Feasibility Study for Detection and Quantification of Corrosion in Bridge Barrier Rails

Three non-destructive technologies were evaluated for their abilities to detect and quantify corrosion damage in reinforcing steel used in bridge barrier rails

Development of Magnetic Inspection Techniques for Evaluation of Fatigue Damage and Stress in Low Alloy Steels

It is known that the magnetic properties of ferromagnetic materials change under fatigue and applied loads (1,2,3). These changes in the magnetic properties could be used as indicators of the stress state of the material, or possibly for predicting the remaining fatigue life. Previous reports have shown successful implementation of this magnetic measurement technique for NDE of steel samples in a laboratory enviroment. However, for this technique to be practical, a field-usable instrument must be developed. This paper will describe measurements using one such instrument, the Magnescope. It will also discuss the techniques used to evaluate the effects of applied loads, both tensile and compressive, and low cycle fatigue on a variety of materials

Engineering studies for fluorescent penetrant inspection with a focus on developer application methods

Fluorescent penetrant inspection (FPI) is the most widely used global inspection method, playing a particularly important role in aviation. Given the contribution that reliable implementation of the FPI process can make to flight safety, the US Federal Aviation Administration (FAA) has funded a programme to assess the FPI parameters and their role in effective detection of typical flaws. Iowa State University’s Center for NDE (CNDE) has led a team that includes many industry partners from the aviation industry during this six-year programme. The industry partners have provided guidance and prioritisation input, and in many cases access to internal data, samples or use of facilities to support the programme. The focus of the programme has been on quantitative assessment of FPI performance using a combination of data gathering methods, which has included indication luminance as measured using a photometer, UV-A indication appearance using a fluorescence stereomicroscope, and in some cases the more traditional probability of detection (POD) study. Numerous studies have been completed, although results of developer studies will be the focus of this paper. Choice of indication development parameters starts with the selection of the developer form. All four forms have been evaluated during this programme: dry powder, water-soluble, water-suspendible, and nonaqueous wet developers. The results of the developer studies are presented below along with key ‘lessons learned’

Recent Advances in Model-Assisted Probability of Detection

The increased role played by probability of detection (POD) in structural integrity programs, combined with the significant time and cost associated with the purely empirical determination of POD, provides motivation for alternate means to estimate this important metric of NDE techniques. One approach to make the process of POD estimation more efficient is to complement limited empirical experiments with information from physics-based models of the inspection process or controlled laboratory experiments. The Model-Assisted Probability of Detection (MAPOD) Working Group was formed by the Air Force Research Laboratory, the FAA Technical Center, and NASA to explore these possibilities. Since the 2004 inception of the MAPOD Working Group, 11 meetings have been held in conjunction with major NDE conferences. This paper will review the accomplishments of this group, which includes over 90 members from around the world. Included will be a discussion of strategies developed to combine physics-based and empirical understanding, draft protocols that have been developed to guide application of the strategies, and demonstrations that have been or are being carried out in a number of countries. The talk will conclude with a discussion of future directions, which will include documentation of benefits via case studies, development of formal protocols for engineering practice, as well as a number of specific technical issues

Status of FAA Studies in Thermal Acoustics

As with many aerospace applications, commercial jet engine components are operated in demanding environments, often at extreme temperature and stress conditions. The predominant used surface inspection method used on these components is fluorescent penetrant inspection. Research has been ongoing for a number of years on a new technology using a short burst of low frequency ( ∼ 20 KHz) ultrasound to “heat up” cracks and make them visible in the infrared range. The basic premise of the Thermal Acoustic method is to use an energy source with recent efforts using an ultrasonic horn originally intended for use in ultrasonic welding to excite the component. The energy source causes an increase in local heating, which is detectable with infrared cameras typically used in Thermographic inspection. While considerable research is underway, additional information on the sensitivity and applicability of this technique to engine components and alloys is needed prior to widespread use in the aviation industry. The purpose of this program is to provide additional data to determine applicability of this method to engine components

NONDESTRUCTIVE DETECTION OF AN UNDESERABLE METALLIC PHASE, T1, DURING PROCESSING OF ALUMNUM-L THUMALLOYS

A method is disclosed for detecting the T1 phase in aluminum-lithium alloys through simultaneous measurement of conductivity and hardness. In employing eddy current to measure conductivity, when the eddy current decreases with aging of the alloy, while the hardness of the material continues to increase, the presence of the T1 phase may be detected