PSI - Issue 84

Andy Duarte-Taño et al. / Procedia Structural Integrity 84 (2026) 280–287

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3. Numerical results and discussion 3.1. Case study 1: Synthetic vibration dataset

A synthetic vibration dataset was used to evaluate reconstruction performance under controlled conditions. The system consisted of a nine-degree-of-freedom (9-DOF) system (Fig. 2), subject to white noise base excitation. Acceleration responses of 1000 s duration were generated at a sampling frequency of 400 Hz for each DOF using modal decomposition and Newmark–Beta integration. The signals were segmented into non-overlapping windows of length =256 and compressed using the proposed autoencoder at different compression ratios. For this dataset, the frequency-domain loss ℒ was instantiated using the real and imaginary parts of the Fourier transform ( ℱ) : ℒ= ⋅ ( , ̂) + ⋅ ( {ℱ( )}, {ℱ( ̂)}) + ⋅ ( {ℱ( )}, {ℱ( ̂)}), (4) where + + =1 . To investigate the trade-off between waveform accuracy and spectral preservation, several weighting configurations ( , , ) were considered: 1 (1.00,0.00,0.00) , 2 (0.75,0.125,0.125) , 3 (0.50,0.25,0.25) , 4 (0.33,0.335,0.335) , 5 (0.25,0.375,0.375) , 6 (0.10,0.45,0.45) . For each configuration, compression ratios in the range ∈ {2, 4, 6, 8, 10, 12, 16} were evaluated.

Fig. 2. Numerical 9-DOF dynamic system utilized to generate the synthetic vibration dataset.

Fig. 3 reports the relative reconstruction error and correlation coefficient as a function of the compression ratio (CR). For each CR, the results correspond to the best-performing weighting configuration, selected based on the lowest RRE. Marker colours indicate the configuration yielding optimal performance at each compression level. Negligible reconstruction error is achieved for low compression ratios ( = 2 and 4 ), while satisfactory performance is retained up to = 8 ( > 0.95 ). Beyond this level, reconstruction quality degrades rapidly, motivating the selection of = 8 as a representative operating point for subsequent modal analysis.

Fig. 3. Synthetic vibration case: Average relative reconstruction error RRE and correlation coefficient across validation windows ( =256 ) for different compression ratios.