The Method of Accounting for Loading Cycle Asymmetry in Cyclic Durability Analysis

2009 ◽  
Author(s):  
R. H. Muratov ◽  
M. A. Kornilova
Keyword(s):  
Strain Range ◽  
Cyclic Strain ◽  
Average Stress ◽  
Stress And Strain ◽  
Transient Strain ◽  
Asymmetric Loading ◽  
High Durability ◽  
Durability Analysis ◽  
Cyclic Durability ◽  
The Impact

The proposed method has been demonstrated on the universal slopes equation (Manson 1965) and the modified universal slopes equation (Muralidharan & Manson 1998). New equations take into account independence of the transient strain range from the cycle average stress, define more precisely the impact of the cycle average stress upon the durability, take into account the impact of cycle average strain plastic constituent upon the durability. The resulted equations have been validated with finite element analyses of non-notched samples and full-scale parts, for which the results of cyclic tests in the conditions of asymmetric loading are available. The analyses have been performed employing an elastic-plastic approach using cyclic strain curves taken from original durability equations. The use of new equations ensured a good match between design and experimental durability values. Also, the new equations were used to plot Smith, Hay and Wo¨hler diagrams for low, mean and high durability. The resulted analytical diagrams represent a high quality illustration of the experimental diagrams found in the publications. The presented approach to the accounting for cycle average stress and strain will also apply when using experimental cyclic durability curves specific for the material.

The Method of Accounting for Loading Cycle Asymmetry in Gas Turbine Engine Components’ Cyclic Durability Analysis

2006 ◽  
Author(s):  
R. H. Muratov
Keyword(s):  
Strain Range ◽  
Cyclic Strain ◽  
Mean Stress ◽  
Turbine Engine ◽  
Transient Strain ◽  
High Durability ◽  
Durability Analysis ◽  
Cyclic Durability ◽  
Engine Components ◽  
The Impact

The proposed method has been demonstrated on the universal slopes equation (Manson 1965) and the modified universal slopes equation (Muralidharan & Manson 1998). New equations take into account independence of the transient strain range from the cycle mean stress, define more precisely the impact of the cycle mean stress upon the durability, take into account the impact of cycle mean strain plastic component upon the durability. The resulted equations have been validated with finite element analyses of smooth samples and full-scale parts, for which the results of cyclic tests in the conditions of asymmetric loading are available. The analyses have been performed employing an elastic-plastic approach using cyclic strain curves taken from original durability equations. The use of new equations ensured a good match between design and experimental durability values. Also, the new equations were used to plot Smith and Hay diagrams for low, mean and high durability. The resulted analytical diagrams represent a high quality illustration of the experimental diagrams found in the publications. The presented approach to the accounting for cycle mean stress and strain will also apply when using experimental cyclic durability curves specific for the material.

scholarly journals Predicting the behavior of reinforced concrete columns confined by fiber reinforced polymers using data mining techniques

2021 ◽  
Vol 3 (2) ◽  
Author(s):  
Sahar Y. Ghanem ◽  
Heba Elgazzar
Keyword(s):  
Compressive Strength ◽  
Reinforced Concrete ◽  
Compressive Stress ◽  
Compressive Strain ◽  
Concrete Columns ◽  
Steel Reinforcement ◽  
Fiber Reinforced Polymers ◽  
Stress And Strain ◽  
Fiber Reinforced ◽  
The Impact

AbstractFiber Reinforced Polymer (FRP) usage to wrap reinforced concrete (RC) structures has become a popular technology. Most studies about RC columns wrapped with FRP in literature ignored the internal steel reinforcement. This paper aims to develop a model for the axial compressive strength and axial strain for FRP confined concrete columns with internal steel reinforcement. The impact of FRP, Transverse, and longitudinal reinforcement is studied. Two non-destructive analysis methods are explored: Artificial Neural Networks (ANNs) and Regression Analysis (RA). The database used in the analysis contains the experimental results of sixty-four concrete columns under the compressive concentric load available in the literature. The results show that both models can predict the column's compressive stress and strain reasonably with low error and high accuracy. FRP has the highest effect on the confined compressive stress and strain compared to other materials. While the longitudinal steel actively contributes to the compressive strength, and the transverse steel actively contributes to the compressive strain.

Stereoscopically Observed Deformations of a Compliant Abdominal Aortic Aneurysm Model

2011 ◽  
Vol 133 (11) ◽  
Author(s):  
Clark A. Meyer ◽  
Eric Bertrand ◽  
Olivier Boiron ◽  
Valérie Deplano
Keyword(s):  
Abdominal Aortic Aneurysm ◽  
Aortic Aneurysm ◽  
Computational Models ◽  
Imaging System ◽  
Strain Differences ◽  
Cyclic Strain ◽  
Experimental Models ◽  
Body Motion ◽  
Abdominal Aortic ◽  
The Impact

A new experimental setup has been implemented to precisely measure the deformations of an entire model abdominal aortic aneurysm (AAA). This setup addresses a gap between the computational and experimental models of AAA that have aimed at improving the limited understanding of aneurysm development and rupture. The experimental validation of the deformations from computational approaches has been limited by a lack of consideration of the large and varied deformations that AAAs undergo in response to physiologic flow and pressure. To address the issue of experimentally validating these calculated deformations, a stereoscopic imaging system utilizing two cameras was constructed to measure model aneurysm displacement in response to pressurization. The three model shapes, consisting of a healthy aorta, an AAA with bifurcation, and an AAA without bifurcation, were also evaluated with computational solid mechanical modeling using finite elements to assess the impact of differences between material properties and for comparison against the experimental inflations. The device demonstrated adequate accuracy (surface points were located to within 0.07 mm) for capturing local variation while allowing the full length of the aneurysm sac to be observed at once. The experimental model AAA demonstrated realistic aneurysm behavior by having cyclic strains consistent with reported clinical observations between pressures 80 and 120 mm Hg. These strains are 1–2%, and the local spatial variations in experimental strain were less than predicted by the computational models. The three different models demonstrated that the asymmetric bifurcation creates displacement differences but not cyclic strain differences within the aneurysm sac. The technique and device captured regional variations of strain that are unobservable with diameter measures alone. It also allowed the calculation of local strain and removed rigid body motion effects on the strain calculation. The results of the computations show that an asymmetric aortic bifurcation created displacement differences but not cyclic strain differences within the aneurysm sac.

scholarly journals Influence of Orthotropy on Biomechanics of Peri-Implant Bone in Complete Mandible Model with Full Dentition

2014 ◽  
Vol 2014 ◽  
pp. 1-12 ◽  
Author(s):  
Xi Ding ◽  
Sheng-Hui Liao ◽  
Xing-Hao Zhu ◽  
Hui-Ming Wang
Keyword(s):  
Orthotropic Material ◽  
Tooth Enamel ◽  
Local Stress ◽  
Isotropic Case ◽  
Stress And Strain ◽  
Isotropic Model ◽  
Bone Interface ◽  
Multiple Data ◽  
Cad Models ◽  
The Impact

Objective.The study was to investigate the impact of orthotropic material on the biomechanics of dental implant, based on a detailed mandible with high geometric and mechanical similarity.Materials and Methods.Multiple data sources were used to elaborate detailed biological structures and implant CAD models. In addition, an extended orthotropic material assignment methodology based on harmonic fields was used to handle the alveolar ridge region to generate compatible orthotropic fields. The influence of orthotropic material was compared with the commonly used isotropic model and simplified orthotropic model.Results.The simulation results showed that the values of stress and strain on the implant-bone interface almost increased in the orthotropic model compared to the isotropic case, especially for the cancellous bone. However, the local stress concentration was more obvious in the isotropic case compared to that in orthotropic case. The simple orthotropic model revealed irregular stress and strain distribution, compared to the isotropic model and the real orthotropic model. The influence of orthotropy was little on the implant, periodontal ligament, tooth enamel, and dentin.Conclusion.The orthotropic material has significant effect on stress and strain of implant-bone interface in the mandible, compared with the isotropic simulation. Real orthotropic mechanical properties of mandible should be emphasized in biomechanical studies of dental implants.

The Propagation of Plasticity in Uniaxial Compression

1948 ◽  
Vol 15 (3) ◽  
pp. 256-260 ◽  
Author(s):  
M. P. White ◽  
LeVan Griffis
Keyword(s):  
Uniaxial Compression ◽  
Thin Sheet ◽  
High Stress ◽  
Stress And Strain ◽  
Velocity Range ◽  
Plastic Materials ◽  
The Face ◽  
Elastic Plastic Materials ◽  
The Impact ◽  
Type Of Behavior

Abstract A theoretical investigation of the mechanism of uniaxial compression impact on elastic-plastic materials is described in this paper. The method of analysis is similar in some respects to that previously given for tension impact on such materials. It is concluded that four different kinds of behavior can occur, depending upon the impact velocity. In the lowest velocity range the behavior in compression is similar to that found in tension. In this case stress and strain are propagated from the point of impact as a zone or wave front of ever-increasing length. This type of behavior ends at a velocity corresponding to the “critical” velocity found in tension impact. Within the next higher velocity range, stress and strain are propagated as a shock-type wave, or wave of very small length in which the transition from low to high stress and strain is very abrupt. At still higher impact velocities, there occurs “flowing deformation” in which the material is too weak to maintain coherency. Here there is a steady flow of the material toward and against the hammer, after which it flows in a thin sheet radially outward over the face of the hammer. The final possible state occurs at impact velocities greater than the speed of an elastic wave, so that no disturbance can escape from the hammer into the medium. Here the behavior is essentially that of a fluid, impact force being independent of strength of material.

scholarly journals Evidence for the Desmosomal Cadherin Desmoglein-3 in Regulating YAP and Phospho-YAP in Keratinocyte Responses to Mechanical Forces

2019 ◽  
Vol 20 (24) ◽  
pp. 6221 ◽  
Author(s):  
Jutamas Uttagomol ◽  
Usama Sharif Ahmad ◽  
Ambreen Rehman ◽  
Yunying Huang ◽  
Ana C. Laly ◽  
...  
Keyword(s):  
Target Genes ◽  
Hippo Pathway ◽  
Cyclic Strain ◽  
Cell Periphery ◽  
Mechanical Forces ◽  
Force Transmission ◽  
Direct Role ◽  
The Impact ◽  
Desmoglein 3 ◽  
E Cadherin

Desmoglein 3 (Dsg3) plays a crucial role in cell-cell adhesion and tissue integrity. Increasing evidence suggests that Dsg3 acts as a regulator of cellular mechanotransduction, but little is known about its direct role in mechanical force transmission. The present study investigated the impact of cyclic strain and substrate stiffness on Dsg3 expression and its role in mechanotransduction in keratinocytes. A direct comparison was made with E-cadherin, a well-characterized mechanosensor. Exposure of oral and skin keratinocytes to equiaxial cyclic strain promoted changes in the expression and localization of junction assembly proteins. The knockdown of Dsg3 by siRNA blocked strain-induced junctional remodeling of E-cadherin and Myosin IIa. Importantly, the study demonstrated that Dsg3 regulates the expression and localization of yes-associated protein (YAP), a mechanosensory, and an effector of the Hippo pathway. Furthermore, we showed that Dsg3 formed a complex with phospho-YAP and sequestered it to the plasma membrane, while Dsg3 depletion had an impact on both YAP and phospho-YAP in their response to mechanical forces, increasing the sensitivity of keratinocytes to the strain or substrate rigidity-induced nuclear relocation of YAP and phospho-YAP. Plakophilin 1 (PKP1) seemed to be crucial in recruiting the complex containing Dsg3/phospho-YAP to the cell surface since its silencing affected Dsg3 junctional assembly with concomitant loss of phospho-YAP at the cell periphery. Finally, we demonstrated that this Dsg3/YAP pathway has an influence on the expression of YAP1 target genes and cell proliferation. Together, these findings provide evidence of a novel role for Dsg3 in keratinocyte mechanotransduction.

Stress in Social Workers: The Impact of Setting and Role

1986 ◽  
Vol 67 (3) ◽  
pp. 141-148 ◽  
Author(s):  
William C. Sze ◽  
Barry Ivker
Keyword(s):  
Social Workers ◽  
Work Role ◽  
Stress And Strain ◽  
Work Setting ◽  
The Impact

A study of the impact of work setting and role on stress and strain in social workers showed that approximately 60 percent of respondents had experienced increased stress in the last two years. Levels of stress, measured by increases in stress-related symptoms, seemed to be associated with both work setting and work role.

Fatigue Properties of Superelastic Ti-Ni Filaments Used in Braided Cables for Bone Fixation

2008 ◽  
Vol 57 ◽  
pp. 235-240 ◽  
Author(s):  
Yannick Baril ◽  
Vladimir Brailovski ◽  
Patrick Terriault
Keyword(s):  
Fatigue Life ◽  
Strain Range ◽  
Fatigue Properties ◽  
Cyclic Testing ◽  
Testing Conditions ◽  
Bone Fixation ◽  
Ni Alloys ◽  
Strain Magnitude ◽  
The Impact ◽  
Mean Strain

Superelastic 0.1mm diameter Ti-Ni filaments are used to manufacture braided orthopedic cable for bone fixation. Biomechanical conditions for this application generally have a cyclic nature, and therefore it becomes important to evaluate the influence of the installation (mean) strain on the fatigue life of these filaments. Uniaxial tension cyclic testing of Ti-Ni filaments is performed in a water bath at 37°C with a 2Hz frequency of to 100 000 cycles. Strain-controlled testing conditions are as follows: alternating strain magnitude varies between 0.64 and 3.64% with mean strain range between 1.32 and 7.1%. Based on the premises that the minimum strain should be high enough to prevent any loss of tension in the tested specimen and that the maximum strain should not bring the specimen to failure during the first loading cycle, the total strain magnitude is encompassed between 0.68 and 8.94%. The results obtained provide a better understanding of the impact mean strain has on the fatigue life of superelastic Ti-Ni alloys.

Axial Impact Performance of Aluminium Thin Cylindrical Tube

2013 ◽  
Vol 315 ◽  
pp. 1-5 ◽  
Author(s):  
Perowansa Paruka ◽  
Waluyo Adi Siswanto
Keyword(s):  
Finite Element ◽  
High Speed ◽  
Cylindrical Tube ◽  
Numerical Approach ◽  
Stress And Strain ◽  
Axial Impact ◽  
Cylindrical Structure ◽  
Impact Performance ◽  
Impact Simulation ◽  
The Impact

One of the important objectives in this research is investigating the behavior on the cylindrical tube structure via computer simulations. When a thin cylindrical structure is experienced an impact loading, the crushing process on impact can only be observed by a high speed camera. Recording the stress and strain data is also not possible experimentally. A numerical approach implementing finite element method with a dynamic-explicit code is an effective solution to observe the crushing process. A thin cylindrical structure found in aluminium can is modeled. A finite element impact simulation is then performed to observe the crushing process sequence and the stress and strain development history on axial impact employing IMPACT application program. An experimental of thin cylindrical structure on axial impact is conducted. The final crushing pattern after the impact is then compared with that from simulation. The result shows that final crushing pattern is in a good agreement with that shown in experiment. The stress and strain histories can be observed from the simulation.

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