Nonlinear mechanical behaviour and analysis of wood and fibre materials

Holmberg, Stefan; Persson, Kent; Petersson, Hans

doi:10.1016/s0045-7949(98)00331-9

Cited by 108 publications

(77 citation statements)

References 8 publications

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“…Several studies have been conducted to optimize the theoretical basis aiming to determine shear modulus in wood, considering its features of orthotropy, being mentioned among them Gillis (1972), Holmberg, Persson, and Petersson (1999), Nairn (2007), Price (1929), andSchniewind (1959). These authors have contributed to better understanding of the problem, usually working with the well-known tests in clear specimens.…”

Section: Introductionmentioning

confidence: 99%

<b>Shear and longitudinal modulus of elasticity in wood: relations based on static bending tests

et al. 2017

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ABSTRACT. Improve quality of timber structures design is an aim that must be systematically sought by engineers in this area. An important topic that can contribute directly to be achieved in this subject is the more consistent knowledge related to structural properties of wood. Know values of longitudinal modulus of elasticity (E) and shear modulus (G) is essential for proper evaluation of plate structures performance, as example. It has been usual to adopt statistical equivalence for E and G values in plans longitudinal-radial and longitudinal-tangential, although experimental confirmation of this hypothesis is required. In this context, the aim of this work is to determine values of E LR , E LT , G LR and G LT , based on static bending tests, to five dicotyledonous species. Results showed statistical equivalence between the elastic properties in both plans, and the relation E = 35G was obtained for the five wood species here considered.Keywords: static bending test, timber, shear modulus, longitudinal modulus of elasticity.Módulo de elasticidade transversal e longitudinal da madeira: relações baseadas nos ensaios de flexão RESUMO. Melhorias no projeto das estruturas de madeira são metas que devem ser sistematicamente almejadas por profissionais da área. Um tópico importante que pode contribuir diretamente para isso está relacionado a um conhecimento mais profundo a respeito das propriedades de resistência e de rigidez da madeira. O conhecimento dos módulos de elasticidade longitudinal (E) e transversal (G) é essencial para a avaliação do desempenho de placas entre outros elementos estruturais. No dimensionamento estrutural tem sido comum adotar equivalência estatística dos valores de E e G nas direções longitudinal-radial e longitudinais-transversal. Este trabalho objetivou determinar valores dos módulos de elasticidade E LR , E LT , G LR e G LT com base em testes de flexão estática para cinco espécies dicotiledôneas, possibilitando avaliar a equivalência ou não destas propriedades (E LR e E LT ; G LR e G LT ) assim como de estabelecer correlações adequadas entre E e G. Os resultados revelaram equivalência estatística entre as propriedades elásticas em ambas as direções, e a relação E = 35·G foi obtida para espécies de madeira estudadas.Palvras-chave: ensaio de flexão estática, madeira, módulo de elasticidade transversal, módulo de elasticidade longitudinal.

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Section: Introductionmentioning

confidence: 99%

<b>Shear and longitudinal modulus of elasticity in wood: relations based on static bending tests

et al. 2017

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“…The cell geometry, using either the actual cellular layout or synthetic or average dimensions, has been used in many instances to calculate material properties, like density, permeability (e.g., Badel and Perré 2003), mechanical properties (Badel and Perré 2007, Hofstetter et al 2005, Qing and Mishnaevsky 2009, and even deformation and fracturing (Holmberg et al 1999), using different computational techniques. These studies use either a microscopic image of a limited number of cells or average dimensions, often taken from literature.…”

Section: Introductionmentioning

confidence: 99%

Variation of measured cross-sectional cell dimensions and calculated water vapor permeability across a single growth ring of spruce wood

2011

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A statistical study of the cell dimensions in a growth ring of spruce along the radial and tangential directions is performed. The data are used to study the variation of the cell vapor permeability in the growth ring. Studying cell rows within one growth ring, the frequency distributions of the cell wall thickness in the radial direction and of the lumen dimension in the tangential direction are found to be both unimodal. In contrast, the frequency distributions of these dimensions in the other directions are bimodal, where the different modes can be attributed to earlywood and latewood. Analysis of the bimodal distributions results in the determination of threshold values of cell wall thickness and the lumen dimension for earlywood and latewood tracheids. The cell dimensions are used to predict cell porosity and water vapor permeability distribution within a growth ring. The bimodal frequency distributions of the tangential cell wall thickness and the radial lumen dimension provide an explanation for the observed bimodal frequency distribution of the cell water vapor permeability both in radial and in tangential directions. Contrary to measured macroscopic vapor permeability results, the tracheid geometry results in lower cell vapor permeability in radial than in tangential direction. This confirms that rays play an important role in the vapor permeability of D. Derome (&) Fluids and porous materials, EMPA, Ü berlandstrasse 129,

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“…Se tomaron elementos tridimensionales hexagonales con denominación "C3D8R" de la biblioteca de elementos del programa de cálculo (ABAQUS, 2008), definiendo para los mismos un comportamiento mecánico del tipo ortótropo elástoplástico (Holmberg et al, 1999), con las constantes mecánicas indicadas antes en el apartado de materiales. Se aplicaron condiciones de simetría estudiándose gracias a ello únicamente la cuarta parte del modelo total.…”

Section: Modelo De Elementos Finitosunclassified

Rendimiento de Uniones Clavija de Tipo Perno Encolado usando Elementos Finitos

2011

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ResumenSe presenta un estudio sobre las tecnologías de unión en nudos de estructuras de madera, centrándose sobre todo en aquellas de tipo perno encolado. Se buscó comparar el rendimiento de estas uniones con las de tipo clavija sin encolar y se compararon los resultados obtenidos por tres métodos: i) aplicando las ecuaciones analíticas contempladas en las normas oficiales y la literatura; ii) realizando estudios mediante el método de los elementos finitos; iii) y realizando ensayos de laboratorio de estos mismos diseños propuestos. Para realizar el estudio por el método de los elementos finitos, se prepararon varios modelos paramétricos que permitieron englobar todas las variaciones posibles de las variables que afectan a la unión. Los resultados permitieron determinar como la modificación de las variables estudiadas afectan al rendimiento en cada caso. Palabras clave: uniones, estructuras de madera, pernos encolados, elementos finitos Performance of Dowel-Type Joints of the Glued in Rod Type using Finite ElementsA study on wood-steel joints used in timber structures with emphasis on the, glued in rod type, is presented. The performance of these joints with and without adhesive where compared and the results from these studies were analyzed in three different ways; i) using the analytical equations applied in the official standards and in the literature; ii) using the finite element method technique; and iii) making empiric tests of the same proposed designs used in the two previous methodologies. To use the finite element method, different parametric models were prepared, which could include all the possible variations of the variables which affect the joint performance. The results allowed determining how the modification of the variables studied affects the performance in each case.

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Nonlinear mechanical behaviour and analysis of wood and fibre materials

Cited by 108 publications

References 8 publications

<b>Shear and longitudinal modulus of elasticity in wood: relations based on static bending tests

<b>Shear and longitudinal modulus of elasticity in wood: relations based on static bending tests

Variation of measured cross-sectional cell dimensions and calculated water vapor permeability across a single growth ring of spruce wood

Rendimiento de Uniones Clavija de Tipo Perno Encolado usando Elementos Finitos

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