Post-collisional magmatism contains important clues for understanding the reworking and growth of continental crust,as well as lithospheric delamination and orogenic collapse.Early Devonian magmatism has been identifi...Post-collisional magmatism contains important clues for understanding the reworking and growth of continental crust,as well as lithospheric delamination and orogenic collapse.Early Devonian magmatism has been identified in the North Qilian Orogenic Belt(NQOB).This paper reports an integrated study of petrology,whole-rock geochemistry,Sm-Nd isotope and zircon U-Pb dating,as well as Lu-Hf isotopic data,for two Early Devonian intrusive plutons.The Yongchang and Chijin granites yield zircon U-Pb ages of 394-407 Ma and 414 Ma,respectively.Both of them are characterized by weakly peraluminous to metaluminous without typical aluminium-rich minerals,LREE-enriched patterns with negative Eu anomalies and a negative correlation between P_(2)O_(5) and SiO_(2) contents,consistent with geochemical features of I-type granitoids.Zircons from the studied granites display negative to weak positive ε_(Hf)(t)values(−5.7 to 2.1),which agree well with those of negative ε_(Nd)(t)values(−6.4 to−2.9)for the whole-rock samples,indicating that they were derived from the partial melting of Mesoproterozoic crust.Furthermore,low Sr/Y ratios(1.13-21.28)and high zircon saturation temperatures(745℃ to 839℃,with the majority being>800℃)demonstrated a relatively shallow depth level below the garnet stability field and an additional heat source.Taken together,the Early Devonian granitic magmatism could have been produced by the partial melting of ancient crustal materials heated by mantle-derived magmas at high-temperature and low-pressure conditions during postcollisional extensional collapse.The data obtained in this study,when viewed in conjunction with previous studies,provides more information about the tectonic processes that followed the closure of the North Qilian Ocean.The tectonic transition from continental collision to post-collisional delamination could be constrained to~430 Ma,which is provided by the sudden decrease of Sr/Y and La/Yb ratios and an increase in zircon ε_(Hf)(t)values for granitoids.A two-stage tectonic evolution model from continental collision to post-collisional extensional collapse for the NQOB includes(a)continental collision and crustal thickening during ca.455-430 Ma,characterized by granulite-facies metamorphism and widespread low-Mg adakitic magmatism;(b)post-collisional delamination of thickened continental crust and extensional collapse of orogen during ca.430-390 Ma,provided by coeval high-Mg adakitic magmatism,A-type granites and I-type granitoids with low Sr-Y ratios.展开更多
The use of terahertz time-domain spectroscopy(THz-TDS)for the nondestructive testing and evaluation(NDT&E)of materials and structural systems has attracted significant attention over the past two decades due to it...The use of terahertz time-domain spectroscopy(THz-TDS)for the nondestructive testing and evaluation(NDT&E)of materials and structural systems has attracted significant attention over the past two decades due to its superior spatial resolution and capabilities of detecting and characterizing defects and structural damage in non-conducting materials.In this study,the THz-TDS system is used to detect,localize and evaluate hidden multi-delamination defects(i.e.,a three-level multi-delamination system)in multilayered GFRP composite laminates.To obtain accurate results,a wavelet shrinkage de-noising algorithm is used to remove the noise from the measured time-of-flight(TOF)signals.The thickness and location of each delamination defect in the z-direction(i.e.,through-the-thickness direction)are calculated from the de-noised TOF signals considering the interaction between the pulsed THz waves and the different interfaces in the GFRP composite laminates.A comparison between the actual and the measured thickness values of the delamination defects before and after the wavelet shrinkage denoising process indicates that the latter provides better results with less than 3.712%relative error,while the relative error of the non-de-noised signals reaches 16.388%.Also,the power and absorbance levels of the THz waves at every interface with different refractive indices in the GFRP composite laminates are evaluated based on analytical and experimental approaches.The present study provides an adequate theoretical analysis that could help NDT&E specialists to estimate the maximum thickness of GFRP composite materials and/or structures with different interfaces that can be evaluated by the THz-TDS.Also,the accuracy of the obtained results highlights the capabilities of the THz-TDS for the NDT&E of multilayered GFRP composite laminates.展开更多
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...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 P min =-0.45kN is also measured to verify the estimated result of fatigue life.展开更多
Cu/Al bar clad material was fabricated by a drawing process and a subsequent heat treatment.During these processes,intermetallic compounds have been formed at the interface of Cu/Al and have affected its bonding prope...Cu/Al bar clad material was fabricated by a drawing process and a subsequent heat treatment.During these processes,intermetallic compounds have been formed at the interface of Cu/Al and have affected its bonding property.Microstructures of Cu/Al interfaces were observed by OM,SEM and EDX Analyser in order to investigate the bonding properties of the material.According to the microstructure a series of diffusion layers were observed at the interface and the thicknesses of diffusion layers have increased with aging time as a result of the diffusion bonding.The interfaces were composed of 3-ply diffusion layers and their compositions were changed with aging time at 400 °C.These compositional compounds were revealed to be η2,(θ+η2),(α+θ) intermetallic phases.It is evident from V-notch impact tests that the growth of the brittle diffusion layers with the increasing aging time directly influenced delamination distance between the Cu sleeve and the Al core.It is suggested that the proper holding time at 400 °C for aging as post heat treatment of a drawn Cu/Al bar clad material would be within 1 h.展开更多
By employing the two-dimensional analysis, i.e.,plane strain and plane stress, a semi-analytical method is developed to investigate the interfacial delamination in electrodes. The key parameters are obtained from the ...By employing the two-dimensional analysis, i.e.,plane strain and plane stress, a semi-analytical method is developed to investigate the interfacial delamination in electrodes. The key parameters are obtained from the governing equations, and their effects on the evolution of the delamination are evaluated. The impact of constraint perpendicular to the plane is also investigated by comparing the plane strain and plane stress. It is found that the delamination in the plane strain condition occurs easier, indicating that the constraint is harmful to maintain the structure stability. According to the obtained governing equations, a formula of the dimensionless critical size for delamination is provided, which is a function of the maximum volumetric strain and the Poisson's ratio of the active layer.展开更多
In this paper, the problem of axisymmetric buckling and postbuckling of a circular thin-film delamination bridged by through-thickness fiber tows in 3D composites is presented. An iterativeprocedure based on Taylor’s...In this paper, the problem of axisymmetric buckling and postbuckling of a circular thin-film delamination bridged by through-thickness fiber tows in 3D composites is presented. An iterativeprocedure based on Taylor’s series expansion is used to generate a family of nondimensionalized post-buckling solutions of the above problem by yon Karman’s nonlinear plate theory. Attention is fo-cused, herein, on the effects of the bridge force of through-thickness fibers on the buckling and post-buckling behavior of the delamination. It is found that fiber bridge not only increases the ability of re-sisting delamination buckling and postbuckling, but also brings on the jump of the delamination deflec-tion mode during the postbuckling phase. Consequently the behavior of the composite structure with de-lamination is greatly improved, such as increasing the residual strength and prolonging the service life.展开更多
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 ef...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.展开更多
The East Asia continent is characterized by a mosaic architecture with various composing blocks,such as the North and South China blocks,which had been collaged in Late Permian to Triassic in response to the break-up ...The East Asia continent is characterized by a mosaic architecture with various composing blocks,such as the North and South China blocks,which had been collaged in Late Permian to Triassic in response to the break-up of Pangea.In the Late Mesozoic.展开更多
A new solvothermal post-synthesis treatment for preparing high aspect ratio magnesium aluminium layered double hydroxides(Mg Al–LDHs) has been developed. Treating laurate-intercalated Mg Al–LDHs in pure ethanol in a...A new solvothermal post-synthesis treatment for preparing high aspect ratio magnesium aluminium layered double hydroxides(Mg Al–LDHs) has been developed. Treating laurate-intercalated Mg Al–LDHs in pure ethanol in an autoclave for 48 h at 150 °C was found to produce delaminated MgA l–LDH nanosheets with a thickness of ~2.6 nm and an aspect ratio of ~105. It is proposed that the high pressure solvothermal process promotes the insertion of ethanol molecules into the LDH interlayer space, thereby facilitating delamination. This new post-synthesis treatment provides the opportunity for a facile, large scale route to highly delaminated high aspect ratio LDHs, which might be of interest towards novel nanomaterials for energy conversion and storage.展开更多
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...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.展开更多
For the application of second generation high temperature superconducting coated conductors (CCs) with layered structures, thermal mismatch between different components and electromagnetic force exerted in superconduc...For the application of second generation high temperature superconducting coated conductors (CCs) with layered structures, thermal mismatch between different components and electromagnetic force exerted in superconducting layer in a working magnet can cause transverse tensile stress, which would result in delamination behavior. Therefore many research groups have designed experiments to measure the delamination strength and dedicate to improving that. However, the reason of the discrete distribution of measured data has still not get quantitatively studied, besides, there are lack of investigations on the method of changing depositing conditions to improve the delamination strength except by adding an additional metal layer. In this work, we adopt an anvil test device and obtain delamination strengths as 29.6 MPa of YBa2Cu3O7-x (YBCO)/buffer and 114.6 MPa of buffer/substrate by combing energy disperse spectroscopy (EDS) detection. The reason of discretized measurement data on the delamination strength is explained. Moreover, we find that different temperatures during Ag deposition determine the bonding force of Ag and YBCO layer. The Delamination strength between Ag and YBCO layer increases from 4.4 MPa to larger than 114.6 MPa with temperature elevated from 30℃ to 100℃. Hence we present a novel method for improving the delamination strength of YBCO CCs by setting an optimal temperature of Ag deposition.展开更多
A fracture mechanics analysis is conducted for a delamination problem of a multilayered thermoelectric material(TEM) that consists of an n-type layer and a p-type layer sandwiched by an insulating layer. A time-varyin...A fracture mechanics analysis is conducted for a delamination problem of a multilayered thermoelectric material(TEM) that consists of an n-type layer and a p-type layer sandwiched by an insulating layer. A time-varying energy release rate is presented when the n-type layer delaminates from the insulating layer. Effects of the temperature difference across the system and the applied electric current on the energy release rate are identified. The influence of the thickness ratio of the insulating layer to the thermoelectric(TE) layer is also examined. Based on the energy release rate criterion,the critical temperature difference for delamination propagation is obtained. Some useful conclusions are given.展开更多
Exit delamination is excessive drilling thrust force.Therefore,it is necessary to investigate the critical thrust force which cause exit delamination when carbon fibre reinforced plastics(CRFP)is drilled.According to ...Exit delamination is excessive drilling thrust force.Therefore,it is necessary to investigate the critical thrust force which cause exit delamination when carbon fibre reinforced plastics(CRFP)is drilled.According to the linear elastic fracture mechanics,the mechanics of composite material and the classical thin plate bending theory,a common theoretical model of the critical drilling thrust force for CFRP plates is established.Compared with the experimental data of previous studies,the results show that the theoretical values agree well with the experimental values.This model can be used to forecast the critical thrust force for the drilling-induced delamination of CFRP.展开更多
The A-type granites with highly positiveε_(Nd)(t)values in the West Junggar,Central Asian Orogenic Belt(CAOB),have long been perceived as a group formed under the same tectonic and geodynamic setting,magmatic sourceq...The A-type granites with highly positiveε_(Nd)(t)values in the West Junggar,Central Asian Orogenic Belt(CAOB),have long been perceived as a group formed under the same tectonic and geodynamic setting,magmatic sourceq and petrogenetic model.Geological evidence shows that these granites occurred at two different tectonic units related to the southeastern subduction of Junggar oceanic plate:the Hongshan and Karamay granites emplaced in the southeast of West Junggar in the Baogutu continental arc;whereas the Akebasitao and Miaoergou granites formed in the accretionary prism.Here the authors present new bulk-rock geochemistry and Sr-Nd isotopes,zircon U-Pb ages and Hf-O isotopes data on these granites.The granites in the Baogutu continental arc and accretionary prism contain similar zirconε_(Hf)(t)values(+10.9 to+16.2)and bulk-rock geochemical characteristics(high SiO_(2)and K_(2)O contents,enriched LILEs(except Sr),depleted Sr,Ta and Ti,and negative anomalies in Ce and Eu).The Hongshan and Karamay granites in the Baogutu continental arc have older zircon U-Pb ages(315-305 Ma)and moderate^(18)O enrichments(δ^(18)_(O_(zircon))=+6.41‰-+7.96‰);whereas the Akebasitao and Miaoergou granites in the accretionary prism have younger zircon U-Pb ages(305-301 Ma)with higher^(18)O enrichments(δ^(18)_(O_(zircon))=+8.72‰-+9.89‰).The authors deduce that the elevated^(18)O enrichments of the Akebasitao and Miaoergou granites were probably inherited from low-temperature altered oceanic crusts.The Akebasitao and Miaoergou granites were originated from partial melting of low-temperature altered oceanic crusts with juvenile oceanic sediments below the accretionary prism.The Hongshan and Karamay granites were mainly derived from partial melting of basaltic juvenile lower crust with mixtures of potentially chemical weathered ancient crustal residues and mantle basaltic melt(induced by hot intruding mantle basaltic magma at the bottom of the Baogutu continental arc).On the other hand,the Miaoergou charnockite might be sourced from a deeper partial melting reservoir under the accretionary prism,consisting of the low-temperature altered oceanic crust,juvenile oceanic sediments,and mantle basaltic melt.These granites could be related to the asthenosphere's counterflow and upwelling,caused by the break-off and delamination of the subducted oceanic plate beneath the accretionary prism Baogutu continental arc in a post-collisional tectonic setting.展开更多
The fiber reinforced plastics (FRPs) are being used widely in the most diverse applications ranging from the aerospace to the sports goods industry. Drilling in particular is important to facilitate the assembly opera...The fiber reinforced plastics (FRPs) are being used widely in the most diverse applications ranging from the aerospace to the sports goods industry. Drilling in particular is important to facilitate the assembly operations of structurally intricate composite products. The drilling of holes in FRPs leads to drilling induced damage which is an important research area. The researchers worldwide have tried to minimize the damage by optimizing the operating variables, and tool designs as well as by developing unconventional methods of hole making. Most of the work done so far has been experimental in nature with little or no focus on numerical simulation of the drilling behavior of FRPs. In the present research endeavor, a finite element model has been developed to investigate the drilling induced damage of FRP laminates.展开更多
A numerical method of integration of Green’s functions of strip element method (SEM) is proposed The response of ultrasonic source generated by a transducer on the surface of a multi ply composite plate containing a ...A numerical method of integration of Green’s functions of strip element method (SEM) is proposed The response of ultrasonic source generated by a transducer on the surface of a multi ply composite plate containing a delamination is analyzed by the use of SEM The numerical results show that the scanning features of the ultrasonic waves may be used to identify the delamination inside the composite plate.展开更多
The purpose of the present study is to develop a new finite element method for analyzing buckling of delaminated composite plates and shells. This is achieved by establishing a new finite element called the reference_...The purpose of the present study is to develop a new finite element method for analyzing buckling of delaminated composite plates and shells. This is achieved by establishing a new finite element called the reference_surface element. By use of the compatibility condition under Mindlin assumptions, the formulation of the reference_surface element was derived from whichever plate_element or shell_element being capable of analyzing composite plates and shells. This method assures a reasonable description of displacement field and the satisfaction of compatibility conditions for delamination problem. Numerical results for linear delamination buckling of axially compressed shells are presented to validate the method.展开更多
The buckling and post-buckling of clamped circular plate subjected to distributed radialcompressed load is presented by using the high-order perturbation analysis and shooting method.Thesixth-order solution shows good...The buckling and post-buckling of clamped circular plate subjected to distributed radialcompressed load is presented by using the high-order perturbation analysis and shooting method.Thesixth-order solution shows good agreement with the FEM results in[11].The results in this paper areapplied to investisate the budding and growth of pressed thin film delamination in the film/substratesystem.Under a certain residual pressure in the thin film,two characteristic blister radii R_c and R_s,thecritical radius and growing radius respectively,are obtained.The numerical result shows that thegrowth criterion of delamination in [9,10] is not perfect.In variant residual stress or interface tough-hess,the conditions of no growth,stable growth and unstable growth of the delamination are obtainedby comparing the driving force at the interface crack tip with the interface toughness.展开更多
Prelithiation has been intensively investigated in high-capacity lithiumion batteries(LIBs).However,the optimization of prelithiation degrees for long service life of LIBs still remains a challenge.The positive effect...Prelithiation has been intensively investigated in high-capacity lithiumion batteries(LIBs).However,the optimization of prelithiation degrees for long service life of LIBs still remains a challenge.The positive effect of prelithiation on suppressing degradation of LIBs,besides directly pursuing the high first Coulomb efficiency which has been widely reported in the literature,is revealed and discussed based on an analytical model focusing on the interfacial delamination in electrodes.For full charge-discharge cycling,well-designed prelithiation can effectively suppress the delamination and reduce the debonding size by approximately 25%,compared with the case without prelithiation.For the strategy combining partial charge-discharge cycling and prelithiation,the largest reversible capacity without debonding can be significantly improved by approximately100%with well-designed prelithiation.This work is expected to provide a prelithiation design principle and further improve the mechanical stability of LIB electrodes.展开更多
基金supported by the Natural Science Foundation of Shandong Province(Grant No.ZR2022QD055)the Taishan Scholars(Grant No.tstp 20231214)the National Natural Science Foundation of China(Grant No.42372247).
文摘Post-collisional magmatism contains important clues for understanding the reworking and growth of continental crust,as well as lithospheric delamination and orogenic collapse.Early Devonian magmatism has been identified in the North Qilian Orogenic Belt(NQOB).This paper reports an integrated study of petrology,whole-rock geochemistry,Sm-Nd isotope and zircon U-Pb dating,as well as Lu-Hf isotopic data,for two Early Devonian intrusive plutons.The Yongchang and Chijin granites yield zircon U-Pb ages of 394-407 Ma and 414 Ma,respectively.Both of them are characterized by weakly peraluminous to metaluminous without typical aluminium-rich minerals,LREE-enriched patterns with negative Eu anomalies and a negative correlation between P_(2)O_(5) and SiO_(2) contents,consistent with geochemical features of I-type granitoids.Zircons from the studied granites display negative to weak positive ε_(Hf)(t)values(−5.7 to 2.1),which agree well with those of negative ε_(Nd)(t)values(−6.4 to−2.9)for the whole-rock samples,indicating that they were derived from the partial melting of Mesoproterozoic crust.Furthermore,low Sr/Y ratios(1.13-21.28)and high zircon saturation temperatures(745℃ to 839℃,with the majority being>800℃)demonstrated a relatively shallow depth level below the garnet stability field and an additional heat source.Taken together,the Early Devonian granitic magmatism could have been produced by the partial melting of ancient crustal materials heated by mantle-derived magmas at high-temperature and low-pressure conditions during postcollisional extensional collapse.The data obtained in this study,when viewed in conjunction with previous studies,provides more information about the tectonic processes that followed the closure of the North Qilian Ocean.The tectonic transition from continental collision to post-collisional delamination could be constrained to~430 Ma,which is provided by the sudden decrease of Sr/Y and La/Yb ratios and an increase in zircon ε_(Hf)(t)values for granitoids.A two-stage tectonic evolution model from continental collision to post-collisional extensional collapse for the NQOB includes(a)continental collision and crustal thickening during ca.455-430 Ma,characterized by granulite-facies metamorphism and widespread low-Mg adakitic magmatism;(b)post-collisional delamination of thickened continental crust and extensional collapse of orogen during ca.430-390 Ma,provided by coeval high-Mg adakitic magmatism,A-type granites and I-type granitoids with low Sr-Y ratios.
基金National Natural Science Foundation of China(Grant Nos.52275096,52005108,52275523)Fuzhou-Xiamen-Quanzhou National Independent Innovation Demonstration Zone High-end Equipment Vibration and Noise Detection and Fault Diagnosis Collaborative Innovation Platform ProjectFujian Provincial Major Research Project(Grant No.2022HZ024005)。
文摘The use of terahertz time-domain spectroscopy(THz-TDS)for the nondestructive testing and evaluation(NDT&E)of materials and structural systems has attracted significant attention over the past two decades due to its superior spatial resolution and capabilities of detecting and characterizing defects and structural damage in non-conducting materials.In this study,the THz-TDS system is used to detect,localize and evaluate hidden multi-delamination defects(i.e.,a three-level multi-delamination system)in multilayered GFRP composite laminates.To obtain accurate results,a wavelet shrinkage de-noising algorithm is used to remove the noise from the measured time-of-flight(TOF)signals.The thickness and location of each delamination defect in the z-direction(i.e.,through-the-thickness direction)are calculated from the de-noised TOF signals considering the interaction between the pulsed THz waves and the different interfaces in the GFRP composite laminates.A comparison between the actual and the measured thickness values of the delamination defects before and after the wavelet shrinkage denoising process indicates that the latter provides better results with less than 3.712%relative error,while the relative error of the non-de-noised signals reaches 16.388%.Also,the power and absorbance levels of the THz waves at every interface with different refractive indices in the GFRP composite laminates are evaluated based on analytical and experimental approaches.The present study provides an adequate theoretical analysis that could help NDT&E specialists to estimate the maximum thickness of GFRP composite materials and/or structures with different interfaces that can be evaluated by the THz-TDS.Also,the accuracy of the obtained results highlights the capabilities of the THz-TDS for the NDT&E of multilayered GFRP composite laminates.
基金National Natural Science F oundation of China !( No.1980 2 0 0 1)
文摘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 P min =-0.45kN is also measured to verify the estimated result of fatigue life.
基金Project supported by the Fundamental Materials Development funded by the Korean Ministry of Knowledge Economy
文摘Cu/Al bar clad material was fabricated by a drawing process and a subsequent heat treatment.During these processes,intermetallic compounds have been formed at the interface of Cu/Al and have affected its bonding property.Microstructures of Cu/Al interfaces were observed by OM,SEM and EDX Analyser in order to investigate the bonding properties of the material.According to the microstructure a series of diffusion layers were observed at the interface and the thicknesses of diffusion layers have increased with aging time as a result of the diffusion bonding.The interfaces were composed of 3-ply diffusion layers and their compositions were changed with aging time at 400 °C.These compositional compounds were revealed to be η2,(θ+η2),(α+θ) intermetallic phases.It is evident from V-notch impact tests that the growth of the brittle diffusion layers with the increasing aging time directly influenced delamination distance between the Cu sleeve and the Al core.It is suggested that the proper holding time at 400 °C for aging as post heat treatment of a drawn Cu/Al bar clad material would be within 1 h.
文摘By employing the two-dimensional analysis, i.e.,plane strain and plane stress, a semi-analytical method is developed to investigate the interfacial delamination in electrodes. The key parameters are obtained from the governing equations, and their effects on the evolution of the delamination are evaluated. The impact of constraint perpendicular to the plane is also investigated by comparing the plane strain and plane stress. It is found that the delamination in the plane strain condition occurs easier, indicating that the constraint is harmful to maintain the structure stability. According to the obtained governing equations, a formula of the dimensionless critical size for delamination is provided, which is a function of the maximum volumetric strain and the Poisson's ratio of the active layer.
基金The project supported by post doctoral science foundation of China
文摘In this paper, the problem of axisymmetric buckling and postbuckling of a circular thin-film delamination bridged by through-thickness fiber tows in 3D composites is presented. An iterativeprocedure based on Taylor’s series expansion is used to generate a family of nondimensionalized post-buckling solutions of the above problem by yon Karman’s nonlinear plate theory. Attention is fo-cused, herein, on the effects of the bridge force of through-thickness fibers on the buckling and post-buckling behavior of the delamination. It is found that fiber bridge not only increases the ability of re-sisting delamination buckling and postbuckling, but also brings on the jump of the delamination deflec-tion mode during the postbuckling phase. Consequently the behavior of the composite structure with de-lamination is greatly improved, such as increasing the residual strength and prolonging the service life.
基金supported by Technical Education Quality Improvement Programme (TEQIP-II) of Motilal Nehru National Institute of Technology Allahabad,Allahabad (U.P.),India financiallyby Invertis University,Bareilly,(U.P.),India
文摘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.
基金financially supported by National Key R&D Program of China(Grant No.2017YFC0601402)
文摘The East Asia continent is characterized by a mosaic architecture with various composing blocks,such as the North and South China blocks,which had been collaged in Late Permian to Triassic in response to the break-up of Pangea.In the Late Mesozoic.
基金the AdFutura Scholarship provided by the Slovene Human Resources Development and Scholarship Fund for this workthe Clarendon and Balliol Jowett Scholarships for subsequent funding+1 种基金SCG Chemicals Co., Ltd. (Thailand)SCG Packaging Co. Ltd PLC, for funding
文摘A new solvothermal post-synthesis treatment for preparing high aspect ratio magnesium aluminium layered double hydroxides(Mg Al–LDHs) has been developed. Treating laurate-intercalated Mg Al–LDHs in pure ethanol in an autoclave for 48 h at 150 °C was found to produce delaminated MgA l–LDH nanosheets with a thickness of ~2.6 nm and an aspect ratio of ~105. It is proposed that the high pressure solvothermal process promotes the insertion of ethanol molecules into the LDH interlayer space, thereby facilitating delamination. This new post-synthesis treatment provides the opportunity for a facile, large scale route to highly delaminated high aspect ratio LDHs, which might be of interest towards novel nanomaterials for energy conversion and storage.
文摘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.
基金supported by the National Natural Science Foundation of China(Grants 11622217 and 11872196)the National Program for Special Support of Top-Notch Young Professionalssupported by the Fundamental Research Funds for the Central Universities(Grants lzujbky-2017-ot18,lzujbky-2017-k18,and lzujbky-2018-9)
文摘For the application of second generation high temperature superconducting coated conductors (CCs) with layered structures, thermal mismatch between different components and electromagnetic force exerted in superconducting layer in a working magnet can cause transverse tensile stress, which would result in delamination behavior. Therefore many research groups have designed experiments to measure the delamination strength and dedicate to improving that. However, the reason of the discrete distribution of measured data has still not get quantitatively studied, besides, there are lack of investigations on the method of changing depositing conditions to improve the delamination strength except by adding an additional metal layer. In this work, we adopt an anvil test device and obtain delamination strengths as 29.6 MPa of YBa2Cu3O7-x (YBCO)/buffer and 114.6 MPa of buffer/substrate by combing energy disperse spectroscopy (EDS) detection. The reason of discretized measurement data on the delamination strength is explained. Moreover, we find that different temperatures during Ag deposition determine the bonding force of Ag and YBCO layer. The Delamination strength between Ag and YBCO layer increases from 4.4 MPa to larger than 114.6 MPa with temperature elevated from 30℃ to 100℃. Hence we present a novel method for improving the delamination strength of YBCO CCs by setting an optimal temperature of Ag deposition.
基金supported by the National Natural Science Foundation of China(Nos.11672084,11602072,and 11372086)the Natural Science Foundation of Guangdong Province of China(Nos.2016A030311006 and 2016A030310367)the Research Innovation Fund of Shenzhen City of China(Nos.JCYJ20170413104256729 and JCYJ20170811160538023)
文摘A fracture mechanics analysis is conducted for a delamination problem of a multilayered thermoelectric material(TEM) that consists of an n-type layer and a p-type layer sandwiched by an insulating layer. A time-varying energy release rate is presented when the n-type layer delaminates from the insulating layer. Effects of the temperature difference across the system and the applied electric current on the energy release rate are identified. The influence of the thickness ratio of the insulating layer to the thermoelectric(TE) layer is also examined. Based on the energy release rate criterion,the critical temperature difference for delamination propagation is obtained. Some useful conclusions are given.
基金the financial support of Aeronautical Science Foundations of China(No.2013ZE52067,No.2014ZE52057)
文摘Exit delamination is excessive drilling thrust force.Therefore,it is necessary to investigate the critical thrust force which cause exit delamination when carbon fibre reinforced plastics(CRFP)is drilled.According to the linear elastic fracture mechanics,the mechanics of composite material and the classical thin plate bending theory,a common theoretical model of the critical drilling thrust force for CFRP plates is established.Compared with the experimental data of previous studies,the results show that the theoretical values agree well with the experimental values.This model can be used to forecast the critical thrust force for the drilling-induced delamination of CFRP.
基金jointly supported by the National Natural Science Foundation of China (41802093)the National Key Research and Development Program of China (2017YFC0601201 and 2018YFC0604002)+2 种基金the Project of Xinjiang Bureau of Geology and Mineral Resources (2011BAB06B03-3)the Project of China Geological Survey (DD20190405 and DD20190406)the Fundamental Research Funds for the Central Universities, Sun Yat-sen University (2021qntd23).
文摘The A-type granites with highly positiveε_(Nd)(t)values in the West Junggar,Central Asian Orogenic Belt(CAOB),have long been perceived as a group formed under the same tectonic and geodynamic setting,magmatic sourceq and petrogenetic model.Geological evidence shows that these granites occurred at two different tectonic units related to the southeastern subduction of Junggar oceanic plate:the Hongshan and Karamay granites emplaced in the southeast of West Junggar in the Baogutu continental arc;whereas the Akebasitao and Miaoergou granites formed in the accretionary prism.Here the authors present new bulk-rock geochemistry and Sr-Nd isotopes,zircon U-Pb ages and Hf-O isotopes data on these granites.The granites in the Baogutu continental arc and accretionary prism contain similar zirconε_(Hf)(t)values(+10.9 to+16.2)and bulk-rock geochemical characteristics(high SiO_(2)and K_(2)O contents,enriched LILEs(except Sr),depleted Sr,Ta and Ti,and negative anomalies in Ce and Eu).The Hongshan and Karamay granites in the Baogutu continental arc have older zircon U-Pb ages(315-305 Ma)and moderate^(18)O enrichments(δ^(18)_(O_(zircon))=+6.41‰-+7.96‰);whereas the Akebasitao and Miaoergou granites in the accretionary prism have younger zircon U-Pb ages(305-301 Ma)with higher^(18)O enrichments(δ^(18)_(O_(zircon))=+8.72‰-+9.89‰).The authors deduce that the elevated^(18)O enrichments of the Akebasitao and Miaoergou granites were probably inherited from low-temperature altered oceanic crusts.The Akebasitao and Miaoergou granites were originated from partial melting of low-temperature altered oceanic crusts with juvenile oceanic sediments below the accretionary prism.The Hongshan and Karamay granites were mainly derived from partial melting of basaltic juvenile lower crust with mixtures of potentially chemical weathered ancient crustal residues and mantle basaltic melt(induced by hot intruding mantle basaltic magma at the bottom of the Baogutu continental arc).On the other hand,the Miaoergou charnockite might be sourced from a deeper partial melting reservoir under the accretionary prism,consisting of the low-temperature altered oceanic crust,juvenile oceanic sediments,and mantle basaltic melt.These granites could be related to the asthenosphere's counterflow and upwelling,caused by the break-off and delamination of the subducted oceanic plate beneath the accretionary prism Baogutu continental arc in a post-collisional tectonic setting.
文摘The fiber reinforced plastics (FRPs) are being used widely in the most diverse applications ranging from the aerospace to the sports goods industry. Drilling in particular is important to facilitate the assembly operations of structurally intricate composite products. The drilling of holes in FRPs leads to drilling induced damage which is an important research area. The researchers worldwide have tried to minimize the damage by optimizing the operating variables, and tool designs as well as by developing unconventional methods of hole making. Most of the work done so far has been experimental in nature with little or no focus on numerical simulation of the drilling behavior of FRPs. In the present research endeavor, a finite element model has been developed to investigate the drilling induced damage of FRP laminates.
基金This project is supported by National Natural Science Foundation of China(No19872011).
文摘A numerical method of integration of Green’s functions of strip element method (SEM) is proposed The response of ultrasonic source generated by a transducer on the surface of a multi ply composite plate containing a delamination is analyzed by the use of SEM The numerical results show that the scanning features of the ultrasonic waves may be used to identify the delamination inside the composite plate.
文摘The purpose of the present study is to develop a new finite element method for analyzing buckling of delaminated composite plates and shells. This is achieved by establishing a new finite element called the reference_surface element. By use of the compatibility condition under Mindlin assumptions, the formulation of the reference_surface element was derived from whichever plate_element or shell_element being capable of analyzing composite plates and shells. This method assures a reasonable description of displacement field and the satisfaction of compatibility conditions for delamination problem. Numerical results for linear delamination buckling of axially compressed shells are presented to validate the method.
文摘The buckling and post-buckling of clamped circular plate subjected to distributed radialcompressed load is presented by using the high-order perturbation analysis and shooting method.Thesixth-order solution shows good agreement with the FEM results in[11].The results in this paper areapplied to investisate the budding and growth of pressed thin film delamination in the film/substratesystem.Under a certain residual pressure in the thin film,two characteristic blister radii R_c and R_s,thecritical radius and growing radius respectively,are obtained.The numerical result shows that thegrowth criterion of delamination in [9,10] is not perfect.In variant residual stress or interface tough-hess,the conditions of no growth,stable growth and unstable growth of the delamination are obtainedby comparing the driving force at the interface crack tip with the interface toughness.
基金the National Natural Science Foundation of China(Nos.12072183,11872236 and 12172205)。
文摘Prelithiation has been intensively investigated in high-capacity lithiumion batteries(LIBs).However,the optimization of prelithiation degrees for long service life of LIBs still remains a challenge.The positive effect of prelithiation on suppressing degradation of LIBs,besides directly pursuing the high first Coulomb efficiency which has been widely reported in the literature,is revealed and discussed based on an analytical model focusing on the interfacial delamination in electrodes.For full charge-discharge cycling,well-designed prelithiation can effectively suppress the delamination and reduce the debonding size by approximately 25%,compared with the case without prelithiation.For the strategy combining partial charge-discharge cycling and prelithiation,the largest reversible capacity without debonding can be significantly improved by approximately100%with well-designed prelithiation.This work is expected to provide a prelithiation design principle and further improve the mechanical stability of LIB electrodes.