Advances in Modeling and Design of Adhesively Bonded Systems

S. Kumar, K. L. Mittal, S. Kumar, K. L. Mittal

• Publisher: Wiley-Scrivener
• Year: 2013
• Print ISBN: 9781118686379
• eBook ISBN: 9781118754078
• Edition: 1
• Topic: Technology & Engineering
• Subtopic: Materials Science
• Index: Technology & Engineering

The book comprehensively charts a way for industry to employ adhesively bonded joints to make systems more efficient and cost-effective

Adhesively bonded systems have found applications in a wide spectrum of industries (e.g., aerospace, electronics, construction, ship building, biomedical, etc.) for a variety of purposes. Emerging adhesive materials with improved mechanical properties have allowed adhesion strength approaching that of the bonded materials themselves. Due to advances in adhesive materials and the many potential merits that adhesive bonding offers, adhesive bonding has replaced other joining methods in many applications.

Containing nine articles written by world-renowned experts, the book deals with the advances in theoretical and computational modeling as well as the design and experimental aspects of adhesively bonded structural systems. Stress analysis and strength prediction of adhesively bonded structural systems, considering a range of material models under a variety of loading conditions, are discussed. Finite element modeling using macro-elements is elaborated on. Recent developments in modeling and experimental aspects of bonded systems with graded adhesive layers and dual adhesives are described. Simulation of progressive damage in bonded joints is addressed. A novel vibration-based approach to detect disbonding and delamination in composite joints is also discussed.

Readership
The book is central to a range of engineers including mechanical, reliability, construction and surface engineers as well as materials scientists who are engaged in the mechanics of structural adhesive joints. Industries that will use this book include aerospace, electronics, biomedical, automotive, ship building, and construction.

Chapter 1

Stress and Strain Analysis of Symmetric Composite Single Lap Joints Under Combined Tension and In-Plane Shear Loading

Jungmin Lee¹ and Hyonny Kim²

¹Samsung Mobile Display Inc., Yongin-City, Gyeonggi-Do, South Korea

²Department of Structural Engineering, University of California San Diego, La Jolla, California, USA

Abstract

An analysis is presented that predicts adhesive shear and peel stresses in adhesively bonded composite single lap joints. The single lap joint is under combined tension and in-plane shear loading, and accounts for moments induced by geometric eccentricity. These eccentricity moments primarily contribute to the peel stress. When shear, tension, and eccentricity moments are simultaneously applied to a joint, a combined multi-axial stress state (two shear stress components and peel) in the adhesive can be calculated. Example calculations presented in this paper show that the predicted stress profiles are well matched with finite element analysis (FEA) predictions. The von Mises yield criterion is applied to predict the elastic limit of the adhesive for a lap joint under combined loading. This approach allows the calculation of an envelope of combined loading conditions under which the joint is expected to behave elastically.

Keywords: Adhesive bonding, combined load, multiaxial stress, peel, elastic limit

1.1 Introduction

A closed-form model is derived that predicts shear and peel stress profiles in adhesively bonded symmetric single lap joints under multiaxial loading: in-plane shear load N_xy and in-plane tension load N_x. Edge moments induced from the geometric eccentricity have been accounted for when formulating shear and peel governing equations corresponding to in-plane tension load N_x. Shear stress components are computed based on shear-lag assumptions and peel stress is obtained from a beam on elastic foundation (BOEF) approach.

Classical analyses, based on shear-lag, have been previously developed to predict only the adhesive shear stress in bonded joints of uniform bondline thickness for a symmetric joint subjected to tension loading only [1, 2]. Improvements to the classical model include predicting peel stress and edge moments in single lap joints [3–6], accounting for plasticity in the adhesive prior to failure [7, 8], and allowing for transverse shear deformation of the symmetric adherends [9]. Delale et al. [10] extended Goland and Reissner’s approach for symmetric joints by formulating the adhesive shear stress equation to account for asymmetric adherends. Similar approaches for the asymmetric joints are presented by Yang and Pang [11], Bigwood and Crocombe [12], and Wu et al. [13].

Adhesively bonded lap geometries loaded by in-plane shear have been discussed by Hart-Smith [2], van Rijn [14], and the Engineering Sciences Data Unit [15]. The authors of these works indicate that shear loading can be analytically accounted for by simply replacing the adherend Young’s modulus in the tensile loaded lap joint solution with the respective adherend shear modulus. This assumption is valid only for simple cases with one-dimensional loading, whereas in-plane shear loaded joints are generally two- or three-dimensional. A closed-form solution for combined multiaxial loading is presented by Mortensen and Thomson [16], although the boundary conditions are treated as input parameters and the solution is not validated by FEA or experiment. To the authors’ best knowledge, there are no closed-form analytical works that are applicable to symmetric joints under combined shear loading and tension loading with self-induced eccentricity moments. Previous work by Lee and Kim [17] predicts adhesive shear and peel stress profiles for a generally asymmetric joint and includes the effects of eccentricity moments. Kim and Kedward [18] have computed failure envelopes for combined tension and shear but did not account for adherend bending and peel stress. Mathias et al. [19] and Adams and Peppiatt [20] have also developed stress analyses p...

Table of contents

• Cover
• Half Title page
• Title page
• Copyright page
• Preface
• Acknowledgements
• Chapter 1: Stress and Strain Analysis of Symmetric Composite Single Lap Joints Under Combined Tension and In-Plane Shear Loading
• Chapter 2: Finite Element Modeling of Viscoelastic Behavior and Interface Damage in Adhesively Bonded Joints
• Chapter 3: Modeling of Cylindrical Joints with a Functionally Graded Adhesive Interlayer
• Chapter 4: A Simplified Stress Analysis of Bonded Joints Using Macro-Elements
• Chapter 5: Simulation of Bonded Joints Failure using Progressive Mixed-Mode Damage Models
• Chapter 6: Testing of Dual Adhesive Ceramic-Metal Joints for Aerospace Applications
• Chapter 7: Modelling of Composite Sandwich T-Joints Under Tension and Bending
• Chapter 8: Strength Prediction Methods for Adhesively Bonded Lap Joints between Composite–Composite/Metal Adherends
• Chapter 9: Interface Failure Detection in Adhesively Bonded Composite Joints Using a Novel Vibration-Based Approach