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This study presents the dynamic response analyze of a simply supported and isotropic functionally graded (FG) double curved panel under mechanical loading. The aim of the research was to investigate mechanical behavior in a FGM curved panel due to different excitation mode of dynamic loading. The novelty of this research is an investigation of von Mises equivalent stress distribution in double curved panel due to different excitation mode. Computed results are found to agree well with the results reported in the literature. Moreover, influence of volume fraction of the material is studied.

In this paper, three kinds of different fiber reinforced vinyl composite plates are prepared by VARI technique, the mechanical parameters and failure modes of these panels under different strain rates are experimentally studied. The results show that loading velocity has a great influence on the tensile modulus of elasticity and strength as well as failure mode of the plates. At the same time, UMAT functional element program is used to write the failure criterion by ABAQUS finite element software, then the damage mode of composite fiber and matrix under tensile load are studied.

In this work, the effect of the prefabricated crack offset angle on the fracture toughness of the CT specimen was studied by means of the numerical simulation of tensile fracture. It is found that offset angle has a great influence on the fracture toughness of the CT specimen with a straight crack, and the effect is obvious when the bias angle is greater than 3 degrees. For the CT specimen with an oblique crack tip, with the increase of the bias angle of the crack tip, the J-integral value and the fracture toughness are not significantly changed. At the same time, as the angle increases, the stress applied load has more obvious influence on the crack tip stress field.

For the study of the metal-rubber which is a new material used as damper component. The compression mechanical properties of metal-net rubber were studied. Through the static compression test of metal-net rubber, the influence of some factors such as: compression amount, relative density, wire diameter and bearing area. The method is variable-controlling. Experimental results show that along with the increase of the amount of compression, the nonlinear mechanical properties of metal-net rubber boosts; with the increase of relative density, the compressive capacity of metal-net rubber improves. The wire diameter influences the nonlinear mechanical properties of metal-net rubber, the larger the wire diameter, the compressive capacity is higher; the bearing area is greater, the compressive capacity and energy dissipation performance are better.

This article studies the fracture behavior of compact tension specimens under tensile loading. The test - numerical hybrid method is used to explore the effect of the location of the loading hole. And the size effect is also considered to analysis the reason of fracture behavior .The initial load for numerical simulation is based on the experimental data. In that case, the numerical simulation results can be used to study the effect of the location of the loading hole and also the size effect to the specimens.

Metal rubber material is a mesh structure woven by wire (metal rubber called MR), a new type of isolated-vibrated material with elastic rubber property [1, 2]. Static mechanical properties of MR are discussed in this paper. First of all, this paper introduces load-displacement function of micro element spring. And a constitutive model of MR is proposed. Secondly, this paper discusses how different parameters such as wire diameter and relative density influence energy dissipation. Also, compared the theoretical results with the experimental results in order to test the accuracy of the theory.

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.

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.

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.

A modified Hill yield criterion considering tension-shear stress coupling was given and material parameters of nickel-based single crystal in this criterion was determined by the Least Square Method. Crack tip plastic zones of nickel-based single crystal plate were analyzed by using this modified yield criterion and the plastic zones corresponding to mixed mode I, II crack, were derived. The crack tip plastic zones of nickel-based single crystal were compared to that of isotropic material. The influences of tension-shear stress coupling, compound ratio of mixed mode I, II crack and temperature on crack tip plastic zones were discussed. The results obtained in this paper indicate that the increasing rate of crack tip plastic zones with compound ratio in the plane stress condition is greater than that in the plane strain condition for nickel-based single crystal and the temperature has greater influence on the size of crack tip plastic zones.

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.

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.

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.

In this paper, numerical simulation on the failure process of the mixed mode crack about the concrete is carried out. The results show that the crack initiation angle and the peak load increase as the distance between the preexisting crack and the midline of the beam is greater, the distance is constant, the longer the length of the preexisting crack is, the bigger the peak load is. Due to the heterogeneity of concrete materials, the crack propagation path is tortuous, and tensile stress is the major driving force.

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.

The continuous basalt fiber (CBF) as inorganic fiber obtained from the basalt melt. It has high elastic modulus, low bulk density, low thermal conductivity, low moisture absorption rate and excellent alkali resistance, etc. In this paper, the split Hopkinson pressure bar (SHPB) technique is used for testing the CBF composite plate and its sandwich structure with aluminum foam core dynamic mechanical properties, and then to study the dynamic properties of CBF composite plate and its aluminum foam sandwich structure under different high strain rate. From the test results we can see that the CBF-foam aluminum sandwich structure has superior energy absorption properties, and also from the experiment results we can obtain that the sandwich structure dynamic stress-strain curves has a typically "three-phase" characteristics and strain rate effect.

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.

Carbon nanotubes (CNTs) are good reinforcement of composite materials, through add appropriate amount of carbon nanotubes to MoSi2 can be improve the strength and toughness of MoSi2. In this paper, the material of CNTs/MoSi2 was made through vacuum hot pressing technology. And the split hopkison press bar (SHPB) technology was used for testing the dynamic mechanical properties of CNTs/MoSi2 composite material which has different proportion of CNTs. In the SHPB experiment, in order to get better waveforms, the waveform shaping technology was used for improving the waveform quality, and also the strain gauge technology was used for testing the real strain of the specimen in the dynamic loading process. Through calculating, the dynamic stress-strain curves which under different high strain rate are given. At the same time, the strength, deformation and other test results are analyzed, and also compared them with the static compression experiment results of the CNTs/MoSi2 specimen which is tested by the electronic universal testing machine, and then obtained the dynamic performance of CNTs/MoSi2 composite material.

Application of composite laminates was very wide in aerospace engineering, civil engineering, wind energy, auto industry, etc. Low cost glass fiber textile was often applied into composite laminates by many composites companies. It is of import that investigation of mechanical properties and damage mechanism of this composites laminates. Two types of composite laminates were studied in this paper. One type of composite laminates was made of glass fiber biaxial cloth. The other was made of glass fiber composite felt. Each type composite laminates has different direction aligned. Many specimen were tested in compression with universal testing materials machine model INSTRON 5500R. Strength of composite laminates and stress-strain diagram was obtained in these experiments. Effect of fiber different orientation on compression strength of laminates was found. Shear stresses between two laminas were calculated. Fracture mechanism of composites laminates was analyzed by macro-method. Fractography of laminates was applied into analysis of mechanism. SEM photo was acquired and observed in detail. The result is that strength and failure mechanism of different types composite laminates varied with fiber orientation and different textiles.

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 paper is to present a novel inertia moment algorithm meanwhile use it to investigate the stress corrosion initiation stage of an aluminum alloy. The specimens are Al-2A12 alloy with thickness of 2mm which are immersed in the 3.5% sodium chloride solution. Three-point bending system is employed under displacement loading mode. The center displacement is 2mm, 2.5mm and 4mm, respectively. Meanwhile in order to observe the stress corrosion process, the solution temperature increases from 20.9 to 61.3 degrees centigrade. Average intensity method is recommended to contrast due to its validity for corrosion analysis. The results show at room temperature, the material is not prone to stress corrosion. General electrochemical corrosion is a major role and the process is comparatively moderate. Stress corrosion appears when the temperature has increased. It is a phenomenon of localized corrosion and exhibits asymmetric property. Accompanied with the corrosion process developed, this kind of asymmetric property is increasingly apparent from three-dimensional results.

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.