scholarly journals Measurement of Strain and Strain Rate during the Impact of Tennis Ball Cores

2018 ◽  
Vol 8 (3) ◽  
pp. 371 ◽  
Author(s):  
Ben Lane ◽  
Paul Sherratt ◽  
Xiao Hu ◽  
Andy Harland
Keyword(s):  
Strain Rate ◽  
Tennis Ball ◽  
Strain And Strain Rate ◽  
The Impact

Dynamic Strength Estimates for a High Strength, Experimental Steel

2005 ◽  
Author(s):  
Karen L. Torres ◽  
Hollie A. Clements ◽  
Stanley E. Jones ◽  
Morris Dilmore ◽  
Bradley Martin
Keyword(s):  
Strain Rate ◽  
Dynamic Testing ◽  
Dynamic Strength ◽  
High Strength ◽  
High Mass ◽  
Performance Requirements ◽  
Cylinder Test ◽  
Strain And Strain Rate ◽  
Initial Shock ◽  
The Impact

For several years, the Air Force has been engaged in the development of high velocity air to surface missiles. The objective is to replace larger, high mass weapons with smaller, more versatile projectiles that can achieve the same goals. The reduction of mass requires that the impact velocity be increased to meet the performance requirements. This has presented researchers with several challenges. First, the steel must be such that it survives the initial shock at impact. Second, because the tunnel is long, the material must resist friction and wear, which could erode the projectile nose, thereby degrading performance. The purpose of this paper is to present the results of dynamic testing of an experimental, high-strength steel. Using a one-dimensional model for the Taylor cylinder test, the constitutive behavior of the steel as a function of strain and strain-rate can be assessed through a strain-rate of roughly 105/second. This behavior is consistent with that required for successful modeling of the response of a penetrator casing in the ultra-ordinance velocity range.

Dynamic Strength Estimates for a High-Strength Experimental Steel

2008 ◽  
Vol 131 (2) ◽  
Author(s):  
K. L. Torres ◽  
H. A. Clements ◽  
S. E. Jones ◽  
M. Dilmore ◽  
B. Martin
Keyword(s):  
Strain Rate ◽  
Dynamic Testing ◽  
Dynamic Strength ◽  
High Strength ◽  
High Mass ◽  
Performance Requirements ◽  
Cylinder Test ◽  
Strain And Strain Rate ◽  
Initial Shock ◽  
The Impact

For several years, the Air Force has been engaged in the development of high velocity air to surface missiles to defeat hard targets, such as concrete, sand, and soil. The objective is to replace larger, high mass weapons with smaller, more versatile projectiles that can achieve the same goals. The reduction of mass requires that the impact velocity be increased to meet the performance requirements. This has presented researchers with several challenges. First, the steel must be such that it survives the initial shock at impact. Second, because the travel distance in the target is long, the material must resist friction and wear, which could erode the projectile nose, thereby degrading performance. The purpose of this paper is to present the results of dynamic testing of an experimental high-strength steel, also called Eglin steel. Using a one-dimensional model for the Taylor cylinder test, the constitutive behavior of the steel as a function of strain and strain rate can be assessed through a strain rate of roughly 105∕s. This behavior is consistent with that required for successful modeling of the response of a penetrator casing in the ultra-ordinance velocity range.

Abstract 16418: The Impact of MitraClip® Procedure on Left Atrial Strain and Strain Rate

Circulation ◽  
2014 ◽  
Vol 130 (suppl_2) ◽  
Author(s):  
Esra Gucuk Ipek ◽  
Atif Qasim ◽  
Esperanza Viloria ◽  
Ted Feldman ◽  
Paul A Grayburn ◽  
...  
Keyword(s):  
Strain Rate ◽  
Left Atrial ◽  
Atrial Remodeling ◽  
Left Atrial Strain ◽  
Strain And Strain Rate ◽  
One Year ◽  
Atrial Strain ◽  
The Impact ◽  
Strain Measures

Background: Left atrial (LA) remodeling due to mitral regurgitation (MR) is associated with abnormal LA strain parameters which may correlate with degree of fibrosis. Although reverse atrial remodeling has been shown after MitraClip placement, changes in LA strain and strain rate have not been evaluated in these patients or compared with mitral valve repair (MVr). Methods: We measured peak positive LA strain (ε) and strain rates [peak systolic (SRp), peak early diastolic (SRe) and peak late diastolic (SRa)] in 107 subjects (mean age 61±12 yrs) with degenerative MR enrolled in the randomized EVEREST II trial. Individuals with paced rhythm, atrial fibrillation, functional MR and poor image quality were excluded. LA strain measures were obtained from 4-chamber and 2-chamber views and averaged at baseline and at 1 year follow up. Results: At one year all 44 MVr subjects had ≤2+ MR, whereas 22 of the 63 MitraClip had >2+ MR. Baseline average ε, SRp, SRe and SRa values were similar in MitraClip and MVr groups (Table 1). At one year follow up there was a significant decrease in LA volumes in the surgical group and in those with MR ≤2+ after MitraClip. Overall average ε was significantly reduced after MVr. There was a small decrease or no change in average ε after MitraClip. SRe was significantly decreased 1 year after MVr and also in the MitraClip arm, regardless of whether there was significant MR reduction. There were no changes in SRp and SRa at 1 year in either group. Conclusion: Average peak positive LA strain either decreased modestly or did not change after treatment of MR in chronic degenerative MR subjects. There was a significant decrease in SRe in both treatment arms at 1 year. This occurred despite evidence of reverse LA remodeling. Further investigation and replication in additional cohorts is needed to explore these findings, which may suggest persistence of LA dysfunction after correction of chronic MR, or irreversible fibrosis. Disclosure: EVEREST II was funded by Abbott Vascular.

scholarly journals Suggestion of a Framework of Similarity Laws for Geometric Distorted Structures Subjected to Impact Loading

2020 ◽  
Author(s):  
Shuai Wang ◽  
Fei Xu ◽  
Xiaoyu Zhang ◽  
Zhen Dai
Keyword(s):  
Strain Rate ◽  
Impact Loading ◽  
Dynamic Pressure ◽  
Equivalent Stress ◽  
Analytical Models ◽  
Dimensionless Number ◽  
Dimensionless Numbers ◽  
Strain And Strain Rate ◽  
The Impact ◽  
Similarity Laws

A framework of similarity laws, termed oriented-density-length-velocity (ODLV) framework, is suggested for the geometric distorted structures subjected to impact loading. The distinct feature of this framework is that the newly proposed oriented dimensions, dimensionless numbers and scaling factors for physical quantity are explicitly expressed by the characteristic lengths of three spatial directions, which overcome the inherent defects that traditional scalar dimensional analysis could not express the effects of structural geometric characteristics and spatial directions for similarity. The non-scalabilities of geometrical distortion as well as other distortions such as different materials and gravity could be compensated by the reasonable correction for the impact velocity, the geometrical thickness and the density, when the proposed dimensionless number of equivalent stress is used between scaled model and prototype. Three analytical models of beam, plate and shell subjected to impact mass or impulsive velocity are verified by equation analysis. And a numerical model of circular plate subjected to dynamic pressure pulse is verified in more detail, form the view of point of space deformation, deformation history and the components of displacement, strain and stress. The results show that the proposed dimensionless numbers have attractively perfect ability to express the dimensionless response equations of displacement, angle, time, strain and strain rate. When the proposed dimensionless numbers are used to regularize impact models, the structural responses of the geometrically distorted scaled models can behave the completely identical behaviors with those of the prototype on space and time —not only for the direction-independent equivalent stress, strain and strain rate but also for the direction-dependent displacement, stress and strain components.

The effects of strain and strain rate on residual microstructures in copper

1986 ◽  
Vol 44 ◽  
pp. 420-421
Author(s):  
M. F. Stevens ◽  
P. S. Follansbee
Keyword(s):  
Strain Rate ◽  
Applied Stress ◽  
Threshold Stress ◽  
Rate Sensitivity ◽  
Viscous Drag ◽  
Strain Rates ◽  
Strain And Strain Rate ◽  
Threshold Strength ◽  
Mechanism Transition ◽  
Intrinsic Strength

The strain rate sensitivity of a variety of materials is known to increase rapidly at strain rates exceeding ∼103 sec-1. This transition has most often in the past been attributed to a transition from thermally activated guide to viscous drag control. An important condition for imposition of dislocation drag effects is that the applied stress, σ, must be on the order of or greater than the threshold stress, which is the flow stress at OK. From Fig. 1, it can be seen for OFE Cu that the ratio of the applied stress to threshold stress remains constant even at strain rates as high as 104 sec-1 suggesting that there is not a mechanism transition but that the intrinsic strength is increasing, since the threshold strength is a mechanical measure of intrinsic strength. These measurements were made at constant strain levels of 0.2, wnich is not a guarantee of constant microstructure. The increase in threshold stress at higher strain rates is a strong indication that the microstructural evolution is a function of strain rate and that the dependence becomes stronger at high strain rates.

scholarly journals Application of the Strain Compensation Model and Processing Maps for Description of Hot Deformation Behavior of Metastable β Titanium Alloy

Materials ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2021
Author(s):  
Oleksandr Lypchanskyi ◽  
Tomasz Śleboda ◽  
Aneta Łukaszek-Sołek ◽  
Krystian Zyguła ◽  
Marek Wojtaszek
Keyword(s):  
Titanium Alloy ◽  
Strain Rate ◽  
Flow Behavior ◽  
Microstructural Analysis ◽  
Calculated Data ◽  
Processing Temperature ◽  
Processing Maps ◽  
Compression Tests ◽  
Strain And Strain Rate ◽  
Average Absolute Relative Error

The flow behavior of metastable β titanium alloy was investigated basing on isothermal hot compression tests performed on Gleeble 3800 thermomechanical simulator at near and above β transus temperatures. The flow stress curves were obtained for deformation temperature range of 800–1100 °C and strain rate range of 0.01–100 s−1. The strain compensated constitutive model was developed using the Arrhenius-type equation. The high correlation coefficient (R) as well as low average absolute relative error (AARE) between the experimental and the calculated data confirmed a high accuracy of the developed model. The dynamic material modeling in combination with the Prasad stability criterion made it possible to generate processing maps for the investigated processing temperature, strain and strain rate ranges. The high material flow stability under investigated deformation conditions was revealed. The microstructural analysis provided additional information regarding the flow behavior and predominant deformation mechanism. It was found that dynamic recovery (DRV) was the main mechanism operating during the deformation of the investigated β titanium alloy.

A Study of Strain and Strain-Rate Dependent Properties of a Superplastic Zn-Al Alloy Under Biaxial Stresses

1982 ◽  
Vol 104 (1) ◽  
pp. 41-46
Author(s):  
T. C. Hsu ◽  
I. M. Bidhendi
Keyword(s):  
Strain Rate ◽  
Stress Ratio ◽  
Local Stress ◽  
Biaxial Stress ◽  
Al Alloy ◽  
Local Geometry ◽  
Forming Process ◽  
Rate Dependent ◽  
Strain And Strain Rate ◽  
Liquid Behavior

A superplastic Zn-Al alloy in sheet form is formed into a bulge over a circular hole by pneumatic pressure. The geometry, the stress, the strain, and the strain-rate are determined at various points covering the whole specimen and at various stages of the forming process. The complicated shape, and its complicated changes, are represented by introducing an index for the local geometry, called “prolateness,” which is also related to the local stress ratio in a simple way. The biaxial stress is analyzed into a strain-proportional and a strain-rate-proportional component, which represent, respectively, the quasi-solid and the quasi-liquid behavior of the superplastic material.

Effect of Strain Rate on Nb(C,N) Precipitation in Micro Alloy Steel Slab

2012 ◽  
Vol 535-537 ◽  
pp. 633-638 ◽  
Author(s):  
Zheng Hai Zhu ◽  
Sheng Tao Qiu
Keyword(s):  
Continuous Casting ◽  
Strain Rate ◽  
Alloy Steel ◽  
Casting Speed ◽  
Casting Process ◽  
Continuous Casting Process ◽  
Precipitation Model ◽  
Strain And Strain Rate ◽  
Steel Slab

It was analyzed by strain-induced precipitation model that Nb(C,N) precipitation in micro alloy steel slab was effected by strain rate during continuous casting process. The results are as follows: The changing of casting speed could effect the time for 5%precipitation of Nb(C,N), which was decreasing with increasing casting speed at certain temperature and strain rate. Slab strain and strain rate were too small in bending zone and leveling zone. The effect of slab strain rate on Nb(C,N) precipitation could be ignore when Nb(C,N) precipitation in continuous casting process was studied.

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