Differences In Elastic Modulus Research Articles

Mechanical properties of samama wood (Antocephalus macrophyllus) after boron and castor bean oil impregnation and heat treatment

ABSTRACT This research was conducted to detect changes in the mechanical properties of samama wood (Anthocephalus macrophyllus) after impregnation with boron, castor bean oil, and heat treatment. Samama wood has low durability so samples were impregnated with boric acid followed by impregnation with castor oil in order to achieve some fixation of the boric acid. After impregnation, heat treatments were applied for four hours at 80°C and 160°C. Results showed that the modulus of elasticity (MOE), modulus of rupture (MOR) and hardness of samama wood generally increased after the treatments. Compared with the control, the maximum differences in MOE and MOR were 19.9% and 26.7%, respectively. Castor oil treatment also increased the density and hydrophobicity of the samama wood.

Variation in bending strength properties in stem and branch woods as influenced by density and moisture levels in Entandrophragma cylindricum

ABSTRACTBranchwood is being exploited as a supplement to stemwood in wood products manufacturing, and the wood’s bending strength properties are vital for structural and non-structural applications. Non-destructive methods are being adopted in determining wood properties, and wood density and moisture content are two variables that could be useful. This study assessed the influence of density and moisture content (MC) on the Modulus of Elasticity (MOE) and Modulus of Rupture (MOR) of branch and stem woods of Entandrophragma cylindricum (sapele) tested at two moisture levels (10 ± 4% MC and 17 ± 3% MC). Density was determined in accordance with ISO 3131. To determine bending strength properties, BS 373 was followed, using an INSTRON TCM Machine with a crosshead speed of 6.6 mm per minute. Results indicated that branchwood has higher density than its stemwood counterparts. MOE and MOR of both wood types were significantly higher at 10 ± 4% MC than their counterparts at 17 ± 3% MC. Differences in MOE and MOR between the wood types were not significant, although the branchwood had 87% and 93% respectively of the MOE and MOR of stemwood. From the two-way ANOVA, MC had a significant effect (P < 0.05) but wood type and the interactions of wood type and MC did not have a significant effect on MOE and MOR of stem and branch woods. The predictive powers of MC and density as a combined predictor for estimating bending strength properties were higher for branchwood than stemwood. Although density of E. cylindricum branchwood was significantly higher than its stemwood counterpart that did not translate into significant differences between MOE and MOR of branchwood and stemwood.

Neonatal Pig Femur Integrity Responses to Dietary Vitamin D and P Depend on Maternal Dietary Vitamin D

Kyphosis, an idiopathic disease, occurs in swine and humans. We induced kyphosis by altering maternal dietary vitamin D (D) and pig dietary D, Ca and P. The objective was to characterize bone traits and gene expression in the kyphosis model and assess maternal carryover effects. Traits from mechanical tests to characterize femur integrity are reported herein. Sows were fed diets with 0, 325 or 1750 IU D/kg (n = 6, 8, or 9/diet). At weaning (23 ± 2 d) pigs were fed diets with 0 (-D) or 280 (+D) IU D/kg, each with 95% (95P) or 120% (120P) of the P requirement. Pigs were killed at birth (n = 23), weaning (n = 22), and at the end of nursery (n = 185) for bone and tissue analysis. Excised femurs were subjected to a 4-point bending test to determine bending moment (BM), stress, strain, and modulus of elasticity (ME) at the yield point of load deformation curves. Mass moment of inertia (MOI) was derived from CT scans. ME encompasses of BM, stress, strain and MOI and is assumed to be a constant property of a material. No differences in ME were detected at birth. At weaning ME increased in pigs produced by sows fed 1750 (P < 0.05). At the end of nursery ME depended on maternal diets (interaction, P < 0.05). ME increased in pigs fed +D95P if produced by sows fed 0 or 325 but decreased if produced by sows fed 1750. As previously reported, DXA whole body bone mineral density also indicated maternal carryover effects, but the pattern differed among diets. Therefore whole body bone and femur integrity traits differ, but provide unique characterization of the model. As previously reported, the kyphosis model was further characterized by molecular analysis of bone and D homeostatic cell signaling mechanisms. All traits contribute to the characterization of the kyphosis model but a specific mechanism by which the deformity is induced has yet to be determined.

Modelling between tree and longitudinal variation in green density within Pinus radiata: implications for estimation of MOE by acoustic methods

Instruments based on resonance are widely used in the forest industry to predict modulus of elasticity (MOE) and segregate logs of varying quality for different end uses for fast growing softwoods such as Pinus radiata D. Don. Predictions of MOE, made using resonance instruments, often assume a constant green density, ρg, of 1,000 kg m–3. However, little research has been done to test the robustness of this assumption. The objective of this research was to describe changes in predictive precision of MOE as ρg is increasingly well characterised. Longitudinal measurements of velocity, V, and ρg taken from eighty 17-year old unthinned P. radiata trees growing at two sites in Chile were used to calculate MOE. Predictions of MOE were then made by substituting measurements of ρg for values predicted by the following models (i) Model 1 - assuming a constant ρg of 1,000 kg m−3, (ii) Model 2 - using the mean tree ρg of 914 kg m−3, (iii) Model 3 - using a model with fixed effects to account for the mean longitudinal variation in ρg, (iv) Model 4 - inclusion of previous terms and random effects to account for tree level variation and (v) Model 5 - inclusion of previous effects (in model 4) and a random quadratic term. Differences in MOE determined from measurements of ρg and the five predictions of ρg were expressed as both a percentage difference, (D) and an absolute percentage difference (Da) to assess precision and bias. At the tree level, values for mean D and Da (in brackets) were −9.9 (10.4)%, −0.459 (5.49)%, −0.262 (4.15)%, −0.045 (0.232)% and −0.0406 (0.189)%, for Models 1, 2, 3, 4 and 5, respectively. At the log level, considerable longitudinal bias in D was evident for Model 1 where over-prediction of MOE was greatest between relative heights of >0.1–0.4, with D reaching maximum values of −33.8% between relative heights of >0.1–0.2. Assuming constant ρg can result in substantial error in estimates of MOE using acoustic instruments particularly when predictions are made at the log level. The mixed effects modelling approach described here demonstrates a useful method for characterising variation in ρg allowing more accurate estimates of MOE to be made using acoustic methods.

Magnesium fertilizer, weed control and clonal effects on wood stiffness of juvenile Pinus radiata at two contrasting sites

Two field trials established at contrasting sites (Kaingaroa and Rolleston) with different silvicultural treatments [magnesium (Mg) fertilizer or plus or minus weed control (±WC)] but identical clones of Pinus radiata were measured at age 6 for tree height (Ht), diameter at breast height (DBH) and ground-line (GLD), and modulus of elasticity (MOE) of standing trees. This study was undertaken to (i) quantify the main and interactive effects of clone, site, Mg fertilizer or WC on stem slenderness and corewood MOE of juvenile radiata pine, and (ii) examine the relationships between clonal means of corewood MOE and stem slenderness from 15 selected clones.At the Kaingaroa site, clone had a significant (P<0.001) influence on stem slenderness and corewood MOE, which exhibited a 1.5-fold variation (1.48–2.33GPa). The Mg fertilizer effect on MOE was not significant. At the Rolleston site, both WC and clone had significant (P<0.001) influence on corewood MOE. Compared to −WC, +WC reduced MOE by 7%. The MOE exhibited a 1.7-fold variation (1.67–2.83GPa) among the 15 clones. Across both sites, MOE exhibited a 1.5-fold variation (1.65–2.55GPa) among the 15 clones. Overall, clonal differences in MOE were substantial and larger than the differences due to site and WC. Significant interactions were also found between clone and Mg fertilizer, clone and WC, and clone and site.This study for the first time showed the clonal means of MOE was strongly and positively correlated to clonal means of stem slenderness. This study has the important implication for forest managers that clonal material can be closely matched to site conditions and management regimes to optimise product value.

Strength properties of glued laminated timber made from edge-glued laminae I: strength properties of edge-glued karamatsu (Larix kaempferi) laminae

The object of this study was to investigate the strength properties of edge-glued laminae and to propose a suitable grading method based on the lamina modulus of elasticity (MOE). Edge-glued laminae composed of lumber with similar MOEs (uniform laminae) and edge-glued laminae produced by randomly gluing lumber independent of MOE (random laminae) were made from karamatsu (Larix kaempferi) lumber having the same thickness and length, but various widths. For both the uniform and random laminae, there was a strong correlation between MOE values measured using the longitudinal vibration technique, the static bending test, and a grading machine. The average values of bending, tensile, and compressive strengths of the uniform laminae were similar to those of the random laminae. On the other hand, the average strength of laminae without end joints was significantly higher than that of finger-jointed laminae for both uniform and random laminae. Finger-joints and knots played a significant role in the failure of specimens, but the edge-gluing and the difference in MOE within an edge-glued lamina did not appear to affect the strength properties. The bending, tensile, and compressive strengths of edge-glued laminae were strongly correlated to the lamina MOE.

Characterizing Variability of Commercial Oriented Strandboard: Bending Properties

To characterize the variation in bending modulus of elasticity (MOE) and modulus of rupture (MOR), two commercial oriented strandboard (OSB) products were selected. Master panels from multiopening, large hot presses were cut into standard panels of 1,220 by 2,440 mm, and then a total of 3,420 bending specimens were prepared in a continuous order and tested. The variations in bending properties were compared in terms of coefficient of variation (CV) and property differences both between and within master panels. The differences were evaluated by conducting analysis of variance and least significant difference tests. The correlation between MOE and MOR was also investigated. The results showed that the thicker OSB had less variation in bending properties than the thinner product. The variation of MOE (CV = 12% to 16%) was lower than that of MOR (CV = 20% to 22%). Although no significant differences were found in bending MOE and MOR between master panels, significant variations were noted in MOE and MOR within master panels. The differences in MOE and MOR between standard panels varied from 4 to 11 percent, and those along and across the forming line could vary from 8 to 17 percent and from 33 to 59 percent, respectively. The results suggest that product uniformity needs to be improved both along and across the forming line to lower production cost and improve product performance. The relationship between MOE and MOR was linear, with R2 around 0.7.

Bending Strength and Modulus of Elasticity of Squares with Wane as Compared with Round Timber of Scots Pine (Pinus sylvestris)

A comparison of bending strength and modulus of elasticity (MOE) of squares with wanes to round timber was performed as part of a project on the use of round Scots pine (Pinus sylvestris L.) timber in structural frameworks. The study was based on 125 squares and 124 round logs from two sites at high altitudes and two sites at low altitudes in southern Norway. The effects of wanes were estimated by means of reduction in second moment of area and section modulus. Wanes had significant effect on both bending strength and MOE, but in both cases the effects were minor when compared with the effects of material properties. The reduction of bending stiffness due to wanes was almost as much as expected from lack of section, while the reduction of moment capacity was smaller. Squares with ⅓ wane had both lower bending strength and lower MOE than round timber. According to how bending strength and MOE are calculated, differences due to wane were expected. The observed difference in bending strength was larger than expected through the lack of section, indicating that it was affected by material properties as well. The difference in MOE between round timber and squares with ⅓ wane could be explained by the lack of section according to how these values are calculated. Origin had a significant effect on both bending strength and MOE.

Comparative study on three dynamic modulus of elasticity and static modulus of elasticity for Lodgepole pine lumber

The dynamic and static modulus of elasticity (MOE) between bluestained and non-bluestained lumber of Lodgepole pine were tested and analyzed by using three methods of Non-destructive testing (NDT), Portable Ultrasonic Non-destructive Digital Indicating Testing (Pundit), Metriguard and Fast Fourier Transform (FFT) and the normal bending method. Results showed that the dynamic and static MOE of bluestained wood were higher than those of non-bluestained wood. The significant differences in dynamic MOE and static MOE were found between bulestained and non-bluestained wood, of which, the difference in each of three dynamic MOE (Ep, the ultrasonic wave modulus of elasticity, Em, the stress wave modulus of elasticity and Ef, the longitudinal wave modulus of elasticity) between bulestained and non-bluestained wood arrived at the 0.01 significance level, whereas that in the static MOE at the 0.05 significance level. The differences in MOE between bulestained and non-bluestained wood were induced by the variation between sapwood and heartwood and the different densities of bulestained and non-bluestained wood. The correlation between dynamic MOE and static MOE was statistically significant at the 0.01 significance level. Although the dynamic MOE values of Ep, Em, Ef were significantly different, there exists a close relationship between them (arriving at the 0.01 correlation level). Comparative analysis among the three techniques indicated that the accurateness of FFT was higher than that of Pundit and Metriguard. Effect of tree knots on MOE was also investigated. Result showed that the dynamic and static MOE gradually decreased with the increase of knot number, indicating that knot number had significant effect on MOE value.

Impact of log position in the tree on mechanical and physical properties of black spruce medium-density fibreboard panels

Mechanical and physical properties of medium-density fibreboard (MDF) panels made from black spruce ( Picea mariana (Mill.) BSP) top, middle, and butt logs were studied. The analysis of variance and analysis of covariance were both performed to examine the impact of log position in the tree on panel modulus of rupture (MOR), modulus of elasticity (MOE), internal bond (IB), linear expansion (LE), thickness swell (TS), and water absorption. Results indicate that MOE and IB strength of MDF panels made from top and middle logs were significantly superior to those of panels made from butt logs; however, there was no significant difference in MOE and IB between panels made from top and middle logs. Water absorptions of top and middle log panels were significantly lower than that of panels made from butt logs, and the difference in water absorption between panels made from top and middle logs was not significant. TS of top log panels was the smallest among the panels from the three log positions in the tree and was significantly different from those of middle and butt log panels. TS of butt log panels was the highest, which was significantly different from that of top and middle log panels. The differences in LE among the panels made from top, middle, and butt logs were not significant. The comparison of MOR of top, middle, and butt log panels was dependent on panel density because of the interactions among the three groups. Top and middle log panels showed superior properties, because the thinner cell walls of fibres from top and middle logs resulted in an increased compaction ratio compared with the butt log panels. Panel density affected both panel MOR and MOE considerably; however, its impact on IB, LE, TS, and water absorption was not significant in this study. The equations describing the linear relationships between MOR, MOE, and panel density were developed.

The effect of initial tree-planting density on timber and wood-fuel properties of red alder and sycamore

Studies on red alder (Alnus rubra Bong.) and sycamore (Acer pseudoplatanus L.) were carried out to assess their timber and wood-fuel properties when grown at wide spacing as in a silvopastoral system. Initial tree-planting density had significant effects on the modulus of elasticity (MOE) in red alder and compression strength in sycamore. Wood samples taken from red alder in high-density plots of 2500 stems·ha–1 had a significantly higher MOE than those from trees in low-density plots of 400 stems·ha–1 (silvopastoral system). Sycamore wood from the high-density plots had significantly higher compression strength than that from the low-density plots. However, there was no significant effect of planting density on the modulus of rupture in either species. On average, red alder had lower wood density, modulus of rupture, and compression strength than sycamore, but there was no significant difference in MOE between the two species. Planting density did not have any effect on the wood-fuel higher heating value of either red alder or sycamore, nor was there a significant difference in wood-fuel higher heating value between the two species. However, red alder wood had a significantly higher fuel-value index than sycamore, owing to its lower ash content.

Mechanical analyses of the emplacement of laccoliths and lopoliths

Elastic deformations of host rocks during the emplacement within the Earth's crust of magmatic intrusions, such as laccoliths and lopoliths, are analyzed. The present analysis is built upon semianalytic elastic solutions for a pressurized horizontal crack buried between an overburden and a semi‐infinite base. The current work improves upon recent analyses by including several important features inherent to the development of laccoliths and lopoliths. First, both elongated intrusions (plane strain case) and circular intrusions (axisymmetric case) are described by the current models. Second, the effect of the difference in elastic moduli between the overburden and the substrate is considered. This difference in elastic moduli is characterized by one of the Dundurs parameters. Third, the stress intensity factor at the tip of the crack is assumed to be zero. Thus the stresses are finite, and the obtained laccolithic shapes are doubly hinged with horizontal slopes at the peripheries, as observed in the field. Fourth, unlike plate bending models, which are commonly used for major laccoliths, the current models describe a full range of ratios of intrusion width to overburden thickness. Numerical results are obtained for different combinations of the geometrical parameters, the material contrast and the driving pressure distributions. Graphs of these results confirm the plate bending model for large laccoliths, support Gilbert's concept pertaining to small laccoliths, permit the prediction of the sill‐laccolith transition, allow the analysis of the asymmetry in the vertical displacements above and below the intrusion, and lead to a possible mechanism of deep lopoliths emplacements. Some of the obtained results are compared to the available field data from the Henry Mountains.

Determination of bending modulus of elasticity of Pterygota macrocarpa K. Schum (Kyere) and Piptadeniastrum africanum (Dahoma) using two International testing norms

Two different international testing norms, DIN52186 (1978) and ISO8375 (1985) were used to determine the bending modulus of elasticity (MOE) of Pterygota macrocarpa K. Schum (Kyere) and Piptadeniastrum africanum (Dahoma). The results from the two testing norms for each timber species were highly correlated, with correlation co-efficients of 0.92 and 0.96 obtained for Kyere and Dahoma respectively. The MOE determined using ISO 8375 (1985), employing deflections within loading points (i.e. within the shear free zone) was, however, significantly higher than that determined using DIN 52186 (1978), employing deflections along the whole specimen length, for both species at 5% probability level. The difference in MOE's may be attributed to the influence of shear stresses in bending, in the case of specimens tested using DIN 52186 (1978). The results indicate that, test standards which recommend computation of MOE using total deflection along the whole length of the test specimen may under-estimate the actual rigidity of a wooden member. JOURNAL OF THE GHANA SCIENCE ASSOCIATION Volume 1 Number 3, July (1999) pp. 126-132

Elastic energy of a screw dislocation near a planar interface: effect of inner cut-off

The energy of a screw dislocation near the planar interface separating two isotropic media of different shear moduli is calculated via the work done by surface forces during a virtual process of dislocation creation. In addition to the only term usually considered arising from the cut across the material, contributions from the inner and outer cut-off surfaces have been taken into account. The force on the dislocation arising from the difference in elastic moduli is found neither to diverge nor to vanish at the interface. The critical stress to force the dislocation into a medium with higher modulus is discussed and compared with other calculations based on non local elasticity or a Peierls model. This calculation method of the total elastic strain energy finds a useful application in atomistic calculations of dislocations making possible accurate energy comparisons.

Effects of Difference in Elastic Moduli between Constituents on Spinodal Decomposition Processes

Computer simulations on the spinodal decomposition processes in a bcc binary alloy with a crystal anisotropy were carried out by using a Monte Carlo method combined with a static variational method. The Johnson-type potentials were used for the interaction between the constituent elements in the alloy. We assumed that the elastic modulus of the precipitate was equal to or softer than that of the matrix. In the former case, the wave number (km) corresponding to the maximum in the structure functions along 〈100〉 direction was constant during the initial stage of decomposition, while in the latter case, km decreased with time and the structure functions showed a scaling behavior. Furthermore, only in the latter case, a giant cluster of solute atoms was formed and created a percolative structure at the later stages of aging of the alloy.