Direct Influence Research Articles

Simulation Analysis of the Annular Liquid Disturbance Induced by Gas Leakage from String Seals During Annular Pressure Relief

Due to the failure of string seals, gas can leak and result in the abnormal annulus pressure in gas wells, so it is necessary to relieve the pressure in gas wells. In the process of pressure relief, the leaked gas enters the annulus, causes a the great disturbance to the annulus flow field, and thus reduces the protection performance of the annular protection fluid in the string. In order to investigate the influence of gas leakage on the annular flow field, a VOF finite element model of the gas-liquid two-phase flow disturbed by gas leakage in a casing was established to simulate the transient flow field in the annular flow disturbed by gas leakage, and the influences of leakage pressure differences, leakage direction, and leakage time on annular flow field disturbance and wall shear force were analyzed. The analysis results showed that the larger leakage pressure difference corresponded to the faster diffusion rate of the leaked gas in the annulus, the faster the flushing rate of the leaked gas against the casing wall, and a larger shear force on the tubing wall was detrimental to the formation of the corrosion inhibitor film on the tubing wall and casing wall. Under the same conditions, the shear action on the outer wall of tubing in the leakage direction of 90° was stronger than that in the leakage directions of 135° and 45° and the diffusion range was also larger. With the increase in leakage time, leaked gas further moved upward in the annulus and the shear effect on the outer wall of tubing was gradually strengthened. The leaked acid gas flushed the outer wall of casing, thus increasing the peeling-off risk of the corrosion inhibitor film. The study results show that the disturbance law of gas leakage to annular protection fluid is clear, and it was suggested to reduce unnecessary pressure relief time in the annulus to ensure the safety and integrity of gas wells.

Triglyceride-glucose Index and Its combination with obesity indicators mediating the association between 2-hydroxyfluorene and the prevalence of cardiovascular disease: Evidence from the NHANES (2005–2018)

BackgroundPolycyclic aromatic hydrocarbons (PAHs) were increasingly recognized as a group of environmental pollutants associated with various health issues. The rise in their prevalence in the environment was concerning. Yet, the effects of PAH exposure on cardiovascular diseases (CVDs) were still not well understood. PurposeThis study investigated the impact of exposure to 2-hydroxyfluorene on CVDs prevalence, with a special focus on the mediating role of triglyceride-glucose (TyG) index and its combination with obesity indicators. MethodUsing National Health and Nutrition Examination Survey (NHANES) data from 2005 to 2018, this study assessed how 2-hydroxyfluorene affects CVDs prevalence through various statistical techniques. The investigation began with restricted cubic spline (RCS) analysis to explore the relationship between 2-hydroxyfluorene levels and CVDs prevalence. Logistic regression was then used to examine associations within PAH mixtures, alongside the Bayesian Kernel Machine Regression (BKMR) model. Furthermore, the Quantile G-Computation (QG-comp) model was used to evaluate the influence of weights and directions. A mediation analysis was also performed to assess the mediating role of TyG-related indicators on the relationship between 2-hydroxyfluorene and CVDs prevalence. Besides, the association between 2-hydroxyfluorene and the prevalence of each specific CVDs, congestive heart failure, myocardium infarction, angina pectoris and coronary heart disease, was also assessed and so was the mediated effect. Finally, the subgroup analysis was conducted to assess the association in each specific subgroup. ResultThe study, involving 3645 participants, found a significant positive association between 2-hydroxyfluorene exposure and CVD (OR (95 %CI) = 115.8013 (5.0521 ∼ 2654.3248), P=0.0029), with 2-hydroxyfluorene showing the positive contribution to CVDs prevalence within the phthalate mixture. The positive association also existed between 2-hydroxyfluorene and the prevalence of each specific CVDs. TyG and TyGWC (Triglyceride Glucose-Waist Circumference) were identified as mediators in the link between 2-hydroxyfluorene exposure and the prevalence of total CVD and each specific CVD, while TyGBMI (Triglyceride Glucose-Body Mass Index) can only mediate the association between 2-hydroxyfluorene and the prevalence of total CVD, congestive heart failure and angina pectoris ConclusionThe findings highlighted a significant association between 2-hydroxyfluorene exposure and CVDs prevalence, with TyG-related indicators acting as mediators.

Three-Dimensional Organotypic Systems for Modelling and Understanding Molecular Regulation of Oral Dentogingival Tissues

Three-dimensional organotypic models benefit from the ability to mimic physiological cell–cell or cell–matrix interactions and therefore offer superior models for studying pathological or physiological conditions compared to 2D cultures. Organotypic models consisting of keratinocytes supported by fibroblasts embedded in collagen matrices have been utilised for the study of oral conditions. However, the provision of a suitable model for investigating the pathogenesis of periodontitis has been more challenging. Part of the complexity relates to the different regional epithelial specificities and connective tissue phenotypes. Recently, it was confirmed, using 3D organotypic models, that distinct fibroblast populations were implicated in the provision of specific inductive and directive influences on the overlying epithelia. This paper presents the organotypic model of the dentogingival junction (DGJ) constructed to demonstrate the differential fibroblast influences on the maintenance of regionally specific epithelial phenotypes. Therefore, the review aims are (1) to provide the biological basis underlying 3D organotypic cultures and (2) to comprehensively detail the experimental protocol for the construction of the organotypic cultures and the unique setup for the DGJ model. The latter is the first organotypic culture model used for the reconstruction of the DGJ and is recommended as a useful tool for future periodontal research.

Influence of different vibration directions on the solder layer fatigue in IGBT modules

Insulated-gate bipolar transistor (IGBT) modules are extensively utilized in high-speed trains, ships, and electric vehicles. Compared to those used in power systems, IGBT modules in these applications are more susceptible to vibration effects on their reliability. This paper proposes a multi-physics field simulation method and a lifetime model for IGBT modules to assess the impact of different vibration directions on solder layer fatigue. Initially, a multi-physics field model of the IGBT module is developed, incorporating electrical, thermal, mechanical, and vibration coupling. The effectiveness of this multi-physics simulation model is verified by an experimental platform. Subsequently, the influence of different vibration directions on solder layer fatigue in the IGBT module is analysed, and a life model of the IGBT is proposed through simulation. Finally, a power cycling with a vibration environment experimental platform is established to validate the effect of vibration on solder layer fatigue in the IGBT module. The simulation and experimental results indicate that vertical vibration accelerates the solder layer fatigue of IGBT modules, and the lifetime of an IGBT module operating under vertical vibration at 30 Hz is about 15 % shorter than that of an IGBT module operating under power cycling alone. The error between the calculated results of the solder layer failure and the experimental result is <5 %.

Influence of velocity pulse directivity on seismic response of cross-fault bridges

Pulse-type ground motions have special destructive effects on structures, and directivity is one of the fundamental characteristics of velocity pulses. In this paper, the impact of the velocity pulse directivity of seismic motions on both sides of the fault on the seismic response of fault-crossing bridges was quantified using the original records from the Chi-Chi earthquake in Taiwan. First, an automatic baseline correction method was applied to restore the permanent ground displacement, and the direction corresponding to the strongest pulse energy on both sides of the fault was identified based on continuous wavelet transformation. On this basis, the variability of the peak intensity of ground motions on the hanging wall and footwall in different directions, as well as the differences in pulse characteristics between the strongest pulse component and the two initial horizontal components, were analysed. Finally, a typical 5 × 30 m continuous girder bridge was considered as the research object to reveal the influence of the velocity pulse directivity on the seismic response of key parts on both sides of the fault. The results showed that the variability in the peak ground-motion intensity on the hanging wall of the fault was higher than that on the footwall. The displacement variability was up to 863 %, velocity was 262 %, and acceleration was 124 %. The pulse characteristics of the strongest pulse component were stronger than those of the parallel and vertical fault components, and its acceleration, velocity, and displacement response spectra were larger. The amplification effects of the velocity pulse directivity on the transverse bending moment, longitudinal bending moment, and torque of the pier bottom reached 1.3, 1.1, and 1.6, respectively. However, the amplification effect of the velocity pulse directivity on the relative displacement of the pier top, displacement of the main beam, and displacement of the bearing was more than 1.6 times, which was more significant than the internal force of the pier bottom.

On the influence of AVAS directivity on electric vehicle speed perception

Electric vehicles (EVs) typically produce minimal noise at low driving speeds, increasing the risk of accidents for pedestrians and other vulnerable road users. Therefore, regulations require EVs to use acoustic vehicle alerting systems (AVAS) that emit artificial warning sounds. Investigating the human response to these AVAS sounds requires laboratory listening experiments, often based on auralizations. One of the challenges when auralizing electric vehicles is to include AVAS radiation directivity. However, it is currently unknown how this directivity affects the perception of a vehicle passing by and whether an accurate reproduction is necessary for auralizations. We present a study on the influence of AVAS directivity on perceived vehicle speed, comparing different radiation patterns in combination with narrowband and tonal AVAS signals in a paired comparison listening experiment with 31 participants. The results show that AVAS radiation directivity can significantly influence the perception of vehicle pass-by speed, with a tendency for omnidirectional patterns to be perceived slower than more directional patterns. Additionally, most participants consistently rated either the tonal or the narrowband noise AVAS signal as faster throughout most comparisons. This indicates that AVAS signal type can affect vehicle speed perception with a subjective preference between tonal and narrowband noise AVAS.

Fluid–structure interaction simulations of wind gusts impacting a hyperbolic paraboloid tensile structure

The paper focuses on fluid–structure interactions (FSI) between a turbulent, gusty fluid flow, and a membrane structure. Lightweight structures are particularly vulnerable to wind gusts and can be completely destroyed by them, making it essential to develop and evaluate numerical simulation methods suited for these types of problems. In this study, a thin-walled membrane in the shape of a hyperbolic paraboloid (hypar) is analyzed as a real-scale example. The membrane structure is subjected to discrete wind gusts of varying strength from two different directions. A partitioned FSI approach is employed, utilizing a finite-volume flow solver based on the large-eddy simulation technique and a finite-element solver developed for shell and membrane structures. A recently proposed source-term formulation enables the injection of discrete wind gusts within the fluid domain in front of the structure. In a step-by-step analysis, first the fluid flow around the structure, initially assumed to be rigid, is investigated, including a grid sensitivity analysis. This is followed by examining the two-way coupled FSI system, taking the flexibility of the membrane into account. Finally, the study aims to assess the impact of wind gusts on the resulting deformations and the induced stresses in the tensile material, with a particular focus on the influence of different wind directions.

The Subjective Dimension of a Journalist’s Professional Culture

The article is devoted to the professional culture of modern journalists as a dynamic phenomenon that has become the subject of discussion in the media employees’ corporation and the academic community. In this regard, the authors review the contradictory experts’ opinions on the future of the world and domestic press. The originality of the presented research is that the issues are considered from the journalists’ subjective point of view. For this purpose, the special technique of semi-structured in-depth interviews with acting editorial workers was developed as a part of a comprehensive research project “Professional Ideology of Journalism” organized by the Department of Theory of Journalism and Mass Communications of St. Petersburg State University. The results of the performed procedures are described in the article. Hypothetically, the authors assumed that, in a subjective dimension, the existing knowledge on the professional culture of a journalist and, in particular, the normative ideas on it would be noticeably corrected. Accordingly, the purpose of the study is to identify the real diversity of journalists’ subjective views on the profession and their position in it, as far as this is achievable within the framework of a particular research project. The analysis of the interview materials showed that the ideas and skills of media employees are formed without the direct infl uence of standards adopted in the global and national community, they are formed mainly on the basis of personal experience and communication in the industrial environment. Thus, culture gets a lot of subjective versions. This means that in the process of transformation of current journalism, individual creativity is enhanced, which is especially typical for the younger generation. On the other hand, the contours of the profession become blurred at the ideological, instrumental, and ethical levels. The authors of the article support regular discussions of the problems of the profession, which will contribute to the removal of emerging contradictions and to mutual understanding between generations. Keywords: professional culture of a journalist, subjective view, in-depth interview, standards, diversity

Seismic vulnerability analysis of hospitals and school buildings considering the Gaussian regression algorithm

This study combines the Gaussian regression algorithm to propose a nonlinear regression model that can be used to evaluate the seismic vulnerability of regional hospitals and school buildings. The failure features and disaster mechanisms of hospital and school buildings affected by the Jishishan (JSS) earthquake on December 18, 2023, and the Wenchuan (WC) earthquake on May 12, 2008, were reported. The samples of 252 damaged buildings (37 hospitals and 215 schools) in Dujiangyan city affected by the Wenchuan earthquake for which the author participated in the survey were collected and counted. Hospitals and school buildings were classified according to the types of reinforced concrete (RC) and masonry structures, and earthquake vulnerability probability matrices for hospital and school building clusters were established considering the actual failure probabilities. A total of 2103,213 acceleration records (from the Wenchuan earthquake) monitored by 12 real stations were selected. Using dynamic time history and response spectrum analysis methods, time history and spectrum curves were generated, considering the influence of different seismic directions. Using the developed Gaussian regression model, vulnerability comparison curves and parameter matrices considering multiple regression algorithms were generated. This paper considers the effects of the construction year and number of floors on the seismic vulnerability of hospital and school buildings. Seismic vulnerability curves and failure probability matrices were generated and established on the basis of actual structural failure probabilities. According to regression and vulnerability surface analysis, the evaluation results of the proposed model are highly consistent with actual field observations.

Entrepreneurial intention among Colombian university students: A theory of planned behavior analysis in Colombia

Studies on entrepreneurship have used several approaches, among which, research on entrepreneurial intention (EI) can be highlighted. Studies on EI help researchers better understand entrepreneurial behavior. In this sense, one of the most relevant frameworks in EI studies is the Theory of Planned Behavior (TPB), which stands out for its predictive capacity, mainly in a university context. The aim of this research was to determine the relationship between the variables of Personal Attitudes (PAs), Subjective Norms (SNs), and Perceived Behavioral Control (PBC) with respect to the EI of university students in Colombia. For this purpose, we constructed a model that integrates the elements of the TPB with EI with reference to the validated instrument of the Global University Entrepreneurial Spirit Student's Survey (GUESSS) project applied to a sample of 12,383 students. The estimation of the model uses structural equations (SEMs) by means of Partial Least Squares-Path Modelling (PLS-PM). The findings show that PAs and PBC are determinants of EI, while SNs have no direct influence; however, their effects are indirect. These results have implications for how to promote entrepreneurship in emerging economies through the university environment. The results indicate that the development of students' capabilities is essential for entrepreneurship and its incorporation into the university's knowledge transfer model.

The Influence of Open-Ground Floors on the Impact of RC Columns Due to Seismic Pounding from Adjacent Lower-Height Structures

The substantial influences of masonry infills used as partition walls on the seismic behavior of multistory reinforced concrete (RC) structures have long been recognized. Thereupon, in this study, considering open-ground floors due to a lack of infills (pilotis configuration), the structural pounding phenomenon between adjoining RC buildings with unequal story levels and unequal total heights is investigated. Emphasis is placed on the impact of the external columns of the higher structure, which suffer from the slabs of adjoining shorter buildings. The developing maximum shear forces of the columns due to the impact are discussed and compared with the available shear strength. Furthermore, it is stressed that the structures are partially in contact, as is the case in most real adjacent structures; therefore, the torsional vibrations brought about due to the pounding phenomenon are examined by performing 3D nonlinear dynamic analyses (asymmetric pounding). In this study, an eight-story RC frame structure that is considered to be fully infilled or has an open-ground floor interacts with shorter buildings with ns stories, where ns = 6, 3, and 1. Two natural seismic excitations are used, with each one applied twice—once in the positive direction and once in the negative direction—to investigate the influence of seismic directionality on the asymmetric pounding effect. Finally, from the results of this study, it is concluded that the open-ground story significantly increases the shear capacity demands of the columns that suffer the impact and the inelastic rotation demands of the structure, whereas these demands further increase as the stories of the adjoining shorter building increase.

About this title - The Impacts of Igneous Systems on Sedimentary Basins and their Energy Resources

Igneous processes within sedimentary basins impact energy resource plays across a range of scales from regional tectonics to reservoir porosity. Understanding these interactions has a direct influence on hydrocarbon, carbon capture, geothermal, hydrogen and helium projects. This volume demonstrates state of the art thinking around these often complex systems.

Influence of Field Direction and Conductor Aspect Ratio on Coupling Losses: Measurements and Modeling on the JT-60SA TF Conductor

Influence of Field Direction and Conductor Aspect Ratio on Coupling Losses: Measurements and Modeling on the JT-60SA TF Conductor

Assessment of the seismic failure of reinforced concrete structures considering the directional effects of ground motions

Seismic intensity measures at different levels significantly impact the seismic damage of building clusters. Reinforced concrete (RC) structures are a type of building widely used in different regions worldwide. A large amount of field seismic damage observation data indicates that within the same seismic intensity zone, the directional effects of varying ground motions lead to significant differences in damage to RC structures on different floors. However, relatively little research has been conducted on estimating the seismic fragility and vulnerability of RC structures considering the directional effects of seismic action. To further study the directional effect of seismic motion on the damage of different floors, this study conducted dynamic time history and spectral analyses on 1472,379 acceleration records in multiple directions obtained from monitoring at nine actual seismic stations during the 2008 Wenchuan earthquake in China. This paper innovatively reports on the actual damage features of RC structures during the Mw6.2 magnitude Jishishan earthquake in Gansu Province, China, on December 18, 2023 (the most severe destructive earthquake in China in 2023) and analyses the influence of earthquake directionality on the damage to different floors of RC structures. A three-dimensional numerical model of a four-story RC frame structure was established using numerical simulation and the finite element method. Different intensity measures were taken to input seismic excitations of different intensities into the RC structure in the 0°, 30°, 60°, and 90° directions, and damage simulation analysis was conducted. The nonlinear dynamic time history curves of structures under multiple directions of seismic excitation in different intensity zones have been developed. Using the interstory stiffness and interstory displacement angle as engineering demand parameters, damage assessment curves and stress clouds for RC structures with 1–4 floors considering different seismic directional effects were generated. The analysis results and major findings indicate that the seismic sequence in the 0° direction has a relatively heavy impact on the first floor of the RC structure in zone IX, which is consistent with the actual field observation results.

Unraveling the dynamics of password manager adoption: a deeper dive into critical factors

Purpose The purpose of this study is to comprehensively explore the password manager adoption landscape, delving into crucial factors such as performance, trust, social influence, self-efficacy, risk perception, security concerns, enjoyment and facilitating conditions. It also aims to contribute meaningful insights to security product research and practice. Design/methodology/approach A survey was used to investigate the characteristics of adoption intention for password managers. In total, 156 participants from a public university located in the Midwest region of the USA voluntarily completed the survey. Partial least squares structural equation modeling was used to estimate and validate causal relationships and the proposed research model. Findings Through empirical validation, this study demonstrates that constructs such as social influence, web-specific self-efficacy and perceived risk directly impact trust in password managers. Facilitating conditions and perceived security controls are identified as direct influencers on performance expectancy, deviating from the pathways of the traditional framework. Moreover, the model introduces novel elements crucial for comprehending password manager adoption, including “web-specific self-efficacy” and “perceived security control.” Originality/value The paper systematically reviews existing research on password managers, shedding light on crucial factors significantly influencing adoption behavior. By introducing deviations from conventional frameworks and theories, the study emphasizes the innovative nature of its model. It also formulates strategies to catalyze wider adoption and promote effective design of password managers, increasing user engagement rates.

Influence of the direction of ferrite-austenite banding on hydrogen embrittlement of 2205 duplex stainless steel

In this study, the fracture behavior of 2205 duplex stainless steel (DSS) under in-situ hydrogen charging is evaluated. For this purpose, fracture toughness tests are performed on single-edge notched bending specimens, in which hydrogen is introduced electrochemically in-situ, using an acid and a saline electrolyte at different current densities. The hydrogen content of both electrochemically and gaseous pre-charged specimens is measured to assess the influence of the aggressiveness of the environment. Three environments are evaluated: realistic, severe and highly severe. As the microstructure of DSS is characterized by the presence of ferrite and austenite bands, the influence of directionality on fracture toughness is also studied. For this purpose, specimens are machined in two directions, being crack growth parallel to the bands in one case, while crack growth is perpendicular to the bands in the other case. Fracture toughness was found to decrease with increasing current density and in a more aggressive environment, and to increase when crack growth was perpendicular to the bands. The fracture surface was also evaluated, revealing splits in the direction of the bands in all in-situ tests. The origin and propagation of these splits were studied using electron backscatter diffraction scans, concluding that splits propagated through the ferrite-austenite interface.

Towards Sustainable Living through Thermoneutral Temperature Management in Subtropical Steppe Climates

This study addresses the critical interplay between sustainable living and thermal comfort within residential buildings in subtropical steppe (BSh) climates, particularly in Northern Iraq. With the global imperative to enhance energy efficiency and occupant well-being, this research emphasizes the identification of thermoneutral indoor air temperature ranges that both support sustainable energy use and ensure the occupants’ thermal comfort. By analyzing the acceptable temperature limits across different building orientations during summer and winter, the study utilizes the predicted mean vote–predicted percentage dissatisfied (PMV-PPD) index approach to establish thermal comfort thresholds. The findings reveal that the optimal summer and winter indoor air temperatures are 29.2 °C and 19.4 °C, respectively, with variations across orientations highlighting the significant influence of building directionality on achieving thermoneutral conditions. A wider range of accepted temperatures exists in the eastward orientation in summer (between 26.6 °C and 29.2 °C). The study advances our understanding of sustainable thermal comfort practices, proposing orientation-specific temperature ranges as a cornerstone for reducing energy consumption without compromising occupant comfort in subtropical steppe climates.

Evaporation Dynamics on a Lithium Niobate Surface.

Manipulating the water evaporation dynamics is a prerequisite in various modern-day applications like DNA stretching, rapid disease diagnostics, and inkjet printing. One method to affect the evaporation dynamics of droplets is to externally apply electric fields. However, surfaces that bear an intrinsic surface charge have not yet been investigated with respect to their evaporation behavior. In this study, we investigate water droplet evaporation on lithium niobate (LN), a ferroelectric material with a very high spontaneous polarization of 0.7 . Our results show that a droplet deposited on an LN surface evaporates in three stages: (i) constant contact radius (ii) mixed phase (iii) stick-slip, which is likely originating from the intrinsic surface charge. The influence of the polarization direction of the LN surface as well as the relative humidity of the environment on various evaporation characteristics were studied. The results suggest that the specific adsorption layers forming on charged surfaces, e. g. from the humidity of the surrounding air, play a key role in the evaporation process. Furthermore, compared to other materials with similar contact angles, LN demonstrated a significantly large evaporation rate. This property might also be attributed to the intrinsic surface charge and could be exploited in heat transfer applications.

Anesthetic Mechanisms: Synergistic Interactions With Lipid Rafts and Voltage-Gated Sodium Channels.

Despite successfully utilizing anesthetics for over 150 years, the mechanism of action remains relatively unknown. Recent studies have shown promising results, but due to the complex interactions between anesthetics and their targets, there remains a clear need for further mechanistic research. We know that lipophilicity is directly connected to anesthetic potency since lipid solubility relates to anesthetic partition into the membrane. However, clinically relevant concentrations of anesthetics do not significantly affect lipid bilayers but continue to influence various molecular targets. Lipid rafts are derived from liquid-ordered phases of the plasma membrane that contain increased concentrations of cholesterol and sphingomyelin and act as staging platforms for membrane proteins, including ion channels. Although anesthetics do not perturb membranes at clinically relevant concentrations, they have recently been shown to target lipid rafts. In this review, we summarize current research on how different types of anesthetics-local, inhalational, and intravenous-bind and affect both lipid rafts and voltage-gated sodium channels, one of their major targets, and how those effects synergize to cause anesthesia and analgesia. Local anesthetics block voltage-gated sodium channel pores while also disrupting lipid packing in ordered membranes. Inhalational anesthetics bind to the channel pore and the voltage-sensing domain while causing an increase in the number, size, and diameter of lipid rafts. Intravenous anesthetics bind to the channel primarily at the voltage-sensing domain and the selectivity filter, while causing lipid raft perturbation. These changes in lipid nanodomain structure possibly give proteins access to substrates that have translocated as a result of these structural alterations, resulting in lipid-driven anesthesia. Overall, anesthetics can impact channel activity either through direct interaction with the channel, indirectly through the lipid raft, or both. Together, these result in decreased sodium ion flux into the cell, disrupting action potentials and producing anesthetic effects. However, more research is needed to elucidate the indirect mechanisms associated with channel disruption through the lipid raft, as not much is known about anionic lipid products and their influence over voltage-gated sodium channels. Anesthetics' effect on S-palmitoylation, a promising mechanism for direct and indirect influence over voltage-gated sodium channels, is another auspicious avenue of research. Understanding the mechanisms of different types of anesthetics will allow anesthesiologists greater flexibility and more specificity when treating patients.

Characterization of Magnetorheological Impact Foams in Compression.

This study focuses on the development and compressive characteristics of magnetorheological elastomeric foam (MREF) as an adaptive cushioning material designed to protect payloads from a broader spectrum of impact loads. The MREF exhibits softness and flexibility under light compressive loads and low strains, yet it becomes rigid in response to higher impact loads and elevated strains. The synthesis of MREF involved suspending micron-sized carbonyl Fe particles in an uncured silicone elastomeric foam. A catalyzed addition crosslinking reaction, facilitated by platinum compounds, was employed to create the rapidly setting silicone foam at room temperature, simplifying the synthesis process. Isotropic MREF samples with varying Fe particle volume fractions (0%, 2.5%, 5%, 7.5%, and 10%) were prepared to assess the effect of particle concentrations. Quasi-static and dynamic compressive stress tests on the MREF samples placed between two multipole flexible strip magnets were conducted using an Instron servo-hydraulic test machine. The tests provided measurements of magnetic field-sensitive compressive properties, including compression stress, energy absorption capability, complex modulus, and equivalent viscous damping. Furthermore, the experimental investigation also explored the influence of magnet placement directions (0° and 90°) on the compressive properties of the MREFs.