Experimental and numerical assessment of oblique loading quasi-static testing of railway anticlimbers

Abstract

An oblique loading angle test was devised in order to subject the anticlimbers of railway vehicles to a predetermined perpendicular load as well as a predetermined bending moment. The motivation for this type of test was the Standard and industry requirements for anticlimbing devices to prevent overriding and resist a determined perpendicular force while dissipating energy. Anticlimbing units, based on shrinking circular deformation tubes, were subjected to compression tests. The oblique loading was applied by placing the anticlimbing unit on a plate at an angle to the centreline of the unit. A numerical model was validated against the test results, in order to infer the bending moment subjected to the anticlimber unit. The bending moment on the anticlimbers was expected to be fully determined by the perpendicular force and the length of the tube. The predicted bending moment measured by the validated numerical model was smaller than anticipated and was potentially unpredictable. The discrepancy was caused by the irregular distribution of the normal force at the interface of the test machine and the anticlimber head. As a result, the devised angle test was proved unsuitable to induce a consistent and predictable bending moment on the anticlimber units of railway vehicles.

On the effect of anisotropy on the performance and simulation of shrinking tubes used as energy absorbers for railway vehicles

“…It can be noted that the friction coefficient ranges from µ = 0.02 to 0.25, with modal values of µ = 0.05 during expansion, with this increasing to 0.11 for shrinking tubes. The authors of the present study have previously observed [39] a friction coefficient value of µ = 0.05 for shrinking tubes used as rail vehicles anti-climbers. Indeed, such adjustments may obscure the effect of the other parameters, such as the properties of the material used to manufacture the tubes, on the performance of the energy absorbers.…”

“…Tensile test samples are typically extracted from the longitudinal direction of the tube, as the wall thickness of most tubes makes it impracticable to extract tensile samples in the transverse direction. This approach was followed by several researchers quoted in the introduction [22] [31] [35] [37] [39]. Herein, data obtained from samples extracted from both the longitudinal and transverse directions of the tube is implemented.…”

Experimental research of absorption properties of rigid foam filled circular seamless tube energy absorber under quasi-static axial load

“…PU foam specimens with a density of 170 kg/m 3 and dimensions 30x30x30 mm were used for experimental determination of the foam properties (Figure 4(a)) by uniaxial compression tests in accordance with ISO 844 standard. 24 The axial force was applied on the PU foam samples, using Universal Testing H10K-s machine with maximum of 5 kN load cell (Tinius Olsen, USA). Figure 4(b) shows engineering compressive stress–strain curve (average values) of the representative samples, obtained by testing.…”

“…to be mounted immediately behind it in the vehicles bearing structure, Fig 1a. Also, this absorber can be a part of the shrinking anticlimber system on the electric/diesel train described by Moreno et al [26], Fig. 1b.…”

“…to be mounted immediately behind it in the vehicles bearing structure, Figure 1 (a). Also, this absorber can be a part of the shrinking anticlimber system on the electric/diesel train described by Moreno et al, 21 The experimental results presented in this paper were obtained by testing scaled samples, and done with the aim to show impact of rigid PU foam on absorption properties of shrinking tube absorber. Numerical analyses have been realised using ANSYS Workbench.…”