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Introduction: Current research has mostly simplified CFRP components as isotropic media or homogenized them as anisotropic media, which fails to present the actual acoustic propagation behavior inside the CFRP components and restricts the accuracy of decoupling sound line tracking results and defect feature information.Method: Based on clarifying the influence of fiber direction on the spatial distribution of CFRP elastic properties, this paper proposes an acoustic modeling method for CFRP multi-directional plates considering the coupling effect of multi-layer structure and elastic anisotropy.Results: There are two main innovations: 1. The model is optimized using the Voigt representation method, which can quantitatively characterize the elastic anisotropy of any homogeneous material with a 6 × 6 elastic stiffness matrix containing 21 independent elastic constants. In this paper, the elastic stiffness matrix only includes five independent elastic constants; 2. Finite element simulation is used to analyze the propagation rules of ultrasonic waves inside CFRP and compare the detection methods with or without sound coupling layer.Discussion: The acoustic characteristics of the sound coupling layer are changed to find the optimal coupling method, reduce the refraction of ultrasonic waves in the specimen layer, and make the sound line path more accurate.

This research article proposes experimental methods for monitoring damage propagation of Carbon Fibre Reinforced Plastic (CFRP) components under vibration fatigue. High cycle fatigue (HCF) behaviour of composites is often not as dramatic as that of metal alloys, where any crack initiation might rapidly lead to failure. Instead, composites HCF behaviour is often a prolonged state of continuous degradation of the resin-to-fibre bonding. Furthermore, the interlaminar contact conditions at any opening delamination cause complex dynamic responses, which can be nonlinear and temperature dependent. Vibration fatigue is generally caused by large deformations which can be suitably measured by non-contact measurement systems. Hence, this paper explores the application of the scanning laser vibrometer to monitor damage propagation of CFRP components under vibration fatigue loading. The objective is to show how this measurement system can systematically implement a set of experimental methods aimed at monitoring the dynamic properties during the crack propagation caused by fatigue. The set of experimental techniques are autonomously executed by a custom-made control panel. A thermal camera is also part of the measurement chain and provides qualitative information about location of temperature hot spots and damage evolution. [ABSTRACT FROM AUTHOR]

Nowadays, carbon fibre reinforced polymers (CFRP) are widely utilized for the construction of light weight aircrafts. The main technologies for assembly and joining composite aircraft structures are drilling and bonding. Failures of bonded joints or bolted attachments can occur within the composite structure; therefore, each manufactured composite structure needs to be accurately inspected. In this paper, an advanced ultrasonic non-destructive evaluation technique based on full volume ultrasonic scanning is applied for the characterization and the 3D thickness reconstruction of two diverse CFRP aeronautical components to obtain a quality assessment of the process and a 3D representation of the defects. [ABSTRACT FROM AUTHOR]