Thickness Of Composite Layer Research Articles

Quantitative analysis of failure performance uncertainty based on multiscale mechanical analysis of PEMFCs’ C/C composite bipolar plates

In order to quantify the failure performance of PEMFCs’ C/C composite bipolar plates (BPs) under considering the uncertainty in multiscale sizes and loads, the failure probability function (FPF) of BPs at cold start is estimated. A three-stage multiscale simulation method is proposed for mechanical behavior analysis of multi-component heterogeneous composites. And the efficient estimation of FPF for C/C composite BPs is achieved via the proposed multiscale simulation method and decoupling sparse integration method, in which the unified density weight is constructed to decouple the double-loop framework of analyzing FPF, thereby reducing the computational complexity. Results indicate that the dangerous positions of BPs are around the gas flow channels and bolt holes. And the dangerous components are the carbon matrix and the interface between the matrix and fiber. The radius of elliptical fibers affects the distribution of failure factors on microscopic components, thereby affecting the variation of failure probability with fiber sizes significantly. The distribution parameter of composite layer thickness in BPs has a significant effect on structural safety, and the FPF result can be used to effectively guide the design of structure. Therefore, the proposed method is of great significance for guiding the rapid parameter design of composite BPs.

Polymer Composite Cladding for Selective Frequency Filtration: An Experimental and Modeling Study

Laser selective frequency filtering is currently performed using expensive, heavy, and bulky (millimeters in thickness) ceramic composite claddings around the laser rod, which limits the miniaturization and transportability of the laser. The cladding absorbs undesired spontaneous emissions and reflects the desired wavelength of the "pump" diode. As an improved alternative for the cladding on, say, a diode-pumped solid-state Nd:YAG laser rod, we investigate a spray-coated polymer composite cladding (micrometers in thickness). The polymer composite cladding is easier to process and lighter and has a much smaller volume vs. traditional ceramic composite claddings. The approach is demonstrated on spray-coated glass slides, where cubic samaria (Sm2O3) particles are used as the filler in the polymer composite cladding. The rationale for using samaria as the filler in the composite is its absorption near the laser spontaneous emission wavelength (i.e., 1064 nm) and high reflectivity at the incident pump wavelength (i.e., 808 nm). The addition of a second polymer composite layer loaded with alumina particles enables reduction of the samaria composite layer thickness. The Kubelka-Munk model is shown to successfully predict the experimentally measured optical performance of single and bilayer claddings, making it a reliable design tool for multilayer claddings.

Effects of drawing speed on microstructure and properties of Cu-Ni-Si alloy clad AA8030 alloy composites prepared by continuous casting composite technology

The Cu-Ni-Si alloy clad AA8030 alloy rod was prepared by continuous casting composite technology with gradient-varying drawing speeds, and the influences of drawing speed on the casting quality and microstructure of Cu-Ni-Si alloy clad AA8030 alloy rod were systematically studied. The drawing speed at which satisfactory continuous casting quality could be obtained was 90–120 mm/min. Meanwhile, axial columnar grains favorable for subsequent plastic processing were obtained, although the angle between columnar grains and axial direction increased with the increases of drawing speed. Moreover, with the drawing speed increasing from 90 mm/min to 120 mm/min, the thickness of composite interfacial layers was significantly increased, and the morphology of interfacial phases was gradually changed. The Cu-Ni-Si alloy cladding layer was cut from the composite to perform solution and aging experiments. The results showed that the solid solution effect of the as-cast Cu-Ni-Si alloy was consistent with that of the solution-treated Cu-Ni-Si alloy because of the rapid cooling characteristics of continuous casting composite technology, which solved the problem that the composite rod could not be solution treated as a whole due to the lower melting point of the Al core.

Aero-Structural Comprehensive Nonprobabilistic Reliability-Based Optimization Method for High Aspect Ratio Wings

An aero-structural comprehensive reliability-based optimization method is proposed to construct the optimization framework of designing the high aspect ratio wing. There are three parts included in this method. 1) The ideal cruising shape is obtained by optimizing the geometrical parameters in the cruising conditions, where only the aerodynamic shape optimization is involved and the structural deformation is not considered. 2) The jig-shape optimization method is presented, where the aerodynamic performance of the wing structure with deformation is improved by adjusting the twist angle along the span direction to make sure that the shape with the aeroelastic deformation approaches the ideal cruising shape. 3) A nonprobabilistic reliability-based structural optimization is conducted by updating the thickness of composite layer, where the dispersion of mechanical properties of composite materials is considered and a nonprobabilistic reliability index according to strength and stiffness constraints is established. The global stiffness of the wing structure is changed after jig-shape optimization and structural optimization, and the jig-shape and structural scheme are modified alternately. The previously mentioned process needs to be repeated until the changes in the jig-shape and structural scheme in the iterations can be ignored. Finally, the effectiveness of this method has been verified through the numerical example followed by some conclusions.

Influence of Layer Thickness and Shade on the Transmission of Light through Contemporary Resin Composites.

Material-dependent parameters have an important impact on the efficiency of light polymerization. The present in vitro study aimed to investigate the influence of the increment thickness and shade of nano- and nanohybrid resin composites on the transmission of curing light. Three contemporary resin composites were evaluated: Tetric EvoCeram® (TEC); Venus Diamond® (VD); and Filtek Supreme XTE® (FS XTE). Light transmission (LT) was recorded in accordance with the sample thickness (0.5 to 2.7 mm) and the shade. Polymerized samples were irradiated for 10 s each using the high-power LED curing light Celalux 2 (1900 mW/cm2). LT was simultaneously recorded using the MARC Patient Simulator (MARC-PS). LT was strongly influenced by the composite layer thickness. For 0.5 mm-thick samples, a mean power density of 735 mW/cm2 was recorded at the bottom side. For the 2.7 mm samples, a mean power density of 107 mW/cm2 was measured. Only LT was markedly reduced in the case of darker shades. From A1 to A4, LT decreased by 39.3% for FS XTE and 50.8% for TEC. Dentin shades of FS XTE and TEC (A2, A4) showed the lowest LT. The thickness and shade of resin composite increments strongly influences the transmission of curing light. More precise information about these parameters should be included in the manufacture manual.

Probabilistic buckling assessment and reliability of fiber-metal laminate, composite and aluminum cylindrical panels under compression with load and fabrication uncertainties

The objective of this article is to study the buckling behavior and reliability of fiber metal laminated (FML), composite and aluminum cylindrical panels under uniaxial compression taking into account fabrication and loading uncertainties. A 3D finite element modeling with ANSYS software has been implemented for this purpose. The panels are discretized using shell elements and the eigenvalue buckling analysis is conducted for the prediction of elastic buckling. The influences of load and fabrication uncertainties on the buckling load factor are studied with probabilistic analyses and the reliability of the panels is calculated. It is found that the thickness of aluminum layers is the most significant uncertain variable for the critical buckling load factor of FML panels, whereas the fiber misalignment angle of their composite layers is insignificant. As the metal volume fraction decreases, the sensitivity of the elastic buckling load factor to variations of the axial load distribution is reduced whereas its sensitivity to variations of the thickness of composite layers is increased. Consequently, the metal volume fraction is an important design parameter for the uncertain buckling behavior of the panels.

Flexural capacity and serviceability evaluation on seawater sea-sand concrete beams reinforced by BFRP bars and TRE composite in the dry-wet environment

To promote the durability and serviceability of offshore structures, the bearing capacity and serviceability of BFRP-reinforced seawater sea-sand concrete (SWSSC) beams with textile reinforced ECC (TRE) to retard deformation and cracking under chloride dry-wet cycles were investigated. A total of a BFRP-reinforced SWSSC beam and nine TRE composite beams were designed. The dry-wet cycles, thickness, fabrication method and shape of TRE composite layer as factors the on the bearing capacity, deflection and crack behavior, curvature and ductility of beams with TRE composite were analyzed. TRE composite layer still can visibly increase the cracking moment of BFRP-reinforced SWSSC beams even in the dry-wet conditions, but the improvement effect on the ultimate moment was noteless. The bearing moments of composite beams increased with the TRE thickness and the dry-wet cycles. The failure modes for composite beams with the same reinforced radio of FRP bars under dry-wet environment changed from failure in shear cross zone to failure in pure bending zone with the increase of the thickness of TRE composite layer. The development of deformation and cracks for beams with TRE composite was significantly distinct from that for BFRP-reinforced SWSSC beams, attributed to the bonding properties of the composite layer to concrete, which with the TRE composite subjected to service moments can be judged by the curvature of 0.00375/d, below the curvature of 0.005/d. The fine cracks in TRE composite beams developed sequentially throughout the pure bending of beams. The dry-wet environment can reduce the deflection by increasing the stiffness of beams. Under service moment, the neutral axis height of TRE composite beam was clearly superior to that of BFRP-reinforced SWSSC beam. The variation trend of ductility index on energy and deformation was different. And the ductility of TRE composite beams declined as the increasing dry-wet cycles, regardless of the energy or deformation.

On resonance behavior of sandwich conical shell

Forced vibration is one of the essential behaviors of structures to predict the mechanical properties of various systems. Magneto-rheological (MR) or electro-rheological (ER) materials, due to many possible control-based applications, have gotten much attention in the oscillating system. Thus, in the present work, for the first time, the forced vibration of a conical shell made of three layers with an electrorheological (ER) core and reinforced composite with GPLs is investigated. The formulations are derived from the principle of Hamilton. With the aid of compatibility equations, the interfaces between the core and composite face sheets are simulated. The coupled hyperbolic differential quadrature method (HDQM) and Runge-Kutta solution procedure is employed to solve the coupled governing equations of the current system. The computational method’s accuracy is confirmed by comparing computed results with those available in the literature. The results show that the number, weight fraction, thickness, and pattern of composite layers, electric/magnetic field, and geometry of the conical panel have an important role in the central deflection and phase plot of the current sandwich structure.

Research on the permanent deformation mechanism and dynamic meso-mechanical response of porous asphalt mixture composite structure using the discrete element method

This study proposed a heterogeneous 3D virtual rutting model to investigate the rutting evolution mechanism and the dynamic meso-mechanical response of a porous asphalt mixture composite structure. The 3D virtual rutting test model incorporated a three-phase asphalt mastic-aggregate-airvoids system with grain size distribution and genuine aggregate morphology. Innovative algorithms were developed for cyclic rolling loading to reflect repetitive wheel loading. In contrast to the indoor rutting tests, the 3D virtual rutting tests exhibited greater rutting deformation and weaker dynamic stability in the range of 3.16%–10.17% and 2.65%–11.77%, respectively. Shear forces were predominant in the virtual rutting tests. As the porous asphalt mixture composite structure's surface layer thickness increased, the shear contact force increased and the maximum parallel-bond (PB) contact force diminished. The 3D virtual rutting test model was demonstrated to be feasible for simulating rutting deformation and dynamic meso-structural responses in porous asphalt mixtures with cyclic rolling loading algorithms.

Calibrating equations to predict the compressive strength of FRP-Confined columns using optimized neural network model

A procedure based on machine learning algorithms is used to develop design equations for the compressive strength of FRP confined columns. The procedure involved training and optimizing an Artificial Neural Network (ANN), and using the parametric variation of each input of the ANN to investigate nonlinear relationships between input parameters and model output. Results of the parametric study were illustrated using Partial Dependence Plots (PDP), and a polynomial regression model (PRM) was calibrated to offer a simple equation to calculate compressive strength of columns confined with FRP sheets. The ANN and PRM developed using this method provided more accurate and precise estimates of compressive strength of retrofitted columns than other models found in the literature. Moreover, investigating the relationships between each input variable and the output of the ANN model and coupling effects between pairs of input variables on the output of the ANN model using Partial Dependent and contour plots revealed that confined compressive strength was insensitive to the elastic modulus of the composite layers with the thicknesses of 2 mm or less. A new equation was recalibrated for specimens with composite layer thickness greater than 2 mm, which provided very accurate estimates of confined compressive strength for this empirical subset.

Investigating the deformation behavior of hot-pressed Ti/Al/Ti laminated composite

In this paper, the deformation behavior of Ti/Al/Ti composite fabricated by the hot-pressing process was investigated by simulation and experimental analyses. Furthermore, the elastic properties of laminated composites were predicted by using different representative volume elements (RVEs) subjected to compression and tension. The SEM images displayed well-bonded straight interfaces. Also, XRD and EDS analyses revealed that TiAl3 was the only intermetallic compound that grew at the Ti/Al interfaces. The simulation results showed that stress concentration and strain localization existed at the interfaces during hot compression. In addition, the elastic behavior of simulated RVEs agreed relatively well with the experimentally-obtained values. Nevertheless, the predicted values of effective elastic constants of large RVE were consistent with the experimental values. This is due to the actual thickness, volume fraction, and stacking order of composite layers.

Performance-based design and manufacturing of filament wound Type-4 cylinders for compressed gas storage

Filament wound type-4 cylinders are widely used in automotive applications for the storage of compressed gases. The performance of the storage cylinders critically depends on their manufacturing parameters. These paramters include the material properties of the reinforcement and matrix material, the number of fiber spools used during winding, the fiber bandwidth, the initial fiber band volume fraction, the mandrel geometry, the winding sequence, and the composite layer thickness distribution. An interim link between the critical parameters, the composite thickness distribution and the amount of fiber and resin consumed for winding a type-4 composite vessel has been established using an analytical model in this study. The developed model is validated by manufacturing the cylinder and comparing the theoretical and experimental results. The composite layer distribution across the entire geometry of the vessel is included into an FEA model to predict the burst pressure and weight of the obtained type-4 cylinder with greater precision. The given study can be used to design low-cost high burst performing type-4 composite structures with significant weight reduction.

Dynamics and Strength of Metal-Composite Cylinders on Internal Explosion Against the Thickness and Properties of Metallic and Composite Layers. Part 2. Numerical Simulation of Thick-Walled Cylinders and Effect of Stress Components on Strength*

Dynamics and Strength of Metal-Composite Cylinders on Internal Explosion Against the Thickness and Properties of Metallic and Composite Layers. Part 2. Numerical Simulation of Thick-Walled Cylinders and Effect of Stress Components on Strength*

Dynamics and Strength of Metal-Composite Cylinders on Internal Explosion Against the Thickness and Properties of Metallic and Composite Layers. Part 1. Numerical Simulation of Thin- and Medium-Thickness Cylinders

Dynamics and Strength of Metal-Composite Cylinders on Internal Explosion Against the Thickness and Properties of Metallic and Composite Layers. Part 1. Numerical Simulation of Thin- and Medium-Thickness Cylinders

Numerical Investigation of the Anti-infiltration and Anti-Erosion Performance of Composite Layers Mixed With Polyacrylamide and Basalt Fibre for the Protection of Silt Subgrade Slopes

In view of the failure characteristics of rainfall erosion and imbricate layered sliding of silt subgrade slopes, this paper proposes a slope surface protection technology that is a composite protection layer that combines basalt fibre for reinforcing soil and polyacrylamide for solidifying soil. The anti-infiltration and anti-erosion performances of these proposed composite layers were systematically investigated through the finite element and discrete element numerical simulation methods. Based on the optimum proportions of polyacrylamide and basalt fibre found in a series of mechanical experiments, Geo-studio software was used to simulate numerical tests of rainfall infiltration of the silt subgrade slope, and the variation laws of volumetric water content and pore water pressure at the characteristic points and the selected sections of the slope were discussed. In addition, the PFC2D particle flow program was used to develop numerical tests on the slope erosion process of the composite layers and to analyze the degree of soil erosion during the process. The influences of layer thickness on infiltration and erosion were considered. In conclusion, the results indicate that the composite layers can effectively improve the anti-infiltration and anti-erosion performances of the silt subgrade slope. This highlights that the thickness of composite layers mixed with basalt fibre can satisfy the design parameter requirements for anti-erosion performance.

Challenges toward applying UHTC-based composite coating on graphite substrate by spark plasma sintering

In this study, the UHTC-based composite layers where applied on the graphite substrates using SPS method to protect them against ablation. The protective layers had some defects and problems such as crack, fracture, separation, melting, and weak adhesion to the substrate. Several factors such as the thickness of composite layer, the number of protective layers, the SPS conditions (temperature, applied pressure, soaking time and mold), the chemical composition of the layers, the type of the substrate and the mismatch between the thermal expansion coefficients of the substrate and the applied layer(s) affected the quality and connection of the protective layer to the graphite substrate. The amount of additive materials influenced the melting phenomenon in the composite layer; for example, further MoSi2 in the layer led to more melting. The mismatch between the thermal expansion coefficients of the graphite substrate and the composite layer caused stresses during the cooling step, which resulted in cracks in the applied layer. Hence, proximity in the thermal expansion coefficients seems to be necessary for the formation of an acceptable adhesion between the layer and the substrate.

Analysis of composite pressure vessel and composite overwrapped pressure vessel by analytical and finite elemental approach

Finite element analysis (FEA) was used to investigate the effects of different metal thicknesses on burst pressure and deformation of composite over wrapped pressure vessel (COPV) under fluid force. Low carbon steel and Carbon- epoxy had been selected as the materials for COPV. A constant fiber orientation angle had been considered. FEA results had been compared and found to be in good agreement with those obtained from analytical equations to validate the final element approach. Analysis had been extended to pure composite pressure vessels and COPV varying thickness of metal and keeping constant composite layer thickness to study the overwrapping effect. The metal layer was varied from 1 to 3 mm keeping constant composite layer thickness (3 mm). The COPV exhibited bursting strength greater than that of composite vessels considered for the analysis. The results showed that COPV with equal metal and composite layer offered the greatest bursting strength.

Prediction of composite layer thickness for Type III hydrogen pressure vessel at the dome part

A Type III hydrogen pressure vessel composed of an aluminum liner and composite layers was analyzed, and the rapidly varying thickness of composite layers at the dome part was precisely estimated. As each helical winding angle leads to a different coverage area on a liner and hoop winding controls the composite thickness at the junction of the cylinder and dome parts, the thickness between the cylinder and dome parts varies considerably. The filament overhead induces errors in the dome thickness prediction and affects finite element modeling. Here, the effect of geometric changes in composite layers on the filament overhead was estimated, and the composite thickness of a Type III hydrogen pressure vessel at the dome part was analytically predicted. The effect of precise thickness prediction at the junction and dome parts was verified using a finite element analysis.

Layer thickness optimization of ceramic composite for body armor by considering volume, weight, and cost

This study investigates visualization of optimized layer thickness with a ternary diagram by considering Volume, Weight, and Cost priorities to determine the composite structure of alternative ceramics to use in body armor application by using the Digital Logic Method (DLM). Three criterion priorities (volume, weight, cost) have been investigated to help designers decide on optimum ceramic material for their applications. Alumina (Al2O3), silicon carbide (SiC), silicon nitride (Si3N4), and boron carbide (B4C) were analyzed and ranked to decide for material selection based on priorities. The analysis results showed that silicon nitride (Si3N4) had the maximum performance index (PI) point (80.0) based on the volume priority. On the other hand, while boron carbide (B4C) had the maximum PI point (76.4) in terms of the weight priority, alumina (Al2O3) was determined to be the best material according to the cost priority. PI point of alumina (Al2O3) was calculated as 100. A ternary diagram was developed for decision-makers to visualize material selection performances. The optimization of the ceramic composite layer thickness of the alternative ceramic materials is visualized by considering three criteria.

Штамповая оснастка и инструмент для изготовления трехслойных плоских кольцевых деталей с композитными материалами

The results of designing die equipment and special tool through separate die operations for manufacturing sandwich flat ring parts with the middle base metal layer and periphery elastic layers with increased composite thickness are shown. Efficient geometrical dimensions and a tool shape ensuring qualitative manufacturing parts mentioned and extension of technological potentialities of separating operations for their manufacturing, in particular, for design options with the increased thickness of periphery elastic composite layers are optimized experimentally.