Fibre losses during debranching and debarking of<i>Eucalyptus</i>pulp logs using a single-grip harvester

Merwe, Jaco-Pierre van der; Pulkki, Reino; Ackerman, Pierre

doi:10.2989/20702620.2015.1077416

Cited by 3 publications

(2 citation statements)

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“…Depending on the species, a threefold increase in drying rate was measured when comparing 0% debarked and 100% debarked wood (Defo and Brunette 2005;Röser et al 2011) • In-stand debarking can play a major role when considering forest health and spruce bark beetle (Ips typographus) prevention. This is especially the case for windthrow operations, as the layer between the bark and wooden body is the breeding habitat, which can be removed or destroyed by debarking the logs (Schroeder and Lindelow 2002;Thorn et al 2016;Irauschek et al 2017). The urgency for new spruce bark beetle preventative treatments is highlighted by the fact that within the Bavarian state forests, over 710,000 m 3 had to be harvested in 2017 as a result of spruce bark beetle infestations.…”

Section: Introductionmentioning

confidence: 99%

In-stand debarking with the use of modified harvesting heads: a potential solution for key challenges in European forestry

et al. 2019

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Modern forestry is increasingly confronted with challenges that appear with intensive forest management and the progression of the effects of climate change. The forestry sector is able to react to the changing conditions by adapting management plans, forest structure or planting tree species with a higher stress resistance. However, during stand management activities, silvicultural treatments and harvesting operations can have an impact on the further development of the remaining forest ecosystem. In Germany, the most widely used harvesting system for thinning operations is a single-grip harvester used for felling and processing trees followed by a forwarder for timber extraction from the machine operating trails to roadside. In this research project, debarking rollers and other modifications designed for Eucalyptus harvesting heads were tested on conventional harvesting heads for the first time to assess the possibility of adding debarking to mechanized forest operations under Central European conditions. Seven field tests with varying tree species, diameters and age classes, were established within German state forests in Lower Saxony and in Bavaria. These tests were repeated in both summer and winter seasons to evaluate the influence of associated tree sap flows on debarking quality. Three different harvesting heads were modified to assess the altered mechanical characteristics and setups. To assess debarking ability originating from head modifications, a photo-optical measurement system developed within the scope of the project was used. The results demonstrate that especially for summertime operations, simple modifications to currently used harvesting heads are able to provide an average debarking efficiency up to 90% depending on the modifications. Another key finding is that a negatively affected sap flow, experienced during wintertime operations, resulted in 46% lower debarking efficiency, while spruce bark beetle infestations only resulted in a wider spread of the variation. Additionally, the vertical position of the log within the tree proved to have an influence on debarking efficiency, resulting in 15% lower average debarking for butt logs and 9% for top logs as compared to middle logs. Since a debarking process requires the stem to be fed through the harvesting head on multiple occasions to remove bark, average harvesting productivity might be reduced by approx. 10% compared to productivity measured with conventional harvesting heads. Considering the results and the extent of the modifications, the system proved to be a potential addition to existing harvesting methods facing changing challenges in future forestry.

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Section: Introductionmentioning

confidence: 99%

In-stand debarking with the use of modified harvesting heads: a potential solution for key challenges in European forestry

et al. 2019

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“…With the use of forest harvesters in logging, the problems exposed in the work of traditional metal feeding rollers are becoming more obvious; the main reasons are surface damage and timber damage caused by the traditional feeding in the process of mechanical harvesting. 38 Jaco et al 39 investigated the damage of eucalyptus wood essence when using the harvester, compared it with the damage caused by artificial peeling and calculated the damage of eucalyptus wood essence and the loss of economic benefits. It was found that the essential causes of these damages are small contact surface and excessive pressure between the feeding rollers and logs.…”

Section: Introductionmentioning

confidence: 99%

The equivalent method of double V-wing honeycombs on the in-plane dynamic impact

Dian

Zhang

2021

Journal of Reinforced Plastics and Composites

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The double V-wing honeycomb can be applied in many fields because of its lower mass and higher performance. In this study, the volume, in-plane elastic modulus and unit cell area of the double V-wing honeycomb were analytically derived, which became parts of the theoretical basis of the novel equivalent method. Based on mass, plateau load, in-plane elastic modulus, compression strain and energy absorption of the double V-wing honeycomb, a novel equivalent method mapping relationship between the thickness–width ratio and the basic parameters was established. The various size factor of the equivalent honeycomb model was denoted as n and constructed by the explicit finite element analysis method. The mechanical properties and energy absorption performance for equivalent honeycombs were investigated and compared with hexagonal honeycombs under dynamic impact. Numerical results showed a well coincidence for each honeycomb under dynamic impact before 0.009 s. Honeycombs with the same thickness–width ratio had similar mechanical properties and energy absorption characteristics. The equivalent method was verified by theoretical analysis, finite element analysis and experimental testing. Equivalent honeycombs exceeded the initial honeycomb in performance efficiency. Improvement of performance and weight loss reached 173.9% and 13.3% to the initial honeycomb. The double V-wing honeycomb possessed stronger impact resistance and better load-bearing capacity than the hexagonal honeycomb under impact in this study. The equivalent method could be applied to select the optimum honeycomb based on requirements and improve the efficiency of the double V-wing honeycomb.

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Analyses on the roller structure of equivalent honeycombs for forest harvester under impact loading

Wang

2021

Composite Structures

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Fibre losses during debranching and debarking ofEucalyptuspulp logs using a single-grip harvester

Cited by 3 publications

References 13 publications

In-stand debarking with the use of modified harvesting heads: a potential solution for key challenges in European forestry

In-stand debarking with the use of modified harvesting heads: a potential solution for key challenges in European forestry

The equivalent method of double V-wing honeycombs on the in-plane dynamic impact

Analyses on the roller structure of equivalent honeycombs for forest harvester under impact loading

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