Nanoscale repetitive impact testing of polymer films

2004 ◽  
Vol 19 (1) ◽  
pp. 237-247 ◽  
Author(s):  
Ben D. Beake ◽  
Stephen R. Goodes ◽  
James F. Smith ◽  
Fengge Gao
Keyword(s):  
Plastic Deformation ◽  
Strain Rate ◽  
Polymer Films ◽  
High Strain ◽  
Fatigue Behavior ◽  
Indentation Test ◽  
Impact Testing ◽  
Thin Polymer Film ◽  
Poly Ethylene ◽  
The Impact

The deformation of polymer films under repetitive contact at high strain rates was investigated using nanoscale impact testing. Four systems were studied: (i) rubber-modified acrylonitrile-butadiene-styrene (ABS) (0–25 wt% rubber), (ii) uniaxially and biaxially drawn poly(ethylene terephthalate) film; (iii) poly(ethylene oxide)–clay nanocomposites, and (iv) nylon 6–organoclay nanocomposites. The initial results suggest that the technique has much potential in evaluating the fatigue behavior of thinner polymer films and coatings that are unsuitable for conventional methods designed for bulk samples. The extent of impact-induced deformation may be used as a measure of ductility because ductile failures are associated with significant plastic deformation before failure whereas brittle failures usually involve little plastic deformation. The nano-impact technique provides valuable highly localized information about deformation under high strain rate, which is complementary to low strain rate tests such as nanoindentation and nano-scratch. The technique has been shown to be sensitive to nano-/microstructural variations in ABS–rubber film when Berkovich indenters and low impact forces were used. The impact behavior of the nanocomposites is only significantly worse than that of the virgin polymers at the highest clay loading studied (15 wt%). This could be a factor when assessing the suitability of novel nanocomposite materials for applications where toughness is important. On ABS film, there is only an approximate correlation between the plastic work function determined from nanoindentation and the rubber loading in the film while the correlation between the rubber loading and nano-impact data is clear, suggesting that the dynamic test is a more useful predictor of thin polymer film toughness than the slow-loading quasi-static indentation test.

scholarly journals A New Set-Up to Investigate Plastic Deformation of Face Centered Cubic Metals in High Strain Rate Loading

2014 ◽  
Vol 8 (2) ◽  
Author(s):  
Ehsan Etemadi ◽  
Jamal Zamani ◽  
Alessandro Francesconi ◽  
Mohammad V. Mousavi ◽  
Cinzia Giacomuzzo
Keyword(s):  
Plastic Deformation ◽  
High Strain Rate ◽  
Strain Rate ◽  
High Strain ◽  
Face Centered Cubic ◽  
Cubic Metals ◽  
Face Centered ◽  
Set Up ◽  
Strain Rate Loading

scholarly journals Carbon Nanotube Peapods Under High-Strain Rate Conditions: A Molecular Dynamics Investigation

MRS Advances ◽  
2020 ◽  
Vol 5 (33-34) ◽  
pp. 1723-1730
Author(s):  
J. M. De Sousa ◽  
C. F. Woellner ◽  
L. D. Machado ◽  
P. A. S. Autreto ◽  
D. S. Galvao
Keyword(s):  
Molecular Dynamics ◽  
Carbon Nanotube ◽  
High Strain Rate ◽  
Strain Rate ◽  
High Strain ◽  
Optical Modulation ◽  
Carbon Structures ◽  
Dynamics Simulations ◽  
Forms Of Carbon ◽  
The Impact

ABSTRACTNew forms of carbon-based materials have received great attention, and the developed materials have found many applications in nanotechnology. Interesting novel carbon structures include the carbon peapods, which are comprised of fullerenes encapsulated within carbon nanotubes. Peapod-like nanostructures have been successfully synthesized, and have been used in optical modulation devices, transistors, solar cells, and in other devices. However, the mechanical properties of these structures are not completely elucidated. In this work, we investigated, using fully atomistic molecular dynamics simulations, the deformation of carbon peapods under high-strain rate conditions, which are achieved by shooting the peapods at ultrasonic velocities against a rigid substrate. Our results show that carbon peapods experience large deformation at impact, and undergo multiple fracture pathways, depending primarily on the relative orientation between the peapod and the substrate, and the impact velocity. Observed outcomes include fullerene ejection, carbon nanotube fracture, fullerene, and nanotube coalescence, as well as the formation of amorphous carbon structures.

Micro Impact Testing of Lead Free Solder Joints

2008 ◽  
Vol 32 ◽  
pp. 99-102
Author(s):  
Ranjan Rajoo ◽  
Erich H. Kisi ◽  
D.J. O'Connor
Keyword(s):  
Solder Joint ◽  
High Strain Rate ◽  
Strain Rate ◽  
High Strain ◽  
Intermetallic Layer ◽  
Displacement Transducer ◽  
Impact Testing ◽  
Lead Free ◽  
Linear Variable Displacement Transducer ◽  
Free Solder

This paper presents data obtained from a newly-developed instrument to test the quality of solder interconnections at high strain rate – the ‘micro-impactor’. This shear test of the interconnection at high strain rate mimics the stress experienced by the solder joint when undergoing shock due to drop-impact. Instrumented with a load cell and linear variable displacement transducer (LVDT), it also has the ability to provide dynamic impact force and displacement data. Earlier concepts to characterise the solder joint at high strain rates such as the miniature pendulum impact tester [1] lacked this capability. This micro-impactor was used to study the effect of increasing silver (Ag) and copper (Cu) concentration in solder alloys on the shear strength of the solder joint. The performance of these lead-free alloys was also compared to that of the well-established leaded solder. It was found that increasing the silver content increases the yield strength of the solder, causing the failure to occur at the brittle intermetallic layer instead of in the bulk of the solder.

Comparative Study of the Dynamic Behavior of AA2519 Aluminum Alloy in T6 and T8 Temper Conditions

2019 ◽  
Author(s):  
Adewale Olasumboye ◽  
Gbadebo Owolabi ◽  
Olufemi Koya ◽  
Horace Whitworth ◽  
Nadir Yilmaz
Keyword(s):  
Plastic Deformation ◽  
Aluminum Alloy ◽  
Stress Response ◽  
Flow Stress ◽  
Yield Strength ◽  
Strain Rate ◽  
High Strain ◽  
Second Phase ◽  
Strain Rates ◽  
High Strain Rates

Abstract This study investigates the dynamic response of AA2519 aluminum alloy in T6 temper condition during plastic deformation at high strain rates. The aim was to determine how the T6 temper condition affects the flow stress response, strength properties and microstructural morphologies of the alloy when impacted under compression at high strain rates. The specimens (with aspect ratio, L/D = 0.8) of the as-cast alloy used were received in the T8 temper condition and further heat-treated to the T6 temper condition based on the standard ASTM temper designation procedures. Split-Hopkinson pressure bar experiment was used to generate true stress-strain data for the alloy in the range of 1000–3500 /s strain rates while high-speed cameras were used to monitor the test compliance with strain-rate constancy measures. The microstructures of the as received and deformed specimens were assessed and compared for possible disparities in their initial microstructures and post-deformation changes, respectively, using optical microscopy. Results showed no clear evidence of strain-rate dependency in the dynamic yield strength behavior of T6-temper designated alloy while exhibiting a negative trend in its flow stress response. On the contrary, AA2519-T8 showed marginal but positive response in both yield strength and flow behavior for the range of strain rates tested. Post-deformation photomicrographs show clear disparities in the alloys’ initial microstructures in terms of the second-phase particle size differences, population density and, distribution; and in the morphological changes which occurred in the microstructures of the different materials during large plastic deformation. AA2519-T6 showed a higher susceptibility to adiabatic shear localization than AA2519-T8, with deformed and bifurcating transformed band occurring at 3000 /s followed by failure at 3500 /s.

scholarly journals Dynamic Mechanical Compression Impulse of Lithium-Ion Pouch Cells

Energies ◽  
2020 ◽  
Vol 13 (8) ◽  
pp. 2105 ◽  
Author(s):  
Alon Ratner ◽  
Richard Beaumont ◽  
Iain Masters
Keyword(s):  
Mechanical Properties ◽  
Strain Rate ◽  
Strain Rate Sensitivity ◽  
Lithium Ion ◽  
Rate Sensitivity ◽  
Dynamic Mechanical Properties ◽  
Impact Testing ◽  
Significant Feature ◽  
Dynamic Mechanical ◽  
The Impact

Strain rate sensitivity has been widely recognized as a significant feature of the dynamic mechanical properties of lithium-ion cells, which are important for their accurate representation in automotive crash simulations. This research sought to improve the precision with which dynamic mechanical properties can be determined from drop tower impact testing through the use of a diaphragm to minimize transient shock loads and to constrain off-axis motion of the indenter, specialized impact absorbers to reduce noise, and observation of displacement with a high speed camera. Inert pouch cells showed strain rate sensitivity in an increased stiffness during impact tests that was consistent with the poromechanical interaction of the porous structure of the jellyroll with the liquid electrolyte. The impact behaviour of the inert pouch cells was similar to that of an Expanded Polypropylene foam (EPP), with the exception that the inert pouch cells did not show hysteretic recovery under the weight of the indenter. This suggests that the dynamic mechanical behaviour of the inert pouch cells is analogous to a highly damped foam.

High strain rate superplasticity of submicrometer grained 5083 Al alloy containing scandium fabricated by severe plastic deformation

2003 ◽  
Vol 341 (1-2) ◽  
pp. 273-281 ◽  
Author(s):  
Kyung-Tae Park ◽  
Duck-Young Hwang ◽  
Young-Kook Lee ◽  
Young-Kuk Kim ◽  
Dong Hyuk Shin
Keyword(s):  
Plastic Deformation ◽  
Severe Plastic Deformation ◽  
High Strain Rate ◽  
Strain Rate ◽  
High Strain ◽  
Al Alloy ◽  
5083 Al Alloy

Behavior Evaluation of Deformation, Damage and Fracture of Biological Soft Tissue by Using Indentation Test

2016 ◽  
Author(s):  
Atsushi Sakuma ◽  
Katsuya Igarashi
Keyword(s):  
Stress Response ◽  
Soft Tissue ◽  
Deformation Behavior ◽  
Reaction Force ◽  
Indentation Test ◽  
Impact Testing ◽  
Ball Impact ◽  
Damage And Fracture ◽  
The Impact ◽  
Biological Soft Tissue

In this study, two types of indentation tests were used for the observation of deformation behavior of biological soft tissue, because indentation testing is an easy method to manage observation and control of the condition of complex tissue specimens. First, a fundamental indentation test was used to evaluate quasi-static deformation behavior of soft tissue. In the evaluation of the quasi-static behavior, elasticity, damage, and fracture of the tissue were analyzed from the profile of reaction force during the indentation. Ball-impact testing with subsonic indentation velocity was used for the evaluation of dynamic behaviors of soft tissue. In the impact test, the viscoelastic characteristics of specimens were evaluated by analyzing stress response, using extended Hertzian contact theory and wave equations, at the moment when a simple ball bullet shot from an airsoft gun strikes the specimen. In the experimental results of the test, an obvious relationship between quasi-static and impact responses of the specimen were observed subjectively. The results are evaluated to analyze the damage and the fracture of the soft tissue for the objective formulation of tissue mechanics. The plateau behavior of reaction force in relation to stress response was also reviewed, in order to quantify the beginning of tissue fracture.

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