3rd INT. CONF. ON INTEGRATION OF DESIGN, ENGINEERING & MANAGEMENT FOR INNOVATION A.A. Fernandes, R.M. Natal Jorge, L. Patrício, A. Medeiros (Eds) Porto, Portugal, 4-6th September 2013 251 DESIGN AND DEVELOPMENT OF AN ADHESIVE JOINT TESTING APPARATUS FOR MIXED-MODE EVALUATION F.J.P. Chaves 1 , L.F.M. da Silva 2 ,M.F.M. de Moura 2 and D. Dillard 3 1 IDMEC- Pólo FEUP,Faculdade de Engenharia da Universidade do Porto, Rua Dr. Roberto Frias, 4200-465 Porto, Portugal chaves.filipe@fe.up.pt 2 DEMec,Faculdade de Engenharia da Universidade do Porto, Rua Dr. Roberto Frias, 4200-465 Porto, Portugal, lucas@fe.up.pt , mfmoura@fe.up.pt 3 Engineering Science and Mechanics Department, Virginia Tech, Blacksburg, VA 24061dillard@vt.edu KEYWORDS: Development, Design, Bonded joints, fracture characterization, mixed-mode I+II loading, in-plane mode mixity ABSTRACT: The present work is dedicated to the development and design of a load jig inspired in the proposed solution by Fernlund and Spelt in order to characterize fracture of bonded joints under mixed-mode I+II loading. The jig allows for easy alteration of the mode-mixity and permits covering the full range of mixed-mode I+II combinations. A data reduction scheme based on specimen compliance, beam theory and crack equivalent concept is proposed to overcome several difficulties inherent to the test analysis. The development was based in a design methodology using numerical validation based on experimental data obtained with a Dual Loading Frame from Virginia Tech. This methodology is presented and then validated with the experimental application of the jig. INTRODUCTION Bonded joints are being increasingly applied in structures involving risk, as is the case of the aeronautical, automotive, and civil infrastructure industries. The classical strength prediction based on stress or strain analysis may not be adequate in the presence of singularities which occur frequently in bonded joints. As a result, the development of sophisticated design criteria including progressive damage analysis is of fundamental importance. In this context cohesive zone modelling that combine stress-based criteria to simulate damage initiation and fracture mechanics criteria to deal with damage growth acquires special relevancy (Yang and Thouless 2001; Blackman, Hadavinia et al. 2003; Andersson and Stigh 2004; de Moura and Chousal 2006; Campilho, Moura et al. 2008). Fracture mechanics-based criteria require prior characterization of the joint under mixed-mode loading, since bonded joints in real applications often experience such situations. The objective of this work is to develop a new apparatus for the mixed-mode inspired in the test developed by Fernlund and Spelt (Fernlund and Spelt 1994). METHODOLOGY A design methodology based in simulation of the apparatus loading scheme matching the experimental data obtained was implemented and is explained. The loading jig consists primarily of two rigid beams linked to each other, to the specimen, and to a base plate (Figure 1). Different jig geometries can be achieved by altering the four distances, s 1 - s 4 , thereby varying the mode-mixity of the