Funding:

• • Department of Transportation/Federal Railroad Administration 

  • Burlington Northern Santa Fe (BNSF) Railway (in-kind)

Collaborators:

• • Transportation Technology Center, Inc., BNSF, Amtrak, Union Pacific, Norfolk Southern

Purpose:

To develop a wayside system to measure, in-situ, the Neutral Temperature (zero-thermal-stress temperature) of rails without the need for unfastening the rail and without a reference measurement.  This is a problem of in-situ thermal stress (or thermal load) measurement.

Synopsis:

Most modern railways use Continuous Welded Rail (CWR). A major problem in these structures is the almost total absence of expansion joints that can create buckling in hot weather and breakage in cold weather.  In order to prevent these accidents, knowledge of the rail Neutral Temperature-NT (or the rail temperature when the rail is at zero thermal stress) is critical. Unfortunately, a method able to determine the rail NT in situ, nondestructively, accurately and without the need for a reference measurement, is not existent. Actually, obtaining such a capability is commonly considered the "Holy Grail" of railway maintenance today. 

UCSD has been working towards this ambitious goal for several years. One technique under investigation is a method based on nonlinear guided wave propagation (the "Rail-NT" system), that has proved extremely effective in the laboratory but more challenging in the field. Other techniques under investigation have been (1) the adaptation, to the thermal stress measurement problem at hand, of the hole-drilling technique that is commonly utilized for residual stress measurements in metals, and (2) the application of the Electo-Mechanical Impedance (EMI) method for thermal stress measurements. Several of these studies at UCSD were enabled by the  UCSD’s Large-Scale Rail Buckling Facility, a one-of-a-kind 70-ft long track with the ability to impose controlled thermal loads through a rail switch heater wire. These and other studies towards an effective rail NT measurement system are continuously conducted at UCSD.

Selected Publications:

Non-linear Guided Wave Propagation method (Rail-NT System)

Lanza di Scalea, F., Srivastava, A. and Nucera, C., “Nonlinear Guided Waves and Thermal Stresses,” Chapter 9 of Nonlinear Acoustic Techniques for Nondestructive Evaluation, T. Kundu, ed., The Acoustical Society of America, Springer Nature Publishing, in press, doi 10.1007/978-3-319-94476-0_9, 2019. 

Nucera, C. and Lanza di Scalea, F., “Modeling of Nonlinear Guided Waves and Applications To Structural Health Monitoring,” ASCE Journal of Computing in Civil Engineering, Special Issue on Computing, 29(4), pp. B40140011- B401400115, 2015. 

Nonlinear Ultrasonic Testing for the Non-Destructive Measurement of Longitudinal Thermal Stresses in Solids. Inventors: Lanza di Scalea, F. and Nucera, C., International PCT Application no. PCT/US14/14945, Publication no. US-2015-0377836-A1, December 31, 2015. 

Nucera, C. and Lanza di Scalea, F., “Nondestructive Measurement of Neutral Temperature in Continuous Welded Rails by Nonlinear Ultrasonic Guided Waves,” Journal of the Acoustical Society of America, 136(5), pp. 2561-2574, 2014. 

Nucera, C. and Lanza di Scalea, F., “Nonlinear Wave Propagation in Constrained Solids Subjected to Thermal Loads,” Journal of Sound and Vibration, 333(2), pp. 541-554, 2014. 

Nucera, C. and Lanza di Scalea, F., “Nonlinear Semi-Analytical Finite Element Algorithm for the Analysis of Internal Resonance Conditions In Complex Waveguides,” ASCE Journal of Engineering Mechanics, 140(3), pp. 502-522, 2014. 

Phillips, R., Lanza di Scalea, F., Nucera, C., Fateh, M., and Choros, J., “Field Testing of Prototype Systems for the Non-destructive Measurement of the Neutral Temperature of Railroad Tracks,” CD-ROM Proceedings of the 2014 ASME Joint Rail Conference, Colorado Springs, CO, pp. 1-10, April 2-4, 2014. 

Nucera, C., Phillips, R., Lanza di Scalea, F., Fateh, M. and Carr, G., “RAIL-NT System for the In-situ Measurement of Neutral Temperature in CWR: Results from Laboratory and Field Tests,” Transportation Research Record: Journal of the Transportation Research Board, no. 2374, Washington DC, pp. 154-161, 2013. 

Nucera, C. and Lanza di Scalea, F., “Higher Harmonic Generation Analysis in Complex Waveguides via a Nonlinear Semi-Analytical Finite Element Algorithm," Mathematical Problems in Engineering, Special Issue on New Strategies and Challenges in SHM for Aerospace and Civil Structures, Hindawi Publishing Corporation, vol. 2012, doi:10.1155/2012/365630, 16 pgs., 2012. 

Hole-drilling Method

Zhu, X. and Lanza di Scalea, F., “Thermal Stress Measurement in Continuous Welded Rails Using the Hole-Drilling Method,” Experimental Mechanics, 57(1), pp. 165-178, 2017. 

Electro-Mechanical Impedance (EMI) method:

Zhu, X. and Lanza di Scalea, F., “Sensitivity to Axial Stress of Electro-Mechanical Impedance Measurements,” Experimental Mechanics, 56(9), pp. 1599-1610, 2016. 

Phillips, R., Zhu, X., and Lanza di Scalea, F., “The Influence of Stress on Electro-mechanical Impedance Measurements in Rail Steel,” Materials Evaluation, 70(10), pp. 1213-1218, 2012.