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2020 Vol. 63, No. 19
Published: 2020-10-01
FEATURE
FORUM
RESEARCH
C0NTENTS
COVER STORY
APPROACHING SCIENCE
 
       FEATURE
14 Non-Destructive Testing for Aerospace Composite Structures Using Laser Ultrasonic Technique
QIU Jinhao, ZHANG Chao, JI Hongli, TAO Chongcong
DOI: 10.16080/j.issn1671-833x.2020.19.014
Aimed at solving the problem of large-area detection for aerospace laminated structures with curved surfaces, laser ultrasonic technique with non-contact measurement has attracted more and more attention. By using pulsed laser to generate the ultrasonic waves in the structures, the wave-field data can be obtained. Through analyzing the characteristics of ultrasonic wave propagation, the structural damage detection and mechanical property identification can be achieved. Focused on the widely used aerospace composite structures, this paper presents the research progress on three aspects: debonding damage detection, damage accumulation characterization and fatigue life prediction. Taking laminated composite structures as an example, the influence of debonding damage on ultrasonic wave propagation is studied. By extracting the damage index, such as wave energy and wave number, the debonding damage can be visualized. Then, the influence of matrix crack accumulation in fiber reinforced polymer on mode conversion is investigated. By defining a mode-to-mode ratio, the density of matrix cracks can be characterized. Finally, a micro-damage based fatigue evolvement model for composites is established. Through Bayesian model averaging and wave velocity measurement using laser ultrasonic technique, the fatigue life of composites can be predicted, providing foundation for non-destructive testing in aerospace composite structures.
2020 Vol. 63 (19): 14-23 [Abstract] ( 298 ) HTMLNew PDF (18133 KB)  ( 213 )
       COVER STORY
24 Progress in Non-Destructive Testing and Evaluation of SiCf /SiC Composites
LIU Songping, LIU Feifei, ZHANG Qingle, LI Zhiying
DOI: 10.16080/j.issn1671-833x.2020.19.024
As silicon carbide fibre/silicon carbide ceramicmatrix composites (SiCf/SiC CMCs) have become widely used in high temperature hot-section components in aerospace and aero-engines, nondestructive testing and evaluation (NDT & E) is particularly important. Due to the special high temperature manufacturing process, internal microstructure and defect characteristics of SiCf/SiC CMCs, it is difficult to realize reliable NDT & E of SiCf/SiC CMCs by using existing detection techniques and defect evaluation methods. Based on the studies in this field in the recent years, the defects and characteristics of SiCf/SiC CMCs are analyzed. The research progress in NDT&E of SiCf/SiC CMCs is reviewed. The main technical challenges in NDT&E of SiCf/SiC CMCs are presented. The future development tendency in NDT & E of SiCf/SiC CMCs is given. At present, high-resolution digital X–ray imaging and high-resolution asymmetric-frequency ultrasonic detection techniques have become very important methods for the NDT & E of SiCf/SiC CMCs, and good practical testing and applications have been obtained.
2020 Vol. 63 (19): 24-30 [Abstract] ( 280 ) HTMLNew PDF (4371 KB)  ( 707 )
       FORUM
34 Experimental Study on Fatigue Monitoring of Titanium Alloy Based on Weak Magnetic Technology
ZHANG Bin, YU Runqiao,HU Bo
DOI: 10.16080/j.issn1671-833x.2020.19.034
Titanium alloy is subject to cyclic load for a long time in service, and the components are prone to fatigue fracture. Fatigue monitoring of titanium alloy structure is of great significance to industrial safety. In this paper, a fatigue monitoring method combined with weak magnetic field measurement is proposed. On the basis of weak magnetic testing technology, the force magnetic model of weak magnetic monitoring is put forward, the standard tensile test block is made, the weak magnetic monitoring system and fatigue test system are used for fatigue monitoring test, and the lattice constants before and after fatigue were measured. The results show that the change of magnetic signal in fatigue test has good coincidence and consistency with the fatigue process, and the magnetic signal in the most extended stage of fatigue life keeps stable and small amplitude fluctuation, and finally the magnetic signal rises sharply in the transient area. In the last stage of fatigue, the sample in the stage of instantaneous fracture is fractured, and the monitoring magnetic curve is greatly enhanced. The curve results are consistent with the force and magnetic model, the cross-section of the magnetic line of force in the vertical direction increases, and the magnetic signal is enhanced when the cell is compressed. It has been proven that it is feasible to monitor the fatigue of titanium alloy with weak magnetic field.
2020 Vol. 63 (19): 34-40/55 [Abstract] ( 204 ) HTMLNew PDF (12683 KB)  ( 380 )
41 Research on Inspection Technology of Aviation Tube Based on Laser Scanning
WANG Wei, JIN Wenhan
DOI: 10.16080/j.issn1671-833x.2020.19.041
The manufacturing accuracy of aviation tube is one of the important factors that affect the assembly quality, it is necessary to inspect the manufacturing accuracy of tube before assembly. At present, the commonly used inspection method is to verify by mechanical checking-tools, but there are some defects such as low precision and low efficiency. So an efficient and accurate digital inspection technology of tube is proposed, in order to ensure the accuracy of inspection results and improve the production efficiency of tube. Non-contact measurement method is used to obtain the surface point cloud data of tube based on laser scanning technology, in the inspection system, the central axis, bending points and bending elements of point cloud data are extracted to make error analysis compared with the theoretical model of tube, and then the bending coefficient can be corrected, and high quality tubes will be produced by sending the correction data to the bending machine.
2020 Vol. 63 (19): 41-46/72 [Abstract] ( 187 ) HTMLNew PDF (4904 KB)  ( 377 )
47 Online Monitoring for Porosity Prediction in Directed Energy Deposition Processes
ZHANG Min, WANG Xingcheng, CHAN Yufei, CHEN Changjun
DOI: 10.16080/j.issn1671-833x.2020.19.047
With the rapid development of manufacturing industry, additive manufacturing (AM) technology has attracted more and more attention in the world. Additive manufacturing has been rapidly developed and widely used in aerospace, industrial machinery, automobile electronics and other fields. The biggest theoretical challenge of direct energy deposition (DED) technology at present is the lack of a deep understanding of the inherent relationship between the process-microstructure-performance, and the lack of an effective and cost-effective online monitoring process in the actual production process. Therefore, the repeatability, uniformity and reliability of the products manufactured by DED are difficult to meet the increasing production requirements of industry. This article introduces the DED in the process of heatphysical mechanism of the process. On the basis of summarizing the changes in temperature, molten pool size and molten pool morphology during the manufacturing process, summarizes the research of AM based on DED of online monitoring in the stomatal monitoring, and points out the existing problems and future development direction.
2020 Vol. 63 (19): 47-55 [Abstract] ( 239 ) HTMLNew PDF (28262 KB)  ( 104 )
56 Research on Visual Alignment Technology of Industrial Robotic Arm in Multi-Station Operation
ZHU Hongyu,ZENG Lingbin,SHI Shifeng,YE Nan
DOI: 10.16080/j.issn1671-833x.2020.19.056
A monocular-vision-based alignment technique is proposed to achieve accurate alignment of tool end in multi-station operation with an industrial robotic arm. To begin with, the system calibration is carried out to establish coordinates mapping between the concerning coordinate systems. After that, a set of cooperative targets is designed and arranged near the alignment objects on the workpiece. The expected poses of cooperative targets can be obtained by offline measurement and a task table for alignment targets is then built up. In the multi-station operation stage, driven by the task table, the current poses of the targetsare calculated by the vision system, and the deviations between the current poses and expected poses are calculated. Then parameters to move the robot arm are evaluated according to the deviations by the coordinates mapping. By iterating the above steps, the final alignment is worked out upon the designed threshold. The experimental results show that the alignment accuracy can reach 0.1mm in X and Y direction, 0.2mm in Z direction, and the angle error is better than 0.1° in the measuring distance of 260mm.
2020 Vol. 63 (19): 56-65 [Abstract] ( 165 ) HTMLNew PDF (7430 KB)  ( 102 )
66 Research on Surface Roughness Detection Index of Micro-Milling Based on Multi-Objective Optimization
LI Wenqin, XU Jinkai, YU Huadong, ZHANG Xianghui, LIU Qimeng, YU Zhanjiang
DOI: 10.16080/j.issn1671-833x.2020.19.066
Since the fact that the surface topography of micro-milling is complex and difficult to evaluate accurately, a surface roughnessdetection index based on three-dimensional (3D) characterization is proposed. Firstly, on the basis of principal component analysis, the 3D surface roughness parameters Sa, Ssk and Sku are converted into gray correlation degree as a surface roughness detection index based on the gray correlation analysis method. Secondly, the response surface methodology (RSM) is used to establish a gray correlation degree model to analyze the influence of machining parameters on the GRG. Finally, the combination of optimal machining parameters is obtained and verified. The results show that the average relative error of the gray correlation degree model is 6.54%, the fitting accuracy is high and the prediction effect is good, which verifies the feasibility of the model. The GRG corresponding to the obtained optimal process parameter combination is increased by 15.27%, which realizes the purpose of surface roughness minimization and surface abnormal features minimization and proves the feasibility of the detection index.
2020 Vol. 63 (19): 66-72 [Abstract] ( 196 ) HTMLNew PDF (4789 KB)  ( 238 )
       APPROACHING SCIENCE
74 Promoting Non-Destructive Testing Technology Intelligentization
2020 Vol. 63 (19): 74-75 [Abstract] ( 141 ) HTMLNew PDF (614 KB)  ( 260 )
       RESEARCH
76 Numerical Simulation Analysis of Ultrasonic Vibration Riveting of TA1 Countersunk Head Rivets
ZHAI Yadi,WANG Zhiliang,FU Fangyan,ZHAN Jianghu,TONG Xinbo,LIN Jun
DOI: 10.16080/j.issn1671-833x.2020.19.076
With the development of aerospace, high-speed trains, bridges and other industries in China, a large number of light-weight and high-strength metal alloy or composite materials will be widely used, which requires the use of large-diameter and high-strength rivets for plate riveting to achieve effective assembly and connection of large-scale structural parts. However, the traditional riveting technology has some quality problems, such as the difficulty of forming rivets, the easy cracking of upsets, and the difficulty of controlling interference fit. Introducing the ultrasonic vibrationassisted plastic processing technology into the traditional press riveting process, which helps reduce the metal deformation resistance and improves the forming performance, is expected to improve the above problems. In this paper, ABAQUS finite element analysis software is used to simulate the process of TA1 countersunk rivet traditional press riveting and ultrasonic vibration-assisted riveting of double-layer C45 plate, analyze the deformation process of plate and rivet, and compare the factors that affect the riveting quality of the joint, such as riveting force, shear stress, residual stress and interference. The results show that ultrasonic vibration-assisted riveting can significantly reduce the riveting pressure, the shear stress and residual stress of the rivet, so that the riveting piece can obtain a uniform and reasonable amount of interference, thereby effectively improving the riveting quality
2020 Vol. 63 (19): 76-84/90 [Abstract] ( 217 ) HTMLNew PDF (9458 KB)  ( 220 )
85 Effect of Heat Treatment on Microstructure and Tensile Properties of EBM Ti–4Al–5V–5Mo–6Cr–1Nb Alloy
QIAO Hong,LIU Yunxi,CHEN Wei, YANG Yang
DOI: 10.16080/j.issn1671-833x.2020.19.085
The effect of heat treatment on microstructure and tensile properties of EBM Ti–45561 was investigated. The as-build material exhibited columnar β grains epitaxially grew along z direction, which is caused by the temperature gradient during the solidification process. Acicular α phase precipitated inside each β grains due to the 730℃ environment temperature. With the increase of post-build annealing temperature and extension of annealing time, the grain boundary α phase and secondary α phase were both coarsened. When the solution treat temperature was increased, the percentage of primary α phase decreased. Among the 3 heat treatment parameters, the annealing temperature has the strongest influence on tensile properties, and the annealing time has the smallest influence. The elongation of the EBM Ti–45561 increased with annealing temperature; while the strength of the material decreased with annealing temperature.
2020 Vol. 63 (19): 85-90 [Abstract] ( 215 ) HTMLNew PDF (4300 KB)  ( 219 )
91 Heat Transfer Performance of Carbon Fiber Reinforced Resin Matrix Laminated Composites
QIU Xueqiong, JIN Yi,CHEN Lin
DOI: 10.16080/j.issn1671-833x.2020.19.091
With the increase of applications of composites in airplane structures, the thermally-induced stresses are critical issues in composite-metal hybrid structures. In order to analyze thermally-induced structural stresses, accurate structural temperature field value is necessary, while the heat transfer performance of the materials is of great importance for the structural temperature field analysis. Due to the anisotropy of heat transfer performance of composites, which is dependent on the layer and structure of laminates, it results in difficulties in evaluation of thermal conductivities. Based on the ASTM E1461, the samples with different structures were designed, and the thermal conductivities in depth direction and in-plane direction of the T800 carbon fiber reinforced resin laminates were tested through flash method. The thermal conductivities for laminates in different stack types were studied. And also, the thermal stack theory of thermal conductivity for composite laminates in in-plane direction was verified. This work provided a fast approach for evaluation of thermal conductivity of carbon fiber reinforced resin matrix laminated composites.
2020 Vol. 63 (19): 91-95/102 [Abstract] ( 224 ) HTMLNew PDF (2304 KB)  ( 379 )
96 Analysis-Suitable T-Spline Fitting for Sculptured Surface Reconstruction
LU Yu,WANG Jian,PENG Lihua,XU Long
DOI: 10.16080/j.issn1671-833x.2020.19.096
Surface reconstruction with high efficiency and accuracy is required in advanced aerospace manufacturing and measurement. As wildly used models, B-spline and NURBS are the main tools for surface reconstruction in existing methods. However, the topological constrains of B-splines and NURBS control meshes make it produce a lot of redundant control points when modeling surfaces. Newly proposed T-splines in recent years have provided a method to solve this problem. Analysis-suitable T-splines (ASTS), a subset of T-splines with certain topological constrains were later developed, which optimized the mathematical properties and localized refinement capability of T-splines. T-splines have been successfully applied to surface reconstruction, while ASTS-based surface reconstruction algorithms are in vacancy at the moment. This paper proposes a surface reconstruction method based on analysis-suitable T-splines. Adaptive construction of an initial AST-mesh and efficient local refinement are performed in the algorithm to generate an ASTS surface within certain tolerance. Our experimental results show that the proposed ASTS fitting can generate spline surface with higher accuracy than NURBS fitting with the same amount of control parameters. The computing efficiency of the proposed algorithm is higher than simple T-spline fitting.
2020 Vol. 63 (19): 96-102 [Abstract] ( 205 ) HTMLNew PDF (5289 KB)  ( 404 )
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