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Hardness tester for wood - prototype instrumentation and validation of calibration results

Abstract

The mechanical property called hardness is largely used in material specifications, in mechanical and metallurgical studies and research and in the quality control of several kinds of materials. Specifically for timber, among the several mechanical properties used as tools for its quality control and technological potential, Janka hardness, which evaluate the relation between a superficial penetration force of a small steel sphere in wood and the indentation produced by such sphere, are highlighted. It is constituted by simple, quick and easily performed test, with good correlations with the compression parallel to grain strength, a high reference in structural classification for this material. More recently, international studies have reported the use of Brinell hardness for timber assessment. Besides the advantages previously mentioned for Janka hardness, the Brinell one would make it easier to perform the tests in field conditions, especially for its lower magnitude in terms of the involved loads. With this main objective, the Research Group Forest Products: technology and usage, from FCA/UNESP - Botucatu - Sao Paulo State, Brazil had developed an equipment for field evaluation of hardness in wood - Portable Hardness tester for wood - based on Brinell hardness, with the measurement of diameters of the indented calotte in wood. The functional and calibration tests of the equipment were performed with different species of native and reforested wood (traditional usage as ties in railways) allowing the establishment of regression correlations between the evaluated hardness and several other mechanical properties of the material. These tests already revealed the equipment great functionality, easy-to-use characteristics and low costs. In continuation with this research line, this project had the objective of studying the instrumentation of the Portable Hardness tester with accelerometers in order to automate the indentation evaluation in wood. Considering its opportunity, secondary objectives as the validation of regression equations established in the former program as well as the association to LSE - Structural Systems Laboratory, aiming the commercial production of the equipment will also be attended with this new experimental program. (AU)

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Scientific publications
(References retrieved automatically from Web of Science and SciELO through information on FAPESP grants and their corresponding numbers as mentioned in the publications by the authors)
DE ASSIS, ALBERT AUGUSTO; ALEXANDRE, ROGERIO PINTO; BALLARIN, ADRIANO WAGNER. Dynamic hardness of wood - measurements with an automated portable hardness tester. HOLZFORSCHUNG, v. 71, n. 5, p. 383-389, MAY 2017. Web of Science Citations: 1.

Please report errors in scientific publications list by writing to: cdi@fapesp.br.
Filed patent(s) as a result of this research project

EQUIPAMENTO E MÉTODO PARA MEDIÇÃO DE DUREZA DE MATERIAIS LIGNOCELULÓSICOS BR1020130241393 - Centro Estadual de Educação Tecnológica "Paula Souza" (CEETPS) ; Universidade Estadual Paulista (UNESP) . Adriano Wagner Ballarin; Albert Augusto de Assis; Roberto Antonio Colenci - September 2013, 20

APPARATUS AND METHOD FOR MEASURING THE HARDNESS OF LIGNOCELLULOSIC MATERIALS PCT/BR2014/000329 - Universidade Estadual Paulista (UNESP) . Adriano Wagner Ballarin; Albert Augusto de Assis; Roberto Antonio Colenci - September 2014, 12