The rail: a sensor for measurement of forces applied by the wheel

Vehicle lateral stability during cornering can be investigated as a function of the resulting wheel-rail contact forces: lateral (Y) and vertical (Q). European Standards and stability studies on running vehicles denote the importance of knowledge of these values to set their limits, based on the assessment of the derailment ratio (Y/Q). The value of contact forces can be measured both on the wheelset and on the rail. In the latter case, the rail becomes a device to measure contact forces (Y and Q). The measurement of strain on the rail allows the computation of the resulting lateral forces (Y). Strain values are acquired on the surfaces of the rail web by means of strain gauge pairs. This paper illustrates the assessment process, experimental and theoretical, required for a sufficiently accurate calculation of lateral forces (Y) by establishing vertical surface stresses starting from measurement of strains