Nuclear Resonance for the Nondestructive Evaluation of Structural Materials

It is appropriate that this presentation is in a session on new techniques because the program I will discuss this afternoon is sufficiently new that few concrete results are available to report. The program I will discuss was recently funded at Southwest Research Institute by AFOSR and involves examining the possibility of developing nuclear resonance techniques for the nondestructive evaluation of structural materials. What I hope to do this afternoon is to fill you in a bit with regard to the background involved in this program and bring you up to date regarding our research plans. I will discuss some of the experiments we hope to perform, and briefly describe a few results that were obtained in some related preliminary experiments

Measurement of Residual Stress Using Magnetic Barkhausen Noise Analysis

In this presentation we very briefly review the concepts involved in stress measurement by means of the Barkhausen effect, and cite the major instances of its practical application; the major part of the paper is devoted to a presentation of some recently obtained results regarding the effects of plastic deformation, and of biaxial stress fields

Nondestructive Evaluation of Advanced Fiber Reinforced Polymer Matrix Composites: A Technology Assessment

Because of their increasing utilization in structural applications, the nondestructive evaluation (NDE) of advanced fiber reinforced polymer composites continues to receive considerable research and development attention. Due to the heterogeneous nature of composites, the form of defects is often very different from a metal and fracture mechanisms are more complex. The purpose of this report is to provide an overview and technology assessment of the current state-of-the-art with respect to NDE of advanced fiber reinforced polymer composites

To the Detection of Bondline Flaws in Rubber/Metal Laminates a Comparison of the Sensitivity of Transverse and Lamb Waves

The use of adhesively-bonded structures is prevalent throughout the Navy since watertight rubber-to-metal bonds are required on many undersea systems including sonar transducers and electrical cables. In addition, adhesive bonds are used to transfer loads between rubber and metal adherends for limited structural applications. However, in each case the principal function of the adhesive bond is to provide watertight integrity for the bonded components in the hostile ocean environment where corrosion is of major concern

Investigation of Nuclear Acoustic Resonance for the Nondestructive Determination of Residual Stress

Nuclear acoustic resonance has been studied in cylindrical specimens of polycrystalline aluminum deformed in compression and tension. The acoustic absorption lineshape is found\u27 to be asymmetric and dependent on the amount of deformation. Analysis of the signals in terms of an admixture of the real and imaginary parts of the nuclear susceptibility has been performed. The linewidth measured from the experimental signals varies with deformation exhibiting a minimum between twelve and fifteen percent strain

Handbook of Nondestructive Evaluation (NDE) Capability and Reliability

Nondestructive inspection (NDI) is often the primary basis for establishing the initial flaw size that is used as the basis safe life analysis of components, structures and systems. It is often desirable to use a small initial flaw size for purposes of fatigue and fracture analysis, thus the capability of applied the nondestructive inspection procedure often becomes a primary design constraint. The introduction of fracture mechanics analysis in design applications has established requirements to quantify the capabilities of applied nondestructive inspection procedures for purposes of determining the “largest flaw that might be missed”. That flaw size, in turn, becomes the starting point for fracture mechanics analysis and for crack growth in fatigue life analyses. It is clearly desirable to start with a very small flaw size. In recent years, considerable effort has been expended in both meeting “attainable” flaw requirements and in improving NDI procedures capabilities to detect smaller flaws. Such efforts have identified uncertainties in fracture mechanics analysis procedures in predicting the behavior of small flaws and have greatly increased the complexity and sophistication of NDI procedures being applied

Measurement of Residual Stresses Around a Circular Patch Weld Using Barkhausen Noise

Welding is a common means of joining and repairing steel structures. In the case of steel tanks, circular patch welds are often used for repairing the structure after removal of a defective area. Unfortunately, the welding process also produces residual stresses which, if not relieved, can impair the integrity of the structure. Measurement of residual stresses produced by welding is needed, for example, to verify the effectiveness of a stress relief heat treatment which is typically used to remove weld-induced stresses