Research on the Stress and Strain Field and Wall Thickness in Power Spinning of Ellipsoidal Heads with Variable Thickness

2011 ◽  
Vol 189-193 ◽  
pp. 1960-1963 ◽  
Author(s):  
Jin Hui Zhang ◽  
He Yang ◽  
Mei Zhan ◽  
Hua Bing Jiang
Keyword(s):  
Contact Zone ◽  
Wall Thickness ◽  
Variable Thickness ◽  
Large Strain ◽  
Stress And Strain ◽  
Fe Model ◽  
Stress Strain ◽  
Power Spinning ◽  
In The Beginning ◽  
Distribution Of Stress

In this paper, a reasonable 3D FE model for power spinning of ellipsoidal heads with variable thickness has been established under ABAQUS/Explicit and validated. Then the variation of stress, strain and wall thickness during the process are obtained. Furthermore, the influence of the springback on stress, strain and wall thickness are gained with ABAQUS/Standard. The results show the following: (1) In the beginning, large stress, large strain and the thinning zone of wall thickness localize at the small contact zone below the roller; Then the zone extends into a ring and moves towards the position behind the roller; In the end, the ring transfers to the contact zone below the roller again and becomes uneven. The thinning zone is gradually impelled along the generatrix direction, and wall thickness is getting smaller and smaller. (2) The distribution of stress becomes more even after the springback, while the springback has little effect on the distribution of strain and wall thickness.

scholarly journals Infarcted Left Ventricles Have Stiffer Material Properties and Lower Stiffness Variation: Three-Dimensional Echo-Based Modeling to Quantify In Vivo Ventricle Material Properties

2015 ◽  
Vol 137 (8) ◽  
Author(s):  
Longling Fan ◽  
Jing Yao ◽  
Chun Yang ◽  
Dalin Tang ◽  
Di Xu
Keyword(s):  
Wall Thickness ◽  
Material Properties ◽  
Strain Curve ◽  
Stress And Strain ◽  
Stress Strain ◽  
Material Stiffness ◽  
The Mean ◽  
Lv Volume ◽  
Parameter Values

Methods to quantify ventricle material properties noninvasively using in vivo data are of great important in clinical applications. An ultrasound echo-based computational modeling approach was proposed to quantify left ventricle (LV) material properties, curvature, and stress/strain conditions and find differences between normal LV and LV with infarct. Echo image data were acquired from five patients with myocardial infarction (I-Group) and five healthy volunteers as control (H-Group). Finite element models were constructed to obtain ventricle stress and strain conditions. Material stiffening and softening were used to model ventricle active contraction and relaxation. Systolic and diastolic material parameter values were obtained by adjusting the models to match echo volume data. Young's modulus (YM) value was obtained for each material stress–strain curve for easy comparison. LV wall thickness, circumferential and longitudinal curvatures (C- and L-curvature), material parameter values, and stress/strain values were recorded for analysis. Using the mean value of H-Group as the base value, at end-diastole, I-Group mean YM value for the fiber direction stress–strain curve was 54% stiffer than that of H-Group (136.24 kPa versus 88.68 kPa). At end-systole, the mean YM values from the two groups were similar (175.84 kPa versus 200.2 kPa). More interestingly, H-Group end-systole mean YM was 126% higher that its end-diastole value, while I-Group end-systole mean YM was only 29% higher that its end-diastole value. This indicated that H-Group had much greater systole–diastole material stiffness variations. At beginning-of-ejection (BE), LV ejection fraction (LVEF) showed positive correlation with C-curvature, stress, and strain, and negative correlation with LV volume, respectively. At beginning-of-filling (BF), LVEF showed positive correlation with C-curvature and strain, but negative correlation with stress and LV volume, respectively. Using averaged values of two groups at BE, I-Group stress, strain, and wall thickness were 32%, 29%, and 18% lower (thinner), respectively, compared to those of H-Group. L-curvature from I-Group was 61% higher than that from H-Group. Difference in C-curvature between the two groups was not statistically significant. Our results indicated that our modeling approach has the potential to determine in vivo ventricle material properties, which in turn could lead to methods to infer presence of infarct from LV contractibility and material stiffness variations. Quantitative differences in LV volume, curvatures, stress, strain, and wall thickness between the two groups were provided.

scholarly journals STRESS‐STRAIN ANALYSIS IN THE SOIL SAMPLE DURING LABORATORY TESTING

2007 ◽  
Vol 13 (1) ◽  
pp. 63-70 ◽  
Author(s):  
Neringa Verveckaite ◽  
Jonas Amsiejus ◽  
Vincentas Stragys
Keyword(s):  
Cross Section ◽  
Strain Analysis ◽  
Soil Strength ◽  
Horizontal Component ◽  
Stress And Strain ◽  
Stress Strain ◽  
Real Distribution ◽  
The Cross ◽  
Shear Box ◽  
Distribution Of Stress

During the determination of soil strength and compressibility in a laboratory by different apparatus soil is loaded in a different way. It has an influence on stress‐strain distribution in a sample. Some factors are not evaluated during the results interpretation, for example, friction between soil and device metal parts. The finite‐element method analysis also shows that during triaxial, oedometer, shear box tests distribution of stress and strain in the sample is non‐uniform. A special apparatus was designed and used for determining horizontal component of stress in the cross‐section of the sample. It was determined for sands that horizontal component of stress in the cross‐section centre is significantly smaller than at the edges. Increasing load plastic deformations are developing not in the whole sample but in particular places. If we know a real distribution of stress and strain in the sample, it is possible to determine the soil strength and deformation parameters in a more precise way or to rate the influence of different factors on soil properties.

Note on Stress and Strain Redistribution in a Notched Plate Specimen During Cyclic Loading

1969 ◽  
Vol 91 (3) ◽  
pp. 379-382 ◽  
Author(s):  
D. F. Mowbray ◽  
T. Slot
Keyword(s):  
Strain Softening ◽  
Cyclic Strain ◽  
Cyclic Stress ◽  
Computational Method ◽  
Stress And Strain ◽  
Stress Strain ◽  
Fatigue Specimen ◽  
Plate Specimen ◽  
Measured Strain ◽  
Distribution Of Stress

A finite-element computational method is employed to determine the spatial distribution of stress and strain in a notched-plate fatigue specimen fabricated of mild steel. Because of cyclic strain softening of the material, there is a redistribution of stress and strain in the specimen as a function of the number of load cycles. This phenomenon is considered in the analysis by using cyclic stress-strain diagrams as effective stress-strain curves. The numerical results are found to correlate well with measured strain distributions reported in the literature.

Research on Variation of Stress and Strain Field and Wall Thickness during Cone Spinning

2006 ◽  
Vol 532-533 ◽  
pp. 149-152 ◽  
Author(s):  
Mei Zhan ◽  
He Yang ◽  
Jin Hui Zhang ◽  
Yin Li Xu ◽  
Fei Ma
Keyword(s):  
Wall Thickness ◽  
Large Strain ◽  
Metal Flow ◽  
Small Region ◽  
Small Ring ◽  
Forming Process ◽  
Optimization Of Process Parameters ◽  
Spinning Process ◽  
Metal Forming Process ◽  
In The Beginning

Cone spinning is an advanced but complex metal forming process under coupled effects of multi-factors. Understanding the deformation mechanism, i.e., the stresses, strains, and metal flow in the deformation zone during the process is of great significance for optimizing the spinning process and controlling the product quality. In this paper, based on ABAQUS/Explicit, a reasonable FEM model for cone spinning with a single roller has been established, and the features of stress, strain and wall thickness during the process have been obtained. The results show the following: (1) In the beginning, large stress, large strain and the acute thinning of wall thickness localize at the small region below the roller, then the region extends into a small ring, further it becomes a large ring, and finally the ring will become uneven if the wrinkling occurs in the flange. (2) After spinning, the acute thinning region locates at the midst of the wall near the bottom of the workpiece. (3) At earlier stage of cone spinning, as a result of the acute thinning of wall thickness in the wall zone, the unevenness of wall thickness increases sharply to a value, then it almost keeps the value at the stable stage, and finally it will slowly increase again if the wrinkling appears in the flange. The results are helpful for determination and optimization of process parameters of cone spinning.

Numerical Analysis of Tension Force Subjected by Flexible Mattress

2015 ◽  
Vol 740 ◽  
pp. 116-119
Author(s):  
Zhen Yu Li ◽  
Ping Yang ◽  
Zhi Hua Sun ◽  
Lin Suan Liu
Keyword(s):  
Numerical Analysis ◽  
Large Strain ◽  
Fem Analysis ◽  
Tension Force ◽  
Stress And Strain ◽  
Nonlinear Fem ◽  
Fem Model ◽  
In Situ Test ◽  
Distribution Of Stress

The nonlinear FEM analysis is performed to the problem of large strain nonlinear application for flexible mattress. The element with cloth type option is used to establish the FEM model for the analysis of flexible mattress. The simulation can produce correct profile of deformation, accurate distribution of stress and strain, meanwhile taking account of geometric nonlinear from large strain. The results of the paper are compared with those from the theory and in-situ test. Some valuable conclusions are made from the results analysis.

scholarly journals Numerical Analysis of the Perforated Steel Sheets Under Uni-Axial Tensile Force

Metals ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 632 ◽  
Author(s):  
Ahmed M. Sayed
Keyword(s):  
Load Capacity ◽  
Tensile Force ◽  
Three Dimensional ◽  
Tensile Load ◽  
Experimental Tests ◽  
Strain Engineering ◽  
Uniaxial Tensile ◽  
Fe Model ◽  
Stress Strain ◽  
Steel Sheets

The perforated steel sheets have many uses, so they should be studied under the influence of the uniaxial tensile load. The presence of these holes in the steel sheets certainly affects the mechanical properties. This paper aims at studying the behavior of the stress-strain engineering relationships of the perforated steel sheets. To achieve this, the three-dimensional finite element (FE) model is mainly designed to investigate the effect of this condition. Experimental tests were carried out on solid specimens to be used in the test of model accuracy of the FE simulation. Simulation testing shows that the FE modeling revealed the ability to calculate the stress-strain engineering relationships of perforated steel sheets. It can be concluded that the effect of a perforated rhombus shape is greater than the others, and perforated square shape has no effect on the stress-strain engineering relationships. The efficiency of the perforated staggered or linearly distribution shapes with the actual net area on the applied loads has the opposite effect, as it reduces the load capacity for all types of perforated shapes. Despite the decrease in load capacity, it improves the properties of the steel sheets.

Indicial response functions of growth and remodeling of common bile duct postobstruction

2004 ◽  
Vol 286 (3) ◽  
pp. G420-G427 ◽  
Author(s):  
Quang Dang ◽  
Hans Gregersen ◽  
Birgitte Duch ◽  
Ghassan S. Kassab
Keyword(s):  
Bile Duct ◽  
Common Bile Duct ◽  
Wall Thickness ◽  
Time Course ◽  
Quantitative Description ◽  
Biliary Duct ◽  
Stress And Strain ◽  
Response Functions ◽  
Mechanical Remodeling ◽  
Scheduled Time

Biliary duct obstruction is an important clinical condition that stems from cholelithiasis, the neoplasm in the wall or, most commonly, gallbladder stones. The objective of this study is to understand the structural and mechanical remodeling of the common bile duct (CBD) postobstruction. Porcine CBD was ligated near the duodenum that increased the duct's pressure from 6.4 to 18.3 cmH2O in the first 12 h and to 30.7 cmH2O after 32 days. The remodeling process was studied after 3 h, 12 h, 2 days, 8 days, and 32 days ( n = 5 in each group) after obstruction. One additional animal in each group was sham operated. At each scheduled time, the time course of change of morphometry (diameter, length, wall thickness, etc.) and mechanical properties (stress, strain, etc.) was documented. It was found that the diameter increased by about threefold and the wall thickness of the CBD doubled in the 32-day group compared with the sham group ( P < 0.001). The stress and strain increased initially with increase in pressure but recovered to near the control values by day 32 due to the structural and mechanical adaptations. Hence, the net effect of the structural and mechanical remodeling is to restore the stress and strain to their homeostatic values. Furthermore, the strain recovers more rapidly and more completely than stress. Finally, the remodeling data were expressed mathematically in terms of indicial response functions (IRF), i.e., change of a particular feature of a CBD in response to a unit step change of the pressure. The IRF approach provides a quantitative description of the remodeling process in the CBD.

Finite Element Analysis of Metal Flow of Finishing Groove in Hot Continuous Rolling Bar

2012 ◽  
Vol 510 ◽  
pp. 667-672
Author(s):  
Jia Lin Zhou ◽  
Chen Gang Pan ◽  
Xiao Yong Zhang
Keyword(s):  
Strain Distribution ◽  
Metal Flow ◽  
Dimensional Accuracy ◽  
Stress And Strain ◽  
Fe Model ◽  
Element Analysis ◽  
Iron And Steel ◽  
Expansion Angle ◽  
The Stability ◽  
Stress And Strain Distribution

This article established 3D FE model of dual-radius arc finishing groove and tangent expansion angle finishing groove using ANSYS / LS-DYNA software for Wuhan Iron and Steel plant Ф16 hot continuous bar, and analyzed metal flow pattern, stress and strain distribution of two types finishing grooves. The results show that surface stress and strain distribution of dual-radius arc finishing groove have better uniform than them of tangent expansion angle finishing groove, and dual-radius arc finishing groove ensures the stability of the rolled piece in finishing groove, improve the dimensional accuracy and surface quality of rolled finishing product.

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