Impact Force Reconstruction in Composite Structures Using Wavelet Transform and Low-Frequency Response Components

Aircraft composite structures are vulnerable to barely visible impact damage (BVID) caused by external impacts. Timely identification of impact forces through sparse sensor networks is critical for structural maintenance and flight safety. This article proposes an impact force reconstruction method based on wavelet transform (WT) and low-frequency response components (LRCs). The impact forces at unknown locations can be identified using the limited training data. The method extracts LRCs via WT, ensuring stable system modeling by avoiding high-frequency disturbances. A similarity-based decision strategy adaptively selects sensor combinations and LRCs for interpolation, enabling effective impact force reconstruction through sparse networks. The approach is applicable to both reinforced and flat structural areas, offering a balanced solution between monitoring cost and reconstruction capability. Validation is provided through low-velocity impact experiments on composite stiffened panels.

I. Introduction

Composite materials are gaining more and more attention and applications in the aerospace field due to their excellent comprehensive performance. Due to the inherent mechanical properties of composites, composite structures are susceptible to the formation of barely visible impact damage (BVID) caused by low-velocity impact loads [1], [2], [3]. During the service process, BVID will extend to progressively reduce the load carrying capacity of the structure [4], [5]. Impact monitoring of composite structures is an enduring subject of structural health monitoring (SHM) in engineering applications.