Principal Investigator: Joseph Turner
About this Project
Brief Project Description & Background
The project is focused on the use of ultrasound for concrete tie inspection with frequencies higher than previously used. In this case, the waves will scatter from the internal structure, including any damage present. Statistical signal analysis methods will be used to relate the measured data to the damage state.
The proposed research exploits high frequency ultrasonic methods (> 50 kHz) to enhance the detection of small-scale damage in concrete railroad ties. Statistical wave propagation methods will allow time-frequency characteristics to be identified and correlated with different types of internal damage.
The development of new inspection tools for damage detection in concrete railroad ties will enhance railroad safety by allowing the current structural integrity of ties to be determined. Such quantitative methods may allow the remaining life to be predicted in order to avoid catastrophic failures. In addition, effective tools for structural health monitoring will allow the state of repair with respect to concrete ties to be greatly improved.
Damage to concrete railroad ties may be caused by many factors, including manufacturing defects, overloading, mechanical fatigue, thermal damage, chemical damage, or a combination of these factors. Damaged ties are a substantial safety risk, and the replacement of ties is a significant expenditure annually. Current visual inspections of ties can quantify some damage preventatively, but often internal damage is substantial by the time the cracks reach the tie surface such that they may be detected. Thus, new methods for the quantitative assessment of damage using nondestructive methods are essential for determining the structural integrity of ties and for predicting their remaining usable life. The proposed research will address these needs through the study of ultrasound propagation in concrete ties at frequencies higher than those previously explored for tie inspection (e.g., impact echo). The research project is based on a firm theoretical foundation, and exploits previous research from the PI associated with the propagation, scattering, and dissipation of ultrasound in concrete. The influence of various types of damage, as identified by Union Pacific, will be explored with respect to the characteristics of ultrasound. The proposed high frequency (> 100 kHz) approach will improve the detection of small-scale damage by using wavelengths that are shorter than those explored previously. The heterogeneous nature of concrete necessitates a statistical approach in order to extract quantitative information from the measurements. It is anticipated that the research will lead to new techniques for assessing damage in concrete ties. The proposed research also will have a significant impact on the educational training of one graduate student in nondestructive evaluation techniques applied to essential infrastructure materials.