scholarly journals Non-Destructive Measurement of the Modulus of Elasticity of Wood Using Acoustical Stress Waves

2016 ◽  
Vol 42 (4) ◽  
Author(s):  
Gregory Dahle ◽  
Aaron Carpenter ◽  
David DeVallance
Keyword(s):  
Stress Wave ◽  
Modulus Of Elasticity ◽  
Flexural Modulus ◽  
Testing Machine ◽  
Prediction Equation ◽  
Biomechanical Models ◽  
Standing Trees ◽  
Acoustic Testing ◽  
Destructive Measurement ◽  
Non Destructive

Many biomechanical models include modulus of elasticity (E) but it is not always available in the literature. It would be useful to directly measure E for species, and one of the standard techniques for doing so is to utilize a universal testing machine (UTM). While laboratory testing can determine static flexural modulus of elasticity using a UTM, it requires destructive sampling and therefore is only useful after a tree or limb has been removed. Acoustic testing can be used to estimate the dynamic modulus of elasticity (DMOE) of wood, by measuring the speed of sound through a sample of wood without the need to remove any wood samples. This research investigated if acoustic testing can be used to accurately estimate the modulus of elasticity of green wood. Stump sprouts arising after a shelterwood harvest were cut and left at room temperature (21.1°C, warm) or conditioned to -6.7°C (frozen). The modulus of elasticity was measured using a stress-wave timer (DMOE) and a UTM (ES). The DMOE was higher in the frozen samples, but temperature did not affect ES. While the stress-wave timer used in the study found a slightly higher E than a UTM, a simple prediction equation was determined for converting the results. Researchers believe tools such as this can be successfully utilized by the arboriculture industry to rapidly assess the modulus of elasticity of standing trees in the field.

Study on the Correlation between Mechanical Characteristics and Non-Destructive Testing of Stress Wave in Larch Logs

2012 ◽  
Vol 433-440 ◽  
pp. 2135-2141
Author(s):  
Ju Ying Luo ◽  
Xue Chun Yang
Keyword(s):  
Stress Wave ◽  
Linear Correlation ◽  
Modulus Of Elasticity ◽  
Dynamic Modulus ◽  
Testing Machine ◽  
Non Destructive Testing ◽  
Destructive Testing ◽  
Dynamic Modulus Of Elasticity ◽  
Positive Linear Correlation ◽  
Non Destructive

The testing experiments to healthy larch logs samplings whose diameter scopes are in 5-12cm and the length respectively are 10cm and 30cm were conducted by using Arbotom stress wave testing instrument and universal mechanics testing machine. The relationships between dynamic modulus of elasticity of stress wave and MOE, between MOR and MOE were all studied in the larch logs samplings. The results indicated that, in the two larch logs samplings, the dynamic modulus of elasticity of stress wave had positive linear correlation with MOE. Moreover, MOR also had a good linear correlation with MOE.

Non-Destructive and Semi-Destructive Test Methods for Strength Determination of Aged Wood

2013 ◽  
Vol 778 ◽  
pp. 385-392
Author(s):  
Anton Kraler ◽  
Wilfried Beikircher
Keyword(s):  
Testing Machine ◽  
Constant Load ◽  
Test Methods ◽  
Climatic Conditions ◽  
Measurement Methods ◽  
Compression Tests ◽  
Starting Point ◽  
Destructive Measurement ◽  
Non Destructive

To what extent is there a change in the strength of wood over the course of centuries, when installed under a constant load? Are there non-destructive measurement methods for the determination of strength that are suitable for this investigation? These two questions were the starting point of this research project. Through experience we have learned that the strength of wood is dependent on the growth regions and climatic conditions in which it originates. For example, over centuries, in a northern Italian valley, there were commonly known and clearly defined areas which provided the wood for the construction of the local buildings. Another decisive factor for selecting this research region was that the buildings concerned had already been dated by means of dendrochronology. This created a unique situation in that the strength of the timber in these buildings, which cover about nine centuries (1250 to present), could be compared and analyzed. Local spruce and larch used in the construction typical of this region were selected for the investigations. Starting with 1250AD (the oldest dated wood construction) and in consecutive steps of 100 years, two projects (of the entire 18 projects) are selected and explored. Three non-destructive and respectively semi-destructive measurement methods were used for the strength testing. The measurement devices are: for drill resistance measuring IML-RESI F400S, for the fractometer tests (bending and compression tests) IML-Instrumenta Mechanik Labor Gmbh. For ultrasonic testing the device Sylvatest duo is used. So the validity of the measurement systems used could be brought into relation with the actual strength. Some small, flawless samples (without knots) from selected projects were removed and then tested in a laboratory with the universal testing machine Shimadzu 100KN.

scholarly journals Prediction of the modulus of elasticity of Eucalyptus grandis through two nondestructive techniques

2014 ◽  
Vol 21 (3) ◽  
pp. 369-375 ◽  
Author(s):  
Pedro Henrique Gonzalez de Cademartori ◽  
André Luiz Missio ◽  
Darci Alberto Gatto ◽  
Rafael Beltrame
Keyword(s):  
Stress Wave ◽  
Modulus Of Elasticity ◽  
Eucalyptus Grandis ◽  
Ultrasonic Technique ◽  
Bending Tests ◽  
Nondestructive Tests ◽  
Universal Machine ◽  
Nondestructive Techniques ◽  
Ultrasonic Techniques ◽  
Non Destructive

The present study aimed to estimate the modulus of elasticity (MOE) at static bending of Rose gum (Eucalyptus grandis) heartwood and sapwood through two nondestructive techniques: ultrasound and stress wave. Sixty samples of heartwood and sapwood were prepared. Nondestructive tests were performed using ultrasound and stress wave timer equipment, while destructive tests were carried out in a universal machine through static bending tests. The main results showed that the heartwood presented better behavior than the sapwood in the non-destructive tests. However, the best model was obtained considering both wood types through the ultrasonic technique. Therefore, stress wave and ultrasonic techniques could be employed to estimate the modulus of elasticity of Rose gum wood.

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