[1b] Arboriculture & Urban Forestry 42(4): July 2016 𝜌𝜌弶ﭒ = density �980 cm/𝑚𝑚弶ﭒ 2∗volume 𝑐𝑐弶ﭒ 𝑚𝑚弶ﭒ 3 𝑚𝑚弶ﭒ 𝑚𝑚弶ﭒ 𝑚𝑚弶ﭒ 𝑚𝑚弶ﭒ (𝑔𝑔弶ﭒ ) [2] ences in moisture content compared to 50°C. Mois- ture content (MC) was calculated as Equation 3: [2a] [3] [3] � 𝑁𝑁弶ﭒ 𝑚𝑚弶ﭒ 2� 𝑥𝑥弶ﭒ 109 𝐷𝐷弶ﭒ 𝑀𝑀弶ﭒ = 𝑤𝑤弶ﭒ 𝑠𝑠弶ﭒ 𝑙𝑙弶ﭒ 𝑤𝑤弶ﭒ 𝑠𝑠弶ﭒ 𝑟𝑟弶ﭒ 𝑔𝑔弶ﭒ ℎ𝑙𝑙弶ﭒ −𝑟𝑟弶ﭒ 𝑟𝑟弶ﭒ 𝑑𝑑弶ﭒ 𝑤𝑤弶ﭒ 𝑠𝑠弶ﭒ 𝑟𝑟弶ﭒ 𝑔𝑔弶ﭒ ℎ𝑙𝑙弶ﭒ 𝑟𝑟弶ﭒ 𝑟𝑟弶ﭒ 𝑑𝑑弶ﭒ 𝑤𝑤弶ﭒ 𝑠𝑠弶ﭒ 𝑟𝑟弶ﭒ 𝑔𝑔弶ﭒ ℎ𝑙𝑙弶ﭒ ∗ 100 Statistical analysis used t-tests, paired t-tests, and regression analysis conducted in SAS 9.4 using α = 0.05. Statistical parameter data and residu- als were tested and determined to be normal. 𝐷𝐷弶ﭒ 𝑆𝑆弶ﭒ = (4×∗𝑚𝑚弶ﭒ 𝑠𝑠弶ﭒ 𝑠𝑠弶ﭒ 𝑠𝑠弶ﭒ 𝑠𝑠弶ﭒ ∗×(𝑠𝑠弶ﭒ 𝑠𝑠弶ﭒ 𝑛𝑛弶ﭒ 𝑔𝑔弶ﭒ 𝑙𝑙弶ﭒ ℎ3)) 48∗×𝜋𝜋弶ﭒ ∗×(𝑟𝑟弶ﭒ 𝑚𝑚弶ﭒ 𝑟𝑟弶ﭒ 𝑟𝑟弶ﭒ 𝑟𝑟弶ﭒ 𝑚𝑚弶ﭒ 4) � , (Equation 2, ASTM 2005) 229 Figure 1. Measuring dynamic modulus of elasticity (DMOE) with the Fakopp stress-wave microsecond timer. Flexural Modulus of Elasticity Directly aſter DMOE testing, the samples were sub- jected to a three-point bending test, with a span of 44.45 cm using a UTM (model MTS 810, Instron®, Norwood, Massachusetts, U.S.) (Figure 2) at a rate of 0.16 cm per minute. The span/depth ratio was select- ed in accordance to a 14:1 cm length to diameter ratio as recommended by the ASTM D 198-05 (ASTM 2005) to minimize shear. The slope of the force versus deformation regression was determined for each sample from the load press output, and flexural modulus of elasticity was calculated as Equation 2: [1] [1a] [1b] � 𝑛𝑛弶ﭒ 𝜌𝜌弶ﭒ = density �980 cm/𝑚𝑚弶ﭒ 2∗volume 𝑐𝑐弶ﭒ 𝑚𝑚弶ﭒ 3 [1b] [1a] 𝑚𝑚弶ﭒ 𝑚𝑚弶ﭒ 𝑚𝑚弶ﭒ 𝑚𝑚弶ﭒ (𝑔𝑔弶ﭒ ) 𝑚𝑚弶ﭒ 2� 𝑥𝑥弶ﭒ 109 [2] where ES [2] [2a] [3] 𝐷𝐷弶ﭒ 𝑆𝑆弶ﭒ = (4×∗𝑚𝑚弶ﭒ 𝑠𝑠弶ﭒ 𝑠𝑠弶ﭒ 𝑠𝑠弶ﭒ 𝑠𝑠弶ﭒ ∗×(𝑠𝑠弶ﭒ 𝑠𝑠弶ﭒ 𝑛𝑛弶ﭒ 𝑔𝑔弶ﭒ 𝑙𝑙弶ﭒ ℎ3)) 48∗×𝜋𝜋弶ﭒ ∗×(𝑟𝑟弶ﭒ 𝑚𝑚弶ﭒ 𝑟𝑟弶ﭒ 𝑟𝑟弶ﭒ 𝑟𝑟弶ﭒ 𝑚𝑚弶ﭒ 4) � 𝑁𝑁弶ﭒ = flexural modulus of elasticity in gigapascals � 𝑁𝑁弶ﭒ 𝑚𝑚弶ﭒ 2� 𝑥𝑥弶ﭒ 109 [2] [2a] [3] 𝐷𝐷弶ﭒ 𝑆𝑆弶ﭒ = (4×∗𝑚𝑚弶ﭒ 𝑠𝑠弶ﭒ 𝑠𝑠弶ﭒ 𝑠𝑠弶ﭒ 𝑠𝑠弶ﭒ ∗×(𝑠𝑠弶ﭒ 𝑠𝑠弶ﭒ 𝑛𝑛弶ﭒ 𝑔𝑔弶ﭒ 𝑙𝑙弶ﭒ ℎ3)) 48∗×𝜋𝜋弶ﭒ ∗×(𝑟𝑟弶ﭒ 𝑚𝑚弶ﭒ 𝑟𝑟弶ﭒ 𝑟𝑟弶ﭒ 𝑟𝑟弶ﭒ 𝑚𝑚弶ﭒ 4) 𝑚𝑚弶ﭒ 2� 𝑥𝑥弶ﭒ 109 Length = the overall test span of the sample (m) Radius = the average radius of the overall sample taken at three points: large-end radius, middle radius, and small-end radius (m) Slope = slope of the linear region taken from the force (n) versus deflection (m) curve 𝐷𝐷弶ﭒ 𝑀𝑀弶ﭒ = 𝑤𝑤弶ﭒ 𝑠𝑠弶ﭒ 𝑙𝑙弶ﭒ 𝑤𝑤弶ﭒ 𝑠𝑠弶ﭒ 𝑟𝑟弶ﭒ 𝑔𝑔弶ﭒ ℎ𝑙𝑙弶ﭒ −𝑟𝑟弶ﭒ 𝑟𝑟弶ﭒ 𝑑𝑑弶ﭒ 𝑤𝑤弶ﭒ 𝑠𝑠弶ﭒ 𝑟𝑟弶ﭒ 𝑔𝑔弶ﭒ ℎ𝑙𝑙弶ﭒ 𝑟𝑟弶ﭒ 𝑟𝑟弶ﭒ 𝑑𝑑弶ﭒ 𝑤𝑤弶ﭒ 𝑠𝑠弶ﭒ 𝑟𝑟弶ﭒ 𝑔𝑔弶ﭒ ℎ𝑙𝑙弶ﭒ ∗ 100 𝐷𝐷弶ﭒ 𝑀𝑀弶ﭒ = 𝑤𝑤弶ﭒ 𝑠𝑠弶ﭒ 𝑙𝑙弶ﭒ 𝑤𝑤弶ﭒ 𝑠𝑠弶ﭒ 𝑟𝑟弶ﭒ 𝑔𝑔弶ﭒ ℎ𝑙𝑙弶ﭒ −𝑟𝑟弶ﭒ 𝑟𝑟弶ﭒ 𝑑𝑑弶ﭒ 𝑤𝑤弶ﭒ 𝑠𝑠弶ﭒ 𝑟𝑟弶ﭒ 𝑔𝑔弶ﭒ ℎ𝑙𝑙弶ﭒ 𝑟𝑟弶ﭒ 𝑟𝑟弶ﭒ 𝑑𝑑弶ﭒ 𝑤𝑤弶ﭒ 𝑠𝑠弶ﭒ 𝑟𝑟弶ﭒ 𝑔𝑔弶ﭒ ℎ𝑙𝑙弶ﭒ ∗ 100 � 𝜌𝜌弶ﭒ = density �980 cm/𝑚𝑚弶ﭒ 2∗volume 𝑐𝑐弶ﭒ 𝑚𝑚弶ﭒ 3 (ASTM 2005) 𝑚𝑚弶ﭒ 𝑚𝑚弶ﭒ 𝑚𝑚弶ﭒ 𝑚𝑚弶ﭒ (𝑔𝑔弶ﭒ ) , (Equation 2, ASTM 2005) 𝐷𝐷弶ﭒ 𝐷𝐷弶ﭒ 𝐷𝐷弶ﭒ 𝐷𝐷弶ﭒ = 𝑐𝑐弶ﭒ 2 × 𝜌𝜌弶ﭒ , (Equation 1, DeVallance et al. 2011) 𝑚𝑚弶ﭒ 2� 𝑥𝑥弶ﭒ 109 [1] � , (Equation 2, ASTM 2005) 𝐷𝐷弶ﭒ 𝐷𝐷弶ﭒ 𝐷𝐷弶ﭒ 𝐷𝐷弶ﭒ = 𝑐𝑐弶ﭒ 2 × 𝜌𝜌弶ﭒ , (Equation 1, DeVallance et al. 2011) � 𝑛𝑛弶ﭒ Figure 2. Measuring flexural modulus of elasticity (ES the universal load press. RESULTS & DISCUSSION Aſter testing modulus of elasticity, a disc (approxi- mately 2 cm) was cut from each stump sprout and weighed, then oven dried for three days at 50°C in an Isotemp™ 500 Series oven (Fisher Scientific Co. LLC, Pittsburgh, Pennsylvania, U.S.) to determine the dry weight. The weight of each sample was mea- sured on Day Two and Day Three and no differ- ence were found. A subsequent evaluation of drying samples at 103°C found only minor (<5%) differ- The ability to determine the material proper- ties of green wood in a standing tree can aid the arboricultural practitioner and researcher in pre- dicting the stability of a tree or branch. Knowing E is important and useful during tree pull tests to assess stability (Wessolly and Erb 1998; Bruechert et al. 2000; Brudi and Van Wassen- aer 2001). A long branch, such as a fast-growing water sprout with a disproportional amount of flexible juvenile wood, may bend too much un- der loading, leading to failure. In addition to ontogenetic shifts in E, there may be shifts due to reaction wood (Kane and Ryan 2003), which may influence the categorization of the likeli- hood of failure during tree risk assessments. A UTM is a direct measure of materials elas- ticity (ASTM 2005), yet this requires destructive testing and takes a significant amount of time. The ability to use a portable acoustical stress-wave system can allow a rapid estimation of flexure modulus of elasticity without the need for destruc- ©2016 International Society of Arboriculture ) with
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