Development of a torsion pendulum and its application to measuring the dynamic modulus of adhesives from pre-gelation to the cured state

Yu, Hongkun; Adams, Robert D.; Silva, Lucas F. M. da

doi:10.1088/0957-0233/25/5/055603

Cited by 9 publications

(8 citation statements)

References 14 publications

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“…For two centuries, the torsion pendulum/balance has been considered as one of the most precise tools to measure weak forces since the landmark works by Coulomb [15] and Cavendish [16,17], and has been widely used in experimental physics [18,19], materials science [20][21][22] and other areas of engineering [23]. Both torsion pendulum [3,4,9,12,[24][25][26][27][28] and torsion balance [14,22,[29][30][31][32][33][34][35] have been used to measure the torsional properties of individual fibers.…”

Section: Introductionmentioning

confidence: 99%

An improved torsion pendulum based on image processing for single fibers

Yu¹,

Liu²,

Peng³

et al. 2016

Meas. Sci. Technol.

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An improved torsion pendulum technique based on image processing is developed, which allows the measurement of the torsional oscillation of individual fibers. The torsion pendulum is composed of a length of fiber specimen and a ring-shaped mass attached to one of its ends. The oscillation motion of the mass is recorded with a video camera overhead. An image processing method is developed to accurately calculate the twist angle of single fibers in the torsion pendulum. All images are firstly converted into matrices and then the edge detection is applied to calculate the twist angle at corresponding time to obtain the angle-time relation. The oscillation frequency is determined by the fast Fourier transform (FFT) method. By applying this technique, we have performed tests on four types of fibers, namely T300 carbon fiber, copper, silver and tungsten wires. The longitudinal shear modulus measured for each type of these fibers is presented.

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Section: Introductionmentioning

confidence: 99%

An improved torsion pendulum based on image processing for single fibers

Yu¹,

Liu²,

Peng³

et al. 2016

Meas. Sci. Technol.

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“…Moreover, there are reports that the elastic modulus values obtained from DMA show large discrepancies between specimens and are in many cases different from those measured by quasi-static mechanical tests, as can be seen in the paper of Deng et al [11]. Another promising dynamic test method is the novel torsion pendulum test developed by Yu et al [12]. This technique allows measuring the dynamic shear modulus of adhesives since the early stages of the cure, monitoring the change of the resonant frequency with time.…”

Section: Introductionmentioning

confidence: 99%

Monitoring the early stiffness development in epoxy adhesives for structural strengthening

Granja

Fernandes

Benedetti

et al. 2015

International Journal of Adhesion and Adhesives

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a b s t r a c tThe present work aimed to assess the early-age evolution of E-modulus of epoxy adhesives used for Fibre-Reinforced Polymer (FRP) strengthening applications. The study involved adapting an existing technique devised for continuous monitoring of concrete stiffness since casting, called EMM-ARM (Elasticity Modulus Measurement through Ambient Response Method) for evaluation of epoxy stiffness. Furthermore, monotonic tensile tests according to ISO standards and cyclic tensile tests were carried out at several ages. A comparison between the obtained results was performed in order to better understand the performance of the several techniques in the assessment of stiffness of epoxy resins. When compared to the other methodologies, the method for calculation of E-modulus recommended by ISO standard led to lower values, since in the considered strain interval, the adhesive had a non-linear stress-strain relationship. The EMM-ARM technique revealed its capability in clearly identifying the hardening kinetics of epoxy adhesives, measuring the material stiffness growth during the entire curing period. At very early ages the values of Young's modulus obtained with quasi-static tests were lower than the values collected by EMM-ARM, due to the fact that epoxy resin exhibited a significant visco-elastic behaviour.

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“…The torsion pendulum is used to monitor the properties evolution at small strains due to its versatility and easy customization [ 21 , 22 ]. Since its appearance more than two centuries ago [ 23 ], the torsion pendulum has been extensively used for material characterization [ 24 , 25 , 26 , 27 ], and its specific applicability to rubber and filler reinforced rubber systems has been previously established [ 19 , 28 , 29 , 30 , 31 ]. Furthermore, the torsion pendulum allows for long testing times, a crucial requirement for physical aging measurements [ 16 ].…”

Section: Methodsmentioning

confidence: 99%

Evolution of the Viscoelastic Properties of Filler Reinforced Rubber under Physical Aging at Room Temperature

et al. 2023

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Filler reinforced rubber is widely used for engineering applications; therefore, a sound characterization of the effects of physical aging is crucial for accurately predicting its viscoelastic properties within its operational temperature range. Here, the torsion pendulum is used to monitor the evolution of the storage and loss modulus of carbon black filled samples for four days after a temperature drop to 30 °C. The storage modulus presents a continuous increase, while the loss modulus generally displays a steady decrease throughout the four days that each test was conducted. The relationship of the recovery rates with the carbon black properties is also studied, analysing its dependency on the particle size and aggregate structure. The evolution of the recovery rate seems to depend linearly on the surface area while the carbon black structure appears to have a much weaker influence on the physical aging behavior for the set of compounds tested. The obtained results corroborate the presence of physical aging at room temperature for filler rubber materials and the ability of the torsion pendulum to monitor the storage and loss modulus change, providing pivotal data on the influence of physical aging on the viscoelastic properties of the material.

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Development of a torsion pendulum and its application to measuring the dynamic modulus of adhesives from pre-gelation to the cured state

Cited by 9 publications

References 14 publications

An improved torsion pendulum based on image processing for single fibers

An improved torsion pendulum based on image processing for single fibers

Monitoring the early stiffness development in epoxy adhesives for structural strengthening

Evolution of the Viscoelastic Properties of Filler Reinforced Rubber under Physical Aging at Room Temperature

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