Feasibility of digital image correlation for railroad tie inspection and ballast support assessment. (June 2017)

• Record Type: Journal Article
• Authors: Sabato, Alessandro; Niezrecki, Christopher
• Is Part Of: Measurement. Volume 103(2017)
• Page Start: 93
• Page End: 105
• Publication Date: 2017-06
• Subjects: Ballast -- Crosstie -- Digital image correlation -- Railroad -- Structural health monitoring; Weights and measures -- Periodicals; Measurement -- Periodicals; Measurement; Weights and measures; Periodicals; 530.8
• DOI: 10.1016/j.measurement.2017.02.024
• Languages: English
• ISSNs: 0263-2241

Abstract

Highlights: A novel system using 3D-DIC is proposed to assess the crossties-ballast conditions. The system allows detecting crosstie's deflection profiles increasing track safety. Measurement of full-field displacement field over the crosstie's entire length. Optical system's resolution is on the order of 10 −5 m. Optical system's accuracy is comparable to that of a high-accuracy LVDT. Abstract: Structural Health Monitoring (SHM) of aging railway tracks is important for safety, to prevent catastrophic failure, and to reduce maintenance costs. The tracks and foundations are complex systems that may contain defects or damage including internal rail cracks, pitting or surface erosion, degradation of ballast support, or railway crosstie-ballast failures. In recent years, interest has grown in performing SHM by measuring structural deformation, full-field strain, and geometry profiles using three-dimensional (3D) Digital Image Correlation (DIC) systems. In this study, a novel approach to use DIC and pattern projection to assess the deformation of railway tracks is proposed. The proposed sensing approach should allow a railcar mounted sensing system to perform interrogation while moving at typical operating speeds (e.g. 60 mph). The feasibility of the proposed 3D DIC system is evaluated through extensive laboratory testing. The approach's ability to measure the crosstie's full-field displacement and shape (i.e. at levels similar to what is found in the field) as different loading conditions are applied is demonstrated. The influence of motion similar to what might be found in a railroad service environment on the accuracy of the measurements is also quantified.