Analysis of Wood Laminated Beams Reinforced with Sisal Fibres

2014 ◽  
Vol 600 ◽  
pp. 97-104 ◽  
Author(s):  
Nilson Tadeu Mascia ◽  
Raul Martini Mayer ◽  
Reinaldo Washington Moraes
Keyword(s):  
Natural Fibres ◽  
Shear Stresses ◽  
Structural Elements ◽  
Laminated Beams ◽  
Sisal Fibre ◽  
Section Method ◽  
Classical Lamination Theory ◽  
Lamination Theory ◽  
Laminated Structures ◽  
Normal And Shear Stresses

Natural fibres have recently raised attention for presenting adequate mechanical characteristics for the reinforcement of wood structural elements. The use of both natural fibres, in laminated beams and wood from reforestation, is in accordance with the current economic interest and sustainable appeal. This paper focuses on the analysis the viability of sisal fibre use, in wood laminated structures as a reinforcing material, taking three methods into consideration: Stress functions, Classical lamination theory and Transformed section method. The laminated beams were reinforced by sisal strips with a thickness of 2 mm and constituted by the species of wood: Pinus (Pinus sp). Each lamina has the following dimensions: width of 5 cm, height of 10 cm and length of 150 cm. It was noted that the differences between the results from the classical lamination theory and transformed section method were, in an average of 14 % and 16 % for normal and shear stresses respectively. The difference of 12 % for displacements is a normal result taking into account that the span used is considered high for this wood species. In relation to the stress function method, the differences are minimal, around less than 1% for all analyses. It was also noted that the beam with reinforcement presented a decrease of the values of normal and shear stresses and displacements in relation a beam without reinforcing fibres. This decrease was of the order of 8% for the normal and 5% for the shear stresses and 12 % for the displacements In general, the strengthening of wood laminated beams with sisal fibres is more effective for structures that are used only in wood structural elements, in which the elastic modulus is at least equal to these fibres.

Analysis of Wood Laminated Beams Reinforced by Natural Fibres

2013 ◽  
Vol 778 ◽  
pp. 553-560 ◽  
Author(s):  
Nilson Tadeu Mascia ◽  
Raul Martini Mayer
Keyword(s):  
Mechanical Characteristics ◽  
Natural Fibres ◽  
Shear Stresses ◽  
Structural Elements ◽  
Laminated Beams ◽  
Stress Functions ◽  
Lamination Theory ◽  
Reinforcing Material ◽  
Theoretical Results ◽  
Normal And Shear Stresses

This paper presents an analysis on the viability of the use of natural fibres, in particular sisal fibres, as a reinforcing material in wood laminate structures. The use of natural fibres associated to the manufacturing of beams, with wood from reforestation, is in accordance with the current economic interest and ecological appeal. Sisal fibres have attracted attention for presenting adequate mechanical characteristics for such application. The laminated beams used in this research were constituted byPinus spand were reinforced by sisal strips with a thickness of 2 mm glued by Epoxi adhesive on bottom of the beam on the tensile region. Each lamina had the following dimensions: width of 50 mm, height of 20 mm and the length of the beam is 1.5 m. For the theoretical analysis of wood laminate beams three models: stress functions, classical lamination theory and section transformed method are carried out. It was noted that the average differences between the theoretical results and experimental data are given by: 11% and 2 % for normal and shear stresses respectively, and around 8%, for displacements. As a conclusion, the strengthening of wood laminate beams with sisal fibres is effective in wood structural elements, in which the elastic modulus is at maximum equal to these fibres and also prevents fragile failure on critical tensile region.

scholarly journals Insulation Characteristics of Sisal Fibre/Epoxy Composites

2017 ◽  
Vol 2017 ◽  
pp. 1-6 ◽  
Author(s):  
A. Shalwan ◽  
M. Alajmi ◽  
A. Alajmi
Keyword(s):  
Volume Fraction ◽  
Fibre Volume Fraction ◽  
Thermal Characteristics ◽  
Fibre Volume ◽  
Point Of View ◽  
Natural Fibres ◽  
Epoxy Composites ◽  
Ongoing Research ◽  
Sisal Fibre ◽  
The Impact

Using natural fibres in civil engineering is the aim of many industrial and academics sectors to overcome the impact of synthetic fibres on environments. One of the potential applications of natural fibres composites is to be implemented in insulation components. Thermal behaviour of polymer composites based on natural fibres is recent ongoing research. In this article, thermal characteristics of sisal fibre reinforced epoxy composites are evaluated for treated and untreated fibres considering different volume fractions of 0–30%. The results revealed that the increase in the fibre volume fraction increased the insulation performance of the composites for both treated and untreated fibres. More than 200% insulation rate was achieved at the volume fraction of 20% of treated sisal fibres. Untreated fibres showed about 400% insulation rate; however, it is not recommended to use untreated fibres from mechanical point of view. The results indicated that there is potential of using the developed composites for insulation purposes.

An Experimental Investigation of the Yield Loci of 1100-0 Aluminum, 70:30 Brass, and an Overaged 2024 Aluminum Alloy After Various Prestrains

1986 ◽  
Vol 108 (4) ◽  
pp. 313-320 ◽  
Author(s):  
D. E. Helling ◽  
A. K. Miller ◽  
M. G. Stout
Keyword(s):  
Aluminum Alloy ◽  
Small Strain ◽  
Yield Locus ◽  
Material Behavior ◽  
Shear Stresses ◽  
2024 Aluminum Alloy ◽  
Yield Loci ◽  
Aluminum Alloy 2024 ◽  
Von Mises ◽  
Normal And Shear Stresses

The multiaxial yield behaviors of 1100-0 aluminum, 70:30 brass, and an overaged 2024 aluminum alloy (2024-T7) have been investigated for a variety of prestress histories involving combinations of normal and shear stresses. Von Mises effective prestrains were in the range of 1.2–32%. Prestress paths were chosen in order to investigate the roles of prestress and prestrain direction on the nature of small-strain offset (ε = 5 × 10−6) yield loci. Particular attention was paid to the directionality, i.e., translation and distortion, of the yield locus. A key result, which was observed in all three materials, was that the final direction of the prestrain path strongly influences the distortions of the yield loci. Differences in the yield locus behavior of the three materials were also observed: brass and the 2024-T7 alloy showed more severe distortions of the yield locus and a longer memory of their entire prestrain history than the 1100-0 aluminum. In addition, more “kinematic” translation of the subsequent yield loci was observed in brass and 2024-T7 than in 1100-0 aluminum. The 2024-T7 differed from the other materials, showing a yield locus which decreased in size subsequent to plastic straining. Finally, the implications of these observations for the constitutive modeling of multiaxial material behavior are discussed.

Computer analysis of thin-walled concrete box beams

1989 ◽  
Vol 16 (6) ◽  
pp. 902-909 ◽  
Author(s):  
Shahbaz Mavaddat ◽  
M. Saeed Mirza
Keyword(s):  
Key Words ◽  
Computer Analysis ◽  
Shear Stresses ◽  
Shear Lag ◽  
Applied Loading ◽  
Box Beam ◽  
Box Beams ◽  
Three Stages ◽  
Thin Walled ◽  
Normal And Shear Stresses

Three computer programs, written in FORTRAN WATFIV, are developed to analyze straight, monolithically cast, symmetric concrete box beams with one, two, or three cells and side cantilevers over a simple span or over two spans with symmetric mid-span loadings. The analysis, based on Maisel's formulation, is performed in three stages. First, the structure is idealized as a beam and the normal and shear stresses are calculated using the simple bending theory and St-Venant's theory of torsion. The secondary stresses arising from torsional and distortional warping and shear lag are calculated in the second and third stages, respectively. The execution times on an AMDAHL 580 system are 0.02, 0.93, and 0.25 s for the three programs, respectively. The stresses arising in each stage of analysis are then superposed to determine the overall response of the box section to the applied loading. The results are compared with Maisel's hand calculations. Key words: bending, bimoment, box beam, computer analysis, FORTRAN, shear, shear lag, thin-walled section, torsion, torsional and distortional warping.

Measurements in a Turbulent Boundary Layer Over a d-Type Surface Roughness

1975 ◽  
Vol 42 (3) ◽  
pp. 591-597 ◽  
Author(s):  
D. H. Wood ◽  
R. A. Antonia
Keyword(s):  
Boundary Layer ◽  
Surface Roughness ◽  
Turbulent Boundary Layer ◽  
Turbulent Energy ◽  
Shear Stresses ◽  
Normal Velocity ◽  
Mean Velocity ◽  
Outer Flow ◽  
Intensity Measurements ◽  
Normal And Shear Stresses

Mean velocity and turbulence intensity measurements have been made in a fully developed turbulent boundary layer over a d-type surface roughness. This roughness is characterised by regular two-dimensional elements of square cross section placed one element width apart, with the cavity flow between elements being essentially isolated from the outer flow. The measurements show that this boundary layer closely satisfies the requirement of exact self-preservation. Distribution across the layer of Reynolds normal and shear stresses are closely similar to those found over a smooth surface except for the region immediately above the grooves. This similarity extends to distributions of third and fourth-order moments of longitudinal and normal velocity fluctuations and also to the distribution of turbulent energy dissipation. The present results are compared with those obtained for a k-type or sand grained roughness.

Additive manufactured multi-material structure with directional specific mechanical properties based upon classical lamination theory

2018 ◽  
Vol 24 (7) ◽  
pp. 1212-1220 ◽  
Author(s):  
Sugavaneswaran M. ◽  
Arumaikkannu G.
Keyword(s):  
Mechanical Properties ◽  
Three Dimensional ◽  
Additive Manufacture ◽  
Material Structure ◽  
Loading Conditions ◽  
Content Type ◽  
Three Dimensional Printing ◽  
Classical Lamination Theory ◽  
Innovative Methodology ◽  
Lamination Theory

Purpose This paper aims to additive manufacture (AM) the multi-material (MM) structure with directional-specific mechanical properties based on the classical lamination theory of composite materials. Design/methodology/approach The polyjet three-dimensional printing (3DP) process is used to fabricate the MM structure with directional-specific mechanical properties. MMs within a layer are positioned and oriented based on the classical lamination theory to achieve directional-specific properties. Mechanical behavior of the AM structure was examined under various loading conditions to justify the directional-specific properties. Findings With MM processing capabilities of the polyjet 3DP machine, AM MM structures with directional-specific mechanical properties were fabricated. From experimentation, it was observed that the AM MM structure with a quasi-isotropic laminate has superior tensile and flexural strength, and the AM MM structure with an angle ply laminate has superior shear strength. Various mechanical properties determined through testing will be useful for the selection of an appropriate layup arrangement within a structure for appropriate loading conditions. Originality/value This study presents the innovative methodology for the fabrication of AM MM structures with tailor-made mechanical properties. The developed methodology paves way for using the polyjet 3DP MM structure for applications such as the complaint mechanism, snap fits and thin features, which require directional-specific properties.

scholarly journals Influence of Material Ductility on Fatigue Life under Multiaxial Proportional and Non-Proportional Normal and Shear Stresses

2019 ◽  
Vol 300 ◽  
pp. 17001 ◽  
Author(s):  
Cetin Morris Sonsino
Keyword(s):  
Fatigue Life ◽  
Tensile Elongation ◽  
Shear Stresses ◽  
Normal Strain ◽  
Proportional Loading ◽  
Ductile Materials ◽  
Critical Components ◽  
Material Ductility ◽  
Fatigue Life Reduction ◽  
Normal And Shear Stresses

Current experiences show that a non-proportional loading of ductile materials such as wrought steels, wrought aluminium or magnesium alloys, not welded or welded, causes a significant fatigue life reduction under an out-of-phase shear strain or shear stress superimposed on a normal strain or normal stress compared with proportional in-phase loading. However, when ductility, here characterised by tensile elongation, is reduced by a heat treatment or by another manufacturing technology such as casting or sintering, the afore-mentioned life reduction is compensated or even inversed, i. e. longer fatigue life results compared with proportional loading. Some actual results, determined with additive manufactured titanium, suggest that microstructural features such as manufacturing-dependent internal defects like microporosities should be considered in addition to the ductility level. This complex life behaviour under non-proportional loading cannot always be estimated. Therefore, in experimental proofs of multiaxial loaded parts, especially safety-critical components or structures, with real or service-like signals, emphasis must be placed on retaining non-proportionalities between loads and stresses/strains, respectively.

scholarly journals Extraction of Dyes from Petrocarpus santalinus and Dyeing of Natural Fibres Using Different Mordants

2018 ◽  
Vol 26 (5(131)) ◽  
pp. 20-23
Author(s):  
Ramaiah Mariselvam ◽  
Ganesan Athinarayanan ◽  
Amirtham J. A. Ranjitsingh ◽  
Ayyakannu Usha Raja Nanthini ◽  
Rajapandiyan Krishnamoorthy ◽  
...  
Keyword(s):  
Oxalic Acid ◽  
Stannous Chloride ◽  
Natural Fibres ◽  
Ferrous Ammonium Sulphate ◽  
Tamarindus Indica ◽  
Sisal Fibre ◽  
Banana Fibre ◽  
Tin Metal ◽  
Ferrous Ammonium ◽  
Palm Leaf

Aqueous extraction of natural dyes from Petrocarpus santalinus tree wood and dyeing of the following natural fibres: banana fibre, screw fine fibre, pineapple fibre, sisal fibre, korai and palm leaf using various mordants to fix the colour in the fibre materials were performed. Salt, sodium bicarbonate, oxalic acid, tannic acid, ferrous ammonium sulphate, stannous chloride (tin metal powder), alum and tamarind (Tamarindus indica) were used as a mordant for the dying of the natural fibres. Petrocarpus santalinus dye was effectively dyed on natural fibres using different mordants, producing different colours like tomato, maroon, orange red, chocolate, brown, quarry red, black, brick red, tile red, terra colla, sunbaked clay, gray, brick red, victorian red, firebrick, brown, crimson and orange, using these mordants.

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