R.D. Adams

The location of defects in structures from measurements of natural frequencies

Abstract A method of non-destructively assessing the integrity of structures using measurements of the structural natural frequencies is described. It is shown how measurements made at a single point in the structure can be used to detect, locate and quantify damage. The scheme presented uses finite-element analysis, since this method may be used on any structure. The principle may, however, be used in conjunction with other mathematical techniques. Only one full analysis is required for each type of structure. Results are presented from tests on an aluminium plate and a cross-ply carbon-fibre-reinforced plastic plate. Excellent agreement is shown between the predicted and actual damage sites and a useful indication of the magnitude of the defect is obtained.

A Vibration Technique for Non-Destructively Assessing the Integrity of Structures

A method of non-destructively evaluating the integrity of structures is described and applied to structures for which a one dimensional analysis is satisfactory. It is shown how vibration measureme...

Stress analysis of adhesive-bonded lap joints

Abstract Stresses in a standard metal-to-metal adhesive-bonded lap joint are analysed by a two-dimensional finite-element method and comparisons are made with previous analyses. Particular attention is paid to the stresses at the ends of the adhesive layer. Unlike previous work, which assumes the adhesive to have a square edge, the adhesive spew is treated as a triangular fillet. The highest stresses exist at the adherend corner within the spew. Linear elastic behaviour is assumed throughout. A rubber model is reported which confirms these results physically. Good agreement was also obtained between some practical results and the finite-element predictions.

The influence of local geometry on the strength of adhesive joints

Abstract This paper describes a two-part investigation into the effect of local geometry changes at the edges of the overlap in single lap joints. In the first part, finite element analysis has been used to model the effects on the stress distribution of geometry changes which are small in relation to the dimensions of the local geometry, in order to provide an improved model for failure prediction. The model used is that of an adhesive around a rigid corner, and the effect of rounding the corner has been considered. The second part deals with local geometry changes of the same order of magnitude as the dimensions of the geometry and their effect on joint strength. Three types of joint — one with a square-edged adhesive layer, one with a fillet of adhesive and one with an adhesive fillet plus a radiused adherend — were manufactured, tested and analysed. Improvements to the finite element models were also made following the results of part 1. It is found that finite element analysis is capable of predicting the significant strength increases that may be achieved in single lap joints by filleting the adhesive at the edges of the overlap and rounding the ends of the adherends.

Effect of Fibre Orientation and Laminate Geometry on the Dynamic Properties of CFRP

Theoretical predictions have been made of the effect of fibre orienta tion and laminate geometry on the flexural and torsional damping and modulus of fibre reinforced composites. Materials with fibres at + θ (off- axis), ±θ (angle-ply), 0/90° (cross-ply) and a general plate were in vestigated. In almost all cases, very good agreement was obtained between the theoretical prediction and the experimental results. Some limitations of plate theory for the torsion of angle-ply laminates were revealed and discussed.

Handbook of adhesion technology

Preface Introduction to adhesive bonding technology Part A - Theory of Adhesion Forces involved in adhesion Wetting Work of adhesion Spreading Theories of adhesion Part B - Surface treatments Surfaces General principles Surface treatments Surface assessment Primers and adhesion promoters Surface treatments of selected materials Part C - Adhesive and sealant materials Classification Composition Adhesive families Sealant families Selection Part D - Testing of adhesive properties Physical properties Thermal properties Failure strength tests Fracture tests Impact tests Special tests Part E - Joint design Constitutive adhesive and sealant models Analytical approach Numerical approach Special numerical techniques Design rules and methods to improve joint strength Design with sealants Design for impact loads Vibration damping Part F - Durability High and low temperature effects Humidity, water and chemicals Radiation and vacuum Fatigue load conditions Creep load conditions Combined temperature-moisture-mechanical stress effects Part G - Manufacture Storage Preparation Application Bonding equipment Environment and safety Part H - Quality control Quality control of raw materials Processing quality control Non-destructive testing Techniques for post-fracture analysis Part I - Applications Aeronautical industry Aerospace industry Automotive industry Rail industry Boats and marine Civil construction Electrical Shoe industry Part J - Emerging areas Molecular dynamics simulation and molecular orbital method Bioadhesion Bioadhesives Adhesives with nanoparticles Adhesion in medicine Adhesion in energy applications Recycling and environmental aspects Epilogue

Prediction and Measurement of the Vibrational Damping Parameters of Carbon and Glass Fibre-Reinforced Plastics Plates:

The objective of this investigation is to predict the natural frequency and specific damping capacity of laminated composite plates in various modes of vibration by using the finite element method.

Stress Analysis of Adhesive Bonded Tubular Lap Joints

Abstract The stresses in adhesive bonded tubular lap joints, subjected to axial and torsional loads, have been analysed using axisymmetric quadratic isoparametric finite elements. In the axial load case, the results are compared with a previously published closed-form solution and in the torsional case the results are compared with a closed-form solution presented here. The influences on the stress distributions of an adhesive fillet and of partial tapering of the adherends are also investigated, and an extension to the range of validity pf Goland and Reissners second criterion is proposed.

The Damping and Dynamic Moduli of Symmetric Laminated Composite Beams—Theoretical and Experimental Results

A method for predicting the dynamic properties of laminated composite beams has been developed in this work.

Stress Analysis and Failure Properties of Carbon-Fibre-Reinforced-Plastic/Steel Double-Lap Joints

The present paper considers the strength of CFRP/steel double-lap joints loaded in tension. A detailed stress analysis has been conducted of the shear and transverse tensile stresses in the joint, using an elastic-plastic model for the rubber-modified epoxy adhesive. The results of this analysis have been combined with the measured properties of the materials forming the joint in order to predict quantitatively the failure strengths of the various joint designs studied. There was good agreement between the theoretically predicted and experimentally measured strengths. These studies have led to a highly efficient design being developed.