Dynamic response distortion due to changing excitation frequency

Abstract

This study addresses the distortion in system response caused by continuously changing excitation frequency. The distortion leads to reduced resonance peak amplitude and shifts the resonance frequency as well. The novelty of this work lies in providing an analytically established, model-based methodology that not only describes but also predicts and enables one to control this distortion, in contrast to existing studies that mainly describe the phenomenon characteristically [1], [2]. The proposed approach incorporates the influencing parameters, such as the sweep direction and rate of linearly changing excitation frequency, and applies a first-order ODE (ordinary differential equation) formulation to approximate the distortion. This enables a sensitivity analysis across frequency and damping ranges, which has not been previously reported in the literature. The methodology is validated with experimental data from an E-drive system, demonstrating how optimal sweep rates and other test conditions can be derived from model fitting. While nonlinear effects may occur in E-drives, the present study focuses on their linear regime to isolate distortion effects. The findings provide both fundamental insights into resonance distortion and practical guidelines for improving the accuracy and reliability of swept-excitation-based NVH (noise, vibration, harshness) measurements in engineering applications.