Low-speed impact locating method for composite material cell structure

Abstract

The invention discloses a low-speed impact locating method for a composite material cell structure, and belongs to the field of composite material structure engineering structure health monitoring. According to the method, an unconstrained optimization algorithm based on a Newton method is applied to solving the low-speed impact recognition problem of the composite material cell structure, and the low-speed impact fast recognition of the structure is achieved. Based on a sensor array technology, impact induction is applied to the structure to generate Lamb wave signals, and impact response signals of the composite material cell structure are collected. A certain sensor is used as the criterion, the wavelet analysis means is adopted, and the time differences of Lamb waves reaching the other sensors are extracted. The unconstrained optimization algorithm based on the Newton method is adopted to solve and locate a system of nonlinear equations, and therefore the position of an impact source is obtained. The impact source of the composite material cell structure can be recognized fast and effectively, recognition precision is high, and good engineering application value is achieved.

Description

Technical field: [0001] The invention relates to a low-velocity impact positioning method for a composite material grid structure, which belongs to the field of health monitoring of composite material structure engineering structures. Background technique: [0002] The grid structure is composed of reinforcing ribs and skin, and the reinforcing ribs are distributed in a regular polygonal grid, and the structure exhibits anisotropy. As soon as the grid structure came out, it has attracted great attention in the aerospace field due to its advantages of topology optimization, good corrosion resistance, good damage and diffusion resistance, and good designability. In order to meet the requirements of lightweight aerospace vehicles, the composite grid structure (AGS) has emerged. Composite materials have high specific strength, specific modulus and corrosion resistance, so more and more scholars apply composite materials to grid structures, and gradually promote their applicatio...

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Problems solved by technology

N.Takeda et al. (Takeya H, Ozaki T, Takeda N.Structural health monitoring of advanced grid structure using multipoint FBG sensors[C] / / Smart Structures and Materials s2005.Proc of SPIE:Vol.5762.2005:204 from the University of Tokyo, Japan -211.) (Amano M, Takahashi I, Okabe Y, et al. Identification of damage location in advanced grid structures using fiber bragg grating sensor[C] / / Smart Structures and Materials2005.Proc of SPIE:Vol.5765,2005: 644-655.) First, the research on the health detection of the grid structure of the aircraft rudder was carried out, and the cracking of the ribs and the delamination of the ribs and the skin were successfully detected by comparing the strain difference before and after the damage; More serious analysis is effective; Chen Zhenying et al. from Nanjing University of Aeronautics and Astronautics ("Research on Damage Location of Advanced Composite Grid Reinforced Structure (AGS)", Master's Thesis, Nanjing University of Aeronautics and Astronautics, 2011) applied the mode shape Curvature method successfully detects rib debonding and fracture damage of composite grid structure, but this method cannot detect skin damage of grid structure; Lan Youze et al. ("Composite material grid based on frequency response function Research on Damage Detection of Grid Structure", master thesis, Nanjing University of Aeronautics and Astronautics, 2013) Aiming at the shortcomings of traditional modal strain energy that cannot detect AGS skin damage, a damage detection method based on the imaginary part of the structural frequency response function is proposed, but This method is very susceptible to environmental noise, so it is difficult to be widely used in engineering

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