Quantitative Analysis of Instability for Superplastic Tension

In conventional analysis of instability, a rough prediction of uniform deformation was obtained due to taking material parameters as constants. In this study, the constitutive equation with varying parameters for Zn-5%Al alloy at 340 °C is employed to predict the critical values of uniform strain in tension based on Considere criterion and Hart criterion, respectively. It should address the factor of strain rate in the characterization of the capability of uniform deformation on superplastic alloys, or for that matter, on any rate-dependent material. Comparison and analysis indicated that the results on Hart criterion have the better predictability of uniform deformation than Considere criterion. The Considere criterion is dependent on strain path, while Hart crtierion is merely dependent on the values of strain and strain rate in tension, and is independent on the strain path or the deformation condition or the deformation history. Therefore, the uniform strain vs. strain rate relation can be taken as a quantitative reference for designing a reasonable strain path during superplastic forming with increase of formability and reduction of forming time.

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

Journal of Engineering Materials and Technology ◽

10.1115/1.3225034 ◽

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.

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Numerical Analysis of Plane-Strain Tension Test for Rate-Dependent Solids

Journal of Applied Mechanics ◽

10.1115/1.2893749 ◽

1992 ◽

Vol 59 (3) ◽

pp. 485-490 ◽

Cited By ~ 2

Author(s):

P. Tugˇcu

Keyword(s):

Numerical Analysis ◽

Strain Rate ◽

Plane Strain ◽

Rate Sensitivity ◽

Tension Test ◽

Engineering Strain ◽

Plane Strain Tension ◽

Rate Dependent ◽

Strain And Strain Rate ◽

Strain Rate Hardening

The plane-strain tension test is analyzed numerically for a material with strain and strain-rate hardening characteristics. The effect of the prescribed rate of straining is investigated for an additive logarithmic description of the material strain-rate sensitivity. The dependency to the imposed strain rate so introduced is shown to have a significant effect on several features of the load-elongation curve such as the attainment of the load maximum, the onset of localization, and the overall engineering strain.

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Investigation of the axial compressive behavior of Kevlar fibers using the dynamic loop test

Textile Research Journal ◽

10.1177/0040517518821898 ◽

2019 ◽

Vol 89 (18) ◽

pp. 3825-3838

Author(s):

Ahmad Abuobaid ◽

Raja Ganesh ◽

John W Gillespie

Keyword(s):

Strain Rate ◽

High Speed ◽

Failure Strain ◽

Kink Band ◽

Test Method ◽

Strain Rates ◽

Compressive Failure ◽

Band Formation ◽

Rate Dependent ◽

Strain And Strain Rate

A dynamic loop test method for measuring strain rate-dependent fiber properties was developed. During dynamic loop testing, the fiber ends are accelerated at constant levels of 20.8, 50 and 343 m/s2. The test method is used to study Kevlar® KM2-600, which fails in axial compression due to kink band formation. The compressive failure strain and strain rate at the onset of kink band formation is calculated from the critical loop diameter ( D C), which is monitored throughout the test using a high-speed camera. The results showed that compressive failure strain increases with strain rates from quasi-static to a maximum strain rate of 116 s−1 by a factor of ∼3. Kink angles (φ) and kink band spacing ( D S) were 60 ° ± 2 ° and 16 ± 3 μm, respectively, over the strain rates tested. Rate-dependent mechanisms of compressive failure by kink band formation were discussed.

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Characterization of Strain Rate-Dependent Behavior of 63Sn-37Pb Solder Using Split Hopkinson Torsional Bars (SHTB)

10.1115/imece2001/epp-24730 ◽

2001 ◽

Author(s):

Shi-Wei Ricky Lee ◽

Lan Hong Dai

Keyword(s):

Solder Joint ◽

Strain Rate ◽

Shear Loading ◽

Rate Dependent ◽

Dependent Behavior ◽

Split Hopkinson ◽

Dynamic Shear Strength ◽

Torsion Bar ◽

Dependent Behaviour

Abstract The present study is aimed at the experimental characterization of strain-rate dependent behaviour of solder materials under impulsive shear loading. In order to achieve this objective, a unique testing technique, namely, split Hopkinson torsion bar (SHTB) is employed. The solder material under investigation is 63Sn-37Pb. The experimental results indicate that the shear behavior of the solder joint is very sensitive to the strain rate and the dynamic shear strength of the solder joint is much higher than the static one.

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High-strain-rate and low temperature superplastic forming of Zn-Al alloy

The Proceedings of the Materials and processing conference ◽

10.1299/jsmemp.2003.11.391 ◽

2003 ◽

Vol 2003.11 (0) ◽

pp. 391-392

Author(s):

Tsutomu TANAKA ◽

Li Fu Chaing ◽

Sung Wook Chung ◽

Koichi MAKII ◽

Atsumichi KUSHIBE ◽

...

Keyword(s):

Low Temperature ◽

High Strain Rate ◽

Strain Rate ◽

High Strain ◽

Superplastic Forming ◽

Al Alloy

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Strain rate-dependent characterization of carbon fibre-reinforced composite laminates using four-point bending tests

Journal of Reinforced Plastics and Composites ◽

10.1177/0731684419879235 ◽

2019 ◽

Vol 39 (5-6) ◽

pp. 165-174

Author(s):

JF Rojas-Sanchez ◽

T Schmack ◽

B Boesl ◽

R Bjekovic ◽

F Walther

Keyword(s):

Carbon Fibre ◽

Strain Rate ◽

Composite Laminates ◽

Tensile Modulus ◽

Bending Tests ◽

Reinforced Plastics ◽

Rate Dependent ◽

Four Point Bending ◽

Carbon Fibre Reinforced Plastics

This research addresses the problem of accurately quantifying the strain rate effect of carbon fibre-reinforced plastics by proposing a method with a simple specimen manufacturing and experiment execution based on four-point bending tests. By easing the strain rate-dependent characterization of carbon fibre-reinforced plastics, less conservative designs can be achieved. The method proposed uses Euler–Bernoulli and Timoshenko’s beam theories to obtain the longitudinal compressive and tensile modulus, compressive strength, shear modulus, and shear yielding point. Transverse properties could not be obtained due to limitations of the fixture employed. A strain-dependent material characterization was done using the proposed method and compared to the characterization of the same material using traditional uniaxial tests. Most of the material properties obtained with different methods correlated within approximately 10%. More work needs to be done to determine how this discrepancy affects simulation results.

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Nanomechanical Characterization of Canine Femur Bone for Strain Rate Sensitivity in the Quasistatic Range under Dry versus Wet Conditions

International Journal of Biomaterials ◽

10.1155/2012/415230 ◽

2012 ◽

Vol 2012 ◽

pp. 1-6 ◽

Cited By ~ 3

Author(s):

Kun-Lin Lee ◽

Marta Baldassarri ◽

Nikhil Gupta ◽

Dinesh Pinisetty ◽

Malvin N. Janal ◽

...

Keyword(s):

Elastic Modulus ◽

Strain Rate ◽

Cross Sections ◽

Mechanical Response ◽

Peak Load ◽

Rate Sensitivity ◽

Rate Dependent ◽

Dry Conditions ◽

Unloading Rate

As a strain rate-dependent material, bone has a different mechanical response to various loads. Our aim was to evaluate the effect of water and different loading/unloading rates on the nanomechanical properties of canine femur cortical bone. Six cross-sections were cut from the diaphysis of six dog femurs and were nanoindented in their cortical area. Both dry and wet conditions were taken into account for three quasistatic trapezoid profiles with a maximum force of 2000 μN (holding time = 30 s) at loading/unloading rates of 10, 100, and 1000 μN/s, respectively. For each specimen,254±9(mean ± SD) indentations were performed under different loading conditions. Significant differences were found for the elastic modulus and hardness between wet and dry conditions (P<0.001). No influence of the loading/unloading rates was observed between groups except for the elastic modulus measured at 1000 μN/s rate under dry conditions (P<0.001) and for the hardness measured at a rate of 10 μN/s under wet conditions (P<0.001). Therefore, for a quasistatic test with peak load of 2000 μN held for 30 s, it is recommended to nanoindent under wet conditions at a loading/unloading rate of 100–1000 μN/s, so the reduced creep effect allows for a more accurate computation of mechanical properties.

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