Uniform Load Research Articles

Influence of interstitial fluid pressure, porosity, loading magnitude, and anisotropy in cortical bone adaptation

Adaptive elasticity in cortical bone has traditionally been modeled using Strain Energy Density (SED). Recent studies have highlighted the importance of interstitial fluid in bone adaptation, yet no research has quantified the role of interstitial fluid pressure and its effects, specifically incorporating both SED and interstitial fluid pressure in the adaptation process. This study introduces a novel formulation combining theory of porous media and theory of adaptive elasticity that considers both SED and interstitial fluid’s pressure in cortical bone adaptation. The formulation is solved using ANSYS Fluent and a MATLAB script, and sensitivity analyses were conducted, analyzing various porosities, loading magnitudes, anisotropic properties of cortical bone, and involvement coefficients of interstitial fluid’s pressure. This study reveals that bones with different vascular porosities (PV) tend to achieve similar density distributions under uniform loading over time. This highlights the significant role of interstitial fluid pressure in accelerating the convergence to optimal bone properties, especially in specimens with larger PV porosities. The findings emphasize the importance of fluid pressure in bone remodeling, aligning with previous studies. Furthermore, this study demonstrates that considering transversely isotropic material properties can significantly alter the remodeling configuration compared to isotropic material properties. This highlights the importance of accurately representing the anisotropic nature of cortical bone in models to better predict its adaptive responses. However, aspects such as fluid density variations and bone geometry changes remain unexplored, suggesting directions for future research. Overall, this research enhances the understanding of cortical bone adaptation and its mechanical interactions.

Analytical Formulation and Optimization of the Initial Morphology of Double-Layer Cable Truss Flexible Photovoltaic Supports

With the rapid development of the photovoltaic industry, flexible photovoltaic supports are increasingly widely used. Parameters such as the deflection, span, and cross-sectional dimensions of cables are important factors affecting their mechanical and economic performance. Therefore, in order to reduce steel consumption and cost and improve application value, it is crucial to design and optimize their initial morphology. In this paper, the mechanical behavior of a single-cable structure is introduced, and the simplified analytical formulations for internal force and displacement are deduced based on the geometric nonlinear characteristics and small strain assumption of the flexible photovoltaic supports. On this basis, the analytical expressions for the cable force and displacement of a convex prestressed double-layer cable truss flexible photovoltaic support structure under a uniform load are derived, and the correctness of the analytical formulations is verified by comparing the values with the finite element analysis results. In order to reduce the construction costs of the flexible photovoltaic support, a mathematical model for optimizing the initial structure’s morphology is established according to the analytical formulations. The initial morphology of the double-layer cable truss flexible photovoltaic support is optimized, and the optimization results of different deflection deformation limits and whether the lower load-bearing cable is allowed to relax are compared. The results indicate that the errors of the displacement formulation and cable force formulation, when compared with the finite element results, are less than 3% and 4%, respectively, which verifies the accuracy of the analytical formulations. By analyzing the cable force and displacement of the structure under static action, it is suggested that the deflection limit of the double-layer cable truss structure should be 1/100 of the single span. The lower load-bearing cables of the double-layer cable truss flexible photovoltaic support are highly susceptible to relaxation under wind suction loads, and, by comparing the optimization results, it is suggested that slack should be allowed in the lower load-bearing cables for a better economic effect. When choosing the most economical structure morphology, it is recommended that the total height of the mid-span struts should be 1/20~1/15 of the single span. The analytical formulation and the mathematical model for the optimization of the initial morphology proposed in this paper can provide certain theoretical references and bases for the design of practical engineering projects and play an important role in promoting its application and promotion.

A Theoretical Study on Static Gas Pressure Measurement via Circular Non-Touch Mode Capacitive Pressure Sensor.

A circular non-touch mode capacitive pressure sensor can operate in both transverse and normal uniform loading modes, but the elastic behavior of its movable electrode plate is different under the two different loading modes, making its input-output analytical relationships between pressure and capacitance different. This suggests that when such a sensor operates, respectively, in transverse and normal uniform loading modes, the theory of its numerical design and calibration is different, in other words, the theory for the transverse uniform loading mode (available in the literature) cannot be used as the theory for the normal uniform loading mode (not yet available in the literature). In this paper, a circular non-touch mode capacitive pressure sensor operating in normal uniform loading mode is considered. The elastic behavior of the movable electrode plate of the sensor under normal uniform loading is analytically solved with the improved governing equations, and the improved analytical solution obtained can be used to mathematically describe the movable electrode plate with larger elastic deflections, in comparison with the existing two analytical solutions in the literature. This provides a larger technical space for developing the circular non-touch mode capacitive pressure sensors used for measuring the static gas pressure (belonging to normal uniform loading).

Optimized Electrocatalytic Adsorption Degradation of Oilfield Produced Water Using New Dimension Stable Anode

AbstractIn this study, we synthesized a novel electrode for electrocatalytic adsorption by fabricating ACF‐TiO2 via the sol‐gel method and binding it with IrO2‐TaO2. The electrode's effectiveness in treating oilfield produced water (OPW) was evaluated using batch techniques. Comprehensive characterization, including scanning electron microscopy (SEM), energy‐dispersive spectrometry (EDS), Brunauer‐Emmett‐Teller (BET) analysis, and Fourier‐transform infrared (FTIR) spectroscopy, confirmed uniform TiO2 loading onto the ACF surface, preserving structural integrity. BET analysis indicated increased mesopore volume and enhanced organic adsorption capacity without compromising microporous structure. Additionally, FTIR analysis revealed the emergence of functional groups conducive to adsorption and catalytic reactions. Freundlich isotherms and pseudo‐first‐order kinetics best fit the adsorption data. Remarkably, even after five cycles, the electrode maintained high removal efficiencies for chemical oxygen demand (COD) and oil content at 91.35 % and 91.12 %, respectively. We further investigated the complex phenomena of material adsorption, electrochemical oxidation, and desorption during electrocatalytic adsorption, highlighting the importance of solid‐phase adsorption and liquid‐phase electrocatalytic oxidative decomposition in OPW treatment. Comparison with similar electrodes and DSA electrodes demonstrated the superior performance and practicality of the IrO2‐TaO2‐ACF(TiO2) electrode. Its cost‐effectiveness and regeneration method further enhance its applicability in real‐world scenarios, emphasizing its potential in water treatment.

Nonlinear dynamic study of FG-GFRC-NPR structures

The functionally graded glass fibre-reinforced polymer composite(FG-GFRC) is one of the contemporary sophisticated materials that may be employed for a variety of technical purposes. The shock absorption capacity of FG-GFRP laminates can be improved by incorporating auxetic property (i.e., negative Poisson's ratio NPR) in the structures, which can be attained by a particular stacking sequence of glass fibres (GF) and a different percentage of GF distribution along the thickness direction within the FG-GFRP structure. The nonlinear dynamic behaviour of such structures must be investigated. The clamped-clamped FG-GFRP-NPR structure is stimulated under a uniform transverse load distribution in the current work. Based on the higher-order shear deformation theory (SDT), the displacement field and nonlinear stress–strain relationship are derived. The nonlinear differential equation with cubic non-linear components were derived using Hamilton’s principle and transformed using Galerkin’s technique and obtained governing equation of motion. MATLAB has been used to conduct all numerical simulations. A time series, a phase picture and a Poincare diagram (PCM) were generated to characterize the vibration behavior of such auxetic structures.

Novel and Low-Cost Techniques for Extending the Etch Capabilities of an Inductively Coupled Plasma Etch Tool That Has Clamp Fingers for Clamping 4-Inch Diameter Wafers

Widening the processing capabilities of an inductively coupled plasma (ICP) etch tool by “preventing wafer breakage” during processing of wafers, or by gaining the capability to do “through-wafer silicon etch” are important challenges that may need to be resolved with very limited resources. Resolving the undesired wafer breakage issues caused during processing of wafers is important to reduce the manufacturing costs, and increase production yield. Furthermore, considering the high prices of the state-of-the-art wafer processing tools, it is also important to prevent wafer breakage by using low-cost approaches especially if the resources for purchasing state-of-the-art processing equipment are not available. Two novel methods (method #1, and method #2) are developed to prevent wafer breakage and allow through-wafer silicon etching. With method #1, an aluminium alloy ring (AAR) and an o-ring are employed to obtain uniform load distribution (instead of point loads) on the required outer region on the surface of a wafer, and to minimize or completely remove the bending moment that may be formed on the possible cross-sections of the entire wafer, during clamping of the wafer. With method #2, through-wafer silicon etching is made possible by simultaneous application of method #1 and addition of a helium cooling gas (HCG) leakage blocking dicing tape at the back side of the wafer that is under processing for through-wafer etching. By using the explained methods, wafer breakage during ICP etch processing is eliminated, and through-wafer silicon etching is made possible. From the other side, the effective wafer area that can be used for processing is reduced by 48%. Novel and capability enabling 2 different techniques that are extremely low-cost compared to purchasing a state-of-the-art ICP etch tool are presented to extend the processing capabilities of an ICP etch tool for deep silicon etching (method #1), and through-wafer silicon etching (method #2).

Synthesis and Characterization of Electrospun Ni-BZY Nano-Fiber Anodes

Solid oxide fuel cell (SOFC) and related Protonic Ceramic Fuel Cell (PCFC) technologies have demonstrated significant promise for the efficient and clean electrochemical conversion of stored energy held in a wide variety of renewable fuels, decreasing dependence on traditional fossil fuels. The high efficiencies of both devices arise from the direct chemical-to-electrical energy transformation, achieved without moving parts and the losses inherent to combustion technologies. As in all fuel cells, electrons are generated via oxidation of fuel at the anode to power an external load before returning to the cathode to reduce an oxidant, usually O2. Separating the two electrodes is a dense, gas-tight, electronically insulating electrolyte that permits ion diffusion to complete the circuit. The SOFC’s solid oxide electrolyte passes oxides from the cathode to the anode, but the large activation barrier associated with this process requires high operating temperatures (≥700 ˚C), exacerbating degradative processes and adding challenges for thermal management. In contrast, the PCFC’s perovskite electrolyte permits protonic diffusion from the anode to the cathode, with a smaller activation barrier leading to lower operating temperatures (450 – 700 ˚C). Despite recent advancements in emerging PCFC materials, the overall efficiency and long-term stability of the device is still impacted in part by the anode’s ability to catalyze fuel oxidation, generate protons, and shuttle electrons to an attached current collector. These processes in turn are strongly linked to the morphology and stability of the anode—often a cermet composed of a Ni catalyst/electronic conductor and protonic ceramic such as yttrium-doped barium zirconate (BZY). In particular, continuity is needed for the Ni, BZY, and pore networks while maximizing boundaries between each phase (three-phase boundary). Traditionally, anodes are fabricated by mixing appropriate powders together without much control over the morphology over the micron-sized components. In this study, we explore an alternative approach to systematically engineer Ni-BZY nanofibers within the anode to enhance overall device performance through improving the underlying electrochemical processes at the anode. Low nickel-content BZY anodes (<40 wt. % Ni) for PCFCs are fabricated through electrospinning, with two distinct methods evaluated for nickel loading. First, uniform BZY nanofibers are synthesized by electrospinning a gel containing BZY metal cations and 5 wt. % Polyvinylpyrrolidone (PVP) as dispersant in ethanol/acetic acid solution followed by sintering at 900°C for 3 h in air, and subsequent electroless deposition of nickel on the fiber surfaces. Second, Ni-BZY is prepared by electrospinning a polymer containing a nickel salt and the same BZY precursors followed by co-sintering at 900°C for 3 h. The Ni-BZY fibers underwent morphological, crystallinity and elemental characterization via SEM, XRD, TEM and Raman microscopy. Initial comparison of the fibers fabricated by both methods has shown that uniform nickel loading of ~35 wt. % on the fibers was achieved in the second method. Slurries containing fibers made from both methods are deposited as anodes onto BZY electrolytes, and the complete cells are tested electrochemically under hydrogen at elevated temperature and compared with a control PCFC constructed using conventional powder materials with comparable nickel loading. In summary, electrospun nanofibers, known for their excellent permeability and faster charge transfer due to their porous structure, present an intriguing alternative for high-performance PCFC anode materials. Figure 1

Structural Analysis of Periodic Trusses and Lattice Materials: States of Self-Stress, Mechanisms, and Mechanical Properties

Abstract In the realm of low relative density, a rigid-jointed lattice material exhibits a mechanical response analogous to that of a pin-jointed periodic truss with an identical micro-architecture. This correspondence simplifies the evaluation of the lattice's structural performance. While established matrix methods in linear algebra are capable of determining the states of self-stress, infinitesimal mechanisms, and mechanical properties of pin-jointed periodic trusses, they lack a systematic approach to deriving closed-form expressions for these properties. This paper presents a straightforward approach to address this gap. Furthermore, we introduce an inventive finite element framework that directly yields self-stress states and infinitesimal mechanisms in periodic trusses subjected to specific uniform macroscopic loading conditions. This framework allows for the determination of mechanical properties for periodic trusses by solving straightforward boundary value problems, such as uniaxial tension/compression or simple shear. The developed finite element framework offers greater simplicity compared to the matrix methods, with its benefits becoming more pronounced for complex micro-architectures. To demonstrate the effectiveness of the two newly developed methods, we conduct structural analyses on five different lattice materials, achieving successful outcomes.

Capillary trapping of various nanomaterials on additively manufactured scaffolds for 3D micro-/nanofabrication

High-precision additive manufacturing technologies, such as two-photon polymerization, are mainly limited to photo-curable polymers and currently lacks the possibility to produce multimaterial components. Herein, we report a physically bottom-up assembly strategy that leverages capillary force to trap various nanomaterials and assemble them onto three-dimensional (3D) microscaffolds. This capillary-trapping strategy enables precise and uniform assembly of nanomaterials into versatile 3D microstructures with high uniformity and mass loading. Our approach applies to diverse materials irrespective of their physiochemical properties, including polymers, metals, metal oxides, and others. It can integrate at least four different material types into a single 3D microstructure in a sequential, layer-by-layer manner, opening immense possibilities for tailored functionalities on demand. Furthermore, the 3D microscaffolds are removable, facilitating the creation of pure material-based 3D microstructures. This universal 3D micro-/nanofabrication technique with various nanomaterials enables the creation of advanced miniature devices with potential applications in multifunctional microrobots and smart micromachines.

Particle size effect on the thermoelastic behavior of composites—A comparative study between heterogeneous and homogenized beams

The particle size effect on the overall thermoelastic behavior of a composite containing many identical spherical particles reduces with the specimen-particle size ratio (SPR). When SPR is large enough, the effective stiffness converges, and the homogenized properties can represent the composite. This paper addresses two challenging questions: How large of an SPR is enough to reach the convergent results for different loading conditions, and whether is the critical SPR obtained from a uniform loading condition applicable to a nonuniform loading condition? When a uniform load is applied to a composite beam, the elastic moduli and thermal expansion coefficients can be calculated from the material’s response. When the beam is subjected to pure or thermal bending, the deflection can be predicted by the heterogeneous or homogenized beams. The inclusion-based boundary element method (iBEM) is developed for high-fidelity simulation of many-particle systems. Given a volume fraction of particles, particle and beam size, and beam geometry, the local fields and the effective deformation are calculated for uniform and nonuniform loading conditions. The comparative study between a homogenized beam by the micromechanical approach and the numerical simulation of the heterogeneous particle system shows that a much larger SPR is required for thermal bending to reach a convergent result between the heterogeneous and homogenized beam. When the SPR is moderate, a cross-scale modeling method shall replace the micromechanical modeling to achieve accurate results.

Model Pemilihan Rute Antara Jalan Nasional dan Jalan Tol Surabaya (Bundaran Waru)-Jombang dengan Metode Pembebanan Bertahap

The interactions that occur between the City of Surabaya and the City of Jombang are not only influenced by economic factors, but are also influenced by social factors of life. Residents who are outside the Jombang City area will try to choose the fastest route from several routes that connect their home zone with Jombang City. This research was conducted based on factors that influence the process of choosing a travel route from Surabaya City to Jombang City using class I, class II and class III vehicles. The influencing factors are travel time and vehicle flow. The available route options are via national roads and toll roads. In this research, an analysis of route selection was carried out using the gradual loading method. The gradual loading method was chosen because it can determine the relationship between traffic flow and travel time, without depending on driver assumptions and road network characteristics. After carrying out the analysis using the gradual loading method, the wardrop balance value can then be calculated, the results of which can show that the conditions are balanced and the driver can determine which route to take. From the results of a simple linear regression analysis, a model of the flow - travel cost relationship on the Surabaya - Jombang National Road route was obtained with the equation form 55.63 + 0.031X, while on the Surabaya - Jombang Toll Road route the equation form was 32.044 + 0.024X. The wardrop balance value at a uniform fraction loading of 25% was found to be 0.18 and at a uniform fraction loading of 10% and a non-uniform fraction of 10%, 20%, 30%, 40% the value was 0.03. This value is relatively small and can be interpreted that the condition is close to wardrop equilibrium.

Sodiophilic Substrate Induces NaF-Rich Solid Electrolyte Interface for Dendrite-Free Sodium Metal Anode.

3D substrate with abundant sodiophilic active sites holds promise for implementing dendrite-free sodium metal anodes and high-performance sodium batteries. However, the heightened electrode/electrolyte side reactions stemming from high specific surface area still hinder electrode structure stability and cycling reversibility, particularly under high current densities. Herein, the solid electrolyte interface (SEI) component is regulated and detrimental side reactions are restrained through the uniform loading of Na-Sn alloy onto a porous 3D nanofiber framework (NaSn-PCNF). The strong interaction between Na-Sn alloy and PF6 - anions facilitates the dissociation of sodium salts and releases more free sodium ions for effective charge transfer. Simultaneously, the modulations of the interfacial electrolyte solvation structure and the construction of a high NaF content SEI layer stabilize the electrode/electrolyte interface. NaSn-PCNF symmetrical battery demonstrates stable cycling for over 600 h with an ultralow overpotential of 24.5mV under harsh condition of 10 mA cm-2 and 10 mAh cm-2. Moreover, the full cells and pouch cells exhibit accelerated reaction kinetics and splendid capacity retention, providing valuable insights into the development of advanced Na substrates for high-energy sodium metal batteries.

Distribution and propagation of stress and strain in cube honeycombs as trabecular bone substitutes: Finite element model analysis

For designing trabecular (Tb) bone substitutes suffering from osteoporosis, finite element model (FEM) simulations were conducted on honeycombs (HCs) of 8 × 8 × 1 (2D) and 8 × 8 × 8 (3D) assemblies of cube cellular units consisting of 0.9 mm long Nylon® 66 (PA, Young's modulus E: 2.83 GPa) and polyethylene (PE, E: 1.1 GPa) right square prisms. Osteoporotic damage to the Tb bone was simulated by removing the inner vertical struts (pillars; the number of removed pillars: Δn ≤ 300) and by thinning the strut (thickness, d: 0.4–0.1 mm), while the six facade lattices were kept flawless. Uniform and uniaxial compressive loads on the HCs induced elastic deformation of the struts. The pillars held almost all the load, while the horizontal struts (beams) shared little. E for PA 3D HCs of all d smoothly decreased with Δn. PA 3D HCs of 0.2 mm struts deserved to be the substitutes for Tb bone, while PE 3D HCs of 0.05 mm struts were only for the Tb bone of the poorest bone quality. For the PA 3D HCs, the maximum von Mises stress (σM) first rapidly increased with Δn and showed a break at Δñ50, then gradually approached the yield stress of PA (50 MPa). Moreover, small portions of the stress were transferred from the façade pillars to the adjacent inner beams, especially those near the lost-pillar sites, denoted as X defects. The floor beams of thinner struts associated with the X-defects were lifted, and similar lifting effects in smaller amounts were propagated to the other floors. The 3DHCs of the thicker struts showed no such flexural deformations. The concept of force percolation through the remaining struts was proposed to interpret those mechanical behaviors of the HCs.

Study on fracture of hyperelastic Kirchhoff-Love plates and shells by phase field method

Thin walled structures such as plates and shells are widely used in many engineering fields. To Predict its fracture behavior is of great significance for integrity design and strength evaluation of engineering structures. Numerical simulation of the fracture behavior of hyperelastic plates and shells is a challenge due to complex kinematic description, hyperelastic constitutive relationship, geometric nonlinearity and the degradation on elastic parameter caused by fracture damage. Combining Kirchhoff Love (K-L) shell theory with the fracture phase field method, and numerically discretizing the first and second order partial derivatives of displacement field and phase field by using T-splines and meeting the requirements of K-L plate and shell theory for the C1 continuity of the shape function, a model for the isogeometric analysis numerical formulation of the phase field fracture in hyperelastic K-L plates and shells is established. The fracture failure behavior of hyperelastic K-L plates and shells under the uniform load and displacement load is simulated, and the effect of the Gaussian curvature on the fracture behavior of hyperelastic K-L shells is studied. The simulation results show that the present numerical scheme can effectively capture the complex crack propagation path of plates and shells under the uniform load, and the displacement field can effectively reflect the crack distribution of materials. The thin shell with negative Gaussian curvature shows the excellent fracture performance under the internal pressure, and can withstand the greater internal pressure.

Thermally Induced Nonlinear Bending and Stability of Nanocomposite Curved Pipes Reinforced by CNTs

This research is concerned with the thermal bending and stability of temperature-dependent nanocomposite curved pipes strengthened with carbon nanotubes (CNTs) subjected to uniform temperature rise. Thermo-mechanical characteristics of the polymer composite pipe are assumed to vary entirely in the thickness by a non-uniform function of the radius. Five different patterns are selected to model the propagation profile of CNTs amongst the pipe thickness. Based on the shear deformation and von-Karman kinematic hypothesis, nonlinear balance equations of the polymer curved pipe are determined via varying the total potential energy of the system. Governing equations as a set of coupled nonlinear differential equations are analytically solved using a perturbation-based technique. Closed-form solutions are derived to estimate large-amplitude deflection of nanocomposite curved pipes with pinned and clamped boundaries under uniform thermal loading. The obtained results show the influences of important parameters such as material/geometrical characteristics and foundation stiffness on the thermally induced nonlinear response of polymer nanocomposite curved pipes.

Enhanced catalytic performance for gas phase epoxidation of propylene with H2 and O2 by multiple pretreated Au/TS-1 catalysts

Direct epoxidation of propylene (C3H6) with hydrogen (H2) and oxygen (O2) over Au/TS-1 catalyst was promising way for the synthesis of propylene oxide (PO). However, high selectivity of PO (>95 %) and conversion of C3H6 (>5 %) cannot be achieved at the same time. The industrialization process was severely restricted. In this paper, Au/TS-1 catalysts were synthesized by deposition precipitation method with alkali metal promoter. And alkaline gases and silane coupling post-treatment were performed to promote the catalytic activity. The prepared samples exhibited a much better C3H6 conversion (6.5 %) and PO selectivity (95.1 %) compared with general catalyst using normal synthetic technology. Cs2CO3 was beneficial to increasing Au nanoparticles uptake efficiency. Both NH3 and triethoxyvinylsilane post-treatment were good for smaller and more uniform loading of Au nanoparticles. The decreasing in surface hydroxyl density effectively alleviated the occurrence of PO ring opening isomerization. The increased hydrophobicity of TS-1 surface was conducive to the rapid desorption of generated PO and significantly increased PO selectivity. Multiple pretreatment was also favorable for extending the lifetime of Au/TS-1 catalyst.

Optimization of Fuel Consumption by Controlling the Load Distribution between Engines in an LNG Ship Electric Propulsion Plant

Due to growing environmental concerns and stringent emissions regulations, optimizing the fuel consumption of marine propulsion systems is crucial. This work deals with the potential in an LNG ship propulsion system to reduce fuel consumption through controlled load distribution between engines in Dual-Fuel Diesel Electric (DFDE) plant. Based on cyclical data acquisition measured onboard and using an optimization model, this study evaluates different load distribution strategies between setups according to the optimization model results and automatic (equal) operation to determine their effectiveness in improving fuel efficiency. The analysis includes scenarios with different fuel types, including LNG, MDO and HFO, at different engine loads. The results indicate that load distribution adjustment based on the optimization model results significantly improves fuel efficiency compared to conventional methods of uniform load distribution controlled by power management systems in almost all load intervals. This research contributes to the maritime industry by demonstrating that strategic load management can achieve significant fuel savings and reduce environmental impact, which is in line with global sustainability goals. This work not only provides a framework for the implementation of more efficient energy management systems on LNG vessels, but also sets a benchmark for future innovations in maritime energy optimization as well as in the view of exhaust emission reduction.

Multi-objective optimization and accelerated experimental research on load distribution of planetary roller screw mechanism

Load distribution is a critical characteristic that determines the load carrying capacity of planetary roller screw mechanism (PRSM). First, a load distribution calculation model is established. Subsequently, a multi-objective optimization model to achieve uniform load distribution is constructed based on NSGA-II. Then, considering the optimization effect, machining feasibility and machining efficiency, the optimal load uniform distribution design method for linear thinning of thread thickness is determined using the analytical hierarchy process. Finally, an accelerated test method of PRSM load-bearing characteristics based on abrasive technology is proposed for the first time. The experimental results show that after optimization, the maximum contact width decreases by 12.5% and the fluctuation amplitude decreases by 74.6%, which significantly improves the uniformity of PRSM load distribution.

Tribological behavior of graphene/h-BN vdW heterostructures: the role of defects at the BN layer

Molecular dynamics simulations and first principles calculations were performed to study the tribological behavior of graphene/h-BN (G/h-BN) heterostructures with vacancy and Stone–Wales (SW) defect under uniform normal load, revealing the mechanism of the effect of defect types on friction, and discussing the coupling effect of temperature and interfacial defects on the tribological behavior of G/h-BN heterostructures. Under the normal force of 0.2 nN/atom, the friction force of the four systems is 0.0057, 0.0096, 0.0077, and 0.26 nN, respectively. The friction force of SW defect heterostructure is 45 times that of perfect interface heterostructure. The influence of defect type on friction force is SW > SV > DV. By observing the dynamic change of the Z-direction coordinate position of the sliding layer atoms, the slip potential energy curves and the evolution law of the moiré pattern, the relationship between the structural morphology and the energy change of different defective heterostructures and the frictional behavior was investigated comprehensively and intuitively for the first time. From the perspective of atomic strain, the deformation of heterostructures at the atomic level was quantified. The results showed that at 300 K and 0 K, the maximum strain of atoms in the sliding layer was 11.25% and 9.85%, respectively. The thermal perturbation mainly occurs in the out-of-plane direction, which in turn affects the friction. Through density functional theory, it is found that under uniform load, it is difficult to form bonds between the graphene sliding layer and the substrate layer when the defects are in the h-BN substrate layer, which has less influence on the friction of the system, thus making the defective heterostructures also remainsuperlubricity state. These results provide a new understanding of the interfacial friction of G/h-BN defective heterostructure.

Finite element analysis of characterization parameters the double cracks in linear elastic DCFEM

In fracture mechanics, the lifespan of structures plays an important and effective role in terms of rigidity and resistance to secondary effects linked to direct friction and the effects of the atmosphere, in order to avoid any danger that could end to the life of the work. structure, and among these effects are those linked to internal and external cracks. Sometimes the structure may be exposed to double cracks resulting from external loads and influences, such as our study that we present in this paper. We must also not forget the structures which contain holes, which play an important role in tension with other elements and have an essential function in operation and resistance. We don't forget the basic dimensions between the crack and the other. These days, numerical modeling techniques, such the finite element method which is the most popular approach for determining characterisation parameters at the bottom of a crack are the foundation for fatigue problem analysis. This work aims to investigate the impact of two-dimensional parameters (b, c) and the crack length (a) on crack parameters, including the J-integral and stress intensity factor (SIF), of an aluminum alloy structure with a double starting fracture. The finite element method (DCFEM) has been used to study these characteristics under uniform tensile loading. After that, rupture happens in plane stress under mode I loading, and the modeling is done using 4-node CPS4R quadratic elements. Numerous instances have been provided. The optimal rupture resistance solution for plates with two cracks on each sides will be developed using the results obtained.