LAMINATION OF POLYMER FILMS BY BULK SURFACE PHOTOGRAFTING PROCESS AND PROPERTIES

A new process for lamination of polymer films by 'bulk surface photografting' has been developed. The chemical component of the invention is that the curing of reactive solution between two substrates is initiated by the surface free radicals produced by aromatic ketones and surface-hydrogen of substrates. Using the new approach, two or more polymer films are bonded together by a grafted polymer network which is grafted to adjacent substrate surfaces. The technique has been applied to film substrates of different polymers such as polyolefins, polyesters, and polyamides which have abstractable hydrogens at the surface. The photolaminated film composites containing carrier films and an intermediate functional film of low permeability give strong laminates with high barrier properties, e.g, for oxygen and air.

Two-dimensional analyses of delamination buckling of symmetrically cross-ply rectangular laminates

The conventional approach to analysis the buckling of rectangular laminates containing an embedded delamination subjected to the in-plane loading is to simplify the laminate as a beam-plate from which the predicted buckling load decreases as the length of the laminate increases. Two-dimensional analyses are employed in this paper by extending the one-dimensional model to take into consideration of the influence of the delamination width on the buckling performance of the laminates. The laminate is simply supported containing a through width delamination. A new parameterβ defined as the ratio of delamination length to delamination width is introduced with an emphasis on the influence of the delamination size. It is found that （i） when the ratio β is greater than one snap-through buckling prevails, the buckling load is determined by the delamination size and depth only; （ii） as the ratio β continues to increase, the buckling load will approach to a constant value. Solutions are verified with the well established results and are found in good agreement with the latter.

Experimental and simulation studies on delamination strength of laminated glass composites having polyvinyl butyral and ethyl vinyl acetate inter-layers of different critical thicknesses

The laminated glasses(LGs)composites are gaining popularity as protectivestructural material. Delamination strength(DS) of(LGs) with different inter-layers and their different nominal thicknesses were compared. The effect of inter-layer thickness, delamination load, and inter-layer type on DS is clearly observed from this brief study. It is concluded that inter-layer thickness has the significant role in determining the DS of LGs. The statistical analysis confirmed the strong association of DS with inter-layer thickness and the interlayer type. It was found that the LG-PVB composite has the comparatively lower DS than LG-EVA composite and inter-layer thickness has the prominent role in the determination of DS in the LG-EVAcomposite. There is an increment in DS with an increment in critical inter-layer thickness in both LG-EVA and LG-PVBcomposites. The increment in the inter-layer thickness from 0.38 mm to 0.76 mm increases DS significantly; whereas, the further increment in the inter-layer thickness to the higher value has a lesser effect. The finite element model was constituted(without considering the effect of temperature) for determining DS of LG composite. The simulation results were in a good match with experimental results. The results of the present work can be utilized by the design engineers while selecting LG for structural applications.

DELAMINATION FORMATION AND DELAMINATION PROPAGATION OF COMPOSITE LAMINATES UNDER COMPRESSIVE FATIGUE LOADING

Fatigue tests of the smooth composite laminates and the notched composite laminates under compressive cyclic loading have been carried out. The damage mechanism is discussed and analyzed. Damage evolution is monitored using stiffness decay. From these tests, it is found that the initial delamination occurs at the free boundary of smooth specimens, or the notch boundary of notched specimens, subjected to the compression-compression cyclic load. A point of view in relation to two-phases of compression fatigue delamination of composites is proposed, namely, compression-compression delamination consists of the delamination formation phase and the delamination propagation, and there is a 'damage transition point' to separate this two-phases. Furthermore, an empirical modulus degradation formula and its parameters fitting method are presented. According to the test data handling results, it is shown that this formula is univocal and can fit the test data conveniently. In addition, two kinds of new anti-buckling devices are designed for these tests. At last, the E-N curves, the D-N curves and the S-N curve of the smooth carbon fiber reinforced composite laminates of T300/648C are determined to predict the fatigue life of the notched composite laminate. And the E-N curve of the notched specimens at the given load ratio R = 10 and minimum load Pmin = -0.45 kN is also measured to verify the estimated result of fatigue life.

A Modified Cohesive Zone Model for Simulation of Delamination Behavior in Laminated Composites

Considering the promotion effect of interlaminar normal tensile stress and the inhibition effect of interlaminar normal compressive stress,two kinds of elimination initial criteria were proposed in this paper.Based on these two delamination initial criteria,a modified cohesive zone model(CZM)was established to simulate the delamination behavior in laminated composites.Numerical simulations of double cantilever beam(DCB),mixed-mode bending(MMB)and end notched flexure(ENF)tests were conducted.The results show that the proposed model can do a better job than common ones when it is used to predict laminates’delamination under interlaminar compression stress.Moreover,a factor r,named cohesive strength coefficient,was defined in this paper on account of the difference between cohesive strength and interlaminar fracture strength.With changing factor r,it shows that a moderate variation of cohesive strength will not cause significant influences on global load-displacement responses.Besides,in order to obtain a good balance between prediction accuracy and computational efficiency,there shall be two or three numerical elements within the cohesive zone.

Design and Lamination Process of Composite Fabric for Automobile

The composite fabric is a new type of automobile fabric in recent years.The three-layer composite fabric was made of different materials that were linen weaving fabric,knitting fabric and warp-knitted spacer fabric.Through testing performances of three different adhesives,the thermoplastic urethanes(TPU)hot melt powder was selected to adhere every fabric.Then,the laminating process was designed and applied.The optimized process conditions were following:the temperature was 150℃,the pressure was 2.0 N·cm-2,the time was 80 s,and the dosage of adhesive was 20 g·m-2.This new laminated fabric has multi-functions,such as comfortability,permeability and physic mechanical properties.This lamination process will be used to be the basis for the study of functional laminated car seat fabric.

Simulation of Solid Particle Interactions Including Segregated Lamination by Using MPS Method

A new MPS(Moving Particle Semi-implicit)method is developed to simulate the behaviors and interactions of multiple fine solid particles as a continuum.As fluid particles are affected by viscosity,so solid particles are affected by friction.The solid particle dynamics for landslides,dumping,and gravity sorting etc.which can be difficult to simulate using conventional MPS methods,are modeled in this paper using the developed multi-solid-particle MPS method that benefits from drawing comparisons with the corresponding fluid particle behaviors.The present MPS results for dumping solid particles are verified against the corresponding DEM(Discrete Element Method)results.The shape and angle of repose for solid particles are shown to be highly dependent on the friction coefficient between grains.The peculiar phenomenon of segregated lamination(gravity sorting)among grains of different densities has been successfully reproduced using the multi-solid-particle MPS method.Lamination quality is found to be dependent on the densities and frictional coefficients of the constituent particles.The behavior of heterogeneous mixtures of multiple solid and liquid particles are also compared and discussed.This newly developed tool offers a window into the physical dynamics of sedimentology that the broader geoscience community might benefit from.

Effect of ZrO_2 Dopant on the Sintering Behavior and Performance of MCMB-derived Carbon Laminations

Liquid ball-milling dispersant method was used to prepare the ZrO2-doped carbon laminations from mesocarbon microbeads（MCMBs）. After sintering at 1 300 ℃ in nitrogen atmosphere, the effect of ZrO2 concentration on sintering behavior, electric conductivity as well as bending strength of the carbon laminations was investigated in detail. The results showed that the volumetric shrinkage rate of the carbon laminations decreased from 38.2% to 30.9% when the ZrO2 concentration in raw materials varied from 0 to 16 wt%. Compared with undoped carbon lamination, the samples had high-electric conductivity and excellent bending strength in all cases. The electric conductivity achieved the maximum value of 225 S/cm, and the bending strength of the carbon lamination was 119.24 MPa for a concentration of 8 wt% ZrO2 in raw materials. In addition, the electric conductivity and bending strength reducing were observed when the ZrO2 concentration was higher than 8 wt%. The catalytic effect on graphitization for the carbon laminations was the most effective when the ZrO2 concentration was set at 8 wt% in raw materials.

ANNUAL LAMINATIONS IN THE SEDIMENTS OF HONGFENG LAKE, CHINA

ＡＮＮＵＡＬ ＬＡＭＩＮＡＴＩＯＮＳ ＩＮ ＴＨＥ ＳＥＤＩＭＥＮＴＳ ＯＦ ＨＯＮＧＦＥＮＧ ＬＡＫＥ， ＣＨＩＮＡＡＮＮＵＡＬＬＡＭＩＮＡＴＩＯＮＳＩＮＴＨＥＳＥＤＩＭＥＮＴＳＯＦＨＯＮＧＦＥＮＧＬＡＫＥ，ＣＨＩＮＡ￥ＷｕＦｅｎｇｃｈａｎｇ；Ｗａ...

General analytical solution to bending of composite laminated beams with delaminations

Based on the first-order shear deformable beam theory, a refined model for composite beams containing a through-the-width delamination is presented, and the deformation at the delamination front is considered. Different from the ordinary delami- nated beam theory, each of the perfectly bonded portions of the new model is constructed as two separated beams along the interface without assuming a plane section at the de- lamination front. The governing equations of the delaminated portions and bonded ones are established, combined with continuity conditions of displacements and internal forces. Solutions of delaminated composite beams with different boundary conditions, delamina- tion locations and sizes axe shown in excellent agreement with the finite element results, showing efficiency and applicability of the present model.

Delamination growth for composite laminated cylindrical shells under external pressure

The delamination growth may occur in delaminated cylindrical shells＇under external pressure. This will lead to failure of structure. By using the variational principle of moving boundary and considering the contact effect between delamination regions, in this work, the delamination growth was investigated for cylindrical shells under the action of external pressure. At the same time, according to the Griffith criterion, the formulas of energy release rate along the delamination front were obtained. In the numerical calculation, the delamination growth of axisymmetrical laminated cylindrical shells was analyzed, and the effects of delamination sizes and depths, the geometrical parameters, the material properties, and the laminate stacking sequences on delamination growth were discussed.

ENERGY RELEASE RATE COMPONENTS ANALYSIS OF LAMINATES WITH EMBEDDED DELAMINATION

This paper is the continuation of the authors' previous investigation([1]) in which the formula of total energy release rate at each point along the delamination boundary is derived by using variational method of moving boundary. In the present paper, the analytical model is reformed and the individual components of energy release rate are derived in the form of plate theory. The circular delamination embedded in circular laminates is analysed and some conclusions are obtained.

NUMERICAL ANALYSIS OF DELAMINATION GROWTH FOR STIFFENED COMPOSITE LAMINATED PLATES

A study of postbuckling and delamination propagation behavior in delaminated stiffened composite plates was presented. A methodology was proposed for simulating the multi-failure responses, such as initial and postbuckling, delamination onset and propagation, etc. A finite element analysis was conducted on the basis of the Mindlin first order shear effect theory and the von-Krmn nonlinear deformation assumption. The total energy release rate used as the criteria of delamination growth was estimated with virtual crack closure technique (VCCT). A self-adaptive grid moving technology was adopted to model the delamination growth process. Moreover, the contact effect along delamination front was also considered during the numerical simulation process. By some numerical examples, the influence of distribution and location of stiffener, configuration and size of the delamination, boundary condition and contact effect upon the delamination growth behavior of the stiffened composite plates were investigated. The method and numerical conclusion provided should be of great value to engineers dealing with composite structures.

SOLVING δ_b ON PARABOLIC LAMINATIONS

Let X be a compact set which is laminated by parabolic Riemiann surfaces. For the CR positive line bundle L, there exists an integer N ∈ N such that for any s 〉 N and any continuous v ∈∧^（0,1）X×L^×s, there exists a continuous u ∈ L^×s solving δb^-u = v.

Electrical Instability in Pentacene Transistors with Mylar and PMMA/Mylar Gate Dielectrics Transferred by Lamination Process

This study deals with electrical instability under bias stress in pentacene-based transistors with gate dielectrics deposited by a lamination process. Mylar film is laminated onto a polyethylene terephthalate (PET) substrate, on which aluminum (Al) gate is deposited, followed by evaporation of organic semiconductor and gold (Au) source/drain contacts in bottom gate top contact configuration (Device 1). In order to compare the influence of the semiconductor/dielectric interface, a second organic transistor (Device 2) which is different from the Device 1 by the deposition of an intermediate layer of polymethyl methacrylate (PMMA) onto the laminated Mylar dielectric and before evaporating pentacene layer is fabricated. The critical device parameters such as threshold voltage (VT), subthreshold slope (S), mobility (μ), onset voltage (Von) and Ion/Ioff ratio have been studied. The results showed that the recorded hysteresis depend on the pentacene morphology. Moreover, after bias stress application, the electrical parameters are highly modified for both devices according to the regimes in which the transistors are operating. In ON state regime, Device 1 showed a pronounced threshold voltage shift associated to charge trapping, while keeping the μ, Ioff current and S minimally affected. Regardless of whether Device 2 exhibited better electrical performances and stability in ON state, we observed a bias stress-induced increase of depletion current and subthreshold slope in subthreshold region, a sign of defect creation. Both devices showed onset voltage shift in opposite direction.

EXPERIMENTAL STUDY OF EFFECTS ON DELAMINATION NEAR CRACK OF ARALL BY RESIDUAL STRESS UNDER FATIGUE ＆ STATIC LOADS

The delamination near the centre crack of ARALL under fatigue and static loads is investigated, and the effects on delamination by different residual stresses are analyzed. The results show that the situations under the two kinds of loads are different.Under the fatigue load, the typical delamination with crack growth presents symmetrical hi-ellipse-shape, whereas under the condition of static tensile, the edge-effect becomes more evident. Applying a proper pre-stress to the laminate can increase the ability of anti-delamination damage.

An advanced higher-order theory for laminated composite plates with general lamination angles

This paper proposes a higher-order shear deformation theory to predict the bending response of the laminated composite and sandwich plates with general lamination configurations.The proposed theory a priori satisfies the continuity conditions of transverse shear stresses at interfaces.Moreover,the number of unknown variables is independent of the number of layers.The first derivatives of transverse displacements have been taken out from the inplane displacement fields,so that the C 0 shape functions are only required during its finite element implementation.Due to C 0 continuity requirements,the proposed model can be conveniently extended for implementation in commercial finite element codes.To verify the proposed theory,the fournode C 0 quadrilateral element is employed for the interpolation of all the displacement parameters defined at each nodal point on the composite plate.Numerical results show that following the proposed theory,simple C 0 finite elements could accurately predict the interlaminar stresses of laminated composite and sandwich plates directly from a constitutive equation,which has caused difficulty for the other global higher order theories.

Fibrous Separator with Surface Modification and Micro-Nano Fibers Lamination Enabling Fast Ion Transport for Lithium-Ion Batteries

Appropriate materials collaborated with reasonable structure can significantly increase the separator performance for lithium-ion batteries.In this work,taking the advantages of microfibrous and nanofibrous membranes and compensating for their defects,we developed a composited separator(GOPPH)with excellent overall performance by first wetting-modifying the polyethylene terephthalate microfibers and then laminating a polyvinylidene fluoride-hexafluoropropylene nanofiber layer.Such a combination not only offers the GOPPH separator,from the perspective of structure,with high porosity and hierarchical structure in terms of fiber diameter and pore size,but also provides satisfactory features including wettability,mechanical strength and thermal shutdown function that benefit from the selected materials.Meanwhile,as determined by experimental and theoretical approaches,the obtained GOPPH separator exhibits considerably enhanced lithium ion transport ability with a high lithium ion transference number and transport rate,which thereby endowing the cell with superior cycling stability with a capacity retention of 93%after 200 cycles at 1 C.Therefore,considering battery safety and performance,the GOPPH fibrous membrane could be a promising separator candidate for lithium-ion batteries.

Improving ModeⅡdelamination resistance of curved CFRP laminates by a Pre-Hole Z-pinning(PHZ)process

This paper presents an experimental investigation of the ModeⅡdelamination resistance of curved CFRP laminates reinforced with Z-pins.A Pre-Hole Z-pinning(PHZ)process is developed to reduce the in-plane damage of the Z-pinned laminates.The microstructural observation of the Z-pinned laminate specimens indicates that the PHZ process can effectively decrease the defects including the Z-pin offset angle and the area of eyelet zone.The influences of the volume fraction and diameter of Z-pin on the fracture toughness and the delamination crack growth rate of the specimens under End Notch Flexure(ENF)loading are then determined experimentally.The test results show that Z-pin increases the interlayer stiffness of the laminate.The delamination crack growth rate is reduced with the increase of Z-pin diameter and volume fraction,and a reduction up to 40%is achieved compared with the specimens without pins.Furthermore,the ModeⅡfracture toughness is significantly improved with the increase of Z-pin volume fraction.When Z-pin volume fraction increases by 1%,the achieved fracture toughness is about 200%higher compared to the unpinned laminates.

Experimental Study on Corrosion of Stainless Steel in Low Temperature Multi effect Seawater Desalination

Starting from the corrosion mechanism,this paper analyzes the characteristics of various types of stainless steel and selects the best performance composite plate composite plate stainless steel.Analyze and select the most suitable corrosion detection method based on specific practical multi working conditions,discuss the interference factors that affect metal corrosion during experimental simulation,and the advantages of newly developed sheet metal.The new development of composite board panels,with the substrate and composite materials applying their respective capabilities for MED,will bring breakthrough progress to the scientific research and engineering applica-tion of composite boards.