Transactions of Nanjing University of Aeronautics & Astronautics
Issue 3,2022 Table of Contents
2022(3):263-270.
DOI: 10.16356/j.1005-1120.2022.03.001
Abstract:
Gear skiving is a promising gear cutting technology that can achieve a multiple faster internal gear cutting process than that of gear shaping. However， the kinematic system complicates skiving process， resulting in severe crater wear due to the intense variation of local cutting features. In particular，the negative rake angle near the cut-out is recognized as influential factor affecting the cutter wear progress， which needs the sophisticated simulation approach to elucidate the underlying cutting mechanism. In this research， the influence of the rake angle， e.g. top and side nominal rake angles of the cutter， is studied to further understand its role in the gear skiving process， for seeking the possibility of skiving process improvement by calculating the effective rake angle. As a result， the top and side rake angles of the cutter can both increase the effective rake angle when compared with the case of the none-rake angle， leading to an enhanced skiving process. This work provides fundamental knowledge of the rake angle for the gear skiving research， contributing to the optimization on the cutter parameters by considering the effective rake angle.
Gear skiving is a promising gear cutting technology that can achieve a multiple faster internal gear cutting process than that of gear shaping. However， the kinematic system complicates skiving process， resulting in severe crater wear due to the intense variation of local cutting features. In particular，the negative rake angle near the cut-out is recognized as influential factor affecting the cutter wear progress， which needs the sophisticated simulation approach to elucidate the underlying cutting mechanism. In this research， the influence of the rake angle， e.g. top and side nominal rake angles of the cutter， is studied to further understand its role in the gear skiving process， for seeking the possibility of skiving process improvement by calculating the effective rake angle. As a result， the top and side rake angles of the cutter can both increase the effective rake angle when compared with the case of the none-rake angle， leading to an enhanced skiving process. This work provides fundamental knowledge of the rake angle for the gear skiving research， contributing to the optimization on the cutter parameters by considering the effective rake angle.
2022(3):271-279.
DOI: 10.16356/j.1005-1120.2022.03.002
Abstract:
The ideally straight hydraulic pipe is inexistent in reality. The initial curve caused by the manufacturing or the creep deformation during the service life will change the dynamic character of the system. The current work discusses the effect of the initial curve on the hydraulic pipe fixed at two ends for the first time. Based on the governing equation obtained via the generalized Hamilton’s principle， the potential energy changing with the height of the initial curve is discussed. The initial curve makes the potential energy curve asymmetric， but the system is always monostable. The initial curve also has very important influence on natural frequencies. It hardens the stiffness of the first natural mode at first and then has no effect on this mode after a critical value. On the contrast， the second natural frequency is constant before the critical value but increases while the height of the initial curve exceeds the critical value. On account of the initial value， the quadratic nonlinearity appears in the system. Forced resonance is very different from that of the ideally straight pipe under the same condition. Although the 2∶1 internal resonance is established by adjusting the height of the initial curve and the fluid speed， the typical double-jumping phenomenon does not occur under the initial curve given in the current work. This is very different from the straight pipe in the supercritical region. The work here claims that the initial curve of the hydraulic pipe should be taken into consideration. Besides， more arduous work is needed to reveal the dynamic characters of it.
The ideally straight hydraulic pipe is inexistent in reality. The initial curve caused by the manufacturing or the creep deformation during the service life will change the dynamic character of the system. The current work discusses the effect of the initial curve on the hydraulic pipe fixed at two ends for the first time. Based on the governing equation obtained via the generalized Hamilton’s principle， the potential energy changing with the height of the initial curve is discussed. The initial curve makes the potential energy curve asymmetric， but the system is always monostable. The initial curve also has very important influence on natural frequencies. It hardens the stiffness of the first natural mode at first and then has no effect on this mode after a critical value. On the contrast， the second natural frequency is constant before the critical value but increases while the height of the initial curve exceeds the critical value. On account of the initial value， the quadratic nonlinearity appears in the system. Forced resonance is very different from that of the ideally straight pipe under the same condition. Although the 2∶1 internal resonance is established by adjusting the height of the initial curve and the fluid speed， the typical double-jumping phenomenon does not occur under the initial curve given in the current work. This is very different from the straight pipe in the supercritical region. The work here claims that the initial curve of the hydraulic pipe should be taken into consideration. Besides， more arduous work is needed to reveal the dynamic characters of it.
2022(3):280-290.
DOI: 10.16356/j.1005-1120.2022.03.003
Abstract:
Based on the bulk free energy density and the degenerate mobility constructed by the quartic double-well potential function， a phase field model is established to simulate the evolution of intragranular microvoids due to surface diffusion in a stress field. The corresponding phase field governing equations are derived. The evolution of elliptical microvoids with different stressesΛ ![]()
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Λ ≥ Λ c ![]()
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β ≥ β c ![]()
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h ˉ ≤ h ˉ c ![]()
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Λ < Λ c ![]()
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β < β c ![]()
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h ˉ > h ˉ c ![]()
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Based on the bulk free energy density and the degenerate mobility constructed by the quartic double-well potential function， a phase field model is established to simulate the evolution of intragranular microvoids due to surface diffusion in a stress field. The corresponding phase field governing equations are derived. The evolution of elliptical microvoids with different stresses
2022(3):291-303.
DOI: 10.16356/j.1005-1120.2022.03.004
Abstract:
The frequent occurrence of control surface vibration has become one of the key problems affecting aircraft safety. The source of the freeplay of the control surface is studied， and a measurement device is developed. A nonlinear flutter analysis method under trimmed flight condition is proposed based on the discrete state-space method. Consequently， the effects of center-type freeplay and the freeplay with preload on flutter characteristics are analyzed， and the effects of preload on nonlinear flutter are verified by wind tunnel tests of a single wing model.
The frequent occurrence of control surface vibration has become one of the key problems affecting aircraft safety. The source of the freeplay of the control surface is studied， and a measurement device is developed. A nonlinear flutter analysis method under trimmed flight condition is proposed based on the discrete state-space method. Consequently， the effects of center-type freeplay and the freeplay with preload on flutter characteristics are analyzed， and the effects of preload on nonlinear flutter are verified by wind tunnel tests of a single wing model.
5 Design, Analysis, Fabrication, and Test for Low-Cost and Out-of-Autoclave Composite Airship Gondolas
2022(3):304-313.
DOI: 10.16356/j.1005-1120.2022.03.005
Abstract:
Out-of-autoclave（OoA） processing has the advantages of low cost， light weight and environmental protection， and has become a hot spot in the field of composite materials worldwide. This paper investigates the application of OoA processing in the gondola of the AS700 civil manned airship. The production cost of gondolas is reduced by selecting low cost materials such as glass fiber， PVC foam and OoA processing. The porosity of parts is reduced and controlled at about 2% by optimizing the edge breathing of prepreg during curing. The maximum tensile strain of the glass fiber is 4 593 μ ε ![]()
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μ ε ![]()
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Out-of-autoclave（OoA） processing has the advantages of low cost， light weight and environmental protection， and has become a hot spot in the field of composite materials worldwide. This paper investigates the application of OoA processing in the gondola of the AS700 civil manned airship. The production cost of gondolas is reduced by selecting low cost materials such as glass fiber， PVC foam and OoA processing. The porosity of parts is reduced and controlled at about 2% by optimizing the edge breathing of prepreg during curing. The maximum tensile strain of the glass fiber is 4 593
2022(3):314-325.
DOI: 10.16356/j.1005-1120.2022.03.006
Abstract:
Carbon-fiber reinforced polymer composites have been widely used to achieve the light-weighted design and high performance due to superior performance. Internal defects in the composite materials are the main factors that determine their performance， which makes reliable and effective detection methods of internal defects essential. Non-destructive testing （NDT） methods are the most widely-used way due to their tremendous advantages. Though the theoretical background is found， experimental results could be quite complicated and confusing， especially for composite materials with complex defects characteristics. In this paper， experimental study on internal defects in composite materials based on the time of flight （ToF） are investigated. The Gaussian echo model and the parameter estimation methods are established to build a theoretical model for measurements. Then， the distance amplitude correction （DAC） method is proposed to effectively improve the signal-to-noise ratio （SNR） and to reduce distortion of the signal during measurements. Finally， the ToF is adopted to determine depth of internal defects. Experiment study is conducted to investigate the porosity defects and the anti-impact performance of composite materials， as well as defects in objects with various thicknesses. Experimental results show that the proposed method is quite helpful for obtaining the intuition and deep understanding of internal defects， thus contributing to the determination of product performance and its improvement.
Carbon-fiber reinforced polymer composites have been widely used to achieve the light-weighted design and high performance due to superior performance. Internal defects in the composite materials are the main factors that determine their performance， which makes reliable and effective detection methods of internal defects essential. Non-destructive testing （NDT） methods are the most widely-used way due to their tremendous advantages. Though the theoretical background is found， experimental results could be quite complicated and confusing， especially for composite materials with complex defects characteristics. In this paper， experimental study on internal defects in composite materials based on the time of flight （ToF） are investigated. The Gaussian echo model and the parameter estimation methods are established to build a theoretical model for measurements. Then， the distance amplitude correction （DAC） method is proposed to effectively improve the signal-to-noise ratio （SNR） and to reduce distortion of the signal during measurements. Finally， the ToF is adopted to determine depth of internal defects. Experiment study is conducted to investigate the porosity defects and the anti-impact performance of composite materials， as well as defects in objects with various thicknesses. Experimental results show that the proposed method is quite helpful for obtaining the intuition and deep understanding of internal defects， thus contributing to the determination of product performance and its improvement.
2022(3):326-337.
DOI: 10.16356/j.1005-1120.2022.03.007
Abstract:
Intelligent structures like zero Poisson’s ratio （ZPR） cellular structures have been widely applied to the engineering fields such as morphing wings in recent decades， owing to their outstanding characteristics including light weight and low effective modulus. In-plane and out-of-plane mechanical properties of ZPR cellular structures are investigated in this paper. A theoretical method for calculating in-plane tensile modulus， in-plane shear modulus and out-of-plane bending modulus of ZPR cellular structures is proposed， and the impacts of the unit cell geometrical configurations on in-plane tensile modulus， in-plane shear modulus and out-of-plane bending modulus are studied systematically based on finite element （FE） simulation. Experimental tests validate the feasibility and effectiveness of the theoretical and FE analysis. And the results show that the in-plane and out-of-plane mechanical properties of ZPR cellular structures can be manipulated by designing cell geometrical parameters.
Intelligent structures like zero Poisson’s ratio （ZPR） cellular structures have been widely applied to the engineering fields such as morphing wings in recent decades， owing to their outstanding characteristics including light weight and low effective modulus. In-plane and out-of-plane mechanical properties of ZPR cellular structures are investigated in this paper. A theoretical method for calculating in-plane tensile modulus， in-plane shear modulus and out-of-plane bending modulus of ZPR cellular structures is proposed， and the impacts of the unit cell geometrical configurations on in-plane tensile modulus， in-plane shear modulus and out-of-plane bending modulus are studied systematically based on finite element （FE） simulation. Experimental tests validate the feasibility and effectiveness of the theoretical and FE analysis. And the results show that the in-plane and out-of-plane mechanical properties of ZPR cellular structures can be manipulated by designing cell geometrical parameters.
2022(3):338-348.
DOI: 10.16356/j.1005-1120.2022.03.008
Abstract:
Cloud manufacturing has become a reality. It requires sensing and capturing heterogeneous manufacturing resources and extensive data analysis through the industrial internet. However， the cloud computing and service-oriented architecture are slightly inadequate in dynamic manufacturing resource management. This paper integrates the technology of edge computing and microservice and develops an intelligent edge gateway for internet of thing （IoT）-based manufacturing. Distributed manufacturing resources can be accessed through the edge gateway， and cloud-edge collaboration can be realized. The intelligent edge gateway provides a solution for complex resource ubiquitous perception in current manufacturing scenarios. Finally， a prototype system is developed to verify the effectiveness of the intelligent edge gateway.
Cloud manufacturing has become a reality. It requires sensing and capturing heterogeneous manufacturing resources and extensive data analysis through the industrial internet. However， the cloud computing and service-oriented architecture are slightly inadequate in dynamic manufacturing resource management. This paper integrates the technology of edge computing and microservice and develops an intelligent edge gateway for internet of thing （IoT）-based manufacturing. Distributed manufacturing resources can be accessed through the edge gateway， and cloud-edge collaboration can be realized. The intelligent edge gateway provides a solution for complex resource ubiquitous perception in current manufacturing scenarios. Finally， a prototype system is developed to verify the effectiveness of the intelligent edge gateway.
2022(3):349-357.
DOI: 10.16356/j.1005-1120.2022.03.009
Abstract:
As a result of the recently increasing demands on high-performance aero-engine， the machining accuracy of blade profile is becoming more stringent. However， in the current profile， precision milling， grinding or near-net-shape technology has to undergo a tedious iterative error compensation. Thus， if the profile error area and boundary can be determined automatically and quickly， it will help to improve the efficiency of subsequent re-machining correction process. To this end， an error boundary intersection approach is presented aiming at the error area determination of complex profile， including the phaseⅠof cross sectional non-rigid registration based on the minimum error area and the phaseⅡof boundary identification based on triangular meshes intersection. Some practical cases are given to demonstrate the effectiveness and superiority of the proposed approach.
As a result of the recently increasing demands on high-performance aero-engine， the machining accuracy of blade profile is becoming more stringent. However， in the current profile， precision milling， grinding or near-net-shape technology has to undergo a tedious iterative error compensation. Thus， if the profile error area and boundary can be determined automatically and quickly， it will help to improve the efficiency of subsequent re-machining correction process. To this end， an error boundary intersection approach is presented aiming at the error area determination of complex profile， including the phaseⅠof cross sectional non-rigid registration based on the minimum error area and the phaseⅡof boundary identification based on triangular meshes intersection. Some practical cases are given to demonstrate the effectiveness and superiority of the proposed approach.
2022(3):358-366.
DOI: 10.16356/j.1005-1120.2022.03.010
Abstract:
The Al-Cu-Li alloy is welded by using laser beam welding， and the welding wire ER4043 is used as filler metal. The microstructure and mechanical property of welded joints are systematically investigated. Microstructure analyses show that the fusion zone is mainly composed of α-Al matrix phase and some strengthening phases including T， δ′， θ′， β′ and T1， etc. During welding， the weld formation and joint quality are obviously improved by the addition of Al-Si filler wire. The measurements of mechanical property indicate that， compared with that of the base metal （BM）， the microhardness in the weld zone is decreased to a certain extent. Under the appropriate welding parameters， the tensile strength of welded joint reaches 369.4 MPa， which is 67.8% of that of the BM. There are many dimples on the joint fracture surface， and it mainly presents the fracture characteristic of dimple aggregation.
The Al-Cu-Li alloy is welded by using laser beam welding， and the welding wire ER4043 is used as filler metal. The microstructure and mechanical property of welded joints are systematically investigated. Microstructure analyses show that the fusion zone is mainly composed of α-Al matrix phase and some strengthening phases including T， δ′， θ′， β′ and T1， etc. During welding， the weld formation and joint quality are obviously improved by the addition of Al-Si filler wire. The measurements of mechanical property indicate that， compared with that of the base metal （BM）， the microhardness in the weld zone is decreased to a certain extent. Under the appropriate welding parameters， the tensile strength of welded joint reaches 369.4 MPa， which is 67.8% of that of the BM. There are many dimples on the joint fracture surface， and it mainly presents the fracture characteristic of dimple aggregation.
2022(3):367-378.
DOI: 10.16356/j.1005-1120.2022.03.011
Abstract:
The visual inspection is an economical and effective method for welding. For measuring the feature sizes of grooves， a method based on line structured light is presented. Firstly， an adaptive algorithm to extract the sub-pixel centerline of structured light stripes is introduced to deal with the uneven width and grayscale distributions of laser stripes， which is based on the quadratic weighted grayscale centroid. By means of region-of-interest （ROI） division and image difference， an image preprocessing algorithm is developed for filtering noise and improving image quality. Furthermore， to acquire geometrical dimensions of various grooves and groove types precisely， the sub-pixel feature point extraction algorithm of grooves is designed. Finally， experimental results of feature size measuring show that the absolute error of measurement is 0.031—0.176 mm， and the relative error of measurement is 0.2%—3.6%.
The visual inspection is an economical and effective method for welding. For measuring the feature sizes of grooves， a method based on line structured light is presented. Firstly， an adaptive algorithm to extract the sub-pixel centerline of structured light stripes is introduced to deal with the uneven width and grayscale distributions of laser stripes， which is based on the quadratic weighted grayscale centroid. By means of region-of-interest （ROI） division and image difference， an image preprocessing algorithm is developed for filtering noise and improving image quality. Furthermore， to acquire geometrical dimensions of various grooves and groove types precisely， the sub-pixel feature point extraction algorithm of grooves is designed. Finally， experimental results of feature size measuring show that the absolute error of measurement is 0.031—0.176 mm， and the relative error of measurement is 0.2%—3.6%.
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