Homogenization Step Research Articles

Effect of the thermal annealing and the nominal composition in the elemental distribution of InxAl1-xAsySb1-y for triple junction solar cells

In this work, the effect of thermal annealing under As overpressure in the composition distribution of In8Al42As34.5Sb15.5 layers, lattice matched to InP for triple junction solar cells, is analysed by APT. We have found that in the as-grown sample there is a statistically significant number of In-rich regions with size ∼10 Å. Upon annealing, the composition gradient from the centre of the In-rich regions towards the homogeneous region is reduced, and the size of the enriched regions increases up to ∼35 Å. This points to In out-diffusion as an initial step of the material homogenization, which would explain previous results of PL emission. Additionally, the comparison of the obtained results with previous analysis by the authors has shown that the increase in the In content of InAlAsSb epitaxial layers has a strong effect on the composition distribution of the material, stimulating deviations from the random alloy in both the group III and the group V sub-lattices.

Influence of Homogenization Time and Speed on Rheological and Volatile Composition in Olive-Based Pâtés.

The influence of the homogenization time and speed on rheological and volatile composition in olive-based pâtés was studied. Five experimental trials were performed applying different combinations of time and speed homogenization: 1, 3, and 5 min at 12,000 rpm and 4000, 8000, and 12,000 rpm at 5 min. The obtained results showed that the processing parameters of the homogenization step significantly influenced the rheological and sensory properties of olive-based pâtés. Both time and speed influenced the rheological properties of the product. The increase of homogenization time and speed determined a significant reduction of hardness and syneresis. As regards color indices, significantly higher L* values were obtained when intermediate time and speed conditions were applied, whereas a* and b* indices showed a not univocal behavior. Both time and speed variables also influenced the volatile fraction of the pâtés (higher homogenization speed and time corresponded to higher terpenes and aldehydes).

Multi-step homogenization in the Mori-Tanaka-Benveniste theory

Micromechanical schemes homogenizing elastic properties as well as thermal and electrical conductivities of heterogeneous materials are most often developed as one-step procedures when all inhomogeneities are drawn into calculations at once, leaving no possibility for a multi-step approach. However, in practice, the multi-step homogenization is involved more often than expected, sometimes not on purpose. The reason is unknown microstructure of composite constituents while micromechanical schemes typically require their phases to be homogeneous. Thereby, constituents’ properties, submitted to schemes, are effective, not intrinsic, contrary to schemes’ requirements. This implicitly introduces preliminary homogenization steps to provide these effective properties, and the actual scheme considered corresponds to the last step of a multi-step homogenization process. However, our knowledge on applicability of multi-step homogenization techniques is more limited in comparison with the well-studied one-step schemes. Our study explores differences among one-, two-, and multi-step procedures in the Mori-Tanaka-Benveniste theory. For two-phase unidirectional composites, two- and one-step procedures differ by change in effective field related to change in concentration tensors. For porosity, two- and one-step homogenizations become identical if Eshelby tensor is multiplied by a scalar coefficient depending on volume fractions. Finally, applicability of the two-step procedure is verified for anisotropic three-phase composites.

Homogenizing Estimates of Heritability Among SOLAR-Eclipse, OpenMx, APACE, and FPHI Software Packages in Neuroimaging Data.

Imaging genetic analyses use heritability calculations to measure the fraction of phenotypic variance attributable to additive genetic factors. We tested the agreement between heritability estimates provided by four methods that are used for heritability estimates in neuroimaging traits. SOLAR-Eclipse and OpenMx use iterative maximum likelihood estimation (MLE) methods. Accelerated Permutation inference for ACE (APACE) and fast permutation heritability inference (FPHI), employ fast, non-iterative approximation-based methods. We performed this evaluation in a simulated twin-sibling pedigree and phenotypes and in diffusion tensor imaging (DTI) data from three twin-sibling cohorts, the human connectome project (HCP), netherlands twin register (NTR) and BrainSCALE projects provided as a part of the enhancing neuro imaging genetics analysis (ENIGMA) consortium. We observed that heritability estimate may differ depending on the underlying method and dataset. The heritability estimates from the two MLE approaches provided excellent agreement in both simulated and imaging data. The heritability estimates for two approximation approaches showed reduced heritability estimates in datasets with deviations from data normality. We propose a data homogenization approach (implemented in solar-eclipse; www.solar-eclipse-genetics.org) to improve the convergence of heritability estimates across different methods. The homogenization steps include consistent regression of any nuisance covariates and enforcing normality on the trait data using inverse Gaussian transformation. Under these conditions, the heritability estimates for simulated and DTI phenotypes produced converging heritability estimates regardless of the method. Thus, using these simple suggestions may help new heritability studies to provide outcomes that are comparable regardless of software package.

A two-step multiscale model to predict early age strength development of cementitious composites considering competing fracture mechanisms

Abstract A finite element-based multiscale model is employed to examine the early-age mechanical behavior of cementitious composites under a mode-I loading condition. The mechanical response of early-age mortar and concrete are influenced by the time-dependent development of mechanical properties of the cement paste as well as the mechanical and morphological properties of the aggregate phase. A competing mechanism exists in the fracture process (i.e., crack propagation) of the aggregate and cement paste phases. This paper investigates the distinct role played by the properties of each phase. This paper addresses the problem through a two-step homogenization approach that first starts at the meso-level of the mortar, where the fine aggregates are embedded within the cement paste. The second step considers the homogenization of concrete composed of the mortar matrix resulting from the first homogenization step, and coarse aggregate particles. For the purpose of computational homogenization, the continuous scheme for bulk modeling combined with the discontinuous scheme for modeling the transition of mesoscopic diffusive damage to macro-crack are employed. Inter- and intra- phase cohesive zone elements are utilized to represent the fracture process. The results indicate the relative significance of elastic and cohesive properties of composite constituents for the development of tensile stiffness and strength, damage evolution, and macro-crack patterns. A competing mechanism was observed for early-age cracking of the cementitious composites. When the tensile strength of the cement paste is lower than the tensile strength of aggregate phase, the crack propagates across the paste. When the tensile strength of the cement paste exceeds that of the aggregate, the cracks begin to deflect and propagate through the aggregates. As such, a critical degree of hydration (associated with a certain time) exists below which the cement paste phase is weaker than aggregate phase at the onset of hydration. This has implications on the inference of kinetic based parameters from mechanical testing (e.g., activation energy). Our results show a promising quantitative agreement with experimental observations.

Fine Cellulosic Materials Produced from Chemical Pulp: the Combined Effect of Morphology and Rate of Addition on Paper Properties.

Among bio-based reinforcement additives for paper existing on the market, microfibrillated cellulose (MFC) turned out to be a promising material, showing outstanding potential in composites science. Its relevance in papermaking as a new family of paper components was suggested more recently. There remains a number of constraints limiting the promotion of their use in papermaking, mostly related to their high cost and effect on dewatering resistance. Also, contrasting results reported in the literature suggest that the effect of fibrillation rate and quantity of such cellulosic additives in a furnish on the technological paper properties needs further research. The purpose of this study is to produce and characterize different MFC-like fine fibrous materials of varying particle size and degree of fibrillation from the same batch of pulp through mechanical treatment or fractionation. The effect of the thus obtained fine fibrous materials on paper properties is evaluated with respect to their concentration within a fiber furnish. We compared: (i) a mixture of primary and secondary fines isolated from the pulp by means of a purpose-built laboratory pressure screen; (ii) MFC-like fine fibrous materials of increasingly fibrillar character obtained by refining and subsequent steps of high-pressure homogenization. The morphology of the different materials was first characterized using flow cell based and microscopic techniques. The thus obtained materials were then applied in handsheet forming in blends of different proportions to evaluate their influence on paper properties. The results of these experiments indicate that all these products lead to a substantial decrease in air permeability and to improved mechanical properties already at low concentration, independent of the type and morphological character of the added fine cellulosic material. At higher addition rates, only highly fibrillated materials allowed a further considerable increase in tensile and z-strength. These observations should help to allow a more targeted application of this new generation of materials in papermaking, depending on the desired application.

Structural and chemical homogeneity of chalcogenide glass prepared by melt-rocking.

The chemical and structural homogeneity of selenide glasses produced by mechanical homogenization of the melt in a rocking furnace is investigated by Raman and Energy Dispersive Spectroscopy (EDS). Both techniques demonstrate that the glass is macroscopically homogeneous along the entire length of a 6 cm rod. EDS imaging performed over four orders of magnitude in scale further confirms that the glass is homogeneous down to the sub-micron scale. An estimate of the diffusion coefficient from experimental viscosity data shows that the diffusion length is far larger than the resolution of EDS and therefore confirms that the glass is homogeneous at any length scale. In order to investigate a systematic mismatch in physical properties reported in the literature for glasses produced by extended static homogenization, two germanium selenide samples are produced under the same conditions except for the homogenization step: one in a rocking furnace for 10 h and the other in a static furnace for 192 h. No difference in physical properties is found between the two glasses. The properties of an ultra-high purity glass are also found to be identical. The origin of the systematic deviation reported in the literature for germanium selenide glasses is therefore still unknown, but the present results demonstrate that homogeneity or dryness does not have a significant contribution in contrast to previous suggestions. The implications of glass homogeneity for technological applications and industrial production are discussed.

An adaptive FE2 method for the thermomechanical behaviour of a SMA‐Fiber matrix composite

AbstractThis contribution deals with the multiscale analysis of a reinforced matrix with shape‐memory‐alloys (SMA). The complicated micro‐structure permits a full discretized macro‐structure, due to that an FE2 approach is used. Unlike classic materials, the SMA has more complex behavior with a high‐temperature dependency in the loading and unloading case. The micro‐structure of the macroscopic problem consists of a linear‐elastic matrix and a random fiber distribution. The stress response of the composite depends non‐linearly on the deformation, the fiber orientation and the temperature. Due to the non‐linear behavior of the fiber a nested homogenized is employed at each integration point. This results in the so‐called FE2 method. One disadvantage of the FE2 method is the high computational effort by solving the boundary value problem (BVP) in every integration point and every iteration step. This motivates the present work to introduce an indicator, which determines whether an accompanying homogenization is needed. Due to the temperature dependency, on the macro‐scale, a coupled thermo‐mechanical problem is solved. In the first homogenization step, the BVP of the RVE is solved with Neumann Boundary conditions. This leads to an overestimation of the strains. The SMA will remain linear elastic until the phase transition condition is reached. The formulation is similar to the classical yield condition of elasto‐plastic materials, however, here a strain instead a stress creteria is used. From the phase transition condition, the temperature dependent indicator is defined and formulated as a limit strain for the linear behavior of the SMA‐fibers. The accompanying homogenization is firstly needed when the limit strain is reached.

Effects of Si and Fe micro-additions on the aging response of a dilute Al-0.08Zr-0.08Hf-0.045Er at.% alloy

The precipitation behavior of an Al-0.08Zr-0.08Hf-0.045Er at.% alloy with micro-additions of Si and/or Fe was investigated using microhardness and electrical conductivity measurements in conjunction with scanning electron microscopy and atom-probe tomography. Hardening is achieved through the formation of a high number density (~1023 m−3) of coarsening-resistant, nanoscale L12 trialuminide precipitates containing Zr, Hf, Er, and Si. Simultaneous additions of 300 at. ppm Si and 400 at. ppm Fe produce an alloy with the fastest precipitation kinetics and highest microhardness after homogenization at 640 °C for 24 h followed by 90 days aging at 350 °C, due to: (i) scavenging of Er by Fe in the form of primary precipitates, thus reducing Er-stimulated precipitation of coarse Zr- and Hf-rich precipitates during homogenization; and (ii) the accelerating effects of Si on the precipitation kinetics of the nanometric L12 trialuminide. Removal of the homogenization step results in accelerated precipitation kinetics during aging due to an increased supersaturation of L12-forming elements, Zr, Hf, and Er. During isothermal aging of a non-homogenized Al-0.08Zr-0.08Hf-0.045Er-0.03Si-0.04Fe (at.%) alloy at 400 °C, a peak microhardness of 500 MPa is maintained for up to 90 days. Atom-probe tomography displays a high number density of nanometric L12 precipitates with an Er-rich core and homogeneously distributed Zr and Hf, with Hf concentrations ~1.5 times higher at the matrix/nanoprecipitate heterophase interface than in the core (~5 vs. ~3.5 at.%). The presence of Hf in the nanoprecipitates does not, however, affect their precipitation kinetics or coarsening resistance.

Proton radiography with a commercial range telescope detector using dedicated post processing methods

Proton transmission imaging uses protons with high enough energy to fully traverse the phantom/patient and to be captured in a suitable detector placed behind it. The measured residual energy or residual range provide a direct estimate of the water equivalent thickness (WET) of the image volume. Requirements for proton imaging to be exploitable in clinical practice include: sufficient WET accuracy and integrability into the treatment room and the clinical workflow, as well as an acceptably low dose to the patient and a sufficient spatial resolution. In this work, we report on experiments performed at the Institut Curie—Proton therapy center in Orsay (IC-CPO), France, using a commercial range telescope commonly employed for quality assurance measurements. The purpose was to keep the experimental set-up as simple as possible and to achieve nonetheless high WET accuracy radiographies by developing and applying dedicated post processing methods. We explain these methods in detail and discuss their performance. We assess the WET accuracy based on two different reference phantoms: a CIRS electron density phantom with tissue equivalent inserts and a homogeneous step phantom. We find an agreement between the measured and the reference WET values of 0.2–0.5 mm. The lowest investigated dose was 10 mGy per acquisition. It could be lowered by modifying the irradiation plan and lowering the beam current, though the latter would impose slight optimisations of the detector hardware. Our work suggests that proton radiographies with good WET accuracy can be obtained with a reasonable experimental effort that would facilitate integration into clinical routine.

Detecting and typing target DNA with a novel CRISPR-typing PCR (ctPCR) technique

This study develops a new method for detecting and typing the interested DNAs based on CRISPR, which was named as ctPCR3.0, representing CRISPR- or Cas9/sgRNA-typing PCR, version 3.0. This technique detects target DNA in just one homogeneous step: quantitative PCR (qPCR) amplifying the Cas9/sgRNA-cleaved DNA samples. By directly adding Cas9 and sgRNA into the qPCR reaction and giving an additional isothermal incubation before qPCR program, the target DNA can be homogeneously detected in as few as 2 h. Without opening the detecting tube in the whole detection process, ctPCR3.0 can be used to detect target DNA as the traditional qPCR detection. The technique was fully verified by detecting the cloned HPV L1 genes of 10 high-risk human papillomavirus (HPV) subtypes. The technique also successfully detected the L1 and E6-E7 genes of two highest-risk HPVs, HPV16 and HPV18, in the genomic DNA of two HPV-positive cervical carcinoma cells, HeLa and SiHa. Finally, the ctPCR3.0 method was validated by successfully detecting HPVs in many clinical samples. By performing these detections, this study thus provides a new CRISPR-based DNA detection and typing platform and a ready-to-use HPV clinical detection technique. The platform has wide application in clinical diagnosis.

Validated HPLC-MS/MS method for quantification of ethylmethylhydroxypyridine succinate in rat brain and its application to a pharmacokinetic study

2-ethyl-6-methyl-3-hydroxypyridine (EMHP) succinate is the original antioxidant and antihypoxic drug commonly prescribed in Russia. The objective of this study was to develop a rapid, simple and sensitive high-performance liquid chromatography–tandem mass spectrometry (HPLC-MS/MS) method for EMHP quantitation in rat brain tissue with the use of a bead beating homogenizer. The comparison between two approaches to brain tissue preparation was performed, when spiking the blank brain tissue with EMHP reference standard and internal standard (IS) before and after homogenization step. Chromatographic separation was achieved using Zorbax Eclipse Plus C18 column (1.8 μm, 2.1 × 50 mm) and elution was performed with the mobile phase, consisting of 10 mM of ammonium formate aqueous solution with 0.1% formic acid as solvent A and 0.1% formic acid in methanol as solvent B [44%(А):56%(В), v/v]. Flow rate was 0.4 mL/min and the total run time for each sample analysis was 2.0 min. EMHP and amantadine, IS of this study, were analyzed in positive ionization mode. Ion transitions of m/z 138.0 → 123.0 for EMHP and m/z 152.0 → 135.0 for amantadine were selected in multiple reaction monitoring mode. The developed method for EMHP determination in rat brain samples was validated for selectivity, linearity, accuracy, precision, matrix effects, and stability. The lower and upper limits of quantification were determined to be 1 and 1500 ng/g, respectively. The developed and validated HPLC-MS/MS method was successfully applied to determine EMHP concentrations in rat brain tissue following the intraperitoneal administration at a dose of 3.4 mg/kg.

Formation of Lignin Nanoparticles by Combining Organosolv Pretreatment of Birch Biomass and Homogenization Processes.

Valorization of lignocellulosic biomass into a biorefinery scheme requires the use of all biomass components; in this, the lignin fraction is often underutilized. Conversion of lignin to nanoparticles is an attractive solution. Here, we investigated the effect of different lignin isolation processes and a post-treatment homogenization step on particle formation. Lignin was isolated from birch chips by using two organosolv processes, traditional organosolv (OS) and hybrid organosolv-steam explosion (HOS-SE) at various ethanol contents. For post-treatment, lignin was homogenized at 500 bar using different ethanol:water ratios. Isolation of lignin with OS resulted in unshaped lignin particles, whereas after HOS-SE, lignin micro-particles were formed directly. Addition of an acidic catalyst during HOS-SE had a negative impact on the particle formation, and the optimal ethanol content was 50–60% v/v. Homogenization had a positive effect as it transformed initially unshaped lignin into spherical nanoparticles and reduced the size of the micro-particles isolated by HOS-SE. Ethanol content during homogenization affected the size of the particles, with the optimal results obtained at 75% v/v. We demonstrate that organosolv lignin can be used as an excellent starting material for nanoparticle preparation, with a simple method without the need for extensive chemical modification. It was also demonstrated that tuning of the operational parameters results in nanoparticles of smaller size and with better size homogeneity.

Extracellular matrix scaffold and hydrogel derived from decellularized and delipidized human pancreas

Extracellular matrix (ECM) plays an important developmental role by regulating cell behaviour through structural and biochemical stimulation. Tissue-specific ECM, attained through decellularization, has been proposed in several strategies for tissue and organ replacement. Decellularization of animal pancreata has been reported, but the same methods applied to human pancreas are less effective due to higher lipid content. Moreover, ECM-derived hydrogels can be obtained from many decellularized tissues, but methods have not been reported to obtain human pancreas-derived hydrogel. Using novel decellularization methods with human pancreas we produced an acellular, 3D biological scaffold (hP-ECM) and hydrogel (hP-HG) amenable to tissue culture, transplantation and proteomic applications. The inclusion of a homogenization step in the decellularization protocol significantly improved lipid removal and gelation capability of the resulting ECM, which was capable of gelation at 37 °C in vitro and in vivo, and is cytocompatible with a variety of cell types and islet-like tissues in vitro. Overall, this study demonstrates the characterisation of a novel protocol for the decellularization and delipidization of human pancreatic tissue for the production of acellular ECM and ECM hydrogel suitable for cell culture and transplantation applications. We also report a list of 120 proteins present within the human pancreatic matrisome.

Effect of Processing on Bioactive Compounds, Physicochemical and Rheological Characteristics of Juçara, Banana and Strawberry Smoothie.

This study aimed to evaluate the effect of processing steps on bioactive compounds and physicochemical and rheological characteristics of a juçara, banana and strawberry smoothie. The product was obtained by mixing the pulps of these fruits in previously defined proportions. The mixture was standardized in a pilot disintegrator, homogenized at 60 MPa in continuous mode and pasteurized at 90 °C for 35 s. The homogenization step increased the concentration of cyanidin-3-O-glucoside and cyanidin-3-O-rutinoside, major anthocyanins in the smoothie. However, these anthocyanins, as well as perlagonidin-3-O-glucoside, have been reduced (p<0.05) after the pasteurization step. The pasteurization also affected the instrumental color of the smoothie, expressed by Hue angle (p<0.05). Regarding to the rheological behavior, the smoothie, in all processing steps, presented a non-Newtonian fluid behavior with pseudoplastic characteristics (n<1). After homogenization, the smoothie became more fluid and homogeneous. Thus, despite the negative impact of pasteurization on the smoothie's color, the pasteurized product preserves the bioactive compounds such as flavonoids and phenolic acids that are of great importance to human health. Furthermore, the development of this product contributes to add value to the juçara agro-chain and Atlantic Forest preservation.

Ultrasound-assisted extraction based on QuEChERS of pesticide residues in honeybees and determination by LC-MS/MS and GC-MS/MS.

In this work, 260 pesticide residues, including insecticides, acaricides, fungicides, and herbicides, were extracted from honeybees using the QuEChERS methodology modified by applying an ultrasonic probe, which avoided the homogenization step and reduced the extraction time. Gas and liquid chromatography, both coupled to triple-quadrupole mass spectrometry, allowed the determination of the pesticide residues extracted from the samples. The optimization of the main ultrasonic conditions (sonication amplitude, number of cycles, and time of each cycle) was performed using a Box-Behnken experimental design involving 15 experimental samples. The results obtained with this approach showed that the recoveries were not affected by these experimental parameters for 95 pesticide residues whereas the sonication amplitude was the main factor affecting the recoveries of 107 pesticide residues. The extraction time and the number of cycles affected four and one pesticide residues, respectively. The effectiveness of the ultrasonic-assisted extraction without homogenization of the honeybee samples compared favorably with that for the conventional QuEChERS methodology applied to the same previously homogenized samples. The proposed methodology was validated according to the SANTE/11945/2015 guidelines, with a 5μg/kg limit of quantitation. Recoveries between 70 and 120% and relative standard deviations lower than 20% were obtained for most analytes. Thirty honeybee samples taken from Spanish apiaries were analyzed using this new methodology. The results revealed the presence of 30 different pesticide residues in the honeybee samples, the highest concentration levels corresponding to certain insecticides/acaricides used by beekeepers to control Varroa destructor. Permethrin, thiabendazole, carbendazim, and coumaphos were the most frequently detected pesticide residues in the selected samples.

Multiscale modeling of viscoelastic behaviors of textile composites

Mechanics of Structure Genome (MSG) is extended to provide a new two-step homogenization approach to predict the viscoelastic behaviors of textile composites. The first homogenization step (micro-homogenization) deals with determining the viscoelastic properties of yarns from fibers (assumed to be linear elastic) and matrix (assumed to be linear viscoelastic) using the MSG solid model. In the second homogenization step (macro-homogenization), the viscoelastic behaviors of textile composites are computed from the homogenized yarns and matrix properties using the MSG plate model. Representative volume element (RVE) analysis using a commercial finite element package at micro-scale is conducted to verify the accuracy of MSG micro-homogenization. The viscoelastic behaviors of textile composites at macro-scale using the MSG plate model are validated using experimental data. All the results are in good agreements. The proposed approach is applied to several commonly used woven composites to study the effects of different weave patterns on the viscoelastic behaviors.

Influence of primary homogenization step on microfluidized emulsions formulated with thyme oil and Appyclean 6548

This contribution deals with the development of emulsions formulated using thyme essential oil and a new biomass-derived surfactant. In addition, this work extends our knowledge concerning the factors that can influence stability and droplet size distributions of microfluidized emulsions, such as the geometry of the rotor–stator used and the homogenization rate in the primary homogenization. Stable thyme oil-in-water emulsions (30wt%) containing submicron droplets were formed. Interestingly, laser diffraction results reveal that mean droplet sizes are mainly controlled by homogenization rates and polydispersity by the rotor–stator geometry used in the first step of homogenization. In addition, higher droplet sizes for pre-emulsions seem to be a key factor in order to reduce both the degree of recoalescence and the size of the droplets in the second homogenization step. Furthermore, higher droplet sizes in the pre-emulsion favour higher physical stability of the final emulsions. Finally, this research highlights the importance of controlling primary homogenization conditions for the physical stability of microfluidized emulsions that contain natural ingredients.

Effect of three-step homogenization on microstructure and properties of 7N01 aluminum alloys

Abstract The effect of different homogenization treatments on the microstructure and properties of the 7N01 aluminum alloy was investigated using hardness measurements, electrical conductivity measurements, tensile and slow strain rate tests, electron probe microanalysis, optical microscopy, scanning electron microscopy, and transmission electron microscopy. The results revealed that three-step homogenization improved the uniformity of Zr distribution by eliminating segregation of the main alloying elements. During the second homogenization step at 350 °C for 10 h, coarse and strip-like equilibrium η phases formed which assisted the nucleation of Al3Zr dispersoids and reduced the width of the precipitate-free zone of A13Zr dispersoids. As a result, coarse recrystallization was greatly reduced after homogenization at 200 °C, 2 h + 350 °C, 10 h + 470 °C, 12 h, which contributed to improving the overall properties of the 7N01 aluminum alloys.

Two-step hierarchical micromechanics model of partially saturated porous composites doped with ellipsoidal particles with interface effects

Abstract Recent advances in the manufacture of micro- and nano-composites have made it possible to produce new multifunctional materials. However, the development of theoretical models that assist their design still remains an open research issue. This paper presents a two-step hierarchical micromechanics approach for the mechanical homogenization of particle-reinforced porous composites, including particle/matrix interfacial bonding and porosity saturation effects. Firstly, the particle-reinforced matrix is homogenized by means of a double-inclusion approach. The interfacial bonding effect is accounted for by both compliant and hard interphases surrounding the particles. Secondly, another homogenization step is conducted by considering the particle-reinforced composite as a homogeneous matrix and voids as embedded inclusions. Pores saturation is also taken into account by means of homogeneous equivalent pores. Comparative analyses against experimental data are presented to demonstrate the effectiveness of the present approach, followed by detailed parametric analyses to illustrate the influence of the major micromechanical variables, including interphase thickness and stiffness, filler aspect ratio, porosity and saturation degree.