Potential Brazilian wood species for bows of string instruments

Holzforschung ◽  
2010 ◽  
Vol 64 (4) ◽  
Author(s):  
Eduardo Luiz Longui ◽  
Daniel Romeu Lombardi ◽  
Edenise Segala Alves
Keyword(s):  
Specific Gravity ◽  
Wood Species ◽  
Modulus Of Elasticity ◽  
Dynamic Modulus ◽  
Sound Propagation ◽  
Raw Material ◽  
Professional Musicians ◽  
String Instruments ◽  
Dynamic Modulus Of Elasticity ◽  
Caesalpinia Echinata

Abstract Caesalpinia echinata Lam. (pau-brasil) is a Brazilian tree with symbolic character for Brazilian forestry, which is at risk of extinction because of illegal logging activities and exportation as raw material for bows of string instruments. Additional studies are required to select substitutes for pau-brasil, i.e., other wood species are being sought with potentially suitable characteristics for bow manufacture. The present paper is dedicated to the evaluation of six native Brazilian woods by comparing their anatomical features, specific gravity, speed of sound propagation, and dynamic modulus of elasticity in relation to the corresponding properties of C. echinata that are considered as standard for bow manufacture. The results showed that length, diameter, lumen diameter, and wall thickness of fibers are the most important variables contributing to specific gravity. Additionally, ray dimensions influenced sonic velocity. The values of dynamic modulus of elasticity are directly related to dimensions of rays and fibers. Among the six woods included in this study, Dipteryx spp., Handroanthus spp., and Hymenaea spp. were considered as the best alternatives to C. echinata wood as sources of bow construction. The bows from the first two woods were already tested by professional musicians and their suitability was certified. The Diplotropis spp. wood also showed promising characteristics. Mezilaurus itauba and Astronium lecointei do not have the necessary properties for bows.

scholarly journals Applying Machine Strength Grading System to Round Timber Used in Hydraulic Engineering Works

Forests ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 281
Author(s):  
Michela Nocetti ◽  
Giovanni Aminti ◽  
C. Brand Wessels ◽  
Michele Brunetti
Keyword(s):  
Modulus Of Elasticity ◽  
Dynamic Modulus ◽  
Acoustic Velocity ◽  
Hydraulic Engineering ◽  
Raw Material ◽  
Dynamic Modulus Of Elasticity ◽  
Sawn Timber ◽  
Mechanical Selection ◽  
Round Timber ◽  
Selection Of

Round timber is often used for hydraulic engineering works, but the strength grading of round logs is not as well developed as that of sawn timber. The advantages of using defined strength classes, as well as the proper selection of the raw material, could be applicable to hydraulic works as well. In this study, the methods and rules developed for sawn timber were applied to the mechanical selection of oak round logs, paying particular attention to the issue of the simplicity of grading operations and the moisture content of the timber. Both the acoustic velocity and dynamic modulus of elasticity of oak logs were measured with different instruments before performing destructive bending tests; machine settings were derived for both properties and dry and wet grading operations were simulated to compare efficiency. The use of the dynamic modulus of elasticity makes machine grading more efficient. On the other hand, the use of acoustic velocity alone is feasible and makes the procedure much faster, even if wet grading resulted in very conservative estimations. The yields obtained were similar for lower grades, but to achieve higher strength classes, the dynamic modulus was preferable. For very fast and less expensive measurements, velocity could be considered an appropriate method, as an improvement over the use of unselected material.

scholarly journals Relationship among extractives, lignin and holocellulose contents with performance index of seven wood species used for bows of string instruments

IAWA Journal ◽  
2012 ◽  
Vol 33 (2) ◽  
pp. 141-149 ◽  
Author(s):  
Eduardo Luiz Longui ◽  
Iris Brémaud ◽  
Francides Gomes da Silva Júnior ◽  
Daniel Romeu Lombardi ◽  
Edenise Segala Alves
Keyword(s):  
Wood Species ◽  
Modulus Of Elasticity ◽  
Performance Index ◽  
Chemical Constituents ◽  
Wood Quality ◽  
Wood Properties ◽  
Bending Stiffness ◽  
Extractive Content ◽  
String Instruments ◽  
Caesalpinia Echinata

In this paper we investigate the influence of extractives, lignin and holocellulose contents on performance index (PI) of seven woods used or tested for violin bows. Woods with higher values of this index (PI = √MOE/ρ, where MOE is modulus of elasticity and ρ is density) have a higher bending stiffness at a given mass, which can be related to bow wood quality. Extractive content was negatively correlated with PI in Caesalpinia echinata, Handroanthus sp. and Astronium lecointei. In C. echinata holocellulose was positively correlated with PI. These results need to be further explored with more samples and by testing additional wood properties. Although the chemical constituents could provide an indication of quality, it is not possible to establish appropriate woods for bows solely by examining their chemical constituents.

scholarly journals Vibrational characteristics of four wood species commonly used in wood products

BioResources ◽  
2021 ◽  
Vol 16 (4) ◽  
pp. 7101-7111
Author(s):  
Wengang Hu ◽  
Shuang Li ◽  
Yan Liu
Keyword(s):  
Nondestructive Testing ◽  
Fundamental Frequency ◽  
Wood Species ◽  
Modulus Of Elasticity ◽  
Dynamic Modulus ◽  
Population Sample ◽  
Wood Products ◽  
Dynamic Modulus Of Elasticity ◽  
Vibrational Characteristics ◽  
Moduli Of Elasticity

The effects of the moisture content, density, and striking direction of a hammer on the vibrational characteristics, i.e., the fundamental frequency and dynamic modulus of elasticity, of four wood species, i.e., poplar (Populus tomentosa), mahogany (Swietenia mahagoni), beech (Fagus orientalis), and ash (Fraxinus excelsior), commonly used in wood products were investigated, aiming to provide basic evidence for the nondestructive testing of wood materials. The results showed that the effect of the wood species on the fundamental frequency, dynamic modulus of elasticity, and static modulus of elasticity was statistically significant. The dynamic moduli of elasticity of the four wood species were higher than the corresponding static moduli of elasticity. The effect of the striking direction on the dynamic modulus of elasticity was not significant, indicating that no matter where the hammer struck, i.e., radial and tangential surfaces, the fundamental frequency was essentially constant. Negative relationships were found between the fundamental frequency and the density and moisture when the data of the four wood species were viewed as a population sample. The vibrational characteristics of each wood species varied, which can be applied to the nondestructive testing of wood.

scholarly journals Woods with physical, mechanical and acoustic properties similar to those of Caesalpinia echinata have high potential as alternative woods for bow makers

CERNE ◽  
2014 ◽  
Vol 20 (3) ◽  
pp. 369-376 ◽  
Author(s):  
Eduardo Luiz Longui ◽  
Israel Luiz de Lima ◽  
Daniel Romeu Lombardi ◽  
José Nivaldo Garcia ◽  
Edenise Segala Alves
Keyword(s):  
Specific Gravity ◽  
Speed Of Sound ◽  
Modulus Of Elasticity ◽  
Sound Propagation ◽  
High Potential ◽  
Acoustic Properties ◽  
Caesalpinia Echinata

For nearly two hundred years, Caesalpinia echinata wood has been the standard for modern bows. However, the threat of extinction and the enforcement of trade bans have required bow makers to seek alternative woods. The hypothesis tested was that woods with physical, mechanical and acoustic properties similar to those of C. echinata would have high potential as alternative woods for bows. Accordingly, were investigated Handroanthus spp., Mezilaurus itauba, Hymenaea spp., Dipteryx spp., Diplotropis spp. and Astronium lecointei. Handroanthus and Diplotropis have the greatest number of similarities with C. echinata, but only Handroanthus spp. showed significant results in actual bow manufacture, suggesting the importance of such key properties as specific gravity, speed of sound propagation and modulus of elasticity. In practice, Handroanthus and Dipteryx produced bows of quality similar to that of C. echinata.

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

Akustika ◽  
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.

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

Buildings ◽  
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.

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

Holzforschung ◽  
2007 ◽  
Vol 61 (4) ◽  
pp. 414-418 ◽  
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.

Some Dynamic Properties of Rubber

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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