The existence of joints or other kinds of discontinuities has a dramatic efect on the stability of rock excavations and engineering.As a result,a great challenge in rock mass mechanics testing is to prepare rock or ro...The existence of joints or other kinds of discontinuities has a dramatic efect on the stability of rock excavations and engineering.As a result,a great challenge in rock mass mechanics testing is to prepare rock or rock-like samples with defects.In recent years,3D printing technology has become a promising tool in the feld of rock mass mechanics and engineering.This study frst reviews and discusses the research status of traditional test methods in rock mass mechanics tests of making rock samples with defects.Then,based on the comprehensive analysis of previous research,the application of 3D printing technology in rock mass mechanics is expounded from the following three aspects.The frst is the printing material.Although there are many materials for 3D printing,it has been found that 3D printing materials that can be used for rock mass mechanics research are very limited.After research,we summarize and evaluate printing material that can be used for rock mass mechanics studies.The second is the printing methodology,which mainly introduces the current application forms of 3D printing technology in rock mass mechanics.This includes printed precise casting molds and one-time printed samples.The last one is the printing model,which includes small-scale samples for mechanical tests and large-scale physical models.Then,the benefts and drawbacks of using 3D printing samples in mechanical tests and the validity of their simulation of real rock are discussed.Compared with traditional rock samples collected in nature or synthetic rock-like samples,the samples made by 3D printing technology have unique advantages,such as higher test repeatability,visualization of rock internal structure and stress distribution.There is thus great potential for the use of 3D printing in the feld of rock mass mechanics.However,3D printing materials also have shortcomings,such as insufcient material strength and accuracy at this stage.Finally,the application prospect of 3D printing technology in rock mass mechanics research is proposed.展开更多
Electron beam welding （EBW） is a fusion welding process in which a beam of high-velocity electrons is applied to two materials to be joined. It is a complex high-temperature metallurgical process, and the quality of...Electron beam welding （EBW） is a fusion welding process in which a beam of high-velocity electrons is applied to two materials to be joined. It is a complex high-temperature metallurgical process, and the quality of welding may deteriorate because of defects caused by improper welding parameters, especially in the EBW of thickened aluminum alloy plate. Ultrasonic phased array（UPA） technology has been applied more widely in the field of nondestructive testing because of its ability of effectively controlling the shape and direction of the emitted ultrasonic beam. In present research, a specimen with EBW seam on thickened aluminum plate was tested with a linear array ultrasonic phased array probe, and a large number of B-scan images of the weld were acquired by electronic scanning in probe combined with the mechanical scanning of the probe along the weld direction. This large number of B-scan images were stacked to construct the volume data, with which the 3D image of the weld discontinuities were reconstructed, and the 3D visualization was realized. More details about weld discontinuities＇ spatial distribution and orientation were revealed, and this approach also made the results of non-destructive ultrasonic testing more easily to understand.展开更多
Recently,3D concrete printing(3DCP)technology starts entering the market from factories and laboratories,contributing to the creation of new construction methods and architectural forms.However,since the technologies ...Recently,3D concrete printing(3DCP)technology starts entering the market from factories and laboratories,contributing to the creation of new construction methods and architectural forms.However,since the technologies of most 3DCP institutions are independently developed,there is a lack of consensus in terms of construction methods and development approaches in the industry.In this paper,based on 423DCP architectural works completed in last five years,a quantitative analysis was made to evaluate the impacts of the fabrication system on 3DCP building forms.The paper introduced three criteria,including Workspace Index,Geometric Complexity Index,and Tectonic Prospect Index,analyzing and answering the discussions about"adopting in-situ printing or prefabrication","using gantry printers or robotic arms"from the perspective of architectural form.By analyzing specific construction methods and design strategies in these projects,the research summarized three development trends,"mobile equipment,algorithmic structure,and intelligent construction",which will affect the future development of 3DCP building forms.Finally,the paper discussed the advantages,limitations,and potential of four different 3DCP fabrication systems,expecting to point out the directions to further optimize each system and realize more diverse 3DCP buildings.展开更多
基金the National Natural Science Foundation of China(52074166)Shandong Province(ZR2021YQ38)the Open Grant of State Key Laboratory of Mining Response and Disaster Prevention and Control in Deep Coal Mines(SKLMRDPC20KF02).
文摘The existence of joints or other kinds of discontinuities has a dramatic efect on the stability of rock excavations and engineering.As a result,a great challenge in rock mass mechanics testing is to prepare rock or rock-like samples with defects.In recent years,3D printing technology has become a promising tool in the feld of rock mass mechanics and engineering.This study frst reviews and discusses the research status of traditional test methods in rock mass mechanics tests of making rock samples with defects.Then,based on the comprehensive analysis of previous research,the application of 3D printing technology in rock mass mechanics is expounded from the following three aspects.The frst is the printing material.Although there are many materials for 3D printing,it has been found that 3D printing materials that can be used for rock mass mechanics research are very limited.After research,we summarize and evaluate printing material that can be used for rock mass mechanics studies.The second is the printing methodology,which mainly introduces the current application forms of 3D printing technology in rock mass mechanics.This includes printed precise casting molds and one-time printed samples.The last one is the printing model,which includes small-scale samples for mechanical tests and large-scale physical models.Then,the benefts and drawbacks of using 3D printing samples in mechanical tests and the validity of their simulation of real rock are discussed.Compared with traditional rock samples collected in nature or synthetic rock-like samples,the samples made by 3D printing technology have unique advantages,such as higher test repeatability,visualization of rock internal structure and stress distribution.There is thus great potential for the use of 3D printing in the feld of rock mass mechanics.However,3D printing materials also have shortcomings,such as insufcient material strength and accuracy at this stage.Finally,the application prospect of 3D printing technology in rock mass mechanics research is proposed.
基金supported by the National Natural Science Foundation of China(Grant No.51575134 and 51175113)
文摘Electron beam welding （EBW） is a fusion welding process in which a beam of high-velocity electrons is applied to two materials to be joined. It is a complex high-temperature metallurgical process, and the quality of welding may deteriorate because of defects caused by improper welding parameters, especially in the EBW of thickened aluminum alloy plate. Ultrasonic phased array（UPA） technology has been applied more widely in the field of nondestructive testing because of its ability of effectively controlling the shape and direction of the emitted ultrasonic beam. In present research, a specimen with EBW seam on thickened aluminum plate was tested with a linear array ultrasonic phased array probe, and a large number of B-scan images of the weld were acquired by electronic scanning in probe combined with the mechanical scanning of the probe along the weld direction. This large number of B-scan images were stacked to construct the volume data, with which the 3D image of the weld discontinuities were reconstructed, and the 3D visualization was realized. More details about weld discontinuities＇ spatial distribution and orientation were revealed, and this approach also made the results of non-destructive ultrasonic testing more easily to understand.
基金the National Natural Science Foundation of China(Project No.51538006).
文摘Recently,3D concrete printing(3DCP)technology starts entering the market from factories and laboratories,contributing to the creation of new construction methods and architectural forms.However,since the technologies of most 3DCP institutions are independently developed,there is a lack of consensus in terms of construction methods and development approaches in the industry.In this paper,based on 423DCP architectural works completed in last five years,a quantitative analysis was made to evaluate the impacts of the fabrication system on 3DCP building forms.The paper introduced three criteria,including Workspace Index,Geometric Complexity Index,and Tectonic Prospect Index,analyzing and answering the discussions about"adopting in-situ printing or prefabrication","using gantry printers or robotic arms"from the perspective of architectural form.By analyzing specific construction methods and design strategies in these projects,the research summarized three development trends,"mobile equipment,algorithmic structure,and intelligent construction",which will affect the future development of 3DCP building forms.Finally,the paper discussed the advantages,limitations,and potential of four different 3DCP fabrication systems,expecting to point out the directions to further optimize each system and realize more diverse 3DCP buildings.
