Thin-walled aerostructural components frequently get distorted after the machining process.Reworking to correct distortions or eventually rejecting parts significantly increases the cost.This paper proposes a new appr...Thin-walled aerostructural components frequently get distorted after the machining process.Reworking to correct distortions or eventually rejecting parts significantly increases the cost.This paper proposes a new approach to correct distortions in thin-walled components by strategically applying hammer peening on target surfaces of a machined component.Aluminium alloy 7475-T7351 was chosen for this research.The study was divided in two stages.First,the residual stresses(RS)induced by four different pneumatic hammer peening conditions(modifying the stepover distance and initial offset)were characterised in a test coupon,and one of the conditions was selected for the next stage.In the second stage,a FEM model was used to predict distortions caused by machining in a representative workpiece.Then,the RS induced by hammer peening were included in an FEM model to define two hammer peening strategies(varying the coverage area)to analyse the capability to reduce distortions.Two workpieces were machined and then treated with the simulated hammer peening strategies for experimental validation.Results in the test coupon showed that pneumatic hammer peening can generate high compressive RS(-50 to350 MPa)up to 800 lm depth,with their magnitude increasing with a reduced stepover distance.Application of hammer peening over 4% of the surface of the representative workpiece reduced the machininginduced distortions by 37%,and a coverage area of 100% led to and overcorrection by a factor of five.This confirms that hammer peening can be strategically applied(in target areas and changing the percentage of coverage)to correct low or severe distortions.展开更多
In past decades,high-entropy(HE)materials,containing five or more elements with approximately equal atomic ratio,are extensively investigated due to their desirable properties in a series of applications.Recently,HE t...In past decades,high-entropy(HE)materials,containing five or more elements with approximately equal atomic ratio,are extensively investigated due to their desirable properties in a series of applications.Recently,HE two-dimensional(2D)materials have become promising materials,which not only endow the advantages from their bulk form but also exhibit unusual properties due to their 2D features.So far,the HE 2D transition metal carbides(MXenes),dichalcogenides(TMDs),hydrotalcites(LDHs),and oxides have been successfully synthesized and performed well in different electrochemical reactions,which is originated from the synergistic effect of multicomponents and atomic thin characteristics.Here,the challenges on processing,characterization,and property predictions of HE 2D materials are emphasized.Finally,viable strategies,advanced processing,fundamental understanding,in-depth characterization of new HE 2D materials are proposed.展开更多
基金the financial support given from Elkartek Program to the project FRONTIERS 2022-Superficies multifuncionales en la frontera del conocimiento(KK-2022/00109)LOFAMO grant given by EPSRC(EP/X023281/1).
文摘Thin-walled aerostructural components frequently get distorted after the machining process.Reworking to correct distortions or eventually rejecting parts significantly increases the cost.This paper proposes a new approach to correct distortions in thin-walled components by strategically applying hammer peening on target surfaces of a machined component.Aluminium alloy 7475-T7351 was chosen for this research.The study was divided in two stages.First,the residual stresses(RS)induced by four different pneumatic hammer peening conditions(modifying the stepover distance and initial offset)were characterised in a test coupon,and one of the conditions was selected for the next stage.In the second stage,a FEM model was used to predict distortions caused by machining in a representative workpiece.Then,the RS induced by hammer peening were included in an FEM model to define two hammer peening strategies(varying the coverage area)to analyse the capability to reduce distortions.Two workpieces were machined and then treated with the simulated hammer peening strategies for experimental validation.Results in the test coupon showed that pneumatic hammer peening can generate high compressive RS(-50 to350 MPa)up to 800 lm depth,with their magnitude increasing with a reduced stepover distance.Application of hammer peening over 4% of the surface of the representative workpiece reduced the machininginduced distortions by 37%,and a coverage area of 100% led to and overcorrection by a factor of five.This confirms that hammer peening can be strategically applied(in target areas and changing the percentage of coverage)to correct low or severe distortions.
基金National Natural Science Foundation of China,Grant/Award Numbers:52125207,52072014,52102203Beijing Natural Science Foundation,Grant/Award Number:JQ20011+1 种基金China Postdoctoral Science Foundation,Grant/Award Numbers:2021M700008,2021M700316,2020TQ0022National Postdoctoral Program for Innovative Talents,Grant/Award Numbers:BX20200027,BX20200037。
文摘In past decades,high-entropy(HE)materials,containing five or more elements with approximately equal atomic ratio,are extensively investigated due to their desirable properties in a series of applications.Recently,HE two-dimensional(2D)materials have become promising materials,which not only endow the advantages from their bulk form but also exhibit unusual properties due to their 2D features.So far,the HE 2D transition metal carbides(MXenes),dichalcogenides(TMDs),hydrotalcites(LDHs),and oxides have been successfully synthesized and performed well in different electrochemical reactions,which is originated from the synergistic effect of multicomponents and atomic thin characteristics.Here,the challenges on processing,characterization,and property predictions of HE 2D materials are emphasized.Finally,viable strategies,advanced processing,fundamental understanding,in-depth characterization of new HE 2D materials are proposed.
