Effect of Green Tea Content on Dynamic Modulus of Elasticity of Hybrid Boards Composed of Green Tea and Wood Fibers, and Prediction of Static Bending Strength Performances by Flexural Vibration Test

Before round timber can be profitably used in construction, it needs structural characterization. The visual grading of Eucalyptus grandis poles was integrated with additional parameters developed by multivariate regression analysis. Acoustic velocity and dynamic modulus of elasticity were combined with density and pole diameter in the estimation of bending strength and stiffness. The best models achieved were used to group the visually graded material into qualitative structural classes. Overall, dynamic modulus of elasticity was the best single predictor; and adding density and diameter to the model improved the estimation of strength but not of stiffness. The developed parameters separated the material into two classes with very distinct mechanical properties. The models including velocity as a parameter did not perform as well. The strength grading of Eucalyptus grandis poles can be effectively improved by combining visual parameters and nondestructive measurements. The determination of the dynamic modulus of elasticity as a grading parameter should be preferred over that of acoustic velocity.

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Ultrasonic and Vibration Signals Processing for Computing Dynamic Modulus of Elasticity of Intact and Damaged Wood

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.33.295 ◽

2010 ◽

Vol 33 ◽

pp. 295-298

Author(s):

Song Yuan Ni ◽

Hua Dong Xu ◽

Li Hai Wang

Keyword(s):

Signal Processing ◽

Time Domain ◽

Modulus Of Elasticity ◽

Dynamic Modulus ◽

Vibration Signal ◽

Head Wave ◽

Vibration Test ◽

Response Functions ◽

Vibration Signals ◽

Dynamic Modulus Of Elasticity

To effectively and quickly estimate the dynamic modulus of elasticity (MOE) of wood, ultrasonic and vibration test techniques are employed to measure the intact and damaged wood specimens. The ultrasonic and vibration signals in time domain are obtained respectively. Then, the time of flight is received by picking up the position of ultrasonic head wave and it is used to compute the dynamic MOE of wood. Simultaneously, the frequency response functions of wood are received by analyzing the frequency domain signals transformed from time domain using Fourier formulas, and they are used to pick up the intrinsic frequencies to calculate the dynamic MOE measured by vibration test. Finally, the correlations of dynamic MOE tested by these two methods are discussed. The research results show that it is feasible to estimate the dynamic MOE of wood via ultrasonic and vibration signal processing.

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Accounting for the Frequency-Dependent Dynamic Modulus of Elasticity of Duralumin in Deformation Problems

Прикладная механика и техническая физика ◽

10.15372/pmtf20170317 ◽

2017 ◽

Keyword(s):

Modulus Of Elasticity ◽

Dynamic Modulus ◽

Frequency Dependent ◽

Dynamic Modulus Of Elasticity

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ANALYSIS OF SOUND SPEED IN LONGITUDINAL DIRECTION AT REFERENCE MOISTURE CONTENT (w = 12 %) IN SAWMILL ASSORTMENTS (FAGUS SYLVATICA, L.)

Akustika ◽

10.36336/akustika20203745 ◽

2020 ◽

pp. 45-50

Author(s):

Alena Rohanová

Keyword(s):

Moisture Content ◽

Modulus Of Elasticity ◽

Dynamic Modulus ◽

Sound Speed ◽

Longitudinal Direction ◽

Structural Timber ◽

Sound Speeds ◽

Dynamic Modulus Of Elasticity ◽

Round Timber

This paper explores the analysis of sound speeds in the longitudinal direction and their reduction to the reference moisture content w = 12 %. The sound speed cw was determined with Sylvatest Duo device. Moisture content of beech sawmill assortments (round timber: N = 16, logs: N = 2 × 16, structural boards: N = 54) in the range of 12 – 72 % was measured. For the analysis purposes, the sound speed was converted to reference conditions (c12, uref = 12%). A second-degree polynomial (parabola) with a regression equation of the form: c// = 5649 - 27,371 × w + 0.0735 × w2 was used to convert cw to c12, and correction of measured and calculated values was used as well. The sound speeds c12 in sawmill assortments (c12,round, c12,log, c12,board) were evaluated by linear dependences. Dependence was not confirmed for c12,round and c12,board1 (r = 0.168), in contrast for c12,round and c12,log2 the dependence is statistically very significant (r = 0.634). The results of testing showed that the most suitable procedure for predicting quality of structural timber is the first step round timber – log2, the second step: log2 - board2. More exact results of the construction boards were obtained from log2 than from log1. The sound speed is used in the calculation of dynamic modulus of elasticity (Edyn). EN 408 mentions the possibility of using dynamic modulus of elasticity as an alternative method in predicting the quality of structural timber.

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Diagnosis and Assessment of Deep Pile Cap Foundation of a Tall Building Affected by Internal Expansion Reactions

Buildings ◽

10.3390/buildings11030104 ◽

2021 ◽

Vol 11 (3) ◽

pp. 104

Author(s):

Fernando A. N. Silva ◽

João M. P. Q. Delgado ◽

António C. Azevedo ◽

Tahlaiti Mahfoud ◽

Abdelhafid Khelidj ◽

...

Keyword(s):

Compressive Strength ◽

Reinforced Concrete ◽

Modulus Of Elasticity ◽

Dynamic Modulus ◽

Structural Integrity ◽

Gas Permeability ◽

Ettringite Formation ◽

Dynamic Modulus Of Elasticity ◽

Pile Cap ◽

Deterioration Process

Early deterioration of reinforced concrete foundations has been often reported in recent years. This process is usually characterized by an extensive mapping cracking process on concrete surfaces that results from several types of Internal Swelling Reaction (ISR). In this paper, a real case study of a tall reinforced concrete building with a severe deterioration process installed in its deep foundations is discussed. Laboratory tests were performed in concrete drilled cores extracted from a deep pile cap block 19 years after the beginning of construction. Tests to assess the compressive strength, the static and the dynamic modulus of elasticity, the gas permeability, and electron microscopy scanning to find out the primary mechanism responsible for the deterioration observed during in situ inspections. Chemical alterations of materials were observed in concrete cores, mainly due to Delayed Ettringite Formation (DEF), which significantly affected the integrity and durability of the structure. Dynamic modulus of elasticity showed to be a better indicator of damage induced by ISR in concrete than compressive strength. Procedures to strengthen the deteriorated elements using prestressing proved to be an efficient strategy to recover the structural integrity of pile caps deteriorated due to expansions due to ISR.

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Young’s and shear moduli of glued laminated timber composed of different species obtained by a flexural vibration test

Holzforschung ◽

10.1515/hf-2011-0209 ◽

2012 ◽

Vol 66 (7) ◽

pp. 871-875 ◽

Cited By ~ 3

Author(s):

Yoshitaka Kubojima ◽

Mario Tonosaki

Keyword(s):

Elastic Constants ◽

Pinus Densiflora ◽

Flexural Vibration ◽

Japanese Cedar ◽

Picea Sitchensis ◽

Vibration Test ◽

Shear Moduli ◽

Glued Laminated Timber ◽

Flexural Vibration Test ◽

Lamination Theory

Abstract The applicability of the flexural vibration test to determine the elastic constants of glued laminated timber (GLT) composed of five wood species (ash, Fraxinus spaethiana Lingelsh.; balsa, Ochroma pyramidale Urban.; Japanese cedar, Cryptomeria japonica D. Don; Japanese red pine, Pinus densiflora Sieb. et Zucc.; Sitka spruce, Picea sitchensis Carr.) has been investigated. GLT models were prepared from four laminae with dimensions of 30 (R)×5 (T)×300 (L) mm3. The suitability of Japanese cedar for inner layers in GLTs was tested by flexural vibration test to determine the elastic constants of the laminae and the glued laminated timber. The Young’s and shear moduli were calculated by the Goens-Hearmon regression method based on the Timoshenko theory of bending (TGH method), and the results were compared with the estimated values based on the Young’s and shear moduli measured individually of each lamina. The simple lamination theory was found to be applicable for Young’s modulus but not to shear modulus. The result obtained based on the lamination theory from the shear strain energy was similar to that obtained by the TGH method.

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Effects of ring characteristics on the compressive strength and dynamic modulus of elasticity of seven softwood species

Holzforschung ◽

10.1515/hf.2007.077 ◽

2007 ◽

Vol 61 (4) ◽

pp. 414-418 ◽

Cited By ~ 1

Author(s):

Cheng-Jung Lin ◽

Ming-Jer Tsai ◽

Chia-Ju Lee ◽

Song-Yung Wang ◽

Lang-Dong Lin

Keyword(s):

Compressive Strength ◽

Statistical Analysis ◽

Modulus Of Elasticity ◽

Dynamic Modulus ◽

Ring Width ◽

Ring Density ◽

Dynamic Modulus Of Elasticity ◽

Wave Technique ◽

Wood Strength ◽

Softwood Species

Abstract The effects of ring characteristics on the compressive strength and dynamic modulus of elasticity of seven softwood species in Taiwan were examined. The results revealed good correlation between compressive strength and dynamic modulus of elasticity obtained using an ultrasonic wave technique (correlation coefficient r=0.77–0.86). Overall, compressive strength increased with decreasing ring width parameters and increasing ring density parameters. Ring density was related to compressive strength, but was not the sole factor affecting the wood strength. According to our statistical analysis, compressive strength was affected by various ring characteristics. Relationships between ring characteristics and compressive strength are influenced by the anatomic direction. Results revealed that earlywood density and minimum density in a ring are equally important variables for evaluating the compressive strength of wood.

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Some Dynamic Properties of Rubber

Journal of Applied Mechanics ◽

10.1115/1.4009208 ◽

1942 ◽

Vol 9 (3) ◽

pp. A129-A135

Author(s):

C. O. Harris

Keyword(s):

Modulus Of Elasticity ◽

Dynamic Modulus ◽

Dynamic Properties ◽

Internal Damping ◽

Standard Practice ◽

Dynamic Modulus Of Elasticity

Abstract The purpose of the investigation described in this paper was to obtain information concerning the dynamic properties of rubber bonded to metal. Two properties of rubber were measured (a) the internal damping and (b) the dynamic modulus of elasticity. Two types of specimens were tested (a) rubber cylinders bonded to steel cylinders at the ends and stressed in compression and (b) specimens of rubber bonded to steel and stressed in shear. All specimens were of the same stock, 5140-V-4, manufactured by the U. S. Rubber Company. The hardness, as measured by the durometer, varied from 32 to 40. In the process of bonding to the steel, a 1/32-in. layer of 60-durometer stock was added adjacent to each piece of steel. This represents standard practice of the U. S. Rubber Company in bonding soft stock to metal. All specimens were cured for 30 min at 279 F.

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