Interface property of dissimilar Ti-6Al-4V/AA1050 composite laminate made by non-equal channel lateral co-extrusion and heat treatment

The purpose of this paper is to examine the effect of processing parameters and subsequent heat treatments on the microstructures and bonding strengths of Ti-6Al-4V/AA1050 laminations formed via a non-equal channel lateral co-extrusion process.The microstructural evolution and growth mechanism in the diffusion layer were discussed further to optimize the bonding quality by appropriately adjusting process parameters.Scanning electron microscopes(SEM),energy dispersive spectrometer(EDS),and X-ray diffraction(XRD)were used to characterize interfacial diffusion layers.The shear test was used to determine the mechanical properties of the interfacial diffusion layer.The experimental results indicate that it is possible to co-extrusion Ti-6Al-4V/AA1050 compound profiles using non-equal channel lateral co-extrusion.Different heat treatment processes affect the thickness of the diffusion layer.When the temperature and time of heat treatment increase,the thickness of the reaction layers increases dramatically.Additionally,the shear strength of the Ti-6Al-4V/AA1050 composite interface is proportional to the diffusion layer thickness.It is observed that a medium interface thickness results in superior mechanical performance when compared to neither a greater nor a lesser interface thickness.Microstructural characterization of all heat treatments reveals that the only intermetallic compound observed in the diffusion layers is TiAl_(3).Due to the inter-diffusion of Ti and Al atoms,the TiAl_(3) layer grows primarily at AA1050/TiAl_(3) interfaces.

Vacuum-free lamination via controlled polymer adhesion for selective photogeneration and photodetection

This study attempts to develop a reproducible thin-film formation technique called vacuum-free(VF)lamination,which transfers thin films using elastomeric polymer-based laminating mediators.Precisely,by controlling the interface characteristics of the mediator based on the work of adhesion,VF lamination is successfully performed for various thicknesses(from 20 to 240 nm)of a conjugated photoactive material composed of poly[(2,6-(4,8-bis(5-(2-ethylhexyl-3-fluoro)thiophen-2-yl)-benzo[1,2-b:4,5-bʹ]dithiophene))-alt-(5,5-(1ʹ,3ʹ-di-2-thienyl-5ʹ,7ʹ-bis(2-ethylhexyl)benzo[1ʹ,2ʹ-c:4ʹ,5ʹ-cʹ]dithiophene-4,8-dione)](a polymer donor)and 2,2ʹ-((2Z,2ʹZ)-((12,13-bis(2-butyloctyl)-3,9-diundecyl-12,13-dihydro-[1,2,5]thiadiazolo[3,4-e]thieno[2ʹʹ,3ʹʹ:4ʹ,5ʹ]thieno[2ʹ,3ʹ:4,5]pyrrolo[3,2-g]thieno[2ʹ,3ʹ:4,5]thieno[3,2-b]indole-2,10-diyl)bis(methanylylidene))bis(5,6-difluoro-3-oxo-2,3-dihydro-1H-indene-2,1-diylidene))dimalononitrile(a nonfullerene acceptor).Interestingly,the organic photovoltaic and photodetecting applications,prepared by the VF lamination process,showed superior performance compared to those of devices prepared by conventional spin-coating.This is due to the overturned surface morphology,which led to enhanced charge transport ability and blocking of the externally injected charge.Thus,the reproducible VF lamination process,exploiting an adhesion-based elastomeric polymer mediator,is a promising thin-film formation technique for developing efficient next-generation organic optoelectronic materials consistent with the solution process.

Low-velocity Impact Damage Analysis of Composite Laminates Using Self-adapting Delamination Element Method

On the basis ofa 2D 4-node Mindlin shell element method, a novel self-adapting delamination finite element method is presented, which is developed to model the delamination damage of composite laminates. In the method, the sublaminate elements are generated automatically when the delamination damage occurs or extends. Thus, the complex process and state of delamination damage can be simulated practically with high efficiency for both analysis and modeling. Based on the self-adapting delamination method, linear dynamic finite element damage analysis is performed to simulate the low-velocity impact damage process of three types of mixed woven composite laminates. Taking the frictional force among sublaminations during delaminating and the transverse normal stress into account, the analytical results are consistent with those of the experimental data.

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.

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.

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.

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.

Effect of hydro co-extrusion on microstructure of duo-cast Al3003/Al4004 clad materials

The effects of hydro co-extrusion on the microstructure changes of aluminum hybrid duo-cast Al 3003/Al 4004 clad materials were studied. The specimen of duo-cast Al 3003/Al 4004 clad materials was in circle shape, and was composed of Al 3003(outside) and Al 4004(inside) materials. The specimen was extruded by the hydro co-extrusion equipment. The manufacturing conditions of the specimen were 423 K in temperature and 5 in extrusion ratio. The dimensions of the specimen were 80 mm in diameter of the Al 4004 material and 35 mm in thickness of the Al 3003 material before the hydro co-extrusion process, and 30 mm in diameter and about 5 mm in thickness after the extrusion process, respectively. The microstructure and the hardness for two specimens were investigated. The hardness value of cross section in the duo-cast Al 3003/Al 4004 clad materials before the extrusion process was increased in form of the parabola toward the center. However, after the extrusion process, it was almost constant in the portion of Al 4004 material. Lots of big voids above 1 mm in diameter in the specimen existed in the interfacing region of Al 3003 and Al 4004 materials before the extrusion process. These big voids disappeared after the process of hydro co-extrusion.

Design optimization of a slotless PM brushless motor with helical edge wound laminations for rim driven thrusters

This paper discusses the analysis and design of a very thin slotless permanent magnet （PM） brushless motor whose stator laminations are manufactured from a single strip of steel that is edge wound into a spiral （like a ＂Slinky＂） and then fitted over the windings that are preformed on the outside surface of a non-conducting former. Analytical and finite element analysis （FEA） are used to determine the con- strained optimum dimensions of a motor used to drive a rim driven thruster in which the motor rotor is fit- ted onto the rim of the propeller and the stator is encapsulated in the thin Kort nozzle of the thruster. The paper describes the fabrication of a demonstrator motor and presents experimental results to validate the theoretical calculations. Experimental motor performance results are also reported and compared with those of a slotted motor that fits within the same active radial dimensions as the slotless motor. The slotless motor, which has longer active length and endwindings, and thicker magnets than the slotted motor, was found to be less efficient and more expensive （prototype cost） than the slotted machine.

Encapsulation of Almond Essential Oil by Co-Extrusion/Gelling Using Chitosan as Wall Material

Encapsulation confers protection to substances as essential oils from processes like oxidation, evaporation or uncontrolled release. In this study almond oil capsules were obtained by co-extrusion/gelling technique. Chitosan was used as shell material and sodium triphosphate pentabasic as cross linking agent. Different encapsulation process variables were studied: cross-linker concentration, nozzles size and potential. Optical microscopy was used to determine the capsules morphology and degradability tests were performed in order to study capsules degradation over time. Results showed that nozzles size and cross linking concentration are key variables to consider in the encapsulation process. Degradability tests showed rapid weight loss.

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.

ANNUAL LAMINATIONS IN THE SEDIMENTS OF HONGFENG LAKE, CHINA

Hongfeng Lake is an eutrophic freshwater atificial reservior.It began to restore water in 1960. Three sediment cores were taken from both about 25m of water in the center of Hongfeng bake in May 1991. The stratigraphy of the three cores was easily matched .by using prominent marking horizons and characteristic aqnences of laminations. In three layer Samples studied, diatom and other algae taxa appear in repeating apuences. The presence of laminations may reflect either the regular changes of physical-chemical conditions within the lake or the variation in the intensity of erosion and transport of material from the catchment, pat iculaly where instability in the lake-water system has occult as a result of human activities. The larninations were mainly cantal by seasonal variation of envionmental conditions,particularly climate.Unlike t of the previous examples, they have ben fo￣ at most recent Sediments, in a small freshwater lake in the eastern slOPe of the QinghaiXiZang Plateau, China in a subtropical climate, which is adenly controlled by ￣theastern and southwestern mon￣n. It is believed that it's the first reported instanceOf laminated lake sediments from China.

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.

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.

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.

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.

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.

Microencapsulation of Rosemary Essential Oil by Co-Extrusion/Gelling Using Alginate as a Wall Material

An essential oil is the volatile lipophilic component extracted from plants. Microencapsulation systems protect the essential oil from degradation and evaporation, and at the same time allow a sustained release. This work analyzed and characterized the rosemary essential oil microcapsules prepared by co-extrusion technique using alginate as wall material and calcium chloride as cross linker. Several instrumental techniques were used: optical microscopy, coulter counter, Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), termogravimetric analysis (TGA), spectrophotometry, antimicrobial test and chromatography. Results show that rosemary oil has pesticidal properties, and its microencapsulation allows knowing that these properties remain inside the microcapsules.

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.