Effect Of Thickness Research Articles

Performance of channel shear connectors in steel frame with reinforced concrete infill walls

To examine the mechanical properties of channel shear connectors employed in steel frame with reinforced concrete infill wall (SRCW) structures, the improved push-out tests were performed on three specimens of channel shear connectors subjected to the monotonic and cyclic loading. This study investigated the influences of loading protocol and concrete strength on the mechanical behavior of channel shear connectors. After the refined finite element (EF) models of channel shear connectors were validated based on the push-out tests, a systematical parametric analysis was conducted to evaluate the effects of RC infill wall thickness, concrete strength, and channel dimensions on its shear strength of the channel shear connectors. In addition, this study also compared the accuracy of the CSA S16, AISC 360 and GB50017 design code in predicting the shear capacity of channel shear connectors in SRCW structures. The experimental results and parametric studies indicated that the current design equations inaccurately evaluate the shear capacity of channel shear connectors used in SRCW structures. Consequently, an alternative equation was developed to estimate the shear-resistant capacity of channel shear connectors in SRCW structures, which provided the desirable calculation precision for engineering design.

Towards high-strength electrolyte-supported solid oxide fuel cells

The functionality and structural reliability of electrolyte-supported solid oxide fuel cells depend crucially upon the load-bearing capability of the ceramic electrolyte. In this work, the effect of thickness on the mechanical strength of tape-casted 8 mol% yttria-stabilized zirconia electrolyte discs was investigated. Samples with 98 % relative density and 2–3 µm grain size fabricated with thicknesses between 75 µm and 360 µm were mechanically tested using an adapted biaxial bending test. Thin electrolytes with biaxial strength up to 1 GPa could be produced. The measured characteristic strengths ranged from σ0 = 940 MPa to σ0 = 520 MPa for thin and thick samples, respectively, yielding a common Weibull modulus of m = 6. A higher strength scaled with decreasing thickness, confirming the “size effect” as in many technical ceramics. The measured ionic conductivity was above 0.1 S/cm at 1000 °C, which is in good agreement with commercial or conventionally prepared electrolytes.

Experimental study on bond-slip behaviors of CFRP sheet-Q690 high strength steel plate considering the effect of CFRP sheet thickness and bonding length

With the increasing application of carbon fiber reinforced polymer (CFRP) in steel structure engineering, the bond-slip behavior between the two has attracted much attention. Firstly, 18 sets of CFRP sheet-Q690qD high-strength steel double strap shear specimens were fabricated considering the effects of CFRP sheet thicknesses and bond length. Then, static and fatigue tests were conducted on them. Subsequently, based on the 3D-DIC acquisition technology, the bond-slip curves were obtained using the smoothing method and the fitting method respectively Finally, the three key parameters of τmax, s1and sf in the bifurcated model at each working condition were obtained. The experimental results indicated that the bond length was positively correlated with the static load ultimate strength, while the thickness of the CFRP sheet had less effect on the ultimate strength. The fatigue life of the specimen with a bond length of 40 mm under equal stress ratio fatigue loading was much higher than that of the specimens with bond lengths of 60 mm and 80 mm. It was found that the fitting method had better stability and accuracy in fitting the bond-slip curves of CFRP sheet-Q690qD high-strength steel specimens. The accuracy of the fitting maximum bond load was above 80 %, which can provide a relevant basis for the subsequent numerical simulation calculation.

An Analytical Insight Into Stability Analysis of Unsaturated Multi‐Layered Slopes Subjected to Rainfall Infiltration

ABSTRACTSlopes in nature usually present layered characteristics, and its stability is susceptible to rainfall events. Considering that current analytical solutions are only suited to simulate the rainfall infiltration of double‐layered infinite unsaturated slopes, an analytical procedure is hence proposed in this study to tackle the consideration of multiple layers. The variable separation method and transfer matrix method are combined to derive the analytical solution of pore water pressure (PWP) for simulating rainfall infiltration in layered infinite unsaturated slopes. After having validated the proposed model and analytical solutions by comparing with existing literature and numerical simulation, the closed‐form solution of PWP is incorporated into the limit equilibrium for assessing slope stability. A three‐layer slope is selected as an example for further discussion. PWP distribution and factor of safety are calculated, considering the effects of saturated hydraulic conductivity and thickness of the upper layer, intensity of antecedent and subsequent rainfall, and varied soil unit weight along the depth. The slope stability subjected to rainfall effects is consistent with the variation of PWP. The proposed analytical solutions provide a simple and practical avenue for computing PWP distribution and evaluating the stability of multi‐layered slopes under rainfall conditions, which can also serve as a benchmark for numerical solutions.

Strategic implementation of variable-thickness insulation layers for stratospheric airships

Excessive heat transfer from photovoltaic systems to airship hulls poses a threat to flight safety. To address this issue, a theoretical model was developed that combines thermal, heat transfer, and optimization models for airships with variable-thickness insulation layers. The study investigates the daily thermal behavior of stratospheric airships, focusing on the effects of thermal conductivity and insulation thickness. To balance weight reduction with insulation effectiveness, temperature constraints were used, and insulation thickness was optimized across different sections of the airship using a simulated annealing algorithm (SAA). Results indicate that adjusting thermal conductivity and insulation thickness can mitigate overheating and overpressure, albeit with a reduced solar energy output. Notably, variable-thickness insulation achieved a 9.7 % weight reduction at 40°N latitude, enhancing both photovoltaic system design and insulation material selection for stratospheric airships.

Lateral stress induced blistering of tungsten exposed to deuterium plasma

Surface blistering on tungsten under deuterium plasma exposure has been well known and investigated intensively in the last decade. However, the mechanism of the blistering is still unclear. There have been mainly two different models proposed: the gas driven model and lateral stress model. In this work, we designed an experiment to address this issue. Tungsten disc samples were prepared using twin-jet electro-polishing. The specimens were under deuterium plasma exposure to study the thickness effect on the surface blistering. The results showed that blistering was rarely observed on the surface around the inner edge of the central perforation with thickness of ∼100–500 nm. The blisters started to appear on the surface when the thickness was about 10 μm. Both the number and size of the blisters increased further on the outer surface with further increase in thickness. This trend was not obvious as the thickness increased up to above 180 μm. The diffusion depth of D in this work was calculated to be 8.5 μm. These results affirmed the lateral stress model as the surface blistering mechanism.

Effect of ultra high-performance concrete thickness on the mechanical behavior of orthotropic steel bridge deck

Orthotropic steel bridge decks structures (OSBDs) have been widely used in long-span bridges to reduce the dead load of the bridge. However, over time, the asphalt wearing course of the bridge deck structure has shown many damages. Recently, ultra-high-performance concrete (UHPC) has been employed to repair and reinforce these structures. Therefore, this paper focuses on the effect of UHPC thickness on the mechanical behavior of the orthotropic deck. The five-point bending beam test model using the finite element method is used in this investigation to clarify the effect of UHPC thickness, the ratio of adhesion failure, and temperature on the mechanical behavior of the OSBDs. The UHPC thickness varies from 30 to 50 mm, the ratio of adhesion failure varies from 0.1 to 0.3, and the temperature changes from 30°C to 60°C. The results show that the presence of the UHPC layer significantly reduces the impact of adhesive layer damage and temperature on the behavior of the OSBDs

Numerical Analysis of 3D Unilateral Quasi-static Contact: Effect of Coating Thickness and Mechanical Properties

In this study, a numerical model for unilateral quasi-static contact between a rigid sphere and an elastic coating has been developed. The contact problem was solved using a numerical procedure based on the FFT technique, considering various coatings with different thicknesses and mechanical properties, implemented through a Matlab code. The model calculates the contact surface deformation and pressure field through a double iteration process. The first iteration solves the contact problem for a given indenter penetration, while the second iteration refines this penetration by minimizing the difference between the fixed and calculated loads. To achieve this, influence coefficients are derived from the elasto-static equations using the Papkovich-Neuber potentials. The study discusses the influence of coating thickness and friction coefficient value on the tribological behavior of the coating. The results indicate that contact pressure increases (ranging from 1.9 to 2.5) as the coating becomes thicker or more rigid (0.02 mm to 0.2 mm). Additionally, the tribological behavior of the coated surface is affected by the coating's thickness, hardness, and friction coefficient value. Importantly, this model demonstrates versatility by being applicable to both smooth and rough surfaces.

Does it affect the live birth rates to have a maximum endometrial thickness of 7, 8, or 9 mm in in-vitro fertilization-embryo transfer cycles?

To assess the effect of endometrial thickness (EMT) on live birth rates (LBR) in women with endometrial lining between 7.0-9.9 mm. This retrospective cohort study included women who underwent fresh and frozen embryo transfers between 2008 and 2018, grouped according to their maximum EMT; group 1, 7.0-7.9 mm; group 2, 8.0-8.9 mm; and group 3, 9.0-9.9 mm and underwent blastocyst transfer. The study included 7,091 in-vitro fertilization cycles: 1,385 in group 1, 3,000 in group 2, and 2,706 in group 3. The combined LBR was 22.2%. The mean age of women at oocyte retrieval day was 36.7±4.5 years. There was no difference in female age at oocyte retrieval or in the quality of embryos transferred between the three groups. Group 1 had more diagnoses of diminished ovarian reserve (25.8% vs. 19.5% and 19.1%; p<0.001) and less male factor infertility compared with group 2 and 3, respectively (25.0% vs. 28.8% and 28.5%; P=0.024). LBR was higher with increasing endometrial thickness, group 2 vs. group 1 (22.0% vs. 17.4%; P=0.0004), group 3 vs. group 1 (25.0% vs. 17.2%; p<0.001), and group 3 vs. group 2 (25.0% vs. 22.0%; P=0.008). After controlling for confounding factors, these three groups did not differ in LBR (group 1 vs. group 2, odds ratio [OR], 1.08; 95% confidence interval [CI], 0.83-1.4; P=0.54 and group 1 vs. group 3, OR, 1.16; 95% CI, 0.90-1.51; P=0.24). Live birth rates in women with endometrial thickness between 7.0-9.9 mm were not affected by different cut-offs when blastocyst transfer was performed.

Role of surface roughness in determining surface energy and magnetic properties of Fe80Ce20 films during thermal processing on Si(100) and glass substrates

In this study, Fe80Ce20 films were deposited on Si(100) and glass substrates using sputtering in a high-vacuum environment and subsequently heat-treated in a vacuum annealing furnace. The films, with thicknesses ranging from 10 nm to 50 nm, were annealed at temperatures of 100 °C, 200 °C, and 300 °C. The objective was to investigate the effects of film thickness and annealing temperature on the structural, surface energy, and magnetic properties of the material. X-ray diffraction (XRD) analysis confirmed the crystalline nature of both Si(100)/Fe80Ce20 and Glass/Fe80Ce20 films. Atomic force microscopy (AFM) revealed a smooth film surface that became rougher after annealing. Contact angle measurements indicated hydrophilic properties, with the highest surface energy observed in the as-deposited films due to a higher density of defects and grain boundaries. The hysteresis loop demonstrated exceptional soft magnetic properties and a high saturation magnetization (Ms) of approximately 2000 emu/cm³. Annealing at 100 °C altered the magnetic domain structure from a striped labyrinthine configuration to an aligned pattern. At higher annealing temperatures, the films exhibited grain growth, increased surface roughness, and new grain formation. Following annealing, the grains in the Fe80Ce20 films became larger, surface roughness increased, and the water contact angle increased, rendering the films more hydrophobic. The as-deposited films displayed the highest surface energy due to the high density of defects and grain boundaries. Increased surface roughness led to more grain boundary defects and irregularities, which served as pinning points for magnetic domain walls, thus increasing coercivity (Hc). Rough surfaces induced local stress fields, increased magnetic anisotropy, and decreased saturation magnetization. Thermal perturbations from higher annealing temperatures further disrupted the alignment of the magnetic moments, leading to a reduction in saturation magnetization.

Deep learning-driven predictive tools for damage prediction and optimization in composite hydrogen storage tanks

This research presents a comprehensive framework for predicting the damage in lightweight composite high-pressure hydrogen storage tanks and optimizes their design to prevent failure. By integrating advanced analytical methods, numerical analysis, and deep learning techniques, we introduced a novel approach to enhance design optimization and damage prediction. The framework employs the 3D elasticity anisotropy theory to predict mechanical performance, incorporating failure criteria for accurate damage analysis. A parametric study was conducted to examine the effects of thickness, pressure, and diameter on the behavior of the tank. The analytical results were compared against finite element analysis using the WoundSim software, underscoring the significance of the modeling assumptions. Furthermore, we developed a new framework that combines deep neural networks with differential evolution optimization (DNN-DEO) to predict stress and damage in composite pressure vessels while identifying the optimal design parameters (pressure, radius, and thickness) to minimize failure risks and maintain high performance. A graphical user interface (GUI) was also designed to automate calculations and predictions, providing an intuitive tool for users. This integrated approach offers a powerful solution for optimizing the design and operation of lightweight composite hydrogen storage tanks, ensuring the reliability and efficiency of hydrogen storage systems.

Research on a Honeycomb Structure for Pyroshock Isolation at the Spacecraft–Rocket Interface

Honeycomb is a splendid kind of structure for aerospace engineering with the advantages of light weight, good shock absorption, and good structural stability. This article aims to provide methods to isolate Pyroshocks based on a honeycomb structure and guarantee the safety of such equipment against a high-frequency shock response. According to stress wave theory, an equation for stress wave transmittance of the honeycomb structure is derived considering the effect of cell wall length and thickness, where desirable honeycomb parameters are obtained. The complexity of the transfer path of the honeycomb structure is exploited to build the spacecraft–rocket interface, which could increase the impedance of the stress wave dramatically. Both finite element analysis and experiments are carried out to validate the shock isolation strategies. The influence of parameters, such as cell wall length and the thickness of the stainless-steel honeycomb, on the isolation performance is analyzed. It is revealed that the honeycomb structure has a significant effect on Pyroshock isolation performance when the wall length of the honeycomb cell is 8 mm and the thickness of the cell is 0.1 mm.

Evaluation of insulation effectiveness for thermal comfort in summers: experimental and CFD numerical study

We evaluate the thermal performance of PUF-insulation boards embedded in the roof of an office-sized room. Two rooms were constructed: one with and the other without insulation. The thermal comfort was evaluated by performing an experimental study according to ANSI/ASHRAE Standard 55-2017. The inside air temperature, humidity, wall and ceiling temperatures, air velocities and thermal flux were measured for the summer April–June 2023. Using these measurements, the PMV and PPD values were computed. The effectiveness of the insulation material with regard to thermal comfort is judged by the reduction in values of these indices. During a typical day, a reduction of around 30% is achieved just by adding the insulation. Nusselt number correlations are proposed to predict the convective heat transfer from the walls. Detailed CFD simulations were performed and a parametric study to understand the effect of insulation thickness, wall insulation, roof thickness and room dimensions on thermal comfort was undertaken.

Crashworthiness analysis of hierarchically reinforced double-square tubes under axial impact

Two strategies are proposed to design new hierarchically reinforced double-square tubes (HRDST). Strategy A: adding triangles from inside to outside in one direction. Strategy B: adding triangles along both the outer and inner quadrilateral directions at the same time. Their crashworthiness analyses are carried out under the conditions of the same wall thickness and the same mass. The results show that the proposed double square tubes, combined with the gradient hierarchical design, can effectively improve the crashworthiness of the structure under both conditions. The improvement of strategy B is more significant than that of strategy A. The energy absorption (EA), specific energy absorption (SEA), and crushing force efficiency (CFE) and initial peak crush force (IPCF) of HRDSTB-3 are improved by 2343.87%, 493.17%, 573.74% and 262.73%, respectively, under the same wall thickness. The EA, SEA, CFE of HRDSTB-3 also increased by 111.23%, 111.23%, and 226.34%, respectively, for the same mass, while the IPCF decreased by 35.27%. The parametric study shows that the effect of wall thickness on structural crashworthiness is significant, but the rate of increase between two adjacent wall thicknesses decreases as the wall thickness increases. The inner and outer edge length ratios (k) also have a substantial effect on structural crashworthiness, with SEA and CFE being 24.42% and 23.47% higher for k = 5/12 compared to k = 8/12 for HRDSTA-3, and 29.24% and 27.55% higher for k = 4/12 compared to k = 8/12 for HRDSTB-3. Finally, comparing HRDSTA-3 and HRDSTB-3 with other square-layered multicellular designs, the results show that the two designs proposed in this paper, combining double square tubes with gradient hierarchies, exhibit better crashworthiness. Compared with MSTL2-2, the SEA of HRDSTA-3 and HRDSTB-3 are 27.98% and 33.01% higher, respectively, and the CFE is 27.86% and 32.96% higher, respectively.

Assessment of ply thickness and aluminum foils interleaving on the impact response of CFRP composites designed for cryogenic pressure vessels

Carbon fiber reinforced polymer (CFRP) proved to be the best choice to produce cryogenic pressure vessels coupling a reduced weight with superior mechanical performance. Despite this, CFRPs are prone to fuel leakage due to interconnected matrix cracks resulting from mechanical and thermal stresses. Two strategies were combined in this work to reduce fuel permeability, i.e., increase of plies number and metallic film interleaving, evaluating the cryogenic impact response of these new configurations. At first, the only ply thickness effect was assessed and the hybrid sandwich-like (SL) configuration with traditional CFRP (RC) skins and a thin-ply (TP) core displayed impact and residual flexural properties close to RC ones. Then, the effect of aluminum foils interleaving was investigated, and the interleaved SL configuration displayed higher residual flexural properties than interleaved RC for all temperatures, e.g., the residual flexural strength was 30.3 % higher at room temperature and 14.6 % higher at −70 °C, respectively.

Analysis of operation regulation on delay time in long-distance heating pipe systems for practical engineering

The distribution area of the district heating network (DHN) is extensive, and there are inherent time delays and thermal losses in the process of heat transfer through heating pipes. The delay in heat transfer within long-distance heating pipes may result in inadequate heat supply to end-users or excessive energy consumption at the heat source. Therefore, this paper presents a quasi-dynamic model for calculating the transmission delay time in the long-distance heating pipeline. And the model is validated through the measured values obtained from a heating pipeline. The influencing factors of delay time are further discussed, including operating parameters, pipe structure parameters and thermal insulator thickness. Additionally, the impact of pipe delay time in practical engineering is analyzed. In practical engineering, the transmission delay time varies when the pipe structural or operational parameters differ, even under the same outdoor temperature change. The change in inlet water temperature and mass flow rate can impact the change rate of outlet water temperature, thereby influencing the delay time. Furthermore, the delay time exhibited an increase with pipe length, diameter, and thermal insulator thickness; however, the effect of thermal insulator thickness on it was minimal. When the inlet water temperature rose or dropped by 5℃, the delay time grew by more 70 % per 1 km pipe length, about 40 % per 100 mm diameter and less 2 % per 100 mm thermal insulator thickness, respectively.

Surface plasmon polariton excitation and propagation in metal tripod systems

Through the activation of a planar gaseous medium consisting of four-level tripod atoms, our approach provides a mechanism to generate the Surface Plasmon Polariton (SPP). We investigate a three-layer structure in which the bottom layer is composed of atoms arranged in a tripod configuration, a metal film is layered in the middle, and a transparent layer of either air or vacuum resides on top. The bottom layer facilitates SPP excitation via amplification in the atom arrangement, caused by three laser beams: control, weak probe, and signal. The electromagnetically induced transparency effect, which can be seen in atoms, compensates for the momentum difference between light and SPP. We can coherently change SPP propagation length by altering control field strength, resonance, and off-resonant detuning. SPP optical gain power, propagation length, penetration depth, and metal thickness effects are also examined. Our method to generate SPPs may find use in lithography, sensors, polarizers, along with photodetectors.

Effects of thickness, temperature and substrate on phonon anisotropy in layered Ta2NiSe5

Anisotropy in crystal structure has provided a new degree of freedom to tune the physical and photoelectric properties of low-symmetrical materials, enabling the anisotropic band structure and polarization-resolved applications. Thus, the identification and control on the anisotropy is of great importance for the development of polarization-integrated devices. In this work, we introduce a promising two-dimensional (2D) dimetal chalcogenide Ta2NiSe5 with strong in-plane anisotropic structure and explore the effects of thickness, temperature and substrate on its in-plane anisotropy via an angle-resolved polarized Raman spectra. It is shown that the Raman mode softens with increasing temperature, revealing the anharmonic phonon properties of the Ta2NiSe5 flakes. We found that the anisotropy of phonon vibration is strongly related with the thickness, temperature and used substrate, which is more obvious at thinner samples, higher temperature and opaque silicon substrate compared to sapphire and suspended conditions. This work first reveals the influence factor on the anisotropy of phonon mode, which will guide the fundamental research of anisotropic physics and experimental design for the angle-resolved electronics.

Thickness dependence and crystallization properties of amorphous GeTe thin films on silicon dioxide

Radio frequency magnetron sputtering was used to prepare the amorphous GeTe thin films on silicon dioxide and the thickness effects on the crystallization behavior were investigated. With the film thickness reducing, the crystallization temperature, crystallization activation energy, amorphous and crystalline resistance increase remarkably, indicating the great improvement in thermal stability and power consumption. Ozawa’s model was used to estimate the crystallization kinetics of GeTe thin films, it shows that nucleation and grain growth occur simultaneously, and grain growth dominates ultimately. XRD analysis demonstrated that the grain size can be reduced and the crystallization process of GeTe thin film can be inhibited with the film thickness decreasing. Furthermore, the thinner film has smaller resistance drift index and surface roughness, which are beneficial to improve the reliability of storage device. T-type phase change memory devices based on 25 nm GeTe thin film were fabricated by 0.13 μm CMOS technology, and the current–voltage and resistance-voltage characteristics demonstrate the excellent electrical performance, including the fast resistance switching between SET and RESET processes, low threshold current and voltage. All the results proved the strong dependency relationships between the crystallization properties and film thickness of GeTe thin film, which paves the way for developing high-density phase change memory in the fields of big data and artificial intelligence.

Epitaxial growth of quasi-2D van der Waals ferromagnets on crystalline substrates

Intrinsic magnetism in van der Waals materials has instigated interest in exploring magnetism in the 2D limit for potential applications in spintronics and also in understanding novel control of 2D magnetism via variation of layer thickness, gate tunability and magnetoelectric effects. The chromium telluride (CrxTey) family is an interesting subsection of ferromagnetic materials with highTCvalues, also presenting diverse stoichiometry arising from self-intercalation of Cr. Apart from the layered CrTe2system, the other non-layered CrxTeycompounds also offer exceptional magnetic properties, and a novel growth technique to grow thin films of these non-layered compounds offers exciting possibilities for ultra-thin spin-based electronics and magnetic sensors. In this work, we discuss the role of crystalline substrates in chemical vapor deposition growth of non-layered 2D ferromagnets, where the crystal symmetry of the substrate as well as the misfit and strain are the key players governing the growth mechanism of ultra-thin Cr5Te8, a non-layered ferromagnet. The magnetic studies of the as-grown Cr5Te8reveal the signatures of co-existing soft and hard ferromagnetic phases, which makes this system an intriguing system to search for emergent topological phases, such as magnetic skyrmions.