scholarly journals Ultrasonic technique for evaluation of initial stadium of wood degradation in exterior conditions without ground contact

2016 ◽  
Vol 62 (3) ◽  
pp. 164-168 ◽  
Author(s):  
Miloš Pánek ◽  
Kamil Trgala
Keyword(s):  
Black Locust ◽  
Abiotic Factors ◽  
Douglas Fir ◽  
Ground Contact ◽  
Ultrasonic Technique ◽  
Surface Cracks ◽  
Wood Degradation ◽  
The Czech Republic ◽  
Content Change ◽  
Non Destructive

Abstract The experiment evaluate the possibility of using non-destructive measure techniques of the mechanical properties of wood using ultrasonic to determine the initial stages of degradation by biotic and abiotic factors in the outdoors without ground contact. Nine tree species were tested: spruce, pine, Douglas fir, larch, oak, black locust, maple, poplar and alder. Test specimens were exposed to the exterior according to EN 927-3, Prague-Suchdol in the Czech Republic. Measuring changes in velocity of ultrasonic using the apparatus Ultrasonic Timer and moisture content change were measured after 1, 2, 3, 4 and 6 months. Certain ways of detecting the initial stages of damage have been demonstrated to trees oak, larch and spruce. The initial stages of damage by molds at non-durable maple, alder and poplar had not a clear impact on the decrease in the speed of ultrasonic, as well as hairline surface cracks at the Douglas fir.

Laser-Generated Ultrasonic Technique for Inspecting Delamination in CFRP

2006 ◽  
Vol 321-323 ◽  
pp. 968-971
Author(s):  
Won Su Park ◽  
Sang Woo Choi ◽  
Joon Hyun Lee ◽  
Kyeong Cheol Seo ◽  
Joon Hyung Byun
Keyword(s):  
High Frequency ◽  
Ultrasonic Method ◽  
Piezoelectric Sensor ◽  
Frequency Component ◽  
Guided Wave ◽  
Center Frequency ◽  
High Frequency Component ◽  
Ultrasonic Technique ◽  
Non Destructive Evaluation ◽  
Non Destructive

For improving quality of a carbon fiber reinforced composite material (CFRP) by preventing defects such as delamination and void, it should be inspected in fabrication process. Novel non-contacting evaluation technique is required because the transducer should be contacted on the CFRP in conventional ultrasonic technique during the non-destructive evaluation and these conventional contact techniques can not be applied in a novel fiber placement system. For the non-destructive evaluation of delamination in CFRP, various methods for the generation and reception of laser-generated ultrasound are applied using piezoelectric transducer, air-coupled transducer, wavelet transform technique etc. The high frequency component of laser-generated guided wave received with piezoelectric sensor disappeared after propagating through delamination region. Air-coupled transducer was tried to be adopted in reception of laser-generated guided wave generated by using linear slit array in order to generate high frequency guided wave with a frequency of 1.1 MHz. Nevertheless, it was failed to receive high frequency guided wave in using air-coupled transducer and linear slit array. Transmitted laser-generated ultrasonic wave was received on back-wall and its frequency was analyzed to establish inspecting technique to detect delamination by non-contact ultrasonic method. In a frequency spectrum analysis, intensity ratio of low frequency and center frequency was approvable parameter to detect delamination.

scholarly journals Ultrasonic Non-Destructive  Testing of Fibre Reinforced  Composites

2021 ◽  
Author(s):  
◽  
Matthew Thomson
Keyword(s):  
Experimental Work ◽  
Rayleigh Waves ◽  
Ultrasonic Waves ◽  
Reinforced Composites ◽  
Surface Cracks ◽  
Non Destructive Testing ◽  
Destructive Testing ◽  
Reinforced Composite ◽  
Non Destructive ◽  
Fibre Reinforced Composites

<p>This thesis focuses on the application of high frequency ultrasound as a tool for performing non-destructive testing for pultruded fibre reinforced composite (FRC) rods. These composite rods are popular in the manufacturing, construction and electrical industries due to their chemical, electrical and strength properties. Such FRCs are manufactured on automated production lines that operate day and night. Non-destructive testing techniques are desired to quickly and accurately detectmanufacturing flaws such as coating thickness irregularities and surface cracks. Layers and cracks can present as large changes in acoustic impedance and will strongly reflect ultrasonic waves. Combined with their low cost, east of use and absense of potentially harmful radiation, ultrasound has proven popular worldwide for Non-Destructive Testing. Finite Element Analysis (FEA) was employed to investigate the propagation of ultrasonic waves through layers of material to simulate a thickness measurement and the ability of ultrasound to measure thicknesses was proven. Experimental work was conducted on two fibre reinforced composite samples with varying thickness coatings of plastic and paint. The thickness was measured accurately using immersion transducers at 50MHz and a resolution of 20μm was attained through the use of matched filtering techniques. Surface acoustic waves, particularly Rayleigh waves were investigated using FEA techniques so that the generation, scattering and detection of such waves was understood. This lead to the development of methods for detecting surface cracks in glass using Rayleigh waves and these methods were successfully used in experimental work. Wave propagation in fibre reinforced composites was modelled and experimentally investigated with the results confirming theoretical expectations. Finally a Rayleigh wave was launched onto a fibre reinforced composite sample however the amount of energy leakage into the water was so great, due to the acoustic impedance of water, the detection of the wave was prevented. The conclusion reached was that an immersion setup was not appropriate for launching a travelling Rayleigh wave.</p>

Review on the Development of Non-Destructive Testing Based on Laser Ultrasonic Technique

2014 ◽  
Author(s):  
Yuanfeng He ◽  
Wenwu Zhang
Keyword(s):  
Quality Control ◽  
Optical Method ◽  
Vibration Signal ◽  
Quality Inspection ◽  
Ultrasonic Technique ◽  
Non Destructive Testing ◽  
Destructive Testing ◽  
Laser Ultrasonic ◽  
Ultrasonic Technology ◽  
Non Destructive

Development of industry demands better performance of equipments and devices than ever. The property of material used to produce the equipments is the precondition to ensure the quality. As equipments are usually required to be integral during the quality inspection, non-destructive testing (NDT) plays an increasingly import role in modern industry quality control. Different NDT methods are introduced and analyzed. The mechanism of ultrasonic exciting is described. After the ultrasonic is excited, the vibration signal can be detected by transducer or optical method which are then illustrated. In the section of development of laser ultrasonic technology, contributions made by various researchers in theoretic development, experiment, simulation and application are introduced and the corresponding content of the researches as well. The conclusion and the outlook of laser ultrasonic technique is made at the last.

scholarly journals Some aspects of alder decline along the Lužnice River

2012 ◽  
Vol 51 (No. 9) ◽  
pp. 381-391 ◽  
Author(s):  
I. Vyhlídková ◽  
D. Palovčíková ◽  
M. Rybníček ◽  
P. Čermák ◽  
L. Jankovský
Keyword(s):  
Czech Republic ◽  
Tree Ring ◽  
Fungal Pathogen ◽  
Abiotic Factors ◽  
Health Condition ◽  
Causal Agent ◽  
Direct Effects ◽  
Biotic Factor ◽  
The Czech Republic ◽  
Secondary Activation

Alder decline along watercourses is one of the marked manifestations of tree decline in the Czech Republic. Local decline of alder trees is documented in the Czech Republic for about 15 years. The aim of this paper is to evaluate causes of alder decline and assess health conditions of other species of riparian stands at 2 localities on the medium reach of the Lužnice River. Effects were studied of abiotic and biotic stressors on the health condition of tree species. No fungal pathogen was found in tissues of declining alders which would be present in all trees and which could be considered to be the main causal agent of the decline. Even an occurrence of the causal agent of alder decline named alder-Phytophthora has not been proved. Tree-ring analyses demonstrated decreasing trends of an increment in alders; however, an abiotic or biotic factor showing direct effects on the fluctuation of tree ring dimensions has not been positively determined. A marked role in the alder decline is demonstrated particularly by abiotic factors accompanied by the secondary activation of some pathogens. Generally, the phenomenon can be named as polyetiologic decline.

scholarly journals Evaluation of the provenance plot “Hrubá Skála” (Northern Bohemia) with grand fir at the age of 36 years

2017 ◽  
Vol 63 (No. 2) ◽  
pp. 75-87 ◽  
Author(s):  
Fulín Martin ◽  
Novotný Petr ◽  
Podrázský Vilém ◽  
Beran František ◽  
Dostál Jaroslav ◽  
...  
Keyword(s):  
Czech Republic ◽  
Norway Spruce ◽  
Coastal Region ◽  
Tree Height ◽  
Douglas Fir ◽  
Stem Volume ◽  
Silver Fir ◽  
The Czech Republic ◽  
The North ◽  
Oregon Cascades

The article aims to evaluate the research provenance plot established in 1980 in locality No. 214 – Hrubá Skála (in the north of the Czech Republic), where nine provenances of grand fir (Abies grandis (Douglas ex D. Don) Lindley) provided in the framework of the International Union of Forest Research Organizations project, and one provenance of grand fir, Norway spruce, silver fir and Douglas-fir from a standard commercial source are tested. We present the results of tree height, stem DBH, stem volume production and health status after 36 years. The results correspond with similar experiments in the Czech Republic and abroad and suggest that grand fir provenances from Vancouver Island (British Columbia, Canada) and the Washington (USA) State coastal region show the best production features, while the Oregon Cascades, Idaho and Montana provenances grow more slowly. Comparison with other tree species indicates that the production of grand fir at the investigated age exceeds the production of both Norway spruce and silver fir, and equalizes or gently exceeds even Douglas-fir.

scholarly journals Economic Impact of Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco) production in the Czech Republic

2014 ◽  
Vol 60 (No. 7) ◽  
pp. 297-306 ◽  
Author(s):  
K. Pulkrab ◽  
M. Sloup ◽  
M. Zeman
Keyword(s):  
Czech Republic ◽  
Economic Impact ◽  
Pseudotsuga Menziesii ◽  
Tree Species ◽  
Economic Effect ◽  
Douglas Fir ◽  
European Countries ◽  
Natural Conditions ◽  
The Czech Republic ◽  
Forest Production

The article addresses the issues of Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco) production in the Czech Republic (CR). Our analysis shows that the tree species can occupy 149,616&ndash;163,713 ha in the CR (with respect to ecological limits set by the Czech legislation). The potential economic effect expressed by the gross yield of forest production might be higher by 27&ndash;30 million EUR&middot;yr<sup>&ndash;1</sup>.&nbsp; The results of the analysis support the forest owners&rsquo; interest to extend Douglas-fir production in the CR, similarly like it has been extended systematically in all European countries where natural conditions allow. &nbsp;

scholarly journals Testing of germination of spruce, pine and larch seed after 10 years from collection

2014 ◽  
Vol 60 (No. 12) ◽  
pp. 540-543
Author(s):  
I. Tomášková ◽  
J. Vítámvás ◽  
J. Korecký
Keyword(s):  
Czech Republic ◽  
Picea Abies ◽  
Pinus Sylvestris ◽  
Tree Species ◽  
Abiotic Factors ◽  
Forest Tree ◽  
Germination Capacity ◽  
The Czech Republic ◽  
Germination Energy ◽  
Seed Ageing

:Germination capacity and germination energy are usually the most frequently used quantitative parameters of forest tree seed. With seed ageing both parameters decreased and the rate of the collapse is given by tree species, age of tree and its seed and biotic and abiotic factors. Relatively little attention has been paid to the age of seed. As it was found, the longevity of the main tree species remained relatively high, and spruce (Picea abies [L.] Karsten and pines (Pinus sylvestris L.) from the investigated areas across the Czech Republic maintained minimally one third of germination capacity or germination energy during the 10 years with the exception of larch (Larix decidua Mill.) where germination capacity decreased almost to zero after 10 years. Although the germination energy and germination capacity decreased significantly, it is possible to use the seed in the case of shortage of the seed of better quality. &nbsp;

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