Experimental assessment of axial strain distribution over the cross-section of electrical cables during bending vibrations

Abstract

High-Voltage cables (HV) that connect the battery to the electric drive of the electric vehicle are known to be important sources of vibrations. These vibrations are transmitted through the vehicle structure to the passenger compartment and result in radiated noise.

To minimize or eliminate unnecessary noise, it is required to understand the transmission process through this type of cables. Within this framework, the strain distribution over the cross-section of HV cables during bending is in this work investigated.

The evaluation of the strain distribution should be carried out by measuring the strain within the cable, which is composed of several smaller wires, wound into strands.

The most suitable sensing system for the current application results to be the Mach-Zehnder optical fibre interferometer, which is not only sensitive and responsive enough but also commercially attractive.

To ensure the feasibility of using a Mach-Zehnder optical fibre intereferometer, a mathematical model of an Euler-Bernoulli beam is composed and analyzed. Its flexural dynamic behavior is indeed similar to the one of the HV cables, provided that the beam is modeled with an equivalent material. By analyzing the mathematical model, the total elongation of the strand is found. The results suggest that the total strain can be measured by means of optical fibres.

The experimental setup of the Mach-Zehnder optical fibre transducer is then investigated. All the needed sensors and auxiliary components are described and their choice is motivated either by calculations or by comparison with other available alternatives.