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Visual and machine strength grading of European ash and maple for glulam application

  • Andriy Kovryga EMAIL logo , Philipp Schlotzhauer , Peter Stapel , Holger Militz and Jan-Willem G. van de Kuilen
Published/Copyright: March 22, 2019
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Abstract

Medium dense hardwoods (HWs) show higher tensile strength (TS) values than softwoods (SWs). These advantages cannot be utilised effectively because HW grading is not well developed. The aim of the present paper was to analyse the utilisation potential of European ash (Fraxinus spp.) and maple (Acer spp.) grown in Central Europe, which were graded by different methods. The visual grading characteristics of 869 HW boards were determined and the dynamic modulus of elasticity (MOEdyn) and X-ray attenuation (XRA) were measured by an industrial scanner. The specimens were subsequently tested in tension according to EN 408:2010 and according to German visual grading rules show strength values of 28 MPa and 30 MPa, respectively. Machine strength grading and for a combination of manually assessed boards and MOEdyn give rise to higher strength data. MOEdyn, in particular, results in lamella data with 62 MPa for ash and 42 MPa for maple. There is good agreement with recently presented HW tensile profiles. Machine grading with a multisensor system allows better strength prediction compared to the MOEdyn or visual strength grading. Best performance is achieved by a combined grading approach.

Award Identifier / Grant number: FKZ 22011913

Funding statement: This research was supported by the German Federal Ministry of Food and Agriculture (BMEL); Funder Id: 10.13039/501100005908, grant no.: FKZ 22011913.

  1. Author contributions: All the authors have accepted responsibility for the entire content of this submitted manuscript and approved submission.

  2. Employment or leadership: None declared.

  3. Honorarium: None declared.

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Supplementary Material

The online version of this article offers supplementary material (https://doi.org/10.1515/hf-2018-0142).


Received: 2018-06-21
Accepted: 2019-02-05
Published Online: 2019-03-22
Published in Print: 2019-07-26

©2019 Walter de Gruyter GmbH, Berlin/Boston

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