Papers by Author: Xiao Cong He

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Authors: Xiao Cong He
Abstract: This study deals with an application of the method of the coefficient of variation in strength prediction of the self-piercing riveted joints. Defined as the ratio of the standard deviation to the mean, the coefficient of variation may be used in both the reliability-based design of self-piercing riveted joints and in the evaluation of existing products. In this study, the concept and definition of the coefficient of variation are stated. The procedure of the use of coefficient of variation for approximate calculations of strength of the self-piercing riveted joints is presented and compared with the classical Taylor expansion method. This is illustrated with a numerical example.
334
Authors: Xiao Cong He
Abstract: The influence of adhesive layer thickness on the dynamic behaviour of the single-lap adhesive joints is investigated in this paper. The ABAQUS finite element analysis (FEA) software was used to predict the frequency response functions (FRFs) of the single-lap adhesive joints of different thickness of the adhesive layer. As a reference, the FRFs of a cantilevered beam without joint were investigated as well. It is clear that the FRFs of the four beams are close to each other within the frequency range 0~1000 Hz. It is also found that the composite damping of the single-lap adhesive joint increases as the thickness of the adhesive layer increases.
3920
Authors: Xiao Cong He
Abstract: Thispaperdealswithcomparisonsoffiniteelementmodelsofadhesivelybondedjoints. Inordertoincreasetheaccuracyoftheresults,fivelayersofsolidelementswereusedacrossthe adhesivelayerwhichwasonly0.05mminthickness.Thefiniteelementswererefinedgraduallyin steps from adherends to adhesive layer. In these models, most regions of the adherends and adhesiveweremodelledusingsolidbrickelementsbutsomesolidtriangularprismelementswere usedforasmoothtransition.Insomeofthemodels,linearinterpolationelementsoffullorreduced integrationandofhybridformulationwereused.Inothermodels,quadraticinterpolationelements of full or reduced integration and of hybrid formulation were used. Comparisons are performed betweenmodelswithdifferentmodellingapproachinordertofindasuitablemodeltopredictthe mechanicalbehaviourofadhesivelybondedjoints.
2192
Authors: Xiao Cong He
Abstract: The aim of this study is to predict the dynamic behaviour of single lap-jointed cantilevered beams theoretically and to validate the predictions via experimental tests. The ABAQUS finite element analysis (FEA) software was used to predict the natural frequencies, mode shapes and frequency response functions (FRFs) of lap-jointed beams. The LMS (Leuven Measurement System) CADA-X dynamic test software and the LMS-DIFA Scadas II 48 channel data acquisition hardware were used in experimental measurement of the dynamic response of the lap-jointed beams. It is shown that the natural frequencies of the single lap-jointed cantilevered beams from experiment are lower than those predicted using FEA. It is also found that the measued FRFs are close to the predicted FRFs for the first two modes of vibration of the single lap-jointed cantilevered beam. Above the second mode of vibration, there is considerable discrepancy between the measured and predicted FRFs.
733
Authors: Xiao Cong He
Abstract: The aim of this paper is to investigate the effect of supports on the actual stress distribution of the single-lap adhesive joints under tension using the three-dimensional finite element methods. Five layers of elements were used across the adhesive thickness in order to obtain an accurate indication of the variation of stresses. All the numerical results obtained from the finite element analysis show that the spatial distribution of all components of stress are similar for different interfaces though the stress values are obviously different. The results also show that most of the maximum stresses occur at the interface 1. It can be seen from the results that the stresses are concentrated near the left free ends of the adhesive layer while the centre region of the adhesive layer is mostly stress-free.
1495
Authors: Xiao Cong He
Abstract: Adhesive bonding is a high-speed fastening technique which is suitable for joining advanced lightweight sheet materials that are dissimilar, coated and hard to weld. Major advances have been made in recent years in adhesive bonding technique. Latest literature relating to finite element analysis (FEA) of adhesively bonded single-lap joints (SLJs) is reviewed in this paper. The recent development in FEA of SLJs is described with particular reference to three major factors that influence the success of adhesive bonding technique: failure mechanism, environmental effects and mechanical behavior. The main FE methods used in FEA of SLJs are discussed and illustrated with brief case studies from the literature. Areas where further useful progress can be made are also identified.
411
Authors: Xiao Cong He, Ian Pearson, Ken W. Young
Abstract: Self-pierce riveting (SPR) is a sheet material joining technique which is suitable for joining dissimilar materials, as well as coated and pre-painted materials. Published work relating to finite element analysis of SPR joints is reviewed in this paper, in terms of process, static strength, fatigue strength, vibration characteristics and assembly dimensional prediction of the SPR joints. A few important numerical issues are discussed, including material modelling, meshing procedure, failure criteria and friction between substrates and between rivet and substrate. It is concluded that the finite element analysis of SPR joints will help future applications of SPR by allowing system parameters to be selected to give as large a process window as possible for successful joint manufacture. This will allow many tests to be simulated that would currently take too long to perform or be prohibitively expensive in practice, such as modifications to rivet geometry, die geometry or material properties. The main goal of the paper is to review recent progress in finite element analysis of SPR joints and to provide a basis for further research.
663
Authors: Xiao Cong He
Abstract: The aim of this study is to investigate the creep-fatigue behavior of stainless steel materials. Based on the elevated-temperature tensile, creep and rupture test data, thermal creep-fatigue modelling was conducted to predict the failure life of stainless steels. In the low cycle thermal fatigue life model, Manson’s Universal Slopes equation was used as an empirical correlation which relates fatigue endurance to tensile properties. Fatigue test data were used in conjunction with different modes to establish the relationship between temperature and other parameters. Then creep models were created for stainless steel materials. In order to correlate the results of short-time elevated temperature tests with long-term service performance at more moderate temperatures, different creep prediction models, namely Basquin model, Sherby-Dorn model and Manson-Haferd model, were studied. Comparison between the different creep prediction models were carried out for a range of stresses and temperatures. A linear damage summation method was used to establish life prediction model of stainless steel materials under creep-fatigue.
725
Authors: Xiao Cong He, Yue Bo Hu, Bao Ying Xing, Yan Fang Ding, Kai Zeng
Abstract: The need to create lighter vehicles to aid in reducing emissions and increase fuel efficiency has become increasingly important in recent years. Self-pierce riveting (SPR) has drawn more attention as it can join some advanced materials that are dissimilar and hard to weld. In present study, the SPR process has been numerically simulated using the commercial finite element (FE) software LS-Dyna. For validating the numerical simulation of the SPR process, experimental tests on specimens made of aluminium alloy have been carried out. The online window monitoring technique was used in the tests for evaluating the quality of SPR joints. Good agreements between the simulations and the tests have been found, both with respect to the force-travel curves as well as the deformed shape on the cross-section of SPR joint.
1765
Authors: Xiao Cong He
Abstract: In present paper, sensitivity study on parameters for fatigue-creep model of stainless steel materials has been carried out. An analytical model has been established to predict fatigue-creep life of AISI347 stainless steel. Manson’s Universal Slopes equation has been used as an empirical correlation which relates fatigue endurance to tensile properties. Different creep prediction models have been studied in order to correlate the results of shout-time elevated temperature tests with long-term service performance at more moderate temperatures. Comparison between the different creep prediction models and experimental results were carried out for a range of stresses and temperatures. A linear damage summation method has been used to combined fatigue and creep. The results of sensitivity analysis indicate that strain range and temperature have very significant influence on creep-fatigue life estimation.
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