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It’s very important to select appropriate dimensions for manufacture of honeycomb sandwich. In this paper, the experimental and theoretical methods were compared. The results are proved that the theoretical formula can be applied to engineering design. The impact factor of staties mechanical properties of honeycomb panels also was studied. And a theoretical basis for the design of honeycomb sandwich panels is provided.

This article study the dynamic fracture behavior of compact tension specimens under tensile wave loading[1-3]. And the test - numerical hybrid method is used to satisfy the condition of dynamic stress equilibrium. The initial load for numerical simulation is based on the experimental data. In that case, the numerical simulation results can be used to analysis the dynamic stress equilibrium.

Compared with the traditional metal square cabin, the new type square cabin makes a good performance on lightweight and can also improve the stiffness of the structure. Both the static and dynamic analysis results which tested under the condition of general standard show that: the new type cabin which made by aluminum foam sandwich composite panels can reach the purpose of light weight design and also can improve the stiffness of the structure. What is more, optimum design is used on the dimension parameter to enhance the property of the square cabin.

The paper mainly concerns about how relative density and pre-compression quantity of metal rubber shock absorber (MRSA) affect acceleration transmissibility, natural frequency and other parameters of MRSA. In order to study the influence law, sine wave sweep experiment was conducted on different MRSA, and the final data was processed. The influence law could provide reference for practical application of MRSA.

This paper briefly describes the preparation process of SPS composite plate. The compress, buckling and three-point bending tests of SPS composite steel plates are studied. Each test gives the failure mode and stress-strain curve. The results may provide a reference for further research and engineering applications of SPS composite plate.

The mooring system initial design is quasi-static method based on catenary method. The mooring line stiffness derivation also base on catenary method. In the paper, using jumping wire of high voltage cable calculation method, design the mooring system. Building initial design model, considering the mooring line stiffness and drift angle of mooring line and structure.

In 3-point bending fatigue experiments of sandwich plate with visoelastic core and steel faceplates, it is found that response loading of specimen is very sensitive to cycling frequency. From fatigue test, different loading response of sandwich beam obtained in various cycling frequencies. Based on viscoelastic theory, responses of deformation of sandwich plate in cyclic square load wave are calculated. And an explanation of influences of cycling frequency is elaborated.

Some fundamental issues, such as stress wave dispersion effect, loss of contact, pulse shaping effect are still needed to thoroughly understand in Hopkinson pressure bar loaded fracture experimental techniques. In order to avoid the influence of stress wave dispersion on the analysis of dynamic experimental results, a computational procedure has been developed based on the combined analytical solution of Pochhammer-Chree with Fourier spectroscopy analysis. The validity of this proposed computational procedure was confirmed via the comparison with the experimental stress pulses obtained from pulse-shaped tests. The experimental results can be easily interpreted and the testing accuracy can be improved using this computational procedure.

The effect of the interface slip is neglected in most studies on calculating deflection of sandwich beams. By taking a simply supported sandwich beams under uniformly distributed loads as an example, simplified analytical models of the interface slip are established, and corresponding clculation formulas of interface slip between steel panels and concrete and section curvatures are derived. The formula for deflection of sandwich beams are then presented. This formula reflects the relationship of influence each other between the interface slip and deflection.

Sandwich plate system (SPS) with polyurethane elastomer is more and more used on ship buildings as grillage. A Comparative Study on critical buckling loads between steel grillage and SPS stiffening plate are carried out in this paper. Plate elements and beam elements are used in numerical simulation and a rectangular model is taken as a calculating example. By using of FEA software ANSYS, ultimate buckling loads are calculated with different influential factors between steel grillage and SPS stiffening plate, including the number of stiffening ribs, inertia moment of stiffening ribs, and the thickness of plates. the analysis results of comparison shows that SPS stiffening plates have better performance than steel grillage under in plane compressive loadings.

In this study, based on Goodman stress correction algorithm, four point bending fatigue behavior of brazed steel honeycomb sandwich panels at room temperature is simulated using Fe-safe emulation module. The cyclic load was sinusoidal with a frequency f= 10 Hz. The residual life and security coefficient are given in the condition of design fatigue lifetime of 106 cycles. The results show that, in the local deformation, local maximum deformation occurs in the core wall under the load region, indicate that this region is the failure region of fatigue. And the residual life of the core wall in this region is less because of local stress concentration, the probability of failure becomes high, while the residual life in the region far away from the mid-span is high.

In this paper, flatwise tensile test (FWT) and modified double cantilever beam (DCB) experiment were conducted to investigated the debond fracture of sandwich plate with corrugated core. In the experiment, the crack always stays at the face/core interfacial. Tensile bond strength of face core can be given from the flatwise tensile test and we can get the mode I fracture toughness GIC from DCB tests. It is found that the trends of curves change greatly at the beginning, with the propagation of crack, load against open displacement curves change smoothly. In order to simulate the face/core failure of sandwich plate with corrugated core, the cohesive element model is used. Tensile strength and strain energy release rate measured by the experiments presented in this paper are used in as parameters for simulation of the debond fracture. By comparing with the experiment results, the model can express the face/core failure of sandwich plate with corrugated core validly.

When the front end of the supercavitating vehicles subjects to very large axial non-stationary random excitation at high speed motion under water, it is necessary to analyze dynamic responses of supercavitating vehicles under non-stationary random excitation. The dynamical equation of supercavitating vehicles is transformed into the form of state equations. The Simpson integration method is going to calculate the integral term of the general solution of state equation to improve the precise integration method. The explicit expression of dynamic responses of supercavitating vehicles is deduced, the means and variances of structural responses are calculated with operation laws of the first moment and second moment. Under different sailing speeds and different cone-cavitator angles dynamic responses of supercavitating vehicles are given by the examples, and the effectiveness of the method was demonstrated.

Based on Reissner’s sandwich plate theory, the critical globlal buckling equation of sandwich plate with ribs is deduced by energy method under simple support boundary conditions. And the critical buckling solution is obtained and discussed here. Afterwards a rectangular sandwich plate with steel faceplate and polyurthane core is taken as an example. The influence on critical global buckling stress with different inertia moments in rectangular sandwich plates are discussed. simularly the effect of the lengh ratio of two sides and the thickness of rectangular sandwich plate are also studied.

The aim of this work is to investigate the fatigue behaviors of the steel honeycomb sandwich beams at 400°C through three point bending experiments. A stiffness reduction approach was adopted which was further based on the interpolation by the empirical functions of experimental results. For load control fatigue experiments, the evolution relations between number of cycles and displacement were obtained through real-time deformation monitoring of the specimens. A method based on exponential function fit was adopted in the further analysis, whose coefficients depended on the material properties, loading levels and high temperature conditions. This approach allowed us to predict the high temperature fatigue life of specimens while avoiding a large number of experiments. The results showed that experimental and prediction results were in a good agreement.

On the basis of analyzing the special requirements for security for the high-level radioactive waste storage structure, the seismic design parameters of this engineering are determined. There is no criterion that determines the design ground motion parameters of underground engineering. Based on the thought of the severest design ground motion, the basic methods and principles to determine the design ground motion parameters of underground structure are put forward. The characteristics of high-level radioactive waste storage structure are analyzed, and the frequencies corresponding to the maxim modal participation factors are gain. Combined with the analysis of the site geological safety assessment report, through the initial search and optimization with the method of numerical simulation, the design ground motion parameters of the high-level radioactive waste storage structure on the specific site is determined. The method is easy to operate, which can also be applied in other important deep underground engineerings.

In this paper, the sandwich structure which is consist by the aluminum foam core and CBF(continuous basalt fiber) composite plate is tested by the static and dynamic mechanical property under confining pressure, and the confining pressure experiment is done through add cylindrical tube to the sandwich structure circular specimens. The static mechanical property is tested by WDW3100 electronic universal testing machine, and its dynamic mechanical property is tested by the SHPB(Spilt Hopkinson Press Bar) device, Besides, the strain rate effect of this sandwich structure under confining pressure is tested too, From the experiment results we can see the static and dynamic mechanical properties of confining and no confining results is very different, and this study will provide references for further numerical simulation and damage studying of this kind of sandwich structure.

The CBF (continuous basalt fiber) composite as new and high mechanical property material have been widely applied in actual engineering. The composite material may inevitably occur all kinds of defects during fabrication and using, so in this paper, the AE (acoustic emission) and ESSPI (electronic shearography speckle pattern interferometry) technique are adopt to study the defects or damage of the CBF composite plate. The AE technique is adopted to detect the damage phenomenon of the CBF composit plate specimen tension experiment, and the ESSPI technique is adopt to study the defects of the CBF composite plate which its defects are made by artificial. From the experiment results it can be see that these techniques can detect the position and damage of the CBF composite plate, and these study can provide useful reference for the application of the CBF composite.

A split tensile test methodology has been established for the concrete spheriform specimens with the principal stress ratio of σ1:σ2:σ3=0.24:0.24:-1 in order to study the tensile-tensile-compressive tri-axial strength. Using a Universal Material Testing Machine and Split Hopkinson Pressure Bar, the quasi-static and dynamic spliting tensile tests have been conducted for the concrete spheriform specimens consisting of 1% steel fiber. In the quasi-static test, the average strain rate of the steel fiber reinforced concrete specimens was 8.3×10-5s-1and the split tensile strength was found to be 0.77MPa, which is consistent with the existing literature. In the high strain rate tests, the average strain rate was 170s-1and the split tensile strength was found to be 1.01MPa. When compared with the quasi-static testing results, it is seen that the split tensile strength of the steel fiber reinforced concrete increases with increasing strain rate. The split tensile test methodology established in the present paper is simple and inexpensive, while the strength obtained located on the meridian plane of tension and compression, has practical significance.

A method of fatigue damage analysis for sandwich panels on ship is studied in this paper. When ship is navigating on the sea, the waves that ship encounters can be regarded as a stochastic process. And responses of ship movement can also be regarded as a series of stochastic spectrums. By using of finite element method, loads spectrums of inner ship structures in different sea conditions can be obtained. Then short term or long term distribution of stress range can be determined. Residual stiffness modal is used to describe the damage of sandwich panels under fatigue loads. And fatigue damage variable D is defined based on stiffness degration. An integral equation to calculate fatigue damage under loads spectrum is constructed to describe the damage of ship sandwich structure in long term and short term stress spectrum distributions.

Light weight aluminum alloy honeycomb materials are ideal lightweight structure materials, which have higher specific strength and stiffness, and widely applied in aviation, aerospace, automobile and so on, and also it is an ideal material for damping, buffering, heat insulation and energy absorption. In this paper, the SHPB technique which the aluminum alloy bar diameter is 37mm is used for studying the dynamic mechanics property of the lightweight aluminum alloy honeycomb materials which the diameter is 30mm, and then to study the dynamic mechanical properties of the material, from the results we can see dynamic strain-stress curves can be divided into three phases, elastic phase, stress platform and compaction phase. And the numerical simulation method was used for study the dynamic deformation process of the honeycomb panel material under impact load, and also compare the results with the specimen cell figures which were observed by the microscope.

In this research, some concrete three-point bending specimens (beams) reinforced by FRP are used in numerical simulation to study the influence of the reinforcement on fracture mechanism and the extreme load-bearing capacity of the specimens. The numerical simulation results show the propagation of the crack in concrete is controlled by using FRP. Meanwhile the load-bearing capacity is increased greatly and failure modes are changed.

Honeycomb sandwich structures are generally designed to carry flexural loads. However, mechanical properties can be influenced by accidental impacts, or service conditions. Thus a nondestructive detection testing is desired for them. In contrast to many conventional nondestructive evaluation (NDE) techniques, acoustic emission (AE) technique permits continuous damage inspection, classification and identification of failure modes in real time. In this work the fracture process of steel honeycomb sandwich beams has been investigated by in-situ AE technique. Pre-cracks were made both for L-direction and W-direction specimens subjected to three-points bending loads. Damage initiation sites were observed in the vicinity of the crack tip. A series of curves among the AE hits, AE amplitude, AE energy and loading time were obtained. Damage characteristics were discussed based on the above parameters. The results indicate AE characteristic parameters can reflect the damage and failure process of specimens. A good agreement was found between the experimental and analytical results.

The elastoplastic instability of the symmetrical double-arc ring-stiffened cylindrical shell was analyzed. The critical pressure was obtained for small deflection elastoplastic buckling of the cylindrical shell under hydrostatic pressure. The critical pressure for large deflection buckling of the cylindrical shell with initial geometric imperfections was determined under hydrostatic pressure by using nonlinear large deformation theory. The effects of hoop equivalent wave number, initial geometric imperfection and the central angle of circular arc on buckling mode and critical pressure of double-arc ring-stiffened cylindrical shell were analyzed. The results showed that the hoop equivalent wave number of arc cylindrical shell had an main effect on the critical pressure of the structure, designed equivalent hoop wave number of double-arc cylindrical shell should not be approach to the hoop wave number corresponding to minimum critical pressure, and the central angle of circular arc had less effect on critical pressure of the structure.

The stress criterion of multiaxial high cycle fatigue is a type of non-linear equation of high-order. It is used to predict the failure of fatigue in proportional torsion and bending loads. Soon-Bok Lee presented a new design criterion for fully reversed out-of phase torsion and bending. The values are randomized in different random distributions in Lee’s criterion formula. The correlations among random variables are considered and limit state equation is also established. This paper attempts to use First Order Reliability Method (FORM) and Second Order Reliability Method (SORM) to calculate the reliability of material fatigue in torsion and bending loads. The example is calculated and it is found that the failure probability estimated by using the SORM is more reliable than those of the FORM in multiaxial high cycle fatigue.

Shape memory alloy is a good candidate for realizing the passive control of structural vibration due to its excellent characteristic of energy dissipation. In this paper, the damping characteristic of shape memory alloy is quantitatively described based on Liang’s phase transformation model and thermo-mechanical constitutive equation for shape memory alloy. The vibration performances of a beam structure with shape memory alloy damper are investigated based on basic knowledge of vibration theorem. Numerical calculations show that the vibration of beam structure is well reduced by using the shape memory alloy damper.

Sacttering of SH-wave of combined deffectiveness which included single circular cavity and double linear cracks in elastic medium was investigated in detail. Analytic solution of this problem was obtained by Green’s Function method and idea of crack-division at actual position of crack at two times. There were two key steps of this method. First step was to employ a special Green’s Function which was a fundamental solution of displacement field for an elastic space with a cavity in it subjected to out-of-plane harmonic line source force at any point at first. The sceond step was crack-division which was artificially to produce a crack by apllying opposite shear stress caused by incident SH-wave. Distribution of dynamic stress concentration factor (DSCF) at edge of cavity was studied by numerical analysis. Distribution Curves of DSCF of three models were plotted by numerical method in polar coordinate system. Three models were one circular cavity and without crack, one circular cavity and single crack and single circular cavity double cracks. The results were compared and discussed in different incident angle of SH-wave.Conclusion was that the interaction among SH-wave, single cavity and double crack was obvious. Dynamic stress concentration factor varied with angle and distance between cavity and crack.

A complete analysis was made for an isotropic hardening rate-type elastoplastic constitutive model with the logarithmic stress rate utilizing solid shafts torsion test in the large strain range. The deformation rate, the logarithmic spin, the Kirchhoff stress and the logarithmic stress rate of the Kirchhoff stress were obtained for the free-end solid shaft torsion test when considering Swift effect. Utilizing the results obtained from the solid shaft torsion test, the plastic rigidity function in the isotropic hardening elastoplastic constitutive model was determined at finite strain range. It was shown that the influence of Swift effect on finite strain constitutive model was related to the varying rate of axial deformation and the varying rate of radius deformation to shear strain, and the plastic rigidity function corresponding to the logarithmic stress rate was the same as that corresponding to the Jaumann stress rate when neglecting Swift effect. Solid shaft can achieve very large strain without buckling in torsion test. They can be used to accurately determine the large strain elastoplastic behavior [1-3]. Many researchers are interesting in the theoretical study and experimental study on large strain torsion deformation [1-7]. Jaumann objective stress rate is often adopted for study on constitutive models [1], but Nagtegaa J C [8] discovered that Jaumann stress rate may render oscillatory stress response for anisotropic kinematics hardening simple shear problem. After that, great interests focus on the issues of choosing an appropriate objective stress rate in rate type constitutive models. The expression of logarithmic stress rate with logarithmic spin can be found in Xiao H [9]. It had been proved that among all rate type elastoplastic constitutive models, only those with the newly discovered logarithmic stress rate fulfill the self-consistency criterion. In this paper, the parameter in large strain isotropic hardening elastoplastic constitutive model is determined with logarithmic rate of Kirchhoff stress utilizing solid shaft torsion test.

Concrete is a type of engineering composites which is widely used in military and civil structures. The static performance of concrete can not be used to estimate the variation of concrete under high strain rates under dynamic loads. By introducing the three point bending test under static and dynamic loads, the plane strain fracture toughness KIC and KId were measured. Using the application of experimental-numerical method a three-dimensional model has been established by FEM software Ansys/LS-DYNA, to carryout transient analysis, and the response curves of stress intensity factor-time through the opening displacement of fracture. Thus, with obtaining the cracking time by the method of strain-gauge, the dynamic plane strain fracture toughness KId can be determined. By comparing KIc and KId we could conclude the result which meant concrete was more liable to crack under dynamic load.

A shape memory alloy (SMA) torsion actuator is designed by using SMA wires and a thin-walled tube. A mechanical model, which predicts the thermo-mechanical behaviors of the SMA torsion actuator, is developed based on the knowledge of solid mechanics and constitutive relation of SMA. The relationship of the torsion-angle and temperature of the SMA torsion actuator is numerically described by using the mechanical model coupled with Tanaka’s, Liang’s and Zhou’s phase transformation models of SMA respectively. Results show the mechanical model well predict the thermo-mechanical behaviors of the SMA torsion actuator.

In this paper, RFPA－dynamic numerical simulation system was adopted to simulate the entire process of the three–point bending specimen with off–center edge-crack propagation to the specimen macroscopic crack which under the dynamic load function. And showed the whole process of the cement mortar specimen crack propagation which under the dynamic load function, as well as the whole field stress distribution picture, and has carried on analysis the specimen destruction process, has pointed out the influence of the no dimension quantity a/L change to crack expansion path and the destruction form.

The aim of this work is to investigate static and thermal-mechanical strength and fatigue behaviors of steel honeycomb sandwich beams through three-point bending. The bending strength limits at different experimental temperatures (room temperature, 200, 300 and 400°C, respectively) are obtained. The bending fatigue behaviors at high temperature are discussed and the fatigue test results are presented in standard S/N diagrams. Meanwhile damage and failure modes are reported and analyzed. Effects of the honeycomb cell orientation (L or W) on the maximum load and on the damage processes are also investigated.

The aim of this work is to investigate the initiation stage of corrosion process of an aluminum alloy by dynamical speckle method. The test specimens are Al-2A12 alloy with thickness of 2mm which are immersed in the 3.5%, 1.3% sodium chloride solution and pure water. Three-point bending tests are employed and center displacement of the specimen is 2.5mm. The real-time speckle monitoring technique has been employed and the optical measuring system is built to observe the corrosion process in local region by means of measuring the local surface speckle activity of the specimens. A novel algorithm named improved inertia moment (IIM) is presented to predict the corrosion initiation tendency. Meanwhile average intensity method is recommended to contrast with IIM due to its validity in characterizing the corrosion initiation process of aluminum alloy. The results show the trends representing the corrosion initiation, calculated by two different methods are almost the same. Moreover the presented arithmetic can simplify the heavy numerical calculation task and has relatively higher efficiency than inertia moment method. The full-field information of the investigated local region which denoted the corrosion situation is demonstrated in form of three-dimensional image. The results are according with the actual situation. Thus the presented arithmetic is feasible and effective.

The aim of this work is to use non-destructive optical measurement techniques for defect detection. This paper presents the application of electronic shearography speckle pattern interferometry (ESSPI) to detect visible and invisible on the surface defects of a pine wood specimen The different artificial defects were created under the pine wood surface to simulate "defected" samples. The ESSPI set-up based on a He-Ne CW laser has been developed and used for studying the possible locations, sizes and shapes of wood defects. The results were real time and well agreed with the actual defects. Therefore the present method is feasible.

Honeycomb sandwich structures are significant to be used as applied to thermal protection system on reusable launch vehicle. In this paper the fatigue and impact properties of a novel metallic thermal protection material have been investigated and predicted at room temperature. A series of strength tests are carried out to obtain parameters firstly for further experiments. A set of tension-tension stress fatigue tests and impact tests based on split-Hopkinson pressure bar are carried out. Different high strain rate impact experiments are accomplished. The curves of dynamical stress, strain and strain rate are obtained. Also the cell units images after impact are presented. The results show the fatigue properties of honeycomb sandwich panels are comparatively better. And it has the advantages of anti-impact resistance and high, energy absorption capability.

A Co-based superalloy honeycomb thermal protection system (TPS) panel has been fabricated. A series of strength tests such as the lateral tensile strength and flatwise compressive properties were carried out at room temperature. The tensile ultimate strength is higher than 59MPa, the flatwise compressive strength is higher than 15MPa. Two optical non-contact methods are introduced in this work. Longitudinal strains of a lateral tensile specimen were obtained using digital speckle correlation method. The equivalent elastic modulus was calculated further. Debonding defects between honeycomb core and face sheets were detected by ESSPI. The size and approximate location were decided real-time. The results show these two methods are feasible.

Mechanical tests of a Co-based superalloy honeycomb thermal protection system (TPS) panel are finished at room temperature. The lateral tensile limit strength is higher than 59MPa and nearly four multiples of the flatwise compressive strength. Also the modulus in lateral tests are nearly two multiples of the ones under compressive loads. Because of many advantages in application, two optical non-contact methods are introduced in this work to solve different problems of honeycomb sandwich panels. Longitudinal strain of lateral tensile specimens is obtained by digital speckle correlation method (DSCM) and the results of different sub-pixel methods are constrasted. Then the equivalent elastic modulus is calculated further. Electronic speckle shearography pattern interferometry (ESSPI) is presented to obtain the nondestructive results of debonding defects between honeycomb cores and face sheets. Also the size and approximate location are decided real-time. All the results show the two introduced methods are feasible.