1.

PREDICTION OF FATIGUE LIVES OF RC BEAMS STRENGTHENED WITH CFL UNDER RANDOM LOADING





Rongwei Lin Peiyan Huang Chen Zhao Xinyan Guo Xiaohong Zheng《Acta Mechanica Solida Sinica》,2008年第21卷第4期


The investigation on fatigue lives of reinforced concrete （RC） structures strength ened with fiber laminate under random loading is important for the repairing or the strengthening of bridges and the safety of the traffic. In this paper, two methods are developed for predicting the fatigue lives of RC structures strengthened with carbon fiber [aminate （CFL） under random loading based on a residual life and a residual strength model. To discuss the efficiency of the model, 12 RC beams strengthened with CFL are tested under random loading by the MTS810 testing system. The predicted residual strength approximately agrees with test results.

2.

Fatigue damage rule of LY12CZ aluminium alloy under sequential biaxial loading





WANG YingYu ZHANG DaChuan YAO WeiXing《中国科学:物理学 力学 天文学(英文版)》,2014年第57卷第1期


A series of biaxial twolevel variable amplitude loading tests are conducted on smooth tubular specimens of LY12CZ aluminium alloy.The loading paths of 90°outofphase,45°outofphase and 45°inphase are utilized.The fatigue damage cumulative rules under twolevel step loading of three loading paths are analyzed.By introducing a parameter which is a function of the phase lag angle between the axial and the torsional loading,a new multiaxial nonlinear fatigue damage cumulative model is proposed.The proposed model is evaluated by the experimental data for twolevel loading,multilevel loading of LY12CZ aluminium alloy,and multilevel loading of 45 steel.Fatigue lives predicted are within a factor of 2 scatter band.

3.

STUDY ON THE SURFACE CRACK GROWTH BEHAVIOR IN 14MnNbq BRIDGE STEEL





Yanping Liu Chuanyao Chen Guoqing Li《Acta Mechanica Solida Sinica》,2010年第23卷第4期


Threedimensional crack closure correction methods are investigated in this paper.The fatigue crack growth tests of surface cracks in 14MnNbq steel for bridge plate subjected to tensile and bending loadings are systematically conducted.The experimentally measured fatigue crack growth rates of surface cracks are compared with those of throughthickness cracks in detail.It is found that the crack growth rates of surface cracks are lower than those of throughthickness cracks.In order to correct their differences in fatigue crack growth rates, a dimensionless crack closure correction model is proposed.Although this correction model is determined only by the experimental data of surface cracks under tensile loading with a constant ratio R=0.05, it can correlate the surface crack growth rates with reasonable accuracy under tensile and bending loadings with various stress ratios ranging from 0 to 0.5.Furthermore, predictions of fatigue life and crack aspect ratio for surface cracks are discussed, and the predicted results are also compared with those obtained from other prediction approaches.Comparison results show that the proposed crack closure correction model gives better prediction of fatigue life than other models.

4.

FATIGUE LIFE PREDICTION OF SUS 630 （H900） STEEL UNDER HIGH CYCLE LOADING





Fengming Guo Miaolin Feng Defu Nie Jinquan Xu Md. Shahnewaz Bhuiyan Yoshiharu Mutoh《Acta Mechanica Solida Sinica》,2013年第6期


The fatigue life prediction of high strength steel SUS 630 （H900） under high cycle loading is conducted with consideration of a characteristic fatigue length of material. Based on the WShler curve of smooth materials, a modified method for fatigue life prediction is approached. The characteristic fatigue length of material under cyclic loading is associated with the polycrystalline material. Rather than the stress at a point, the average stress within the characteristic fatigue length is implemented for the fatigue life prediction. The method can be applied to both the smooth and the defected material. The fatigue life prediction is also verified experimentally by specimens with various small circular holes. Through the comparison, it is found that the method can be adopted to predict the fatigue lives with different size effects.

5.

ENDOFEM INTEGRATED METHODOLOGY FOR FATIGUE CRACK GROWTH





C.F.Lee L.T.Hsiao《Acta Mechanica Sinica》,2002年第18卷第2期


In this paper, the FEM with the incremental endochronic cyclic plasticity (EndoFEM) and the rc controlled nodereleased strategy are employed to study the fatigue crack opened/closed load (Pop) of A1 2024T3 CCT specimens provided by Mageed and Pandey under several crack lengths and the constant amplitude with various load ratio (R). After statisfactory results are achieved by comparisons of computed Pop values and cited experimental data, the simulations will be extended to the crack lengths with significant bending effect due to short ligaments or high peak (Pmax) or high positive or very low negative R cyclic loads. Through these simulations, the complete map of Pop/Pmax vs. Kmax and R can be constructed and thereafter its correspondant empirical formulae can be proposed. Using these formulae and selecting the traditional fatigue crack growth parameter ΔKeff, the A1 2024T3 fatigue crack growth rate da/dN vs. ΔK and R data, provided by Hiroshi and Schijve, can be employed to proposed empirical formulae of da/dN vs. ΔKeff and R. After integration, fatiguecrackgrowth length a vs. N curves computed by EndoFEM can be obtained. The results are agreed very well with the existing experimental curves. According to the above procedures of simulation and steps of comparions with experiment, this paper may provides an integrate methodology of numerical simulation in the studies of fatigue crack growth for academic and industrial researches and design analysis.

6.

Peeling behavior and spalling resistance of CFRP sheets bonded to bent concrete surfaces





Hong Yuan·Faping Li MOE Key Lab of Disaster Forecast Control in Engineering Institute of Applied Mechanics Jinan University Guangzhou China《Acta Mechanica Sinica》,2010年第26卷第2期


In this paper, the peeling behavior and the spalling resistance effect of carbon fiber reinforced polymer （CFRP） sheets externally bonded to bent concrete surfaces are firstly investigated experimentally. Twenty one curved specimens and seven plane specimens are studied in the paper, in which curved specimens with bonded CFRP sheets can simulate the concrete spalling in tunnel, culvert, arch bridge etc., whereas plane specimens with bonded CFRP sheets can simulate the concrete spalling in beam bridge, slab bridge and pedestrian bridge. Three kinds of curved specimens with different radii of curvature are chosen by referring to practical tunnel structures, and plane specimens are used for comparison with curved ones. A peeling load is applied on the FRP sheet by loading a circular steel tube placed into the central notch of beam to debond CFRP sheets from the bent concrete surface, meanwhile fullrange loaddeflection curves are recorded by a MTS 831.10 Elastomer Test System. Based on the experimental results, a theoretical analysis is also conducted for the specimens. Both theoretical and experimental results show that only two material parameters, the interfacial fracture energy of CFRPconcrete interface and the tensile stiffness of CFRP sheets, are needed for describing the interfacial spalling behavior. It is found that the radius of curvature has remarkable influence on peeling loaddeflection curves. The test methods and test results given in the paper are helpful and available for reference to the designer of tunnel strengthening.

7.

ADVANCES IN TRANSFORMATION RATCHETING AND RATCHETINGFATIGUE INTERACTION OF NITI SHAPE MEMORY ALLOY





Guozheng Kang《Acta Mechanica Solida Sinica》,2013年第26卷第3期


The accumulation of inelastic deformation occurring in NiTi shape memory alloy under the stresscontrolled cyclic loading condition is named transformation ratcheting, since it is mainly caused by the solidsolid transformation from austenite to martensite phase and vice versa. The transformation ratcheting and its effect on the fatigue life (i.e., transformationfatigue interaction) are key issues that should be addressed in order to assess the fatigue of NiTi shape memory alloy more accurately. In this paper, the advances in the studies on the transformation ratcheting and ratchetingfatigue interaction of superelastic NiTi shape memory alloy in recent years are reviewed: First, experimental observation of the uniaxial transformation ratcheting and ratchetingfatigue interaction of superelastic NiTi alloy under the stresscontrolled cyclic loading conditions is treated, and the detrimental effect of transformation ratcheting on the fatigue life is addressed; Secondly, two types of cyclic constitutive models (i.e., a macroscopic phenomenological model and a micromechanical one based on crystal plasticity) constructed to describe the transformation ratcheting of superelastic NiTi alloy are discussed; Furthermore, an energybased failure model is provided and dealt with by comparing its predicted fatigue lives with experimental ones; Finally, some suggestions about future work are made.

8.

EFFECT OF LOADING TYPE ON FATIGUE CRACK GROWTH BEHAVIOR OF SOLDER JOINT IN ELECTRONIC PACKAGING





Xishu Wang ;Huaihui Ren ;Bisheng Wu ;Su Ja ;Norio Kawagoishi《Acta Mechanica Solida Sinica》,2014年第3期


Fatigue cracking tests of a solder joint were carried out using insitu scanning electron microscopy （SEM） technology under tensile and bending cyclic loadings. The method for predicting the fatigue life is provided based on the fatigue crack growth rate of the solder joint. The results show that the effect of the loading type on the fatigue crack growth behavior of a solder joint cannot be ignored. In addition, the finite element analysis results help quantitatively estimate the response relationship between solder joint structures. The fatigue crack initiation life of a solder joint is in good agreement with the fatigue life （N50%） of a totally electronic board with 36 solder joints.

9.

Damage evaluation of reinforced concrete frame based on a combined fiber beam model





SHANG Bing LIU ZhanLi ZHUANG Zhuo《中国科学:物理学 力学 天文学(英文版)》,2014年第57卷第4期


In order to analyze and simulate the impact collapse or seismic response of the reinforced concrete(RC)structures,a combined fiber beam model is proposed by dividing the cross section of RC beam into concrete fiber and steel fiber.The stressstrain relationship of concrete fiber is based on a model proposed by concrete codes for concrete structures.The stressstrain behavior of steel fiber is based on a model suggested by others.These constitutive models are implemented into a general finite element program ABAQUS through the user defined subroutines to provide effective computational tools for the inelastic analysis of RC frame structures.The fiber model proposed in this paper is validated by comparing with experiment data of the RC column under cyclical lateral loading.The damage evolution of a threedimension frame subjected to impact loading is also investigated.

10.

COMPUTATION OF FLEXURAL PROPERTIES OF HA/PLLA COMPOSITE USING A CELL MODEL APPROACH





Fan Jianping Tang ChakYin Tsui C.P.《Acta Mechanica Solida Sinica》,2006年第19卷第1期


A threedimensional finite element analysis was conducted to evaluate the feasibility of predicting the flexural properties of hydroxyapatitereinforced polyLlactide acid (HA/PLLA) biocomposite using three different schemes. The scheme 1, originated from a beam analysis, was used to determine the flexural modulus analytically while the scheme 2 and 3 were designed to have different loading and boundary conditions using a finite element cell modeling approach. An empirical approach using Chow's formula and experimental data were used for comparison with the predicted results. In order to reduce the computational time and save the storage space involved in determining the effect of varying particle volume fractions on the flexural properties of HA/PLLA, a superelement technique was applied. The results using the scheme 3 and the Chow's formula were found to be in reasonable agreement with experimental results over the range of particle volume fraction. In addition to the Chow's formula, local stress distribution and the failure processes in HA/PLLA were simulated using the finite element technique.

11.

Fatigue damage behavior of a surfacemount electronic package under different cyclic applied loads





任淮辉 王习术《中国物理 B》,2014年第4期


This paper studies and compares the effects of pullpull and 3point bending cyclic loadings on the mechanical fa tigue damage behaviors of a solder joint in a surfacemount electronic package. The comparisons are based on experimental investigations using scanning electron microscopy （SEM） insitu technology and nonlinear finite element modeling, respec tively. The compared results indicate that there are different threshold levels of plastic strain for the initial damage of solder joints under two cyclic applied loads; meanwhile, fatigue crack initiation occurs at different locations, and the accumulation of equivalent plastic strain determines the trend and direction of fatigue crack propagation. In addition, simulation results of the fatigue damage process of solder joints considering a constitutive model of damage initiation criteria for ductile materials and damage evolution based on accumulating inelastic hysteresis energy are identical to the experimental results. The actual fatigue life of the solder joint is almost the same and demonstrates that the FE modeling used in this study can provide an accurate prediction of solder joint fatigue failure.

12.

INVESTIGATION OF FRACTURE DESIGN FOR MEDIUM CARBON STEEL UNDER EXTRALOW CYCLIC FATIGUE IN AXIAL LOADING





Youtang Li Shuai Tan Hongyan Duan《Acta Mechanica Solida Sinica》,2008年第21卷第4期


The extralow cyclic fracture problem of medium carbon steel under axial fatigue loading was investigated. Several problems, such as the relations of the cycle times to the depth and tip radius of the notch, loading frequency, loading range and the parameters of fracture design for medium carbon steel on condition of extralow axial fatigue loading were discussed based on the experiments. Experimental results indicated that the tensionpressure fatigue loading mode was suitable for extralow cyclic fatigue fracture design of medium carbon steel and it resulted in low energy consumption, fracture surface with high quality, low cycle times, and high efficiency. The appropriate parameters were as follows： loading frequency 35 Hz, notch tip radius r = （0.20.3） mm, opening angle α = 60°, and notch depth t = （0.140.17）D.

13.

FATIGUE CRACK PROPAGAION UNDER MIXED MODE LOADING





曹桂馨 琚定一《应用数学和力学(英文版)》,1984年第2期


Mixed model fatigue crack propagation is analyzed in this paper, using a centre cracked plate geometry, loaded under uniaxial cyclic tension. Based on maximum principal stress criterion, a modified Paris expression of fatigue crack growth rate is derived in terms of ΔΚ and crack angle β_0 for an inclined crack. It is also shown that it is more convenient to express the Paris equation by means of crack length projected on the x axis, a_x rather than the actual length, a itself. The crack trajectory due to cyclic loading is predicted. β_0 is varied from 29°to 90°. Experimental data on Type L3 aluminium agree fairly well with predicted values when β_0 exceeds 30°.

14.

Calculation of doubleβ decay halflives using an improved PrimakoffRosen formula





《中国物理C(英文版)》,2021年第8期


A systematic analysis on experimental data of the halflives of nuclear doubleβ decays with two neutrinos(2vββ) is performed based on the analytical formula proposed by Primakoff and Rosen.We improve the formula by considering the shell effects and refining the energy dependence of the phasespace factor.This improved formula can closely describe all available experimental halflives of 2vβ~β~decays,both for groundstate transitions and transitions from ground states of parent nuclei to the first 0~+ excited states of daughter nuclei.The calculated halflives agree with the experimental data of groundstate transitions of all known eleven nuclei with an average factor of 2.3.Further predictions are provided for 2vββdecay candidates with decay energies above 0.5 MeV.We compare different theoretical predictions and emphasize the importance of experimental measurements on the halflives of doubleβ transitions between the ground state of ~(48)Ca,~(76)Ge,and ~(136)Xe and the first 0~+ excited states of their corresponding daughter nuclei,which will be very useful for understanding the underlying mechanisms of doubleβ decays and for further studying the shell effects on nuclear transition matrix elements.

15.

Isospin effect on spontaneous fission halflives of eveneven nuclei





陈玉庆 任中洲 许昌 郭艳青《中国物理 C》,2008年第32卷第Z2期


By using a new fiveparameter formula derived from the WKB approximation, we systematically calculate the spontaneous fission halflives of eveneven nuclei with Z=90—108. The isospin effect is taken into account in the new formula. The calculated halflives agree well with the experimental data. In addition, we predict the spontaneous fission halflives of superheavy nuclei with Z=108—114. Our predictions may provide references for future experiments.

16.

Fatigue crack growth in fibermetal laminates





MA YuE XIA ZhongChun XIONG XiaoFeng《中国科学:物理学 力学 天文学(英文版)》,2014年第57卷第1期


Fibermetal laminates(FMLs)consist of three layers of aluminum alloy 2024T3 and two layers of glass/epoxy prepreg,and it(it means FMLs)is laminated by Al alloy and fiber alternatively.Fatigue crack growth rates in notched fibermetal laminates under constant amplitude fatigue loading were studied experimentally and numerically and were compared with them in monolithic 2024T3 Al alloy plates.It is shown that the fatigue life of FMLs is about 17 times longer than monolithic 2024T3 Al alloy plate;and crack growth rates in FMLs panels remain constant mostly even when the crack is long,unlike in the monolithic 2024T3 Al alloy plates.The formula to calculate bridge stress profiles of FMLs was derived based on the fracture theory.A program by Matlab was developed to calculate the distribution of bridge stress in FMLs,and then fatigue growth lives were obtained.Finite element models of FMLs were built and meshed finely to analyze the stress distributions.Both results were compared with the experimental results.They agree well with each other.

17.

A STUDY OF CRACK CLOSURE IN ELECTRICFIELDINDUCED FATIGUE IN FERROELECTRIC CERAMICS





Zhang Zhenke Fang Daining 《Acta Mechanica Solida Sinica》,2003年第16卷第1期


Considering the influence of the domain switching near the tip of a crack and applying the idea of multiscale singularity fields in piezoelectric fracture,we have obtained an empiricalcriterion for the crack closure.Based on the domain switching in the electric yield region,referringto Yang's results on the small scale yield model for the electrical fatigue crack,a model of thecrack closure during electricfieldinduced fatigue is developed to analyze the crack growth.Interms of the model we have obtained the formula of the rate of the crack growth under cyclicelectric loading.Finally we compare the theoretical predictions with the results given by Cao andEvans experimentally.It should be pointed out that the model proposed is empirical and needsto be verified by more experimental results.

18.

Effects of loading condition on veryhighcycle fatigue behaviour and dominant variable analysis





LEI ZhengQiang XIE JiJia SUN ChengQi HONG YouShi《中国科学:物理学 力学 天文学(英文版)》,2014年第57卷第1期


The specimens of a high carbon chromium steel were quenched and tempered at 150°C,180°C and 300°C.Such specimens were tested via rotating bending and a pushpull type of axial loading to investigate the influences of loading condition on the behaviour of veryhighcycle fatigue(VHCF).Experimental results show the different influences of inclusion size on the fatigue life for the two loading conditions.Predominant factors and mechanism for the finegranulararea(FGA)of crack origin were discussed.In addition,a reliability analysis based on a modified TanakaMura model was carried out to evaluate the sensitivity of inclusion size,stress,and KFGA to the life of VHCF crack initiation.

19.

Empirical formula for β~decay halflives of rprocess nuclei





《中国科学:物理学 力学 天文学(英文版)》,2017年第8期


Experimental data ofβdecay halflives of nuclei with atomic number between 20 and 190 are investigated.A systematic formula has been proposed to calculateβ~decay halflives of neutronrich nuclei,with a particular consideration on shell and pair effects,the decay energy Q as well as the nucleon numbers(Z,N).Although the formula has relatively few parameters,it reproduces the experimentalβ~decay halflives of neutronrich nuclei very well.The predicted halflives for the rprocess relevant nuclei obtained with the current formula serve as reliable input in the rprocess model calculations.

20.

EXPERIMENTAL AND THEORETICAL INVESTIGATION OF THE FIRST FOLD CREATION IN THIN WALLED COLUMNS





Abbas Niknejad G.H.Liaghat H.Moslemi Naeini A.H.Behravesh《Acta Mechanica Solida Sinica》,2010年第23卷第4期


In this paper, a theoretical formula is presented to predict the instantaneous folding force of the first fold creation in square and rectangular columns under axial loading.The rectangular column is a small and single model of honeycombs with square or rectangular cells.Calculations are based on the analysis of the Basic Folding Mechanism （BFM）.For this purpose, sum of the dissipated energy rate under bending around horizontal and inclined hinge lines and the dissipated energy rate under extensional deformations was equal to the work rate of the external force on the structure.The final formula obtained in this research, reasonably predicts the instantaneous folding force of singlecell square and rectangular honeycombs instead of the average value.Finally, according to the calculated theoretical relation, the instantaneous folding force of the first fold creation in a square column was sketched versus folding distance and compared to the experimental results, which showed a good correlation.
