy). The investigation includes SCC tests under simultaneous conditions of mechanical loading and imposed electrochemical potential that established a combined effect of hydrogen and anodic dissolution as the embrittlement mechanism. Though the RS66 alloy possesses impressive mechanical properties in non-corrosive environments (as a result of its fine grain size), both alloys suffered significant embrittlement when tested in simulated body fluid. The susceptibility of the RS66 alloy to SCC was ~25% greater than that of AZ91, which is attributed to the greater resistance of AZ91 to corrosion/localised corrosion because of its Al content.
{"title":"Simulated Body Fluid-Assisted Stress Corrosion Cracking of a Rapidly Solidified Magnesium Alloy RS66","authors":"R. S. Singh Raman, Lokesh Choudhary, Dan Shechtman","doi":"10.3390/ma17163967","DOIUrl":"https://doi.org/10.3390/ma17163967","url":null,"abstract":"This study investigated the simulated body fluid-assisted stress corrosion cracking (SCC) of an Al-free magnesium alloy (RS66) and a common Al-containing magnesium alloy (AZ91), the former being more suitable for temporary implant applications (however, we used AZ91 for comparison since there are considerable reports on SCC in this alloy). The investigation includes SCC tests under simultaneous conditions of mechanical loading and imposed electrochemical potential that established a combined effect of hydrogen and anodic dissolution as the embrittlement mechanism. Though the RS66 alloy possesses impressive mechanical properties in non-corrosive environments (as a result of its fine grain size), both alloys suffered significant embrittlement when tested in simulated body fluid. The susceptibility of the RS66 alloy to SCC was ~25% greater than that of AZ91, which is attributed to the greater resistance of AZ91 to corrosion/localised corrosion because of its Al content.","PeriodicalId":503043,"journal":{"name":"Materials","volume":"76 18","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-08-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141922226","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}
Longitudinal corrugated tubes (LCTs) exhibit stable platform force under axial compression but have low specific energy absorption. Conversely, circumferential corrugated tubes (CCTs) offer higher specific energy absorption but with unstable platform force. To overcome these limitations, this paper introduces a novel bi-directional corrugated tube (BCT) that amalgamates the strengths of both the CCT and LCT while mitigating their weaknesses. The BCT is formed by rolling a bi-directional corrugated structure into a circular tubular form. Numerical simulations of the BCT closely align with experimental results. The study further examines the influence of discrete parameters on the BCT’s performance through simulations and identifies the tube’s optimal design using the integral entropy TOPSIS method. A full factorial experimental approach is then employed to investigate the impact of radial amplitude, axial amplitude, and neutral surface diameter on the crushing behavior of the BCT, comparing it with the CCT and LCT. The results reveal that increasing Ai enhances the axial resistance of the structure, while increasing Aj reduces the buckling effect, resulting in a higher specific energy absorption and lower ultimate load capacity for the BCT compared to the CCT and LCT. A simultaneous multi-objective optimization of the CCT, LCT, and BCT confirms that the BCT offers superior specific energy absorption and ultimate load capacity. The optimal configuration parameters for the BCT have been determined, providing significant insights for practical applications in crashworthiness engineering.
{"title":"Crashworthiness Performance and Multi-Objective Optimization of Bi-Directional Corrugated Tubes under Quasi-Static Axial Crushing","authors":"Liuxiao Zou, Xin Wang, Ruojun Wang, Xin Huang, Menglei Li, Shuai Li, Zengyan Jiang, Weilong Yin","doi":"10.3390/ma17163958","DOIUrl":"https://doi.org/10.3390/ma17163958","url":null,"abstract":"Longitudinal corrugated tubes (LCTs) exhibit stable platform force under axial compression but have low specific energy absorption. Conversely, circumferential corrugated tubes (CCTs) offer higher specific energy absorption but with unstable platform force. To overcome these limitations, this paper introduces a novel bi-directional corrugated tube (BCT) that amalgamates the strengths of both the CCT and LCT while mitigating their weaknesses. The BCT is formed by rolling a bi-directional corrugated structure into a circular tubular form. Numerical simulations of the BCT closely align with experimental results. The study further examines the influence of discrete parameters on the BCT’s performance through simulations and identifies the tube’s optimal design using the integral entropy TOPSIS method. A full factorial experimental approach is then employed to investigate the impact of radial amplitude, axial amplitude, and neutral surface diameter on the crushing behavior of the BCT, comparing it with the CCT and LCT. The results reveal that increasing Ai enhances the axial resistance of the structure, while increasing Aj reduces the buckling effect, resulting in a higher specific energy absorption and lower ultimate load capacity for the BCT compared to the CCT and LCT. A simultaneous multi-objective optimization of the CCT, LCT, and BCT confirms that the BCT offers superior specific energy absorption and ultimate load capacity. The optimal configuration parameters for the BCT have been determined, providing significant insights for practical applications in crashworthiness engineering.","PeriodicalId":503043,"journal":{"name":"Materials","volume":"52 13","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-08-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141922941","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}
I. Antoniac, Niculae Valeanu, Marius Niculescu, A. Antoniac, Alina Robu, Larisa Popescu, Veronica Manescu (Paltanea), Dan Anusca, Catalin Ionel Enachescu
This research aims to identify the prevalence of failure for Birmingham Hip Prosthesis (BHR) in total hip arthroplasty and to analyze its reasons from biomaterials and biofunctional perspectives. We present our current analysis and tests on a series of different BHR-retrieved prostheses after premature failure. Relevant clinical data, such as X-ray investigations and intraoperative images for clinical case studies, were analyzed to better understand all factors involved in BHR prosthesis failure. A detailed analysis of the failures highlighted uneven cement distribution, overloading in certain areas, and void formation in the material. A closer investigation using microscopical techniques revealed the presence of a crack originating from the gap between the cement mantle and human bone. Additionally, scanning electron microscopy analyses were conducted as part of the investigation to examine bone cement morphology in detail and better understand the interactions at the interfaces between implant, cement, and bone. In conclusion, this research emphasizes the importance of surgical technique planning and the cementation procedure in the success rate of BHR prostheses. It also underscores the need to carefully evaluate patient characteristics and bone quality to minimize the risk of BHR prosthesis failure. The cementation procedure seems to be essential for the long-term functionality of the BHR prosthesis.
{"title":"Outcomes of Birmingham Hip Resurfacing Based on Clinical Aspects and Retrieval Analysis of Failed Prosthesis","authors":"I. Antoniac, Niculae Valeanu, Marius Niculescu, A. Antoniac, Alina Robu, Larisa Popescu, Veronica Manescu (Paltanea), Dan Anusca, Catalin Ionel Enachescu","doi":"10.3390/ma17163965","DOIUrl":"https://doi.org/10.3390/ma17163965","url":null,"abstract":"This research aims to identify the prevalence of failure for Birmingham Hip Prosthesis (BHR) in total hip arthroplasty and to analyze its reasons from biomaterials and biofunctional perspectives. We present our current analysis and tests on a series of different BHR-retrieved prostheses after premature failure. Relevant clinical data, such as X-ray investigations and intraoperative images for clinical case studies, were analyzed to better understand all factors involved in BHR prosthesis failure. A detailed analysis of the failures highlighted uneven cement distribution, overloading in certain areas, and void formation in the material. A closer investigation using microscopical techniques revealed the presence of a crack originating from the gap between the cement mantle and human bone. Additionally, scanning electron microscopy analyses were conducted as part of the investigation to examine bone cement morphology in detail and better understand the interactions at the interfaces between implant, cement, and bone. In conclusion, this research emphasizes the importance of surgical technique planning and the cementation procedure in the success rate of BHR prostheses. It also underscores the need to carefully evaluate patient characteristics and bone quality to minimize the risk of BHR prosthesis failure. The cementation procedure seems to be essential for the long-term functionality of the BHR prosthesis.","PeriodicalId":503043,"journal":{"name":"Materials","volume":"50 20","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-08-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141923806","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}
Yuchen Zhang, Dayong Yang, Lingxin Zeng, Zhiyang Zhang, Shuping Li
Powder metallurgy (PM) technology is extensively employed in the manufacturing sector, yet its processing presents numerous challenges. To alleviate these difficulties, green machining of PM green compacts has emerged as an effective approach. The aim of this research is to explore the deformation features of green compacts and assess the impact of various machining parameters on the force of cutting. The cutting variables for compacts of PM green were modeled, and the cutting process was analyzed using Abaqus (2022) software. Subsequently, the orthogonal test ANOVA method was utilized to evaluate the significance of each parameter for the cutting force. Optimization of the machining parameters was then achieved through a genetic algorithm for neural network optimization. The investigation revealed that PM green compacts, which are brittle, undergo a plastic deformation stage during cutting and deviate from the traditional model for brittle materials. The findings indicate that cutting thickness exerts the most substantial influence on the cutting force, whereas the speed of cutting, the tool rake angle, and the radius of the rounded edge exert minimal influence. The optimal parameter combination for the cutting of PM green compacts was determined via a genetic algorithm for neural network optimization, yielding a cutting force of 174.998 N at a cutting thickness of 0.15 mm, a cutting speed of 20 m/min, a tool rake angle of 10°, and a radius of the rounded edge of 25 μm, with a discrepancy of 4.05% from the actual measurement.
{"title":"Simulation and Algorithmic Optimization of the Cutting Process for the Green Machining of PM Green Compacts","authors":"Yuchen Zhang, Dayong Yang, Lingxin Zeng, Zhiyang Zhang, Shuping Li","doi":"10.3390/ma17163963","DOIUrl":"https://doi.org/10.3390/ma17163963","url":null,"abstract":"Powder metallurgy (PM) technology is extensively employed in the manufacturing sector, yet its processing presents numerous challenges. To alleviate these difficulties, green machining of PM green compacts has emerged as an effective approach. The aim of this research is to explore the deformation features of green compacts and assess the impact of various machining parameters on the force of cutting. The cutting variables for compacts of PM green were modeled, and the cutting process was analyzed using Abaqus (2022) software. Subsequently, the orthogonal test ANOVA method was utilized to evaluate the significance of each parameter for the cutting force. Optimization of the machining parameters was then achieved through a genetic algorithm for neural network optimization. The investigation revealed that PM green compacts, which are brittle, undergo a plastic deformation stage during cutting and deviate from the traditional model for brittle materials. The findings indicate that cutting thickness exerts the most substantial influence on the cutting force, whereas the speed of cutting, the tool rake angle, and the radius of the rounded edge exert minimal influence. The optimal parameter combination for the cutting of PM green compacts was determined via a genetic algorithm for neural network optimization, yielding a cutting force of 174.998 N at a cutting thickness of 0.15 mm, a cutting speed of 20 m/min, a tool rake angle of 10°, and a radius of the rounded edge of 25 μm, with a discrepancy of 4.05% from the actual measurement.","PeriodicalId":503043,"journal":{"name":"Materials","volume":"19 14","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-08-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141925297","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}
Md Abu Jafor, Neshat Sayah, Douglas E. Smith, G. Stano, Trevor J. Fleck
Material extrusion (MEX) additive manufacturing has successfully fabricated assembly-free structures composed of different materials processed in the same manufacturing cycle. Materials with different mechanical properties can be employed for the fabrication of bio-inspired structures (i.e., stiff materials connected to soft materials), which are appealing for many fields, such as bio-medical and soft robotics. In the present paper, process parameters and 3D printing strategies are presented to improve the interfacial adhesion between carbon fiber-reinforced nylon (CFPA) and thermoplastic polyurethane (TPU), which are extruded in the same manufacturing cycle using a multi-material MEX setup. To achieve our goal, a double cantilever beam (DCB) test was used to evaluate the mode I fracture toughness. The results show that the application of a heating gun (assembled near the nozzle) provides a statistically significant increase in mean fracture toughness energy from 12.3 kJ/m2 to 33.4 kJ/m2. The underlying mechanism driving this finding was further investigated by quantifying porosity at the multi-material interface using an X-ray computed tomography (CT) system, in addition to quantifying thermal history. The results show that using both bead ironing and the hot air gun during the printing process leads to a reduction of 24% in the average void volume fraction. The findings from the DCB test and X-ray CT analysis agree well with the polymer healing theory, in which an increased thermal history led to an increased fracture toughness at the multi-material interface. Moreover, this study considers the thermal history of each printed layer to correlate the measured debonding energy with results obtained using the reptation theory.
材料挤压（MEX）增材制造技术成功地制造出了由在同一制造周期内加工的不同材料组成的无装配结构。具有不同机械特性的材料可用于制造生物启发结构（即刚性材料与软性材料连接），这对生物医学和软机器人等许多领域都很有吸引力。本文介绍了改善碳纤维增强尼龙（CFPA）和热塑性聚氨酯（TPU）之间界面粘附性的工艺参数和三维打印策略。为了实现我们的目标，我们采用了双悬臂梁（DCB）试验来评估模态 I 断裂韧性。结果表明，应用加热枪（装配在喷嘴附近）可使平均断裂韧性能量从 12.3 kJ/m2 显著增加到 33.4 kJ/m2。通过使用 X 射线计算机断层扫描（CT）系统对多材料界面的孔隙率进行量化，并对热历史进行量化，进一步研究了这一发现的内在机理。结果表明，在印刷过程中使用珠熨和热风枪可使平均空隙体积分数减少 24%。DCB 测试和 X 射线 CT 分析的结果与聚合物愈合理论十分吻合，即热历史的增加会导致多材料界面断裂韧性的增加。此外，本研究还考虑了每个印刷层的热历史，从而将测得的脱粘能量与使用跃迁理论得出的结果联系起来。
{"title":"Systematic Evaluation of Adhesion and Fracture Toughness in Multi-Material Fused Deposition Material Extrusion","authors":"Md Abu Jafor, Neshat Sayah, Douglas E. Smith, G. Stano, Trevor J. Fleck","doi":"10.3390/ma17163953","DOIUrl":"https://doi.org/10.3390/ma17163953","url":null,"abstract":"Material extrusion (MEX) additive manufacturing has successfully fabricated assembly-free structures composed of different materials processed in the same manufacturing cycle. Materials with different mechanical properties can be employed for the fabrication of bio-inspired structures (i.e., stiff materials connected to soft materials), which are appealing for many fields, such as bio-medical and soft robotics. In the present paper, process parameters and 3D printing strategies are presented to improve the interfacial adhesion between carbon fiber-reinforced nylon (CFPA) and thermoplastic polyurethane (TPU), which are extruded in the same manufacturing cycle using a multi-material MEX setup. To achieve our goal, a double cantilever beam (DCB) test was used to evaluate the mode I fracture toughness. The results show that the application of a heating gun (assembled near the nozzle) provides a statistically significant increase in mean fracture toughness energy from 12.3 kJ/m2 to 33.4 kJ/m2. The underlying mechanism driving this finding was further investigated by quantifying porosity at the multi-material interface using an X-ray computed tomography (CT) system, in addition to quantifying thermal history. The results show that using both bead ironing and the hot air gun during the printing process leads to a reduction of 24% in the average void volume fraction. The findings from the DCB test and X-ray CT analysis agree well with the polymer healing theory, in which an increased thermal history led to an increased fracture toughness at the multi-material interface. Moreover, this study considers the thermal history of each printed layer to correlate the measured debonding energy with results obtained using the reptation theory.","PeriodicalId":503043,"journal":{"name":"Materials","volume":"12 22","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-08-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141925124","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}
Anja Terzić, J. Stojanović, V. Jovanović, Dejan Todorović, Miroslav Sokić, D. Bojović, Dragan Radulović
The presented work offers an innovative process scheme for valorizing Pb-Zn slag, which involves crushing, grinding, and separation techniques to concentrate valuable components (non-ferrous metals). This methodology could have a significant impact on the global beneficiation of metallurgical slags since it is significantly more simple, environmentally friendly, and cost-effective than standard pyro- and hydrometallurgical procedures. According to previous physicochemical and mineralogical studies, Pb-Zn slag is a valuable secondary raw material. This inhomogeneous technogenic resource contains substantial amounts of non-ferrous metals (Pb, Zn, Cu, and Ag). However, laboratory tests have indicated that the Pb-Zn slag contains highly uneven amounts of valuable metals, ranging from several g/ton to tens of g/ton. The main issue is that traditional metallurgical procedures for releasing beneficial elements are not commercially viable since the elements are “trapped” within the amorphous aluminosilicates or intergrowths of alloy grains and glassy phases. Gravity concentration (Wilfley 13 shaking table) and magnetic separation (Davis separator and disk separator) were used to obtain the final concentrate following comminution and grindability testing. The gravity concentration proved more effective. Namely, magnetic separators could not process nor adequately separate beneficial non-ferrous elements because they were merged together with iron-bearing minerals and aluminosilicates in amorphous Pb-Zn slag grains. With the gravity concentration approach, 12.99% of the processed slag belonged to ∆T fraction (concentration of non-ferrous metal alloys), while remaining 87% corresponded to the tailings fraction (∆L). The total amounts of recovered Pb, Zn, Cu, and Ag from ∆T and ∆L fractions were 5.28%, 6.69%, 0.58%, and 76.12 ppm and 1.22%, 6.05%, 0.43%, and 15.26 ppm, respectively. This streamlined approach to valorizing Pb-Zn slag can reduce the need for hazardous chemicals used in hydrometallurgical refinement operations, as well as the extremely high temperatures required for pyrometallurgical processing. This is the first study to investigate the viability of this novel methodology, which involves the direct examinations of the Pb-Zn slag feed with various alternative technologies for separation and concentration. After extracting the valuable metals, the amorphous aluminosilicate part of the Pb-Zn slag can be reapplied as an alternative raw material in the building sector, adding to the circularity of the suggested approach.
{"title":"Exploring the Efficiency of Magnetic Separation and Gravity Concentration for Valorizing Pb-Zn Smelter Slag in a Circular Economy Framework","authors":"Anja Terzić, J. Stojanović, V. Jovanović, Dejan Todorović, Miroslav Sokić, D. Bojović, Dragan Radulović","doi":"10.3390/ma17163945","DOIUrl":"https://doi.org/10.3390/ma17163945","url":null,"abstract":"The presented work offers an innovative process scheme for valorizing Pb-Zn slag, which involves crushing, grinding, and separation techniques to concentrate valuable components (non-ferrous metals). This methodology could have a significant impact on the global beneficiation of metallurgical slags since it is significantly more simple, environmentally friendly, and cost-effective than standard pyro- and hydrometallurgical procedures. According to previous physicochemical and mineralogical studies, Pb-Zn slag is a valuable secondary raw material. This inhomogeneous technogenic resource contains substantial amounts of non-ferrous metals (Pb, Zn, Cu, and Ag). However, laboratory tests have indicated that the Pb-Zn slag contains highly uneven amounts of valuable metals, ranging from several g/ton to tens of g/ton. The main issue is that traditional metallurgical procedures for releasing beneficial elements are not commercially viable since the elements are “trapped” within the amorphous aluminosilicates or intergrowths of alloy grains and glassy phases. Gravity concentration (Wilfley 13 shaking table) and magnetic separation (Davis separator and disk separator) were used to obtain the final concentrate following comminution and grindability testing. The gravity concentration proved more effective. Namely, magnetic separators could not process nor adequately separate beneficial non-ferrous elements because they were merged together with iron-bearing minerals and aluminosilicates in amorphous Pb-Zn slag grains. With the gravity concentration approach, 12.99% of the processed slag belonged to ∆T fraction (concentration of non-ferrous metal alloys), while remaining 87% corresponded to the tailings fraction (∆L). The total amounts of recovered Pb, Zn, Cu, and Ag from ∆T and ∆L fractions were 5.28%, 6.69%, 0.58%, and 76.12 ppm and 1.22%, 6.05%, 0.43%, and 15.26 ppm, respectively. This streamlined approach to valorizing Pb-Zn slag can reduce the need for hazardous chemicals used in hydrometallurgical refinement operations, as well as the extremely high temperatures required for pyrometallurgical processing. This is the first study to investigate the viability of this novel methodology, which involves the direct examinations of the Pb-Zn slag feed with various alternative technologies for separation and concentration. After extracting the valuable metals, the amorphous aluminosilicate part of the Pb-Zn slag can be reapplied as an alternative raw material in the building sector, adding to the circularity of the suggested approach.","PeriodicalId":503043,"journal":{"name":"Materials","volume":"11 11","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141925925","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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