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Huang A.,Huazhong University of Science and Technology | Zhang H.,Huazhong University of Science and Technology | Liu J.,Huazhong University of Science and Technology | Yu W.,Huazhong University of Science and Technology | And 2 more authors.
Advanced Materials Research | Year: 2011

Laser welding of 1A90 pure aluminum and ZL114A aluminum alloy with powder under the same laser welding parameters were carried out in this work. The relation between weld elements and solidification cracking formation of these two materials was investigated in the perspective of metallurgical factor. And the alloy element contents and distribution near the cracks were determined by scanning electron microscope (SEM) and energy-dispersive X-ray spectroscopy (EDS). Then the concept of weld element equivalent was introduced comparing with the carbon equivalent expression. The weld element equivalent expressions were established by using mathematics regress. And the verified results indicate that the weld element equivalent expressions can properly forecast the formation of solidification cracking. © (2011) Trans Tech Publications, Switzerland. Source


Wang Y.,Beihang University | Li N.,University of Tennessee at Knoxville | Chen X.,COMAC Shanghai Aircraft Manufacturing Co. | Liu M.,CAS Shanghai Institute of Microsystem and Information Technology
Advances in Mechanical Engineering | Year: 2014

This paper presents design and implementation of an attitude and heading reference system (AHRS) based on low-cost MEMS sensors and complementary filtering (CF). Different from traditional solutions, information fusion is performed with Euler angles directly, which is more straightforward for understanding; however it proposes many challenges for reaching a stable and accurate estimation as when these angles approach or traverse their range boundaries, estimation may get discontinuous. Thus an effective discontinuity avoiding strategy is suggested in this paper to refine the estimation. Besides, instead of extended Kalman filtering (EKF), CF is utilized for state estimation of AHRS as it features fusion of high-frequency and low-frequency signals. In order to make up for shortcomings of MEMS sensors such as multiple errors, drifts, and bad accuracy, some effective calibration and filtering algorithms are proposed to guarantee agreeable AHRS performance. Also, architecture of the MEMS IMU (inertial measurement unit) and mathematical principles for AHRS solution are explained and implemented in this paper. Meanwhile, experimental comparisons have proved feasibility and acceptable performance of this AHRS design. Copyright © 2014 Yangzhu Wang et al. Source


Liu S.,Beihang University | Guan Z.,Beihang University | Guo X.,Beihang University | Yan D.,COMAC Shanghai Aircraft Manufacturing Co. | And 2 more authors.
Applied Mechanics and Materials | Year: 2012

An experimental and analytical study on ultimate tensile strength of composite double-lap joints with different adhesive thicknesses is employed in the paper,test results indicate the major failure mode of joints is adhesive shear failure and the ultimate strength of joints increasing with thicker adhesive. Analytical model is developed to investigate the adhesive failure of double-lap joint based on the experiments. The model takes into account anisotropy of each ply in the composite laminates and elastic-perfectly plastic behavior of the adhesive in the joints. The validity of analytical model for calculating shear strain/stress distribution is certified by comparing with finite model results. Maximum shear strain criterion is adopted in the analytical model to predict the ultimate tensile load of double-lap joint. Good agreement of the analytical predictions with the experimental results is obtained. © (2012) Trans Tech Publications, Switzerland. Source


Guo X.,Beihang University | Guan Z.,Beihang University | Liu S.,Beihang University | Kong J.,COMAC Shanghai Aircraft Manufacturing Co. | And 2 more authors.
Fuhe Cailiao Xuebao/Acta Materiae Compositae Sinica | Year: 2013

The flexural behavior of the repaired honeycomb sandwich structures, which were made up of carbon fiber reinforced polymer (CFRP) skins and honeycomb material, was investigated by four-point bending test. The bending performance of the repaired plate was analyzed under the influence of scarf ratio, flush repair method, damage size, repair equipment and repair material. The test results show that, the failure modes of all the repaired plate can be divided into three kinds: breaking at the edge of the patch, breaking at the middle of the patch and breaking at the adhesive film surface. The failure strength of the specimens with the same failure mode is close. The bending strength of the repaired plate of which the first two failure modes plate is similar to the undamaged plate, while the bending strength of the repaired plate of the third failure mode is relatively low. The strength recovery of all the repaired plate is basically higher than 95%. The analysis on the relative stiffness of sandwich structures shows that the stiffness of the repaired structures is close to the undamaged plate, which is consistent with the composite repair criterion. Source


Liu S.,Beihang University | Guan Z.-D.,Beihang University | Guo X.,Beihang University | Liu J.,COMAC Shanghai Aircraft Manufacturing Co. | And 3 more authors.
Hangkong Cailiao Xuebao/Journal of Aeronautical Materials | Year: 2012

An experimental and analytical study on ultimate tensile strength of composite double-lap joints with different adhesive thicknesses is employed in the paper, test results indicate the major failure mode of joints is adhesive shear failure and the ultimate strength of joints increasing with thicker adhesive. Analytical model is developed to investigate the adhesive failure of double-lap joint based on the experiments. The model takes into account anisotropy of each ply in the composite laminates and elastic-perfectly plastic behavior of the adhesive in the joints. The validity of analytical model for calculating shear strain/stress distribution is certified by comparing with finite model results. Maximum shear strain criterion is adopted in the analytical model to predict the ultimate tensile load of double-lap joint. Good agreement of the analytical predictions with the experimental results is obtained. Source

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