Dynamic MOE Research Articles

Effect of size variation of fibre-shaped waste tyre rubber as fine aggregate on the ductility of self-compacting concrete.

Abandoning shredded waste tyre rubber (WTR) in cement-based mixes facilitates safe waste tyre disposal and conserves the natural resources used in construction materials. The engineering properties of such environment-friendly materials needed to be evaluated for field applications. This study examined integrating WTR fibre on microstructural, static load, and ductility properties of self-compacting concrete (SCC). The WTR fibre of 0.60-1.18-, 1.18-2.36-, and 2.36-4.75-mm sizes was used as fine aggregate at 10%, 20%, and 30% replacement levels. Microstructural characterisation of hardened concrete specimens was done by scanning electron microscopy. The compressive strength and static modulus of elasticity tests were used to examine static load resistance, while drop weight and rebound impact tests were used to investigate impact load resistance. The water permeability test was performed as a measure of the durability of SCC with WTR fibre. Relationships have been studied between dynamic MOE and impact tests and rebound and drop weight impact testing. The Weibull two-parameter distribution was used to analyse the drop weight test statically. The results show that WTR fibre size variations efficiently lowered the concrete stiffness reducing the brittleness. Furthermore, incorporating WTR fibre improved the impact resistance of SCC.

Prediction of the mechanical properties of timber members in existing structures using the dynamic modulus of elasticity and visual grading parameters

The modulus of elasticity and bending strength of 45 structural Salzmann pine timber pieces with nominal dimensions of 150x200x5400 mm3 from an existing 18th century structure were estimated by semi-destructive density estimation probing method (drilling chips extraction) and acoustic wave velocity (stress and ultrasound wave). Bending strength, modulus of elasticity and density were obtained according to the EN 408 European standard, and visual grading singularities were recorded. Visual grading methods are highly ineffective for existing timber structures. Sample mechanical properties show a typical profile of material from existing structures, and this was compared with the results of similar works. MOE and MOR predictive models were proposed with determination coefficients r2 of 66–68% and 51–52%, respectively, using dynamic MOE, relative edge knot diameter and slope of grain as independent variables. MOR prediction improved when these grading parameters were included.

From Visual Grading and Dynamic Modulus of European Beech (Fagus sylvatica) Logs to Tensile Strength of Boards

The aim of the present paper is to assess the non-destructive indicating properties of Slovenian beech (Fagus sylvatica) logs and correlate them with the mechanical properties of the final product, which is boards. Beech logs were visually graded according to the standard procedure and vibrational frequencies were measured. Logs were further on sawn into boards which were also non-destructively tested in wet and dry conditions. Finally, the boards were experimentally tested in tension. Special focus was directed towards visual parameters of the beech logs and their influence on the overall quality of the output material. The longitudinal natural frequencies of the logs were studied as potential indicating properties. The results showed that a majority of the visual log grading parameters do not result in good quality timber in terms of strength and stiffness properties, and only few are decisive for the final classification. The coefficient of determination of the static MOE vs. dynamic MOE of logs was r2=0.13, whereas vs. the MOE of wet boards was r2=0.49. Using a few visual characteristics in combination with dynamic measurements of logs and of wet boards could help to increase the yield of high quality beech wood.

Strength and stiffness predictions with focus on different acoustic measurement methods

Strength grading is an important step for the production of homogenous and high-quality solid wood material. In particular, for hardwoods, the use of non-visible characteristics is indispensable. Dynamic MOE (Edyn) is an important parameter widely used for grading of softwoods and applicable to hardwoods as well. There are two common ways to measure Edyn—ultrasound (US) wave propagation and longitudinal vibration (LV) method. Both methods are used in practice, however, due to the different inherent measurement techniques, the results differ. The current paper analyses the stiffness and strength coefficients of determination for several temperate European hardwood species and emphasizes the differences between the two measurement systems. The performance was analysed with regard to grading techniques, testing modes for the mechanical properties (tension and bending) and wood qualities. For more than 2861 pieces of European ash (Fraxinus excelsior), European beech (Fagus sylvatica), European oak (Quercus spp.) and maple (Acer spp.), the Edyn was measured using both techniques, and destructive tests (tension and edgewise bending) were applied. The results show that LV has higher coefficient of determination compared to the US Edyn. The coefficient of determination for both methods and tensile application can be increased by calculating Edyn with average density. Furthermore, the results support species-independent strength grading of hardwoods. Further research on the effect of different wood qualities and sawing patterns is required.

Use of longitudinal vibration and visual characteristics to predict mechanical properties of No. S Southern pine 2x8 and 2x10 Lumber

The objective of this study was to evaluate the accuracy of single MOE and MOR and combined mechanical properties with visual characteristics to improve the prediction of 2 x 8 and 2 x 10 No. @ southern pine lumber. This study evaluated the following variables: nondestructive tests, knots (knot diameter ratio [KDR] and knot area ratio), density, and mechanical properties (stiffness [MOE] and strength [MOR]). A total of 486 pieces were used, and linear regression models were constructed using stepwise selects to determine the best variables to estimate the MOE and MOR of southern pine lumber. The best single predictor for MOE and MOR was dynamic MOE (dMOE) followed by density. Among the two knot measurement methods used, the KDR best predicted stiffness and strength. For predicting the MOE, the variables dMOE, density, and KDR. The results showed that the addition of knot measurements to the models is able to improve the prediction of mechanical properties.

Prediction of tensile strength of sawn timber: models for calculation of yield in strength classes

In Europe, strength classes for structural timber and glulam lamellae are defined by minimum requirements of characteristic values of the grade determining properties (GDPs). To fulfill these minimum requirements of characteristic values in the daily production at sawmills, indicating properties (IPs) to GDPs are calculated for each board and based on predetermined limits of the IPs (settings) boards are assigned to the graded class, or rejected. The aims of this paper is to address and discuss two different grading procedures/models that can be applied when settings for IPs that reflects a local board property are derived and to show how the yield in different T-classes depend on the model applied. It is not always that a board’s weakest cross-section is evaluated in a destructive test. An IP representing a local board property can therefore be determined either as the lowest property of the tested part of the board or as the lowest property along the whole board when applied to derive settings. Results presented in this paper show that too low settings and too large yields are obtained when the latter IP is employed. Similarly, IPs reflecting a global board property, like axial dynamic MOE, also give too low settings and too high yield in strength classes. This paper is the second and closing part of a series of two paper on prediction of GDPs and procedures for grading sawn timber into T-classes.

Evaluation of Lumber from Deconstructed Portland Residential Buildings

Portland, Oregon was the first U.S. city to implement a deconstruction ordinance in 2016. Although salvaged lumber from deconstructed dwellings can have high demand, the market for small-sized lumber is near saturation. New applications for this material are required for market development, industry diversification and the possible expansion of the deconstruction ordinance. Its use in mass timber is an option, but presently no wood property information exists for lumber from deconstructed dwellings inhibiting its use for structural purposes. Density and dynamic MOE (E) of 265, 38 mm x 89 mm (2 x 4) pieces of salvaged Douglas fir (Pseudotsuga menziesii) lumber were determined using a Metriguard Model 340 E-Computer. Additional data collected included sample dimensions, weight, and visual appearance. Over 50% of samples had a calculated stiffness comparable to the highest structural design grade for Coastal Douglas fir lumber. The presence of knots and damage, present in 66% and 59% of boards respectively, would likely downgrade boards, despite acceptable stiffness. Results show that 96% of samples were sufficiently stiff to meet minimum requirements for the manufacture of E3 grade cross laminated timber (CLT) panels and considering defects, this material is suitable for manufacturing CLT. Provision of wood property information for salvaged lumber is critical for market expansion and this work represents the first characterization of lumber from deconstructed Portland, OR dwellings.

Strength prediction of timber boards using 3D FE-analysis

Timber boards are numerically reconstructed in the full 3D space based on knot information on the wood surface. The 3D model is then transformed into a full 3D-FEM model and successively used for tensile strength prediction. By knowing the exact locations of the knots, as the main strength governing parameters in timber boards, simulations are run for a large quality range of wood laminations. This includes low-medium quality Douglas fir and medium-high quality spruce boards. ABAQUS and PYTHON are used for the numerical simulations. An automatic link is programmed to extract data of the database and to create the 3D geometrical model. From the numerical simulations, three mathematical methods are presented to calculate the stress concentration factors (SCFs) around the 3D heterogeneous defects in anisotropic wooden boards. Additionally, the explicit dynamic analysis are run to obtain the dynamic modulus of elasticity (MoEdyn). To reduce the dependency of the numerical predictions on the real density of the boards, the average density of each sample is used for the simulations. Each board is tested in tension physically and is used for the validation of the model. The FEM results are used in a regression analysis to analyze the correlation with the visual measurements and to predict the tensile strength. Based on the results of a multiple regression analysis, two SCFs and MoEdyn are sufficient to accurately predict the strength of spruce and Douglas fir boards. The results of the current study show that an improvement in the strength prediction of wood is possible in comparison with current machine grading systems based on dynamic MoE and knot parameters.

Factors influencing the production of structural plywood in Tasmania, Australia from Eucalyptus nitens rotary peeled veneer

Harvested logs supplied from five fibre-managed Eucalyptus nitens plantation coupes with different growing environments were assessed for quality and stiffness. Billets extracted from the logs were rotary peeled for veneer. When averaged across the five coupes, 30% of veneer recovered could be used directly in structural plywood production and an additional 20–25% could be used after further processing. In visual assessment most veneer was assigned an Australian/New Zealand Standard AS/NZS2269.0:2012 Quality D. Acoustic testing during processing showed veneer peeled from a drier and lower elevation coupe had significantly higher dynamic MOE values than veneer processed from logs harvested from wetter higher elevation coupes. To examine the utility of the E. nitens peeled veneer in the production of structural plywood, it was combined with veneer of a known higher stiffness, rotary peeled from regrowth forest Tasmanian oak species logs. Structural seven-ply panels were manufactured from the veneer prepared in three different ply arrangements. Mechanical testing of the panels in accordance with AS/NZS2269.0:2012 showed that an F17 target stress-grade panel product of 83% E. nitens and 17% Tasmanian oak species could be produced, if E. nitens veneer of higher stiffness were selected from veneer segregated by estimated dynamic Modulus of Elasticity value. Panels with 50% E. nitens and 50% Tasmanian oak veneer could be produced by selecting E. nitens veneer of lower stiffness after segregation. In the majority of panels tested stress-grade rating was limited by perpendicular bending strength. Outcomes from the study indicate that structural plywood can be manufactured using differing proportions of E. nitens veneer, rotary peeled from fibre-managed plantations, provided it can be segregated into stiffness categories and selected to achieve a target stress-grade.

Effect of genetic sources on anatomical, morphological, and mechanical properties of 14-year-old genetically improved loblolly pine families from two sites in the southern United States

Tree improvement programs on loblolly pine (Pinus taeda) in the southeastern USA has focused primarily on improving growth, form, and disease tolerance. However, due to the recent reduction of design values for visually graded southern yellow pine lumber (including loblolly pine), attention has been drawn to the material quality of genetically improved loblolly pine. In this study, we used the time-of-flight (TOF) acoustic tool to assess the effect of genetic families on diameter, slenderness, fiber length, microfibril angle (MFA), velocity and dynamic stiffness estimated using green density (DMOEG) and basic density (DMOEB) of 14-year-old loblolly pine stands selected from two sites. All the 184 and 204 trees of the selected eight half-sib genetic families on sites 1 and 2 respectively were tested using TOF acoustic tool, and two 5 mm core samples taken at breast height level (1.3 m) used to for the anatomical and physical properties analysis. The results indicated a significant positive linear relationship between dynamic MOEs (DMOEG and DMOEB) versus tree diameter, slenderness, and fiber length while dynamic MOEs negatively but nonsignificant correlated with MFA. While there was no significant difference in DMOEB between sites; velocity2 for site 1 was significantly higher than site 2 but DMOEG was higher for site 2 than site 1. Again, the mean DMOEG and DMOEB reported in the present study presents a snapshot of the expected static MOE for green and 12% moisture conditions respectively for loblolly pine. Furthermore, there were significant differences between families for most of the traits measured and this suggests that forest managers have the opportunity to select families that exhibit the desired fiber morphology for final product performance. Lastly, since the dynamic MOE based on green density (DMOEG), basic density (DMOEB) and velocity2 present difference conclusions, practitioners of this type of acoustic technique should take care when extrapolating results across the sites.

Wood quality assessment of Pinus radiata (radiata pine) saplings by dynamic mechanical analysis

The use of dynamic mechanical analysis was explored as a possible method of screening for wood quality in breeding programmes. Viscoelastic properties along the grain of wood from 18-month-old Pinus radiata saplings were measured using a humidity-controlled dynamic mechanical analyser. Storage modulus and tanδ were determined independently for opposite wood (OW) and compression wood (CW) in 25 trees in the temperature range from 10 to 45 °C at 5 °C intervals at three frequencies (0.1, 1 and 10 Hz) at constant moisture content of 9 %. Storage modulus and tanδ were frequency and temperature dependent. The two wood types did not differ significantly in their storage modulus. But OW exhibited significantly higher tanδ values than CW. The relationship of viscoelastic properties with physical (acoustic velocity, basic density and longitudinal shrinkage) and chemical wood properties was explored. There was a strong correlation (R = 0.76) between storage modulus and dynamic MOE (measured by acoustics). In addition, tanδ was positively correlated with longitudinal shrinkage. Monosaccharide compositions of the cell wall polysaccharides and lignin contents were determined and showed significant differences in the relative proportion of major cell wall components in OW and CW. Correlations between tanδ and xylose, originating from heteroxylans, and lignin content were found for CW, suggesting that the damping behaviour of cell walls is controlled by the matrix between cellulose fibril aggregates.

Changes in The Dynamic and Static MOE of Furfuryl Alcohol–Treated Wood

Changes in The Dynamic and Static MOE of Furfuryl Alcohol–Treated Wood

Destructive and non-destructive evaluation of seven hardwoods and analysis of data correlation

Abstract Wood physical and mechanical properties in seven tropical hardwood species viz., Acacia auriculiformis A. Cunn. ex Benth., Artocarpus hirsutus Lamk., Artocarpus heterophyllus Lamk., Swietenia macrophylla King, Xylia dolabriformis Benth., Hevea braziliensis (H.B.K.) M. A.), and Tectona grandis L.f. have been studied by means of destructive and non-destructive techniques (NDT). Mechanical strength properties and specific gravity were evaluated by conventional methods. NDT was carried out by a Pilodyn and Treesonic Microsecond Timer (TMT) to measure a steel pin penetration depth into wood and dynamic MOE, respectively. In focus was the question, whether NDT data are suitable predictors for physical and mechanical properties of the indicated hardwood species. Dynamic MOE obtained by TMT correlated strongly positive with all the strength properties studied, except shearing stress. TMT data also correlated very well to static bending MOE and MOR. A linear relationship was found between Pilodyn steel pin penetration depth and oven dry specific gravity in all the species. Both Pilodyn and TMT proved to be useful predictors of timber properties, and these instruments have a high potential for timber grading.

Predicting the young’s modulus of defect free radiata pine shooks in finger-jointing using resonance frequency

In this paper, dynamic MOE and static MOE of short-length radiata pine specimens produced for finger jointing were measured using non-destructive technique and correlated to each other. In order to obtain reliable static MOE data, 36 mm thickness shooks as well as the matched samples of reduced thickness (15mm) were tested, and the effect of annual growth rings on dynamic and static MOE is also addressed. Mathematical correlations were fitted between the dynamic MOE for the 36 mm thick shooks and the static MOE of the 15 mm thick samples. The coefficient of determination for dynamic MOE group 4,00-7,99 GPa was the strongest (R 2 = 0,82) and the correlation strength was further improved for sorted quarter sawn samples (R 2 = 0,92). Finally, the correlation between static modulus of rupture (MOR) and dynamic MOE is discussed.

Application of Nondestructive Methods to Evaluate Mechanical Properties of 32-Year-Old Taiwan Incense Cedar (Calocedrus formosana) Wood

The objective of this work was to assess the physical and mechanical properties of standing Taiwan incense cedar (Calocedrus formosana) using nondestructive techniques (NDT). In addition, the relationship between characteristics of standing trees and wood properties was established. Results indicated that the velocity values and bending properties decreased as tree height increased. In addition, velocity values of specimens were greater than those of logs and standing trees. After regressive analysis, the correlation coefficients (r) were 0.79 for standing trees and logs and 0.70 for logs and specimens. Not only the velocities measured by ultrasonic wave (Vu), tap tone (Vf), and vibration (Vt) methods, but dynamic MOE also correlated well with the static bending properties of specimens. In addition, the values of dynamic and static MOE showed the following trend: DMOEu > DMOEf > DMOEt > MOE. For all specimens, the r values were found to be 0.92 for MOE and DMOEt, and 0.75 for MOR and DMOEt. Therefore, it was assumed that the nondestructive testing methods can provide basic information about standing trees and specimens for future management practices and utilization of Taiwan incense cedar.

Effects of ACQ preservative treatment on the mechanical properties of hardwood glulam

The purpose of this study is to examine the mechanical properties of ACQ-treated glulam made from three hardwood lumbers. Two nondestructive methods, ultrasonic wave and tap tone method, were also used in this study. The results showed that the dynamic MOE and static MOE of lumbers decreased with increased ACQ preservative retention. ANOVA showed no significant difference in the MOE values of glulam between untreated and ACQ-treated group. However, it was also found that glulam made from red oak lumbers had the highest bending strength retention ratio. The shear strength of the glulam also showed similar results. Finally, no delaminating was found in all glulams after the specimens under soaked and boiled delamination tests.

Non-Destructive Testing and Performance Analysis of Glass Fiber Reinforced Soybean Straw Particleboard

Using the flexural vibration method of Fast Fourier Transform (FFT) non-destructive testing, the dynamic MOE of glass fiber reinforced soybean straw particleboard has been determined. The regression analysis among the dynamic MOE, the static MOE and MOR has been done, the significant correlation exists among the three values. And the prediction model has been built, the dynamic MOE can be used to realize the quality assessment by using the model. Using glass fiber to reinforce the soybean straw particleboard, the structure forms and positions of glass fiber have different effects on particleboard performance.

Effects of moisture content and temperature on acoustic velocity and dynamic MOE of radiata pine sapwood boards

The effects of moisture content from 17 to 159% MC and temperatures from −71°C to +58°C on resonance-based acoustic velocity and dynamic modulus of elasticity (DMOE) were investigated using 36 boards of radiata pine sapwood. Acoustic velocity decreased with increasing moisture content and temperature, although effects differed noticeably below and above fibre saturation point (FSP). Below FSP, acoustic velocity decreased rapidly and linearly with increasing moisture; whereas above FSP changes in velocity were rather gradual and curvilinear with marked differences in velocity patterns between temperatures below and above freezing. Acoustic velocity decreased linearly with increasing temperature but there was an abrupt discontinuity at the freezing point for wood above FSP. Changes in moisture content and temperature affecting wood density and acoustic velocity led to changes in DMOE, although this relationship was not straightforward because changes of velocity with moisture were linear or curvilinear and depended on whether wood was frozen or unfrozen, whereas changes of density with moisture content were invariably linear. For practical work, it is important to estimate the relative effect of changing moisture content or temperature with respect to standard conditions on DMOE, thus general guidelines were devised to account for significant changes.

Influence of moisture content of wood on sound velocity and dynamic MOE of natural frequency- and ultrasonic runtime measurement

This study comprises the analysis of the influence of the moisture content of wood on the dynamic properties—sound velocity and dynamic MOE (considering the density)—of green and dry sawn timber. The main objective was to find applicable functions or factors for the adjustment of the determined properties on the reference condition (moisture content u=12%) for the moisture content range below and above fiber saturation. Therefore, two dynamic measurement methods—measurement of the natural frequency and ultrasonic runtime—were considered. Possible differences in the results, pros and cons of both methods should be identified on the one hand. On the other hand, the applicability of already published moisture adjustments to the given data of both methods should be proved.

PENDUGAAN KEKAKUAN KAYU BORNEO DENGAN METODE GELOMBANG ULTRASONIK

Borneo wood is a name for various species commercial wood. The aimed of this study are measured stifness (MOE) of borneo wood using non destructive method i.e. ultrasonic wave. Fiveteen beam sample were produced from borneo wood about 8 cm thick and 12 cm width with 400 cm, 250 cm and 150 cm length. Beam with 250 cm and 150 cm length produced from beam with 400 cm length after stifness test have done using ultrasonic (dynamic test) and UTM (static test). Result showed that dynamic MOE of borneo wood for 400 cm, 250 cm and 150 cm length, are 19.10 G.Pa, 18.48 G.Pa and 15.90 G.Pa, respectively. Wood about 400 cm and 150 cm length were different significantly. Result also showed that dynamic MOE of borneo wood 30% higher than static MOE at vertical position test for beam with 400 cm length and 20% higher for horisontal position at the same testing method. Key words : Borneo wood, stifness, ultrasonic, MOE, MOR