Polymeric biomaterials such as polylactic acid(PLA)play a prominent role in the advancement of biomedical additive manufacturing(AM).PLA offers indeed a very advantageous combination of thermomechanical properties and...Polymeric biomaterials such as polylactic acid(PLA)play a prominent role in the advancement of biomedical additive manufacturing(AM).PLA offers indeed a very advantageous combination of thermomechanical properties and functional attributes,as it is biobased,biodegradable,biocompatible and easy to print.However,PLA can be damaged by common sterilization methods and is sensitive to most chemical disinfectants,and this may impair its widespread usage.One of the most promising ways to overcome this shortcoming is to provide PLA with embedded antibacterial activity by the addition of appropriate fillers such as zinc oxide(Zn O)nanoparticles.After a detailed introduction to the basic properties of PLA and ZnO nanoparticles,the present review analyzes the main variables that govern the antibacterial activity of PLA-ZnO nanocomposites.Current applications and related manufacturing processes are also presented to showcase the importance of having embedded antibacterial functions in demanding applications such as food packaging and wound dressing.Emphasis is then placed on the emerging literature of the AM of PLA-ZnO nanocomposites,with a focus on fused filament fabrication(also known as fused deposition modeling).Existing gaps and hurdles related to the development and 3D printing of such composites is critically discussed.It is envisioned that a deeper understanding of the processability,thermo-mechanical behavior,biocompatibility and antibacterial efficacy of additively manufactured PLAZnO nanocomposites will foster their adoption in the biomedical field and,ultimately,in all circumstances where it is crucial to limit infection transmission.展开更多
Prior to the application of AM components for critical applications,it is necessary to have a better understanding of the effect of different post-fabrication treatments on the microstructure and mechanical properties...Prior to the application of AM components for critical applications,it is necessary to have a better understanding of the effect of different post-fabrication treatments on the microstructure and mechanical properties of such parts.In this study,efforts were made to achieve an in-depth understanding of the effect of post-fabrication Solution Heat Treatment(SHT)and Hot Isostatic Pressing(HIP)on the microstructure and mechanical properties of Hastelloy X parts built by electron beam powder bed fusion(PBF-EB)process.The effects of SHT and HIP on porosity,microstructure,texture and mechanical properties have been investigated and compared with that of as-built PBF-EB Hastelloy X.Post-fabrication HIP treatment led to a significant reduction in the porosity content,whereas no notable difference in porosity was observed between SHT and as-built parts.There was no evidence of any recrystallization occurring following the post-fabrication treatments as elongated columnar grain structures observed within as-built part were found to be maintained even after SHT and HIP process alongside the strong<100>crystallographic texture.Emphasis was laid upon understanding the influence of SHT and HIP on mechanical properties through stress-strain curves and work-hardening behaviour.展开更多
Finding a basis of unification for the modeling of mechatronic systems is the search subject of several works.This paper is a part of a general research designed to the application of topology as a new approach for th...Finding a basis of unification for the modeling of mechatronic systems is the search subject of several works.This paper is a part of a general research designed to the application of topology as a new approach for the modeling of mechatronic systems.Particularly,the modeling of a one stage spur gear transmission using a topological approach is tackled.This approach is based on the concepts of topological collections and transformations and implemented using the MGS（modeling of general systems）language.The topological collections are used to specify the interconnection laws of the one stage spur gear transmission and the transformations are used to specify the local behavior laws of its different components.In order to validate this approach,simulation results are presented and compared with those obtained with MODELICA language using Dymola solver.Since good results are achieved,this approach might be used as a basis of unification for the modeling of mechatronic systems.展开更多
This paper presents a combination method of Particle Swarm Optimization (PSO) and topology optimization. With this method a better result can be achieved compared with the sequential application of these two optimizat...This paper presents a combination method of Particle Swarm Optimization (PSO) and topology optimization. With this method a better result can be achieved compared with the sequential application of these two optimization methods. It inherits the ability in finding global optimum from PSO and also suits for discretized design domain. Some special schemes are used in order to provide higher computation efficiency. This method has only been tested with a convex optimization problem. The application in case of a concave problem will be a future study.展开更多
基金supported by the Australian Research Council(ARC)through the discovery grant DP210101862supported by the Commonwealth Scientific and Industrial Research Organisation(CSIRO)Research Office through the“Science Leader in Active Materials”grant。
文摘Polymeric biomaterials such as polylactic acid(PLA)play a prominent role in the advancement of biomedical additive manufacturing(AM).PLA offers indeed a very advantageous combination of thermomechanical properties and functional attributes,as it is biobased,biodegradable,biocompatible and easy to print.However,PLA can be damaged by common sterilization methods and is sensitive to most chemical disinfectants,and this may impair its widespread usage.One of the most promising ways to overcome this shortcoming is to provide PLA with embedded antibacterial activity by the addition of appropriate fillers such as zinc oxide(Zn O)nanoparticles.After a detailed introduction to the basic properties of PLA and ZnO nanoparticles,the present review analyzes the main variables that govern the antibacterial activity of PLA-ZnO nanocomposites.Current applications and related manufacturing processes are also presented to showcase the importance of having embedded antibacterial functions in demanding applications such as food packaging and wound dressing.Emphasis is then placed on the emerging literature of the AM of PLA-ZnO nanocomposites,with a focus on fused filament fabrication(also known as fused deposition modeling).Existing gaps and hurdles related to the development and 3D printing of such composites is critically discussed.It is envisioned that a deeper understanding of the processability,thermo-mechanical behavior,biocompatibility and antibacterial efficacy of additively manufactured PLAZnO nanocomposites will foster their adoption in the biomedical field and,ultimately,in all circumstances where it is crucial to limit infection transmission.
文摘Prior to the application of AM components for critical applications,it is necessary to have a better understanding of the effect of different post-fabrication treatments on the microstructure and mechanical properties of such parts.In this study,efforts were made to achieve an in-depth understanding of the effect of post-fabrication Solution Heat Treatment(SHT)and Hot Isostatic Pressing(HIP)on the microstructure and mechanical properties of Hastelloy X parts built by electron beam powder bed fusion(PBF-EB)process.The effects of SHT and HIP on porosity,microstructure,texture and mechanical properties have been investigated and compared with that of as-built PBF-EB Hastelloy X.Post-fabrication HIP treatment led to a significant reduction in the porosity content,whereas no notable difference in porosity was observed between SHT and as-built parts.There was no evidence of any recrystallization occurring following the post-fabrication treatments as elongated columnar grain structures observed within as-built part were found to be maintained even after SHT and HIP process alongside the strong<100>crystallographic texture.Emphasis was laid upon understanding the influence of SHT and HIP on mechanical properties through stress-strain curves and work-hardening behaviour.
文摘Finding a basis of unification for the modeling of mechatronic systems is the search subject of several works.This paper is a part of a general research designed to the application of topology as a new approach for the modeling of mechatronic systems.Particularly,the modeling of a one stage spur gear transmission using a topological approach is tackled.This approach is based on the concepts of topological collections and transformations and implemented using the MGS（modeling of general systems）language.The topological collections are used to specify the interconnection laws of the one stage spur gear transmission and the transformations are used to specify the local behavior laws of its different components.In order to validate this approach,simulation results are presented and compared with those obtained with MODELICA language using Dymola solver.Since good results are achieved,this approach might be used as a basis of unification for the modeling of mechatronic systems.
文摘This paper presents a combination method of Particle Swarm Optimization (PSO) and topology optimization. With this method a better result can be achieved compared with the sequential application of these two optimization methods. It inherits the ability in finding global optimum from PSO and also suits for discretized design domain. Some special schemes are used in order to provide higher computation efficiency. This method has only been tested with a convex optimization problem. The application in case of a concave problem will be a future study.
