Biaxial Layer Research Articles

Functionalized Interlayers in Self‐Powered Organic Photodiodes for Enhanced Near‐Infrared Sensing

AbstractThere is a growing interest in fabricated organic material‐based photodiodes (OPDs) since they are lightweight, flexible, and cost‐effective to manufacture. Notably, they exhibit near‐infrared photo‐sensing capabilities that are self‐powered, a feature attributed to the tunable optical properties of organic semiconductor (OSC) materials. Nonetheless, the application of OPDs in the semiconductor industry encounters challenges compared to their inorganic counterparts, such as low sensitivity and limited durability. In this study, a self‐powered OPD using a poly[4,8‐bis(5‐(2‐ethylhexyl)thiophen‐2‐yl)benzo [1,2‐b:4,5‐b′]dithiophene‐2,6‐diyl‐alt‐(4‐(2‐ethylhexyl)‐3‐fluorothieno[3,4‐b]thiophene‐)‐2‐carboxylate‐2‐6‐diyl)]:biaxial active layer of phenyl‐C70‐butyric acid methyl ester (PTB7‐Th:PC70BM) and an organic hole transport layer (HTL) composed of poly(3,4‐ethylenedioxythiophene) and poly(styrene sulfonate) (PPY:PSS) is developed. These results highlight the effectiveness of PPY:PSS as an HTL, demonstrating distinct improvements in efficiency, photosensitivity, photo‐detectivity, and operational stability of the OPD when the weight ratio between the PPY and PSS is 1:2.

Effects of the internal pressure and stacking sequence on the transverse impact behavior of hybrid uniaxial-biaxial braided composite tubes

In this paper, the response of hybrid uniaxial and biaxial braided composite tubes subjected to transverse low-velocity impact under internal pressure load is studied experimentally. Two groups of specimens without internal pressure (0 MPa) and with internal pressure (2 MPa) are set up for low-velocity impact test, and the energy is set to 10 J, 20 J and 30 J. The Micro-CT damage reconstruction is performed to evaluate the impact damage mechanisms of hybrid tubes. The results show that the impact resistance of structural hybrid specimens is better than that of pure uniaxial and biaxial braided specimens. The position of biaxial braided layer is the main factor to distinguish the performance of hybrid composite tubes. Based on the characteristics of yarn interlacing, when the biaxial braided layer is arranged in the outermost layer, the intralaminar crack propagation is inhibited to protect the surface of the specimen. The damage area is dispersed to reduce the stress concentration, while it is placed in the innermost layer. The existence of internal pressure mainly affects the distribution and degree of yarn damage, which can significantly improve the impact resistance of tubes.

SERS sensing of Metanil yellow in turmeric solution using self-organized nanoparticle arrays grown on Ion beam patterned soda-lime glass

Metanil yellow is a potential carcinogen that is commonly used as a food adulterant in turmeric powder. In this study, we detected Metanil Yellow from turmeric powder solution using a Surface Enhanced Raman Spectroscopy (SERS) substrate based on nano patterned soda-lime glass. Low amplitude ripples with an average wavelength around 65 nm was produced on commercially available soda-lime glass using low energy argon ion beam irradiation. Large area SERS templates were produced by growing self-organized ordered Ag nanoparticles on the rippled soda-lime glass. The optical analysis of the produced substrates shows the anisotropic plasmonic response and better Localized Surface Plasmon Resonance (LSPR) activity than Ag nanoparticles grown on rippled Si substrate. A biaxial layer consisting of Lorentz and Drude oscillators describes the real and imaginary parts of the dielectric function. The SERS analysis using Crystal Violet (CV) molecules demonstrates a five-fold improvement in the efficiency of silver grown on glass ripples than silver grown on Si ripples. We have tested the substrate for detecting Metanil yellow up to 10-6 M concentration in the water. Further, using the substrate, up to 10-4 M concentration of Metanil Yellow is detected from the turmeric solution.

Structural Design and Analysis of Sliding Composite Mono Leaf Spring

<div>The lightweight structure of a semitrailer composite leaf spring is designed and manufactured using glass fiber composite to replace the conventional steel leaf spring. The sliding composite mono leaf spring was designed based on the conventional parabolic spring design theory. The composites product design (CPD) module of CATIA software is used to create the lamination of the composite leaf spring. Using finite element analysis of the position and proportion of ±45° biaxial layer by OptiStruct software, it is found that a certain proportion (nearly 5%) of a ±45° biaxial layer can effectively reduce the shear stress under the condition of keeping the total number of layers fixed. Then, the natural frequency, stiffness, and strength of the composite leaf spring are simulated by the finite element method. Finally, the stiffness, fatigue, and matching of the designed spring are tested by experiments. The design weight of the composite leaf spring is 18.5 kg, which is 55.4% lighter than the conventional steel leaf spring. The composite mono leaf spring has good fatigue performance; the vertical fatigue cycles are more than 300,000 times, 1.6 times of the traditional steel leaf spring. The results of the system bench test show that the movement state of the composite mono leaf spring is consistent with the steel leaf spring. It can be preliminarily speculated that the composite leaf spring structure can meet the requirement of vehicles. A proposed method combining theoretical analysis, calculation, and finite element simulation can be used to design and test composite products quickly. This method has a high significance for the structural optimization of other laminated composite products.</div>

Investigation of the effect of using geogrid, short glass, and steel fiber on the flexural failure of concrete beams

This research studies the flexural behavior of concrete beams reinforced with biaxial geogrids, distributed short glass and steel fibers. No longitudinal steel reinforcement bars were used. Therefore, an amount of short glass and steel fibers was used to improve the concrete beam behavior against flexural failure. Eleven specimens of single reinforced (flexural reinforcement) concrete beams and double reinforced (compression and flexural reinforced) concrete beams using two biaxial geogrids sheet layers, with randomly distributed short glass and steel fibers were cast. The samples were tested using two points of load along the beam specimen span with an increment of loading by 5 KN to evaluate several parameters. The studied parameters are using geogrids as a main flexural reinforcement, using geogrid sheet layers as a flexural and compression reinforcement, using short glass and steel fibers as an additional reinforcement of concrete with various ratios 0.25 %, and 0.75 %. The test results indicated that the use of geogrid layers as the main flexural reinforcement improved the behavior of the concrete beam specimens at failure. As well as; more enhancement of beam specimens at failure was observed when using short glass and steel fibers with geogrid reinforcement in concrete beams. The tested beam specimens which were reinforced by geogrids in the flexural and compression zone using 0.75 % of steel fibers gave better results due to modes of failure, toughness, failure load capacity, crack width, and post cracking stiffness.

Drying shrinkage and thermal expansion of metakaolin-based geopolymer concrete pavement reinforced with biaxial geogrid

The most often used material in concrete pavement slabs is ordinary Portland cement concrete (OPC). Many of OPC pavement slabs crack due to drying shrinkage and thermal expansion of OPC before applying traffic loads. Geopolymer concrete is an environmentally friendly type of concrete that achieves early strength without the need of moisture curing and can be strengthened further by heating. Metakaolin – based geopolymer concrete (GPC) present a suitable behavior against volumetric changes in previous researches. Biaxial geogrid layers can be an effective and durable alternative for steel reinforcement to reduce cracks propagation and volumetric changes in concrete. In this research, biaxial geogrid reinforced GPC was investigated to evaluate its drying shrinkage and thermal expansion properties which affect cracks propagation due to thermal volumetric changes in concrete pavement slabs. Geogrid reinforcing in GPC and OPC displayed a suitable performance against drying shrinkage and thermal expansion. Biaxial geogrid reinforcement in GPC resulted in about 48% reduction in drying shrinkage strains and 45% reduction in thermal expansion strains.

The hybridization effect and damage sequence investigation of biaxial/unidirectional braided composite tubes by micro-CT method

Thanks to the 2D braiding manufacturing method, the hybrid braided composite composed of the biaxial and unidirectional layers is available in a mass-production manner. For enhancing the crashworthiness of braided composite tubes, the damage characteristics and energy absorption capacity of braided composite with biaxial/unidirectional hybridization structures under axial compression were studied in this work. The axial compression tests were conducted on pure biaxial and unidirectional braided tubes (BBB and UUU), and hybrid tubes with different surface and inner layers (BUB and UBU). Micro-CT was utilized to analyze the crack characteristic and propagation inside the tubes. It was found that the easily progressed intra-laminar cracks in unidirectional layers promoted splitting damage feature, leading to enhanced energy absorption capacities in hybrid tubes than pure biaxial braided tube, in which local buckling damage feature was observed attributed to interlaced yarns induced constrained intra-laminar crack propagation and tendency to delamination. In particular, the UBU tube dissipated 20.4% more crushing energy and exhibited 13.0% higher energy absorption per unit area than the BBB tube.

Transverse impact response of hybrid biaxial/uniaxial braided composite tubes

Tubular composites in automobile engineering are susceptible to transverse loading events. This paper deals with transverse low-velocity impacts on interply hybrid tubes made of biaxial/uniaxial braided fabric layers. For comparison, drop weight tests were performed on hybrid tubes with biaxial braided surface layers and uniaxial braided inner layer (BUB), with contrary stacking sequence (UBU), pure biaxial and uniaxial braided tubes (BBB and UUU). Numerical models were established to predict the impact behaviors and evaluate the hybrid effects. X-ray micro-computed tomography (Micro-CT) was also employed to identity the cracking location and characterize the damage mechanism. The results showed that the impact response of braided tube was related to its structural deformation resistance, which was determined by properties of reinforced layers varying with different stacking sequence. The hybrid effect became more obvious at higher impact energy. At impact energy of 15.4 J, hybrid tube (BUB) yielded the highest impact resistance with small structural deformation. The biaxial braided layer protected the specimen surface by constraining intralaminar crack propagation through the interlacing patterns. Meanwhile, it promoted crack tip propagating to the subsequent uniaxial braided layer and transferred the impact load. Thus, the material involvement of the inner layer was improved, which was responsible for providing a higher in-plane tensile property due to its low yarn crimp.

Mechanical behaviour and microscopic analysis of epoxy and E-glass reinforced banyan fibre composites with the application of artificial neural network and deep neural network for the automatic prediction of orientation

This paper deals with the testing of tensile and flexural behaviour of epoxy-reinforced natural fibre composites, for which Banyan fibres have been selected as the natural fibre. Variations are made in the orientation of the fibres to determine which orientation made the composite the strongest. The fibre strands are arranged in different orientations, such as the uniaxial, biaxial and criss-cross arrangements, to differentiate between the orientations and observe which arrangement exhibited the best mechanical behaviour. The fibres are initially washed with 0.5% weight/volume (w/v) NaOH solution, following which specimens of the composites are made using wooden moulds designed according to ASTM standards. Biaxial layers of E-glass are incorporated into the matrix in an attempt to enhance the mechanical properties of the specimen. The variances observed in the Young’s modulus are analysed to understand the factors that majorly impacted it. For a better understanding of the results, the chemical functional groups and the microstructure of the samples are analysed with the aid of Fourier-Transform Infrared Spectroscopy (FTIR), Field Emission Scanning Electron Microscopy (FESEM) and X-Ray powder Diffraction (XRD). Additionally, predictive models are simulated using Artificial and Deep Neural Networks to recognise patterns in the data, by varying specific parameters. The results obtained indicated that Banyan fibre composites can replace conventionally-used materials and serve real-world purposes better.

Terahertz-frequency dielectric anisotropy in three-dimensional polymethacrylates fabricated by stereolithography.

The anisotropic optical dielectric functions of slanted columnar layers fabricated using polymethacrylate based stereolithography are reported for the terahertz-frequency domain using generalized spectroscopic ellipsometry. The slanted columnar layers are composed of spatially coherent columnar structures with a diameter of 100 µm and a length of 700 µm that are tilted by 45° with respect to the surface normal of the substrates. A simple biaxial (orthorhombic) layer homogenization approach is used to analyze the terahertz ellipsometric data obtained at three different sample azimuthal orientations. The permittivity along the major polarizability directions varies by almost 25%. Our results demonstrate that stereolithography allows tailoring of the polarizability and anisotropy of the host material, and provides a flexible alternative metamaterials fabrication method for the terahertz spectral range.

In-plane optical anisotropy and SERS detection efficiency of self-organized gold nanoparticles on silicon nanoripples: Roles of growth angle and postgrowth annealing

In this work, we report on substrate morphology-mediated plasmonic anisotropy and surface-enhanced Raman scattering-based molecular detection efficacy of oblique angle grown self-organized gold nanoparticles (Au-NPs) on ultralow energy ion-beam fabricated nanoscale rippled-Si (R-Si) substrates. To study the effect on plasmonic field coupling, the shape of Au-NPs is tuned from elongated to spherical ones by varying the growth angle leading to a change in the interparticle gap. Following this, postgrowth annealing of Au-NP arrays is carried out to change the shape and size of Au-NPs via Ostwald ripening process. The optical anisotropy is measured using generalized ellipsometry, while dielectric functions of Au-NP arrays are calculated using a biaxial layer model by fitting the Jones matrix elements. A stronger plasmonic field coupling becomes evident from the imaginary part of dielectric functions along x- and y-axes which is further supported by finite-difference time-domain (FDTD) simulations. Enormous near-field enhancement between Au-NPs leads to surface-enhanced Raman scattering (SERS)-based detection of an ultralow concentration (10 μM) of crystal violet dye. Further, FDTD simulation reveals that hotspot formation takes place between Au-NPs due to lesser interparticle gaps along the Au-NP arrays compared to the ones between two adjacent arrays. Thus, Au-NP arrays exhibit in-plane anisotropic optical response. The improved SERS-based detection efficacy of complex molecules is attributed to their enhanced Raman scattering cross-section in the vicinity of these hotspots. This study demonstrates that self-organized Au-NP arrays on nanoscale rippled-Si substrates can work as an efficient and longevous SERS sensor due to the prolonged stability of Au in environmental conditions. This study will pave the way to fabricate plasmonic devices and SERS-based sensing of complex molecules having low Raman scattering cross-sections.

Temperature Dependency of the Deformation Behavior of Hybrid CFRP/Elastomer/Metal Laminates under 3-Point Bending Loads

Fibre-metal-elastomer laminates offer the possibility of using material combinations which often have to deal with premature delamination, for example due to different coefficients of thermal expansion or galvanic corrosion due to different electronegativities. The present study deals with laminates made of layers of CFRP and aluminum, each of which is bonded together by an elastomer layer. The shear-soft elastomer also allows the much stiffer aluminum and CFRP layers to be sheared off against each other under bending stress. This leads to complex deformation behavior. The shear of the elastomer also plays a crucial role in the damping behavior of the laminate. Due to large shear deformations in the elastomer layer, the combination of rigid layers and soft elastomer layers shows very good damping behavior according to the principle of constrained layer damping. Since bending vibrations that occur during normal use usually have only small amplitudes, the deformation behavior is of particular interest in the elastic range. Since this deformation behavior is strongly dependent on the shear modulus of the elastomer used and this in turn is strongly influenced by temperature, the deformation behavior is characterized at different temperatures. Within the scope of this investigation, quasi-static 3-point bending tests are carried out on different laminate lay-ups in the temperature range from -40 °C to +80 °C. The laminates are consolidated by compression molding and contain two different EPDM elastomers in varying layer thicknesses, unidirectional CFRP prepreg in biaxial layer lay-up and aluminum 2024 sheets. The deformation behavior is analyzed by digital image correlation. This is used to measure both the bending line of the overall composite and strains over the layer thickness. In particular, the shear in the elastomer layers is evaluated and set in relation to the bending lines. Finally, the ability of the laminate lay-up to damp bending vibrations is evaluated.

Flow and heat transfer over a permeable biaxial stretching/shrinking sheet in a nanofluid

This paper studies the biaxial boundary layer flow of a nanofluid past a stretching/shrinking sheet. A suitable similarity transformation simplifies the system of partial differential equations into a system of ordinary differential equations. The obtained system of the governing ordinary differential equations is then solved numerically by using the bvp4c function from MATLAB. The generated numerical results are presented graphically and discussed in the relevance of the governing parameters. Dual solutions are found as the sheet is shrunk in the horizontal direction. Stability analysis shows that the first solution is physically realizable whereas the second solution is not practicable.

Schottky barrier tuning via dopant segregation in NiGeSn-GeSn contacts

We present a comprehensive study on the formation and tuning of the Schottky barrier of NiGeSn metallic alloys on Ge1-xSnx semiconductors. First, the Ni metallization of GeSn is investigated for a wide range of Sn contents (x = 0–0.125). Structural analysis reveals the existence of different poly-crystalline NiGeSn and Ni3(GeSn)5 phases depending on the Sn content. Electrical measurements confirm a low NiGeSn sheet resistance of 12 Ω/□ almost independent of the Sn content. We extracted from Schottky barrier height measurements in NiGeSn/GeSn/NiGeSn metal-semiconductor-metal diodes Schottky barriers for the holes below 0.15 eV. They decrease with the Sn content, thereby confirming NiGeSn as an ideal metal alloy for p-type contacts. Dopant segregation for both p- and n-type dopants is investigated as a technique to effectively modify the Schottky barrier of NiGeSn/GeSn contacts. Secondary ion mass spectroscopy is employed to analyze dopant segregation and reveal its dependence on both the Sn content and biaxial layer strain.

Structural and optical properties of alumina passivated amorphous Si slanted columnar thin films during electrochemical Li-ion intercalation and deintercalation observed by in situ generalized spectroscopic ellipsometry

The authors report on the structural and optical property changes of alumina passivated amorphous Si slanted columnar thin films during electrochemical Li-ion intercalation and deintercalation determined by in situ generalized spectroscopic ellipsometry. The cyclic voltammetry investigations versus Li/Li+ are performed at a rate of 1 mV/s, while Mueller matrix generalized spectroscopic ellipsometry data are collected. Through a best-match model analysis utilizing the homogeneous biaxial layer approach, temporal anisotropic optical constants are obtained. The authors observe a strong anisotropic electrochromic response with maximum changes of ∼18% in the anisotropic refractive indices and ∼750% in the anisotropic extinction coefficients. Furthermore, the thin films reversibly expand and contract by ∼35%. A comparative analysis of the temporal optical constant response to the changes in overall optical anisotropy of the electrode reveals six transient regions throughout the Li-ion intercalation and deintercalation cycle of the highly ordered three-dimensional nanostructures. The transients correspond to electrochemical potential regions which show limited charge transfer, metalization or demetalization, and swelling or deswelling of the nanostructures. Furthermore, the electrochemical potential regions in which the transients are observed here are very similar to those previously reported for Li-ion intercalation and deintercalation of silicon nanowires using structural analysis techniques, where four distinct phases of Li-Si alloy formation were revealed. The authors find that at low Li contributions, swelling and deswelling occur preferentially along the slanted columns, while at high Li contributions, swelling and deswelling occur preferentially within the intercolumnar space.

Influence of geogrid on the drying shrinkage performance of concrete pavements

The aim of this study is to investigate the effect of geogrid on the drying shrinkage behaviour of concrete pavements. For this purpose, two categories of concrete specimens were prepared and tested by drying them within the controlled environmental conditions, for 56days. The first category of specimens included casting and testing nine concrete prism specimens having dimensions of 75×75×280mm. These specimens were divided into three groups. The first group included three unreinforced concrete prism specimens and taken as references. The second group consisted of three concrete prism specimens reinforced with a single biaxial geogrid layer located at 20mm from the top of specimen. The last three specimens (third group) were reinforced with a biaxial geogrid layer placed at 37.5mm from the top of specimen. The second category of specimens, which was suggested in this study to simulate the behaviour of concrete pavements, consisted of preparing and testing six concrete slab specimens. They had dimensions of 30×280×280mm. The specimens of this category were divided into two groups. The first group included three unreinforced concrete slab specimens (References). The second group included three concrete slab specimens reinforced with a single biaxial geogrid layer placed at 15mm from the top of specimen. The changes in the length of the prisms and the changes in the area of the slabs were measured and evaluated. Test results obtained illustrate that, under the controlled drying conditions, the geogrid can slightly reduce the drying shrinkage strains of the concrete pavements.

Field Instrumentation and Evaluation of Modular-Block MSE Walls with Secondary Geogrid Layers

AbstractMechanically stabilized earth (MSE) walls reinforced with geosynthetic have been used extensively in highway projects around the world. Typical vertical spacing of geosynthetic reinforcement used in the design of an MSE wall is 0.6 m. This large reinforcement spacing requires a high reinforcement connection strength and may result in wall-facing bulging in the practice. To alleviate such problems, use of secondary reinforcement between primary reinforcement layers was proposed. However, this idea was not verified in the field. In this study, three MSE wall sections reinforced with geogrid layers were constructed and monitored in the field: (1) an MSE wall section with uniaxial geogrid layers as primary and secondary reinforcement; (2) an MSE wall section with uniaxial geogrid layers as primary reinforcement and with biaxial geogrid layers as secondary reinforcement; and (3) an MSE wall section with uniaxial geogrid layers as primary reinforcement only (i.e., the control section). Earth pressure ce...

Bearing capacity of shallow strip foundation on geogrid-reinforced sand subjected to inclined load

Laboratory model test results for the ultimate bearing capacity of shallow strip foundation on multi-layered geogrid-reinforced dense and loose sand subjected to centric inclined load have been presented. The angle of friction for the dense sand and loose sand was 41 and 34 degrees, respectively. The tests have been conducted using biaxial geogrid layers as reinforcement with the embedment ratio (Df = depth of embedment of the foundation, B = width of foundation) varying as 0, 0.5, 1, and the load inclination (α) varying from 0 to 20° in 5° increments. The inclined load to the model foundation was applied by a specially designed machine. Based on the laboratory model test results, an empirical reduction factor has been developed to estimate the ultimate inclined load per unit area from the ultimate bearing capacity with vertical centric loading. The non-dimensional reduction factor is a function of Df, B, α, and df (df = distance between the ground surface and bottom geogrid layer).

New surface order reconstruction induced by electric field application in a nanoconfined HAN cell with a topological defect

In accordance with the 2D Landau–de Gennes tensorial formalism, we investigated the influence of an applied electric field E parallel to the defect line on the position and structure of a nematic line defect with topological charge M = − 1/2 in a hybrid alignment nematic cell with different cell gaps d. A new type of surface order reconstruction occurs in the cell as E is increased. Regardless of d, two biaxial layers can be achieved near the top and bottom substrates of the cell with different E values. This process involves double eigenvalue exchange across the cell. However, the structural transition processes vary for different d values.

Robust technique based on transition matrix method to electromagnetic characterisation of anisotropic material

This study presents a parameter retrieval technique based on the state space approach for the electromagnetic characterisation of biaxial anisotropic structures. First, the formulation of a 4 × 4 transition matrix method for the analysis of forward scattering problems is reviewed; then a procedure for the extraction of the constitutive tensor parameters of a biaxial anisotropic medium from the knowledge of reflection and transmission coefficients is implemented. In the proposed retrieval method, scattering parameters are employed for a plane wave incident normally and obliquely on a biaxial anisotropic slab. This characterisation algorithm is based on the state transition matrix and its properties in the biaxial anisotropic layers are presented as two theorems. In this method, it is not necessary to solve directly the wave equation in complex media and then apply the boundary conditions. To demonstrate the validity of the proposed method, the constitutive parameters of two non-dispersive and dispersive biaxial anisotropic slabs at microwave frequencies are retrieved. From the numerical results, one can find out that when the scattering parameters are combined with the properties of a state transition matrix, a robust technique is provided for the parameter retrieval of the anisotropic structures.