Investigation of track stiffness quality based on rail foot bending strain utilizing structure optimization methods

Track stiffness variation is one of the major sources of track quality deviation. To investigate track stiffness, it is common to install trackside sensors to measure track answer under extern excitation. In this research, rail foot bending strain at the middle of rail seats along the track under normal train runs is recorded by strain gauge to investigate track stiffness quality. To determine track stiffness quality based on the measurement strain result, there exists two difficulties: firstly, the dynamic wheel load is time-variant and unknown; secondly, the relationship between rail seat stiffness and rail bending strain is a multi-input-multi-output function, which makes a direct analytical solution difficult.
The first issue is solved by introducing the concept of the strain-location curve. The second issue is solved by transferring the problem to a structural optimization problem. The commercial structure optimization software Ansys Designxplorer® is used to processing field measurement result and a good match is achieved.