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Wei W.,Xian University of Arts and Science | Zhao X.,Aircraft Strength Research Institute of China | Zhao X.,Fatigue Laboratory
International Review on Computers and Software | Year: 2012

An intelligent capacitor and inductor measuring instrument with intelligent AC parameters is developed. The key used technologies are the capacitance (inductance)-voltage conversion principle and STC89C52 MCU. The measuring data is from A/D conversion to STC89C52 MCU, and then being sent to monitor for display. Compared with the traditional measuring instrument, it has the advantages of digital display, simple operation and automatic measurement. In addition, compared with the other digital measuring instrument, the proposed instrument has the advantages of high precision and low cost. © 2012 Praise Worthy Prize S.r.l. - All rights reserved.

Zhao H.-J.,Xian University of Architecture and Technology | Dong N.-J.,Aircraft Strength Research Institute of China | Liu C.,Xian University of Architecture and Technology | Wu M.-Z.,Xian University of Architecture and Technology
Gongcheng Lixue/Engineering Mechanics | Year: 2011

Based on the dynamic stability theory of an elastic system, parametric vibration equations of laced and battened lattice columns subject to a periodic load under high temperature (fire) condition were established respectively by adopting the energy method and Hamilton principle. Galerkin's method was used to convert the partial differential equations into second order ordinary differential Mathieu equations, and then the dynamic instability regions surrounded by periodic solutions were obtained. The dynamic stability problems of parametric vibration were discussed about two kinds of axial compression lattice columns. Through analyzing the influences of slenderness ratio, constant load and temperature etc. on the dynamic instability regions of axial compression lattice column, reference basis for the dynamic analysis and design on high temperature (fire) condition in structure engineering is provided.

Ye Q.,Nanjing University of Aeronautics and Astronautics | Wang R.,Nanjing University of Aeronautics and Astronautics | Chen P.,Nanjing University of Aeronautics and Astronautics | Shen Z.,Aircraft Strength Research Institute of China
Fuhe Cailiao Xuebao/Acta Materiae Compositae Sinica | Year: 2012

A method was developed to predict numerically the dent depth of composite laminates subjected to quasi-static indentation. A progressive damage analysis was conducted for composite laminates under quasi-static transverse compressive loading by using a strain based Hashin and Yeh failure criteria as well as the FEM, and a series of degraded elastic constants of the damaged zone were drawn from the numerical results. The effective elastic constants of the damaged zone of the laminates were evaluated according to Sun's explicit expression. Finally, the dent depth vs. indentation force curve was predicted based on Turner's contact theory. The numerical results indicate that the dent initiation is induced by the matrix cracking and delamination, and the transition to rapid increase in dent depth is due to the fiber breakages. The numerical results agree well with the test data for the delamination onset load, the maximum contact force and the corresponding dent depth.

Zhang A.,Aircraft Strength Research Institute of China | Qiu X.,Chengdu Aircraft Design Research Institute
Yingyong Lixue Xuebao/Chinese Journal of Applied Mechanics | Year: 2015

In order to investigate the mechanism of composite failure so as to provide analysis basis for strength designing, structure failure simulation is necessary. In the process of static general failure analysis, material decay often causes severe convergence problems. Dynamic explicit analysis can well model material breakage. In this paper, the mechanical response of multi-wall box under bending load case is simulated using dynamic explicit analysis method. Panel and wall are modeled with shell element. A solid geometry is introduced to the half-thickness of the up-panel to simulate inter-laminar damage. The VUMAT subroutine is adopted to degrade material stiffness consecutively while damage occurred. It is shown that dynamic explicit analysis can well simulate the damage process of the box. Analysis results including strain, buckling load, failure load and collapse mode are in good agreement with test results. The errors of predicted buckling load and failure load are within 7%, which shows the method is satisfactory to engineering design. ©, 2015, Xi'an Jiaotong University. All right reserved.

Han Q.-N.,Tsinghua University | Han Q.-N.,Aircraft Strength Research Institute of China | Qiu W.,Tsinghua University | Shang Y.-B.,Tsinghua University | Shi H.-J.,Tsinghua University
Tribology International | Year: 2016

Fretting fatigue behavior of Ni-base single crystal (NBSX) superalloys was investigated based on in-situ scanning electron microscope (SEM) observations. Evolutions of slip lines and initiations of cracks were observed. Slip lines were found on specimen free surface along three typical directions. Short cracks were observed to initiate along the slip line. Crystal plasticity constitutive model considering cyclic hardening effect was employed. Crystal plasticity finite element method (CPFEM) simulation showed the activations of crystallographic slip systems at contact region. The slip plane with the maximum plastic slip was determined as dominate slip plane. Equivalent plastic strain was proved effective to predict crack initiation. The simulation results including predicted slip lines, crack initiation locations and orientations were in good agreements with observations. © 2016 Elsevier Ltd. All rights reserved.

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