Dynamic behavior and damping characteristics of carbon black polymer composites at high strain rates

Abstract Stress softening of carbon black reinforced butadiene styrene rubber was studied as a function of the rate and temperature of the original tensile deformation. To a good approximation, stress softening depends on the product of the extension rate and a temperature function which is analytically well represented by the familiar Williams-Landel-Ferry relationship. When the elongation of the original deformation is also varied, a good correlation is obtained between stress softening and the maximum stress attained in the original extension, irrespective of the particular combination of strain, strain rate, and temperature used to achieve this stress. Variables which tend to increase the stiffness of the vulcanizate, such as increased degree of crosslinking or carbon black chain structure, also increase stress softening; dilution by plasticizers decreases it. Prestressing at high strain rates and low temperatures affects the stress—strain curve of the softened vulcanizates beyond the elongation of the original extension. Connections are established between stress softening and viscoelastic and failure behavior. The evidence presented favors the contribution of several mechanisms to the general phenomenon of stress softening. These are thixotropy of transient filler structures, network chain rupture, and breakage of “permanent” filler structure. The latter appears to be most important at high strain rates, low temperatures, and with highly reticulated “structure” blacks.

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Dynamic Behavior of Metals at Elevated Temperatures and Ultra-High Strain Rates

Proceedings ◽

10.3390/icem18-05204 ◽

2018 ◽

Vol 2 (8) ◽

pp. 372

Author(s):

Tianxue Wang ◽

Bryan Zuanetti ◽

Vikas Prakash

Keyword(s):

Dynamic Behavior ◽

Elevated Temperatures ◽

High Strain ◽

Strain Rates ◽

High Strain Rates

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Approaches to Synchronise Conventional Measurements with Optical Techniques at High Strain Rates

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.70.75 ◽

2011 ◽

Vol 70 ◽

pp. 75-80 ◽

Cited By ~ 3

Author(s):

Duncan A. Crump ◽

Janice M. Dulieu-Barton ◽

Marco L. Longana

Keyword(s):

Polymer Composites ◽

High Speed ◽

High Strain ◽

Image Correlation ◽

Test Machine ◽

Strain Rates ◽

High Strain Rates ◽

Optical Techniques ◽

Specific Loading ◽

Military Applications

Polymer composites are increasingly being used in high-end and military applications, mainly due to their excellent tailorability to specific loading scenarios and strength/stiffness to weight ratios. The overall purpose of the research project is to develop an enhanced understanding of the behaviour of fibre reinforced polymer composites when subjected to high velocity loading. This is particularly important in military applications, where composite structures are at a high risk of receiving high strain rate loading, such as those resulting from collisions or blasts. The work described here considers an approach that allows the collection of full-field temperature and strain data to investigate the complex viscoelastic behaviour of composite material at high strain rates. To develop such a data-rich approach digital image correlation (DIC) is used to collect the displacement data and infra-red thermography (IRT) is used to collect temperature data. The use of optical techniques at the sampling rates necessary to capture the behaviour of composites subjected to high loading rates is novel and requires using imaging systems at the far extent of their design specification. One of the major advantages of optical techniques is that they are non-contact; however this also forms one of the challenges to their application to high speed testing. The separate camera systems and the test machine/loading system must be synchronised to ensure that the correct strain/temperature measurement is correlated with the correct temporal value of the loading regime. The loading rate exacerbates the situation where even at high sampling rates the data is discrete and therefore it is difficult to match values. The work described in the paper concentrates on investigating the possibility of the high speed DIC and synchronisation. The limitations of bringing together the techniques are discussed in detail, and a discussion of the relative merits of each synchronisation approach is included, which takes into consideration ease of use, accuracy, repeatability etc.

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