Interaction In Composite Materials Research Articles

On the role of curvature in the response of air-backed composites to hydrodynamic loading: An experimental study

Composite materials are increasingly utilized in high-performance naval structures, due to their superior properties over traditional materials like steel and aluminum. However, their widespread use is hindered by our limited understanding of their behavior when exposed to marine environments. One of the main loading conditions encountered during operations at sea is the hydrodynamic loading on the side in contact with water. Despite the practical significance of curved composite structures, the state-of-the-art on air-backed composites relies on the study of flat plates. Here, we use three-dimensional digital image correlation and planar particle image velocimetry to study the influence of curvature on the dynamic response of composite plates to hydrodynamic loading. Our findings reveal that curvature significantly influences both structural deformations and flow physics. The curved plate experiences localized vibrations with lower amplitude and higher frequency, caused by its increased stiffness. Additionally, the hydrodynamic pressure at the center of the plate decays faster in time for the curved configuration, highlighting the importance of curvature in shaping fluid–structure interactions. Our results advance the understanding of fluid–structure interactions in composite materials and highlight the importance of curvature in the design of resilient marine structures.

Influence of magnetic interactions in iron oxide nanoparticle polymer composites on magnetism and induction heating

Induction heating of composite materials is of great interest in fields such as controlled polymer curing or degradation, self-healing or contactless joining. Ferrimagnetic iron oxide nanoparticle (IONPs) are suitable candidates for a powder additive to provide this inductive heating functionality, while being low-cost, abundant and a well-studied material class. Varying IONP size, morphology or doping facilitates fine-tuning of their heating properties. However, the interactions of such IONP additives in material composites are often neglected and can significantly alter the induction heating mechanism. In this work, we systematically vary the IONP interactions in polydimethylsiloxane composite materials by integrating 1.) dispersed IONPs 2.) supraparticles of IONPs (micrometer-assemblies), and 3.) oven-dried hard agglomerated IONPs. Additionally, these three levels of interaction are investigated for three different IONPs types (dodecahedrally and octahedrally shaped, as well as cobalt-doped). In general, dispersed IONPs reveal a broader hysteresis and therefore a faster heating curve. We highlight that not only IONP characteristics (size, morphology, doping), but also excitation field strength and foremost IONP interactions in the composite materials are parameters that are interdependent regarding induction heating and need to be considered as such for optimization in an application-oriented scenario.

Morphology constraint of β-HMX in polymeric carbon nitrides towards hybrid energetic materials

The exploration of hybrid energetic materials is of great importance because of their enhanced performances and promising applications in aerospace exploration, military and civil technologies. Herein, a new type hybrid energetic material is prepared by the integration of energetic molecule HMX and polymeric carbon nitrides (PCNs). Two PCNs-HMX were prepared from melem and melem hydrazine by in-situ self-assembly on HMX with glyoxal, the complexes were named as MGP-HMX and MHGP-HMX, respectively. The planar structure and conjugated π-system of 2D-PCNs benefit the reduced sensitivities and help to control the polymorphism of HMX. The hybrid complexes MGP-HMX and MHGP-HMX demonstrate remarkably high thermal stabilities. An interesting morphology constraint effect of β-HMX is observed only for the hydrazone-linked MHGP, but not for the imine-linked MGP. The constraint effect blocks the solid–solid transition of HMX from high energetic β-phase to low energetic δ-phase. The key to constrain the solid–solid morphology transition in MHGP-HMX is furtherly investigated by visualization of the interaction in composite materials. The massive hydrogen bonds between NO2 groups of HMX and hydrazone moieties of MHGP and the squeezing of HMX in 2D layers account for the morphology constrain. The morphology constraint via PCNs provides a new strategy for the construction of new hybrid energetic materials with high thermostability and low sensitivity.

The Role of Interfacial Morphology in the Gas Transport Behavior of Nanocomposite Membranes: A Mathematical Modeling Approach

The presence of polymer–particle interactions in composite materials leads to the formation of interfacial layers with physical properties significantly different from those of the polymer matrix and fillers. Mathematical modeling of the interfacial morphology in mixed matrix membranes (MMMs) not only considerably depends on the assumed interface thickness, but also is related to the applied modeling algorithm. In the current study, a new algorithm is developed to estimate the interface thickness based on findings of molecular dynamics and Monte Carlo simulations in the literature as well as the size and the loading of the particles. Moreover, effective permeability of the MMMs is predicted with no need to evaluate the permeability of the particles and the type of interfacial morphology by only adjusting the reduced permeability factor in the range of −0.5 to 1. On the basis of the proposed modeling approach, characteristic parameters of encapsulated particles by interfacial layer, β and γ, can be simply ...

How effectively do carbon nanotube inclusions contribute to the electromagnetic performance of a composite material? Estimation criteria from microwave and terahertz measurements

Screening effect in finite-length carbon nanotubes (CNT) and their agglomerates hinders significantly the electromagnetic interaction in composite materials. Screening effect is strong in the microwave range, and it decreases with increasing frequency resulting in a strong frequency dependence of the effective conductivity of the composite. Since screening effect is rather small in the terahertz range, the effective conductivity in this range is determined directly by the intrinsic conductivity of the inclusions. The ratio of the microwave to terahertz effective conductivities was proposed as a parameter to estimate how effectively carbon nanotube inclusions contribute to the electromagnetic performance of composite materials in the microwave range. CNT film was considered as a material where maximal possible interaction of the CNTs with EM field occurs. Single-walled CNT films and CNT-based composite materials, as well as hybrid film comprising mixtures of WS2 nanotubes and CNTs were fabricated and measured in the microwave and terahertz ranges. The electromagnetic field interaction with the inclusions has been estimated for all the samples fabricated.

Three Phase Boundary Enhancement in SOFC Anodes by Applying Laser Drilling Technique

Laser drilling is one of the promising techniques to modify layers, but the interaction of composite materials with the laser radiation is non-trivial and hardly predictable. In this work, the experimental study of laser processing, that was applied to enhance porosity and thereby the length of three-phase boundary of plasma-sprayed YSZ-NiO-Ni cermet layer, is presented. For a better understanding of radiation interaction with composite materials the drilling was accomplished with different laser irradiation doses (1.57–4.2×10 5 J/cm 2 ) with two different laser systems. The diameter and shape of the laser drilled holes were analyzed with a scanning electron microscope (SEM) while changes of the elemental composition of the spatter versus conditions of irradiation were defined by energy dispersive X-ray analysis (EDX). It has been found that geometrical dimensions of the drilled holes as well as composition of the spatter vary non-monotonously with the laser irradiation dose. The threshold values of the laser irradiation dose for the optimal diameter of holes are reported.

Melt Flow Instabilities of Wood Polymer Composites

Melt flow instabilities during extrusion of wood polymer composites (WPC) containing 30–60 wt% wood flour (WF) have been investigated. The research emphasized elucidation of the extrudate surface tearing mechanism and its relation to wall slip. This interesting phenomenon has been known in the WPC industry for years; however, it has not received much research interest. It was observed that increasing the wood flour loading up to 50 wt% aggravated the surface tearing; however, addition of 60 wt% wood flour completely eliminated the surface defect due to strong wall slip and plug flow. It was also found that addition of lubricants and increasing the shear rate significantly improved the surface appearance of the filled compounds. Molecular weight and molecular weight distribution of the polymer matrix influence the melt flow properties of the composites. The significance of the entrance pressure measurement and its usefulness for quantitative assessment of filler–matrix interactions in composite materials is also demonstrated in this paper.

Atomic-scale scanning tunneling microscopy study of plasma-oxidized ultrahigh-modulus carbon fiber surfaces

In the present work, scanning tunneling microscopy (STM) was employed to study the surface modification of ultrahigh modulus carbon fibers at the atomic level by oxygen plasma. As detected by STM, the distinctive feature of the fresh, untreated surface was the general presence of atomic-scale arrangements in different degrees of order (from atomic-sized spots without a clearly ordered disposition to triangular patterns identical to those typical of perfect graphite). Following fiber exposure to the plasma, the STM images showed evidence of the abstraction of carbon atoms from random locations on the fiber surface, giving rise to the development of defects (i.e., structural disorder), which in turn were the places where oxygen could be introduced during and after the plasma etching. It was observed that the most effective treatments in terms of extent of surface structural modification (disordering) and uniform introduction of oxygen were those carried out for just a few ( ∼ 3) minutes. Considerably shorter exposures failed to provide a homogeneous modification and many locations on the fiber surface remained unaltered, retaining their original atomic-scale order, whereas longer treatments did not bring about further structural changes to the surface and only led to fiber consumption. These results are consistent with previous X-ray photoelectron spectroscopy measurements on these fibers and provide an atomic-level understanding of the saturation effect observed in the surface oxygen concentration of this and other types of carbon fibers with plasma oxidation. Such understanding may also prove helpful for the accurate control and optimization of fiber–matrix interaction in composite materials.

The effect of interphase toughness on fibre/fibre interaction in graphite/epoxy composites: an experimental and modelling study

Fibre/fibre interaction in composite materials is a very important micromechanical phenomenon that dictates the composite mechanical behaviour especially the toughness and failure process. A number of models have been developed to predict the fibre/fibre interaction in composite materials, but none of the existing models has considered the effect of interphase toughness on fibre/fibre interaction. In this study, micro-Raman spectroscopy (MRS), with the ability to measure strain in graphite fibres with a spatial resolution of 2 µm, was used to measure fibre/fibre interaction in graphite/epoxy model composites with three different interphases. An energy-based model was used to calculate the strain energy release rate (Gi) for the three interphases used in this study. The three interphases, unsized, sized, and PMMA coated, yielded strain energy release rates of 40, 30, and 10 J m−2 respectively. Using the values calculated for strain energy release rate of the interphase and interfacial crack length, the energy-based model predicated stress concentration factor values in agreement with those experimentally measured. Copyright © 1999 John Wiley & Sons, Ltd.

Composite technology in load-bearing orthopaedic implants

Composite materials have been widely promoted as possible orthopaedic biomaterials but to date have found few successful commercial applications, due to the many challenging problems presented by their design, fabrication and testing. The range of possible composite biomaterials is reviewed, together with the possible methods of fabrication and the limitations that these place on the design of composite components. The use of composite materials allows many new design possibilities, but this freedom of design requires a clearer understanding of the objectives and constraints on the design process. The testing of composite components also presents many challenging problems, which are not adequately addressed by existing standards developed for testing conventional monolithic materials. The interaction of composite materials with the body is more complex than that of the component materials, and the prediction of their long-term mechanical performance also presents many intractable difficulties. However, despite these challenges composite materials are likely to prove invaluable in the future development of orthopaedics.

“Fundamental” and “practical” adhesion in polymer-fiber systems

The relationship between adhesion and bond strength in thin fiber-polymer matrix systems was studied. Adhesive interaction in composite materials was analyzed within the scope of thermodynamic and molecular-kinetic theories of adhesion. Methods based on wetting are shown to give poor estimation of the work of adhesion in fiber-polymer systems, which is due to their low sensibility to donor-acceptor interactions taking place at the interface. Important information about the acidity and basicity of contacting surfaces can be obtained by using inverse gas chromatography to investigate the thermodynamics of adsorption. The calculation of the work of adhesion including acid-base interactions shows the best agreement with the bond strength in the same systems. The local (ultimate) interfacial shear strength is proposed to characterize the quality of fiber-matrix bonding. Analysis of the relationship between the work of adhesion and adhesive pressure for various systems allowed us to differentiate the dispersive and acid-base components of the local bond strength as well as to estimate distances characteristic of these two

Molecular interaction in composite materials based on polycaproamide and epoxy resins

Molecular interaction in composite materials based on polycaproamide and epoxy resins

Comp'88: Phase interaction in composite materials: to be held at The University of Patras, Patras 260 01, Greece 22–27 August 1988

Comp'88: Phase interaction in composite materials: to be held at The University of Patras, Patras 260 01, Greece 22–27 August 1988

A Comparative Study of Crack/Crack Interaction in Composite Materials Using Macro and Micromechanical Models

The effects of interaction between crack-like defects in fiber reinforced composite materials on the local stress concentrations in their neighbourhoods are theoretically investigated from the macro and micro and micromechanical points of view. The most simple models consisting of homogeneous and heterogeneous anisotropic elastic plates with two collinear or parallel cracks are assumed, and the mathematical formulations are made in terms of the Cauchy-type singular integral equations of the first kind by the methods of harmonic-type stress functions and Fourier transforms. Numerical calculations are carried out for the stress intensity factors, and the results thus obtained from these models are compared with each other.

A comparative study of crack/crack interaction in composite materials using macro and micromechanical models.

The effects of interaction between crack-like defects in fiber reinforced composite materials on the local stress concentrations in their neighbourhoods are theoretically investigated from the macro and micromechanical points of view. The most simple models consisting of homogeneous and heterogeneous anisotropic elastic plates with two colinear or parallel cracks are used. Plane stress and plane strain conditions are assumed, and the mathematical formulations are made in terms of the Cauchy-type singular integral equations of the first kind through the methods of harmonic-type stress functions and Fourier transforms. Numerical calculations are carried out for the stress intensity factors, and the results thus obtained from these models are campared to each other.

Physicochemical interactions in composite materials of aluminum alloys reinforced with steel wire

1. The kinetics of growth of the transition zone in filament-reinforced materials of Al-EP322 and Al-Zn-Mg alloy-EP322 was studied by means of metallographic analysis at 475–600°. 2. Interdiffusion of elements between the matrix and the filament, with the development of intermetallic layer, occurs during heat treatment of these composite materials. The activation energy for growth of the intermetallic layer was calculated for the Al-EP322 composite. 3. Comparison of the growth rates of the transition zone showed that the growth rate is higher in the composite with an Al-Zn-Mg matrix than in the composite with a matrix of pure aluminum.