Influence of the moisture content on the fracture energy and tensile strength of hardwood spotted gum sawn timber and adhesive bonds (gluelines)

Lu, Peiqing; Gilbert, Benoit P.; Kumar, Chandan; McGavin, Robert L.; Karampour, Hassan

doi:10.1007/s00107-023-01999-4

Cited by 8 publications

(2 citation statements)

References 34 publications

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“…This lack of relationship between shear strength and delamination suggests the glueline failures are caused through a motion other than shear. Lu et al (2024) also concluded this where after conducting fracture energy experiments using bonded SPG specimens. Similar studies on the performance of bonded wood products found complimentary results where CYCLED testing presents a significant decrease in bond performance compared to DRY results (Klausler et al, 2013;Faircloth et al, 2023).…”

Section: Rp Samplesmentioning

confidence: 83%

Understanding the Adhesion Performance of Glued Laminated Timber Manufactured with Australian Softwood and High-Density Hardwood Species

Faircloth,

Gilbert,

Kumar

et al. 2024

Preprint

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To be commercialised, glued laminated timber must typically conform to a strict bond integrity assessment. While the associated testing protocols vary slightly from country to country, the general method consists of a series of swelling (water immersion) and shrinkage (drying) cycles. The approach is independent of the species and adhesive type. Those cycles strain the gluelines to a level depending on the species’ moisture uptake, timber dimensional movement and modulus of elasticity, as well as adhesive layer elasticity. High density and high modulus of elasticity materials frequently fail within the glueline regions rather than within the timber and therefore fail the bond integrity assessment. To better understand the mechanisms that lead to glueline failure, glulam samples were manufactured using three prominent Australian commercial timbers of various densities (Radiata pine – Pinus radiata, Southern pine – Pinus caribaea/Pinus elliottii, and Spotted gum – Corymbia citriodora) and two structural adhesive types (resorcinol formaldehyde and polyurethane). Using advanced measurement techniques (digital image correlation and strain gauges), the response of the different species and adhesive types to moisture swelling and shrinkage, as well as times at which glueline separation occurs, were captured. A relationship was observed between moisture uptake and delamination percentages with spotted gum producing significantly higher levels of delamination and significantly lower moisture uptake values, compared to both radiata pine and southern. While the polyurethane glued samples on average produced higher levels of delamination, the digital image correlation data indicates that the time at which this delamination occurs is later than the samples glued with resorcinol formaldehyde. No relationship exists between the block shear strength, wood fibre amounts, and delamination percentages.

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Section: Rp Samplesmentioning

confidence: 83%

Understanding the Adhesion Performance of Glued Laminated Timber Manufactured with Australian Softwood and High-Density Hardwood Species

Faircloth,

Gilbert,

Kumar

et al. 2024

Preprint

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“…Traditional timber buildings often employ logs as structural members to bear loads. However, this approach overlooks the impact of factors such as moisture content, knots, grain direction, and decay on the strength of wood (Lu et al 2024; Pang et al 2021; Zhang et al 2022a; Zhang et al 2021). These defects often lead to deformations and cracks in wood members (Wang et al 2023).…”

Section: Introductionmentioning

confidence: 99%

Research on mechanical properties and fire resistance of flame- retardant laminated veneer lumber fabricated with fast-growing Poplar

Cui,

Chun,

Lin

et al. 2024

Preprint

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To fully utilize Chinese fast-growing timber resources, fast-growing poplar was selected for manufacturing flame-retardant laminated veneer lumber (FRLVL). Firstly, orthogonal experiments were conducted to assess the impact of four factors (hot-pressing time, hot-pressing temperature, retardant concentration, and retardant types) on the mechanical properties and burning behavior of FRLVL. Subsequently, optimal manufacturing parameters were chosen based on statistical analysis. Finally, the fire performance of LVL manufactured with the optimal parameters was evaluated to investigate changes in physical-mechanical properties under high-temperature conditions. Results indicated that the addition of retardants led to a decrease in mechanical properties. In comparison to the control group, LVL composites impregnated with two retardants exhibited a higher limited oxygen index and longer fireproof time, with the effects of ammonium polyphosphate (APP) surpassing those of borax (BX). The optimal manufacturing parameters were a hot-pressing temperature of 140°C, a hot-pressing time of 1.3 min/mm, and concentrations of 15% for both retardant types. As the temperature increased, the mechanical properties of LVL manufactured with the optimal parameters decreased noticeably. However, under the conditions of a temperature of 200°C and a treatment time of 90 min, the mechanical properties of LVL composites still met the LVL-32P grade proposed in LVL handbook.

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Comprehensive analysis of glulam delamination through finite element modelling considering heat and mass transfer, plasticity and fracture mechanics: a case study using high density hardwood

Lu,

Gilbert,

Kumar

et al. 2024

Eur. J. Wood Prod.

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With the ongoing emphasis on sustainable and eco-friendly construction, there is a rising demand for high-strength and high-stiffness engineered wood products. This trend presents both opportunities and challenges for the Australia’s hardwood industry, particularly concerning native forest-grown spotted gum (Corymbia citriodora). Glue laminated (glulam) spotted gum beams cannot be confidently commercialised due to the difficulty for its high-density to satisfy the bond integrity criteria (referred to as “delamination test”) for external products in accordance with the Australia and New Zealand Standard AS/NZS 1328.1. For in-depth understanding of the delamination process, an accurate numerical model represents a valuable and time-efficient tool. The aim of this study is to develop and detail such a model, considering heat and mass transfer, drying stresses, plasticity and fracture propagation models, using COMSOL Multiphysics 5.5. The model was validated against a series of wetting and drying experiments on spotted gum glulam, considering both moisture content variation and crack propagation along the gluelines. Results from the validated model showed that delamination is principally due to the tensile stress applied to the gluelines.

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Influence of the moisture content on the fracture energy and tensile strength of hardwood spotted gum sawn timber and adhesive bonds (gluelines)

Cited by 8 publications

References 34 publications

Understanding the Adhesion Performance of Glued Laminated Timber Manufactured with Australian Softwood and High-Density Hardwood Species

Understanding the Adhesion Performance of Glued Laminated Timber Manufactured with Australian Softwood and High-Density Hardwood Species

Research on mechanical properties and fire resistance of flame- retardant laminated veneer lumber fabricated with fast-growing Poplar

Comprehensive analysis of glulam delamination through finite element modelling considering heat and mass transfer, plasticity and fracture mechanics: a case study using high density hardwood

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