Residual Strength Analyses of Riveted Lap-splice Joints


Book Description

The objective of this paper was to analyze the crack-linkup behavior in riveted lap-splice joint panels with small multiple-site damage (MSD) cracks at several adjacent rivet holes. Analyses are based on the STAGS (STructural Analysis of General Shells) code with the critical crack-tip-opening angle (CTOA) fracture criterion. To account for high constraint around a crack front, the "plane strain core" option in STAGS was used. The importance of modelling rivet flexibility with fastener elements that accurately model load transfer across the joint is discussed. Fastener holes are not modeled but rivet connectivity is accounted for by attaching rivets to the sheet on one side of the cracks that simulated both the rivet diameter and MSD cracks. Residual strength analyses made on 2024-T3 alloy (1.6-mm thick) riveted lap-splice joints with a lead crack and various size MSD cracks were compared with test data from Boeing Airplane Company. Analyses were conducted for both restrained and unrestrained buckling conditions. Comparison of results from these analyses and results from lap-splice-joint test panels, which were partially restrained against buckling indicate that the test results were bounded by the failure loads predicted by the analyses with restrained and unrestrained conditions.




Residual Strength Analyses of Riveted Lap-Splice Joints


Book Description

The objective of this paper was to analyze the crack-linkup behavior in riveted-stiffened lap-splice joint panels with small multiple-site damage (MSD) cracks at several adjacent rivet holes. Analyses are based on the STAGS (STructural Analysis of General Shells) code with the critical crack-tip-opening angle (CTOA) fracture criterion. To account for high constraint around a crack front, the "plane strain core" option in STAGS was used. The importance of modeling rivet flexibility with fastener elements that accurately model load transfer across the joint is discussed. Fastener holes are not modeled but rivet connectivity is accounted for by attaching rivets to the sheet on one side of the cracks that simulated both the rivet diameter and MSD cracks. Residual strength analyses made on 2024-T3 alloy (1.6-mm thick) riveted-lap-splice joints with a lead crack and various size MSD cracks were compared with test data from Boeing Airplane Company. Analyses were conducted for both restrained and unrestrained buckling conditions. Comparison of results from these analyses and results from lap-splice-joint test panels, which were partially restrained against buckling indicate that the test results were bounded by the failure loads predicted by the analyses with restrained and unrestrained conditions.Seshadri, B. R. and Newman, J. C., Jr.Langley Research CenterLAP JOINTS; RIVETED JOINTS; STRUCTURAL ANALYSIS; RIVETS; CRACKS; CRACK PROPAGATION; FRACTURING; HOLES (MECHANICS); RESIDUAL STRENGTH; COMPUTER PROGRAMS; CRACK TIPS; BUCKLING; ALUMINUM ALLOYS; DAMAGE; FAILURE; FASTENERS; LOADS (FORCES)




Fatique and Fracture Mechanics


Book Description




Riveted Lap Joints in Aircraft Fuselage


Book Description

Fatigue of the pressurized fuselages of transport aircraft is a significant problem all builders and users of aircraft have to cope with for reasons associated with assuring a sufficient lifetime and safety, and formulating adequate inspection procedures. These aspects are all addressed in various formal protocols for creating and maintaining airworthiness, including damage tolerance considerations. In most transport aircraft, fatigue occurs in lap joints, sometimes leading to circumstances that threaten safety in critical ways. The problem of fatigue of lap joints has been considerably enlarged by the goal of extending aircraft lifetimes. Fatigue of riveted lap joints between aluminium alloy sheets, typical of the pressurized aircraft fuselage, is the major topic of the present book. The richly illustrated and well-structured chapters treat subjects such as: structural design solutions and loading conditions for fuselage skin joints; relevance of laboratory test results for simple lap joint specimens to riveted joints in a real structure; effect of various production and design related variables on the riveted joint fatigue behaviour; analytical and experimental results on load transmission in mechanically fastened lap joints; theoretical and experimental analysis of secondary bending and its implications for riveted joint fatigue performance; nucleation and shape development of fatigue cracks in riveted longitudinal lap joints; overview of experimental investigations into the multi-site damage for full scale fuselage panels and riveted lap joint specimens; fatigue crack growth and fatigue life prediction methodology for riveted lap joints; residual strength predictions for riveted lap joints in a fuselage structure. The major issues of each chapter are recapitulated in the last section.




A Practical Engineering Approach to Predicting Fatigue Crack Growth in Riveted Lap Joints


Book Description

An extensive experimental database has been assembled from very detailed teardown examinations of fatigue cracks found in rivet holes of fuselage structural components. Based on this experimental database, a comprehensive analysis methodology was developed to predict the onset of widespread fatigue damage in lap joints of fuselage structure. Several computer codes were developed with specialized capabilities to conduct the various analyses that make up the comprehensive methodology. Over the past several years, the authors have interrogated various aspects of the analysis methods to determine the degree of computational rigor required to produce numerical predictions with acceptable engineering accuracy. This study led to the formulation of a practical engineering approach to predicting fatigue crack growth in riveted lap joints. This paper describes the practical engineering approach and compares predictions with the results from several experimental studies.













Fatigue '99


Book Description




Fibre Metal Laminates


Book Description

Fibre metal laminates were developed at Delft University of Technology in The Netherlands, from the beginning of the 1980s. This is a new family of hybrid materials consisting of thin metal layers bonded together by fibres embedded in an adhesive. As a result of this build-up, fibre metal laminates possess a mixture of the characteristics of both metals and composite materials. Initial development led to the `Arall' variant using aramid fibres, which was first applied on the C-17 military transport aircraft around 1990. Large-scale application became possible with a variant using glass fibres, dubbed `Glare', which was selected for the Airbus A380 super jumbo in 2001. This is the first book to discuss these new materials and it deals mostly with Glare. It covers most of the relevant aspects of the materials, from static mechanical properties, fatigue and impact to design, production and maintenance of aircraft structures. This book contains the basic information on these new materials necessary for engineers and aircraft operators alike.