Although adhesively bonded lap joint has already been widely applied in structures, the strength prediction of the joint is still a challenge. Among many parameters which affect the failure load of the lap joint, the adhesive layer thickness is a very important one. In this book, fracture mechanics is used to analyze the failure mechanism of the lap joint and evaluate the thickness effect on strength of the lap joint. For brittle material, constant effective fracture toughness is proposed for better strength prediction by considering of the non- singular stress term ahead of the crack tip. For ductile material, CTOA is proven to be insensitive to the constraining of the rigid boundaries and can be used as the failure criterion for fracture analysis. Both experimental and FEA simulation show that constant CTOA criterion well predicts the adhesive thickness effect on strength of the DCB specimens for Mode I fracture failure. The failure initiation mode of single lap joint is analyzed and the constant CTOA criterion is also proven to be capable to prediction the strength of single lap joint.

The Primary Adhesively Bonded Structure Technology (PABST) program was a U.S. Air Force sponsored program started in Feb. 1975 for the purpose of validating the use of adhesive bonding to join primary aircraft fuselage structural members. This paper will report on the analysis and component testing performed during the design development phase of the program, and the successful full-scale fuselage durability and damage tolerance test that was performed to four design lives. The goal of the program was to provide a savings of 20 percent on the acquisition and maintenance cost relative to mechanically fastened primary structure. Such effects as manufacturing quality, environment exposure, and a unique design criterion for bonded structure have significant impact on analysis methods. The initial development test program and results led to new testing techniques required for bonded joints to gain early design information. This is shown to be especially true for pressurized structure due to the unique behavior of metal crack propagation in this type structure. The full-scale fuselage test results and analysis correlation will be discussed as will the expanded purpose of the damage tolerance phase of this test and resulting demonstrations of crack containment within a stiffened skin panel under full cabin pressure.

A lot of recent developments have been made about adhesively bonded joints modeling using various methods of analysis. The increasing application of adhesives in industry is partly due to the increased sophistication and reliability of adhesive joints modeling. The book proposed intends to provide the designer with the most advanced stress analyses techniques in adhesive joints to reinforce the use of this promising bonding technique.

This book deals with the most recent numerical modeling of adhesive joints. Advances in damage mechanics and extended finite element method are described in the context of the Finite Element method with examples of application. The book also introduces the classical continuum mechanics and fracture mechanics approach and discusses the boundary element method and the finite difference method with indication of the cases they are most adapted to. At the moment there a no numerical technique that can solve any problem and the analyst needs to be aware of the limitations involved in each case.

Adhesively-bonded joints provide many advantages over conventional mechanical fasteners and are increasingly receiving attention as an alternative to mechanical joints in engineering applications. The traditional fasteners usually result in the cutting of fibers and hence the introduction of stress concentrations, both of which reduce structural integrity. By contrast, bonded joints are more continuous and have potential advantages of strength-to-weight ratio, design flexibility, and ease of fabrication. This book provides an overview of available analytical methods as well as numerical methods.

The aerospace industry lacks a validated, practical analysis method for the strength, durability, and damage tolerance evaluation of composite bonded joints. This paper presents the results of a combined strength and fracture analysis approach applied to typical bonded joint configurations found in rotorcraft composite structures. The analysis uses detailed 2-D non-linear finite element models of the local bondline. Strength-of-materials failure criteria are used to predict critical damage initiation loads and locations. A fracture mechanics approach is used to predict damage growth and failure under static and cyclic loads based on test data for static fracture toughness (GIc, GIIc) and crack growth rate (da/dN). Results are presented from the application of the analysis approach to two joint configurations: 1) a skin-stiffener T-joint and; 2) a bonded repair lap joint. The results show that the proposed approach can be used to predict critical failure modes, damage initiation loads and locations, crack and/or delamination stability, static strength, residual strength, and fatigue life. Discussion is also included on how this approach can be applied in damage tolerance evaluations of composite bonded joints.