Academic literature on the topic 'Compression parallel to grain tests'

O objetivo deste estudo foi analisar o efeito da posição do colmo e da idade nas propriedades mecânicas de flexão estática e compressão paralela às fibras do bambu-mossô (Phyllostachys pubescens), correlacionando a densidade aparente com as propriedades avaliadas. Os corpos de prova utilizados nos ensaios foram produzidos de material laminado colado, adaptados segundo a norma para madeira sólida ASTM D143-96, seguindo as proporções mantidas por Ahmad (2000). Os resultados apresentaram tendência crescente da resistência na flexão estática com a idade e com a posição do colmo em termos absolutos. Para os ensaios de compressão paralela às fibras, a resistência à compressão (fc) e o MOE tiveram a mesma tendência de aumento da resistência com a idade e com a posição. Os ensaios demonstraram estatisticamente que não houve efeito significativo da interação entre a idade e a posição do colmo. A densidade aparente apresentou uma correlação linear e positiva no teste de flexão estática quanto aos valores do MOR e do MOE, assim como no teste de compressão paralela às fibras para a resistência à compressão (fc) e para o MOE. Baixos coeficientes de correlação foram obtidos entre a densidade aparente e as propriedades mecânicas estudadas.AbstractCompressive strength and flexure of Moso bamboo (Phyllostachys pubescens). The aim of this study was to determine the mechanical properties of bending and compression parallel to grain of Moso bamboo (Phyllostachys pubescens) and analyze the effect of stem position and age on these properties. It was also studied the correlation between the bulk density and mechanical properties. The tests used specimens produced in glued laminated material, adapted according to ASTM D143 solid wood-96 norm, following proportions maintained by Ahmad (2000). The results revealed increasing trend of resistance in bending with age and stem position in absolute terms. In relation to compression tests parallel to grain, the compression strength (fc) and the MOE had the same tendency to increase resistance with age and with the position. The tests revealed that there was no statistically significant interaction between age and culm position. The apparent density of bamboo revealed a positive and linear correlation in bending test at MOR and MOE, as well as at parallel compression test to the fibers for the compression force (fc) and the MOE. Low correlation coefficients had been obtained between the focused apparent density and mechanical properties.Keywords: Mechanical properties; age; position of the culm.

Abstract This paper describes methods developed to test the mechanical properties of small-diameter (3–10 mm) 1-year-old trees. Special test fixtures and procedures were designed to accommodate the small diameter and uneven shape of these young trees. The modulus of elasticity and strength in tension parallel to the grain, compression parallel to the grain, and bending were measured.

This paper presents the results obtained in a series of tests on Pinus Pinaster Ait. timber specimens, using the prEN408:2000, to estimate the local and global Young’s modulus and strength both in bending and compression parallel to the grain. The results obtained are compared with the values presented in the Portuguese Nationally Determined Parameters of Eurocode 5, for the quality classes assign by Portuguese Standard NP4305:1994 by visual grading.

AbstractSoftwood is commonly used in timber structures, whose dynamic compressive properties along the grain direction under seismic rate actions are of major concern. In the present study, 108 samples were examined from three species of softwoods (spruce, Dahurian larch and pine) and subjected to four levels of strain rates (10−4 s−1, 10−3 s−1, 10−2 s−1 and 0.1 s−1) under parallel-to-grain monotonic and repeated compression. The seismic strain rate effects on softwood were investigated by observing the failure mechanisms, engineering stress-strain curves, initial crushing strength, elastic modulus and peak strain. Results demonstrated the high sensitivity of softwood to seismic strain rates. Finally, a rate-dependent constitutive model was developed to predict the stress-strain relationship (both monotonic and repeated loading cases) of softwood under different seismic strain rates.

The tests used to obtain the stiffness properties of wood are made with two loading cycles, as defined by the Brazilian standard ABNT NBR 7190 (Design of Timber Structures). However, the possibility of reducing the number of cycles allows decrease the operating time of the machine, resulting in reduced spending on electricity used during the tests. This research aimed to investigate, with the aid of the analysis of variance (ANOVA), the influence of the use of three load cycles to obtain the modulus of elasticity in compression parallel to grain (Ec0), in tensile parallel to the grain (Et0), in bending (Em) and in compression perpendicular to the grain (Ec90) of Angico Preto (Anadenanthera macrocarpa) wood specie. For the number of cycles and stiffness were manufactured 12 samples, totaling 144 specimens. The results of the ANOVA revealed statistical equivalence between the stiffness properties for both load cycle numbers evaluated, indicating that it is possible to carry out the tests with a single charge cycle, allowing savings in time and energy in the operation of the equipment.

Effect of microstructure on micro-cracking behavior of Al-Mg-Si alloy extrusions during axial compressive deformation was studied. Extrusions of Al-Mg-Si alloys with two different compositions were used for the mechanical tests and microstructure observation. Compressive loads were applied parallel to the axes of the tubular specimens with rectangular cross section. As deformation proceeded, the specimens changed their shape into bellows-like ones. Specimens with finer grains showed higher critical strength and strain for crack initiation. Microscopic observation showed that cracks initiated at the bulge surface of the bellows and propagated into the depth. The observed behavior of crack initiation and propagation was interpreted in connection with those in simple tensile tests. The stress and strain at the crack initiation site of the bulge were assumed to correspond to the tensile strength of the alloy. The effect of grain size on the crack behavior was well explained by the grain size dependence of stress concentration at grain boundaries due to dislocation pile-ups. The effects of over-aging on the microstructure and crack initiation behavior were also discussed.

Wood behaves differently in three independent orthotropic directions, namely radial, tangential and longitudinal. Determination of mechanical properties of wood and the study on the orthotropic behavior could enhance effective utilization of wood as construction material. Kapur and Kelat are two commercial medium hardwoods that are found abundantly in the east-coast of Malaysia. The purpose of the study is to determine the variation of bending and compression strength properties of Kapur and Kelat in three different anatomical directions. Bending and compression tests on small clear specimens were carried out according to BS373:1987. The result shows that Kapur is higher in bending and compression strength compares to Kelat. Bending strength properties for Kapur and Kelat were found to be significantly higher on the radial direction compared to tangential direction. In compression, the strength properties are higher on the longitudinal directions that are parallel to the grain. This is followed by radial and tangential direction for both Kapur and Kelat. The result also shows that compression strength parallel to the grain for both wood species to be significantly different from those perpendiculars to the grain.

The natural variation of some strength properties of about 80‑year old brown‑and green‑pigmented San Ramon variety of coconut was investigated. The properties were determined from tests on small clear specimens in the air dry condition with an average moisture content of 16.98%. The mechanical properties studied include modulus of rupture, stress at elastic limit and modulus of elasticity in static bending, maximum crushing strength in compression parallel to grain, stress at elastic limit and in compression perpendicular to grain, and shear parallel to grain.
 
 The brown‑pigmented trees showed significantly higher values in all the mechanical properties than the green‑pigmented palms.
 
 For the brown‑and green‑pigmented trees, the values of strength properties markedly decreased with increasing height levels and significantly increased radially from the core to the periphery of the stem.

In the context of global sustainable development, the use of natural and renewable bamboo as a building material is of great significance for building engineering. As an important part of bamboo, there is still a lack of systematic research on the effect of bamboo nodes on the mechanical properties of bamboo. In this paper, compression parallel to the grain of the bamboo, bending, tensile parallel to the grain, shear parallel to the grain, compression perpendicular to the grain and tensile perpendicular to the grain tests of an entire bamboo culm of P. edulis bamboo were carried out, and the effects of bamboo nodes on moisture content, bearing capacity and mechanical properties were analyzed. The relationship between the mechanical properties and standardized parameters of the node and internode specimens was established. A conversion method of mechanical properties of the same test type was proposed, and a conversion method among different mechanical properties was proposed. The bamboo was graded by tensile strength parallel to the grain. The results show that bamboo nodes have an obvious effect on the moisture content. Bamboo nodes have different effects on the bearing capacity and mechanical properties of different types of specimens. The mechanical properties of P. edulis bamboo can be predicted by the relationship between the mechanical properties and the standardized parameters and the mechanical property conversion method. The strength classification of P. edulis bamboo can be predicted by standardized parameters.

Strength properties’ tests are conducted in the small clear sample. This paper aim to acquire the basic and grade stresses of some fast growing species thus identifies its strength group. Thus, the information of wood properties from different species and condition are acquired from strength property's test. The required information namely, bending parallel to the grain, compression stress parallel to grain, shear parallel to grain and modulus of elasticity. The condition of the trees which is referred to green and air-dry condition. Three different species which are referred to exotic species of Acacia mangium and indigenous species of Aras. The results from the study indicated that, Acacia mangium classified under the strength group SG5, whilst Aras was classified under the strength group SG7. The timber is of medium density Light Hardwood ranging from 0.37-0.52g/cm3 air-dry condition.