Metal additive manufacturing(AM)holds significant potential for the rapid prototyping of complex parts in the aerospace,defense,and military industries,biomedicine,and other fields.Despite its advantages over conventi...Metal additive manufacturing(AM)holds significant potential for the rapid prototyping of complex parts in the aerospace,defense,and military industries,biomedicine,and other fields.Despite its advantages over conventional manufacturing methods,AM faces technical bottlenecks(e.g.,poor densification,high residual stress,and significant anisotropy of mechanical properties),which hinder its large-scale industrial application.The newly emerging metal hybrid additive manufacturing(MHAM)serves as a viable approach to address the inherent issues associated with AM.This method integrates different auxiliary technologies(e.g.,subtractive manufacturing,formative manufacturing,magnetic fields,ultrasonic fields,thermal fields,etc.),leveraging the strengths of these technologies to enhance the performance of metal components produced via AM.MHAM offers numerous advantages,such as controlling the flow of the melt pool,refining the microstructure,optimizing the grain size orientation,reducing the residual stress,enhancing the surface quality,and improving the mechanical properties and fatigue resistance.This work offers a thorough and current analysis of the state of MHAM development,including additive and subtractive hybrid manufacturing,additive and formative hybrid manufacturing,and energy field-assisted additive manufacturing.It delineates the MHAM technology framework and clarifies the interaction mechanisms among various auxiliary technologies used in AM.Additionally,it discusses the impacts of MHAM on melt pool dynamics,solidification processes,densification,microstructure evolution,surface quality,and mechanical and fatigue properties.In summary,the distinct characteristics of various MHAM techniques are outlined,and future trends in MHAM development are anticipated.展开更多
The 2.5D process is widely utilized in modern industries,with multi-genus cross-sections increasingly encountered in both additive and subtractive manufacturing.Tool paths for multigenus shapes often suffer from disco...The 2.5D process is widely utilized in modern industries,with multi-genus cross-sections increasingly encountered in both additive and subtractive manufacturing.Tool paths for multigenus shapes often suffer from discontinuities that lead to frequent tool liftings,and selfintersections in offset paths,adversely affecting machining accuracy and efficiency.In this context,path topology,stepover uniformity,and degeneration of offset paths represent three fundamental concerns that must be considered in an integrated manner in 2.5D path planning for multi-genus shapes.This study proposes a tool path planning method based on combining of topological and geometric characteristics of medial axis transformation for the shape with multi-genus.A region segmentation strategy tailored to multi-genus shapes is first introduced to prevent global selfintersections in equidistant offset paths.Subsequently,the graph structure of the segmented shape is extracted,and the minimization of tool liftings is formulated as a minimum path cover problem in an undirected graph.A Fermat-spiral-like path topology is adopted within sub-regions to preserve the connectivity of graph and ensure smooth transitions between successive layers of contourparallel paths.Numerical and physical experiment results confirm the proposed method's effectiveness in maintaining stepover uniformity,avoiding degeneration of global self-intersections,and ensuring path connectivity.展开更多
Conformal truss-like lattice structures face significant manufacturability challenges in additive manufac-turing due to overhang angle limitations.To address this problem,we propose a novel angle-constrained optimizat...Conformal truss-like lattice structures face significant manufacturability challenges in additive manufac-turing due to overhang angle limitations.To address this problem,we propose a novel angle-constrained optimization method grounded in the global adjustment of nodal coordinates.First,a build direction is selected to minimize the number of violating struts.Then,an angular-constraint matrix is assembled from strut direction vectors,and analytical sensitivities with respect to nodal coordinates are derived to enable efficient constrained optimization under nonlinear angular inequality constraints.Numerical studies on two complex curved-surface lattices demonstrate that all overhang violations are eliminated while only minor changes are induced in global stiffness and strength.In particular,the maximum displacement of an ergonomic insole varies by only 2.87%after optimization.The results confirm the method’s versatility and engineering robustness,providing a practical approach for additive manufacturing-oriented lattice structure design.展开更多
基金supported by the“Intelligent Manufacturing”Science and Technology Major Project of Shaanxi Province(Grant Number 2019zdzx01-04-02).
摘要Metal additive manufacturing(AM)holds significant potential for the rapid prototyping of complex parts in the aerospace,defense,and military industries,biomedicine,and other fields.Despite its advantages over conventional manufacturing methods,AM faces technical bottlenecks(e.g.,poor densification,high residual stress,and significant anisotropy of mechanical properties),which hinder its large-scale industrial application.The newly emerging metal hybrid additive manufacturing(MHAM)serves as a viable approach to address the inherent issues associated with AM.This method integrates different auxiliary technologies(e.g.,subtractive manufacturing,formative manufacturing,magnetic fields,ultrasonic fields,thermal fields,etc.),leveraging the strengths of these technologies to enhance the performance of metal components produced via AM.MHAM offers numerous advantages,such as controlling the flow of the melt pool,refining the microstructure,optimizing the grain size orientation,reducing the residual stress,enhancing the surface quality,and improving the mechanical properties and fatigue resistance.This work offers a thorough and current analysis of the state of MHAM development,including additive and subtractive hybrid manufacturing,additive and formative hybrid manufacturing,and energy field-assisted additive manufacturing.It delineates the MHAM technology framework and clarifies the interaction mechanisms among various auxiliary technologies used in AM.Additionally,it discusses the impacts of MHAM on melt pool dynamics,solidification processes,densification,microstructure evolution,surface quality,and mechanical and fatigue properties.In summary,the distinct characteristics of various MHAM techniques are outlined,and future trends in MHAM development are anticipated.
基金supported by the Beijing Natural Science Foundation,China(No.Z240002)the National Natural Science Foundation of China(Nos.62102013,12171023,and 12001028)。
摘要The 2.5D process is widely utilized in modern industries,with multi-genus cross-sections increasingly encountered in both additive and subtractive manufacturing.Tool paths for multigenus shapes often suffer from discontinuities that lead to frequent tool liftings,and selfintersections in offset paths,adversely affecting machining accuracy and efficiency.In this context,path topology,stepover uniformity,and degeneration of offset paths represent three fundamental concerns that must be considered in an integrated manner in 2.5D path planning for multi-genus shapes.This study proposes a tool path planning method based on combining of topological and geometric characteristics of medial axis transformation for the shape with multi-genus.A region segmentation strategy tailored to multi-genus shapes is first introduced to prevent global selfintersections in equidistant offset paths.Subsequently,the graph structure of the segmented shape is extracted,and the minimization of tool liftings is formulated as a minimum path cover problem in an undirected graph.A Fermat-spiral-like path topology is adopted within sub-regions to preserve the connectivity of graph and ensure smooth transitions between successive layers of contourparallel paths.Numerical and physical experiment results confirm the proposed method's effectiveness in maintaining stepover uniformity,avoiding degeneration of global self-intersections,and ensuring path connectivity.
基金supported by the National Natural Science Foundation of China(Grant Nos.12432005 and 12472116)the Fundamental Research Funds for the Central Universities(DUTZD25240).
摘要Conformal truss-like lattice structures face significant manufacturability challenges in additive manufac-turing due to overhang angle limitations.To address this problem,we propose a novel angle-constrained optimization method grounded in the global adjustment of nodal coordinates.First,a build direction is selected to minimize the number of violating struts.Then,an angular-constraint matrix is assembled from strut direction vectors,and analytical sensitivities with respect to nodal coordinates are derived to enable efficient constrained optimization under nonlinear angular inequality constraints.Numerical studies on two complex curved-surface lattices demonstrate that all overhang violations are eliminated while only minor changes are induced in global stiffness and strength.In particular,the maximum displacement of an ergonomic insole varies by only 2.87%after optimization.The results confirm the method’s versatility and engineering robustness,providing a practical approach for additive manufacturing-oriented lattice structure design.