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2019 Vol. 39, No. 10

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2019, 39(10): .
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2019, 39(10): .
Abstract(647) PDF(315)
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Local Damage Characteristics of Ship Structure by Near Field Explosion Load
LI Ying, LIN Xin, WANG Shi-ping, LI Song-jie
2019, 39(10): 991-998. doi:10.15918/j.tbit1001-0645.2019.10.001
Abstract(1208) PDF(483)
Abstract:
In this paper, the arbitrary Lagrangian-Eulerian (ALE) method was used to study the damage characteristics of the cabin structure under underwater near-field explosion and underwater contact explosion. The method was firstly used to simulate the peak value of the shock wave generated by the TNT explosive in underwater explosion, and the simulated value obtained by the simulation was compared with the calculated value of the empirical formula to verify the effectiveness of the method. Then the method was used to verify the underwater contact explosion experiment of the plate, and the simulation results were compared with the experimental results to further verify the effectiveness of the ALE method. Finally, the ALE method was used to simulate the submarine near-field explosion and underwater contact explosion of different structural types. The damage characteristics of different structural types of subdivisions under different working conditions were studied.
Experimental Study on PLC Effect and Acoustic Emission Characteristics of Aluminum Alloy
REN Hui-lan, AN Gang, HAO Li, WANG Zong-lian
2019, 39(10): 999-1005. doi:10.15918/j.tbit1001-0645.2019.10.002
Abstract(851) PDF(358)
Abstract:
Considering the influence of annealing temperature and strain rate on the mechanical properties of 6063 aluminum alloy, the PLC effect and acoustic emission characteristics of aluminum alloy were experimentally studied by material testing machine and acoustic emission testing system. The stress-strain curves of materials under different strain rates and the variation of acoustic emission parameters at different annealing temperatures were obtained. The results show that the stress-strain curves of 6063 aluminum alloy exhibit obvious PLC phenomenon when loaded at strain rates of 2×10-3, 2×10-4and 2×10-5s-1. When the strain rate is reduced, the PLC phenomenon is enhanced, and the conversion from type A to type C occurs. The critical strain of the PLC effect decreases with the increasing annealing temperature at 2×10-4s-1. With the increase of the dynamic dislocation density on the mesostructure, the acoustic emission ringing count increases sharply and reaches the peak value in the yield stage. The acoustic emission activity is weakened in the plastic hardening stage. The burst type signal is generated in the elastic stage and the plastic strengthening stage, while the continuous signal is generated in the yield stage, which is related to the uniform deformation of the specimen and the formation and propagation of the shear deformation zone.
Dynamic Flexural Mechanical Behavior of Annealed and Chemically Strengthened Silicate Glass
WANG Zhen, SUO Tao, LI Yu-long, WANG Xiang, WANG Yin-mao
2019, 39(10): 1006-1011. doi:10.15918/j.tbit1001-0645.2019.10.003
Abstract(1155) PDF(378)
Abstract:
By using an electronic universal testing machine and a modified split Hopkinson pressure bar device, three-point bending tests were conducted on annealed and chemically strengthened glass at the loading speed of 1.67×10-6m/s and 2.5 m/s. In dynamic tests, the force equilibrium between the incident and transmitted bar end was validated to prove the validity of dynamic results. A high-speed camera was also used to record the failure process of the specimens during the tests. The experiment results are as follows:the flexural strength of chemically strengthened glass is higher than that of annealed glass significantly, and the strength dispersion of chemically strengthened glass decreases, due to the existence of surface pro-compression stress. With the increase of loading speed, the flexural strength of glass specimens increases significantly and the strength dispersion decreases. Under dynamic loading conditions, multiple cracks form and propagate in the specimens.
Study on Ride Comfort of Active Suspension with 9 Degrees of Freedom
PAN Cheng-long, RONG Ji-li, XIANG Da-lin, ZHENG Yu-long
2019, 39(10): 1012-1017. doi:10.15918/j.tbit1001-0645.2019.10.004
Abstract(1221) PDF(397)
Abstract:
Based on the theory of vehicle system dynamics and Lagrange's theorem, the dynamics equation of the nine-degree freedom active suspension of the instrument-vehicle-road coupling was derived. White noise was used as the random road roughness excitation of the left and right wheels. LQR controller was designed according to the optimal control principle, and an active suspension control simulation model was established. An adaptive particle swarm algorithm was used to optimize the weighting coefficientQ, and the root mean square values of the equipment acceleration and other performance parameters of the active suspension were compared and analyzed with passive suspension. Simulation results show that the LQR controller, which is optimized by adaptive particle swarm optimization, can significantly improve the ride comfort and protect the reliability of on-board equipment.
Deformation and Fracture Analysis of PBX Arch Specimens Based on Plasticity Damage Theory
LI Shang-kun, HUANG Xi-cheng, WANG Peng-fei, HAO Zhi-ming, XU Wei-fang, LAN Lin-gang
2019, 39(10): 1018-1025. doi:10.15918/j.tbit1001-0645.2019.10.005
Abstract(892) PDF(338)
Abstract:
Plasticity damage theory was used to simulate the deformation and fracture process of PBX circular arch specimens subjected to compression. The bearing capacity and crack shape of specimens at constraint conditions were analyzed. The comparison between experiment and simulation shows that the bearing capacity of specimens rises with the increase of friction. Simulation results agree with the experiment data well when the friction coefficient equals to 0.2; the bearing capacity of specimens is greatly improved at restriction conditions, and the specimens can still bear loading when a crack appears; the specimens break twice at strong restriction when it comes to continued loading, and this process has been reproduced by simulation. The simulation have a good agreement with experimental results in terms of the shape of cracks and carrying capacity. So plasticity damage model can be used to analyze the deformation and fracture of PBX specimens.
Simulation Method for CFRP/AA6061 Thin-Walled Structure Subjected to Axial Crushing
YU Hai-yan, SHI Hui-ru, CHEN Si-ji
2019, 39(10): 1026-1033,1038. doi:10.15918/j.tbit1001-0645.2019.10.006
Abstract(923) PDF(360)
Abstract:
Firstly, using LSDYNA software, a CFRP/AA6061 composite tube model was established with CFRP wrapped around the outer wall of aluminum alloy tube to study suitable crushing simulation method. And then, the MAT54 and MAT123 material models were used respectively to simulate the constitutive relation of CFRP and AA6061. The normal failure stress and shear failure stress at the interface between CFRP and AA6061 were determined by calibrating parameters, and the interface was defined according to tiebreak contact type. Finally, taking the composite structure with different angle fiber layers as the object, a crush test was carried out to validate the simulation model. The results show that, the simulation model constructed in this paper presents high precision and can reflect well the peak crush force and mean crush force during the test. The simulation error of[0/90]3and[90]6layer composite tube can reach 8% and 11.2% respectively for peak crush force,8.7% and 6.7% respectively for mean crush force. This model can also simulate the axial crushing performance and failure mode of the composite structure. This model can be used for the crushing test and simulation study of CFRP/aluminum alloy composite thin-walled structures.
Coherence of Phase Angle of Harmonic Superposition Components in Time Domain Simulation of Road Roughness for Right and Left Wheel Tracks
WANG Han-ping, ZHANG Zhe, LI Qian
2019, 39(10): 1034-1038. doi:10.15918/j.tbit1001-0645.2019.10.007
Abstract(1707) PDF(293)
Abstract:
Based on road roughness profiles generated by harmonic superposition method, the auto-power spectral density and cross-power spectral density characteristics were reversed. According to the coherence function of the left and right wheel tracks, the analytic coherence relation of the phase angles of the corresponding harmonic superposition components in the road roughness profiles of the left and right wheel tracks generated by harmonic superposition method was derived. Taking the coherence of wheel tracks into account, a model of 3D road surface roughness was built. The simulation results of 3D road roughness profile based on Matlab showed that the auto-power spectral densities were almost identical, and the simulation coherence function of the left and right wheel tracks was in good agreement with the specified coherence function, which verifies the high reliability of the phase angle correlation of the harmonic superposition components in computer simulations. It also provides a more reliable simulation model for 3D road simulation.
Research on Dynamic Burst Location Method Based on Air Blast Shock Wave
LÜ Zhong-jie, HAN Jin-liang, LI Hao-yang, HUANG Feng-lei
2019, 39(10): 1039-1044. doi:10.15918/j.tbit1001-0645.2019.10.008
Abstract(871) PDF(363)
Abstract:
In order to solve the problem that the position of the airborne dynamic explosion is difficult to measure, a five-zone positioning method based on the results of the shock wave overpressure test was studied. The digital pressure recorder was composed of a test square in the explosion area, and all the measuring points were divided into five zones according to the estimated distance from the estimated point of the heart. Multiple sets of measuring points were obtained by selecting one measuring point in each zone, and the relative coordinates of each set of measuring points and the shock wave overpressure value were taken as raw data. The functional equations were established based on the airborne static explosion free-field shock wave propagation law, the dynamic explosion shock wave overpressure engineering calculation formula, and the wall reflection law. The Matlab software and the Levin-Marquard method were used to iteratively get a set of core coordinates, and the Gurbus method was used to eliminate the anomaly data and calculate the average of the remaining data to obtain the final three-dimensional coordinates of the core. Combined with the actual explosion test, the calculation results were compared with the monitoring results. The results show that the method is reliable and effective for obtaining core coordinates.
Research on Mechanical Environment Adaptability Technology of Airborne Dry Biochemical Analyzer
GUO Lei, XING Li-hua, YUAN Qian, GE Fang-jun
2019, 39(10): 1045-1050. doi:10.15918/j.tbit1001-0645.2019.10.009
Abstract(824) PDF(348)
Abstract:
Due to the low structural strength and poor vibration isolation, the ground dry biochemical analyzer will suffer from damage and functional failure in the airborne working environment. A design method was proposed for the strength improvement and vibration isolation of dry biochemical analyzer, and verified by finite element analysis and mechanical tests. The results show that the strength safety margin can be more than 1.5, the vibration isolation efficiencies can be up to 56%, the performance index meets the quality control standard, and meets the requirements of aeromechanics after improvement.
Structure Design and Performance Study of a Multi-Layer Thermal Protection Component with High Temperature Endurance
LI Jian, ZHANG Fan, ZHANG Li-juan, LI Wen-jing, ZHAO Ying-min
2019, 39(10): 1051-1056. doi:10.15918/j.tbit1001-0645.2019.10.010
Abstract(831) PDF(351)
Abstract:
The structure design method and thermal protection performance of a multi-layer thermal protection component composed of different functional layers were investigated. A simulation calculation was applied to simulate the thermo-responsive behavior of the component composed of ablator layer and insulation layer materials with different thicknesses. And a quartz lamp heating test was carried out to verify the thermostable performance, insulation ability and reusable property of the optimized component. The results show that, the compact ablator layer material possesses an excellent thermostable performance and the insulation layer material composed of aerogel has an ultra-low thermal conductivity. The multi-layer component, matching the designed thicknesses for the target environment, can go through an 1 600℃ heating test with a low back-side temperature of only 118℃.
Direct Model Predictive Rotating Speed Control for Rudder in Dual-Spin Projectile with Output-Feedback Extended State Observer
YIN Ting-ting, JIA Fang-xiu, YU Ji-yan, WANG Xiao-ming
2019, 39(10): 1057-1062,1068. doi:10.15918/j.tbit1001-0645.2019.10.011
Abstract(1192) PDF(340)
Abstract:
The rotating system of the fixed rudder canards in the dual-spin trajectory correction projectile is a typical nonlinear system with parametric uncertainties and uncertain nonlinearities. A direct model predictive control (DPC) based on the output-feedback extended state observer (ESO) was proposed for rotation speed control. The general disturbance was estimated and added to the controller design as feedforward compensation by ESO while DPC completed rotating speed prediction and control based on the compensated dynamic roll model. The time-varying nonlinear parameters were linearly processed in the extremely short state update time interval to decrease the computation amount, where the complex integral traversal operation was converted into a low-order equation solution problem. The simulation results reveal that the proposed method can accurately estimate the system states and disturbance, and hence it possesses the advantages of high accuracy, rapid response, strong robustness and adaptability.
Group Activity Recognition Based on Tensor Features and Twin Support Vector Machines
HU Gen-sheng, ZHANG Le-jun, ZHANG Yan
2019, 39(10): 1063-1068. doi:10.15918/j.tbit1001-0645.2019.10.012
Abstract(735) PDF(315)
Abstract:
To improve the accuracy of group activity recognition in video, a group activity recognition algorithm was proposed based on tensor feature and twin support vector machine. Firstly, the activity of group in each frame was described by combining the posture structure information in the joint skeleton of the group members and the social network information of the group. The tensor form was used to represent the features of group activity. Then, the tensor kernel was decomposed by using multi-channel nonlinear feature mapping and the model parameters of the tensor kernel twin support vector machine were optimized by using the particle swarm optimization method. Finally, the group activity recognition in video was realized by combining tensor features and twin support vector machine. Experiments performed on the CAD2 dataset and the self-built dataset show that the tensor feature can effectively represent the group activity. Compared with the existing approach, the proposed algorithm can effectively improve the accuracy of the group activity recognition.
Resonator Design of Wireless Power Transfer System with Broadband Magnetic Coupling Property
AN Hui-lin, LIU Guo-qiang, LI Yan-hong, SONG Jia-xiang, ZHANG Chao
2019, 39(10): 1069-1074,1080. doi:10.15918/j.tbit1001-0645.2019.10.013
Abstract(1017) PDF(341)
Abstract:
In order to improve the working frequency range of wireless power transfer system and quantificational design parameters of resonator, based on the theory of magnetic resonant coupling, the circuit model equation has been established. The relationship between the transmission characteristics and coil parameters has been studied. In the case of specifying resonant frequency, transmission distance, load and receiving power, the method of selecting the winding radius and turn number has been realized. At the same time, when the resonator parameters are given, the variation characteristics of transmission characteristics with transmission distance has been simulated. Finally, combined with the resonator design of broadband power converter for magnetic coupling resonance wireless energy transfer system, the theoretical deduction and simulation calculation have been validated by the experimental analysis, the results show that experimental result is consistent with theoretical analysis and simulation.
Optimal Trajectory Tracking Predictive Control of Every Motion Axis for Rehabilitative Training Walker Considering Human-Robot Interaction Forces
SUN Ping, SUN Tong, SUN Yao
2019, 39(10): 1075-1080. doi:10.15918/j.tbit1001-0645.2019.10.014
Abstract(788) PDF(414)
Abstract:
To overcome the influence of the interaction forces of human-robot on the trajectory tracking performance of rehabilitative training walker, a novel design method of observer was proposed based on position output of system to estimate the interaction forces of human-robot. Firstly, a nonlinear controller was designed and a system model was established for every motion axis to restrain the interaction forces and avoid larger tracking errors, in order to improve the system's tracking performance and guarantee the rehabilitee's safety. Further, taking the predictive control as a method to constrain the trajectory and velocity tracking errors simultaneously, the optimal trajectory tracking was realized for every motion axis. Finally, a simulation and experiment were carried out to analyze the running effect of the walker. Results show the effectiveness and advantage of the observation of human-robot interaction forces and the design method of controller.
Constant Rotation Ratio of Redundant Robot Manipulators Based on Neural Dynamics
WU Peng, MENG Xiang-yuan, WANG Zi-ye, GAO Jian-wei
2019, 39(10): 1081-1085. doi:10.15918/j.tbit1001-0645.2019.10.015
Abstract(981) PDF(316)
Abstract:
In this paper, a constant rotation ratio (CRR) algorithm based on neural dynamics was proposed to solve the trajectory accuracy of motion planning for redundant robot manipulators. In the motion planning, the pseudo-inverse of the Jacobian matrix was solved by the neural dynamics network solver. The real-time and accurate joint velocity was acquired by the fourth-order Runge-Kutta methods to solve the average velocity ratio of each joint, and to obtain the optimal joint angle for the CRR. Differing from the traditional motion planning by weighted pseudo-inverse solution, the CRR algorithm was designed to solve at the joint angle level, being the key approach to improve the trajectory accuracy of redundant robot manipulators. In addition, computer-simulation models with three-link and six-link planar robot manipulators were established. Simulation results show the validity of the CRR based on neural dynamics algorithm.
A Hidden Sentiment Detection Method Based on Hawkes Process
XIANG Nan, ZHANG Ming-min, YANG Li-li
2019, 39(10): 1086-1090. doi:10.15918/j.tbit1001-0645.2019.10.016
Abstract(963) PDF(458)
Abstract:
In order to simulate the dynamic transformation process of emotion effectively and detect the hidden sentiment of individuals in the interaction process, so as to improve the intelligence of virtual interaction process, a Hawkes process was used to simulate the process of individual emotion generation and decline firstly. Then the individual's expression was detected by the hidden Markov model and mapped to the dimensional space of the emotional model. Finally, the sentiment of the individual was derived by comparing the emotional states that observed after and before the event stimulus. In the case when an individual hidden the emotional states, a strategy, continually appending positive stimulation to the individual, was introduced to activate the emotional expressions, and adopted the negative as the default sentiment for the unsuccessful detection of the emotional expressions. Experiments show that, this method can effectively calculate individual's hidden sentiment and improve the intelligence of interaction.
Hardware-in-the-Loop Simulation for Position Control of Hydraulic Cylinder Using High Speed On/Off Valve
GAO Qiang, ZHU Yu-chuan, LUO Zhang, WANG Rui, SONG Yun-ze, CHEN Xiao-ming
2019, 39(10): 1091-1096. doi:10.15918/j.tbit1001-0645.2019.10.017
Abstract(871) PDF(340)
Abstract:
In order to study the position control of hydraulic cylinder using high speed on/off valve (HSV), a hydraulic loop was designed based on HSV and directional valve for the hydraulic cylinder control, and pulse width modulation (PWM) was used to drive the HSV. An off-line simulation model of the control system was established with simulink software, and the simulation of position tracking was carried out by PID with Kalman filter. A test bench of system was established for hardware-in-the-loop simulation based on Matlab/xPC target. The simulation and experimental results show that the proposed system structure is correct and the proposed control algorithm can achieve high precision of hydraulic position, and the efficiency of control system's design can be improved by hardware-in-the-loop simulation.
Synthesis of High Content of L-Lactide with Long Crystals
LIU Yang, HU Bin, GONG Cheng-lin, WANG Xiu-mei, MA Jian-yang, ZHANG Qi
2019, 39(10): 1097-1100. doi:10.15918/j.tbit1001-0645.2019.08.018
Abstract(995) PDF(355)
Abstract:
In order to obtain D,L-lactide with higher content of L-lactide, the optimum conditions for the synthesis of D,L-lactide by vacuum distillation were studied. Investigating and studying the catalyst selection and dosage, reaction time, reaction temperature and other processes, the optimal process conditions for lactide were determined. Polymerization was carried out under optimized reaction conditions, obtaining a long strip of D,L-lactide crystals with a crystal length of about 5~10 μm. The content of L-lactide in the mixture can be up to 76.5%.

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