Amirkabir Journal of Mechanical Engineering

Amirkabir Journal of Mechanical Engineering

Dynamic Sensitivity Analysis of a Free–Free Aluminum Beam under Multi-Point Transient Impact Excitation Using Experimental Modal Analysis, Numerical Simulation, and Analytical Modeling with a Damage Identification Approach Based on an Enhanced Modal Assurance Criterion

Document Type : Research Article

Authors
mehrdad karimi 1
Masoud Javadi 2
1 Aerospace, Faculty of Postgraduate Studies, Shahid Sattari University, Tehran, Iran
2 Assistant Professor, Faculty of Aerospace, Shahid Sattari University, Tehran, Iran
10.22060/mej.2026.24330.7861
Abstract
This study presents a baseline-free framework for damage identification in free-free aluminum beams under multi-point transient impact excitation. The beam responses were measured using accelerometers, and modal parameters were extracted through an integrated experimental, analytical, and numerical approach. Experimental modal testing was conducted with six and nine excitation points, showing that a higher number of excitation locations improves the accuracy of identified mode shapes and natural frequencies.The analytical model was developed using Euler–Bernoulli beam theory, while a finite element model was built in Abaqus and verified against the analytical and experimental results. Several damage scenarios involving transverse cracks with different depths and locations were simulated to evaluate the sensitivity of the proposed method. The key contribution of this study is an improved Modal Assurance Criterion (CT-MAC) that combines mode shape curvature with contourlet transform to obtain noise-robust features, which are then classified by a one-dimensional convolutional neural network (1D-CNN). The proposed approach achieves 94% accuracy in detecting crack location and severity, with strong robustness against measurement noise.
Keywords
Multi-point Impact Excitation
Damage Detection
Contourlet Transform
Improved Modal Assurance Criterion (IMAC)
Convolutional Neural Network (CNN)
Structural Health Monitoring (SHM)
Subjects
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Amirkabir Journal of Mechanical Engineering
Volume 57, Issue 10
January 2026
Pages 1323-1358