Digital image correlation as a strain measurement technique for fibre tensile tests

Abstract

A method is presented to test fibres in tension using direct strain measurement. This eliminates the need to test the fibres at multiple gauge lengths to correct for machine compliance, reducing the number of samples. Additionally, fibre slippage can contribute to the underestimation of the stiffness since this is not considered in the correction procedure. Steel fibres with a diameter of 30 µm, and a known stiffness of 193 GPa, were tested in tension using indirect methods and the direct strain method. Direct strain measurement resulted in a stiffness of 187 ± 12 GPa while the lowest and highest stiffness obtained by the indirect methods are 140 ±2 GPa and 150 ± 4 GPa.The underestimation by the indirect measurement strain methods show the need for a new

Bamboo fibres sourced from three global locations: A microstructural, mechanical and chemical composition study

“…An overview of the mechanical properties found in literature of technical bamboo fibres is given in Table 1 of Depuydt et al. 38 Young’s moduli vary between 19 and 43 GPa and strength between 341 and 860 MPa. Different factors can be responsible for the large variation.…”

Effect of enzymatic treatment of flax on fineness of fibers and mechanical performance of composites

“…A digital camera with a spatial resolution of 96 dpi was used to record the speckle pattern applied to the sample. The distance between composite sample and camera was 1 m. During the test, subsequent images and force registration were taken with an interval of 150 ms[46]. Images were further analyzed with VIC-2D 2009 software to calculate the strain.…”

Low‐temperature compounding of flax fibers with polyamide 6 via solid‐state shear pulverization: Towards viable natural fiber composites with engineering thermoplastics

“…In terms of stiffness, the addition of scutched flax enhanced both tensile and flexural moduli of PA6 significantly. The modulus increase is expected because the reported elastic modulus of flax is 45–60 GPa . However, the extent of stiffness enhancement is dictated by the processing methodology.…”

“…revealed that the lack of compounding kept the flax fibers in MIXsc mostly in their original, bundled technical fibers state. Based on previous studies that have reported slightly lower tensile modulus for technical fibers (~45 GPa) in reference to elementary fibers (60 GPa) , the E f quantity in Eq . is then an averaged technical/elementary fiber stiffness, which would be lower for MIXsc than SSSPsc.…”

“…One technical fiber is made up of 10–40 individual fiber entities called elementary fibers, which are 2–5 cm in length and 10–20 μm in diameter. Considering the tensile strength of elementary fibers of ~1,300 MPa compared with that of technical fibers at ~600 MPa , a desired state of flax reinforcement is one where individual elementary fibers are well‐dispersed (i.e., separated) and distributed (spread) within the polymer matrix.…”