Impact Of Eccentricity Research Articles

An In-Depth Review on the Eccentric Compression Performance of Engineered Bamboo Columns

This review paper delves into the eccentric compression performance of engineered bamboo columns, focusing on objectives like evaluating methodologies, influential parameters, and testing techniques for eccentric compression behavior. It employs a systematic literature review adhering to PRISMA 2020 guidelines to synthesize data from various studies on material properties, design parameters, and construction methods. The findings reveal challenges in predicting failure modes under eccentric compression and the need for a unified model to assess the impact of eccentricity and slenderness ratios on performance. It introduces novel insights into the standardization and testing of engineered bamboo for structural applications. It addresses a significant gap in current research by offering a comprehensive predictive framework for eccentrically loaded, engineered bamboo columns. Doi: 10.28991/CEJ-2024-010-03-020 Full Text: PDF

Three-dimensional numerical investigation of a suspension flow in an eccentric Couette flow geometry

This paper investigates the influence of eccentricity on flow characteristics and particle migration in Couette geometries. The study involves numerical simulations using the recent frame-invariant model developed by Badia et al. [J. Non-Newtonian Fluid Mech. 309, 104904 (2022)]. The study begins with a two-dimensional analysis, focusing first on the Newtonian fluid in order to thoroughly characterize the specific properties of this flow configuration. Next, the impact of eccentricity on particle migration in an isodense suspension is examined by numerical simulations based on the experiments conducted by Subia et al. [J. Fluid Mech. 373, 193–219 (1998)]. Furthermore, the study is extended to include a full three-dimensional analysis of a dense suspension flow in an eccentric Couette geometry based on resuspension experiments conducted by Saint-Michel et al. [Phys. Fluids 31, 103301 (2019)] and D'Ambrosio et al.[J. Fluid Mech. 911, A22 (2021)]. The main objective of the latter study is to investigate the influence of eccentricity on the resuspension height and on the calculation of the particle normal stress in the vertical direction through the volume fraction profile analysis. Our results show that even minimal eccentricity can lead to significant changes compared to the centered case.

Design of sustainable energy harvesters using a 3D car suspension system model and half-width speed bump

This study aims to not only design a vibration energy harvester integrated in a three-dimensional (3D) multi-particle system but also investigate the longitudinal and lateral body sway and the effect of front and back wheel interlocking caused by the eccentric loading of the vehicle. Using multidimensional vehicle suspension system vibration modes for analysis, this study evaluates the impact of lateral and longitudinal eccentricity on the displacement of the four-suspension system wheel axes. In addition, this study discusses the effect of discontinuous half-width sinusoidal speed bump on power generation and maximum power generation capacity under good ride comfort conditions. To maximize the efficient electrical power from the car's suspension system through the use of energy harvesters, we have employed the simulated annealing algorithm, a robust global optimization technique. The objective function chosen for this optimization is the root-mean-square (RMS) electrical power, represented as WTT(RMS). In addition to this, we have considered the comfort experienced by passengers, incorporating the ride comfort efficiency into the objective function during the optimization process. As a result of this optimization, a 3D car model equipped with four energy harvesters has been fine-tuned to achieve a significant increase in induced electrical power, ultimately reaching an impressive 0.2 W.

Impact of Tool Eccentricity on Acoustic Logging Response in Horizontal Wells: Insights from Physical Simulation Experiments

Horizontal wells are extensively utilized in the development of unconventional reservoirs. However, the logging responses and formation evaluation in horizontal wells can be impacted by factors like anisotropy and tool eccentricity. To investigate the influence of tool eccentricity on acoustic logging response, physical simulation experiments of array acoustic logging were conducted in a scaled borehole formation model under different tool eccentricity conditions. The experimental data were analyzed, and the findings revealed that when the receiver array is parallel to the borehole axis, the P-wave slowness and S-wave slowness remain unaffected by tool eccentricity. However, the amplitudes of the P-wave and S-wave decrease significantly with increasing tool eccentricity, following an approximate negative exponential pattern. Additionally, when the transmitter is centered and the receiver array intersects the borehole axis at an angle, the wave velocities increase significantly with tool eccentricity, with the P-wave velocity showing a faster increase. Conversely, when the transmitter is eccentric and the receiver array intersects the borehole axis at an angle, the wave velocity decreases notably with tool eccentricity, and the P-wave velocity decreases even faster. These findings contribute to a better understanding of the impact of tool eccentricity on array acoustic logging response in horizontal wells and offer guidance for developing correction schemes to address this effect.

Dynamic Eccentricity Impact on Electromagnetic Vibration and Acoustic Noise of Interior Permanent Magnet Synchronous Motors With Different Numbers of Parallel Branches

Dynamic Eccentricity Impact on Electromagnetic Vibration and Acoustic Noise of Interior Permanent Magnet Synchronous Motors With Different Numbers of Parallel Branches

Rotor Eccentricity Impact on Electromagnetic Behavior in Combined Winding Bearingless Motors Towards Displacement Self-Sensing

Rotor Eccentricity Impact on Electromagnetic Behavior in Combined Winding Bearingless Motors Towards Displacement Self-Sensing

Numerical Simulation and Experimental Research on Heat Transfer Characteristics Based on Internal Meshing Screw

The mixing and processing of high-viscosity materials play a pivotal role in composite material processing. In this context, the internal meshing screw mixer, rooted in volume extensional rheology, offers distinct advantages, including heightened mixing efficiency, exceptional material adaptability, and favorable thermomechanical properties. This research endeavors to advance our understanding of these qualities by presenting an in-depth exploration of internal meshing screw mixing. To facilitate this, an internal meshing screw mixing experimental apparatus was meticulously constructed, accompanied by extensive numerical simulations and experimental investigations into its heat transfer characteristics. Two distinct heat transfer modes are established: Mode 1 entails the transfer of the high temperature from the outer wall of the stator to the interior, while Mode 2 involves the transmission of the high temperature from the inner wall of the rotor to the exterior. The ensuing research yields several notable findings: 1. It is evident that higher rotational speeds lead to enhanced heat transfer efficiency across the board. However, among the three rotational speeds examined, 60 rpm emerges as the optimal parameter for achieving the highest heat transfer efficiency. Furthermore, within this parameter, the heat transfer efficiency is superior in Mode 1 compared to Mode 2. 2. As eccentricity increases, a corresponding decline in comprehensive heat transfer efficiency is observed. Moreover, the impact of eccentricity on heat transfer efficiency becomes increasingly pronounced over time. 3. A lower gap dimension contributes to higher heat transfer within the system. Nevertheless, this heightened heat transfer comes at the expense of reduced stability in the heat transfer process. 4. It is demonstrated that heat transfer in Mode 1 primarily follows a convection heat transfer mechanism, while Mode 2 predominantly exhibits diffusion-based heat transfer. The heat transfer efficiency of Mode 1 significantly surpasses that of Mode 2. This research substantiates its findings with the potential to enhance the heat transfer efficiency of internal meshing screw mixers, thereby making a valuable contribution to the field of polymer engineering and science.

Seismic Response Effect on Base-Isolated Rigid Structures by Mass Eccentricity in Nuclear Plants

The purpose of this paper is to analyze the seismic response effect caused by the mass eccentricity of individual equipment when conducting base isolation for the improvement of the seismic performance of a nuclear power plant. Recent research has interpreted and confirmed through analysis and testing that base isolation for safety-related equipment in nuclear power plants is an efficient alternative to designing for excessive seismic loads. Depending on the equipment, unavoidable mass eccentricity can occur, which necessitates verification of the response impact caused by eccentricity. In this paper, we analyze the seismic response impact of equipment with mass eccentricity using small base isolators. To do so, sensitivity analysis of the seismic response due to mass eccentricity is conducted for a base-isolated concentrated mass model. Furthermore, three efficient mass eccentricity models suitable for testing are designed and manufactured. Simulation analyses using the finite element method (FEM) models are performed, followed by three-axis shake table tests to validate the seismic response impact of mass eccentricity. In conclusion, it is confirmed that applying small base isolators to equipment with mass eccentricity can affect seismic response impact to some extent when compared for a beyond-design-basis earthquake (BDBE).

Handling inevitable collision states by Advanced Driver Assistance Systems functions: software-in-the-loop performance assessment of an injury risk-based logic in a “lane departure” scenario

The downward trend in the number of fatalities and serious injuries related to road accidents depends on the implementation of increasingly performing Advanced Driver Assistance Systems (ADAS) in the circulating fleet. The greatest benefit of the adoption of ADASs like Autonomous Emergency Braking (AEB) consists in limiting the frequency of impacts. However, in Inevitable Collision States (ICSs), the decrease in impact closing speed guaranteed by the AEB may not reduce the Injury Risk (IR) for the occupants: IR is a function of the vehicle’s velocity change in the collision () – a combination of impact closing speed and impact eccentricity. The work virtually analyses, in lane departure ICS scenarios, the performance of an adaptive steering and braking intervention logic based on instantaneous IR minimization. The adaptive logic reduces IR compared to the absence of intervention (down to 80 times lower) and to the AEB (down to 40 times lower) by leading the ego vehicle toward eccentric impact configurations. It is highlighted that full activation of the steer-by-wire system in 0.3 s allows the adaptive logic to also reduce the frequency of impacts; it is further evidenced that employing a function capable of modulating the braking level to minimize IR entails disadvantages from the IR perspective compared to the AEB: efficient intervention strategies on the steering are the only alternative for increasing the safety provided by high-performance ADASs. Finally, compared to previous literature, the study highlights high efficiencies of the adaptive logic in a wide range of ICS scenarios.

Full-scale testing of precast tunnel lining segments under thrust jack loading: Design limits and ultimate response

In modern practice, precast segmental tunnel linings are typically installed via a tunnel boring machine (TBM), which advances by thrusting against the previously installed segmental ring. The forces applied through the thrust jack pads can induce significant bursting and spalling tensile stresses and strains in the segment, and improperly designed segments can suffer from cracking as a result. An experimental study has been conducted to evaluate the progression of damage from initial cracking to ultimate capacity for full-scale precast tunnel liner segments under thrust jack loading. The baseline segment design is composed of steel fiber reinforced concrete (SFRC), and the impact of supplemental conventional steel bar reinforcement and load application eccentricity were also investigated. Six full-scale tests were performed with a thrust jack load per pad up to 22.2 MN (which is ∼ 3.8 times the maximum expected installation thrust force). At the maximum expected thrust jack load during installation (5.78 MN per pad), the segments were virtually undamaged, and hairline cracking initiated between the load pads on only one test. At the TBM’s ultimate jacking capacity (9.55 MN per pad) surface cracking was observed between and under the load pads; however, the crack width remained below 0.2 mm for all specimens. The formation of cracking limit states was accurately predicted by pre-test linear and nonlinear finite element (FE) models. At overload conditions, the baseline SFRC-only segment exhibited a radial bursting failure. The inclusion of supplemental conventional reinforcement does not reduce the level of cracking damage or strain development below the TBM’s ultimate jacking capacity; however, at overload conditions, the supplemental reinforcement mitigates cracking and prevents a radial bursting failure at 20.3 MN per pad. A load eccentricity of 38 mm towards the extrados surface increased the transverse strain and the formation of transverse cracking at a lower load level.

Impact of Calcium Eccentricity on the Safety and Effectiveness of Coronary Intravascular Lithotripsy: Pooled Analysis From the Disrupt CAD Studies.

Coronary intravascular lithotripsy (IVL) safely facilitates successful stent implantation in severely calcified lesions. This analysis sought to determine the relative impact of lesion calcium eccentricity on the safety and effectiveness of IVL using high-resolution optical coherence tomography imaging. Individual patient-level data (n=262) were pooled from 4 distinct international prospective studies (Disrupt CAD I, II, III, and IV) and analyzed by an independent optical coherence tomography core laboratory. IVL performance in eccentric versus concentric calcification was analyzed by dividing calcified lesions into quartiles (≤180° [most eccentric], 181°-270°, 271°-359°, and 360° [concentric]) by maximum continuous calcium arc. In the 230 patients with clear imaging field on optical coherence tomography, there were no differences in preprocedure minimum lumen area, diameter stenosis, or maximum calcium thickness. The calcium length and volume index increased progressively with increasing mean and maximum continuous calcium arc (ie, concentricity). Conversely, the minimum calcium thickness decreased progressively with increasing concentricity. Post-procedure, the number of calcium fractures, fracture depth, and fracture width increased with increasing concentricity, with a 4-fold increase in the number of fractures in lesions with 360° of calcium arc compared with ≤180°. This increase in IVL-induced calcium fracture with increasing calcium burden and concentricity facilitated stent expansion and luminal gain such that there were no significant differences across quartiles. IVL induced calcium fractures proportional to the magnitude of coronary artery calcium, including in eccentric calcium, leading to consistent improvements in stent expansion and luminal gain in both eccentric and concentric calcified coronary lesions.

Water flow rate quantification through an experimental CNT membrane: A molecular dynamics simulation approach

The comprehension of water flow rate within carbon nanostructures holds great importance in both theoretical understanding and engineering design of microscale and nanoscale devices. This study presents a comprehensive numerical model for analyzing the water flow rate in Carbon Nanotube (CNT) membranes. The outcomes of this model have particular relevance in predicting the performance and designing CNT membranes for water desalination, which offer the potential for remarkably rapid transport. By investigating the characteristics of the CNT membrane, various geometric properties that influence the overall flow rate are quantified. Apart from the diameter and length, attention is also given to non-ideal factors associated with the deformation of CNTs from their original structures. Specifically, the impact of eccentricity and bending on the flow rate through CNTs is examined, revealing limited but noteworthy effects. Additionally, a simplified model is developed to characterize the membrane using statistical data pertaining to CNT synthesis. The results of the total water flow rate demonstrate that the existing numerical model closely aligns with the reported experimental values.

Effects of collar eccentricity on azimuthal response characteristics for acoustic reflection measurement while drilling

Acoustic reflection imaging has been successfully applied in postdrilling wireline logging, and the technique is potentially more valuable in acoustic logging while drilling (ALWD), particularly in geosteering while drilling. Because of the common occurrence of tool eccentering in drilling, the impact of drill collar eccentricity on the acoustic wavefield inside and outside the borehole must be considered. Therefore, we analyze the effect of an eccentric drill collar on acoustic reflection imaging while drilling using analytical solutions in a dual-cylindrical coordinate system. The virtual source analogy and the translational addition theorem for cylindrical Bessel functions are used to calculate the response of the fluid-filled borehole with an eccentric collar to the incident wavefield from a formation reflector. The analysis results are validated with those from 3D finite-difference simulations. We also have studied the azimuthal variation of the received wavefield and compared the results with their centralized counterparts, for which the effects of collar eccentricity, frequency of the source, and formation elastic property are analyzed. The results indicate that the asymmetric feature of the wavefield due to the eccentric collar allows for determining the azimuth of the reflector, providing a solution to the azimuth ambiguity problem of borehole acoustic reflection imaging. Our results, besides developing an effective method for eccentric collar ALWD modeling, can be used to provide a theoretical foundation for ALWD tool development and data interpretation.

Research on torsional stiffness of flexspline-flexible bearing contact pair in harmonic drive based on macro-micro scale modeling

The flexspline and flexible bearing constitute a critical contact pair in a harmonic drive system, and their torsional stiffness has a significant impact on the performance characteristics manifested by the harmonic drive. In this study, a micro scale three-dimensional fractal model was combined with a macro scale finite element simulation method to establish an equivalent torsional stiffness model for the flexspline-flexible bearing contact pair (FS-FB contact pair), which enables the theoretical prediction of the torsional stiffness of this contact pair. A torsional stiffness testing platform was constructed for a harmonic drive, and the consistency between the experimental results of the torsional stiffness curve and the theoretical predictions validates the effectiveness of the proposed model. The influences of torque, installation eccentricity, and deformation coefficient on the torsional stiffness of the FS-FB contact pair were also discussed. The results indicate that the torsional stiffness of the FS-FB contact pair increases nonlinearly with an increase in torque. On the other hand, the torsional stiffness of the FS-FB contact pair decreases with an increase in installation eccentricity, and increases before subsequently decreasing with an increase in deformation coefficient. Moreover, as torque increases, the impact of installation eccentricity and deformation coefficient on the torsional stiffness diminishes. This article provides a theoretical reference for the optimization design and performance enhancement of harmonic drives.

Impact of Scleral Lens Front Surface Eccentricity on Visual Acuity, Contrast Sensitivity, and Higher-Order Aberrations in Eyes With Keratoconus.

To investigate the effect of front surface eccentricity (FSE) of scleral lenses (SLs) on corrected distance visual acuity (CDVA), contrast sensitivity (CS), and higher-order aberrations (HOAs) in keratoconic eyes. Fifteen keratoconic eyes fitted with BostonSight SCLERAL lenses of different eccentricity values (FSE0=0, FSE1=0.30, and FSE2=0.60). CDVA, CS, and HOAs were measured at baseline and after 30 min of SL wear. CDVA and CS were measured with the Early Treatment Diabetic Retinopathy Study and Pelli-Robson chart, respectively, and iTrace aberrometer was used to evaluate the HOAs. Baseline CDVA was 0.30±0.29, which significantly improved to 0.10±0.11, 0.05±0.06, and 0.05±0.08 logMAR with FSE0, FSE1, and FSE2, respectively ( P <0.05). The post hoc showed no significant difference between eccentricities. Baseline CS was 1.19±0.47, which improved to 1.54±0.12, 1.59±0.10, and 1.60±0.11 with FSE0, FSE1, and FSE2, respectively ( P <0.01), but post hoc showed no significant difference between eccentricities. A statistically significant reduction was found in HOAs when compared with baseline ( P <0.01). Comparison between eccentricities showed a significant difference only between FSE0 and FSE1 for RMS coma ( P =0.01) and RMS spherical aberrations ( P =0.004) where FSE1 showed better performance in reducing HOAs compared with FSE0. HO-RMS, RMS secondary astigmatism, and RMS trefoil showed no significant difference between eccentricities, but FSE1 and FSE2 performed superior to FSE0. BostonSight SCLERAL lenses with varying eccentricities corrected a significant amount of HOAs and improved CDVA and CS in keratoconus patients. Practitioners should be aware of this distinct feature of SLs and use it as needed to improve visual performance.

A numerical simulation of a droplet impacting a small superhydrophobic cylinder eccentrically

Droplet collisions on superhydrophobic cylindrical surfaces are widely seen in industrial applications. To investigate their dynamic behavior, numerical simulations of droplets impacting eccentrically on the surface of a small superhydrophobic cylinder are performed in this work. The eccentricity e ranges from 0 to 1.2 mm, and the impact velocity ranges from 0.5 to 2 m/s. The effects of the impact velocity and eccentricity are studied in detail. The results show that increasing the eccentricity e reduces the maximum spreading factor and exacerbates the asymmetry of droplets in the azimuthal direction. When the droplets impact on the small cylindrical surface, two collision modes are observed: an asymmetric stretching regime and a stretched rebound regime. The formulation (Wecr/D∗=230ε+31) is employed as a criterion to distinguish between the two modes. With increasing eccentricity e, an asymmetrical flow of droplets from the non-impact side to the impact side occurs, accompanied by a transition in the dynamic behavior of the droplets from stretching to bouncing. The asymmetrical stretching and stretched rebound can effectively decrease the contact time between the droplet and the cylindrical surface, resulting in a reduction of up to 32% during eccentric impact.

Prediction of Tool Eccentricity Effects on the Mechanical Properties of Friction Stir Welded AA5754-H24 Aluminum Alloy Using ANN Model.

The current study uses three different pin eccentricities (e) and six different welding speeds to investigate the impact of pin eccentricity on friction stir welding (FSW) of AA5754-H24. To simulate and forecast the impact of (e) and welding speed on the mechanical properties of friction stir welded joints for (FSWed) AA5754-H24, an artificial neural network (ANN) model was developed. The input parameters for the model in this work are welding speed (WS) and tool pin eccentricity (e). The outputs of the developed ANN model include the mechanical properties of FSW AA5754-H24 (ultimate tensile strength, elongation, hardness of the thermomechanically affected zone (TMAZ), and hardness of the weld nugget zone (NG)). The ANN model yielded a satisfactory performance. The model has been used to predict the mechanical properties of the FSW AA5754 aluminum alloy as a function of TPE and WS with excellent reliability. Experimentally, the tensile strength is increased by increasing both the (e) and the speed, which was already captured from the ANN predictions. The R2 values are higher than 0.97 for all the predictions, reflecting the output quality.

Dynamic characteristics of droplet eccentrically impacting on the surface of a hydrophilic cylinder

Droplet impact widely exists in a variety of industrial application, and its dynamic characteristics have a significant effect on the system efficiency. In this study, the behavior characteristics of droplets impacting hydrophilic wires are carried out by combining experiments and numerical simulations. Ignore the airflow disturbance in the environment, the effects of eccentricity, Weber number and Reynolds number on droplet morphology evolution under the condition of fixed size ratio of droplet/cylinder are analyzed, and the flow characteristics of central and eccentric impact of droplets are compared. The results show that the eccentricity, the Weber number and the Reynolds number of the droplets have significant effects on the dynamic characteristics of the droplets. With the increase of the eccentricity, the maximum spreading coefficient gradually increases, and there are four typical modes: symmetrical spreading-wrapping, asymmetric spreading-wrapping, unilateral wetting and partial wetting. When the Weber number is 51, the droplet spreading and retracting behavior is obvious. With the increase of Weber number, the droplet impact spreading velocity is accelerated, and the maximum spreading coefficient is gradually increased. With the increase of the eccentricity or the decrease of the Reynolds number, the instability of the spreading of the liquid film increases, and the droplet is more difficult to be caught by the wire.

Eccentric impact of a submillimeter sphere on droplet surface under electric field

Eccentric impact of a submillimeter sphere on droplet surface under electric field

Performance Assessment in a “Lane Departure” Scenario of Impending Collision for an ADAS Logic Based on Injury Risk Minimisation

The current prioritisation of road safety enhancement in the automotive sector is leading toward the near future implementation of Advanced Driver Assistance Systems (ADASs), aiming at the simultaneous intervention of braking and steering for impact avoidance in case of an impending collision. However, it is partially unclear how new technologies for controlling the steering will actually behave in the case of inevitable collision states; the need consequently emerges to propose and tune efficient ADAS strategies to handle the complexity of critical road scenarios. An adaptive intervention logic on braking and steering for highly automated vehicles is applied in the context of a “lane departure”, two-vehicle critical road scenario; the ADAS implementing the logic activates to minimise the injury risk for the ego vehicle’s occupants at each time step, adapting to the eventual scenario evolution consequent to actions by other road users. The performance of the adaptive logic is investigated by a software-in-the-loop approach, varying the mutual position of the involved vehicles at the beginning of the criticality and comparing the injury risk outcomes of the eventual impacts with those connected to the Autonomous Emergency Braking (AEB). The results highlight a twofold benefit from the adaptive logic application in terms of road safety: (1) it decreases the frequency of impacts compared to the AEB function; (2) in inevitable collision states, it decreases injury risk for the vehicles’ occupants down to 40% compared to the AEB. This latter condition is achieved thanks to the possibility of reaching highly eccentric impact conditions (low impact forces and occupants’ injury risk as a consequence). The obtained highlights expand the literature regarding the adaptive logic by considering a diverse critical road scenario and investigating how fine variations on the vehicles’ mutual position at the beginning of the criticality reflect on the injury outcomes for different types of intervention logic.