Poisson's ratio bounds in orthotropic materials. Application to natural composites: wood, bamboo and Arundo donax

Mentrasti, Lando; Molari, Luisa; Fabiani, Marco

doi:10.1016/j.compositesb.2021.108612

Cited by 16 publications

(3 citation statements)

References 21 publications

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“…While the specimen with positive PR gives a Poisson's ratio ν of 0.65 ± 0.05, the specimen with negative PR gives a ν of 0.82 ± 0.01. These Poisson's ratios arecontrary to the limits of −1 to 0.5 for isotropic materials (Ting and Chen 2005)possible and in accordance with theoretical (Mentrasti et al 2021) and experimental literature (Kumpenza et al 2018) on orthotropic materials like wood. This leads to the conclusion that the compression in direction of the x-axis, which is identical with the direction of the resistance measurement, is relatively higher compared to the tension perpendicular to the measurement direction.…”

Section: Strain Analysissupporting

confidence: 89%

Piezoresistive bond lines for timber construction monitoring—experimental scale-up

et al. 2021

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Several laboratory studies and experiments have demonstrated the usability of polymer films filled with electrically conductive filler as piezoresistive material. Applied to adhesives, the glue lines of wood products can achieve multifunctional—thus bonding and piezoresistive/strain sensing—properties. Based on critical load areas in timber constructions, upscaled test setups for simplified load situations were designed, especially with regard to a stress-free electrical contact. In a second step, another upscaling was done to small glulam beams. Based on an experimental test sequence, the piezoresistive reactions as well as the behaviour until failure were analysed. The results show in all cases that a piezoresistive reaction of the multifunctionally bonded specimens was measurable, giving a difference in the extent of relative change. Additionally, measured phenomena like inverse piezoresistive reactions, electrical resistance drift and the absence of a piezoresistive reaction were discussed, based on additional strain analysis by digital image correlation. A model of macroscopic and microscopic strains influencing the piezoresistive reaction of the electrically conductive bond line in wood was used to explain all experimental results. Finally, a first scale-up of piezoresistive bond lines from laboratory samples to glulam beams was possible and successful.

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Section: Strain Analysissupporting

confidence: 89%

Piezoresistive bond lines for timber construction monitoring—experimental scale-up

et al. 2021

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“…The modulus of elasticity in the tangential direction (T) was fixed to a constant of 500 MPa, and all other moduli were calculated as ratios of the modulus 582 in tangential direction (EL : ER : ET = 20 : 1.6 : 1, GLR : GLT : GRT = 10 : 9.4 : 1 and EL : GLR = 14 : 1). Three Poisson's ratios were estimated to be RL = 0.02, LT = 0.02 and RT = 0.35 based on values of tropical hardwood species [8][9][10][11][15][16][17][18]. Only a half of the specimen was generated to reduce the computational time because the specimen had a plane of symmetry in the RT-plane as shown in Fig.…”

Section: Finite Element Model Of the Restrained Half-split Specimenmentioning

confidence: 99%

Assessment of Asymmetrical Stress Profile within Wood Using Restoring Force Technique

Leelatanon¹,

Jantawee²,

Vannarat³

et al. 2022

Int. j. simul. model.

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Asymmetrical internal stress profile within the kiln-dried lumber assessed using the restoring force technique on the half-split specimen has been investigated. Unlike the symmetrical internal stress profile in which the measured restoring force is completely described by an elastic beam theory, the asymmetrical internal stress profile also induces a so-called remnant force. By using the released strain and the elastic modulus data across the entire thickness obtained from the McMillen slice test, a numerical result based on the finite element model successfully simulates the restoring force profile for an entire range of both symmetric and asymmetric stress profiles. The finite element model is leveraged to evaluate the effect of asymmetry of stress profile on the remnant force. The value of the remnant force linearly depends on the stress profile deviation which is inferred to the level of asymmetric stress profile.

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“…In the present research, Arundo donax fibers were used to modify an alkali-activated matrix based on fly ash. Arundo donax has remarkable mechanical properties that have been investigated previously [29,30] and that make this material quite interesting in the building industry. This plant has been used in the past to formulate organic polymerbased composites [31,32], or even to produce hybrid composites with an inorganic/organic matrix [33].…”

Section: Introductionmentioning

confidence: 99%

Alkali-Activated Mortars Reinforced with Arundo donax: Properties and Durability to Environmental Stresses

et al. 2023

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Natural fibers were used to modify alkali-activated fly-ash mortars. Arundo donax is a common, fast-growing, widespread plant with interesting mechanical properties. Short fibers of different lengths (from 5 to 15 mm) were added at a 3 wt% ratio to the binder amount to the alkali-activated fly-ash matrix. The possible effects on the fresh and cured properties of the mortars deriving from the different lengths of the reinforcing phase were investigated. The flexural strength of the mortars increased by up to 30% at the longest fiber dimensions, while the compressive strength remained almost unchanged in all of the compositions. The dimensional stability was increased slightly upon the addition of the fibers, depending on the fiber length, while the porosity of the mortars was reduced. Moreover, contrary to what was expected, the water permeability was not increased by the fibers’ addition, irrespective of their length. The durability of the obtained mortars was tested through freeze–thaw and thermo-hygrometric cycles. The results obtained so far underline a fair resistance to the changes in temperature and moisture and a better resistance to the freeze–thaw stresses of the reinforced mortars.

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Poisson's ratio bounds in orthotropic materials. Application to natural composites: wood, bamboo and Arundo donax

Cited by 16 publications

References 21 publications

Piezoresistive bond lines for timber construction monitoring—experimental scale-up

Piezoresistive bond lines for timber construction monitoring—experimental scale-up

Assessment of Asymmetrical Stress Profile within Wood Using Restoring Force Technique

Alkali-Activated Mortars Reinforced with Arundo donax: Properties and Durability to Environmental Stresses

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