Biofeedback Stress Profile

2010 ◽  
Author(s):  
Richard Harvey
Keyword(s):  
Stress Profile

Validation of the Derogatis Stress Profile Using Laboratory and Real World Data

1991 ◽  
Vol 56 (4) ◽  
pp. 185-196 ◽  
Author(s):  
Patricia L. Dobkin ◽  
Robert O. Pihl ◽  
Claude Breault
Keyword(s):  
Real World ◽  
Stress Profile ◽  
Real World Data ◽  
World Data

Finite element modeling of residual stress profile patterns in hard turning

2009 ◽  
Vol 24 (S1) ◽  
pp. S22-S25
Author(s):  
Y. B. Guo ◽  
S. Anurag
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Finite Element Modeling ◽  
Hard Turning ◽  
Internal State ◽  
Stress Profile ◽  
Surface Residual Stress ◽  
Mechanical Coupling ◽  
Element Modeling ◽  
Stress Profiles

Hard turning, i.e., turning hardened steels, may produce the unique “hook” shaped residual stress (RS) profile characterized by surface compressive RS and subsurface maximum compressive RS. However, the formation mechanism of the unique RS profile is not yet known. In this study, a novel hybrid finite element modeling approach based on thermal-mechanical coupling and internal state variable plasticity model has been developed to predict the unique RS profile patterns by hard turning AISI 52100 steel (62 HRc). The most important controlling factor for the unique characteristics of residual stress profiles has been identified. The transition of maximum residual stress at the surface to the subsurface has been recovered by controlling the plowed depth. The predicted characteristics of residual stress profiles favorably agree with the measured ones. In addition, friction coefficient only affects the magnitude of surface residual stress but not the basic shape of residual stress profiles.

scholarly journals Structural Equation Modeling of a Global Stress Index in Healthy Soldiers

2021 ◽  
Vol 10 (8) ◽  
pp. 1799
Author(s):  
Tanja Maier ◽  
Melanie Kugelmann ◽  
Dae-Sup Rhee ◽  
Sebastian Brill ◽  
Harald Gündel ◽  
...  
Keyword(s):  
Structural Equation Modeling ◽  
Cardiovascular Risk ◽  
Chronic Stress ◽  
Structural Equation ◽  
Hierarchical Level ◽  
Stress Index ◽  
Equation Modeling ◽  
Stress Profile ◽  
Acute And Chronic Stress ◽  
Global Stress

Accumulation of stress is a prognostic trigger for cardiovascular disease. Classical scores for cardiovascular risk estimation typically do not consider psychosocial stress. The aim of this study was to develop a global stress index (GSI) from healthy participants by combining individual measures of acute and chronic stress from childhood to adult life. One-hundred and ninety-two female and male soldiers completed the Perceived Stress Scale (PSS4), Trier Inventory for Chronic Stress (TICS), Hospital Anxiety and Depression Scale (HADS), Childhood Trauma Questionnaire (CTQ), Posttraumatic Diagnostic Scale Checklist (PDS), and the Deployment Risk and Resilience Inventory (DRRI-2). The underlying structure for the GSI was examined through structural equation modeling. The final hierarchical multilevel model revealed fair fit by taking modification indices into account. The highest order had a g-factor called the GSI. On a second level the latent variables stress, HADS and CTQ were directly loading on the GSI. A third level with the six CTQ subscales was implemented. On the lowest hierarchical level all manifest variables and the DRRI-2/PDS sum scores were located. The presented GSI serves as a valuable and individual stress profile for soldiers and could potentially complement classical cardiovascular risk factors.

Surface Modification Analysis after Shot Peening of AA 7075 in Different States

2013 ◽  
Vol 768-769 ◽  
pp. 519-525 ◽  
Author(s):  
Sebastjan Žagar ◽  
Janez Grum
Keyword(s):  
Residual Stress ◽  
Surface Layer ◽  
Residual Stresses ◽  
Aluminium Alloy ◽  
Shot Peening ◽  
Fatigue Testing ◽  
Stress Profile ◽  
Treatment Conditions ◽  
Stress Profiles ◽  
Compressive Residual Stresses

The paper deals with the effect of different shot peening (SP) treatment conditions on the ENAW 7075-T651 aluminium alloy. Suitable residual stress profile increases the applicability and life cycle of mechanical parts, treated by shot peening. The objective of the research was to establish the optimal parameters of the shot peening treatment of the aluminium alloy in different precipitation hardened states with regard to residual stress profiles in dynamic loading. Main deformations and main residual stresses were calculated on the basis of electrical resistance. The resulting residual stress profiles reveal that stresses throughout the thin surface layer of all shot peened specimens are of compressive nature. The differences can be observed in the depth of shot peening and the profile of compressive residual stresses. Under all treatment conditions, the obtained maximum value of compressive residual stress ranges between -200 MPa and -300 MPa at a depth between 250 μm and 300 μm. Comparison of different temperature-hardened aluminium alloys shows that changes in the Almen intensity values have greater effect than coverage in the depth and profile of compressive residual stresses. Positive stress ratio of R=0.1 was selected. Wöhler curves were determined in the areas of maximum bending loads between 30 - 65 % of material's tensile strength, measured at thinner cross-sections of individual specimens. The results of material fatigue testing differ from the level of shot peening on the surface layer.

Evaluation of Blister Behavior for U10Mo Mini Fuel Plates With Cold Rolled Foils

2012 ◽  
Author(s):  
Hakan Ozaltun ◽  
Samuel J. Miller
Keyword(s):  
Cold Rolling ◽  
Thermal Cycling ◽  
Cold Work ◽  
Rolling Process ◽  
Foil Thickness ◽  
Rolled Plate ◽  
Stress Profile ◽  
Wide Range ◽  
Threshold Temperatures ◽  
Cold Rolled

This article aims to provide possible mechanical causes for the lowered blister temperatures of RERTR-12 and AFIP-4 fuel plates. Recent experimental investigations to determine the blister threshold temperatures have indicated lower thresholds for similar plates with comparable burn-up histories. Measured blister temperatures of roughly 100 °C lower compared to the previously tested plates may not be satisfactory for some plates. The primary differences between recent experiments and previous tests are: (1) An aggressive cold work process involving large thickness reduction ratios without normalization or full annealing (2) Subjecting the plates to a thermal cycling process prior to irradiation, and finally (3) A primarily frontal neutron flux as opposed to a transverse flux profile. It is believed that the stress field has implications to blister behavior. To investigate this claim, the stress-strain states for the fabrication procedure were evaluated. First, the residual stress profile caused by the cold rolling process was calculated. Modeling of the cold rolling process has shown confirmation of residual stresses of considerable magnitude and the existence of stress gradients with respect to foil thickness prior to the HIP process. Once calculated, these stress profiles were used as an initial condition for the fabrication process. Due to the variation in stress fields depending on location at which a foil is cut from the cold rolled plate, three representative regions were selected and implemented in the HIP simulation. Variation in stresses, depending on location of the cold rolled plate as well and variation in the through-thickness, results in a wide range of mechanical stress states. This suggests that inhomogeneous irradiation and thermal cycling behavior will result from the use of cold rolled foils. Additionally, these results suggest that there will be fundamental differences in fuel plate behavior observed between plates fabricated with cold rolled foils versus hot rolled and fully annealed foils.

The biomechanical effects of S-type dynamic cage using Ti and PEEK for ACDF surgery on cervical spine varying loads

2021 ◽  
pp. 039139882110395
Author(s):  
Pechimuthu Susai Manickam ◽  
Sandipan Roy
Keyword(s):  
Disc Degeneration ◽  
Lower Risk ◽  
Mechanical Stability ◽  
Early Stage ◽  
Cervical Disc ◽  
Adjacent Segment ◽  
Stress Profile ◽  
Fe Model ◽  
Cage Subsidence ◽  
Adjacent Disc

Anterior cervical discectomy with fusion (ACDF) is the common method to treat the cervical disc degeneration. The most serious problems in the fusion cages are adjacent disc degeneration, loss of lordosis, pain, subsidence, and migration of the cage. The objective of our work is to develop the three-dimensional finite element (FE) model from C3-C6 and virtually implant a designed S-type dynamic cage at C4-C5 segment of the model. The dynamic cage design will provide mobility in the early stage after ACDF surgery. Titanium (Ti) and PEEK (polyether ether ketone) were used as the material property for the cages. We applied the physiological motions at different loads from 0.5, 1, 1.5, 2.0 Nm to evaluate the dynamic cage design and the biomechanical performances of the designed S-type dynamic cage. It was observed that in all the loading condition the range of motion in the adjacent level was maintained and the maximum stress at the adjacent disc was reduced. The clinical significance of the S-type dynamic cage is better stress profile at the fusion level and adjacent segments which translates into higher rate of fusion, lower risk of cage subsidence, lower risk of adjacent segment degeneration, and good mechanical stability.

NUMERICAL SOLUTION OF TWO-DIMENSIONAL PROBLEMS OF THERMOVISCOELASTICITY

2021 ◽  
Vol 335 (1) ◽  
pp. 60-64
Author(s):  
M. Bukenov ◽  
Ye. Mukhametov
Keyword(s):  
A Priori ◽  
Elastic Collision ◽  
Qualitative Behavior ◽  
Stress Profile ◽  
Two Dimensional ◽  
A Priori Information ◽  
Deformable Solids ◽  
Methods Of Calculation ◽  
The Difference ◽  
Priori Information

This paper considers the numerical implementation of two-dimensional thermoviscoelastic waves. The elastic collision of an aluminum cylinder with a two-layer plate of aluminum and iron is considered. In work [1] the difference schemes and algorithm of their realization are given. The most complete reviews of the main methods of calculation of transients in deformable solids can be found in [2, 3, 4], which also indicates the need and importance of generalized studies on the comparative evaluation of different methods and identification of the areas of their most rational application. In the analysis and physical interpretation of numerical results in this work it is also useful to use a priori information about the qualitative behavior of the solution and all kinds of information about the physics of the phenomena under study. Here is the stage of evolution of contact resistance of collision – plate, stress profile.

Controlled Frac Height Growth Technique to Avoid Contacting Water-Bearing Layer

2022 ◽  
Author(s):  
Hashem Al-Obaid ◽  
Sultan A. Asel ◽  
Jon Hansen ◽  
Rio Wijaya
Keyword(s):  
Hydraulic Fracturing ◽  
Height Growth ◽  
Gas Production ◽  
Stress Profile ◽  
Water Production ◽  
Tight Sandstone ◽  
Water Contact ◽  
Vertical Fracture ◽  
Vertical Growth ◽  
Water Zone

Abstract Many techniques have been used to model, diagnose and detect fracture dimension and propagation during hydraulic fracturing. Diagnosing fracture dimension growth vs time is of paramount importance to reach the desired geometry to maximize hydrocarbon production potential and prevent contacting undesired fluid zones. The study presented here describes a technique implemented to control vertical fracture growth in a tight sandstone formation being stimulated near a water zone. This gas well was completed vertically as openhole with Multi- Stage Fracturing (MSF). Pre-Fracturing diagnostic tests in combination with high-resolution temperature logs provided evidence of vertical fracture height growth downward toward water zone. Pre-fracturing flowback indicated water presence that was confirmed by lab test. Several actions were taken to mitigate fracture vertical growth during the placement of main treatment. An artificial barrier with proppant was placed in the lower zone of the reservoir before main fracturing execution. The rate and viscosity of fracturing fluids were also adjusted to control the net pressure aiming to enhance fracture length into the reservoir. The redesigned proppant fracturing job was placed into the formation as planned. Production results showed the effectiveness of the artificial lower barrier placed to prevent fracture vertical growth down into the water zone. Noise log consists of Sonic Noise Log (SNL) and High Precision Temperature (HPT) was performed. The log analysis indicated that two major fractures were initiated away from water-bearing zone with minimum water production. Additionally, in- situ minimum stress profile indicated no enough contrast between layers to help confine fracture into the targeted reservoir. Commercial gas production was achieved after applying this stimulation technique while keeping water production rate controlled within the desired range. The approach described in this paper to optimize gas production in tight formation with nearby water contact during hydraulic fracturing treatments has been applied with a significant improvement in well production. This will serve as reference for future intervention under same challenging completion conditions.

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