Displacement Behavior Research Articles

Weight reduction in material extrusion composite parts: pin-bearing behavior analysis

Abstract This study investigated the performance of lightweight samples in pin-bearing tests. The samples were manufactured through Material Extrusion technology of nylon reinforced with short carbon fibers. Their design was based on infill strategy, density, and raster angle. Load–displacement curves and failure mechanisms were analyzed across configurations, with statistical methods applied to evaluate the influence of design factors on maximum stress, relative displacement, and stiffness. Results reveal distinct load–displacement behaviors and failure mechanisms, with deposition strategies tailored to specific final purposes. Specifically, the study identifies gyroid infill, 50% density, and a raster angle of 45° as the optimal solution for maximizing bearing stress. This configuration exhibits a weight and printing time reduction of 40% and 8% concerning the full sample, and a performance reduction in the range of 30–56%, considering both stress (28.2 MPa vs 65.8 MPa) and displacement reduction (9.4 mm vs 15.1 mm). Conversely, rectangular infill, 50% density and raster angle of 0° emerge as the optimal solution for minimizing displacement and maximizing stiffness. This configuration exhibits a weight and printing time reduction of 39% and 34%, in comparison to the full sample, and a performance reduction of about 65–70% (displacement of 4.6 mm at a maximum stress of 23.7 MPa). The triangular strategy can be used to reach elevated values for all output parameters (up to 25.9 MPa as maximum stress, 9.4 mm as maximum displacement, and 242.4 MPa for stiffness), with weight and printing time saving in the range of 41–54% and 34–36% respectively.

Quantum Dynamics Simulations of Exciton Polariton Transport.

Recent experiments have shown that exciton transport can be significantly enhanced through hybridization with confined photonic modes in a cavity. The light-matter hybridization generates exciton-polariton (EP) bands, whose group velocity is significantly larger than the excitons. Dissipative mechanisms that affect the constituent states of EPs, such as exciton-phonon coupling and cavity loss, have been observed to reduce the group velocities in experiments. To elucidate the impacts of these dissipative mechanisms on polariton transport, we developed an efficient quantum dynamics approach that allows us to directly simulate polariton transport under the collective coupling regime and beyond long-wavelength approximation. Our numerical results suggest a renormalization of the group velocities with stronger exciton-phonon coupling strengths and a smaller Q-factor. We observe the transition from ballistic to diffusive propagation as well as the quality-factor-dependent behavior of the transient mean square displacement, agreeing well with the recent experimental measurements.

Mechanical response of elevated bridge piles to adjacent deep excavation

In urban concentrated area, the disturbance caused by construction affects significantly the sustainability of adjacent existing structures. It is essential to capture the mechanical response of existing structures to adjacent deep excavation. The objective of this paper is to investigate the displacement and internal force behavior of elevated bridge piles (BP) subject to influence of deep excavation. A three-dimensional finite element model is established by taking the project of a deep excavation near elevated bridge as an example. The numerically calculated results agree well with the measured data, which verifies the established numerical model. On the basis of this model, the influence of deep excavation on the mechanical characteristics of adjacent piles is captured. The results show that the displacement, bending moment, and shear force of piles are sensitive to the excavation depth. Their magnitudes increase with the increase of excavation depth. When the excavation is completed, the maximum displacements of piles in horizontal direction and vertical direction are 2.3 mm and 10.05 mm, respectively. The maximum bending moment is 1,140.8 kN·m. The maximum and minimum shear forces are 1,206 kN and -2,282 kN, respectively. The piles are mainly under pressure. The maximum pressure is -13,116 kN. The axial force is not sensitive to the depth of excavation. The deformation and internal force of piles exhibit obvious spatial distribution characteristics, and the closer the distance to the middle of the long side of the deep excavation, the greater the value. The research results have a positive effect on the optimization of related engineering structures and the promotion of sustainable development in urban concentrated area.

Molecular Dynamics Simulation on the Mechanism of Shale Oil Displacement by Carbon Dioxide in Inorganic Nanopores

Shale oil reservoirs feature a considerable number of nanopores and complex minerals, and the impact of nano-pore confinement and pore types frequently poses challenges to the efficient development of shale oil. For shale oil reservoirs, CO2 flooding can effectively lower crude oil viscosity, enhance reservoir physical properties, and thereby increase recovery. In this paper, the CO2 displacement process in the nanoscale pores of shale oil was simulated through the molecular dynamic simulation method. The performance disparity of quartz and calcite slit nanopores was discussed, and the influences of nanoscale pore types and displacement rates on CO2 displacement behavior were further analyzed. The results demonstrate that the CO2 displacement processes of different inorganic pores vary. In contrast, the displacement efficiency of light oil components is higher and the transportation distance is longer. Intermolecular interaction has a remarkable effect on the displacement behavior of CO2 in nanopores. On the other hand, it is discovered that a lower displacement rate is conducive to the miscible process of alkane and CO2 and the overall displacement process of CO2. The displacement efficiency drops significantly with the increase in displacement velocity. Nevertheless, once the displacement speed is extremely high, a strong driving force can facilitate the forward movement of alkane, and the displacement efficiency will recover slightly.

Dynamics of nanoparticle tracers in supercooled nanoparticle matrices.

We investigate the dynamics of tracer nanoparticles in bulk supercooled nanoparticle matrices using confocal microscopy. We mix fluorescent (tracer) and undyed (matrix) charged-stabilized polystyrene nanoparticles with tracer-to-matrix particle size ratios δ = 0.34, 0.36, 0.45, 0.71 at various matrix volume fractions ϕ. Single-particle and collective dynamics were obtained from particle-tracking algorithms and differential dynamic microscopy (DDM), respectively. The long-time behavior of the tracer mean-square displacement (MSD) and the shape of the distributions of particle displacements depend on δ and ϕ. At sufficiently large ϕ, small tracers (δ ≤ 0.36) remain mobile and subdiffusive but large tracers (δ ≥ 0.45) are dynamically arrested. The relaxation times determined from the intermediate scattering function (ISF) increase with δ and ϕ. Anomalous logarithmic decays in the ISF are observed for tracers of size δ ≤ 0.36 over a length scale of four to ten matrix particle diameters. These results provide insight into how penetrant size affects the transport of nanoparticles in porous media with soft interparticle interactions.

Mechanism of CO2 flooding in shale reservoirs - insights from nanofluids.

The development potential of CO2-enhanced shale oil recovery is significant, but shale reservoirs have developed nanoscale pores, often accompanied by fissures and micro/nanoscale fractures. This characteristic makes the micro-nanoscale CO2 flooding mechanism unclear. In this study, the minimum miscible pressure (MMP) of CO2 and n-octane was determined from a microscopic perspective using the nanofluidic method. Based on this, the displacement behavior of CO2 in three types of micro-nano networks was investigated, and the degree of inter-fracture matrix utilization was studied for the first time using visualization techniques. It was found that compared to immiscible flooding, the stronger the heterogeneity, the more pronounced the improvement in recovery efficiency by miscible flooding. In addition, transfer and diffusion in the nanofracture network system are intense, and the displacement process can be divided into three stages: pressure-driven flow, matrix-fracture co-production, and matrix oil production. This study applies a novel nanofluidic method to extend the lower limit of the microscopic visualization experimental pore scale to 30 nm, filling the gap in experimental research on shale microscale flow and contributing to the understanding of the mechanism of CO2-enhanced recovery in shale reservoirs. Additionally, it provides necessary references for microscopic flow simulation.

A critical multi-parameter analysis of the densification process on the dimensional stability and bending performance of densified timber

Timber densification is a process wherein various parameters can affect the physical and mechanical properties of the final product. Therefore, it is vital to understand the effects of these parameters to fully exploit the benefits of densification such as improved density, stiffness, and strength. The purpose of this study is to improve on the mechanical properties of Radiata pine (Pinus radiata) and to determine the influence of the process parameters. The densification process and the bending properties of the densified timber were investigated using a fractional factorial experimental design to determine the influence of various parameters (compression ratio, moisture content, compression temperature, heating time, setting temperature, and setting time) on the final product. Among the six process parameters, the compression ratio was the most significant factor with respect to bending properties of the densified timber, while the effect of the other parameters does not show a specific trend with respect to the load–displacement behaviour of the test specimens. A predictive model has been proposed herein to determine the properties of densified timber based on a reduced number of process parameters, with examples based on different design applications.

Experimental Investigation of the Impact of Mixed Wettability on Pore-Scale Fluid Displacement: A Microfluidic Study.

Understanding rock wettability is crucial across various fields including hydrology, subsurface fluid storage and extraction, and environmental sciences. In natural subsurface formations like carbonate and shale, mixed wettability is frequently observed, characterized by heterogeneous regions at the pore scale that exhibit both hydrophilic (water-wet) and hydrophobic (oil-wet) characteristics. Despite its common occurrence, the impact of mixed wettability on immiscible fluid displacement at the pore scale remains poorly understood, creating a gap in effective modeling and prediction of fluid behavior in porous media. The primary objective of this study was to investigate how mixed wettability affects pore-scale fluid displacement dynamics, utilizing microfluidic devices designed to replicate rock-like structures with varied wettability properties. Current techniques for achieving mixed wettability within microfluidic devices often struggle with spatial control and resolution, limiting their accuracy. To address this limitation, a novel approach was employed that combined photolithography and molecular vapor deposition of perfluorodecyltrichlorosilane to precisely and selectively modify wettability within specific pore regions, achieving a mixed wettability distribution correlated with pore size for the first time. The experimental setup included five identical micromodels representing distinct wetting conditions, which were initially saturated with air and subsequently flooded by water. By systematically varying the ratio of hydrophilic to hydrophobic areas, we covered a range from fully hydrophilic to fully hydrophobic and intermediate mixed wettability configurations. Comparative displacement experiments revealed that pore-level mixed wettability has a pronounced effect on fluid displacement behavior, influencing the injection time, spatial invasion patterns, and dynamic pressure profiles. Results indicated that both the injection time and dynamic pressure decreased with an increase in the hydrophilic area fraction. Each wettability configuration displayed unique sequences of pore-filling events, emphasizing the critical role of the wettability distribution in influencing displacement dynamics. While mixed wettability exhibited a clear monotonic effect on invasion time and dynamic pressure, saturation behavior was notably nonmonotonic. Interestingly, mixed wettability scenarios with relatively medium to high hydrophilic fractions demonstrated enhanced overall sweep efficiency compared to the hydrophobic case and reduced the bypassed gas phase relative to the hydrophilic case. However, inefficiently distributed mixed wet zones were found to reduce the sweep efficiency. These findings highlight the critical influence of mixed wettability in fluid displacement processes, with significant implications for applications in oil recovery, CO2 sequestration, and other subsurface energy technologies.

Manufacturing design and static analysis of a gear shaft

This paper presents a gear shaft design that was constructed with the use of Solidworks, the manufacturing process of the design done by the use of the Edgecam software and also a Finite Element Analysis (FEA) which includes examining the part's displacement behavior with corresponding stress and deformation. The 3-dimensional finite element simulation and meshing of the model was done with the ANSYS Workbench. Boundary requirements including external loads were also utilized. The manufacturing design was done in two parts due to the high level of complexity associated with the gear shaft. The first part included the parametric configurations used for machining one end of the gear shaft and the second part included the parametric configurations used for machining the other end of the gear shaft. This means that when the machining process has to be done on the CNC machine, there will be two separate CNC codes to be utilized which can run successively. During the manufacturing design phase, important information was obtained, such as the overall time for machining of one or both ends of the gear shaft as well as the safety conditions that were utilized during the process.

Microfluidic investigation on microscopic flow and displacement behavior of CO2 multiphase system for CCUS-EOR in heterogeneous porous media

Microfluidic investigation on microscopic flow and displacement behavior of CO2 multiphase system for CCUS-EOR in heterogeneous porous media

Advanced Numerical Simulation of Pendulum Dynamics: A Comprehensive Analysis of Environmental Influences and Non-Linear Behavior

This study explores the intricate dynamics of pendulum motion by numerically simulating the influence of environmental factors, including temperature, pressure, and humidity. Employing a high-precision Euler method with a time step of 0.0001 seconds, a 1-meter-long pendulum was modeled under varying conditions: temperatures ranging from 0°C to 40°C, pressures between 950 hPa and 1050 hPa, and humidity levels from 20% to 80%. The simulation incorporated key factors such as thermal expansion, air resistance, and non-linear oscillatory behavior for initial displacements up to 30°. Results reveal that a 40°C rise in temperature induces a 0.0007-second change in period and a 0.001 m/s² variation in calculated gravitational acceleration, predominantly due to rod expansion. Conversely, the effects of pressure and humidity were found to be negligible. Non-linear analysis at a 30° initial displacement indicated a 0.5% increase in period compared to 5°, underscoring the impact of the initial angle on pendulum dynamics. The model demonstrated remarkable accuracy for small-angle oscillations, aligning within 0.01% of theoretical predictions and 0.1% of experimental data. These findings offer valuable insights into pendulum behavior under diverse environmental conditions, providing a robust foundation for advancing the design and calibration of precision instruments and timekeeping mechanisms.

Active Displacement of a Unique Diatom–Ciliate Symbiotic Association

Adaptive movement in response to individual interactions represents a fundamental evolutionary solution found by both unicellular organisms and metazoans to avoid predators, search for resources or conspecifics for mating, and engage in other collaborative endeavors. Displacement processes are known to affect interspecific relationships, especially when linked to foraging strategies. Various displacement phenomena occur in marine plankton, ranging from the large-scale diel vertical migration of zooplankton to microscale interactions around microalgal cells. Among these symbiotic interactions, collaboration between the centric diatom Chaetoceros coarctatus and the peritrich ciliate Vorticella oceanica is widely known and has been recorded in several studies. Here, using 2D and 3D tracking records, we describe the movement patterns of the non-motile, chain-forming diatoms (C. coarctatus) carried by epibiotic ciliates (V. oceanica). The reported data on the Chaetoceros–Vorticella association illustrated the consortium’s ability to generate distinct motility patterns. We established that the currents generated by the attached ciliates, along with the variability in the contraction and relaxation of ciliate stalks in response to food concentration, resulted in three types of trajectories for the consortium. The characteristics of these distinct paths were determined using robust statistical methods, indicating that the different displacement behaviors allowed the consortium to adequately explore distributed resources and remain within the food-rich layers provided in the experimental containers. A simple mechanical–stochastic model was successfully applied to simulate the observed displacement patterns, further supporting the proposed mechanisms of collective response to the environment.

Research on mechanical behavior of corroded RC beams under impact load and peak impact load prediction model

Recent research has extensively investigated the impact behavior of reinforced concrete beams (RC), with growing attention to the degradation caused by corrosion. Despite these efforts, the complex interplay between corrosion rate and impact loading parameters remains insufficiently understood. To address these knowledge gaps, this study examines the effects of corrosion rate and drop hammer height on the dynamic performance of RC beams, which is essential for understanding structural resilience under extreme conditions. Experiments were conducted with corrosion rates of 0 %, 5 %, 10 %, 15 %, and 20 %, and drop hammer heights of 1 m, 2 m, and 3 m. The study provides novel insights into the failure characteristics, dynamic responses, energy dissipation, and load–displacement behavior of corroded RC beams. The results indicated that higher corrosion rates increased both the number and width of cracks. At the same drop hammer height, the peak impact load decreases as the stirrup corrosion level increases. The energy dissipation shows a positive correlation with drop hammer height, with impulse increasing as the height rises. A predictive model for peak impact load was developed, showcasing a strong correlation between experimental and simulation results, offering a new theoretical framework for assessing structural safety under varying degrees of corrosion.

Hydrogen, Methane, Brine Flow Behavior, and Saturation in Sandstone Cores During H2 and CH4 Injection and Displacement

Large-scale underground hydrogen storage (UHS) is a critical component in the emerging hydrogen economy. Knowledge of multiphase flow behavior involving hydrogen in storage reservoir formations is crucial to characterizing hydrogen transport properties and essential for the deliverability and storage operations of UHS. There are still many gaps in fully understanding hydrogen–methane–brine multiphase phase flow that require further investigation. In this work, H2 and CH4 were injected through brine-saturated sandstone cores using a tri-axial core holder system fitted with flow rate meters and pressure transducers, while the effluent gas concentrations were analyzed using an online micro gas chromatograph. Brine displacement, permeability, and gas breakthrough curves were measured. We studied the flow behavior of hydrogen and methane in sandstone cores through testing brine displacement by gas injection and comparing the hydrogen displacement of methane with the methane displacement of hydrogen. We also tested the differences between horizontal and vertical flow in brine displacement. The results showed that brine displacement was more efficient in a core with higher permeability and porosity, resulting in a higher initial gas saturation. A higher gas injection rate brought about faster gas breakthrough measured by pore volume and sharper concentration curves. Hydrogen did not exhibit abnormal flow in the sandstone when the flow was horizontal and downward vertical. Gas overriding was observed in brine displacements when the flow was horizontal, with hydrogen showing this behavior more profoundly compared to methane. Downward vertical gas injection induced higher efficiency brine displacement compared to horizontal displacement and resulted in a higher initial gas saturation in the sandstone cores. These findings address critical knowledge gaps regarding gas flow patterns and displacement behaviors during hydrogen injection and recovery phases in UHS facilities using methane as the cushion gas. The insights from this research offer valuable guidance for optimizing UHS systems, ensuring operational efficiency, and advancing sustainable energy solutions in alignment with decarbonization goals.

Experiment and prediction of enhanced gas storage capacity in depleted gas reservoirs for clean energy applications

Utilizing depleted gas reservoirs for gas storage is the most efficient method. However, the impact of multi-cycle injection-production and water invasion on rock properties and gas-water seepage dynamics remains unclear. This study investigates such reservoirs' multi-cycle stress sensitivity and gas-water displacement behavior. Results show that multi-cycle injection-production and water invasion increase the stress sensitivity of the gas and damage gas storage space and seepage channels. This study also proposed a new unsteady gas-water relative permeability testing method and a prediction model based on in-situ X-ray CT scanning, improving measurement accuracy by 30 %. The results found that the gas's relative permeability is directly proportional to the injection rate and inversely proportional to the initial gas saturation. A gas-water relative permeability model was established, demonstrating that gas-water interference intensifies as the number of cycles increases. In a gas-water transition zone in depleted gas reservoirs, gas relative permeability damage reaches 81 %, reducing the movable pore space and impacting injection-production rates and capacity. This study offers valuable recommendations for optimizing production and dynamic prediction in depleted gas reservoirs, contributing to clean energy applications.

Gender Dimensions of Forced Displacement: A Brief Review and Introduction to the Special Issue

Displacement has increased continuously over the last 12 years and the number of forcibly displaced persons has reached an unprecedented level. More than half of all forcibly displaced persons are girls or women; yet very little is known about how gender intersects the behavior and welfare of forced displacement. This special issue focuses specifically on the gender dimensions of forced displacement. We make both topical and methodological contributions to knowledge about gender norms, livelihoods, multi-dimensional and income poverty, and gender-based violence and discuss the implications of our findings for future research, policy and practice.

Analysis of bolt bonding surfaces by the finite element method based on the equivalent Iwan model

This study establishes a finite element model based on the Iwan model to accurately characterize the force–displacement relationship and energy dissipation in bolted joints under small-amplitude tangential displacement. The force–displacement behavior of the Iwan model is transformed into a stress–strain relationship using a hybrid hardened intrinsic model. A subroutine developed with UMAT and UHARD is used to simulate the elastic–plastic behavior of the Iwan model during surface contact in the finite element model. Three-dimensional modeling and joint simulation are conducted using ABAQUS software. Experimental data verify the model's validity, and the effects of multiple factors on the bolted bonding surface are analyzed. The influence of friction coefficient, cyclic displacement amplitude, and preload on the force–displacement relationship of the bolted bonding surface is explored. Polynomial interpolation of the loading and unloading curves is applied to investigate the energy dissipation phenomenon. Results show that the finite element method can effectively reflect the hysteresis and energy dissipation behavior of the bonding surface. Increased friction coefficient and preload improve residual stiffness and energy dissipation capacity, while larger cyclic displacement amplitudes increase energy dissipation but have a minimal effect on residual stiffness.

Comparison of the Biomechanical Effect of Distal İmplants Placed at Different Angles in the All-On-Four Technique: A Nonlinear Finite Element Analysis: (Effect of Distal Implant Angles in All-on-Four)

IntroductionThe "All-on-four" technique addresses this by placing two vertical implants in the anterior region and two posterior implants angled up to 45 degrees. This study evaluates stress distribution on bone, implants, abutments, gingiva, and prostheses based on posterior implant angulation, using both standard and angled neck implants. Additionally, angled neck implants were used alongside standard implants. MethodsTo evaluate the biomechanical stress and displacement behavior of implants placed at 15°, 30°, 45°, and 30° neck-angled in the interforaminal region of using the All-on-four technique, under a 200N masticatory force on bone, implant, abutment, and prosthesis, using the FEA method with a nonlinear solver. ResultsThe stress values measured in the neck region of the angled implant and abutment placed in the distal region were highest in model IV (305 and 420 MPa), followed model III (282 and 359 MPa), model II (192 and 337 MPa) and lowest in model I (177 and 225 MPa), respectively. The mean elemental von Mises stress in the mandibular bone region where the implant was placed was highest in model I (56 MPa) and lowest in model III (40.4 MPa). ConclusionAs the angle of insertion of the implant into the bone increases, the biomechanical stress value on the implant and abutment also increases. Among the models, the lowest von Mises stress values on the implant and abutment were measured in model I and model II. Models with low stress values can be recommended for patients with clinical conditions and biomechanical risk factors.

Experimental Study on the Influence of Sidewall Excavation Width and Rock Wall Slope on the Stability of the Surrounding Rock in Hanging Tunnels

Hanging tunnels are a unique type of highway constructed on hard cliffs and towering mountains, renowned for their steep and distinctive characteristics. Compared to traditional full tunnels or open excavations, hanging tunnels offer significant advantages in terms of cost and construction time. However, the engineering design and construction cases of such tunnels are rarely reported, and concerns about construction safety and surrounding rock stability have become focal points. Taking the Shibanhe hanging tunnel as a case study, this paper focuses on the stability of the surrounding rock during the excavation of limestone hanging tunnels using physical analog model (PAM) experiments and numerical calculation. Firstly, based on the similarity principle and orthogonal experiments, river sand, bentonite, gypsum and P.O42.5 ordinary Portland cement were selected as the raw materials to configure similar materials from limestone. Secondly, according to the characteristics of hanging tunnels, geological models were designed, and excavation experiments with three different sidewall excavation widths and rock wall slopes were carried out. The effects of these variables on the stress and displacement behavior of the surrounding rock were analyzed, and the laws of their influence on the stability of the surrounding rock were explored. Finally, numerical simulations were employed to simulate the tunnel excavation, and the results of the numerical simulations and PAM experiments were compared and analyzed to verify the reliability of the PAM experiment. The results showed that the vertical stress on the rock pillars was significantly affected by the sidewall excavation widths, with a maximum increase rate of 53.8%. The displacement of the sidewall opening top was greatly influenced by the sidewall excavation widths, while the displacement of the sidewalls was more influenced by the rock wall slope. The experimental results of the PAM are consistent with the displacement and stress trends observed in the numerical simulation results, verifying their reliability. These findings can provide valuable guidance and reference for the design and construction of hanging tunnels.

Numerical study of delamination process of the CFRP composite

A quasi-static approach for an interface damage model, incorporating Rayleigh damping for viscoelastic carbon fiber reinforced polymer composites, is introduced. The interface traction-relative displacement behavior is modeled using a thin adhesive layer, similar to cohesive zone models. The problem is solved numerically with a semi-implicit time-stepping method. The cohesive interface model, integrated into the Finite Element Method, was applied to determine the critical force away from the crack tip. Results showed that the numerical delamination under mode I conditions aligned well with experimental data for the cohesive zone formulations studied. The numerical example demonstrates the effectiveness of the proposed model.