Transverse Properties Research Articles

The existence of real nine-dimensional manifolds which include classical one-parameter families of triply periodic minimal surfaces

Triply periodic minimal surfaces have been studied in many fields of natural science, and in particular, many one-parameter families of triply periodic minimal surfaces of genus three have been considered. In 1990s, the moduli theory of triply periodic minimal surfaces established by C. Arezzo and G. P. Pirola [1], [14], and they studied a relationship between the nullity of a minimal surface and the differential of its real period map from the viewpoint of complex geometry. The present paper develops their theory in terms of a real differential geometric aspect, and, by applying the classical transversal property to the real period map, we obtain the numerical evidence for the existence of real nine-dimensional manifolds of triply periodic minimal surfaces which include such one-parameter families. For each case that the transversal property fails, we give values of parameters from which new one-parameter families of triply periodic minimal surfaces issue.

Simulation of laser plasma wakefield acceleration with external injection based on Bayesian optimization

Abstract In laser wakefield acceleration (LWFA), injecting an external electron beam at certain energy is a promising approach to achieving high-quality electron beam with low energy spread and low emittance. In this paper, the process of laser wakefield acceleration with an external injection at 10 pC has been studied in simulations. A Bayesian optimization method is used to optimize the key laser and plasma parameters, so that the electron beam is accelerated to the expected energy with a small emittance and energy spread growth. The effect of rising edge of the plasma on the transverse properties of the electron beam is simulated and optimized in order to ensure that the external electron beam is injected into the plasma without significant emittance growth. Finally, a high-quality electron beam with an energy of 1.5 GeV, the normalized transverse emittance of 0.5 mm·mrad and the relative energy spread of 0.5% at 10 pC is obtained.

Time-varying deterioration of bamboo mechanical properties

Bamboo is a type of fast-growing and renewable natural resource that is an ideal building material. In this study, the longitudinal tensile, longitudinal compressive, flexural, longitudinal shear, transverse tensile, and transverse compressive stress-strain and strength properties of bamboo with a period of 240 days were conducted to study the time-varying deterioration performance of bamboo. The results showed that the mechanical properties of bamboo decreased gradually with the passage of time. The transverse compressive strength deteriorated the most, and the longitudinal tensile strength deteriorated the least. After 240 days of tests, bamboo CCS decreased by 52.5% and UTS decreased by 25.4%. Formulas to predict deterioration of mechanical properties were put forward and validated. It was found that the nodes of bamboo influenced its mechanical properties. The deterioration degree of the test specimens with nodes was slightly higher than that of the test specimens without nodes. These findings provide evidence about the deterioration mechanism of bamboo and are significant for promoting the development of bamboo architecture.

Transverse energy absorption performance of sandwich tubes with various origami foldcores

Nowadays, composite sandwich tubes are extensively utilized in the civil and aerospace industries due to their superior strength-to-weight mechanical properties. Origami-based core offers a large enhancement of the mechanical properties, yet little study research focuses on the effect of various foldcore configurations on the transverse mechanical properties of sandwich tubes, necessitating the design method for applications. This study introduces an innovative approach by incorporating origami into the composite sandwich core to enhance the transverse energy absorption capacity. The quasi-static transverse mechanical properties of carbon fibre-reinforced polymer (CFRP) sandwich tubes with foldcores are studied under three-point bending-like local compression and transverse structural compression. A systematic geometric design framework and numerical modelling technique are provided. By integrating finite element analysis and experiments, the research investigates the effects of various origami foldcore configurations and geometric parameters on transverse energy absorption capacity. The experiment setup is provided by sandwich tubular specimens with a full-diamond configuration as the foldcore. The cylindrical tubes (foldcore) of the sandwich structures were manufactured using four plies [0°]4 of T700 (T300) woven CFRP with the hot press moulding (vacuum bag using female and male moulds) technique respectively. Then, the parametric study and damage mode analysis of eight different foldcore patterns (axial Miura, circumferential Miura, diamond, Kresling, and their curved-creased counterparts) were studied. The results showed the superior energy absorption performance of the sandwich tube with Miura-pattern foldcore over the origami-pattern counterparts, nested tube, and traditional honeycomb sandwich tube with CFRP or aluminium-made cores. Therefore, the structural parameters optimisation of the Miura pattern tube was carried out by the Response Surface method (RSM) and a design strategy for increasing the energy absorption capacity was found. The findings offer guidance for designing high-specific energy absorption tubular structures for future advanced engineering applications.

Ab-initio prediction of gigantic anomalous Nernst effect in ferromagnetic monolayer transition metal trihalides

The anomalous Hall conductivity of all transition metal trihalides was explored using first-principles calculations. Employing the Fukui-Hatsugai-Suzuki method, we found that ferromagnetic monolayersXBr3(X= Pd, Pt) possessed the quantized anomalous Hall conductivity (QAHC) with and without carrier doping. Due to unique QAHC, their transverse thermoelectric properties ofXBr3(X= Pd, Pt) were investigated. Employing the semi-classical Boltzmann transport theory, the transverse thermoelectric coefficient of each monolayer was analyzed. Anomalous Nernst coefficients (ANCs) of theXBr3monolayers were prominent both at and near the Fermi level. Under an assumed relaxation time of 10 fs, the maximum ANCs for the PdBr3(PtBr3) monolayer reached -54.1 (-23.3)µV K-1atT=300 K upon doping with 1.21 × 1014(5.64 × 1013) holes cm-2. The large ANCs of theXBr3monolayers were attributed to the opening of a narrow bandgap generated by spin-orbit coupling both at and near the Fermi level, which led to a large Seebeck-induced charge current and large anomalous Nernst conductivity. These results suggest that ferromagneticXBr3monolayers have significant potential for application in thermoelectric devices.

The effect of enzymatic GAG degradation on transverse shear properties of porcine cornea

The structural integrity of cornea depends on properties of its extracellular matrix, mainly a mixture of collagen fibers and soluble proteoglycans (PGs). PGs are macromolecules of negatively charged sulphated glycosaminoglycans (GAGs) covalently attached to a protein core. GAGs appear as bridges between adjacent collagen fibers and could facilitate force transfer between them. Furthermore, GAGs are responsible for corneal hydration by attracting and maintaining water molecules into the extracellular matrix. Based on these observations, GAGs are expected to be essential for biomechanical properties of cornea. The primary objective of the present study was to determine the effects of GAGs on shear properties of cornea. For this purpose, GAGs were enzymatically removed from porcine corneal disks by keratanase II enzyme. After confirming the successful removal of GAGs by histochemical methods, torsional rheometry was performed to characterize the shear stiffness of GAG-depleted samples as a function of axial strain. It was found that the shear modulus of all samples was a function of applied shear strain and compressive strain. Beyond the range of linear viscoelastic response, the average complex shear modulus decreased with increasing the shear strain. Increasing the axial strain from 0% to 40% significantly increased the average complex shear modulus of corneal disks in all groups. Finally, the enzyme treatment with keratanase II enzyme significantly decreased the shear stiffness. The experimental measurements were discussed in terms of microstructural and compositional properties of corneal extracellular matrix and it was concluded that GAGs play a significant role in defining shear properties of cornea.

Dynamic Progressive Failure Analysis of 3D Five-directional Braided Composites under Transverse Compression Based on Macro-scale Heterogeneous Model

At present, there are few systematic researches on macro-scale heterogeneous modeling and numerical simulation of dynamic mechanical properties of 3-D braided composites. In this paper, the parametric virtual simulation model of 3D five-directional braided composites is realized in the way of “point-line-solid” based on the integrated design idea of process-structure-performance. And the impact compression numerical simulation of the material is carried out by using multi-scale analysis method. The effects of strain rate and braiding angle on transverse impact compression properties and fracture characteristics of composites is studies and verified by comparing the test results with the numerical simulation results systematically. The dynamic failure mechanism of the matrix and fiber bundles during the impact compression process is revealed. The results show that the macro-scale heterogeneous simulation model of 3D five-directional braided composites established is effective, and the numerical simulation results agree well with the test results. The matrix fracture and shear failure of fiber bundles are presented simultaneously under transverse impact compression. The failure of fiber bundles and matrix mainly concentrates on two main fracture shear planes. And the included angle between the fracture shear planes and the vertical direction is consistent with the corresponding internal braiding angle of specimens.

Self-powered highly stretchable ferroelectret nanogenerator towards intelligent sports

Ferroelectret nanogenerators (FENGs), recognized for their porous structures that facilitate charge retention, thereby creating giant electric dipoles and exhibiting remarkable piezoelectric properties, are utilized in the development of various flexible transducers. However, despite their flexibility, most developed ferroelectret nanogenerators lack adequate stretchability and satisfactory transverse piezoelectric properties, significantly inhibiting their widespread deployment in wearable or skin-mounted electronics. Here, we introduce a highly stretchable ferroelectret nanogenerator (HS-FENG) built from laser-induced graphene (LIG), Ecoflex and anhydrous ethanol, demonstrating exceptional flexibility and stretchability, along with longitudinal and transverse piezoelectric effects. The stretchability of HS-FENG can reach a record of 468 %, while the quasi-static piezoelectric coefficients d33 and d31 are approximately 120 pC/N and 70 pC/N, respectively. To our knowledge, this is the first demonstration of the developed FENG with remarkably high stretchability. Furthermore, leveraging the performance of the created HS-FENG, we construct a skin-mounted intelligent kinesiology tape capable of effectively monitoring motion signals from human muscles and joints, thereby offering a deeper understanding of movement for users across different levels of physical activity, from professional athletes to individuals undergoing rehabilitation. The development of intelligent kinesiology tape exemplifies the potential of HS-FENG technology in enhancing professional athletic training and personalized healthcare. It contributes to the advancement of inconspicuous skin-mounted biomechanical feedback systems and human-machine interfaces, marking progress in the field.

Increasing the Interlayer Fracture Toughness of Polymer Fabric Composites Using Local 3D-Reinforcement (Felting)

Introduction. One of the reasons for undesirable delamination of polymer composites with fabric reinforcement is low transverse shear properties. It is known that the reinforcement of polymer fabric composites in the Z direction reduces the sensitivity to delamination and increases the viscosity of interlayer fracture. Various methods of three-dimensional reinforcement of polymer fabric composites are proposed in the literature. However, they complicate the manufacturing process of the structure. The problem is solved by the method of three-dimensional reinforcement proposed in this article — felting. This is a local reinforcement of the composite in the Z direction with minimal production changes. The degree of Z-reinforcement is determined by the felting density, i.e., the number of needle punches per 1 cm2 of the fabric package. The work is aimed at evaluating the effect of felting on the interlayer crack resistance of a composite material.Materials and Methods. The interlayer fracture toughness GIIc was determined on a cross-woven fiberglass with felting of 10 cm-2. The material was impregnated with Etal-370 resin and Etal-45 hardener. Experiments according to ASTM D7905M–14 and GOST 33685–2015 standards were carried out on an Instron 5900R test machine. The stress state at the crack tip was analyzed with regard to the nonlocal strength theory in the ANSYS Workbench program (option “static strength analysis”). The finite element method (FEM) was used.Results. The “load — displacement” curves were considered for the samples. Values GIIc were calculated. The results of ENF tests for felting density of 0 cm–2 and 10 cm–2 were summarized. Control samples and felting samples were compared. In the latter case, GIIс turned out to be ~33% higher. The stress state at the crack tip was calculated under DCB and ENF loading. The dependences of maximum normal and shear stresses, as well as displacements, were visualized in the form of graphs and color charts. To get the calculated “load — displacement” dependences using FEM, the reverse method of obtaining transverse shear constants was used. DCB loading showed that felting provided increasing the rupture strength in the Z direction to ~18%, by 39 to 46 MPa, and in the planes XZ— to ~16%, by 77 to 89 MPa.Discussion and Conclusion. Felting as a method of local three-dimensional reinforcement enhances the interlayer crack resistance of polymer fabric composites. It provides reducing the area of stratifications after local impacts during the operation of structures. Flexible felting technology makes it possible to create zones with an arbitrary impact density, increasing fracture toughness only in the required places of structures. The FEM analysis of the stress state at the crack tip within the framework of the nonlocal strength theory has shown that in strength calculations, the stratification crack can be considered as a stress concentrator.

Higher-order sensitivity analyses to understand the role of FE input parameters on the simulation of composites in progressive fracture tests

With the rise of data-driven engineering methods, such as machine learning, a comprehensive understanding of the underlying data fed into these algorithms is required for effectively applying these methods. This study presents two highly efficient Finite Element (FE) models that operate at different length scales, based on Continuum Damage Mechanics (CDM). The combination with Random Sampling-High Dimensional Model Representation (RS-HDMR) enables the determination of influential FE input parameters and their correlations to simulate Fibre Reinforced Polymer (FRP) composites subjected to a variety of progressive fracture tests in tension and compression. The results indicate that laminate-based models utilise the FE input parameters efficiently where all parameters are found to be influential. On the other hand, only fibre-related properties are relevant in ply-based FE models, with all input parameters related to transverse properties deemed to be non-influential. The findings of this study aid in identifying suitable fracture tests for a meaningful calibration and validation of CDM-based FE models. Moreover, the study lays the foundation for understanding the role of input parameters within data-driven methods, and for developing efficient reduced-order models or surrogates for uncertainty quantification on the damage tolerance of FRP composites.

Micro-buckling resistant unidirectional glass fiber composites with excellent transverse and longitudinal flexural properties from cross-linking by nano-/micro-aramid fibers

This study aims at obtaining an effective structural design strategy for stronger and more reliable Unidirectional glass fiber (UD-GF) composites by in-situ formed cross-linking from randomly distributed nano-/micro- Aramid pulp (AP) fibers. The flexural strength and stiffness have shown substantial improvements in both the transverse and longitudinal directions due to the AP cross-linking and the “brick-slurry” structure. With AP of 8 g/m2, up to 60–70 % improvement in flexural strengths (both transverse and longitudinal directions) and up to 20–37 % improvement in “effective modulus” have been observed. The noticeable longitudinal improvements have been attributed to the resin reinforcement and interlayer cross-linking provided by ultra-thin AP interlayers, and the resultant improvement in micro-buckling resistance under compression. Since sparsely distributed nano-/micro-AP can be readily incorporated in pultrusion and pre-preg manufacturing processes, this study is not only important for micro-mechanism study, but also provides a plausible improvement in manufacturing.

Interface wear law and modeling between yarns in woven CMC under cyclic loading

Friction and wear between warp and weft yarns affect the mechanical behavior of woven CMC. This paper conducts tensile and fatigue testing on unidirectional and woven CMCs without interphase to examine the influence mechanism of friction and wear between yarns on woven CMCs. Linear reciprocating friction experiments between minicomposites are carried out to demonstrate the degradation relationship of the friction coefficient with the cycle number. Interface elements are established between yarns in woven CMC to obtain the transverse equivalent constitutive relationship of the weft yarns at different friction coefficients. In other words, the variation relationship of the transverse mechanical properties of the weft yarns with the cycle number is determined. This method is utilized to the fatigue life prediction of woven CMC under cyclic loading. It achieves precise predictions of the fatigue life of woven CMC, with the prediction accuracy within a scatter range of four times.

Simultaneous enhancement of axial/transverse compressive strength of aramid fibers by the construction of branched multi-hydrogen bonding sites

The terrible compressive strength is a prominent issue that restricts the broad application of organic fibers in multi-dimensional stress scenarios. Traditional strategies focus on enhancing the axial compressive performance of fibers, simultaneously improving the axial and transverse compressive properties of fibers still poses significant challenges. Inspired by the octopus's tentacles that can conduct stress in multiple directions, a novel strategy by constructing branched multi-hydrogen bonding sites structure in aramid fiber was conducted to solve the problem. The branched multi-hydrogen bonding sites constructed on nano-silica (SiO2–B) offer excellent dispersibility within the poly(p-phenylene-benzimidazole-terephthalamide) (PBIA) matrix. Composite fibers (PBIA-SiO2-B) co-mixed with SiO2–B and PBIA were prepared using a solution spinning technique. The results of Fourier-transform infrared spectroscopy (FTIR) and dynamic mechanical analysis (DMA) reveal that the introduction of SiO2–B significantly enhances the intermolecular interactions within the composite fibers, and this enhancement mechanism has been elaborately elucidated through molecular simulations. Furthermore, finite element simulations confirmed that the incorporation of branched structure exhibits enhanced stress-bearing capabilities under multi-directional stress and offers outstanding support when subjected to transverse compressive stress compared to linear molecular chains. Hence, compressive property testing revealed that the PBIA-SiO2-B composite fibers achieved axial compressive strengths and transverse compressive strengths of 714.3 MPa and 305.8 MPa, respectively, representing increases of 68.8 % and 26.8 % over pure PBIA fibers. Moreover, with the enhancement of transverse compressive strength, the Young's modulus and interfacial shear strength of PBIA-SiO2-B fibers were also increased by 7.1 % and 20.9 %, respectively.

Study of the effect of void defects on the mechanical properties of fiber reinforced composites

This study is to investigate the mechanical properties of fiber-reinforced polymer (FRP) composites considering void defects by adopting a representative volume element model. The results reveal that initial damage always sprouts at the interface, the void defects affect the location of the initial damage and are the dominant factor in determining the stress required for damage sprouting. In addition, the void defects as well as the neighboring debonding interfaces together determine the direction of the main damage evolution zone. The transverse tensile properties are most affected by the void defects, while the longitudinal tensile properties are least affected. In particular, the strength is more sensitive to void defects than that of elastic constants. In addition, the mechanical properties of high Fiber Volume Fraction (FVF) FRP composites are significantly stronger affected by void defects than those of low FVF FRP composites.

Comparison of Rolling and Transverse Direction Properties of Al/Ti Laminated Metal Composites Prepared by Cold Roll Bonding and Subsequent Annealing

Comparison of Rolling and Transverse Direction Properties of Al/Ti Laminated Metal Composites Prepared by Cold Roll Bonding and Subsequent Annealing

Exploring anisotropic pressure and spatial correlations in strongly confined hard-disk fluids: Exact results.

This study examines the transverse and longitudinal properties of hard disks confined in narrow channels. Employing an exact mapping of the system onto a one-dimensional polydisperse, nonadditive mixture of hard rods with equal chemical potentials, we compute various thermodynamic properties, including the transverse and longitudinal equationsof state, along with their behaviors at both low and high densities. Structural properties are analyzed using the two-body correlation function and the radial distribution function, tailored for the highly anisotropic geometry of this system. The results are corroborated by computer simulations.

Effect of hollow glass microspheres on transverse properties of carbon fiber reinforced epoxy composites

AbstractHollow glass microsphere (HGM)—based composites are gaining popularity in materials research due to their ability in altering material characteristics drastically. The current study investigates HGMs filled carbon fiber reinforced epoxy (CE) composites on transverse properties, aiming for aerospace and defense applications mainly in composite pressure vessels. Unidirectional laminates of Carbon/Epoxy with varying HGM percentages (0.2, 0.4, 0.6, 0.8, 1.0 wt. %) were wounded onto a flat‐plate mandrel using a 4‐axis filament winder, along with a baseline sample without HGM for comparison. The glass transition temperature (Tg) and thermal stability were analyzed by carrying out dynamic mechanical analysis and thermogravimetric analysis. The fracture mechanism of the samples loaded under tension was investigated using FESEM. Experimental results indicate reduction in density with increase in HGM content, up to 0.4% HGM there is increase in transverse tensile strength of 25% compared to baseline and further increase in HGM content, decrease trend is observed. 30% decrease in transverse compressive strength is observed compared from baseline to 1.0 wt. % of HGM. No significant change was noticed in the thermal stability and Tg on introduction of HGM. Microscopy images of fractured samples revealed effective physical interaction and dispersion of the HGM within the matrix.Highlights Transverse mechanical properties are tested to know the influence of HGM filler on filament wound composites. Density of the composite decreases with increase in HGM content. Thermal stability and Tg shows less change on introduction of HGM in composites.

Magnetic field sensing elements based on Ni80Fe20 2D magnetoplasmonic crystals

Here we demonstrate the fabrication of magnetic field sensing elements based on 2D magnetoplasmonic crystals prepared using e-beam lithography and magnetron sputtering methods. The magnetoplasmonic crystals consist of square lattice diffraction gratings with varying filling factors layered with Ag, Ni80Fe20, and Si3N4 layers. Based on the magnetic, optical, and magneto-optical studies, the magnetoplasmonic crystal that allows for both high transverse Kerr effect and isotropic in-plane magnetic properties along the diffraction grating vectors was determined. The sensitivity and measuring range of this sample provide a perspective for measuring several components of an external magnetic field.

Controlled Interlayer Binding and Healing Improve the Transverse Properties of Upcycled Disposable Waste Wood.

Recovery and reuse of bulk waste wood are particularly challenging because of usage defects and contaminations. Here, we present a robust and efficient strategy for regenerating used wood veneers into high-performance structural materials through micro/nano interface manipulation. Our approach involves using cellulose-based interlayers to bind together two waste wood plates without an external adhesive by partially dissolving and regenerating the interlayer using a solution of ionic liquids and dimethyl sulfoxide. The mechanical properties of the regenerated wood exceed that of natural wood, displaying over a 16 and 20 times increase in transverse tensile strength and modulus, respectively, and 4-6 times improvement in longitudinal tensile strength and modulus. Nanoscale mechanical analyses show that the improvement is possible as a result of several factors, including the robust network structure of the interlayer, the good adhesion at the wood-interlayer interface, the compacted wood structure, and the low stiffness and deformation gradients between the interlayer and the wood structure. The interlayers can be created from waste papers and wood particles by taking advantage of the nanofibrillar structure of cellulose.

Piezoelectric Enhancement in P(VDF-TrFE) Copolymer Films via Controlled and Template-Induced Epitaxy.

The surge in wearable electronics and Internet of Things technologies necessitates the development of both flexible sensors and a sustainable, efficient, and compact power source. The latter further challenges conventional batteries due to environmental pollution and compatibility issues. Addressing this gap, piezoelectric energy harvesters emerge as one kind of promising alternative to convert mechanical energy from ambient sources to electrical energy to charge those low-energy-consumption electronic devices. Despite slightly lower piezoelectric performance compared with those inorganic materials, piezoelectric polymers, notably poly(vinylidene fluoride-co-trifluoroethylene) P(VDF-TrFE), offer compelling properties for both flexible mechanical energy harvesting and self-powered strain/stress sensing, though their piezoelectric performance is expected to be further enhanced via varieties of modulation strategies of microstructures. Herein, we reported the controlled epitaxy process of micrometer-thick copolymer films with the cooperation of friction-transferred poly(tetrafluoroethylene) templates and precise modulation of the annealing conditions. Epitaxial P(VDF-TrFE) films present averaged d33 piezoelectric coefficient of -58.2 pC/N between 50 Hz and 1 kHz with good electromechanical and thermal stability. Owing to the nature of anisotropic crystallization, the epitaxial films exhibit an anisotropic transverse piezoelectric property. Epitaxial films were further utilized for mechanical energy harvesting and monitoring of human pulsation and respiration. This study provided a feasible route for the development of high-performance flexible piezoelectric devices to meet the requirement of flexible electronics.