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Licensed Unlicensed Requires Authentication Published by De Gruyter January 25, 2017

Dynamic hardness of wood – measurements with an automated portable hardness tester

Albert Augusto de Assis ORCID logo EMAIL logo , Rogério Pinto Alexandre ORCID logo and Adriano Wagner Ballarin ORCID logo
From the journal Holzforschung


A research group on forest products from School of Agriculture – Sao Paulo State University. Brazil developed a portable hardness tester for wood, which is based on a displacement transducer and an embedded electronic processor for dynamic evaluation of hardness. This paper presents the results of calibration tests of the equipment, carried out on seven species of Eucalyptus. A new methodology for dynamic hardness calculation has been introduced, which relays on the reaction force of the indentation, while the measurements of indentation depth are performed under load. A moderate to strong linear correlation to Janka hardness and its variations were found. This new approach avoids the classical problems of Brinell hardness test in terms of “sinking-in” (causing diffuse edges) and elastic recovery of the indentation.


The authors express their gratitude for the financial support given by FAPESP – Sao Paulo Research Foundation for the development of this project (08/08414-0).


American Society for Testing Materials (1987) ASTM D1037-78. Hardness Modulus Test – Number of Penetrations, 234.Search in Google Scholar

Associação Brasileira de Normas Técnicas (1997) NBR 7190. Projeto de estruturas de madeira. (in Portuguese).Search in Google Scholar

Ballarin, A.W., Almeida, P., Lara Palma, H., Colenci, R. (2010) Portable hardness tester for timber classification. In: WCTE 2010 – World Conference on Timber Engineering, Trentino, Italy. p. 8.Search in Google Scholar

Ballarin, A.W., Almeida, P., Lara Palma, H. (2012) Estimating hardness of eucalyptus wood with a portable hardness tester. In: WCTE 2012 – World Conference on Timber Engineering, Auckland. p. 4.Search in Google Scholar

Ballarin, A.W., Assis, A.A., Lara Palma, H. (2013) Development of a portable hardness tester for wood using displacement transducer. In: 18th International Nondestructive Testing and Evaluation of Wood Symposium, Madison, WI, USA. p. 6.Search in Google Scholar

Colenci, R.A. (2002) Mechanical qualification of wood for railroad crossties. Dissertation (MSc in Agronomy/Energy in Agriculture. College of Agricultural Sciences – Sao Paulo State University, Botucatu. p. 90. (in Portuguese)Search in Google Scholar

Colenci, R.A. (2006) Development of equipment to field-evaluation of hardness in wood for railroad cross ties. PhD Thesis, College of Agricultural Sciences – Sao Paulo State University, Botucatu. (in Portuguese).Search in Google Scholar

Doyle, J. (1980) The hardness of wood. PhD Thesis, University of Canterbury, Christchurch, New Zealand.Search in Google Scholar

Doyle, J., Walker, J.C.F. (1985a) Indentation hardness of wood. Wood Fiber Sci. 17:369–376.Search in Google Scholar

Doyle, J., Walker, J.C.F. (1985b) Indentation of wood by wedges. Wood Sci. Technol. 19:47–55.10.1007/BF00354752Search in Google Scholar

Dubovský, J., Rohanová, A. (2007) Static and dynamic hardness of chosen wood species. In: Proceedings of the 2nd Int. Scientific Conference Woodworking Technique, Zalesina, Croatia. Faculty of Forestry, University of Zagreb. p. 6.Search in Google Scholar

Grekin, M., Verkasalo, M. (2013) Variations in and models for Brinell hardness of Scots pine wood from Finland and Sweden. Balt. For. 19:128–136.Search in Google Scholar

Hansson, L., Antti, A.L. (2006) The effect of drying method and temperature level on the hardness of wood. J. Mater. Process Techn. 171:467–470.10.1016/j.jmatprotec.2005.08.007Search in Google Scholar

Helińska-Raczkowska, L., Moliński, W. (2003) The effect of the Janka ball indentation depth on the hardness number determined for selected species. Folia Forest. Polonica. 34:27–36.Search in Google Scholar

Heräjärvi, H. (2004). Variation of basic density and Brinell hardness within mature Finnish Betula pendula and B. pubescens stems. Wood Fiber Sci. 36:216–227.Search in Google Scholar

Hirata, S., Ohta, M., Honma, Y. (2001) Hardness distribution on wood surface. J. Wood Sci. 47:1–7.10.1007/BF00776637Search in Google Scholar

Holmberg, H. (2000) Influence of grain angle on Brinell hardness of Scots pine (Pinus sylvestris L.). Holz Roh Werkst. 58:91–95.10.1007/s001070050392Search in Google Scholar

Konnerth, J., Eiser, M., Jäger, A., Bader, T.K., Hofstetter, K., Follrich, J., Ters, T., Hansmann, C., Wimmer, R. (2010) Macro- and micro-mechanical properties of red oak wood (Quercus rubra L.) treated with hemicellulases. Holzforschung. 64:447–453.10.1515/hf.2010.056Search in Google Scholar

Lehringer, C., Koch, G., Adusumalli, R.-B., Mook, W.M., Richter, K., Militz, H. (2011) Effect of Physisporinus vitreus on wood properties of Norway spruce. Part 1: Aspects of delignification and surface hardness. Holzforschung. 65:711–719.10.1515/hf.2011.021Search in Google Scholar

Lewis, W.C. (1968) Hardness modulus as an alternative measure of hardness to the standard Janka ball for wood and wood-base materials. Forest Prod. Lab. Madison, WI, USA.Search in Google Scholar

Meyer, L., Brischke, C., Welzbacher, C.R. (2011) Dynamic and static hardness of wood: method development and comparative studies. Int. Wood Prod. J. 2:5–11.10.1179/2042645311Y.0000000005Search in Google Scholar

Niemz, P., Stübi, T. (2000) Investigations of hardness measurements on wood based materials using a new universal measurement system. In: Proceedings of the symposium on wood machining, properties of wood and wood composites related to wood machining, BOKU – University of Natural Resources and Applied Life Sciences, Vienna, Austria. pp. 51–61.Search in Google Scholar

Swaczyna, I., Kedzierski, A., Tomusial, A., Cichy, A., Rozanska, K., Policinska-Serva, A. (2011) Hardness and wear resistance tests of the wood species most frequently used in flooring panels. Ann. WULS-SGGW, Forestry Wood Techn. 76:82–87.Search in Google Scholar

Received: 2016-8-29
Accepted: 2016-12-28
Published Online: 2017-1-25
Published in Print: 2017-5-1

©2017 Walter de Gruyter GmbH, Berlin/Boston

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