PSI - Issue 19

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Available online at www.sciencedirect.com Structural Integrity Procedia 00 (2019) 000 – 000 Structural Integrity Procedia 00 (2019) 000 – 000

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ScienceDirect

Procedia Structural Integrity 19 (2019) 224–230

Fatigue Design 2019 Effect of stress ratio on the fatigue fracture mechanism of adhesive single-lap joints: in case of GF/PP plates and an acrylic-based structural adhesive Hiroyuki Oguma a, *, Kimiyoshi Naito a a National Institute for Materials Science, Sengen 1-2-1, Tsukuba 3050047, Japan Applications of bonding technology have been expanded for lightweight structures and multi-material designs; however, the strength estimation and design method for bonded structures have not been fully established. New design concepts and standards related to strength and reliability are required from industries. In this work, fatigue tests under different stress ratio conditions and fracture surface observations were carried out to investigate the influence of the stress ratio on the fracture mechanism of adhesively bonded structures. Tested material was a glass-fiber-reinforced polypropylene composite plate, and adhesive was an acrylic-based structural adhesive. With single-lap joint specimens, fatigue tests were conducted using uniaxial electro-hydraulic fatigue testing system; frequency was f = 10 Hz, and stress ratios were R = −1, −0.5, 0.1, 0.5, 0.7, and 0.9. The effects of mean load were observed under higher stress ratio conditions, and fatigue strength at 10 7 (10 million) cycles dramatically deceased when the stress ratio was larger than 0.5. Fracture surface observations revealed correlation between the fatigue properties and fracture mechanism. Fatigue Design 2019 Effect of stress ratio on the fatigue fracture mechanism of adhesive single-lap joints: in case of GF/PP plates and an acrylic-based structural adhesive Hiroyuki Oguma a, *, Kimiyoshi Naito a a National Institute for Materials Science, Sengen 1-2-1, Tsukuba 3050047, Japan Abstract Applications of bonding technology have been expanded for lightweight structures and multi-material designs; however, the strength estimation and design method for bonded structur s have not been fully stablished. New design concepts a sta dards related to strength and reliability are required from industries. In this work, fatigue t sts under different stress ratio conditions and fracture surface observations were carried out to investigate the influ nce of the stress ratio on the fracture mechanism of dhesively bonded structures. Tested material was a glass-fiber-reinforced polypropylene composite plate, and adhesive was an acrylic-based structural adhesive. With single-lap joint specimens, fatigue tests were conducted using uniaxial electro-hydraulic fatigue testing system; frequency was f = 10 Hz, and stress ratios w re R = −1, −0.5, 0.1, 0.5, 0.7, and 0.9. The effects of mean load were observed under hi her stress ratio conditions, and fatigue strength at 10 7 (10 million) cycles dramatically decease when the stress ratio was larger than 0.5. Fracture surface observations revealed correlation between the fatigue properties and fracture mechanism. Abstract

© 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Fatigue Design 2019 Organizers. © 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Fatigue Design 2019 Organizers. © 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Fatigue Design 2019 Organizers.

Keywords: Multi-material design; Stress ratio; Adhesive joint; Fatigue; Structural adhesive; GFRP Keywords: Multi-material design; Stress ratio; Adhesive joint; Fatigue; Structural adhesive; GFRP

1. Introduction 1. Introduction

Fiber-reinforced plastics (FRPs) as represented by carbon fiber-reinforced plastics (CFRPs) with lightweight and high specific strength have been a focus of constant attention as structural materials for transport machinery [1-2]. Fiber-reinforced plastics (FRPs) as represented by carbon fiber-reinforced plastics (CFRPs) with lightweight and high specific strength have been a focus of constant attention as structural materials for transport machinery [1-2].

2452-3216 © 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Fatigue Design 2019 Organizers. 2452-3216 © 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Fatigue Design 2019 Organizers. * Correspon ing author. Tel.: +81-29-859-2616; fax: +81-29-859-2588. E-mail address: OGUMA.Hiroyuki@nims.go.jp * Corresponding author. Tel.: +81-29-859-2616; fax: +81-29-859-2588. E-mail address: OGUMA.Hiroyuki@nims.go.jp

2452-3216 © 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Fatigue Design 2019 Organizers. 10.1016/j.prostr.2019.12.024