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Types of specimens used for ultrasound velocity measurements in different orientations Slika 3. Vrste uzoraka rabljenih za ultrazvučna mjerenja brzina različitih smjerova
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ABSTRACT: Determining elastic constants of wood and wood-based composites of engineered materials is going to be necessary. Oriented strand board (OSB), as structural wood based panel plays a significant role in the building sector and the accessibility of such elastic constants of OSB is mostly limited. For this purpose, this study aimed at determ...
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... Wood-based panels are becoming more and more widely used in many areas of industrial production [1][2][3][4]. Their growing popularity is determined by numerous advantages over natural wood [5]. ...
... Their growing popularity is determined by numerous advantages over natural wood [5]. Wood-based materials are much cheaper, more homogeneous and isotropic, more resistant to fungi, insects, etc. [4,6,7]. Moreover, they allow the creation of flat surfaces of any dimensions-which is impossible in the case of solid wood. ...
The fact is that hundreds of holes are drilled in the assembly process of furniture sets, so intelligent drilling is a key element in maximizing efficiency. Increasing the feed rate or the cutting speed in materials characterized by a higher machinability index is necessary. Smart drilling, that is, the real-time adjustment of the cutting parameters, requires the evolution of cutting process variables. In addition, it is necessary to control and adjust the processing parameters in real time. Machinability is one of the most important technological properties in the machining process, enabling the determination of the material’s susceptibility to machining. One of the machinability indicators is the unit cutting resistance. This article proposes a method of material identification using the short-time Fourier transform in order to automatically adjust cutting parameters during drilling based on force signals, cutting torque and acceleration signals. In the tests, four types of wood-based materials were used as the processed material: medium-density fiberboard, chipboard, plywood board and high-pressure laminate. Holes with a diameter of 10 mm were drilled in the test materials, with variable feed rate, cutting speed and thickness of cutting layer. An innovative method for determining the value of unit cutting resistance was proposed. The results obtained were used to determine the machinability index. Based on the test results, it was shown that both the selected signal measures in the time and frequency domains and the unit cutting resistance are constant for a given material of a workpiece and do not depend on the drilling process parameters. In this article, the methodology is proposed, which can be used as an intelligent technique to support the drilling process to detect the material being machined using data from sensors installed on the machine tool. The work proposes the fundamentals for material identification based on the analysis of force signals and the magnitude of force derivatives. The proposed methodology shows effectiveness, which proves that it can be used in intelligent drilling processes. Hybrid wood-based material structures consisting of different materials are becoming more and more common in building structures for strength, economic and environmental reasons. Due to the difference in the machinability of interconnected materials, cutting parameters must be optimized in real time during machining. Currently, with the rapid development of Industry 4.0, the on-line identification of parameters is becoming necessary to improve the process flow in industrial reality. The proposed methodology can be used as an intelligent technique to support the drilling process in order to detect the material being processed using data from sensors installed on the machine tool.
... In contrast, the lower bound for the means of this study was around 3.3% higher than those of Aydın et al. (2007) reported for poplar. Because the P. canadensis is a naturally occurring hybrid of P. deltoides and P. nigra, the following densities of 390 kg/m 3 (Zahedi et al. 2020), 460 kg/m 3 (Hajihassani et al. 2018), 375 and 387 kg/m 3 (Altınok et al. 2009), 410 kg/m 3 (Bozkurt and Erdin 1989b), 420 kg/m 3 (Keleş 2021), 425 kg/m 3 (varied from 346 to 523) (Monteiro et al. 2019), and 450 kg/m 3 (Suleman 2015) should be taken into consideration. ...
The objective of this work was to evaluate the effect of growth ring number (specimens including 2, 4, and 6 rings from the bark) and growth ring width on elastic constants in the radial direction of Populus x canadensis, which has not been revealed before. The longitudinal (2.25 MHz) and transverse (1 MHz) ultrasonic waves were propagated to calculate the longitudinal (VRR) and shear (VRL, VLR, VTR, and VRT) wave velocities and used to determine the elasticity modulus (ER), and shear moduli (GRL and GRT). The average growth ring widths of specimens including 2, 4, and 6 rings were 17.0 mm, 17.8 mm, and 18.2 mm, respectively. According to the results, only VRL steadily increased with increased ring number, while other velocities fluctuated. The same fluctuations were observed for moduli except for GLR, which constantly increased with ring number. The influence of ring number on velocity was statistically significant only for VRL and VRT. However, all moduli were significantly affected by ring number. Linear regression statistics revealed that there were significant relations between the ring width and density, VRL, VLR, VRT, GRL, and GRT.
... The elastic constant of wood and its solid wood composite material is the quantity that characterizes the elasticity of the material (Yi 1996;Wang et al. 2014;Li et al. 2016;Li et al. 2020;Li et al. 2021;Li et al. 2021;Ponzo et al. 2021). Many researchers have studied the mechanical properties of wood (Ma 1996;Zhou et al. 2007;Cheng and Wang 2015;Wang et al. 2019;Felice et al. 2021), and static and dynamic methods have yielded results in testing its modulus of elasticity, shear modulus, and Poisson's ratio Wang et al. 2016;Zahedi et al. 2020;Li et al. 2021a,b;Tang et al. 2021; Wang and Ghanem 2021;Meng et al. 2021;Zhou et al. 2021). Many research studies used probabilistic methods to study the mechanical properties of materials (Fan and Shen 1992;Thomas 2003; Kumpenza et al. 2018;Peng et al. 2018; Wang and Roger 2021; Wang and Roger 2022). ...
A cantilever plate span-to-span patch method was proposed and demonstrated for dynamic testing of OSB Poisson’s ratio with high testing accuracy, simplicity, ease of implementation, and effectiveness. It is based on the patch method with zero transverse stress equal to the cantilever plate. Its effectiveness was verified by the four-point bending method and the patch strain gauge method with zero transverse stress. The simulation and theoretical analysis showed that the relative errors of OSB longitudinal and transverse Poisson’s ratios dynamically tested by the span-in patch method and the patch method with zero transverse stress were within ±3.8%. The OSB longitudinal and transverse Poisson’s ratios dynamically tested by the span-in patch method were in good agreement with those tested by the four-point bending method. Thus, the method is applicable to the cantilever plates with l/b= 5 to 6, b/h = 4 to 10, and l/b = 4, b/h = 7 to 10 for cantilevered plates, etc.
... Wood-based boards are becoming more and more widely used in many areas of industrial production [1][2][3][4]. Their growing popularity has been determined by their numerous advantages over natural wood [5]. ...
In contrast to metalworking there are no standardized or (at least) generally accepted, relative machinability tests for innovative or less known wood-based panels. The most reliable testing procedures are based on the use of a specialized, accurate system for measuring cutting forces and on conducting all tests in conditions that are similar to real industrial conditions (machine tool, cutting parameters etc.). However, the need for a more simplified testing procedure has often been voiced—not all scientists specializing in wood-based materials development have a machine tool comparable to one that can be found in a real furniture factory and piezoelectric force sensors at their unlimited disposal. To meet this need, the highly simplified, preliminary machinability test for wood-based boards in the case of drilling was developed and tried. The results of experimental research suggest that the simplified way of testing of relative machinability of wood-based boards (i.e., testing based on the photoelectric measurement of the time needed to make a 10 mm deep hole under constant feed force) can be a useful substitute of standard machinability testing procedure (based on accurate cutting forces measurements carried out in the standard industrial conditions). When verifying the simplified testing procedure, samples from each of the three basic groups of wood-based materials of substantially different internal structures (fiberboard, particleboard, and veneer boards) were tested. The relationship between significantly reliable and highly simplified machinability indexes turned out to be at a satisfactory level (R2 = 0.97 for particleboards and R2 = 0.95 for fiberboards or boards made of veneer or solid wood). The use of a simplified procedure can be especially pragmatic in case of any preliminary testing of innovative wood-based boards during the material development work.
Mechanical properties of engineering components are of importance in medical and industrial applications.
Ultrasonic nondestructive testing is one of the most effective methods for assessing the elastic properties of
materials. The purpose of this paper is to evaluate the elastic properties of components made by fused filament
fabrication (FFF) additive manufacturing process by using ultrasonic waves. This is accomplished by
fabricating a test specimen with a predetermined geometry from PLA polymer by FFF process. The ultrasonic
wave velocity is then measured in this test specimen along different directions. The elastic coefficients of the
specimen are then calculated from the measured wave velocities by assuming orthotropic structure for the
specimen. The engineering elastic coefficients, such as Young's modulus, Poisson's ratio, and shear modulus
are also found by inversing the elastic tensor. Considering that some of the measured elastic constants of this
material were almost identical, the hexagonal that was simpler than orthotropic. Based on the results, it can be
concluded that the sample has hexagonal anisotropy. The tensile testing results obtained from tensile samples
made from the same material were compared with ultrasonic test results and were in good agreement. Other
acoustic properties of this material such as sound attenuation and acoustic impedance were also measured and
discussed. It is concluded that the ultrasonic method is very efficient in measuring the elastic properties of
polymer components manufactured by FFF process and can be used for determination of changes in elastic
properties of the material due to variations in the process parameters.
Non-destructive techniques for characterizing materials in-service have been increasing in importance. Thus, it is relevant to assess the potential of non-destructive techniques for solid materials. This work aimed to determine the modulus of elasticity of Bertholletia excelsa wood using the particle image velocimetry technique and the ultrasound method to compare the results with the conventional methodology. For this purpose, samples of Bertholletia excelsa were made using a circular saw. The samples were evaluated for sound propagation to calculate the modulus of elasticity using ultrasound equipment. Subsequently, they were subjected to the compression parallel to grain test in a universal testing machine. The samples were marked and monitored during the loading session, with the repeated capture of images using a professional camera. The deformation values obtained were used to estimate the modulus of elasticity using the particle image velocimetry technique. The mean values of modulus of elasticity found were 17403 MPa for ultrasound, 15589 MPa for the particle image velocimetry technique, and 15333 MPa for the universal testing machine. The particle image velocimetry technique was considered to be statistically similar (Tukey α = 0,05) to the other methods tested. The linear coefficient of determination (R2) between the particle image velocimetry technique and the universal testing machine was 0,95, a high and satisfactory value. Thus, the particle image velocimetry technique and the ultrasound method are valid to estimate the modulus of elasticity of Bertholletia excelsa wood and possibly of woods with similar technological characteristics.
