Static Response of Rail Track supported by Linear and Non-Linear Stiffness

Abstract

Introduction: The railway system can be viewed as a collection of structural components, each with distinct mechanical properties. These components are defined by their strength, stiffness, natural and forced frequency response function, which is influenced by their mass and elastic characteristics. These parameters determine the static and dynamic response or behavior of the rail. To analyze the behavior of the track, it is essential to understand the mechanical properties of the primary rail track elements.

Objectives: This paper focuses on the Discretely Supported Rail Beam Model with Linear Spring Stiffness and Nonlinear Spring Stiffness, compared the results using ANSYS for Static Analysis.

Methods: The Rails are linear elements of infinite length, making them suitable to be modeled as beams. They possess flexural stiffness in both the vertical and lateral directions, as well as compressive stiffness in the longitudinal direction. Additionally, rails have shear stiffness, although this is often overlooked in modeling. The rail fastening system commonly used with prestressed concrete sleepers consists of a resilient spring fastener, which works in parallel with a much stiffer rail pad. The load/deflection behavior of the fastening system is non-linear; however, some linearization of this behavior can be justified. Rail pads are primarily subjected to compression, which is constant due to the fastening system and rail traffic. The inclusion of rail pads helps reduce the impact of this force by lowering the effective track mass acting on the sleepers and ballast. The track components, initially considered to be exhibiting the linear behaviors, and later for more accuracy, they were studied for their nonlinear behavior by many researchers. The Static Response is often determined for the Track Modulus, an important parameter with respect to design, and maintenance of the railway track structure. There are different mathematical models suggested for obtaining the Track Modulus. The traditional method is Beam on Continuous Elastic Foundation (BOEF) Model, most widely discussed and studied in different aspects. The Winkler’s Hypothesis, considers Elastic Foundation as a system of Identical, Independent, Closely Spaced, Discrete and Linear Elastic Springs. In actual, the track components do not behave linearly.

Results: The Rail Beam Model with Linear Spring Stiffness and Nonlinear Spring Stiffness are compared against the results using ANSYS for Static Analysis.

Conclusions: Experimental and simulated results validate the Non-Linear Stiffness varies non-linearly having a quadratic behavior. The Band of Track between the Zero Deflection and Maximum Displacement with the Rail having Non-Linear Stiffness is TWO times against the Rail with Linear Stiffness.