scholarly journals Estimating Dependence Among Lumber Strength Properties With Copula Models

2021 ◽  
Vol 6 ◽  
Author(s):  
Yanling Cai ◽  
Harry Joe ◽  
Shenyi Pan
Keyword(s):  
Graphical Method ◽  
Strong Dependence ◽  
Simulated Data ◽  
Strength Properties ◽  
Modulus Of Rupture ◽  
Copula Model ◽  
Lumber Industry ◽  
Copula Models ◽  
Dependence Modeling ◽  
Loading Procedure

A copula-based approach is used to estimate the dependence among three lumber strength properties: modulus of elasticity (MOE), modulus of rupture (MOR), and ultimate tensile strength (UTS). MOR and UTS are destructive measurements so they cannot be obtained simultaneously for lumber specimens. The dependence modeling is possible under an appropriate experimental design with i) a shoulder group for rupture, ii) a shoulder group for tension, and iii) other groups proof loaded in either the rupture or tension mode with survivors tested to failure in the mode that was not initially tested. With a fitted copula model based on an assumption of no damage due to the proof loading procedure, we conclude that there is a strong dependence between MOR and UTS conditioning on MOE. To assess the “no damage assumption,” a graphical method with simulated data from the fitted copula model is used. It suggests that there may be some damage to the lumber specimens due to proof loading, especially for weaker lumber specimens. Information from the dependence model can potentially help reduce monitoring costs in the lumber industry.

scholarly journals Improved strength properties of LVL glued using PVAc adhesives with physical treatment-based Rubberwood (Hevea brasiliensis)

2020 ◽  
Vol 5 (1) ◽  
pp. 711-725
Author(s):  
Sutrisno ◽  
Eka Mulya Alamsyah ◽  
Ginanjar Gumilar ◽  
Takashi Tanaka ◽  
Masaaki Yamada
Keyword(s):  
Shear Strength ◽  
Hevea Brasiliensis ◽  
Formaldehyde Emission ◽  
Strength Properties ◽  
Modulus Of Rupture ◽  
Horizontal Shear ◽  
Physical Treatment ◽  
Cold Pressing ◽  
Laminated Veneer Lumber ◽  
Pressing Time

AbstractThe properties of the laminated veneer lumber (LVL) composed of the boiled veneer of Rubberwood (Hevea brasiliensis) using polyvinyl acetate (PVAc) adhesives in various cold-pressing time and various conditioned time with loaded and unloaded were studied. Five-ply LVL was produced by boiling veneer at 100°C for 90 min as pretreatment and cold-pressing time at 12 kgf cm−2 for 1.5, 6, 18, and 24 h then conditioned at 20°C and 65% relative humidity (RH) with loaded (12 kgf cm−2) and unloaded for 7 days as physical treatment. Especially for the delamination test, the specimens were immersed at 70 ± 3°C for 2 h and dried in the oven at 60 ± 3°C for 24 h; then, the specimens were solidified at room temperature (20°C and 65% RH) with loaded (12 kgf cm−2) and unloaded for 7, 10, 12, and 14 days. To determine the performance of LVL, the density, moisture content (MC), delamination, modulus of elasticity (MOE), modulus of rupture (MOR), horizontal shear strength, and formaldehyde emission tests were conducted according to the Japanese Agricultural Standard (JAS 2008) for structural LVL. The MOE and MOR values were significantly influenced by the physical treatment, however, neither to horizontal shear strength nor to formaldehyde emission. The best performance of LVL has resulted from unloaded LVL with cold-pressed time for 18 h; the MOE and MOR values were 9,345.05 ± 141.61 N mm−2 and 80.67 ± 1.77 N mm−2, respectively. The best value of the horizontal shear strength was obtained from the LVL with 18 h cold-pressing time and conditioned with loaded (13.10 ± 1.47 N mm−2) and unloaded (12.23 ± 1.36 N mm−2). The percentage of delamination values decreased with an increase in the cold-pressing time and conditioning time. The lowest value of delamination (19.06%) was obtained from the LVL with 24 h cold-pressing time and conditioned with loaded for 14 days. Except the delamination test, all other properties fulfilled the JAS.

scholarly journals Sixteen properties of Eucalyptus Tereticornis wood for structural uses

2020 ◽  
Vol 36 (2) ◽  
Author(s):  
Marta Cristina de Jesus Albuquerque Nogueira ◽  
Victor Almeida de Araujo ◽  
Juliano Souza Vasconcelos ◽  
André Luis Christoforo ◽  
Francisco Antonio Rocco Lahr
Keyword(s):  
Mechanical Properties ◽  
Decision Making ◽  
Shear Stress ◽  
Modulus Of Elasticity ◽  
Strength Properties ◽  
Modulus Of Rupture ◽  
Eucalyptus Tereticornis ◽  
Moisture Contents ◽  
Through Diffusion ◽  
Standard Documents

Forest Red Gum eucalypt provides a versatile wood and is converted into different purposes. However, such wood is somewhat limited in structural ends, which highlights the need to exploit this gap through diffusion of mechanical properties of such timber. Obtained results should assist engineers and architects in decision-making for its best building application. This paper studied two physical and fourteen mechanical properties evaluation of Eucalyptus tereticornis at two different moisture contents, following the prescriptions of Brazilian (ABNT NBR 7190: 1997) and North American (ASTM D-143-14: 2014) standard documents. Thus, 1091 repeats were carried out for all properties. By a moisture reduction from 30% to 12%, the bulk density and eleven strength properties statistically showed changes such as modulus of rupture (static bending, parallel and perpendicular compressions), modulus of elasticity (perpendicular compression and static bending), shear stress, tangential cleavage, and parallel and perpendicular hardnesses. Then, the Eucalyptus tereticornis timber could be better usable if is further applied for structural construction uses.

Forecasting multivariate VaR and ES using MC-GARCH-Copula model

2020 ◽  
Vol 21 (5) ◽  
pp. 493-516 ◽  
Author(s):  
Hemant Kumar Badaye ◽  
Jason Narsoo
Keyword(s):  
Value At Risk ◽  
Garch Model ◽  
Dependence Structure ◽  
Copula Model ◽  
Copula Models ◽  
Content Type ◽  
Significance Level ◽  
Foreign Currencies ◽  
Out Of Sample ◽  
Weighted Portfolio

Purpose This study aims to use a novel methodology to investigate the performance of several multivariate value at risk (VaR) and expected shortfall (ES) models implemented to assess the risk of an equally weighted portfolio consisting of high-frequency (1-min) observations for five foreign currencies, namely, EUR/USD, GBP/USD, EUR/JPY, USD/JPY and GBP/JPY. Design/methodology/approach By applying the multiplicative component generalised autoregressive conditional heteroskedasticity (MC-GARCH) model on each return series and by modelling the dependence structure using copulas, the 95 per cent intraday portfolio VaR and ES are forecasted for an out-of-sample set using Monte Carlo simulation. Findings In terms of VaR forecasting performance, the backtesting results indicated that four out of the five models implemented could not be rejected at 5 per cent level of significance. However, when the models were further evaluated for their ES forecasting power, only the Student’s t and Clayton models could not be rejected. The fact that some ES models were rejected at 5 per cent significance level highlights the importance of selecting an appropriate copula model for the dependence structure. Originality/value To the best of the authors’ knowledge, this is the first study to use the MC-GARCH and copula models to forecast, for the next 1 min, the VaR and ES of an equally weighted portfolio of foreign currencies. It is also the first study to analyse the performance of the MC-GARCH model under seven distributional assumptions for the innovation term.

Estimation of Wood Stiffness and Strength Properties of Hybrid Larch by Near-Infrared Spectroscopy

2007 ◽  
Vol 61 (8) ◽  
pp. 882-888 ◽  
Author(s):  
Takaaki Fujimoto ◽  
Hiroyuki Yamamoto ◽  
Satoru Tsuchikawa
Keyword(s):  
Near Infrared ◽  
Nir Spectroscopy ◽  
Strength Properties ◽  
Density Variation ◽  
Modulus Of Rupture ◽  
Cellulose Content ◽  
Hybrid Larch ◽  
Absorption Bands ◽  
Wood Stiffness ◽  
Predicted Values

This work was undertaken to investigate the feasibility of near-infrared (NIR) spectroscopy for estimating wood mechanical properties, i.e., modulus of elasticity (MOE) and modulus of rupture (MOR) in bending tests. Two sample sets having large and limited density variation were prepared to examine the effects of wood density on estimation of MOE and MOR by the NIR technique. Partial least squares (PLS) analysis was employed and it was found that the relationships between laboratory-measured and NIR-predicted values were good in the case of sample sets having large density variation. MOE could be estimated even when density variation in the sample set was limited. It was concluded that absorption bands due to the OH group in the semi-crystalline or crystalline regions of cellulose strongly influenced the calibrations for bending stiffness of hybrid larch. This was also suggested from the result that both α-cellulose content and cellulose crystallinity showed moderate positive correlation to wood stiffness.

Mathematical models and experimental data for HDF based sandwich panels with dual corrugated lightweight core

Holzforschung ◽  
2017 ◽  
Vol 71 (3) ◽  
pp. 265-273 ◽  
Author(s):  
Jerzy Smardzewski ◽  
Dorota Jasińska
Keyword(s):  
Homogeneous Model ◽  
Sandwich Panels ◽  
Experimental Tests ◽  
Strength Properties ◽  
Modulus Of Rupture ◽  
Experimental Investigations ◽  
Calculation Results ◽  
Orthotropic Properties ◽  
Auxetic Structure ◽  
Lightweight Core

Abstract Light layer honeycomb panels could replace traditional wood materials, if their stiffness and strength properties could be improved. The aim of this research was to design and determine elastic properties of sandwich panels (SPs) based on a dual corrugated HDF core. Stiffness matrix values of elements were determined by a numerical method. The 3D calculation results were compared with those of the homogeneous model. The calculation results were collated with those of experimental investigations. It was demonstrated that the linear elasticity modulus as well as the modulus of rupture of the SPs were comparable with mechanical properties of a particle board with identical thickness, while the SP has a 1/3 lower density. The panel core exhibited significant orthotropic properties. In the xy plane it could be characterized as an auxetic structure. The homogeneous model leads to results similar to those achieved from the 3D model and observed in experimental tests.

Mechanical Property Evaluation of Electroplated High Aspect Ratio Microstructures

1998 ◽  
Vol 518 ◽  
Author(s):  
L. S. Stephens ◽  
K.W. Kelly ◽  
E.I. Meletis ◽  
S. Simhadri
Keyword(s):  
Mechanical Properties ◽  
Aspect Ratio ◽  
High Aspect Ratio ◽  
Mold Insert ◽  
Processing Parameters ◽  
Strength Properties ◽  
Knoop Hardness ◽  
Modulus Of Rupture ◽  
Mechanical Seal ◽  
Property Evaluation

AbstractHigh aspect ratio microstructures (HARMs) with a height of hundreds of micrometers and a width of a few tens of micrometers present high promise in a number of challenging fields. At LSU, a number of applications are being developed in which nickel HARMs are electroplated on metal surfaces (mold insert fabrication for the LIGA process, HARMs on mechanical seal faces, HARMs on heat exchange surfaces, etc.). In some of these applications, the HARMs are subjected to high stresses and the mechanical properties are particularly important. These properties can be used to adjust processing parameters to optimize properties of the HARMS.This paper presents a method for measuring the strength properties of cantilevered nickel HARMs constructed by LIGA. Experimentally measured values are reported for modulus of rupture (1280 MPa), Young's modulus (153 GPa) and Knoop hardness (500 Hk) for HARMs with an overplated base. SEM micrographs clearly indicate that failure of the beams is brittle and most frequently occurs at the interface of the beam and overplated base.

Effect of juvenile wood on strength properties and dimensional stability of black spruce medium-density fiberboard panels

Holzforschung ◽  
2005 ◽  
Vol 59 (1) ◽  
pp. 1-9 ◽  
Author(s):  
Jun Li Shi ◽  
Shu Yin Zhang ◽  
Bernard Riedl
Keyword(s):  
Water Absorption ◽  
Dimensional Stability ◽  
Juvenile Wood ◽  
Black Spruce ◽  
Medium Density Fiberboard ◽  
Strength Properties ◽  
Analysis Of Covariance ◽  
Modulus Of Rupture ◽  
Medium Density ◽  
Mean Values

Abstract Strength properties and dimensional stability of medium-density fiberboard (MDF) panels made from black spruce (Picea mariana [Mill.] BSP.) 0–20, 21–40, and over 40 year old fiber were studied. An analysis of covariance (ANCOVA) was performed to examine the differences in modulus of rupture (MOR), modulus of elasticity (MOE), and thickness swell (TS) of the three types of panels, while panel density was treated as a covariate in order to adjust the mean values that were partly attributed to panel density. The results indicate that MOR, internal bond (IB), and water absorption of MDF panels made from 0–20 year old fiber, which contained 100% juvenile wood, were significantly superior to those of panels made from 21–40 and over 40 year old fiber; but linear expansion (LE) of MDF panels made from 0–20 year old fiber was significantly larger than that of panels from the other two age classes. The differences in MOR, IB, water absorption, and LE between panels made from 21–40 and over 40 year old fiber were not significant. The comparisons of panel MOE and TS were relatively dependent on panel density due to existence of interactions among the three age groups.

scholarly journals Assessment of “Musa spp” Fibre Inclusion on the Strength and Sorption Properties of Cement Bonded Particle Board

2021 ◽  
Vol 1 (1) ◽  
pp. 1-11
Author(s):  
Jacob Mayowa Owoyemi ◽  
Hazzan Adigun
Keyword(s):  
Physical And Mechanical Properties ◽  
Strength Properties ◽  
Solid Wood ◽  
Sorption Properties ◽  
Modulus Of Rupture ◽  
Mixing Ratio ◽  
Particle Board ◽  
Mean Values ◽  
Musa Spp ◽  
Banana Fibre

The increase in demand for wood for various purposes has put serious pressure on Nigeria’s forest with its attendant fall in the supply of solid wood for construction purposes. As an alternative, non-woody material like banana stem fibre is being investigated for the production of Cement Bonded Particle Board (CBPB). The sorption and strength properties of CBPB from Musa spp fibre were assessed. The board samples were formed using cement to materials mixing ration of 2:1 and 3:1 and blending proportions of sawdust and banana fibre using ordinary Portland cement as a binder. Physical and Mechanical properties of boards produced from stem using were investigated. The influence of blending proportion (B.P) and mixing ratio (MR) on Density, Water Absorption (WA), Thickness Swelling (TS), Linear Expansion, Modulus of Rupture (MOR), and Modulus of Elasticity (MOE) were determined. The results of sorption properties showed that for immersion at 24, 48, and 72 hours, WA, TS, and LE decreased with an increase in mixing ratio. MOE mean values ranged between 293.65 and 2367.01 N/mm2 for 2:1 and 250.99 and 2009.28 N/mm2 for 3:1 while MOR values ranged between 2.55 and 7.592 N/mm2 for 2:1 and ranged from 0.55 to 1.40 N/mm2 for 3:1 respectively. The result proved that banana fibre is suitable for the production of panel products with enhanced strength properties.

scholarly journals VARIABILITY OF SOME MECHANICAL PROPERTIES OF SAN RAMON TALL VARIETY OF COCONUT

CORD ◽  
1994 ◽  
Vol 10 (01) ◽  
pp. 34
Author(s):  
R. N. Palomar
Keyword(s):  
Mechanical Properties ◽  
Natural Variation ◽  
Elastic Limit ◽  
Strength Properties ◽  
Modulus Of Rupture ◽  
Average Moisture Content ◽  
Rupture Stress ◽  
Crushing Strength ◽  
The Core ◽  
Strength In Compression

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.

scholarly journals KUALITAS PAPAN KOMPOSIT YANG TERBUAT DARI LIMBAH KAYU SENGON DAN KARTON DAUR ULANG

PERENNIAL ◽  
2006 ◽  
Vol 2 (1) ◽  
pp. 6 ◽  
Author(s):  
. Suhasman ◽  
Muh. Yusram Massijaya ◽  
Yusuf Sudo Hadi
Keyword(s):  
Bending Strength ◽  
Dry Weight ◽  
Strength Properties ◽  
Solid Content ◽  
Modulus Of Rupture ◽  
Composite Board ◽  
Resin Solid ◽  
Japanese Industrial Standard ◽  
Board Type ◽  
Materials Used

The use of recycled carton as an alternative material for the layer of composite board may increase the board strength properties. The objective of this research was to find out the influence of face and back layer types on the quality of produced boards. Materials used in this study were wafer made from sengon wood (Paraserianthes falcataria L. Nielsen), water based polymer isocyanate adhesive, and several kinds of cartons such as duplex carton, recycled carton, and waste of corrugated board. The composite board was produced with the target density of 0.65 g/cm3 and the resin solid content of 6% based on oven dry weight of particle, face and back layers. The results are as follows : 1) Utilization of carton layers improved the dimensional stability and bending strength of board; 2) Composite board with recycled carton layer fullfilled the Japanese Industrial Standard (JIS) A-5908-1994 for wafer board type in terms of density, water content, and modulus of rupture (MOR) in lengthwise and widhtwise of board but, did not fullfill that for veneered particled board type; 3) The presence of those layer material types decreased internal bond of the board. Keywords : composite board, face and back layer types, recyled carton

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