bluuebunny/crossref_metadata_2025 huggingface dataset:
Synthesis and Characterization of Modified Epoxy Resin/Modified Nano-SiO2 Composite
Authors: Mo Zunli , Pu Bin , Meng Shujuan , Zhang Chun , Xie Tingting , Jiang Caidi
Published: January 2019

Modified epoxy resin/modified nano-SiO2 composite was prepared employing urethane acrylate to modify epoxy resin E-44 and silane coupling agent for the modification of SiO2 nanoparticles. The obtained materials were characterized by Fourier Transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), mechanical strength test and hardness test. The composite displayed a significantly increased mechanical properties and great application prospects in dental materials.
Wear Characterization of Aluminium Metal Matrix Composites
Authors: Vijayakumar S. , Karunamoorthy L.
Published: January 2019

Aluminium metal matrix composites wear characterization is presented in the paper. The LM25 grade aluminium alloy is chosen as matrix material and reinforcements are silicon carbide, zircon and garnet particles. AlMMCs are produced by conventional stir casting method and heat treated before making wear test specimens according to the ASTM G99 standards. The wear behaviour of these composites is studied under laboratory conditions using a pin-on-disc wear test rig. The wear behaviour of these composites is studied under sliding on EN32 steel disc. The influence of reinforcement type, volume fraction, particle size, sliding speed, applied load and sliding distance is analyzed.
Study of Thermal Properties of Rice Husk Polypropylene (RHPP) Composites
Authors: Kumar Vinay , Saini Manohar Singh , Kanungo Bikram Kishore , Sinha Shishir
Published: January 2019

Abundantly available rice husk was used to reinforce polypropylene for the development of rice husk polypropylene composites (RHPP) by extrusion and compression molding techniques. Maleic anhydride polypropylene (MAPP) compatibilizer and titanate coupling agent were used to improve the adhesion between rice husk and polypropylene. Effect of fillers such as mica, talc, zirconium oxide, silica and calcium carbonate on thermal properties of RHPP composites was studied. Improvement in heat deflection temperature (HDT), degradation temperature of RHPP was observed but enthalpies of melting and degradation decreased by the addition of these fillers. No significant change in melting point of composites was noticed by the addition of these fillers. Composites thus prepared to have applications in building, automobile, and sport sectors.
Effect of Cenosphere Filler on Damping Properties of Bamboo-Epoxy Laminated Composites
Authors: Jena Hemalata , Pradhan Arun Kumar , Pandit Mihir Kumar
Published: January 2019

This paper deals with evaluation of damping properties of natural fibre composites consisting of bamboo fibre as reinforcement, epoxy as matrix and cenosphere as particulate filler. Hand lay-up technique is used to fabricate the composites with varying number of layers and different weight percentage of cenosphere filler. The prepared specimens are subjected to free vibration test (FVT) to investigate the damping ratio and natural frequency. Damping of the bamboo–epoxy composites is analysed experimentally using cantilever beam test set up by impulse technique. The investigation reveals that the number of layers and cenosphere filler content influences the natural frequency and the damping ratio.
Multi-Objective Optimization of Laminated Composite Plate with Diffused Layer Angles using Non-Dominated Sorting Genetic Algorithm (NSGA-II)
Authors: Nicholas P. Emmanuel , Padmanaban K.P. , Babu M.C. Lenin
Published: January 2019

An approach to design the laminated composite plate subjected to in-plane loading conditions is investigated. The composite structure is optimized for the conflicting multi-objectives maximum buckling load factor and minimum weight. Fibre orientation angles, stacking sequence and number of layers are chosen as design variables. In order to avoid the inter-laminar stress developed due to grouping of plies, design of laminated plate with diffused stacking sequences is proposed in this work. In-plane strength of the laminate and not grouping more than four plies of same orientation are set as the design constraints. Static failure criteria (Tsai-Wu and Maximum Stress) are used to determine the load bearing capacity for a configuration generated during the optimization process. The effectiveness of the proposed approach is explored with two optimization problems. In the first problem a simple genetic algorithm (SGA) is applied to maximize the buckling load factor of the composite plate. In the second problem, a multi-objective genetic algorithm (NSGA-II) is used to obtain Pareto optimal designs for the problem having multiple, conflicting, objectives minimum weight and maximum buckling load factor. The results show that better design can be obtained with diffused angle layers and the grouping of plies can also be completely eliminated.
A New Class of Thin Composite Parts for Small Batch Productions
Authors: Bellini C. , Polini W. , Sorrentino
Published: January 2019

During the manufacturing process of polymeric composite materials, geometric unconformities may arise due to the onset of residual stresses, that are due to the chemical shrinkage of the matrix, to the polymerization process and to the difference in value between the CTE of matrix and that of fibres during cooling. The behaviour of thin non-planar form laminates (L, T, U shapes) is not the same of flat ones: even if the laminate presents a symmetrical and balanced structure, the condition of stresses and deformations is more complex and causes geometric deviations. The solution currently used to solve this problem is the equipment compensation. In this paper a new class of thin composite parts is presented. It consists of prepreg laminate stratified around an aluminium core, which serves as mould. In this way a new L-shape laminate may be developed for example. Experimental tests were carried out to produce the new class of composite parts. The obtained results demonstrated that the new class of thin composite parts is characterized by reduced geometrical unconformities. Moreover, it does not require an external forming mould, that is geometrically very complex, but an internal one, that is an aluminium core. The aluminium core is cheap, but it remains inside the part; therefore, the new class of parts is not adapt to large batch production. Finally, the new class presents a thermo-mechanical behaviour so simple that it is possible to foresee it numerically.
Characterisation of Impact Damage of Composite Structures Using Wavelet-Based Fusion of Ultrasonic and Optical Images
Authors: Katunin Andrzej , Kostka Pawel
Published: January 2019

This paper presents the novel approach for the impact damage characterisation of composite structures, which is based on fusion of ultrasonic scans and optical images. Both internal (inter-fibre failure, fibre failure, delaminations) and external (scratches and surface cracks) damages occurred in the composite structures during their operation need to be analysed due to their occurrence on both of these levels, especially in the case of impact damages. The presented approach allows for the improvement of the characterisation quality, i.e. the whole damaged area could be detected and localized. In order to assure the proper damage identification the wavelet-based fusion with application of appropriate wavelets and parameters of a fusion algorithm was used, which allows for distinction of different types of damages and overall improvement of the resulted image with respect to the human perception capability. The approach was validated experimentally on the glass-epoxy laminated plates after the low-velocity impacts. Representative cases of damaged structure were presented and analysed.
Buckling of the Composite Laminates under Mechanical Loads with Different Layups using Different Plate Theories
Authors: Torabizadeh Mohammad Amin
Published: January 2019

An analytical and numerical solution for general laminated composite plates under mechanical loading is presented based on different lamination plate theories (CLPT and FSDT). General lamination was evaluated by assumption of cross-ply and angle-ply laminated plates. In order to this, Navier-type method and simply supported boundary conditions for rectangular laminates are applied. As a verification method, a finite element code using ANS YS is also developed. Effects of lamination scheme, axial load direction, modulus ratio, plate aspect ratio and lamination angle on critical buckling loads of laminated composite are also investigated and good agreement is found between evaluated results and those available in open literature.
Apparent Interlaminar Shear Strength Measurement by Four Point Short Beam Test
Authors: Aslan Züleyha
Published: January 2019

The main purpose of this investigation is to characterize experimentally the interlaminar shear strength of cross-ply and quasi-isotropic E-glass/epoxy composites by the four point short beam test. ASTM D2344-three point short beam strength test results and the four point short beam strength test results are compared. To determine the details of the four point short beam test, the effects of support span to thickness ratio, load span, ply number, width and fibre orientation on the interlaminar shear strength are investigated. According to the test results the four point short beam test is more advantageous and more convenient than the three point short beam test because of the better load distribution and higher support span to thickness ratio. It is concluded that the support span to thickness ratio should be 8 to obtain pure interlaminar shear failure. The distance between the two loading cylinders should be one half of the support span instead of one third of the support span. When measuring the interlaminar shear strength for E-glass/epoxy laminates, the ply number and the width of the specimen should be chosen carefully.
Mechanical Properties of Short and Continuous Kenaf/Pet Fibre Reinforced Polyoxymethylene Composite
Authors: Dan-mallam Yakubu , Abdullah Mohamad Zaki , Yusoff Puteri Sri Melor Megat
Published: January 2019

The challenges of improving the mechanical properties of natural fibre composites cannot be over emphasized due to fibre geometry, poor fiber distribution in the matrix, the hydrophilic nature of natural fibers and poor fibre–matrix interfacial adhesion. The primary objective of this research is to study the influence of fibre length on mechanical properties of kenaf/PET fibre reinforced POM and to study the effect of hybridization on mechanical properties of the composites. The composites were produced by compression molding and subsequently subjected to tensile, flexural and impact tests according to their respective ASTM standards. The tensile strength of short POM/kenaf/PET (80/10/10) hybrid composite dropped by approximately 33% from 61.8 MPa to 41.3 MPa compared to neat POM. However, the tensile strength of continuous POM/kenaf composites increased significantly by approximately 127% and 107% for 70/30 and 80/20 compositions compared to neat POM. The flexural moduli of short POM/kenaf/PET (70/15/15) hybrid composite and continuous POM/kenaf (70/30) composite improved by approximately 41% and 29%, respectively. The impact strength substantially increased by nearly 161% in continuous POM/kenaf/PET (70/15/15) hybrid composite and 30% in POM/kenaf (80/20) composite. The results show that tensile, flexural and impact properties of the continuous POM/kenaf composites are superior to the short fiber composites, and the influence of hybridization, made a positive impact by enhancing the flexural and impact properties of the composites.
In-Situ Monitoring of Interlaminar Shear Damage in Carbon Fibre Composites
Authors: Zhang Han , Liu Yi , Bilotti Emiliano , Peijs Ton
Published: January 2019

The in-situ damage sensing of carbon/epoxy composites during interlaminar shear testing is investigated. Next to direct monitoring of woven fabric carbon/epoxy reference laminates, the introduction of carbon nanotubes (CNTs) onto these carbon fibre fabrics via a spray coating technique for damage sensing is evaluated. We observed very different sensing behaviour compared to previous studies, which is believed to be more useful for real applications. Through-thickness measurements showed for both reference and CNT modified specimens a continuous increase in electrical resistivity, due to reduced contact areas and conductive pathways. The effect of the introduced CNT network at the interfacial region is also been compared and analysed.
Wrinkling Phenomenon during Uniaxial Extension of a Woven Thermoplastic Composite
Authors: Zanjani Nima A. , Kalyanasundaram Shankar
Published: January 2019

In the current research, wrinkling behaviour of a pre-consolidated woven self-reinforced polypropylene (SRPP) composite is investigated. Specimens possessing different aspect ratios were uniaxially extended at room temperature. Principal strains were recorded by a 3D optical photogrammetric system. Continuous measurement of out-of-plane displacements and induced in-plane strains elucidated the effect of specimens’ aspect ratios on wrinkling behaviour of SRPP composite. Investigating the evolution of meridian strains offered a valuable insight into development of principal strains before and after wrinkling onset. Plotting major and minor strains in a 2D strain space clarified the role of different deformation modes in the evolution of wrinkles. It was shown that common wrinkling predictors used on metals cannot effectively predict wrinkling initiation in this class of composites and a more reliable measure, based on evolution of local strains, should be employed. The current study investigates the wrinkling behaviour of a woven thermoplastic composite for the first time through a modified Yoshida buckling experiment. The outcomes illustrated effective parameters on the wrinkling evolution in SRPP specimens.
Synthesis of Zinc Oxide and Titanium Dioxide Composite Nanorods and Their Photocatalytic Properties
Authors: Pei L. Z. , Wei T. , Lin N. , Yu H. Y.
Published: January 2019

Zinc oxide and titanium dioxide composite nanorods have been synthesized by the hydrothermal process using zinc acetate and titanium butoxide as the raw materials. X-ray diffraction (XRD) shows that the composite nanorods are composed of hexagonal ZnO and tetragonal TiO2 phases. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images show that the length and diameter of the composite nanorods are 1–5 μm and 80–350 nm, respectively. Hydrothermal temperature and duration time have important roles in the formation of the composite nanorods. Using rhodamine B (RB) degradation as the probe reaction, the photocatalytic activities of the composite nanorods under UV light irradiation have been analysed. The roles of the irradiation time, content of the composite nanorods and RB concentration in the photocatalytic activities of the composite nanorods have been investigated. 10 mL 10 mgL−1 RB solution can be totally degraded using 10 mg composite nanorods under UV light irradiation for 90 min.
Modification of Carbon Fibre/Epoxy Composites by Polyvinyl Alcohol (PVA) Based Electrospun Nanofibres
Authors: Beylergi̇l Bertan , Tanoğlu Metin , Aktaş Engin
Published: January 2019

In this study, the effects of modifying interlaminar region of unidirectional carbon fibre/epoxy composites by the incorporation of electrospun polyvinyl alcohol (PVA) nanofibres were investigated. PVA nanofibres were directly deposited onto the carbon fabrics by electrospinning method to improve mechanical performance of those composites. The features of the electrospun nanofibres were characterized by microscopy techniques. The unidirectional carbon fibre/epoxy composite laminates with/without PVA nanofibre interlayers were manufactured by vacuum-infusion technique in a [0]4 configuration. Tensile, three-point bending, compression, Charpy-impact and Mode-I fracture toughness tests (Double Cantilever Beam (DCB)) were carried out in accordance with ASTM standards to evaluate mechanical performance of the composites. Scanning electron microscopy (SEM) observations were made on the specimens to evaluate microstructural features. It was observed that the carbon fabrics were successfully coated with a thin layer of PVA nanofibres by electrospinning technique. The results showed that PVA nanofibres improve the mechanical properties of unidirectional carbon/epoxy composite laminates when subjected to in-plane loading. On the other hand, PVA nanofibres slightly reduced the mode-I fracture toughness values although they led to more stable crack propagation.
Delamination Detection in Composite T-Joints of Wind Turbine Blades using Microwaves
Authors: Li Zhen , Haigh Arthur , Soutis Constantinos , Gibson Andrew , Sloan Robin , Karimian Noushin
Published: January 2019

The wind turbine is playing an increasingly important role in the generation of green electricity. The structural integrity and maintenance of the wind turbine blade is a critical issue in service due to the harsh operating environments. In this paper, the delamination in glass fibre composite joints of a wind turbine blade is detected using the non-contact microwave imaging with an open-ended waveguide. The existence and extent of the delaminated region could be found from the generated images. Thickness variation and the presence of the web can be identified as well. The optimum inspection frequency range is investigated, which offers a reference for future applications. By comparison, the phase profiling provided by the scanning shows better performance for the delamination detection rather than the magnitude profiling.
Mechanical Characterization of Sandwich Composite Structure using a New Experimental Approach
Authors: Alila F. , Fajoui J. , Kchaou M. , Casari P. , Wali N. , Gerard R.
Published: January 2019

In marine construction, ship hulls are subjected to high fatigue stresses due to the impact of waves and their cyclic solicitations. However, fatigue behaviour evaluation of the constitutive materials of hull is based on standard tests. The objective of this study is to take a critical view on the current standard test method set to investigate the fatigue life of cellular foam core material as used in high performance sandwich materials. The highlight of this study is to develop a new geometry of specimen in order to achieve coherence between the actual fatigue life time of the real structure and the one of specimens tested in a controlled laboratory environment. The tested specimen is made out of a high-density foam core and thin glass fabric faces. Moreover, a new test rig of different flexure types, in quasi-static or fatigue loadings on sandwich specimens, was developed and validated.
Influence of Textile Parameters on the Out-of-Plane Permeability of Carbon Fiber Non-Crimp Fabrics
Authors: Arnold M. , Gortner F. , Cojutti M. , Wahl M. , Mitschang P.
Published: January 2019

Within the last years, liquid composite molding (LCM) is gaining more and more importance for the automotive industry due to weight saving of (semi-)structural car parts. In order to make carbon fibre parts economically more interesting for this area, short cycle times are necessary. Hence, one concept is the impregnation of carbon fibre parts in through-the-thickness direction. The behaviour of the impregnability depends mainly on the out-of-plane permeability of the fabric. The permeability of the fabric is mainly influenced by the fibre type, orientation of the fibres, and the stitching parameters.

In this study the influence of textile parameters on the out-of-plane permeability of 45° and 0°/90° biaxial carbon fibre non-crimp fabrics (NCF) was investigated. The stitching yarn parameters (linear mass density and stitch length) were varied to see the influence on the out-of-plane permeability. The out-of-plane permeability was measured using a measurement cell based on flow front monitoring with ultrasonic technology at a minimum of three different fibre volume contents between 47 % and 63 % to show the decrease of permeability with respect to the fibre volume content.

The results show that the out-of-plane permeability of the 0°/90° carbon fibre NCF are not significantly affected by the yarn linear mass density and the stitch length. Conversely the 45° carbon fibre NCF is affected by the stitch length, but not by the yarn linear mass density.
Static Testing and Analysis of Composite Wing of a Two-Seater Aircraft Powered by Li-Ion Battery Electric Propulsion
Authors: Yang Kang , Zhang Liguo , Ji Shude , Yue Yumei , Ji Wang
Published: January 2019

The present paper studied the strength and deformation characteristics of a composite wing of a two-seater aircraft powered by Li-ion battery electric propulsion. In order to get the airworthiness certificate, the static testing is indispensable. The primary wing structure component includes upper and lower skins, leading edge, trailing edge, a root rib and main spar. The main purpose of static testing is to examine the bending strength of the wing. The testing results are in good agreement with the FE analysis results and the bending strength of wing is strong enough to support the limit loads (the maximum loads to the expected in service) without detrimental and permanent deformation, and without failure for at least 3s under the ultimate loads (limit loads multiplied by prescribed factors of safety), which meets ASTM F2245-11(Standard Specification for Design and Performance of a Light Sport Airplane) enough.
Graphene Encapsulating Boron Nitride Electrostatic Assemblies for Fabrication of Polymer Composites with High Thermal Conductivity
Authors: Huang Tao , Yao Yimin , Meng Fanling
Published: January 2019

In the recent years, significant attention has been focused in insulating electronic encapsulation materials with high thermal conductivity. We fabricated reduced graphene oxide (RGO) encapsulated h-BN hybrids (h-BN@RGO) from the thermal reduction of electrostatically assembled h-BN@GO hybrids. It is found that the addition of h-BN@RGO fillers enhances the thermal conductivity of epoxy resins while preserving the electrical insulation. The thermal conductivity achieve 3.45 W.m−1.K−1, by adding 40 wt% h-BN@RGO, which is enhanced by 1643% compared with that of neat epoxy.
Synthesis and Characterization of TiO2 Reinforced Al6061 Composites
Authors: Kumar G B Veeresh , Gouda P S Shivakumar , Pramod R , Rao C S P
Published: January 2019

This article presents the investigative work carried out to study the relationship between the physical, mechanical and tribological characteristics of aluminum matrix composites reinforced with Titanium dioxide (TiO2). The powder metallurgy route of production was followed to produce the composites (Al6061 containing 3 wt% TiO2). The composites were subjected to sequences of physical, mechanical and tribological investigations. The outputs of the experiments done indicate that the increase in TiO2 fillers increase the density of the composite and the values accepted by the rule of mixtures. The result of mechanical characterisation of Al6061-TiO2 composites was noticed to increase significantly with higher TiO2 content in the matrix, with loss in ductility. The dry sliding wear studies of Al6061-TiO2 composite showed greater wear resistance than Al6061 matrix and the composite containing higher filler content displayed the superior physical, mechanical and tribological characteristics.
Numerical and Experimental Analysis of Umbilical Cables under Tension
Authors: Lu Qingzhen , Chen Jinlong , Yang zhixun , chao Yin Yuan , Yue Qianjin
Published: January 2019

Umbilical cables are composite structures that consisting of metallic material and polymeric material. Analysing tension behaviour under axial loading is a key requirement to design the structure. A full three-dimensional finite element model is established in which the effect of radial deformation is given more attention. A plane finite element analysis is proposed to predict the radial stiffness of the inner core with several components. The tension behaviour of an umbilical cable is analysed by the proposed models. Tension tests of the umbilical cable were carried out. Compared with the available theoretical models in the literature, the finite element model has a satisfactory agreement with the experimental results. In addition, the finite element model is used for the assessment of the influence of the important parameters on the tension behaviour, which is helpful for the design of umbilical cable.
Crack Properties of Press Concrete for Varying Types of Fibre Reinforcement
Authors: Kim Min-Jun , Lee Bum-Sik , Kim Hyeong-Gook , Kim Sang-Woo , Kim Kil-Hee
Published: January 2019

This study evaluates the crack control capacity of press concrete with fibre reinforcement used in underground parking lot. The primary test variable is the types of fibre reinforcement. The mock-up specimens are targeted at the floor of an underground parking lot in subjective to a frequent traffic load, and designed to be 4,000mm long and 3,250 mm wide. Cellulose and nylon fibres are used as fibre reinforcement. The test results showed that the fibre reinforcement used in the study effectively controlled the cracks of specimens due to the increased split tensile strength of specimens and the enhanced adhesion performance between fibres and cement mortar.
Impact Response of Carbon Fibre Fabric/Thermoset-Thermo-Plastic Combined Polymer Composites
Authors: Lee Joon Seok , Kim Jong Won
Published: January 2019

Carbon fibre-reinforced polymer (CFRP) composites are used in various engineering fields with their excellent mechanical properties and lightweight. However, thermoset epoxy composites with brittle epoxy resin system are leading low fracture toughness that caused deterioration during cyclic loading. In addition, the delamination occurred on the thermoset laminated composite material to impact. In this study, to improve these problems, thermoplastic resin added on the top and bottom of thermoset composites and to impregnate two resins that are not compatible on reinforcement, combined prepregs were manufactured for co-curing process. As a result, the formation of thermoplastic layers on the top and bottom of thermoset composites was not significantly affecting much of impact load. However, this improved greatly the energy absorption so that improved fracture toughness.
Multi-Scale Energy Analysis Method during Automated Fibre Placement Process
Authors: Sun Shouzheng , Han Zhenyu , Fu Hongya
Published: January 2019

Automated fibre placement (AFP) is an advanced technology for composite lay-up. However, analysis on mechanical properties used by experiments or macroscopic theories during AFP process suffers from some restrictions, because multi-scale effect of laying tows and their manufacturing defects could not be considered. This contribution proposes a novel anti-sequential multi-scale analysis method based on concurrent/sequential multi-scale analysis method. In order to establish a coupling mechanism among different scales, multi-scale energy transfer model is presented and emphatically analysed through composite mechanics and classical mechanics. Furthermore, taking a Bisphenol A epoxy matrix prepreg tow as an example, an application is employed to verify the feasibility of the method and model. Finally, application field for processing optimization is introduced and prospected.
Enhanced Microwave Absorption of Quartic Layered Epoxy-Mwcnt Composite for Radar Applications
Authors: Naidu M. K. , Ramji K. , Santhosi B. V. S. R. N. , Shami TC , Baskey Himangshu B , Satyanarayana B.
Published: January 2019

In this paper we presented the electromagnetic analysis of multilayered Radar Absorbing Structure (RAS) composed of Multi-Wall Carbon Nano Tubes (MWCNTs) with different weight percentages. The complex permittivity and permeability of MWCNT/epoxy composites with different wt% are analysed and the microwave absorbing characteristics are evaluated. The permittivity and permeability of MWCNT composites increased with increase in MWCNT concentration. Absorption properties like reflection loss of multilayered RAS are estimated analytically using electromagnetic wave theory for different layers and with different layer order based on impedance matching condition. The quartic layer MWCNT/epoxy composite achieves a better microwave absorption when compared to other multilayer RAS. The microwave absorption was attributed to dielectric loss of the material. The simulated quartic layer RAS is fabricated and validation of reflection loss is done experimentally using free space measurement technique. From free space measurement the minimum reflection loss in entire X-band is observed to be approximately −12 dB (95% of absorption), −15 dB (97% of absorption), with 3 GHz band width, −20 dB (99% of absorption) with 2 GHz bandwidth and maximum peak of - 44 dB at 11.5 GHz. Hence the composite material has great potential of application as highly efficient microwave absorber.
The Use of Vibrothermography for Detecting and Sizing low Energy Impact Damage of Cfrp Laminate
Authors: Li Yin , Tian Gan , Yang Zheng-wei , Luo Wen-yuan , Zhang Wei , Ming An-bo , Wu Shan-qi , Liu Bing-qi
Published: January 2019

The detection and evaluation of low energy impact damage of carbon fibre reinforced polymer (CFRP) laminate were investigated using vibrothermography. To this goal, four specimens were begun with low energy impact with different energies, followed by the detection using vibrothermography. The detection results show that the matrix crack is mainly located closer to the surface opposite to impact, while the delamination is mainly closer to the impact surface. Then, an iterative algorithm based on maximal entropy theory was proposed for thermal image segmentation and on this basis, the damaged area was determined. The obtained results show the damaged area increases with the increase of impact energy and the damaged area and impact energy may present an approximate linear relationship.
Improved Stresses Analysis of a Functionally Graded Beam under Prestressed CFRP Plate
Authors: Brairi Samir , Kerboua Bachir , Bensaid Ismail
Published: January 2019

In this paper, a new analytical solution is presented to predict the interfacial stresses of a functionally graded beam reinforced by a prestressed CFRP plate under thermo-mechanical load. A finite element (FE) analysis is also employed to validate the results of the analytical solution, the results from both models agreed very closely. Also, a parametric study is carried out in order to identify the effects of various material and geometrical properties on the magnitude of interfacial stresses. The presented results show that the interfacial stresses are highly concentrated at the end of the laminate, which can lead to a debonding at this location. Also, the material and geometrical properties have a significant impact on the magnitude of interfacial stresses. This new research approaches the practical reality of the structures in their environment by taking into consideration a combination of neglected terms by the other studies. Therefore, the results presented in this paper can serve as a benchmark for future analyses of functionally graded beams strengthened by prestressed Carbon fibre-rein-forced polymer (CFRP) plates and improve the rehabilitation, mechanical and corrosion resistance.
Prediction of the Damage Evolution of a C/SIC Composite Based on Grey Models
Authors: Wang Yiqiang , Cheng Laifei , Zhang Litong
Published: January 2019

The damage evolution of a C/SiC composite was investigated by repeated loading/unloading tests in terms of the reloading modulus and residual strain. Grey models were established for both the evolution of the damage factor and residual strain. The larger developmental coefficient of the evolution of the modulus suggests its competency to characterize the damage evolution relative to the residual strain. Excellent agreement between predictions and experimental results was obtained for both the grey models.
Interlaminar Fatigue Crack Propagation in Mode I of Carbon Fiber/PEEK Composites
Authors: Christopoulos G C , Paipetis S A
Published: January 2019

A study of the mode I interlaminar fracture toughness of a unidirectional carbon fibre reinforced thermoplastic matrix composite has been made using Double Cantilever Beam, DCB, specimens. Delamination growth per fatigue cycle, da/dN, was related with the maximum applied cyclic strain energy release rate, GIMAX, using a power law.
Influence of Zinc Iodide Penetrant on Damage Evolution in CFRP Laminates
Authors: Lafarie-Frenot M C , Henaff-Gardin C
Published: January 2019

This experimental study characterizes the influence, on the damage evolution, of ZnI2 impregnation under stress during creep of carbon/epoxy laminate. It appears that ZnI2 impregnation under stress very much accelerates the damage evolution, with the initiation and propagation of numerous cracks. The higher the applied stress is, the more important is the ZnI2 influence.
Exploration of Constants Independent of Material and Layup in Transverse Matrix Cracking of Cross-ply Laminate
Authors: Xu L-Y
Published: January 2019

Stiffness reduction caused by matrix crack in cross–ply laminates of CFRP, GFRP, KFRP can be predicted well by a shear–lag model assuming a constant of the crack open displacement index. Due to the existence of the saturation crack state (CDS), stiffness reduction has a low boundary, the minimum normalized longitudinal stiffness of the cracked plies is 0.3 instead of 0 used in current lamination theory on the behaviour prediction after FPF.
A Possible Way of Applying Schapery's Viscoelastic Fracture Model to Creep Crack Growth in Carbon-epoxy Composites
Authors: Delauménie V. , Chaoufi J. , Gamby D.
Published: January 2019

Schapery and Christensen's models of viscoelastic fracture have been adapted to describe the phenomenon of transverse cracking in composites. In a second stage, the application of both models to a known composite allowed to determine the size of the “failure zone”, which is one of key parameters in Schapery's model.
Damage Induced Anisotropy in Laminates
Authors: Dzenis Yu. A. , Joshi S. P.
Published: January 2019

A damage evolution model developed by the authors is utilized to study the effect of damage induced anisotropy on constitutive behavior and failure strength of laminates. It is shown that extension-shear coupling coefficients of the in-plane stiffness matrix radically change due to unequal damage accumulation in plies with opposite orientation under shear loading. This, in general, causes significant reduction in laminate shear strength. The angle-ply orientation and presence of zero degree plies in a laminate have a notable effect on damaged induced anisotropy.
Fatigue Damage of Composite/Composite Adhesively Bonded Joints
Authors: Roy A. , Gacougnolle J.L. , Petit J. , Gamby D.
Published: January 2019

In this experimental study, the fatigue damage of glass-polyester composite/composite adhesively bonded joints is investigated. The study shows that the damage consists of a main crack appearing in a stress concentration zone in the adherends which then grows in the laminate first layer in a mixed mode propagation stage to the final stage leading to the ultimate failure.
Microstructure Related Fracture Behavior of a Discontinuous Polymer-Polymer Microlayer Composite
Authors: Yuan Q. , Karger-Kocsis J. , Friedrich K. , Grosso M.
Published: January 2019

The fracture behavior of a discontinuous microlayer polymer-polymer composite was studied at −40 °C on notched Charpy specimens and unnotched plates in instrumented impact bending and falling weight impact tests, respectively. The microstructure of the specimens, containing discontinuous layers of modified polyamide (PA; Selar®, Du Pont), more or less uniformly stacked and well overlapping, in a high-density polyethylene (HDPE) matrix, was assessed by light microscopy. Failure mode of the microlayered specimens was studied by fractography. It was concluded that the in-plane impact response of this discontinuous microlayer composite is superior to the out-of-plane one. In addition, a fine and regular microstructure imparts to a high impact resistance.
Measurement of interfacial adhesion in carbon/ epoxy composite after plasma surface treatment on carbon fibers
Authors: Ahn H. S. , Schwartz P.
Published: January 2019

After gas plasma treatment with oxygen for 1 min or argon for 2 min at a power of 30 watts, scanning electron microscopy (SEM) showed changes in the surface topography of carbon fibers. Microbond tests showed improvement of the interfacial shear strength (IFSS) between AS4 carbon fibers and bisphenol A based (DGEBA) epoxy resin.
A Finite Element Failure Model for Notched Laminated Composites Loaded in Compression
Authors: Soutis C. , Tenchev R.
Published: January 2019

This paper describes a progressive damage failure model which is making an attempt to predict damage growth and ultimate compressive strength of notched laminates subjected to uniaxial compression. A non-linear finite element programme is developed to perform the ply-by-ply stress analysis and numerical results are compared with existing experimental data [1,2]; the agreement is acceptable.
The Effect of Na Salt on the Destabilization of YSZ Ceramic
Authors: Hongyuan Fang , Jiuhuai Zhang , China P R , Iwamoto Nobuya
Published: January 2019

The effects of NaCl and Nacl+Na2SO4 eutectic on ZrO2-Y2O3 ceramics at 1000°C was investigated. The weight changes and bend strength of the ceramics were measured. The X-ray diffraction analyses results showed that the NaCl coatings had a significant influence on the microstructure of YSZ ceramic at high temperature, as a consequence of destabilizing the cubic zirconia phase. Compared with NaCl, the influence of NaCl*Na2SO4 eutectic coating was weaker.
Treated Aramid Fibres as Reinforcement for Epoxies
Authors: Andreopoulos A. G. , Tarantili P. A.
Published: January 2019

Aramid fibres are chemically treated with methacryloyl chloride in order to improve their adhesion to epoxy resins. Original and modified fibres were characterised by FTIR spectroscopy, optical microscopy and tensile tests. The wettability of fibres was assessed by contact angle measurements. Also, composite specimens were prepared using epoxy resin as a matrix and their tensile characteristics were determined. The microscopic examination of the fracture surfaces of composite specimens tested in tension, shows improvement in adhesive bonding between the chloride treated fibres and the epoxy matrix.
Tensile Property Evaluation of Continuous Fibre MMC
Authors: Chen AS , Smith J , Bushby RS , Phillips MG , Scott VD
Published: January 2019

A tensile test method is described for continuous fibre metal matrix composites and used to evaluate the properties of aluminium alloy reinforced with Altex fibre. The composite, which was manufactured to a high quality using liquid-metal infiltration, was shown to possess high longitudinal modulus and strength and to have a transverse strength comparable with that of unreinforced alloy.
Study of Fatigue Internal Damage of Aluminum Alloy by Means of Caustics
Authors: Papadopoulos G.A. , Korovesis D.A.
Published: January 2019

The influence of the fatigue on the local internal Damage at crack tip area in a cracked plate of Aluminium alloy was studied by using the optical method of caustics. The variation of the modulus of elasticity and the Damage factor at the the crack-tip were estimated.
Determination of Stress Distribution in Fibre Bridged Cracks in Ceramic Matrix Composites
Authors: Bollet F. , Galiotis C. , Reece M. J.
Published: January 2019

Laser Raman Spectroscopy is being used to characterise interfacial properties and stress concentration in bridging fibres of a glass ceramic matrix composite. The preliminary results show that the stress distribution along fibres can be mapped. This technique will therefore assist the understanding of the fracture and fatigue behaviour of these materials.
Wettability of Copper Coated Carbon Fibers
Authors: Carotenuto G. , Gallo A. , Nicolais L.
Published: January 2019

The wetting kinetics of a solid surface by a molten metal decrease with increase of its roughness. The topography of the growing copper coating, produced on carbon fiber surface by electroplating from a sulphat bath, has been studied by scanning electron microscopy. The smoothes surface is produced after 200÷300 milliampere-hour of plating.
Fatigue Effect on the Dynamic Properties of Cfrp Composites
Authors: Vellios L. , Kostopoulos V. , Paipetis S. A.
Published: January 2019

Damage developing during fatigue of composite laminates affects both dynamic modulus of elasticity and damping coefficient of the material. It has been shown that the effect of fatigue on the damping coefficient is of particular importance. The damping variation could be used to characterise the damage state of the material, produced by fatigue. A model relating damage with damping was developed to correlate damage development to mechanical response. The damping coefficients of the composite of the fatigue test were measured at various stages, using the flexural free vibration of the test coupon hi cantilever configuration. The method was applied both in multidirectional and unidirectional laminates.
Constrained Transverse Cracking in Composite Laminates
Authors: Saha Reema , Talreja Ramesh
Published: January 2019

This paper reports an experimental study of transverse cracking in 90° plies of (±θ° /90°2)s laminates of graphite/epoxy. The constraint to this cracking process is varied by varying the angle θ to have the discrete values of 0°, 15°, 30° and 40°. The evolution of crack density and the associated stiffness changes of the laminates are studied. The crack densities are measured in tensile specimens at increasing stress levels by examining the edge replicas under an optical microscope and the continuity of these cracks between the specimen edges is ascertained by X-ray radiography. The stiffness changes are reported here and the stiffness-damage relationships are analyzed in a separate study.
Correlation between Interfacial Microstructure and Conditions of Bonding in Carbon Fibre-Copper Composites
Authors: Włosiński W.K. , Pietrzak K. , Kaliński D. , Olesińska W.
Published: January 2019

Carbon fibre reinforced copper matrix composites have been produced to provide materials with high thermal conductivity for use in semiconductors (diodes and thyristors) and electrical contacts. The problem of poor wettability of the carbon fibres by the copper matrix was overcome by admixing the matrix with zirconium which react with the carbon fibres to form carbides. The amount of carbides formed in the interface layer and, thus, the properties of the composite can be controlled by controlling the amount of the active element added, or by modifying appropriately the process parameters. This latter method has been examined in the present study. The experimental results have been verified by calculating and analysing the thermodynamic parameters of the process.
Dielectric Response during Cure of Particulate Composites of Epoxy Resin and Nickel Particles
Authors: Tsangaris G.M , Maistros G.M.
Published: January 2019

The cure process of particulate composites consisting of an epoxy resin and nickel particles, was monitored dielectrically. The inclusion of metal powder in the resin causes a delay in the cure process. It also adds considerable conductivity and after gelation interfacial polarization phenomena are evidenced in the low frequencies, because of the interfaces introduced by the metal particles.
Environmental Influences on the Bending Properties of Sisal Fiber Reinforced Polymer Composites
Authors: Selzer R.
Published: January 2019

This investigation deals with the effect of environmental influences on the mechanical properties of sisal fiber reinforced polymer composites. Dependencies between moisture, acid as well as lys attacks were determined and mechanical data of sisal fiber-polypropylene are evaluated. The results obtained led to the conclusion that the bending properties of sisal fiber-polypropylene composites are sensitive to environmental attack.
Interlaminar Fracture of Stitched GFRP Laminates
Authors: Li Rongzhi , Ye Lin , Mai Yiu-Wing
Published: January 2019

The mode I interlaminar fracture of Kevlar thread stitched GFRP laminates has been studied using double-cantilever-beam (DCB) tests. It was found that stitching density and patterns influence interlaminar fracture performance of composites mainly through the different failure mechanisms of stitch threads during crack propagation.
Mechanical Properties of Flexible Knitted Composites
Authors: de Haan J. , Peijs T.
Published: January 2019

This study investigates the influence of the matrix material and the degree of prestretch of a knitted fibre structure on the mechanical properties of knitted composites with low fibre volume fractions. By embedding a flexible textile structure in an elastomeric matrix, composite materials are obtained that combine an interesting stress-strain behaviour with extreme extensibility and relatively high levels of energy absorption. Although this study focuses on the influence of the degree of prestretch of the knitted structure on composite properties based on rubbery matrices, reference materials based on highly cross-linked epoxy resins were also studied.
Optimal Design by Genetic Algorithm for Maximum Fundamental Frequency of Laminated Shallow Shells
Authors: Narita Y , Itoh M , Zhao X
Published: January 2019

A genetic algorithm (GA) is applied to the optimization problem for maximizing the fundamental frequency of laminated shallow shells. A frequency formula is derived for the shallow shell supported by shear diaphrams, and is used in the GA optimization process. The advantage of using GA approach in the laminated shell problem is demonstrated.
Effect of Processing Residual Stresses on Stress-Strain Behavior of Brittle Matrix Composites
Authors: Giannakopoulou A. A. , Gdoutos E. E.
Published: January 2019

An analytical investigation of the effect of processing residual stresses on the longitudinal tensile behavior of unidirectional brittle matrix composites was undertaken. The study was based on a modified shear lag analysis. From the results of the investigation the dependence of the macroscopic stress-strain curve and the microscopic failure mechanisms including matrix cracking initiation and multiplication, and fiber debonding on the level of processing residual stresses was established.
Stiffness and Strength Anisotropy in the Tensile Response of Weft Knitted Fabric-Reinforced Peek- and Pet-Composites
Authors: Karger-Kocsis J. , Czigány T. , Gaál J. , Ostgathe M.
Published: January 2019

The mechanical response of weft knitted carbon (CF) and glass fibre (GF) fabric-reinforced thermoplastic composites with polyetheretherketone (PEEK) and polyethyleneterephthalate (PET) was studied by dynamic-mechanical thermal analysis (DMTA) and static tensile tests. A strong anisotropy was observed in both stiffness and strength when the specimens were loaded in wale (stronger) and course direction (weaker) of the knit, respectively. The anisotropy factor was estimated by considering the relation of the loop numbers in course and wale direction, that resulted in good agreement with the experimental data.
A Revised Shear-Lag Analysis of an Energy Model for Fiber-Matrix Debonding
Authors: Nairn John A. , Wagner H. Daniel
Published: January 2019

A shear-lag analysis based on energy is used to predict the amount of debonding that occurs when a fiber fragment breaks into two fragments. The shear-lag analysis reproduces all features of more sophisticated analyses. A drawback of the shear-lag analysis, however, is that it depends on an unknown parameter which can be expressed in terms of an effective fiber volume fraction. If the effective fiber volume fraction can be determined (by experiments or by advanced stress analyses), the shear-lag model can be used to interpret debonding experiments.