Measurements of high strain rate properties of polymers using an expanding ring method

Abstract

Trois polymères d'application ingénieure (HDPE, UHMWPE, et Nylatron GS) ont été étudiés à très grande vitesse de déformation (excédant 10 4 /s). On utilisait une technique d'anneau dilaté, qui nécessite le placement d'un fin anneau de polymère, comme bague glissante autour d'un cylindre/creux ayant les murs épais. Un chargement par onde engendré par un fil explosif, abouti au puise de pression qui s'exerce sur le mur interne du cylindre. Ce puise se propage à travers le mur du cylindre et est transféré partielement dans l'anneau. L'anneau se déplace a une grande vitesse du cylindre presque instantanément et en conséquence décélère sous une tension quasiment uniaxiale dû à la contrainte circonférentielle. L'anneau a été photographe avec un appareil de grande vitesse (des cadres de 10 5 à 10 6 /s) et on a pris des mesures duquels les vrais propriétés de déformation et de contrainte étaient déterminés. On a comparé les résultats obtenus du barre d'Hopkinson, en conditions quasistatiques avec les expériences de l'anneau dilaté.

On the Development of New Test Techniques to Measure the Tensile Response of Materials at High and Ultra-high Strain Rates

“…For the case of tensile testing at high or ultra-high strain rates, several authors have explored alternatives to the Hopkinson bar technique, and many of these tests were based on inducing circumferential stress on ring-shaped specimens, using explosives or ballistic impact [9][10][11] or electromagnetic forces [12][13][14][15] as a mean to generating suitable loading pulses. All these tests were demonstrated on ductile materials (metals in most cases) and all of them were not suitable to measure stress versus strain curves, which are in high demand by the materials modelling community.…”

A new technique for tensile testing of engineering materials and composites at high strain rates

“…Several authors [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23] have struggled to conduct dynamic measurements on the tensile response of high-performance fibres and tapes. For this type of materials, it is difficult to achieve force equilibrium during SHPB tests, and specimens are typically limited to only a few millimetres (mm) in length.…”

“…Using a similar set-up, Warnes et al [15] achieved strain rates up to 2.3 × 10 4 s −1 testing the plastic dynamic response of annealed copper. Maliky & Parry [16] studied the dynamic response of three engineering polymers at a strain rate of 10 4 s −1 , while Tang et al [17] tested copper samples using a similar technique.…”

Fabrication and characterization of novel hybrid nanocomposites with application in solar cells

“…The strain in material yielding was high and almost the same for all the dummy cells and the investigated strain rates, demonstrating the ability of the systems to undergo large elastic deformations, needed for the development of flexible solar cells. The shape of stress-strain curve of a polymeric material strongly depends on strain rate [597][598][599]. Depending on the strain rate, the relaxation time that the material has to respond to the external loads alters.…”