Effect of Surface Roughness on the Shear and Tensile Strength of Hardwood Adhesive Joints: A Linear Elastic Model Andrea Cressoni De Conti 1,a and Cláudio De Conti 2,b 1 Campus Experimental de Rosana, UNESP – Univ. Estadual Paulista, 19.274-000, Rosana, SP, Brazil 2 Campus Experimental de Itapeva, UNESP – Univ. Estadual Paulista, 18.409-010, Itapeva, SP, Brazil a andrea@rosana.unesp.br, b conti@itapeva.unesp.br Keywords: Wood, Machining, Bonding, Tensile, Shear Strength, Elastic model Abstract. This study analyzed the bond line strength of Eucalyptus sp. specimens submitted to shear and perpendicular to grain tensile forces, depending on the wood quality machined surface. The woods plans were glued with two different polyvinyl acetate adhesives. The bonding surfaces were milling with three different feed speeds; 6.0, 11.0 and 15.0 m/min, corresponding to the feed per tooth of the cutting tool; 0.86, 1.57 and 2.14 mm, respectively. The specimen types corresponded to the standards according to ABNT NBR 7190/1997. The cutting plane considered only the geometry of milling due to the bond line joint strength. To explain the experimental results, was proposed a linear elastic model to machined wood and bond line. For the two adhesives used, the experimental results suggest that the greatest perpendicular to grain tensile strength and shear strength were obtained to bond surface machined with the intermediate feed speed namely 11 m/min, for others two feed speeds and in the shear strength case, was not observed a distinction between them, in the perpendicular to grain tensile strength, the feed speed 6.0 m/min presented a higher strength than the machined surface with 15.0 m/min. The model reproduces the behavior of the experimentally results obtained for the two tests, and so it can be readily applied as a tool for evaluate the machining feed speed and the bond line joint strength. Introduction One problem that happens with eucalyptus sawlog occurs during the growth of the tree because in this step it accumulates the named growth stresses [1-3] that were liberated in machining process [4], resulting in material lost. Adding to this effect, the eucalyptus wood has a considerable dimensional instability by retraction and swelling. Because of this, the eucalyptus sawlog has many finished quality product problems, in special if the wood had been used in structural element or like a furniture component [5,6]. Waste wood can be a solution for this problem, and use battens in battens boards it can reduce the waste and rationalize the sawlog productive process in the industry. An important aspect in the use of the waste wood is the necessity of the technology developments to make stable glued battens boards known Edge Glued Panel (EGPs) made with eucalyptus wood, and many questions must be answered like: How is the best species ? What kind of waste wood can be use ? How the materials should be machined and what feet speed it can be use? How the orientation of the rings can influence in the composition of the EGPs to make them more stable? What is the influence of the adhesive? How are the mechanics properties behave in the adhesive bond line? And others [5-13]. Among the many types of the adhesives, it was choice to use the polyvinyl acetate (PVA or PVAc). The polyvinyl acetate is a synthetic adhesive widely use to bond wood [14-16,19]. This work determined experimentally the shear strength and perpendicular to grain tensile strength in the bond line Eucalyptus sp. specimens, in function of the different feed speeds using in the finished machining surface of the battens that were glued with two PVA adhesives. An analytical model was proposed to analyze and predict the effects of machining on bond line wood strength with two types of PVA adhesives. Advanced Materials Research Vol. 1088 (2015) pp 750-757 Submitted: 19.10.2014 © (2015) Trans Tech Publications, Switzerland Accepted: 07.11.2014 doi:10.4028/www.scientific.net/AMR.1088.750 All rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of TTP, www.ttp.net. (ID: 201.42.152.223-27/01/15,15:25:23)