Ring Shake Research Articles

Analysis of Crack Expansion and Morphology of Cross-Laminated Timber Planar Shear Test

To describe the dynamic cracking process of the CLT vertical layer, the correlation between a load-displacement curve, specimen cracking, and planar shear failure mechanism of the CLT were explored. A three-point bending test and an improved planar shear test are used to evaluate the shear performance of the CLT. In this study, the load-displacement curve is recorded, the experimental part is synchronized with the video, the dynamic process of cracking of the vertical layer is observed and analyzed throughout the test. From the load-displacement curve, the image characteristics of the initial cracking and the sudden increase of the cracking of the specimen are summarized. The description results of the whole dynamic process of the CLT vertical layer cracking are analyzed by planar shear strength value, cracking phenomenon, and azimuth angle of cracking surface. The main conclusions show that the three-point bending test and the improved plain shear test can be used to test the plain shear strength of the CLT, with a difference of only 5.7%. The original crack and the new crack expansion account for 18.9% and 81.1% of the main cracking surface, respectively. And the vertical layer of the CLT specimen under three-point bending has three cracking morphologies, such as radial shake, ring shake, neither along with the radial shake nor along with the ring shake. The azimuth angle of the cracking surface of the CLT vertical layer under planar shear is quite consistent with the first main plane azimuth of the vertical layer of the CLT specimens under the three-point bending test and the shearing test. The shape in the cracking direction of the left half-span or the right half-span of the vertical layer of the specimen is similar to the Chinese character eight.

A tomographic approach to assessing the possibility of ring shake presence in standing chestnut trees

Ring shake is a widespread phenomenon affecting a great number of species of both softwood and hardwood and is found in trees grown in temperate and tropical climates. Chestnut (Castanea sativa Mill.) represents one of the most important hardwood timbers that is very often affected by ring shake. This defect seems to be the only real limit to the spread and use of chestnut wood worldwide on a scale closer to the availability of this wood. The aim of this study was to examine the potential of tomographic measurement as a non-destructive method for predicting the possibility of the presence of ring shake in standing chestnut trees. For this reason, the experiments were carried out in a chestnut coppice stand where one hundred chestnut standards were monitored using an acoustic tomographic device, and subsequently harvested by a local company and cross-sectioned corresponding to the acoustic tests. This work proposed an applied approach to predicting and determining wood quality (sound wood vs. defective wood) from tomographic data. The model, based on a non-linear approach, showed that sonic tomography can identify ring shake in a tree trunk without affecting its biological activity, overcoming the difficulties of predicting ring shake using only visual inspection.

Effect of ring shakes on mechanical properties of chestnut wood from a Greek coppice forest

Measurements of several mechanical and physical properties were carried out to detect possible variations between ring shaken and non-ring shaken logs or between different areas of wood from the same log (i.e., ring shaken log). Mature wood from the ring shake area had lower axial compression and hardness strength compared to mature wood away from ring shakes. Wood from ring shakes area had lower tangential swelling and precisely at the position of the shakes, the wood had a higher coefficient of anisotropy than the surrounding wood. The juvenile wood’s density from the ring shaken logs was higher compared to that of mature wood, as well as proportional limit and hardness strength. From comparisons between ring shaken and non-ring shaken log properties, the following results were determined: mature wood from any area (independent of the presence of shakes) of ring shaken logs had lower Modulus of Rupture, proportional limits, modulus of elasticity under static bending, axial compression, toughness, and ha...

Ring shake occurrence related to growth parameters and prediction model for its presence before felling

This work includes observations on chestnut logs at woodcutting areas, measurements of some growth characteristics and observations under microscope of chestnut wood cross sections with ring shakes. Some types of ring shakes were developed in logs with abnormalities, such as forking, double-pith, burls, pith eccentricity and elongated cross sections. The ring shake defect mainly occurred on logs from older trees with large diameters coming from orchards. On logs coming from coppice forests, where young chestnut trees were cut without reaching large diameter, ring shake rarely (and only on logs from trees cut after two rotations) occurred. Ring shakes rarely occur on juvenile wood. They usually occur on adult wood from logs of tree’s base. The presence of a wider ring followed by narrower rings or the width differentiation along the same ring of a cross section, consist of an area that ring shake is possible to be developed. Relations between age, log diameter and ring width heterogeneity with ring shake were determined. A prognostic statistical model based on logistic regression was developed giving success of up to 80% using age and diameter as estimators. Finally, microscopic observations revealed breakages of vessel members and fibers detachment either in the earlywood or in the latewood, in the area between two annual rings.

Frost Crack Impact on European Beech (<i>Fagus sylvatica</i> L.) Wood Quality

Frost crack represents one of the main defects which affect European beech wood quality. Therefore, the purpose of this paper is to improve the knowledge regarding both the impact of frost crack on European beech wood quality and the frost crack characteristics which affect wood quality. In order to do this, nineteen European beech trunks with frost crack have been studied. Each trunk has been cross-cut every 1 meter and the characteristics of frost crack and frost crack star-shaped heart have been measured in each cross-cut section. The defects which accompany frost crack have also been identified in each crosscut section. Moreover, the possibility of determining these defects using the IML RESIF500 – S Resistograph has been tested. The research has emphasized the existence of statistical correlations between frost crack star-shaped heart expansion, frost crack rib prominence and frost crack length. These correlations are expressed by multiple linear regressions. The presence of defects which affect wood structure leading to a decrease in penetration resistance can be determined accurately with the resistograph. Decay (in frost cracks older than 8 years) and ring shake have been identified as the most frequent defects which accompany frost crack. The measurements made on the frost cracks studied have been gathered in a graph which shows frost crack impact on European beech wood quality. The results obtained lead to the improvement of the criteria of European beech wood quality assessment by expanding the already existent knowledge and by identifying new aspects which may complete standing wood quality determination and sorting methods.

Frost Crack Impact on European Beech (<i>Fagus sylvatica</i> L.) Wood Quality

Frost crack represents one of the main defects which affect European beech wood quality. Therefore, the purpose of this paper is to improve the knowledge regarding both the impact of frost crack on European beech wood quality and the frost crack characteristics which affect wood quality. In order to do this, nineteen European beech trunks with frost crack have been studied. Each trunk has been cross-cut every 1 meter and the characteristics of frost crack and frost crack star-shaped heart have been measured in each cross-cut section. The defects which accompany frost crack have also been identified in each crosscut section. Moreover, the possibility of determining these defects using the IML RESIF500 – S Resistograph has been tested. The research has emphasized the existence of statistical correlations between frost crack star-shaped heart expansion, frost crack rib prominence and frost crack length. These correlations are expressed by multiple linear regressions. The presence of defects which affect wood structure leading to a decrease in penetration resistance can be determined accurately with the resistograph. Decay (in frost cracks older than 8 years) and ring shake have been identified as the most frequent defects which accompany frost crack. The measurements made on the frost cracks studied have been gathered in a graph which shows frost crack impact on European beech wood quality. The results obtained lead to the improvement of the criteria of European beech wood quality assessment by expanding the already existent knowledge and by identifying new aspects which may complete standing wood quality determination and sorting methods.

Empirical modelling of chestnut coppice yield for Cimini and Vicani mountains (Central Italy)

The prescription of stand rotation according to site conditions and economic targets requires yield information that expresses stand productivity under different site-classes. This is particularly relevant for the optimal management of chestnut coppices allowing the production of timber assortments sized differently. This paper reports a new yield model built for chestnut coppices of the Cimini and Vicani mountains (Central Italy), according to three site index classes. The model focuses on the development of stands after an intense thinning carried out at the ages of 13-14 years. The model is compared with two previous yield tables built for chestnut coppice forests living in the same area and including one site index class only. The study stresses the high productivity of chestnut coppices growing on the volcanic soils of Cimini and Vicani mountains and shows how the growth course following intense thinning allows to get stems with large mean volume at the end of rotation. In the light of the most recent studies on the causes of ring shake, i.e. the most relevant defect of chestnut wood, the negative consequences on timber quality originating from the current thinning regime are also outlined.

Physical and mechanical wood properties of ring-shaken chestnut (Castanea sativa) trees

Ring shake is a defect that strongly affects chestnut (Castanea sativa Mill.) use and its occurrence is known to be mainly related to mechanical stress within a tree; however, few investigations have compared the physico-mechanical properties of healthy and shaken trees. Hence, the aim of this study is to compare the density, compression strength, bending strength (MOR), and shrinkages between healthy and shaken trees in coppice stands. The investigation was carried out in the Lazio Region in central Italy in trees with a cambial age between 6 and 25 years. The results showed that shaken trees had lower mechanical strength and shrinkages than healthy ones and that the physico-mechanical parameters might be used to predict ring shake occurrence in a specific geographic area. Geographical location strongly affected the physico-mechanical properties of the chestnut wood, and this factor influenced ring shake occurrence. MOR value was assumed to be the parameter that could be applied at almost all study sites to distinguish between shaken and healthy trees. There was no difference between the shaken and healthy portions of a disk inside the same tree.

Structural analysis of lignin in chestnut wood by pyrolysis-gas chromatography/mass spectrometry

The goal of the study was to determine the percentage of lignin in chestnut wood and to characterize structurally this polymer by pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) according to a possible influence on ring shake defect. The sampling was performed in different sites of Lazio Region in Italy. Wood disks from trees with ring shake defect and without ring shake defect were selected and little amount of heartwood (1–2 g) sampled between 6th and 10th and between 11th and 15th annual growth ring were analyzed. The study allowed quantifying lignin content, which is in average 26% and syringyl/guaiacyl (S/G) ratio, which present an average value of 2.43. Belong the pyrolysis products of wood, the trees characterized by ring shake show a higher concentration of the phenol homosyringaldehyde respect to the healthy trees. There is not any evident difference in the products composition of pyrolysis in respect to trees’ age, especially the critical period of 12–14 years in which ring shake generally becomes more evident. The site of wood provenance is the higher factor of variability in the structure of lignin for many phenols.

Characterization of ring shake defect in chestnut (Castanea sativa Mill.) wood in the Lazio Region (Italy)

Summary The incidence of ring shake in chestnut wood (Castanea sativa Mill.) from eight sites (237 total trees) in the Lazio territory, in central Italy, was investigated. All the areas studied are coppice managed. The aim of this study was to increase knowledge of this defect through the measurement and classification of numerous indices. using analysis of variance and correlation analysis, age was found to be the principal factor affecting the ring shake defect, the incidence of which was highest in trees aged 30 years or over. The highest risk of splitting occurred in the 12- to 14-year-old age group, although cracking started with a certain intensity at an age of 7–8 years. Comparing trees of the same age (25–30), it can be seen that diameter was not strongly related to magnitude of defect, but it had the effect of moving the ring shake location outwards. Wood defects (star shake, injuries, double core and eccentricity of core) and stem defects (cortical cancer, epicormic branches, dead branches and bark cracking) were not significantly correlated with shake: indeed, only bark cracking and injuries seem to have a slight influence on ring shake risk.

External and internal growth parameters as potential indicators of shake in sweet chestnut (Castanea sativa Mill.)

Summary Growth measurements of individual stems in mature chestnut ( Castanea sativa Mill.) stands were taken prior to felling. Stem form, leaf phenology and wood structure were assessed in standing boles, mainly of coppice origin, at fi ve sites on contrasting soil types in Kent, south-east England. The majority of trees exhibiting ring and star shake were older, fl ushed later in the spring than sound trees and had shorter fl ushing periods than sound individuals. Traits such as the presence of epicormic shoots, bole curvature and spiral bark pattern were also signifi cantly correlated with shake. Increment cores revealed that shaken trees tended to have narrower rings, but larger diameter spring vessels compared with their sound counterparts. A logistic regression model confi rmed that shake could be modelled using relatively few parameters, including age, fl ushing phenology and the proportion of spring wood, whereas subjective scores based on bark characteristics alone were less reliable.

Ring shake in chestnut: Anatomical description, extent and frequency of failures

La roulure est un defaut du bois qui se produit tres frequemment dans le châtaignier (Castanea sativa Mill.). En examinant ce genre particulier de rupture il est visible au niveau anatomique que les separations qui se produisent dans le bois montrent des facies de rupture differents. Afin de disposer d'informations necessaires a la comprehension des causes qui menent au developpement de la roulure, une description microscopique et une quantification des differentes typologies de roulure ont ete effectuees sur 45 disques de châtaignier. Les resultats ont montre que parmi les divers types de roulure observes, la forme de rupture crack, c'est-a-dire la separation qui se developpe a travers les parois cellulaires des vaisseaux du bois initial, est la plus frequente et se presente principalement dans le bois fraichement abattu. Les observations microscopiques detaillees renforcent la conviction que le mecanisme conduisant a cette forme de rupture est lie a la faiblesse structurale du bois de châtaignier combinee avec les contraintes de croissance developpees dans la tige.

La cipollatura nel legno di castagno: un problema centrale per il rilancio della castanicoltura da legno di qualità | Ring shake in chestnut: a main problem for the resumption of quality chestnut wood cultivation

Ring shake poses one of the biggest problems for the management of chestnut coppices. New studies show that, within the framework of high-quality silviculture, it is possible to lessen the risk of ring shake. In this contribution we summarise important results from investigations carried out by the Sottostazione Sud delle Alpi of the WSL. In addition,possible measures resulting from the investigations are described to prevent and contain the risk of ring shake.

Is ray volume a possible factor influencing ring shake occurrence in chestnut wood?

Radially oriented ray tissue is important for regulating radial strength of wood. The present study was undertaken in order to assess whether radial rays influence ring shake occurrence in chestnut wood (Castanea sativa Mill.), a species very prone to ring shake. Ray volume fraction was measured on tangential samples from two sets of wood discs, either with or without ring shake, collected from three coppice stands in the southern part of the Swiss Alps. Our data indicate that ring shaken trees tend to exhibit higher ray volume than unshaken ones. This rather unexpected finding could be partly explained if biomechanical processes that control and determine the inner architecture of the tree are considered.

Ring shake in chestnut (Castanea sativa Mill.): State of the art

Too often chestnut wood (Castanea sativaMill.) becomes economically uninteresting because of the high risk of ring shake to which this species is prone. For more than twenty years chestnut ring shake has been the subject of studies undertaken in an effort to understand its underlying causes and mechanisms. Since not all aspects of the phenomenon have been sufficiently studied at the present time, ring shake has not yet been completely elucidated. However, it is possible to outline a general framework of the phenomenon and advance preliminary ideas on the causes that contribute to the development of this type of fracture. This article summarises the current state of knowledge, discusses the possible causes and proposes measures to reduce the risk of ring shake occurrence in chestnut . ring shake / Castanea sativa Mill. / wood / residual stresses / mechanical strength

RELATIONSHIP BETWEEN RING SHAKE INCIDENCE AND EARLYWOOD VESSEL CHARACTERISTICS IN CHESTNUT WOOD

This paper investigates whether in Chestnut (Castanea sativa Mill.) a relationship exists between anatomical features of earlywood vessels, which may contribute to weakening the wood, and the incidence of ring shake. The study compared two groups of 30 wood discs with and without ring shake, collected in three coppice stands in Southern Switzerland. Shake-prone stems are not characterised by more numerous and wider earlywood vessel lumina than the shake-free ones. Hence the hypothesis that ring shake is favoured by the weakening effect of earlywood cell lumina is rejected.

Ring shake and structural characteristics of a chestnut (Castanea sativa Miller) coppice stand in northern Piedmont (northwest Italy)

Dans un taillis de châtaignier de Torre Canavese (Turin, nord-ouest de l'Italie), sur une surface de 3 080 m 2 , on a analyse la structure du peuplement et, apres la coupe, la frequence et la distribution de la roulure des futs. Le but fixe etait observer la presence de la roulure des rejets, des souches et reserves et d'evaluer les eventuelles relations entre les donnees et celles qui caracterisent (structurellement et typologiquement) les tiges ou les souches individuellement ainsi que le peuplement entier du point de vue structurel et typologique. Les resultats indiquent que 96,2 % des reserves et 37,9 % des brins sont affectes par le defaut alors que seulement 51 % des souches presentent des rejets roules. La distribution des roulures dans le fut est concentree dans le tiers central sur le rayon et 50 % du defaut apparait sur les cernes des annees 1971, 1972 et 1973. La distribution des souches avec rejets roules n'est pas uniforme sur la parcelle.

Anatomy of Zones of Ring Shake in Eucalyptus Maculata

Zones of ring shake and the tangential surfaces of such fractures were examined using light microscopy. The shakes occurred predominantly in bands containing abnormally large amounts of axial parenchyma, traumatic parenchyma and/or vessels. These cells, of low Runkel ratio, usually separated by some form of transwall failure, exposing the cell lumen. The failure thus followed a path entailing minimal fracture of actual cell wall substance. The zones of abnormal tissue are probably formed in response to cambial injury and/or environmental stress.

The characterization of wetwood in western hemlock

One of the problem areas in the kiln drying of western hemlock lumber is the wide variation in final moisture content of the wood. This variation in moisture content is due to the presence of sinker or wetwood in the heartwood. The features of wetwood which differentiate it from the normal heartwood include higher specific gravity, higher extractives content, and lower permeability. The apparent higher specific gravity can be fully accounted for by the higher extractives content. The principial extractive is α-conidendrin. The wetwood in western hemlock often occurs together with ring shake and under these circumstances the white deposit on the shake surfaces is also α-conidendrin and not matairesinol, the substance usually associated with ring shake in western hemlock.

Ring shake in some hardwood species: The individual tree approach

AbstractThe formation of ring shake, a tangential separation of xylem tissue, is being studied in selected red oaks, white oaks, and black walnut. Previous studies have indicated that it is frequently necessary to make detailed analyses throughout one tree in order to evaluate correctly possible stages of development of this defect for the sample under investigation. In the present study, anatomical and chemical analyses both along the shake zone and for a normal zone within a black walnut tree are discussed. Anatomical investigations formed the basis for selection of xylem subdivisions for subsequent chemical analyses. The ring shake was tangentially confined to a single annual increment. This increment was radially subdivided into eight consecutive portions from earlywood through latewood. Each portion was used for determinations of specific gravity, extractives (ether, alcohol, hot water), methoxyl, and certain inorganics. Similar analyses were made on a “control” increment. The possible development of ring shake within the sample tree is presented in terms of resultant chemical and anatomical data.