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Guo Q.,Dalian University of Technology | Guo X.,Dalian University of Technology | Fan J.,Aircraft Strength Research Institute | Syed R.,Dalian University of Technology | Wu C.,Dalian University of Technology
International Journal of Fatigue | Year: 2015

Abstract The present paper, firstly, establishes a calculation model of intrinsic dissipation, based on the double exponential regression for the one-dimensional distribution of specimen surface temperature variation. Then, an energy method is proposed for rapid evaluation of high-cycle fatigue parameters (i.e., fatigue limit and S-N curve). The energy method takes intrinsic dissipation as the fatigue damage indicator, and eliminates the interference of internal friction causing no damage on fatigue life evaluation. An experimental research on FV520B stainless steel was performed, in order to verify the feasibility and validity of the energy method, as well as the calculation model. © 2015 Elsevier Ltd.

Liu B.,CAS Beijing Institute of Acoustics | Zhang H.,CAS Beijing Institute of Acoustics | Qian Z.,CAS Beijing Institute of Acoustics | Chang D.,CAS Beijing Institute of Acoustics | And 2 more authors.
Applied Acoustics | Year: 2014

The influence of stiffeners on plate vibration and noise radiation induced by turbulent boundary layers is investigated by wind tunnel measurements. Plates with and without stiffeners are tested under the flow speed of 60 m/s, 71 m/s and 86 m/s, respectively. The stiffeners are set either perpendicular or parallel to the direction of the free stream. Measured vibration and noise levels are compared with theoretical calculations, where wall pressure cross-spectra are described by the Corcos model. For the plates tested, it is evident that stiffeners perpendicular to the direction of the free stream could increase noise radiation, but have almost no influence on vibration level of plates. © 2013 Elsevier Ltd. All rights reserved.

Zhou K.,Nanjing University of Aeronautics and Astronautics | Chen P.,Nanjing University of Aeronautics and Astronautics | Chai Y.,Aircraft Strength Research Institute
Fuhe Cailiao Xuebao/Acta Materiae Compositae Sinica | Year: 2012

In an aircraft structure, it is often necessary to runout some of the stiffeners to satisfy detailed design requirements. Depending on the structural design, stiffeners for a wing structure may terminate at a chord-wise splice, at the forward or rear spar, at a rib, or at a structural discontinuity, such as an access hole. But an abrupt stiffener termination can cause highly localized bending gradients due to stiffness discontinuities and load-path centricities. In this paper, both experiment tests and FEM models relating to three different stiffener runout specimens were presented and the failure modes of these specimens were discussed in detail. In tension, the failure is deduced by peel stress and interlaminar shear stress. In compression, the failure is deduced by interlaminar shear stress only.

Kong B.,Nanjing University of Aeronautics and Astronautics | Ye Q.,Nanjing University of Aeronautics and Astronautics | Chen P.,Nanjing University of Aeronautics and Astronautics | Chai Y.,Aircraft Strength Research Institute
Fuhe Cailiao Xuebao/Acta Materiae Compositae Sinica | Year: 2010

The post-buckling induced failure process was simulated by using the cohesive element in the commercial software ABAQUS. The internal forces on the flange/skin interface were extracted from FEM results, and then their features were studied. The flange thickness was considered as a parameter to build a parameterized model for studying the effect of stiffness ratios of the flange to the skin on the interface debonding. The relationship among each component of the internal forces was also investigated. Failure criteria and failure envelops were developed for the flange/skin interface debonding. Finally the design parameters of the thickness ratio and the stiffness ratio between the flange and the skin were suggested for the design.

Kong B.,Nanjing University of Aeronautics and Astronautics | Ye Q.,Nanjing University of Aeronautics and Astronautics | Chen P.,Nanjing University of Aeronautics and Astronautics | Chai Y.,Aircraft Strength Research Institute
Fuhe Cailiao Xuebao/Acta Materiae Compositae Sinica | Year: 2010

The load transfer mechanisms at the post-buckling stage were studied for an integrated stiffened composite panel subjected to uniaxial compression. An FEM model was created for the panel by using the commercial software ABAQUS. The post-buckling process of the panel was simulated under uniaxial compression. The internal resultant forces and the load transfer mechanisms were discussed in detail at different stages (i. e., the local and global post-buckling). The distributions for resultant forces and moments at nodal and anti-nodal lines were obtained. The simulations agree well with experimental data. Finally it is indicated that the nodal and anti-nodal lines are possibly the first debonding locations of the flange/skin interface at the post-buckling stage and the forces crucial for failure are identified as Mxy and My.

Zheng X.,Northwestern Polytechnical University | Shen Z.,Aircraft Strength Research Institute | Yang S.,Aircraft Strength Research Institute
Hangkong Xuebao/Acta Aeronautica et Astronautica Sinica | Year: 2010

Through a series of drop-weight impact tests and quasi-static indentation (QSI) tests of composite laminates, three kinds of relationships are obtained between the impact energy (or the quasi-static indentation force) and the damage area, damage width or dent depth. An analysis of these relationships indicates clearly that, as compared with damage area or damage width, the dent depth is the most appropriate parameter to describe the damage. Therefore, the dent depth is selected as the damage parameter to set up the damage relationship between drop-weight impact and quasi-static indentation. Knee-point means the maximal ability of damage resistance for drop-weight impact and quasi-static indentation, and the two knee-points are very close for the two types of tests, which suggests the feasibility for setting up an equivalent relationship between them. By numerical analysis of the impact energy and static indentation force under the same dent depth, a new equivalent formula is set up, which corresponds well with the results of the tests. And it may provide theoretical support for damage tests in future.

Liu X.,Northwestern Polytechnical University | Zhou S.,Aircraft Strength Research Institute | Ma J.,Aircraft Strength Research Institute | Sun X.,Northwestern Polytechnical University | And 2 more authors.
Hangkong Xuebao/Acta Aeronautica et Astronautica Sinica | Year: 2012

A finite element crash model of a typical civil airplane sub-cabin structure is developed and then a structural energy absorption analysis is conducted with the LS-Dyna code. An energy absorption design method is introduced based on energy absorption structure concept to minimize the cabin floor acceleration response. Then a full-scale test article is designed and manufactured, and a drop test is conducted to verify the design features and the modeling method. A correlation evaluation method based on energy is introduced, and the finite element model is updated after the correlation analysis between the pre-test analysis results and the test results. The updated analysis results show good agreement with the test results. The error of the average peak acceleration response at the centroid of the simulated occupant is 16.44%, and the error of the average maximum rebound velocity of the model is 10.53%. The global deformation modes of the test and simulation also fit well. But the error of the energy absorption duration and time when the peak acceleration appears are fairly large, which indicates that certain structural modeling features, such as the structural joint dynamic failure mode, have significant impact on the computational results.

Zhang W.,Aircraft Strength Research Institute | Dong D.,Aircraft Strength Research Institute
Jixie Qiangdu/Journal of Mechanical Strength | Year: 2013

LY12CZ panels with single middle crack are tested under constant-amplitude load to validate the availability of simulation based on FRANC2D/L. The results show that the simulation agree with the test results. Five finite element cracking models, including equal-length cracks of multiple holes, lord crack of multiple holes, adjacent cracks of multiple holes, non-adjacent cracks of multiple holes, single crack, are built by FRANC2D/L to study the distribution of stress intensity factors and crack propagation life. The numerical simulation results indicate that the interference effects between cracks become more and more obvious as the cracks increase. And the crack propagation life of the middle crack is commonly less than that of the sideward crack.

Wei W.,Xi'an University of Arts and Science | Zhao X.Y.,Aircraft Strength Research Institute
Advanced Materials Research | Year: 2013

The point-to-point swing arm test is very important for large arms which have swing arm movement. Traditional point-to-point swing arm controller is relay control mode. The mode has many shortcomings, such as big volume, high power consumption, low stability, and so on. An intelligent point-to-point swing arm controller, using MCU as the control core, was designed for this reason. It was mainly composed of switch signal detecting module, solenoid valve drive module, USB storage interface module and MCU control module. According to the requirements of test, the controller was able to detect the valid signal of limit switch and control commutation operation of solenoid valve, meanwhile it could record the movement time between one point and another point, the time the arm swayed and the moment information, and these above information would be stored in USB memory. It has some advantages of small size, low power consumption, high stability and flexible functions. © (2013) Trans Tech Publications, Switzerland.

Fan J.,Aircraft Strength Research Institute
Hangkong Cailiao Xuebao/Journal of Aeronautical Materials | Year: 2016

During the actual engineering application, it is conservative and costly to estimate the detail fatigue rating (DFR) of structures by using the Goodman model. A calculation formula based on the Gerber model was derived to estimate the DFR value (stress ratio R=0.06), and a detail effect coefficient was introduced to analyze the influence of more details on the confidence coefficient and estimated DFR value. Through the comparison with the existed results, it is found that the developed method for the DFR value estimation based on the Gerber model can extent the material potential and reduce the development cost greatly. Finally, according to the detail rating coefficient of the component, the DFR values of structures with more details are estimated by use of the DFR values of structures with single detail. The comparison between the estimated results and the testing results has validated the correctness and applicability of the derived DFR method based on the Gerber model. © 2016, Chinese Journal of Aeronautics. All right reserved.

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