Mechanism Of Stress Generation Research Articles

A systematic review and Bayesian meta-analysis of 30 years of stress generation research: Clinical, psychological, and sociodemographic risk and protective factors for prospective negative life events.

Stress generation posits that (a) individuals at-risk for psychopathology may inadvertently experience higher rates of prospective dependent stress (i.e., stressors that are in part influenced by their thoughts and behaviors) but not independent stress (i.e., stressors occurring outside their influence), and (b) this elevated dependent stress, in some measure, is what places these individuals at-risk for future psychopathology. In recognition of 30 years of stress generation research, we conducted a systematic review and meta-analysis using frequentist and Bayesian approaches (102 articles with 104 eligible studies, N = 31,541). Generally strong support was found for psychopathology predicting dependent stress (e.g., dsOverall psychopathology = 0.36-0.52, BF₁₀ = 946.00 to 4.65 × 10¹⁸). Moderator analyses for dependent stress revealed larger effects for briefer assessments periods, shorter follow-ups, and self-report measures than for interviews. Among risk factors, depressogenic cognitive styles (ds = .26-.50, BF₁₀ = 47.50 to 1.00 × 10⁵) and general interpersonal vulnerability (ds = .26-.44, BF₁₀ = 2.72 to 2708.00) received the strongest support as stress generation mechanisms, and current evidence is modest for protective factors predicting dependent stress. Overall, larger effects were generally found for prospective prediction of dependent stress than independent stress. Evaluations of mediation in the research literature were relatively few, limiting the current review to qualitative analysis of the mediation component of stress generation. General support was found, however, for dependent stress as a mediator for psychopathology and associated risk factors in relation to subsequent psychopathology. The current review ends with recommendations for future research and integration of stress generation within minority stress frameworks. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Impact of temperature on residual stress and bonding in diamond-like carbon film: A molecular dynamics study under various deposition conditions

Diamond-like carbon (DLC) films exhibit excellent frictional properties; however, the high residual stress within the film, which causes detachment issues, limits their application in mechanical sliding surfaces. We have previously clarified via molecular dynamics (MD) simulations that the growth of sp3 clusters after the transition from sp2 to sp3 bonds during film formation causes the in-plane compressive stress in DLC films. In this study, we investigated whether this stress generation mechanism holds under various deposition conditions in the MD simulations, wherein incident energy, atomic flux, and substrate temperature were systematically changed. The results of the MD simulations consistently revealed that the compressive stress generation mechanism remains unchanged across different deposition conditions. With increasing incident energy and atomic flux and decreasing substrate temperature, in-plane compressive stress in the film increased owing to increased sp3 content. Conversely, when the incident energy was further increased, both stress and sp3 content decreased. Based on a molecular statistical calculation, it was shown that the stable bonding state changed from sp3 to sp2 at high temperatures. Because the temperature monotonically increased with increasing incident energy, it was concluded that the change in the stable bonding state caused the non-monotonic change in the stress and sp3 content at high temperatures.

Mechanism of stress generation at the epoxy-epoxy interface

Epoxy resins are widely used in power equipment, and due to the material as well as process requirements, multi-layer epoxy structures inevitably exist. The interlayer interface between epoxy layers, formed via secondary curing, causes a potential weak link in the material's properties. This work experimentally measures the temperature and strain at the epoxy-epoxy interface under various conditions, including the presence or absence of epoxy and differing chemical doses of curing agent. Subsequently, an epoxy-epoxy interface strain resin simulation model is established to examine the mechanism of interface stress formation by exploring the curing kinetics of epoxy resins using the Straink method. Experimental measurements and simulation calculations reveal the presence of an interaction between interlayer interfaces during the secondary curing. Changing the dose of curing agent in the post-pouring layer can change the interaction between the layers and regulate the interlayer interface performance.

Is everything really okay?: Using ecological momentary assessment to evaluate daily co-fluctuations in anxiety and reassurance seeking

ObjectiveReassurance seeking, a behavior prominent in anxiety disorders and depression, is associated with poorer quality of interpersonal relationships and acts as a mechanism of stress generation. However, little research has elucidated momentary associations between state anxiety and reassurance seeking behaviors. MethodIn a sample of 104 university-affiliated young adults, we sought to replicate cross-sectional associations of reassurance seeking with trait anxiety (Aim 1) and intolerance of uncertainty (Aim 2). We then used ecological momentary assessment (EMA) to evaluate concurrent fluctuations in daily anxiety and reassurance seeking across 14 consecutive days (Aim 3). Hierarchical multi-level models for intensive longitudinal data were used to evaluate the relationship between state anxiety and daily reassurance seeking. ResultsIn baseline analyses, trait anxiety and intolerance of uncertainty were significantly associated with greater trait reassurance seeking, controlling for depression. Analyses of the EMA data showed that daily reassurance seeking behaviors fluctuated concurrently with daily anxiety during the 14 days, while controlling for trait anxiety and depression. ConclusionGiven evidence of concurrent fluctuations between state anxiety and reassurance seeking, the behavior should be considered as a potential target in treatment for anxiety disorders.

Characteristics of residual stress distribution in wire-arc additive manufactured layers of low transformation temperature material

High heat input in wire and arc additive manufacturing (WAAM) tends to result in high tensile residual stress, which adversely affects performance and service reliability. However, low-transformation-temperature (LTT) materials are susceptible to compressive residual stresses due to their low phase-transformation point. Here, the LTT material 10Cr10Ni was used as the deposited material to fabricate a pipe structure, and the contour method was applied to measure the residual stress distribution in the cross-section. A thermomechanical coupling analysis model was developed to investigate the residual stress generation mechanism in 10Cr-10Ni(LTT) during the WAAM process. The simulated deformation and residual stress distributions agree well with the measurements. Through simulation analysis of the deposition of different layers, we found the key to the generation of compressive residual stresses in the LTT layers lies in whether there is a transformation from austenite to martensite during the final thermal cycle. When the deposition height exceeded 5.405 mm (approximately four layers), compressive residual stresses were only generated in the last four LTT layers and transformed into tensile residual stresses in the other layers. This results in a concept called the effective region, which can be used as a guide for reducing stress in WAAM using LTT materials.

Stress Relief in Metal Anodes: Mechanisms and Applications

AbstractMetal anodes (lithium/sodium/zinc) are recognized as the most promising choice for rechargeable batteries due to their high theoretical capacity and low electrochemical redox potential. Unfortunately, metal anodes face serious metal dendrite problems, hindering their practical applications. Recent research has shown that metal dendrites can also be caused by high levels of stress generated during the metal deposition process. To address this issue, an alternative strategy based on stress relief is proposed to inhibit the growth of metal dendrites. Herein, this work aims to investigate the mechanism of stress generation and evolution within metal anodes. In addition, this work explores the utilization of stress to induce metal nucleation. This work further discuss the various experimental techniques used to study stress release in metal dendrites and review recent research findings on stress relief in metal dendrites within metal anodes. Specifically, this work examines how microstructure and processing conditions affect stress release and discuss potential strategies for improving the efficiency of stress relief strategies in metal dendrites. As a result, a deeper understanding of stress release in metal dendrites can lead to the development of rechargeable batteries with superior performance, longer cycle life, as well as enhanced safety for practical applications in various fields.

Hot‐air drying of corn kernels: Drying kinetics and quality improvement

AbstractBackground and ObjectivesDuring the hot‐air drying process of corn kernels, excessive stress can cause cracks to develop. For this reason, it's essential to identify the optimum parameters that can minimize stress during hot‐air drying.FindingsIn this study, a three‐dimensional fitness model was established based on the average geometric size of corn kernels. Additionally, a hot‐air drying model was constructed on the basis of heat and mass transfer, stress‐strain theory, and conservation law of heat and mass transfer. Simulated calculations of heat and mass transfer were performed to obtain the temperature and moisture gradient distribution. This distribution was then coupled with a stress model to reveal the variation of drying stress. Verification experiments were conducted on the drying model. The results indicated that the temperature and moisture gradient were symmetrically distributed about the geometric center of corn kernels. At symmetrical positions about the geometric center, their sizes were almost equal but their directions are opposite. The thermal stress and moisture gradient stress showed the fact of larger surface but smaller interior of corn kernels. Furthermore, they both increased rapidly in the initial stage and then slowly decreased. The maximum value of thermal stress was 4.57 kPa, and the maximum value of moisture gradient stress was 0.49 MPa.ConclusionsMass transfer plays a significant role in the hot‐air drying process, and cracks can develop as a result of excessive moisture gradient stress. To mitigate these issues, it's important to increase the air humidity in a controlled manner to significantly reduce the total stress. The maximum error in temperature between simulated and experimental results was 8.5%. This suggests that our drying model can be effectively utilized to explore temperature gradient, moisture gradient, and stress distribution of corn kernels.Significance and NoveltyThis study provides insights into the mechanism of stress generation that occurs during the hot‐air drying process of corn kernels. Our analysis indicates that properly increasing the air humidity can significantly reduce drying stress and consequently prevent the formation of cracks. This ultimately leads to improved product quality and economic value.

Major gender differences in relations between life stressor frequency and gray matter in adolescence and emerging adulthood.

Adolescence and emerging adulthood is likely a sensitive period for the neural effects of stress due to increasing life stress, onset of stress-related disorders, and continued gray matter (GM) development. In adults, stress is associated with GM differences in the medial prefrontal cortex (mPFC), hippocampus, and amygdala, but little is known about these relations, and whether they differ by gender, during adolescence and emerging adulthood. Further, it is unknown whether dependent (self-generated) and independent (fateful) stressors have distinct associations with GM, as each have distinct relations with internalizing psychopathology. We tested relations between recent dependent and independent stressor frequency (ALEQ-R) and GM structure using MRI in a priori regions of interest (mPFC, amygdala, and hippocampus) and across the cortex in youth from the Denver/Boulder metro area ages 14-22 (N = 144). Across both genders, no effects passed multiple comparison correction (FDR q > .05). However, there were significant differences between male and female youth (FDR q < .05), with opposite relations between dependent stressor frequency and cortical GM thickness in the salience network and emotion regulation regions and with surface area in default mode network regions. These results motivate future investigations of gender differences in neural mechanisms of stress generation and reactivity. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Mechanism of Residual Stress Generation in Quenched Fe-Ni Alloy Cylinders Using Simulated Strains-Based Approach*

Abstract To elucidate the mechanisms of residual stress generation in quenched steel parts has been a longstanding problem. Qualitative explanations for the changes in the stress distribution in quenched cylinders appeared in the 1930s when it became possible to measure residual stresses in specimens. The explanation at that time used the concept of thermal and transformation stresses, which is still included in current textbooks. This concept is referred to here as the estimated stresses-based approach. To simplify the explanation of stress generation due to the combined effects of temperature change and phase transformations, quenching experiments were devised using Fe-Ni alloys in which only martensitic transformation occurs. On the other hand, since heat treatment simulations provide strains resulting from thermal, phase transformation, plastic, transformation plastic, and creep phenomena, a method to elucidate the mechanism using these strains was devised in the early 2000s and named the simulated strains-based approach. This paper contrasts the estimated stresses-based and simulated strains-based approaches to the mechanism of residual stress generation in quenched Fe-Ni alloy cylinders and highlights the superiority of the latter.

Stress generation in social anxiety and depression: A two-study community assessment

BackgroundStress generation theory suggests that people engage in certain behaviors that causally generate “dependent” stressful life events. Stress generation has primarily been studied in the context of depression with limited consideration of anxiety. People with social anxiety exhibit maladaptive social and regulatory behaviors that may uniquely generate stress. MethodAcross two studies, we examined if people with elevated social anxiety experienced more dependent stressful life events than those lower in social anxiety. On an exploratory basis, we examined differences in perceived intensity, chronicity, and self-blame of stressful life events. As a conservative test, we examined whether observed relationships held after covarying depression symptoms. Community adults (Ns = 303; 87) completed semi-structured interviews about recent stressful life events. ResultsParticipants with higher social anxiety symptoms (Study 1) and social anxiety disorder (SAD; Study 2) reported more dependent stressful life events than those with lower social anxiety. In Study 2, healthy controls rated dependent events as less impactful than independent events; those with SAD rated dependent and independent events as equally impactful. Regardless of social anxiety symptoms, participants placed greater blame on themselves for the occurrence of dependent than independent events. LimitationsLife events interviews are retrospective and preclude conclusions about short-term changes. Mechanisms of stress generation were not assessed. ConclusionsResults provide initial evidence for the role of stress generation in social anxiety that may be distinct from depression. Implications for assessing and treating unique and shared features of affective disorders are discussed.

3D Numerical modelling of residual stresses induced in finish turning of a fillet radius on a shaft made of 15-5PH

The objective of this paper is to model the residual stress generation mechanisms induced during the finish turning of a fillet radius on a 15-5PH steel shaft. The model, based on the 3D thermo-mechanical equivalent loading method, is used to predict the continuous variation of residual stresses resulting from the continuous variation of the machined sections in the fillet radius. Finally, experimental tests are carried out to compare the numerical results with the residual stress measurements made by X-ray diffraction in some positions.

Reliability Assessment of Thermocompressed Epoxy Molding Compound through Glass via Interposer Architecture by the Submodeling Simulation Approach.

In glass interposer architecture and its assembly process, the mechanical responses of interposer structure under thermocompression process-induced thermal loading and generated shrinkage of molding material are regarded as a major reliability issue. Thousands of metal-filled via are involved in glass interposers and are regarded as a potential risk that can lead to cracking and the failure of an entire vehicle. In this study, a finite element-based submodeling approach is demonstrated to overcome the complexity of modeling and the relevant convergence issue of interposer architecture. Convergence analysis results revealed that at least four via pitch-wide regions of a local simulation model were needed to obtain the stable results enabled by the submodeling simulation approach. The stress-generation mechanism during thermocompression, the coefficient of thermal expansion mismatch, and the curing process-induced shrinkage were separately investigated. The critical stress location was explored as the outer corner of the chip, and the maximum first principal stress during the thermocompression process generated on the chip and glass interposer were 34 and 120 MPa, respectively.

Modelling residual stress and residual work hardening induced by surface mechanical attrition treatment

Shot peening induced residual stress is strongly related to residual work hardening which relies on both the process and the target material. In this work, residual stress and coupled residual work hardening are studied in a surface mechanical attrition treatment (SMAT) on a cylindrical structure by combining discrete element method (DEM) and finite element method (FEM). Shot, ultrasonic parameters, chamber structure, sonotrode surface, and cylindrical structure of the target are finely modeled in DEM simulation. On the basis of the DEM results, FEM simulation of the SMAT process is performed on a representative area considering the factual impact parameters and elastic-plastic behavior of the target material, and mechanism of residual stress generation is analyzed. It shows that isotropic hardening and kinematic hardening of the target material play a different role in residual stress generation. The obtained maximum compressive residual stress is mainly determined by residual yield stress, while the residual kinematic hardening is nearly unchanged when the coverage is increased. Further analyses indicate that the mechanisms of residual stress generation should be very different for the Johnson-Cook model and the model that includes kinematic hardening, even though these two kinds of models are reported to be able to well predict the shot peening induced residual stress. The gradient of the residual work hardening can be used for further evaluating mechanical properties of the SMATed cylindrical structure.

Quenching Stress of Hot-Rolled Seamless Steel Tubes under Different Cooling Intensities Based on Simulation

Large residual stress occurs during the quenching process of hot-rolled seamless steel tubes, which results in bending, cracking, and ellipticity exceeding standards and seriously affects the quality of hot-rolled seamless steel tubes. In addition, the stress generation mechanism of hot-rolled seamless steel tubes is different from that of steel plates due to the characteristics of annular section. In this research, the finite element simulation method was used to study the quenching residual stress of seamless steel tubes with different cooling intensities. The variation law of temperature and stress on the steel tube under different cooling intensities were analyzed. The results show that the radial stress was close to 0, and the circumferential and axial stresses were the main factors affecting the quality of the steel tube. With the increase in the cooling time, the magnitude and direction of each stress component of the steel tube changed simultaneously. Finally, a typical stress distribution state of “external compressive stress, internal tensile stress” was presented in the thickness direction of the steel tube. Furthermore, with the increase in the cooling intensity, the residual stress of the steel tube gradually increased and was mainly concentrated on the near wall of the steel tube.

Subpicosecond Optical Stress Generation in Multiferroic BiFeO3.

Optical excitation leads to ultrafast stress generation in the prototypical multiferroic BiFeO3. The time scales of stress generation are set by the dynamics of the population of excited electronic states and the coupling of the electronic configuration to the structure. X-ray free-electron laser diffraction reveals high-wavevector subpicosecond-time scale stress generation following ultraviolet excitation of a BiFeO3 thin film. Stress generation includes a fast component with a 1/e rise time with an upper limit of 300 fs and longer-rise time components extending to 1.5 ps. The contributions of the fast and delayed components vary as a function of optical fluence, with a reduced a fast-component contribution at high fluence. The results provide insight into stress-generation mechanisms linked to the population of excited electrons and point to new directions in the application of nanoscale multiferroics and related ferroic complex oxides. The fast component of the stress indicates that structural parameters and properties of ferroelectric thin film materials can be optically modulated with 3 dB bandwidths of at least 0.5 THz.

Localized anisotropic stress in the sodiation of antimony anode

Although electrode degradation and failure in secondary batteries are hypothesized to stem from the localized chemo-electro-mechanical stress buildup during the charge-discharge process, the exact mechanism of stress generation is poorly understood. We quantitively resolve the stress accumulation in the Sb thin film anode during its gradual phase transitions in the sodiation/desodiation process by combining real-time electro-mechanical and electrochemical measurements with structural information further confirmed by spectroscopic methodologies. In the Sb thin films with (012) planes nearly normal to the surface, ~63% of the total interfacial stress (43.1 N m−1) is accumulated within the first 1/6 of the sodiation process of Na0.5Sb formation with Na-ions inserted between (012) planes. Only a small stress of 4.3 N m−1 is observed in the second 1/6 of the sodiation process due to preferential amorphization and solid solution formation. The last 2/3 of the sodiation process, where NaSb is converted into Na3Sb, generates only 1/3 of total stress (21.2 N m−1) because of the limited in-plane expansion. We also demonstrate that creating buffering voids can greatly reduce stress accumulation, especially during the early stage of the sodiation. The chemo-electro-mechanical insights from this work could serve as quantitative guidelines for the design and optimization of long-lasting Sb anode.

Investigating residual stress evolution in the deposition process of diamond-like carbon film through molecular dynamics

Diamond-like carbon (DLC) films possess excellent tribological properties, such as low friction and high wear resistance. However, DLC films detach easily owing to the high residual stress, which limits their application on mechanical sliding surfaces. To overcome this problem, it is crucial to clarify the residual stress generation mechanism in DLC films. In this study, molecular dynamics simulations were conducted on the deposition process of a DLC film to clarify the residual stress generation mechanism. The results suggest that sp3 hybridization clusters are nucleated in the sp2 formed on the film surface, and sp3 clusters grow in the sp2 carbon through the sp2 → sp3 bond change during the film growth process. The bond length of sp3 was approximately 8.5% larger than that of sp2 under stress-free bulk conditions. Thus, when the sp2 → sp3 bond change occurs under construction by surrounding atoms, compressive stress is generated in the sp3 cluster, which increases with the growth of the sp3 cluster. Based on the results, we conclude that the nucleation and growth of sp3 clusters in sp2 result in residual compressive stress in the DLC film. We believe that the present mechanism clarification of the stress development process in DLC films will facilitate the development of new methods for residual stress reduction.

Revealing the mechanism of stress generation for construction frontline professionals through development of structural stressors–coping–stress models

Construction industry is stressful for its participants. Construction frontline professionals are directly responsible for construction tasks on-site, and their stress management is of critical importance to the project success. Coping strategies could significantly affect stress, while the influence of various coping strategies on stressors–stress interactions for frontline professionals was unclear. Current study sets to examine the mediating effect of two groups of coping strategies on the relationships between stressors and stress. Over 500 valid quantitative data were applied to statistical analyses including confirmatory factor analysis and structural equation modeling (SEM). A final Stressors–Coping–Stress model was developed, which shows: 1) three problem-focused but only one emotion-focused coping strategies can mediate the stressors–stress interactions for frontline professionals; 2) three problem-focused copings, namely cognitive reappraisal, planful problem-solving and instrumental support, are promoted when they have job control, leading to reduced emotional stress; 3) planful problem-solving and instrumental support could mediate the influence of supervisor support on stress, but interestingly, mediating effect of instrumental support on supervisor support–stress interaction causes exacerbated physical stress; 4) the avoidance coping could be restrained by supervisor support but invoked by work overload, imposing different influence on their stress. Practical recommendations were made to improve stress management practices, including realistic workload planning, training for adaptive coping, provision of counselling services, etc. Through revealing the stressors–coping–stress interactions, this study contributed to enhance current understanding of stress management knowledge and improve existing strategies and practices regarding occupational health and safety in the construction industry.

Microscale residual stresses in additively manufactured stainless steel: Computational simulation

Metal additive manufacturing (AM) has attracted much attention in recent years due to its ability of producing parts with complex geometry. Unfortunately, the large temperature gradient during fabrication leads to residual stresses which undesirably result in distortion and even crack of as-built parts. A computational framework is used to study how residual stresses form and evolve in AM parts at the length scale of individual grains, including a multi-physics thermal-fluid flow model, a phase field model for grain growth and a crystal plasticity finite element model. First, this framework is validated by comparing the lattice strain with experimental results in different grain families in two samples made of 316L stainless steel, which were produced by laser powder-bed-fusion with two different sets of process parameters. The relationship between residual stress, plastic strain and grain orientation near the top surface of the samples is then investigated. The residual stresses are observed to form during laser scanning due to compression followed by tension around the molten pool, thus the shape of the molten pool has a significant influence on the residual stress distribution. Redistribution of the plastic deformation during cooling stage is predicted and the residual stresses with greater magnitude occur along the laser scanning direction. This work provides useful insight into the mechanism of microscale residual stress generation and evolution in AM parts.

A combined experimental and molecular simulation study on stress generation phenomena during the Ziegler-Natta polyethylene catalyst fragmentation process.

The morphology of particles obtained under different pre-polymerization conditions has been connected to the stress generation mechanism at the polymer/catalyst interface. A combination of experimental characterization techniques and atomistic molecular dynamics simulations allowed a systematic investigation of experimental conditions leading to a certain particle morphology, and hence to a final polymer with specific features. Atomistic models of nascent polymer phases in contact with magnesium dichloride surfaces have been developed and validated. Using these detailed models, in the framework of McKenna's hypothesis, the pressure increase due to the polymerization reaction has been calculated under different conditions and is in good agreement with experimental scenarios. This molecular scale knowledge and the proposed investigation strategy would allow the pre-polymerization conditions to be better defined and the properties of the nascent polymer to be tuned, ensuring proper operability along the whole polymer production process.